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FEBRUARY 2017 • ISSUE 186 ABN 71 000 876 040 ISSN 1443-2471Australian Society ofExploration GeophysicistsPREVIEWNEWS AND COMMENTARY FEATUREOil price and drilling activity recover in 2016 The development of optically pumpedEarthquake magnitudes magnetometer systems and their applicationsIdentifying and characterising aquifers in in Australia: Part 2saline environmentsNew insights into the Mount Isa EasternSuccession using multifactorial analysisMore seismic attributesMy digital twin













Executive brief ASEG newsExecutive briefThe Federal Executive of the ASEG To everyone who has renewed for The planning for the AGM in Brisbane(FedEx) is the governing body of the 2017 – congratulations and a very big has started, if you would like to attendASEG. It meets once a month, via thank you! the AGM in Brisbane let me know and Iteleconference, to see to the will keep you in the loop regarding timeadministration of the Society. This brief A particular welcome to the new student and location. If you are interested inreports on the last monthly meeting, Members, student membership is up volunteering for the Federal Executivewhich was held in December. We hope 51%!!! Remember early and mid-career please let us know. A very big thank youyou have found these reports interesting Members can join the ASEG Young to the 2016 Federal Executive committeeand informative. If there is more you Professionals Network https://www. and a very big thank you to the localwould like to read about on a regular aseg.org.au/about-aseg/aseg-young- state Branch Committees for all of yourbasis just get in touch with me (Marina) professionals. hard work during 2016.and I will expand the 2017 briefsaccordingly. Anyone who would like to I hope you have had a chance to look at Cheers to 2017!see the full minutes of the monthly our new website, its looking really great.meetings should add their name to the Join us on Facebook and please let me Marina Costelloemailing list maintained by the Secretariat. know if you found it easy to renew this Honorary SecretaryFedEx also holds planning meetings twice year. [email protected] year.Society financesThe Society’s financial position at theend of November:Year to date income $529 541.95Year to date expenditure $720 780.59Net assets $1 104 494.70MembershipAt the end of 2016, the Society had 1151Members. Overall membership is downslightly on 2015, Active/Associatemembership is down 11%, and retiredmembership is up. The ACT and SA/NTmembership is up, but unfortunatelynumbers in WA and Vic have decreased. This Jalander fluxgate magnetometer is from the ASEG virtual museum collection and was generously donated by John Stanley, formerly lecturer at the University of New England and inventor. Fluxgate magnetometers were a new breed of ‘electronic’ magnetometers, more sensitive than variometers, first invented in Germany in 1928 but not used extensively until just before, and during, WWII.This instrument was built in the 1950s to 60s by the Jalander Company in Helsinki, Finland, and weighed a light 1.3 kg. Like all fluxgates, it only measures the vertical component of the field. The fluxgate module is mounted internally concentric with the instrument housing. To operate, after turning the instrument on, it must be suspended to hang vertically and steadied to align the levelling bubble in the centre of its bull’s eye.When steady, the relative value of the vertical component of the magnetic field can be read off the analogue scale. A switch can be used to select the most appropriate range scale.The typical measurement time is only 15 seconds and best resolution for this non-stabilised unit is 10 nT.6 PREVIEW FEBRUARY 2017

CommitteesASEG newsNews from the ASEG Research FoundationAt the 2016 ASEG Conference in complete their post graduate degrees, be it has sufficient funds in the bank toAdelaide two events were held that were it at Honours, Masters or PhD level. Each cover its forward commitments.of particular significance to the ASEG year students’ supervisors submit workResearch Foundation; the conference proposals on behalf of their students. Two I thank everyone who attended the ASEGdinner and the lunch held to acknowledge committees of the Research Foundation, conference in Adelaide for theirProfessor David Boyd’s ASEG Gold one for minerals and the other for generosity in supporting the ASEGMedal. petroleum, assess the merit of the various Research Foundation. I encourage you all proposals and make recommendations to think of the ASEG ResearchThe conference dinner was held at the about which projects to support. Foundation among the charitableAdelaide Cricket Ground with a donations that you make every year. It iscricketing theme. It proved to be a very Funding the Research Foundation is an a worthwhile cause that is investing inenjoyable night. A number of fund ongoing challenge and relies on the the future of geophysics and the futureraising activities were carried out donations of companies, individual professionals of our industry. It is easy toincluding an auction of several bottles of Members and importantly the ASEG donate through the ASEG website and allAustralia’s finest wines and a blind itself. Funds available fluctuate from year donations are fully tax deductable.auction for a variety of cricket to year with the level of donations andmemorabilia gathered together by the also with the overall financial health of Phil HarmanAdelaide Conference Organising the ASEG. The Foundation is only ever ASEG Research Foundation ChairCommittee. In total nearly $3000 was able to commit to support projects when [email protected] on the night, and severalcommitments were made for further Hydrogeologic Propertiesdonations after the conference. Measured with NMRThe success of the evening was made Water Contentpossible by the assistance of fellow PorosityFoundation Members and also with thehelp of the Conference Organising PermeabilityCommittee, in particular Kelly Keates of TransmissivityZonge in Adelaide who was a great Specific Yieldsupport in making it all happen. 㪣㫆㪾㪾㫀㫅㪾㩷㫋㪿㫉㫆㫌㪾㪿㩷㪧㪭㪚㩷㫆㫉㩷㫆㫇㪼㫅㩷㪿㫆㫃㪼㫊㩷Also at the conference a lunch was held 㩽㩷㪥㫆㫅㪄㫀㫅㫍㪸㫊㫀㫍㪼㩷㫊㫌㫉㪽㪸㪺㪼㩷㫀㫄㪸㪾㫀㫅㪾㩷to celebrate the award of the ASEG GoldMedal to Professor David Boyd. Sales | Rentals | ServicesDonations from those attending the lunch www.vista-clara.comwere directed to the ASEG ResearchFoundation and totalled in excess of$2500. Sadly David passed away just acouple of months after the conference.Nevertheless his life’s work, as apractical geophysicist and as a truly greatteacher, were well honoured at the lunch.It seems fitting that money raised at thelunch should be directed towards assistingfuture students. Thanks to Dave Isles fortaking the lead on this event and forthinking of the Research Foundation as abeneficiary.The Research Foundation has passed its25th year and has over the yearssupported numerous projects with thetotal moneys granted now exceeding$1.2m. It was set up with the fairlymodest aim of providing financial supportto enable geophysical students inAustralian institutions to carry out thefield and laboratory work necessary to FEBRUARY 2017 PREVIEW 7

Committees ASEG newsNews from the ASEG History CommitteeThe ASEG History Committee is one of suitable and convenient location are yet Preview 173 for the period coveringthe largest ASEG Committees and is very to be found. Preview 53 – 166, appears in Table 1.active. 2016 was another busy year. Someof the highlights and a summary of the The History Committee aims to add other Activities planned for the future includeCommittee’s plans for the future are items of interest to the History section of firstly, continuing to add to the virtualpresented here. the website as they come to hand. Two museum and other parts of the History new papers were added in 2016: ‘A Brief section of the website, and continuing toAn exciting recent development has been History of Exploration Geophysics contribute articles to Preview. Also, athe initiation of the ‘virtual’ or ‘online’ Education in Australia’ and ‘A Survey of series of biographies is planned of keymuseum. The first inputs to this museum Educators in Australian Universities’. The Members of ASEG, such as Lindsaycan now be viewed in the History Section Committee also aims to have items of Ingall, the second President; Laricof the website, including 15 contributions historical interest in as many issues of Hawkins, the first 1st Vice-President, etc.from John Stanley. More contributions Preview as possible. In 2016 there were If you have other names to add to this listare in the pipe-line but if you think you history feature papers in Previews 180, or, more importantly, are able to assistcould add to the museum please contact 181, 184, and 185. The second part of with writing a biography, please contactthe Chair of the History Committee. High John Stanley’s paper on the development the Chair.definition photos are required, where of cesium magnetometers in Australiapossible, plus a brief description of the appears in this issue of Preview and three Also contact the Chair if you would likeitem – like the descriptions of the items other papers are in preparation for future to serve on the History Committee or toalready on display. This digital museum issues. be on the mailing list for regular reports.has evolved from the aim to collect anddocument old equipment but so much has A full list of all items of published since Roger Hendersonbeen received, or is forthcoming, that the Preview 166 (October 2013), which History Committee Chairphysical space required for storage and a continues from an earlier list published in [email protected] 1. Items of historical interest published in Preview since October 2013Issue no. Starting page Title Type169 12 Kenneth Zonge 1936–2013 (by Larry Hughes et al.) Obituary171 17 Hugh Rutter 1941–2014 (by Kim Frankcombe, Bob Smith, Jim Lalor & Phil Schmidt) Obituary171 18 The geophysics of the Olympic Dam discovery (H. Rutter and D. J. Esdale) Feature172 22 Alan Appleton 1934–2014 (by Dave Cockshell) Obituary172 39 SIROTEM – Australia’s first locally invented TEM system (Roger Henderson) Feature173 16 History articles in Preview (Roger Henderson and Ann-Marie Anderson-Hayes) News173 18 Don Gray 1931–2014 (by Alla Metlenko) Obituary173 18 Trevor Jones 1949–2014 (by Marina Costelloe) Obituary173 44 The ASEG Research Foundation celebrates its 25th anniversary (Doug Roberts) Feature174 13 Robert Sheriff 1922–2014 (by Norm Uren) Obituary175 34 Peter Gunn remembers his life as a geophysicist (by Peter Gunn) Feature176 14 Alex Copeland 1950–2015 (by Kim Frankcombe et al.) Obituary176 17 Dave Hutchins 1948–2015 (by Bob Timmins) Obituary177 14 Christopher Wiles 1947–2014 (by Mike Sexon et al.) Obituary179 53 The first gravity meter in Australia in 1890s (Roger Henderson) Feature180 40 The first lecturer in exploration geophysics in Australia (Roger Henderson) Feature181 38 Lewis Albert Richardson: a pioneer of exploration geophysics in Australia (Bob Richardson) Feature184 36 High productivity vibroseis techniques: a review (Tim Dean) Feature185 46 The development of optically pumped magnetometer systems and their applications in Australia: Part 1 (John Stanley) Feature8 PREVIEW FEBRUARY 2017

Notice of Annual General MeetingASEG NewsNotice of Annual General Meeting (AGM)The 2017 AGM of the Australian Society (iii) a Secretary, andof Exploration Geophysicists (ASEG) (iv) a Treasurer.will be held at the XXXX Brewery,Black St and Paten St, Milton, Brisbane, These officers are elected annually by aon 10 April. The meeting will be hosted general ballot of Members. Andrea Rutleyby the Queensland Branch. Details to was elected as President-Elect in 2016be supplied via email. Drinks will be and as such will stand for the position ofavailable from 6:00 pm and the meeting President.will begin at 6:30 pm. The following offices are alsoThe business of the Annual General recognised:Meeting will be: (i) Vice President,• To confirm the minutes of the last (ii) the Immediate Past President (unless preceding general meeting; otherwise a member of the Federal• To receive from the Federal Executive Executive), reports on the activities of the Society (iii) the Chair of the Publications during the last preceding financial year; Committee, (iv) the Chair of the Membership• To receive and consider the financial Committee, accounts and audit reports that are (v) the Chair of the State Branch required to be submitted to Members Committees, and pursuant to the Constitution and to law; (vi) up to three others to be determined by the Federal Executive.• To consider and if agreed approve any changes to the ASEG Constitution; These officers are appointed by the Federal Executive from the volunteers• To report the ballot results for the wishing to serve the Society. election of the new office holders for the Federal Executive; Nominations for all positions (except Past President) are very welcome. Please• To confirm the appointment of auditors forward the name of the nominated for 2017. candidate and the position nominating for, along with the names of two MembersThe AGM will be followed by a scientific who are eligible to vote (as Proposers), topresentation. The speaker and title will be the Secretary:advised closer to the event. Marina CostelloeInvitation for candidates for the ASEG SecretaryFederal Executive Care of the ASEG Secretariat PO Box 576Members of the Federal Executive Crows Nestserve in an honorary capacity. They NSW 1585are all volunteers and Members are Tel: (02) 9431 8622encouraged to consider volunteering for Fax: (02) 9431 8677a position on the Executive or on one Email: [email protected] its committees. Current members arelisted in Preview; please contact one of Nominations must be received viathem if you wish to know more about post, fax or email no later than COBvolunteering for your society. Tuesday 7 March 2017. Positions for which there are multiple nominations willIn accordance with Article 8.2 of the then be determined by ballot of MembersASEG Constitution ‘…The elected and results declared at the Annualmembers of the Federal Executive are General Meeting.designated as Directors of the Society forthe purposes of the [Corporations] Act.’ Proxy forms and further details of the meeting will be sent to Members priorThe Federal Executive comprises up to to the meeting by email and made12 members, and includes the following available to Members on the Society’sfour elected members: website.(i) a President,(ii) a President Elect, FEBRUARY 2017 PREVIEW 9

Branch news ASEG newsASEG Branch newsNew South Wales sent information about the AGM as the Mike Hatch our Secretary for all of their date approaches. hard work, especially given the amountIn November, Ned Stolz and Bob of time that was also devoted by themMusgrave from the Geological Fiona Duncan and all the others on the committeeSurvey of NSW presented a talk [email protected] who helped on the ASEG-PESA-AIGentitled ‘What’s been happening at the Conference Organising Committee. EveryGeological Survey of NSW? Current South Australia & Northern Territory committee member’s efforts are muchand upcoming geophysics, geology and appreciated by me and the local Branchcrustal interpretations’. Ned, the new Since the last edition of Preview the alike. For everyone continuing I lookmanager of geophysics and modelling, SA/NT Branch has only held one event, forward to working with you in 2017. Weprovided an update on activities and the final for 2016, marking a very relaxed also welcome any interested Members toproducts from the Geological Survey and enjoyable end to the year on the way the local committee and any commitment,including airborne magnetic acquisition to the Christmas and New Year period. large or small, is appreciated.and field mapping programmes. This was Our November technical evening, thefollowed by Bob Musgrave presenting Annual Student Night and Christmas Please keep an eye out for events in 2017results from potential field modelling Party, did not disappoint, with a strong on the website and in your inbox, furtherand palaeomagnetic studies in the turnout as usual to support local students technical meetings will be held monthlyTasmanides, and discussing implications who gave presentations on their recently at the Coopers Alehouse on Hurtlefor the interpretation of the middle crust completed honours projects. Square in the early evening, starting inin eastern Australia. Much discussion February with the Branch AGM, datefollowed, with more questions being Hugh Merrett, Gonghua Fan and TBA. If you are interested in joining theasked over a few reds. Thomas Lynch all did a brilliant job committee or holding a position on the presenting the background and results of Branch Executive, nomination forms willIn December, we held our quiz night. their chosen areas of study, with a very be sent out early next year. We invite allMany difficult and some not so difficult interesting variety of topics covering both Members, both SA/NT and interstate toquestions both geophysical and non- the petroleum and minerals industry. The attend our events, and of course any newgeophysical were asked and answered Branch thanks each of them for their Members or interested persons are also(well alright … mostly answered). A fun efforts and willingness to present, with very welcome to join us. For any furthernight and a good way to have our last special congratulations going to Thomas information or event details, please checkever meeting at the Rugby Club. Lynch who was awarded the prize for the ASEG website under SA/NT Branch the best presentation. After the official events and please do not hesitate to getAn invitation to attend NSW Branch business of the evening was complete in touch at [email protected] is extended to interstate and all the attendees were invited to stay and com.au, the email listed below, or oninternational visitors who happen to be in celebrate the festive season. (08) 8338 2833.town at that time. Meetings are generallyheld on the third Wednesday of each The local Branch held a number of Josh Sagemonth from 5:30 pm at the 99 on York successful technical talks, student events [email protected] in the Sydney CBD. Meeting notices, and other industry events in 2016 withaddresses and relevant contact details can numerous local, interstate and overseas Tasmaniabe found at the NSW Branch website. guest speakers, as well as a healthy social calendar, all with the added excitement ASEG Tasmania branch member AntonMark Lackie brought about by the ASEG-PESA- Rada will be giving a talk in the [email protected] AIG 25th Geophysical Conference and few weeks on the UAV (unpiloted aerial Exhibition. We would like to thank all vehicle or drone) geophysical surveyQueensland of our 2016 sponsors, the Department technology he has been developing. of State Development, Beach Energy, The system acquires magnetic as wellThe Queensland Branch of the ASEG Minotaur Exploration, Borehole Wireline as LIDAR data, and has been deployedis looking forward to another exciting and Zonge. Without their support we for UXO among other applications. Theyear. We plan to hold monthly meetings would not be able to hold such full presentation is likely to be in the CODESfeaturing local and international speakers programme of events for the local Conference Room at UTas. Exact time/as well as hosting our annual social membership. We will be in touch with all date details are yet to be confirmed;events. We are currently looking for our previous sponsors hoping they will Tasmania Branch members will bepeople to present to the Branch this year return again for 2017. Of course, if you or advised directly.and welcome interstate Members to our your company are not in the list above andBranch meetings. Our first meeting will would like to offer your support, please An invitation to attend Tasmanianbe held in February with details to be get in touch at the email address below. Branch meetings is extended to allposted on the QLD events tab on ASEG ASEG Members and interested parties.website. We will also be hosting the I would also like to thank the 2016 Meetings are usually held in theASEG AGM at the XXXX Brewery in Branch Committee, with special mentions CODES Conference Room, UniversityMilton on 10 April. All Members will be to Adam Davey our Treasurer and of Tasmania, Hobart. Meeting notices,10 PREVIEW FEBRUARY 2017

Branch newsASEG newsdetails about venues and relevant During 2016 the WA Branch hosted Australian Capital Territorycontact details can be found on the seven technical nights, three SEGTasmanian Branch page on the ASEG travelling lecturers and three workshops, The ACT Branch got in early for thewebsite. Interested Members and other and co-hosted the annual Golf Day. Christmas party season with a combinedparties should also keep an eye on the celebration with the local PESA Branchseminar programme of the University of We would like to thank our presenters: on 25 November. About 25 ASEGTasmania’s School of Earth Sciences, Todd Mojesky, Mark Baigent, Keith Members and partners enjoyed awhich regularly delivers presentations Fisk, Stanislav Glubolovskikh, Jeremy Mediterranean feast at the award winningof geophysical as well as general earth Cook, Lee Steven, Allan Trench, Olive Restaurant (ranked 5 out of 1026science interest. Please contact ASEG Joe Dellinger, Steven Constable and restaurants in Canberra!). The festivitiesTasmania Branch President Mark Duffett How-Wei Chen for presenting to our were tempered by serious geoscientificwith any queries. Members during the year. We would also discourse with a feature presentation by like to thank our workshop presenters: semi local structural geologist, TitusMark Duffett Serge Shapiro, James Gaiser and Jan Murray. The talk’s title, ‘Road [email protected] Francke. Finally, the WA Branch would Structure of the Southern Sydney Basin: like to extend its thanks to the committee Where Sydney gets its Water, The WorldVictoria members past and present for their Gets Coal and Your Route to the New assistance in planning and hosting the Year’s Fireworks’ nicely summarisesHappy New Year dear Members! busy programme through 2016. Titus’s ideas about the HawkesburyFirst of all I would like to thank the Sandstone, and the coalfields aroundVictorian Members who took the time The WA Branch’s technical nights were Campbelltown and Wollongong. I’mto answer the short survey that we run sponsored by the following companies: certainly taking a lot more notice whenlast December, your feedback was much Globe Claritas (Platinum), Resource I drive the Hume motorway betweenappreciated. Potentials, Western Geco, CGG, Atlas Sydney and Canberra. Unfortunately Geophysics, First Quantum Minerals everyone was having such a good timeOur last meeting was held on 15 Inc, GPX Surveys, Paradigm (Gold), that no-one remembered to take anyNovember, with our annual student night. Geosoft, ExploreGeo, and Southern photographs to record the happy event!Congratulations to Lachlan Hennessy Geoscience (Silver). The Branch could For those who couldn’t make it to the(PhD, RMIT) who won the 1st prize for not put together such a wide range of party, a more conventional Branchhis presentation, followed by Hamish technical activities without the support of meeting was held at GeoscienceStein (Masters, Melbourne University, our Platinum, Gold and Silver sponsors, Australia on 15 December. The meeting2nd prize) and Jesse Keegan-Osborne and we look forward to a long standing featured three short presentations.(Honours, Monash University, 3rd partnership with these companies. Laurence Davies gave an overviewprize). A big thank you to the other of the application of passive seismicparticipants as well, Elizabeth Grange At the AGM the Branch also recognised a techniques to Geoscience Australia’s(Masters, Melbourne University) and number of Branch Members with awards project areas, particularly for imagingAndrew Pearson (Masters, Melbourne including a Service Award (Kathlene cover thickness. Passive seismicUniversity). We closed 2016 with the Oliver), Student Awards (Tahlia Downes is a relatively new and innovativetraditional PESA-ASEG-SPE Christmas and Marko Zegarac), and 25 Year method being used for near surfacelunch. A large assembly gathered at the Membership Awards (Paul Wilkes, TonyKelvin Club to listen to Glen Nash from Weatherall, Lisa Vella, Laurence Roe, Tim Jones presenting his PhD work at the end ofExxonMobil recapitulating the history of Bill Robertson, Andrew Long, Audrey last ACT Branch meeting for 2016.discovery in the Gippsland Basin. Leonard, Jim Dirstein, Mike Dentith, Geoffrey Collis, Barry Bourne, andThe year 2017 will start on 22 February Andrew Bisset). Unfortunately not allwith a joint summer social event (details of the Award recipients could join usto be confirmed). on the evening to accept their awards. Congratulations to all!!Seda [email protected] The calendar for 2017 is filling up. The first events for 2017 include technicalWestern Australia night presentations on 15 February by Juerg Hauser (CSIRO) and 8 MarchThe WA Branch finished off 2016 with a by Shane Evans (Moombarriga).technical presentation by Allan Trench The Branch will also host the SEGon current trends in mineral economics, Distinguished Lecturer Paul Hatchellcombined AGM and Christmas Party on on 3 April. We are excited about the7 December. Allan drew from his vast programme of events planned for 2017experience in industry and on boards of and look forward to seeing our Membersdirectors to provide an insightful overview in attendance.of what successful exploration companiesdo, and how innovation drives our sector. Kathlene Oliver [email protected] FEBRUARY 2017 PREVIEW 11

ASEG national calendar ASEG newsexploration and it is good to see the High Performance Computing to process, The ACT Branch hopes everyone hadnational geoscience agency supporting model and deliver geophysical data and a great Christmas and summer break,development of acquisition processing products. The evening was rounded out and wishes everyone a fantastic andand interpretation methods. David by Tim Jones (ANU) presenting his prosperous 2017.McInnes gave an update on the Virtual PhD work on quantitative modellingGeophysics Laboratory, an exciting of mantle plumes to investigate the Ned Stolzproject tapping in to the vast power of heterogeneity of the deep mantle. [email protected] national calendar: technical meetings, courses and eventsDate Branch Event Presenter Time Venue2017 SA-NT AGM TBA 1730 Coopers Alehouse, Hurtle Square, Adelaide Feb QLD AGM TBA 1730 XXXX Brewery, Corner of Black Street and Feb Paten Street, Milton 1730–1900 TBA15 Feb WA Tech night Juerg Hauser TBA 99 on York Club, Sydney CBD15 Feb NSW AGM TBA TBA TBA22 Feb VIC Joint ASEG/PESA/SPE social event 1730–1900 TBA WA Tech night Shane Evans 1830–2030 XXXX Brewery, corner of Black Street and 8 Mar QLD ASEG AGM Various 1730–1900 Paten Street, Milton10 Apr TBA3 Apr WA SEG Distinguished Lecturer Paul HatchellTBA, to be advised (please contact your state Branch Secretary for more information).NEW 4QFDJBMJTUT
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IndustryNewsSafety in the air begins on the ground: a message to all stakeholders ofairborne geophysical surveysSafety in the air begins on the ground ensuring that their standards are passed related to the safe acquisition of airbornehas been IAGSA’s motto since its down to their airborne contractors. As geophysical data irrespective if theformation in 1995. IAGSA, the a service, IAGSA performs a Safety enquiry comes from a Member or not.International Airborne Geophysics Safety Review with all of our Active Members Furthermore, our ‘Contract Annex ForAssociation, is a Not-for-Profit member- to provide guidance and assistance Exploration Companies’ is also freelyrun global organisation dedicated to the towards the implementation of IAGSA’s available from our website (www.iagsa.safe operation of aircraft conducting recommended practices, document their ca) and we strongly encourage anygeophysical surveys. Through the active present level of compliance, and highlight company, whether an IAGSA Memberparticipation of our membership, IAGSA Notices of Difference between their or not, to take consideration of IAGSA’sdevelops recommended practices, serves practices and our recommendations. More recommended practices in your airborneas a centre for the exchange of safety and more of our Associate Members are geophysical survey planning andinformation, and acts as a repository for now including membership in IAGSA as append this annex to your next airbornespecialised statistics. a prerequisite in their survey procurement geophysics contract. process, and some are now requesting to On behalf of IAGSA for the safety of usBecause we are not a regulator, our see the most recent Safety Review before all,impact on our Members and the safety awarding a contract. Our Active Membersof the industry as a whole is based on operate in all parts of the world using a Lance Martinhow well we can influence our many wide variety of aircraft, and the ensuing COO, IAGSAstakeholders. Our Active Members conversation between Active Member, [email protected] directly engaged in airborne data client and IAGSA is where the real valueacquisition while our Associate Members in IAGSA’s existence lies. Joel Jansenare either service providers to their Director, IAGSAclients or end users of the data, including It is here that IAGSA’s motto of Lead – Geophysics, Anglo American plcmany of the world’s largest mining safety in the air begins on the ground [email protected]. Non-member stakeholders really rings true. Although an airborneinclude regulators, safety consultants, contractor’s flight operations are ofcommunities that give the airborne great importance to us, many of thegeophysical industry its license to operate, most important decisions that directlyas well as many mining- or exploration- impact the safe operation of an airbornecompanies that contract our Active geophysical survey are made during theMembers to perform work on their behalf. tendering process: the elevation-drape being requested, the type of aircraftIn these challenging economic times being provided, the safety culture of thefor the mineral exploration industry in contractor, and the competence of thegeneral, and for the airborne geophysical organisation including the crew memberssurvey industry in particular, we would who will fly the survey.like to remind all our stakeholders of theimportance in remaining focussed on one In the ideal world we would like everyof the core missions of IAGSA, which stakeholder in airborne geophysicsis to ensure that survey companies and to not only be a member of IASGAtheir clients alike follow a common safety but to wholeheartedly follow ourstandard. Safety considerations must recommendations as well. Regardless,always trump economic pressures and when it comes to IAGSA’s goal oftechnical factors. safe airborne-geophysical operations, membership is beside the pointWe know from experience that through because the onus of due diligence istheir constant focus on safety, many a responsibility of all stakeholders.of our Associate Members are able to IAGSA is available to answer questionspositively impact IAGSA’s goals by FEBRUARY 2017 PREVIEW 13

Where are they now? PeopleKate Holland: Winner of the 2009 ANU NewsPrize for Best Results in Geophysics W W W. S C I N T R E X LT D . C O MI completed a degree in Global andEnvironmental Science (with Honours)in 2011. My degree programme allowedme to benefit from the inter-disciplinarynature of Earth science throughout. Ipursued multiple scientific disciplines(physics, chemistry, biology and maths),repurposing them to solve problemsabout Earth, using geochemistry, andgeophysics – for which I won a prizein 2009. When it came to my Honoursyear, I chose a project that combinedchemistry and biology to study howforaminifera, a type of plankton, recordthe temperature and salinity of the oceansin which they live. The composition oftheir shells (mostly CaCO3) adjusts inresponse to changes in ocean conditions.Foraminifera are an important sourceof information for climate scientistswho wish to know how the temperatureof our oceans has varied in the past.That knowledge will allow us to makepredictions about our future oceans. First,however, the foraminifera needed to becollected and re-homed in the lab. I didthis over two summers, whilst SCUBAdiving, in the oceans off California andPuerto Rico – a fantastic time! I enjoyedmy honours year so much, and workedwith so many inspiring scientists, that Ichose to undertake a PhD continuing theresearch. This year I will complete myPhD and plan to continue investigatingour oceans, now as a fully-fledgedscientist.Kate [email protected] a foraminifer in the Atlantic ocean off Puerto Available in Australia from GeosensorRico, April 2014. Photo supplied by Bärbel Hönisch. Ph: 0407 608 23114 PREVIEW FEBRUARY 2017 www.geosensor.com.au

Conferences and eventsNewsSEG Annual Meeting, Dallas, October 2016Dallas, Texas, is known to me as the regional luncheons were reduced from Incoming SEG President, Bill Abriel, addresses theplace where President John F. Kennedy four to two by combining large areas SEG Council meeting.was assassinated on 22 November 1963. – the Americas and Europe/FSU wereI clearly remember this because it is combined, so were Asia/Pacific and Voting taking place in the SEG Council meeting.also the day of the first satellite relay Africa/Middle East. These combinationstelevision broadcast across the Pacific. blurred regional focus. amendment it will go to the MembersThat broadcast was made in preparation for consideration via a referendum.for the Olympic Games in Tokyo the At the end of the day the number of The major issue in front of this year’sfollowing year. On the morning of 23 delegates was 5560, which was a relief Council meeting was a motion to removeNovember (in Japan), I got up early to the Society as they made a surplus of the membership category of Associateespecially to watch the experiment on around $450 000. The exhibition hall was Member. The argument for was that ita 14-inch black-and-white cathode tube filled with 251 exhibitors, but we noticed would encourage young Members totelevision. The news of the assassination some regular exhibitors were missing. participate in SEG activities includingwas conveyed during that broadcast. The Delegates were talking about how voting and Committee membershiphistorical success of this experiment with long the low oil price would continue.a new communication technology was Despite the downturn in the industry itovershadowed by the historical news was apparent that research activities arecarried over the airwaves. Now Dallas growing strongly in geophysics. Aboutcan be reached by a direct Qantas flight 1100 papers were presented in the three-from Australia. day conference. There were 25 parallel sessions, nine of which were postersIn 2016, the SEG Annual Meeting was and e-posters. If you are a petroleumheld in Dallas amidst the US Presidential geophysicist, it would have been very hardelection. On the flat screen colour LCD to choose which session to go. Fortunatelytelevision in the hotel room, news, the convention centre was well laid outdebates and comments, some serious and and it was easy to move from sessionothers joking, about the election were to session. Nineteen workshops werevery frequently broadcast. In another held after the conference. SEG sold 675hotel the SEG conference organisers were tickets but 572 attended. Somehow 100worried that the number of delegates registrants did not show up! This may beand exhibitors at the Annual Meeting a reflection of the downturn.might not be as high as usual due tothe downturn of the petroleum industry The ASEG has three seats in the SEGprompted by the low price of oil. The Council. These seats are filled by theSEG conference usually attracts about President and two conference delegates.8000 delegates, and as many as 10 000 The role of the Council is to advisedelegates if held in Houston in a good the SEG Board of Directors. This isindustrial climate. Only three years ago usually done through amendments ofthe SEG conference in Houston was held By-Laws. Once the Council approves anin a bullish atmosphere, prompted by theincrease of shale gas production and the Koya, Tineka and Mr and Mrs Irwan Djamaludin in the ASEG booth.expansion of Texas port facilities for gasexport. At the opening ceremony the thenGovernor of Texas said: ‘If you come toTexas with a truck license, we will find ajob for you in a week’.The Dallas conference was different. TheSEG feared that the number of delegatesmight not reach 4000 and it would makeloss. The SEG had already been sufferingfrom the industry downturn and had laidoff a quarter of their staff in the earlierpart of 2016. We could see their costsaving efforts in the conference as well:the proceedings were all online - not evenavailable on a USB drive; the conferencebag was pretty modest with fewer sponsorlogos; the end-of-conference party wasnot included in the registration fee; thefrequency of shuttle buses between hotelsand the convention centre was reduced; FEBRUARY 2017 PREVIEW 15

and that it would reduce administrative Conferences and eventschores. The argument against was that Newsit would jeopardise the prestige of theActive Membership class and expose Downhole EM, MMR and IP Surveysthe SEG to risk of dominance by groups Surface EM and MMR Surveysof particular interest. The motion was High Power (100A) EM Surveysdefeated and this issue will not go to aMembers’ referendum. Surface IP Surveys including 3D Geophysical ConsultingOne important task associated with Instrument Repairrepresenting the ASEG at a SEGconference is meeting with SEG 4/133 Kelvin Rd, MaddingtonExecutives and Officers to discuss Western Australia 6109future cooperation. In past years theSEG has organised a separate meeting PO Box 3215, Lesmurdiewith representatives of each associated Western Australia 6076society, but the number of associated p. (08) 9291 7733societies seems to have become too large f. (08) 9459 3953and this year they decided to have onecombined meeting. The meeting seemed e. [email protected] crowded with nearly 100 people inthe room, but the atmosphere was more VORTEX GEOPHYSICSrelaxed than in an individual meeting.I managed to talk to the outgoing and www.vortexgeophysics.com.auincoming presidents, and the SEG officersfor publication, conferences, exhibitionsand education - all of them have dealingswith ASEG. During a chat with theincoming SEG President, Bill Abriel,I found that he would be in Australiafor three weeks in May and June as hiswife teaches part-time at the Universityof Technology in Sydney. I asked if hewould be interested in running an OzStepcourse during his stay. He was agreeableand the course will be held during hisvisit in late May to early June.The next AEGC Conference (equivalentof ASEG’s 26th Conference andExhibition) was promoted at theASEG booth and in the ExhibitionHall. The ASEG booth was locatedin a well exposed corner position inthe Exhibition Hall. We usually haveblow-up kangaroos at the booth, whichattract eyes of passers-by. Unfortunatelythe kangaroos were punctured at theAdelaide conference in August andwe could not get replacements. Manyvisitors came to look at the posters ofgeophysical maps of Australia. I sawsome friends from Australia, many ofwhom I have not seen for some time.At the ‘wrap-up’ meeting after theconference the SEG Officer reported that215 out of the 251 exhibitors (86%) re-booked their booths for next conference.This sounded an optimistic note for thefuture. The next SEG Annual Meetingwill be held in Houston from 14 to 19October 2017.Koya [email protected] PREVIEW FEBRUARY 2017

Geophysics in the SurveysNewsGA: update on geophysical survey progress from the Geological Surveysof Western Australia, South Australia, Northern Territory, Queensland, NewSouth Wales, Victoria and Tasmania (information current on 13 January 2017)Further information on these surveys is available from Murray Richardson at GA via email at [email protected] ortelephone on (02) 6249 9229.Table 1. Airborne magnetic and radiometric surveysSurvey name Client Project Contractor Start flying Line km Spacing Area End Final data Locality GADDS release AGL (km2) flying to GA diagram TBA management Dir TBA (Preview) 43 680 TBA TBAGawler Craton GSSA GA MAGSPEC Estimated by 240 240 200 m TBA 183: AugOodnadatta Airborne the end of 60 m 37 920 TBA 2016 p. 34 Surveys Jan 2017 EW 29 360 TBAGawler Craton GSSA GA Thomson Estimated 208 560 200 m TBA 183: Aug TBAOoldea Aviation by the end 60 m 11 000 TBA 2016 p. 34 of Jan 2017 EWGawler Craton GSSA GA Sander Estimated 161 386 200 m TBA 183: Aug TBALake Torrens Geophysics by the end 60 m 2016 p. 34 of Jan 2017 EW Estimated 250 m 184: Oct A contract is being drafted 60 m 2016 p. 23 by GACoonabarabran GSNSW GA TBA by mid-Mar ~50 000 EW TBA 2017Tasmanian Tiers MRT GA Up to an 200 m 11 000 National Collaborative TBA TBA estimated 60 m NS Framework Agreement TBA TBA between GA and MRT was 66 000 or EW expected to be executed in Jan 2017 National CollaborativeIsa Region QSQ GA TBA TBA Estimated 100 m 11 000 TBA TBA Framework Agreement 120 000 50 m EW between GA and GSQ executed on 13 Dec 2016TBA, to be advised.Table 2. Gravity surveysSurvey name Client Project Contractor Start No. of Station spacing Area End Final data Locality diagram GADDS release management survey stations (Preview) (km) (km2) survey to GA Approx.Stavely GSV GA Atlas 3 Dec 3465 200 m station TBA Jan The proposed survey TBA interval along 2017 covers parts of the Geophysics 2016 38 000 line 14 traverses Horsham, Hamilton, km Ballarat and Colac TBA Standard 1:250 000 map 13 801 sheets. The survey is to collect gravity stations Up to spaced 200 m apart on 14 50 000 separate road traverses.East Kimberley GSWA GA TBA 8 Oct Up to 2500 m line 82 690 3 Dec 14 Jan 2017 184: Oct 2016 p. 24 The survey covers the MedusaAirborne GA 2016 70 000 spacing 2016 Banks, Cambridge Gulf, Lissadell,Gravity Survey Gordon Downs, Mount Ramsay and Lansdowne Standard 1:250 k map sheet areasCoompana – GSSA Est 18 Regular grid of 2, 100 000 TBA TBA 183: Aug The contractor was expectedPACE area TBA Jan 1 and 0.5 km 2016 to commence acquisition on 18 p. 34 2017 Jan 2017Tanami- GSWA GA TBA TBA 2500 m line 110 000 TBA TBA The proposed survey area coversKimberley spacing the Billiluna (all), and parts of the Lucas, Cornish, Mount Bannerman, Mount Ramsay, TBA Noonkanbah, Lansdowne, Lennard River, Derby, Charnley and Yampi standard 1:250 k map sheet areas. The Quotation request closed on 31 Jan 2017 The proposed survey area covers the Anketell, Joanna Spring, Dummer, Paterson Range, Sahara,Kidson Sub- GSWA GA TBA TBA 2500 m line 155 000 TBA TBA TBA Percival, Helena, Rudall, Tabletop,basin spacing Ural, Wilson, Runton, Morris and Ryan standard 1:250 k map sheet areas. The Quotation request closed on 31 Jan 2017TBA, to be advised. FEBRUARY 2017 PREVIEW 17

Geophysics in the Surveys NewsTable 3. AEM surveysSurvey Client Project Contractor Start flying Line Spacing Area End flying Final Locality GADDS releasename management km AGL (km2) data to diagram Dir (Preview) Preliminary final data GA were supplied to GA onMusgraves – GSSA GA CGG 18 Aug 2016 8489 2 km; 16 371 The survey Expected 179: Dec 2015 30 Dec 2017PACE Area Aviation E–W lines completed on 24 p. 23 flying on Preliminary final data Nov 2016 were supplied to GA in 17 Sep 2016 Jan 2017Musgraves – GSSA GA SkyTEM 15 Sep 2016 7182 2 km; 14 320 The survey Expected 179: Dec 2015 Preliminary final dataCSIRO Area Australia E–W lines completed early Dec p. 23 were supplied to GA on flying on 2016 12 Jan 2017 13 Oct 2016Isa Region GSQ GA Geotech 8 Aug 2016 15 692 2 km; 33 200 The survey TBA 182: Jun 2016 Airborne E–W completed p. 23 flying on 4 Nov 2016TBA, to be advised.Exploring for the Future: North Australian Airborne Electromagnetic survey 2017Call for expressions of interest and • the proposed boundary for the infill AEDT Friday 24 February 2017 andsubscribers area is to be a simple polygonal shape should include a regular shaped polygon of the desired infill/extension area withGeoscience Australia is planning a • the number of line kilometres for each the corner coordinates listed in tabularprogramme of regional airborne infill area is to be no less than 200 in form.electromagnetic mapping between the totalTennant Creek and Mount Isa regions of Geoscience Australia is also seekingthe Northern Territory and Queensland. • before Geoscience Australia approaches assistance with borehole geophysicalFunded by the Australian Government’s the panel of AEM contractors, a signed induction conductivity logging fromExploring for the Future programme agreement with each subscriber is tenement holders in the survey area.(http://www.ga.gov.au/about/projects/ requiredpriority-projects/exploring-for-the-future), For more information please contact:the survey will consist of 20 km spaced • all infill data will be released at thelines over parts of the Newcastle Waters, same time. There will be no early Email TelephoneAlice Springs, Normanton and Cloncurry supply of any data to subscribers.1:1 000 000 standard map sheets, as [email protected] +61 2 6249 9482shown in the diagram below. Companies Geoscience Australia will select areas thatare invited to register their interest in the complement the objectives of the survey [email protected] +61 2 6249 9374project by submitting proposals to infill from the company proposals received forareas within the regional survey lines. infill/extension flying. Expressions of [email protected] +61 2 6249 9229 interest should be submitted by cobBy subscribing to a large regional survey,companies will benefit through Figure 1. Exploring for the future: proposed survey area for year one of the AusEM Programme, 11Geoscience Australia covering January 2017.mobilisation and stand-by costs as well asan expected reduction in the per linekilometre charge. Subscribers will alsobenefit from Geoscience Australia’squality assurance and quality controlprocedures to ensure that the datareleased are fit-for-purpose. Due to thesize of the survey over approximately830 000 km2, it may take six to twelvemonths from the completion of dataacquisition before data will be availableto subscribers. Data acquired undercompany subscription will be subject to a12 month confidentiality period fromreceipt of final data.Successful proposals must adhere to thefollowing criteria:18 PREVIEW FEBRUARY 2017



Canberra observedCanberra observed David Denham AM loads and stresses that will be placed on cent of installed capacity in the National Associate Editor for Government the infrastructure that supports it. Electricity Market will be rooftop solar. A major problem is that ‘in 2015, only [email protected] The NEM is changing as manufacturing 4.9 per cent of Australia’s national industry contracts and the service sector electricity generation came from windANU Energy Update expands. New technologies are changing generation, and 2.4 per cent came from2006; a timely event for the way energy is generated and delivered solar.’ There is a long way to go.Minister Frydenberg to consumers and Australia is committed to reducing its greenhouse emissions. A Because of these challenges, theThe ANU Energy Change Institute hosts series of recent events brought these issues Minister arranged for the COAGan annual forum on energy supplies. into focus. The Bass Strait cable between Energy Council to commission Dr AlanOn 29 November the Minister for the Tasmania and the mainland was severed Finkel, Australia’s Chief Scientist, toEnvironment and Energy gave the key and remained out of action for six months, examine what energy market reformsnote address and was followed by 12 the Heywood interconnector between are needed, together with a newother speakers. I am commenting on South Australia and Victoria failed, and a national approach to energy securitythree of these presentations. All of them storm in September 2016 caused several and reliability. A preliminary reportare available at http://energy.anu.edu. electricity pylons to collapse in South was released in December 2016: https://au/news-events/energy-update-2016, Australia. To make matters worse, the www.environment.gov.au/system/files/including the Minister’s talk. Hazelwood Power Station is expected to resources/97a4f50c-24ac-4fe5-b3e5- close in March 2017. The Minister pointed 5f93066543a4/files/independent-review-The venue and the timing was a good out that although it is an older power national-elec-market-prelim.pdf.opportunity for the Minister to provide station and a high emitter of carbon, itinformation on the Chief Scientist’s also provided 22 per cent of Victorian This report identifies some key questionsreview of Australia’s National Electricity operational electricity demand in 2015 and for the future of our energy system. OneMarket (NEM). is a significant source of electricity for of these is: South Australia.Frydenberg’s review of the National • What role should the electricity sectorElectricity Market He also reminded attendees that the play in meeting Australia’s emissions NEM was based on ‘a system powered reduction targets?Against a background of student activists by the big spinning machines of coal-chanting ‘Don’t burn dirty coal, keep it in fired generators - rotating 50 times a This set the cat among the pigeons andthe ground’ and ‘Keep our gas at home’, second which provide power at a steady some factions of the government objectedthe Minister gave what I thought was an frequency of exactly 50 Hz, and that stridently to this question because theexcellent review of the current situation coal is increasingly being replaced by the review may recommend a carbon tax or aregarding the NEM. intermittent, non-synchronous generation carbon trading scheme. As a result, Prime of renewables like wind and solar.’ Minister Turnbull abandoned a reviewThe NEM is the longest geographically of the Direct Action emission reductionconnected power system in the world, Furthermore, although ‘the costs of scheme. It just shows what a sensitiveextending from Port Douglas in solar PV and wind generation have political issue climate change is for theQueensland to Port Lincoln in South fallen further and faster than any pundits current government.Australia. It supplies all the states and predicted even five years ago, new-buildterritories of eastern and southern Australia solar and wind cannot compete yet with Anyway, if anyone wants to provide inputand generates around 200 terawatt hours existing coal fired power or gas on price.’ to the review the details can be foundof electricity annually, or about 80% per ‘However, a 2016 Australian Power on: http://www.environment.gov.au/cent of our electricity consumption. The Generation Technology report estimates energy/national-electricity-market-review.goal is to have a secure and affordable that wind and solar PV are cost- Submissions are invited until 21 Februaryelectricity system for households and competitive with new build generators and the report is due to be presented toindustry that is resilient and can handle the of equivalent emissions profiles, such as COAG in mid-2017. fossil fuel generators with carbon capture and storage, and that by 2030 wind and Mark Howden: Climate change: solar generation will be cost competitive an overview of the science, public with new build technologies generally.’ attitudes and the politics He also said that ‘Consumers, hungry for renewable energy, battery storage and Mark Howden from the ANU Climate more energy efficient technologies to Institute reviewed the current observations manage their household energy bills, are of climate change, particularly those that driving change in the electricity market affect Australia and the public attitude and leading to a more distributed grid. towards climate change here. There are now 1.5 million households in Australia with solar PV installed and According to Howden: over 1 million solar hot water systems and, by 2030, it is estimated that 24 per • 46% of Australians consider that climate change is happening and20 PREVIEW FEBRUARY 2017

Canberra observed human-influenced, 38% that it is made a dynamic presentation that hectares and the water should be at least happening but natural, and 8% say it is provides another way at looking at these 25 m deep. During the day, the solar cells not happening (what happened to the parameters. generate power for the grid and drive other 8% is not known) pumps to fill the upper reservoir. When• Most of the ‘not happening’ category If you visit the url: https://www.climate- the sun is not shining the water from the related to media ‘balance’ lab-book.ac.uk/spirals/, you can also upper dam falls to the lower dam and• There was an optimism bias (going to see other variables, such as Arctic Sea generates electricity. In theory, there are affect others more than me) across all ice. The figure below is taken from this hundreds of sites in southern Australia groups website and it’s certainly worth a look where these criteria can be met and that• And psychological distancing (problem as you can watch the changes month by could be developed. far away or in the future) across all month. groups In practice the costs to construct the• BUT climate adaptation was supported Andrew Blakers: 100% renewable infrastructure at each site and connect across the political divide (74% want energy it to the NEM might be prohibitive, but more action): linked to relevance, a prototype is being developed at the ethics/moral position and trust in the The critics of wind and solar energy abandoned gold mine at Kidston, near science/scientists. sources argue that you will always need Georgetown in Queensland. The Kidston a background supply of coal, nuclear or Solar Project involves a huge solar panelHow big the sample was and what can gas to provide the base load. Andrew array on the main tailings store and threebe done with these results to improve Blakers from the ANU Energy Change reservoirs based on the old mining pits.practical policy development is not clear. Institute tackled this argument head-on and proposed that off-river pumped hydro It is not clear how an elevation differenceWhat I did find interesting was the energy storage (PHES) could, and should, of 300 m is achieved at the site, orclimate spirals produced by Ed Hawkins be developed to cope with the no wind/no whether the evaporation losses willof the Climate Lab in the UK and shown sun situations. be prohibitive, but it is a worthwhileby Howden for temperature and CO2 practical test of the technique. Forlevels. The increases in temperature and The concept is simple. An array of more information go to: http://www.CO2 levels globally are well known, solar panels is built near two off-river genexpower.com.au/the-kidston-solar-but the presentation is usually restricted storage dams with a significant elevation project.html or have a look at Andrewto simple graphs of temperature or difference of greater than 300 m. The Blakers’ presentation.CO2 concentrations versus time. What surface areas should be at least 20Hawkins and his team have done is Sinodinos replaces Hunt as Minister for Industry, Innovation and ScienceFigure 1. The final image of the temperature spiral taken from http://blogs.reading.ac.uk/climate-lab-book/files/2016/05/spiral_optimized.gif and presented Prime Minister Turnbull has movedby Mark Howden. If you visit: http://blogs.reading.ac.uk/climate-lab-book/ Greg Hunt from Industry, Innovation andfiles/2016/09/co2.gif you can look at a similar presentation for atmospheric Science (IIS) to Health. Senator ArthurCO2 levels from 1958. Well worth a look, but the variation in CO2 levels is much Sinodinos is the new Minister for (IIS).smoother than the temperature curves, as you would expect. Sinodinos has a Bachelor of Commerce from Newcastle University, has worked in the Departments of Finance and the Treasury, and was a Director of Goldman Sachs JBWere investment bank before being elected to the Senate in 2011. Government Ministers have to agile and innovative. Greg Hunt took on the IIS Ministry in July 2016 and was moved to Health in January 2017. As the Prime Minister said: ‘The industry, innovation and science portfolio is critical to generating the jobs of the future and Senator Sinodinos’ extensive public policy experience over many, many years gives him a strong understanding of the key drivers of new sources of economic growth and how government can ensure that its policies deliver the innovation, the investment, the technology that will secure the future for our children and grandchildren.’ With endorsements like this we expect great outcomes from the new Minister. FEBRUARY 2017 PREVIEW 21

Canberra observedProposed areas for the 2017 Offshore Petroleum ExplorationAcreage Release1The 2017 Offshore Petroleum Exploration Table 1. List of proposed areas 23 March 2017, in line with the secondAcreage Release area nomination and for the 2017 Offshore Petroleum round of work programme bidding forshortlisting processes are now complete. Exploration Acreage Release this release. The areas are:There were 97 area nominations from21 companies received, which is similar Proposed areas • AC16-1 to 2.to previous years. Twenty-two areas • W16-1, W16-3, W16-10 to 11, W16-have been proposed for inclusion in Bonaparte Basin NT17-1, 2; W17-1 & 2the 2017 acreage release. Information 13, W16-15- to 16, W16-19 to 21.about the proposed areas is availableonline at http://www.petroleum-acreage. Bonaparte & Browse AC17-1,2,3,4 & 5; W17-gov.au/2016/2017-nominations and is Basins 3; WA 56-Rsummarised in Figure 1 and Table 1. Roebuck Basin W 17-4Bidding on the first work programmeround of the 2016 Offshore Petroleum North Carnarvon W17-5, 6 & 7Exploration Acreage Release closed on 8 BasinDecember 2016. In addition, 12 areas willbe re-released and bidding will close on Exmouth Plateau W 17-8 North Perth Basin W 17-9 & 10 Otway Basin V 17 2 & 3 Bass Basin T 17-1 Gippsland Basin V 17-1 NORTHERN QUEENSLAND TERRITORYWESTERNAUSTRALIA SOUTH AUSTRALIA NEW SOUTH WALES A.C.T. VICTORIA Proposed 2017 Acreage Release area TASMANIA Current title Scheduled Area boundary (OPGGSA 2006) SAA 16065-32Figure 1. Location of proposed area for the 2017 Offshore Petroleum Exploration Acreage Release.1All the information for this article was taken from the December 2016 issue of Australian Petroleum News, published by the Australian Government(http://us11.campaign-archive2.com/?u=8ed6f6a545e71ff832ce3e1af&id=d7455f9b32).22 PREVIEW FEBRUARY 2017

Canberra observedThe 2015 Offshore Petroleum Exploration Acreage Release finalised1Nine offshore petroleum exploration reprocessing PreSTM reprocessing of of new 3D seismic data, two explorationpermits have been awarded with a 3 000 km of 2D data and studies. The wells and geological and geophysicalminimum investment of A$475 million secondary work programme comprises studies, totalling A$61.8 million. Thereover the next six-years. These are 210 km² of new 3D broadband seismic were no other bids for this area.summarised below. data, mapping and one exploration well, totalling A$43.5 million. There were two Round two – awarded September–Round one – awarded March-June other bids for this area. November 20162016 AC/P60 (released as AC14-1) located WA-524-P (released as W15-8) locatedWA-521-P (released as W15-5) located in the Timor Sea approximately 300 km in the Northern Carnarvon basin has beenapproximately 250 km from the northeast offshore and 650 km west of Darwin, awarded to Carnarvon Petroleum Limited.coast of Western Australia, was awarded was awarded to Total E&P Holdings It proposed a A$3.4 million guaranteedto Carnarvon Petroleum Ltd. It proposed (Australia) Pty Ltd. It proposed an work programme including 250 km²a A$1.32 million guaranteed work A$8.70 million guaranteed work Broadband PreSDM reprocessing of 3Dprogramme comprising of 4 000 km of programme comprising geological data. The secondary work programme2D multi-client reprocessed data, 150 and geophysical studies, acquisition comprises of well planning and long leadkm of 2D seismic acoustic impedance or licensing of 700 km² of new 3D studies and one exploration well, totallinginversion and geological and geophysical broadband seismic data. The secondary A$26.3 million. There were no other bidsstudies. The secondary work programme work programme comprises geological for this area.comprises acquisition, processing and geophysical studies and oneand interpretation of 300 km² of new exploration well, totalling A$26.50 EPP46 (released as S15-1) located in3D seismic data and geological and million. There was one other bid for this the Bight basin has been awarded togeophysical studies, totalling A$3.57 area. Karoon Gas Browse Basin Pty Ltd. Itmillion. There were no other bids for this proposed a A$25.85 million guaranteedarea. AC/P61 (released as AC15-1) located work programme including acquisition approximately 600 km Darwin, has been or licensing of 5 000 km of new 2DWA-522-P (re-released as W14-1) located awarded to Finder No. 1 Pty Limited. It seismic, 2D gravity, magnetic andapproximately 400 km from Darwin, proposed a A$500 000 guaranteed work bathymetric survey data; reprocessingwas awarded to Woodside Energy programme comprising of 330 km² 3D existing 2D data; and acquisition orLtd. It proposed a A$13.39 million PreSDM seismic data reprocessing and licensing (and processing) of 2500 km²guaranteed work programme comprising geological and geophysical studies. The of new 3D seismic data. The secondaryof geotechnical studies, 2D seismic secondary work programme comprises work programme comprises geotechnicalinterpretation and acquisition and PreStack 200 km² of reservoir characterisation studies and one exploration well, totallingTime Migration (PreSTM) processing studies, geological and geophysical A$117.5 million. There were no otherof 1586 km² of new 3D broadband studies and one exploration well, totalling bids for this area.seismic. The secondary work programme A$15.25 million. There were no othercomprises 1500 km² of 3D Full Waveform bids for this area. WA-525-P (released as W15-14) locatedInversion studies and one exploration in the Northern Carnarvon Basin haswell, totalling A$18.92 million. There VIC/P71 (released as V15-2) located been awarded to BP. It proposed a A$10were no other bids for this area. about 200 km east of Melbourne, has been million guaranteed work programme awarded to Llanberis Energy Pty Ltd. including licensing, reprocessing andWA-523-P (released as W15-2) is It proposed a A$9.3 million guaranteed interpretation of 2300 km²of the Zeuslocated approximately 470 km from the work programme comprising of geological 3D survey plus other 3D surveys overnorthwest coast of Western Australia, was and geophysical studies, acquisition, the permit area. The secondary workawarded to Carnarvon Petroleum Ltd. It processing and interpretation of 550 km² programme includes one exploration wellproposed a A$2.83 million guaranteed of new 3D seismic data. The secondary and data analysis, totalling A$93 million.work programme comprising of 3D data work programme comprises acquisition, There were no other bids for this area. processing and interpretation of 1200 km²1All the information for this article was taken from the December 2016 issue of Australian Petroleum News, published by the Australian Government(http://us11.campaign-archive2.com/?u=8ed6f6a545e71ff832ce3e1af&id=d7455f9b32). FEBRUARY 2017 PREVIEW 23

Canberra observedOil price and drilling activity recover in 2016For the first time in eight years OPEC Table 1. Global consumption and production of oilagreed, in September 2016, to limit oilproduction to a range of 32.5 to 33 million Global consumption and production of oil in millions of barrels/day 2005–2016*barrels a day. This is down from anestimated 38 mbl/day produced in 2015. Year 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015Given that global consumption has Consumption 84.7 85.7 87.1 86.6 85.7 88.8 89.8 90.7 92.0 93.1 95.0increased consistently by about 1.2%per year from 2005 through 2015 (Table Production 81.9 82.5 82.3 82.8 81.2 83.3 84.1 86.2 86.6 88.8 91.71), and is expected to have reached96 million barrels in 2016, it is not *From BP Statistical Review of World Energy, 2016; note that 100 million bl/day is ~4.6 billion t/year. https://www.surprising that it didn’t take long for bp.com/content/dam/bp/pdf/energy-economics/statistical-review-2016/bp-statistical-review-of-world-energy-the oil price to increase after the OPEC 2016-full-report.pdf.decision. Numner of rigs per month blue data 4500 160 WT crude US$/bl cpi adjusted red dataAnd of course, when the price goes 4000 140up, exploration investment increases, 3500 120particularly drilling activity. Baker 3000 100Hughes has compiled the rotary rig 2500 80counts as a service to the petroleum 2000 60industry since 1944, when the Hughes 1500 40Tool Company began weekly counts 1000 20of US and Canadian drilling activity. 0In 1975 Hughes initiated the monthly 500international rig count. These counts are 0an important indicator, not only for thedrilling industry and its suppliers, but for 22222222222222222000000000000000001100010101001100068093742512140365.................11111111111111111the whole petroleum exploration industry. Figure 1. Monthly global operating rig numbers from January 2001–November 2016, takenThe most recent results plotted in from the Baker Hughes rig count (see: http://phx.corporate-ir.net/phoenix.zhtml?c=79687&p=irol-Figure 1 cover the period 2000 through rigcountsoverview). The oil price is the monthly spot price for West Texas crude (http://www.eia.gov/dnav/November 2016. As you would expect, pet/hist/LeafHandler.ashx?n=PET&s=RWTC&f=M) and the price has been adjusted to December 2016 USthere is a strong correlation between the dollars to correct for changes in the US consumer price index (http://www.bls.gov/cpi/cpid1503.pdf).oil price and the number of operatingrigs. It turns out there is a lag time 4000 Av monthly rig counts N America/world 2000-2016 0.8now of about four months between a 3500 0.7significant price change and the number 3000 0.6of rigs operating. In the early 2000s 2500 0.5the lag was sometimes as much as two 2000 0.4years. If nothing else the drilling industry 1500 0.3is now able to respond very quickly to 1000 0.2changes in demand. 0.1 500 0Canada and the US continue to dominate 0the rig numbers, probably due to thedemand for hydrofracturing, even though 2000the total number of rigs is declining. In 20012000 there were approximately 1500 rigs 2002operating each month in North America, 2003while in 2016 the number had dropped 2004about 620. Not only has the number 2005of rigs dropped, but the ratio of North 2006American Rigs to the world total has also 2007declined (Figure 2). This ratio remained 2008between 0.6 and 0.7 from 2000–2014, but 2009by 2016 the share had dropped to 0.4. 2010The Australian count in 2016 averaged 2011only five rigs per month; a huge fall from 20121980s when an average of over 30 rigs 2013were operating each month. 2014 2015There won’t be much more oil discovered 2016here unless more drills are working. Figure 2. Average monthly number of rigs operating globally (blue curve), for the period 2000–2016 and the ratio of North American rigs to global count (red curve).24 PREVIEW FEBRUARY 2017

Education mattersEducation matters It is a sad truth that in the present era Gary’s discussion of of compressed undergraduate courses Michael Asten few students of geophysics get to study quake magnitudes, Associate Editor for Education seismology. ranging from rumbles [email protected] Last year, during a collaboration we barely feel to those between Deakin, Melbourne and Monash which notionally split Universities on using seismometers for the unlikely task of detection of the earth, appear in the megafaunal bone beds, I asked Gary article below. Gibson to clarify for me the meaning of the many measures of earthquake 25th ASEG-PESA-AIG Emma Brand, Chair of magnitudes and, with tongue somewhat in cheek, I also asked for his comment on conference logo. the ASEG Education our 2016 ASEG conference logo. Gary is a Principal Research Fellow at Melbourne Committee, also brings us a review of University, and one of Australia’s most senior seismologists. the role of the Committee and advance notice of two forthcoming OzStep courses in our continuing professional education programme; with one seismic and one EM-inversion course, there is something for each of us to enjoy as we sharpen our skills.Earthquake magnitude 12?Gary Gibson An earthquake is the motion produced earthquake the total slip between the [email protected] when stress within the earth exceeds the blocks increases and the fault dimensions strength of a fault, which then fails, with (length, width, area) may increaseWe hear about very large earthquakes one side of the fault moving (slipping) slightly, so the fault may be capable ofwith magnitudes 10 or 12, especially relative to the other giving a permanent a slightly larger earthquake next time.from fiction writers and Hollywood, but displacement. The point on the fault The fault may eventually become thejust how large can an earthquake be? where the rupture starts is called the dominant fault within the locality, and earthquake hypocentre or focus, and the will be the mechanism for most of theEarthquakes vary widely in scale. The point on the earth’s surface vertically strain energy release within the vicinity.largest earthquake recorded (Chile, 22 above it is called the earthquakeMay 1960, (energy) moment magnitude epicentre. Earthquake size can be measured inMw 9.5) released about 106 times many ways, such as energy release,as much energy as Australia’s most Once started, a rupture can propagate fault rupture length, duration of motion,damaging earthquake of recent decades predominantly in one direction from the radius of perceptibility, and especially(Newcastle 1989, ML 5.6). Extending the hypocentre, so that the hypocentre may the level of ground motion recorded atscale, the Chilean Mw 9.5 quake released be at one end of the rupture (e.g. Nepal, a seismograph some distance from the1012 times as much energy as a very 2015, Mw 7.9). Alternatively, it can earthquake.small earthquake that is only felt within propagate in all directions so that thea couple of kilometres (ML 1.5) – such hypocentre may be near the centre of the Energy release is difficult to measureas minor movements in the Sydney basin. final rupture (e.g. Chile, 2010, Mw 8.8). because the proportion of energy releasedMore on the different units Mw and ML as heat and seismic ground motionis given below. Much energy is required to maintain the varies, the seismic wave radiation propagation, with most being converted pattern varies with direction depending to heat and some to seismic wave energy. on the orientation of the fault, and the The fuel maintaining the rupture is the absorption of seismic wave energy with available stored tectonic strain energy in distance varies with geology, leading to the volume surrounding the fault. If the uncertainties in attenuation of ground fault ruptures into an area without high motion with distance, especially for the stress (i.e. with low tectonic strain energy higher frequency motion experienced density), the rupture will slow and/or stop. from smaller earthquakes. As the tectonic deformation continues the Earthquake magnitude scales are defined strain, strain energy density and stress to characterise the size of an earthquake rebuild, and the weakest point on the using one of these measures, most fault is the likely location of the initial commonly a measure of earthquake rupture for future earthquakes. After each ground motion. FEBRUARY 2017 PREVIEW 25

Education mattersThese can include measures of motion All scales were defined to conform Aftershocks are often on the originalthat are permanent, such as the area, as closely to the Richter magnitude rupture or around the edge of the rupture,length, width or the slip that occurs ML as possible, but since each uses a thus delineating the rupture and allowingduring the earthquake. They can also be different measurement, the relationships estimates of area, length and width.measures of the transitory seismic wave are non-linear, and conversion plots or However, many aftershocks may be onmotion as recorded on seismographs, functions and range limits for magnitude smaller related faults and delineate thewith the wave motion measured as and distance are needed. Since these are surrounding volume that has experienceddisplacement, velocity or acceleration, different depending on local geology, stress change in the earthquake, ratherusually recorded as a function of time in local differences in methodology and than the main rupture itself. Althoughthree orthogonal directions (east, north practice have developed. relatively few earthquake ruptures canand up). This motion can be simplified be delineated, and these are mainlyby using parameters such as peak ground It might seem reasonable that to reduce only for larger earthquakes, they aredisplacement (PGD), velocity (PGV) or confusion, the magnitude should be used to determine relationships betweenacceleration (PGA), or alternatively using converted to a single defined value. magnitude and fault rupture parameters.parameters relating to the spectral content Modern conventions include the GSHAP(also using displacement, velocity or method where magnitude M is based The following table shows approximateacceleration, and three components). on ML, mb and Mw, over different empirical relationships between magnitude ranges (ML or mb depending magnitude and several parameters such asUnfortunately, the ground motion on distance for events below Mw 5.0, and rupture area, fault length and width, faultmeasurements possible vary greatly from Mw for those events larger than Mw 5.0), slip and rupture duration. Earthquakessmall to large earthquakes, and from near giving a scale that retains all past values. vary from simple one fault ruptures toto distant earthquakes. This has resulted very complex ruptures, some have simplein a range of different magnitude scales An alternative is a trend to converting geometry (e.g. approximating a circularfrom ground motion measurements that all magnitudes to Mw, although it is not plane rupture or a rectangular plane asare each applicable for certain magnitude easy to measure Mw values smaller than often used in theory) while most haveranges, and distance ranges. Mw 5.0, and certainly not less than Mw varying rupture outline shape or varying 4.0. This method also results in the need slip across the rupture. The aspect ratioFor example, the original Richter to re-compute millions of earthquake of a fault rupture can vary from length =magnitude, ML, is used for small magnitudes (mainly ML and mb) using width, to length = 10 times width orearthquakes recorded within 600 empirical conversion functions that will more, especially for large crustal faults.kilometres. This takes the logarithm to not be universally applicable.base 10 of the peak body wave (P or S) The values of area, length, width, slip orhorizontal ground displacement and Most earthquake hazard studies consider duration will usually be within the rangeapplies a simple empirically determined only earthquakes above Mw 5.0, as from half to double the quoted value,correction for attenuation that varies with damage from smaller events is rare, so a depending on the stress drop from thedistance. This depends on the properties conversion, if used, has little impact on earthquake, with a higher stress dropof local rock types, with unconsolidated hazard estimates. At this stage giving the giving smaller ruptures.sediments giving rapid attenuation with magnitude type and value as measured,distance, while hard crystalline rocks (e.g. without a conversion, is probably the best The slip value depends on faultAustralian Shield) give relatively little we can do. strength, and gives an indication ofattenuation with distance beyond inverse the deformation needed to trigger thesquare geometric spreading. If an earthquake is very shallow it earthquake. The rupture duration depends may rupture the surface. For some on fault properties that determine the rateThe body wave magnitude, mb, is used earthquakes, the surface rupture gives the at which the rupture propagates acrossfor moderate magnitude earthquakes total length of the fault, while for others the fault plane, usually at about threebeyond 2000 km, also uses ground the rupture may extend further at depth, kilometres per second.displacement and has a tabular distance so the surface rupture length is only acorrection that corresponds to the less fraction of the total length. However, The actual slip motion between the twovariable attenuation of waves through the most earthquakes do not rupture the sides of the fault at any point along themantle compared with the dominance of surface at all. fault is much slower, and is usually up tocrustal motion as used with ML. a couple of metres per second. At such A better way of establishing the fault a point the time between the start of slipA range of moment magnitudes Mw, length and width is to install a high- movement until the slip has ground toMww, Mwp, Mwc, etc are determined resolution seismograph network that will a halt will be measured in seconds forfrom long-period frequency spectra allow determination of precise locations larger earthquakes, and fractions of aused for moderate to large earthquakes. of aftershocks to an accuracy of one second for smaller earthquakes. This is aThe variation in spectral attenuation kilometre or less in longitude, latitude much shorter period than the total rupturein crustal rocks limits the use of this and depth. For this reason groups such duration along the fault as a whole, asmethod for nearby earthquakes, especially as Geoscience Australia and University described above. For larger earthquakes,smaller earthquakes with dominant high of Melbourne maintain boxed sets of by the time the slip finishes at one pointfrequency motion. seismographs ready for immediate on the fault, slip movement may have shipping and deployment when a initiated kilometres away, further alongIn addition, there are magnitude scales significant quake occurs on the continent, the fault.based on the duration of motion, MD, such as the Petermann Ranges (west ofand radius or area of perceptibility, MP, Uluru) earthquake of magnitude Mw 6.1 The table was empirically determinedused mainly for determining magnitudes on 20 May 2016 (the largest earthquake using earthquakes in the range fromof historical earthquakes. within Australia for 19 years). Mw = 4 to Mw = 8. Because of the26 PREVIEW FEBRUARY 2017

Education mattersTable 1. Approximate fault parameter values as a function of magnitude. zones are along the west coast of SouthExtrapolation to magnitudes higher than about Mw 9.5 requires faults larger America, the Tonga-Kermadec Trenchthan are currently available south of Fiji, the Sunda Trench south of Indonesia, and the large trenches inMoment Rupture area Typical rupture Fault slip Rupture Average the north-west Pacific (Aleutian, Kuril,magnitude (km2) size Length/20 000 duration number, Japan and Mariana Trenches). All knownMw Length/3 earthquakes larger than Mw 9.0 have 1 Length × width (metres) (seconds) World occurred on these subduction zones.4 10 (km × km) (per year)5 100 0.05 0.3 For plate boundary earthquakes, large6 1000 1×1 0.15 1 20 000 strike-slip earthquakes may rarely exceed7 0.50 3 2000 Mw 8.5, because of length limitations 10 000 3×3 1.5 10 200 along existing boundaries and especially8 because of rupture width limitations 100 000 10 × 10 5 33 20 imposed by the shallow seismogenic9 depths available. 1 000 000 30 × 30 25 170 110 50 × 20 The table can be extrapolated down to 10 000 000 50 333 0.05 smaller earthquakes, below magnitude11 100 × 100 0.0 and will give reasonable estimates 100 000 000 200 × 50 150 1000 0 (within half to double depending on stress12 drop). If we extrapolate to magnitude 12, 500 × 200 500 3000 0 then the values for magnitude 9 seem 1000 × 100 reasonable, but for magnitudes 10 to 12 0 the fault lengths and/or widths available 1000 × 1000 at plate boundaries are not enough to 5000 × 200 provide the tectonic strain energy needed. An Mw 12 quake implies a 10 000 km × 3000 × 3000 10 000 km displacement, comparable with 30 000 × 300 the Earth’s diameter of 12 742 km. 10 000 × 10 000 Perhaps the impact of a large object 300 000 × 300 from space may give such an event. Or, returning to the question Michaelarbitrary definition of the original faults are rarely much longer than 100 Asten asked me last year, a truly earth-Richter magnitude, it is probably just a kilometres, the typical maximum credible shattering ASEG conference might justcoincidence that a magnitude Mw = 4 earthquake is usually less than about do it!gives a 1 square kilometre rupture, and Mw 7.5.that there is a factor of 10 in rupture areafor each unit change in magnitude. Large subduction interface earthquakes may reach a little over Mw 9.5, butFor intraplate earthquakes within require very long subduction zones (overcontinents, where the seismogenic zone 1000 km), and deep subduction that canextends down to just tens of kilometres, give a rupture width extending down tousually just 20 to 30 kilometres, and about 300 km. The largest subductionThe ASEG Education Committee: what can we do for you?Emma Brand technical experts. In boom times our As I took up the role of chair of theASEG Education Committee Chair profession is in high demand and we are ASEG Education Committee late [email protected] very well compensated for our skills. year, stepping into the huge shoes left by During down times the first cuts are to Wendy Watkins, I began to think further2016 was a tough year, once again, for the exploration budget, which means our about what it means to be a practicinggeophysicists. If you weren’t personally once highly prized, well compensated geophysicist. Throughout my ten yearaffected by the cuts across the industry, skill set is no longer valued by our career in the oil and gas industry I’veI’m sure you will know plenty of friends industry. This leaves many of us in the interpreted seismic data and undertakenand colleagues that were. It’s not news unenviable position of having to fight it quantitative analysis, I’ve planned andto state that geophysics is a highly out against more and more candidates in drilled wells, I’ve worked on explorationspecialised profession. We are deep a smaller pool of roles, waiting for the prospects and on oil fields that have been industry to pick back up. producing for 50 years, I’ve planned and executed seismic surveys, I’ve managed The question that I posed to myself people, I’ve managed projects, I’ve during the uncertainty of the last several collaborated in multi-disciplinary teams. years was: what happens if my role is made redundant? In an industry with How many times have you been to a very few new roles and an uncertain dinner party and had to explain what it future, how do I ‘future proof’ myself? is that a geophysicist actually does? My How do I ensure that I have a skill set typical line is that we work out what that is mobile and flexible and, more is in the ground without having to dig importantly, if worst came to worst, a dirty big hole. That might be all well understood outside of my industry? and good over a cocktail but, if you had FEBRUARY 2017 PREVIEW 27

Education mattersto, how would you translate your deep, our Members. For instance, how do we So, I throw this question out into the etherspecialised skill set and incredible range determine topics for OzStep? How can and solicit your responses: what wouldof experiences into something that is we provide the support needed to our you be interested in seeing the ASEGrecognisable outside of our industry? Members to translate their skill sets Education Committee organise in 2017? outside of our industry? Should theThis year the Committee, consisting Education Committee ‘push’ OzStep Upcoming OzStep courses: ‘Reservoirof the wonderful, thoughtful and topics, or ‘pull’ topics that are requested Geophysics – Applications’, a one-dayexperienced crew of Jarrod Dunne, by Members or is needed by the industry? course by Bill Abriel will be heldMegan Nightingale, Chris Wijns and Can we do more to address upskilling at various locations in May. DougTim Dean will tackle the broad question recent graduates into the industry? And Oldenburg will also be giving a courseof how the ASEG Education Committee more importantly, what else might our on EM-inversion. Stay tuned for moreshould respond to our current resource Members be interested in? information.industry landscape in order to benefitSEG Distinguished Lecturer 2017: Paul HatchellGetting more for less: frequent low-cost seismic monitoring solutions foroffshore fieldsPaul Hatchell that we can observe production-induced the pros/cons of the various technologies changes in the reservoir after months to select the best option for a specificSummary instead of years. This creates a demand field. Some results of applying these for frequent seismic monitoring to better techniques to offshore fields will beTime-lapse seismic reservoir surveillance understand the dynamic behaviour of discussed.is a proven technology for offshore our fields. Increasing the frequencyenvironments. In the past two decades, of seismic monitoring will have a Biographywe have seen this technology move proportionate cost implication, and afrom novel to necessary and enable us challenge is how to design a monitoring Paul Hatchell joined Shell in 1989 afterto monitor injection wells, water influx, program that maximises the overall receiving his PhD in theoretical physicscompaction, undrained fault blocks, and benefit to the field. from the University of Wisconsin. Hebypassed reserves. Value is generated by began his career at Shell’s Technologyinfluencing the management of our field Reducing individual survey costs is Center in Houston and worked on aoperations and optimising wells to reduce important to enable frequent monitoring. variety of research topics includingcost, accelerate production, and increase Several techniques are considered for shear-wave logging, quantitative seismicultimate recovery. lowering these costs such as: amplitude analysis, and 3D AVO applications. Following a four-year oilSignificant advances in technology • Reducing the number of shots and/or and gas exploration assignment in Shell’sare improving the quality of our data. receivers to minimise offshore vessel New Orleans office, Paul returned toErrors in acquisition repeats are nearly time. This includes shooting targeted Shell’s technology centres in Rijswijkeliminated using permanently installed (i4D-style) surveys on a frequent basis and Houston where he is currently asystems or dedicated ocean- bottom in between full-field surveys that are member of the Areal Field Monitoringnodes. We now routinely obtain surveys acquired infrequently. team and Shell’s principal technicalwith such a high signal-to-noise ratio expert for 4D reservoir surveillance. • Use of smaller source arrays towed by His current activities include developing less-expensive vessels. improved 4D seismic acquisition and interpretation techniques, seafloor • Semi-permanent ocean-bottom nodes deformation monitoring, and training the that can be left on the seafloor for next generation of geoscientists. multiple on-demand surveys. Australian schedule: • Time-lapse VSPs that use permanent distributed acoustic sensors (DAS) in 3 April 2017 Perth University of well bores. Western Australia • High-resolution 4D surveys that 3 April 2017 Perth ASEG WA monitor shallow reservoirs cost Branch meeting effectively using low-cost vessels towing arrays of short-streamer cables (e.g. P-cable). There is no single solution that works for every field, and we need to understand28 PREVIEW FEBRUARY 2017

Environmental geophysicsEnvironmental geophysics Mike Hatch Welcome readers to this issue’s aquifers and characterise them. Most of Associate Editor for column on geophysics applied to the the signal in any electrical survey just Environmental Geophysics environment. I was having trouble doesn’t penetrate very far into [email protected] coming up with interesting material for conductive ground, and the contrasts this issue (think about thinking about between where there is water that is this over the Christmas holidays) and easy to extract and where it isn’t can thought that I would try to crowd- be is very subtle. Well, Dave Walsh of source some ideas from some of my Vista Clara has been doing some testing friends and acquaintances in the field of in some areas that are pretty saline environmental geophysics – my thought and has been finding that NMR can do was to write about some of the holy a great job of separating the aquifers grails… from the aquitards and characterising hydrogeologic properties in these One of those holy grails is what to do challenging environments. Here is Dave’s in highly saline environments to identify story.Identifying and characterising aquifers in saline environmentsDave Walsh resource for domestic and industrial water been successfully employed in highlyVista Clara Inc. supplies (https://gemcenter.stanford.edu/ conductive brine and petroleum [email protected] research/aquifer-characterisation-indian- by the oil and gas industry for decades; wells-valley-california-using-geophysical- this ability is now being extended to useMotivation for this work lies in the fact techniques). In all of these settings (most in groundwater surveying.that the world’s groundwater supplies of which are likely to be high in TDS) itare getting more and more stretched, and is important to know the properties and When a NMR logging tool is immersed inthere is increased need for non-potable location of the aquifers – which is hard an electrically conductive fluid and porouswater for industrial and commercial use. to visualise using standard geophysical medium, the transmitted and received RFAdditionally, in situ mining operations, techniques. fields are affected via electromagneticwhere mineral resources dissolved in skin effects (as are inductive techniques),saline groundwater are extracted through Geophysical methods based on nuclear resulting in some reduction in fieldproduction wells, are increasingly magnetic resonance (NMR) are being intensity. This reduction, if unaccountedcommon worldwide (Beverley and tested and used for saline aquifer for, can lead to underestimation of waterHoneymoon are both examples of in investigations because they can provide content and porosity measurements. Forsitu uranium mines in South Australia). direct and reliable estimates of key example, Table 1 shows the NMR waterImportant mineral resources that are aquifer properties, including how much content measured by a typical smallcommonly extracted through in situ of the water at a given location is tied diameter NMR logging tool (Javelinmining include uranium, gold, lithium, up in fine grained material (i.e. is bound) JP238, Vista Clara Inc.) in fresh, brackishpotash and copper. In areas where and how much of it is mobile, leading to and saline water. The results indicate thatfreshwater resources are scarce, such as the ability to make high quality estimates using a fresh water calibration, there arein the China Lake basin in the southern of hydraulic conductivity, even in cases negligible effect on detected water contentCalifornia desert, water managers are where the groundwater is very electrically in brackish water with electrical resistivityincreasingly investigating deeply sourced conductive. NMR logging tools have of 0.5 ohm-m (2000 mS/m). A moderatebrackish groundwater as a potential Table 1. Experimentally measured effects of electrically conductive water on the NMR-estimated water content of a Javelin JP238 NMR logging tool. Values are derived using fresh water calibration values Water content measured by NMR Operating Diameter of cylindrical Fresh water Brackish water Saline water (0.1 frequency NMR sensitive shell (160 ohm-m) (0.5 ohm-m) ohm-m) 432 kHz 21 cm 100% 96% 75% 365 kHz 23 cm 100% 98% 75% 305 kHz 26 cm 100% 100% 73% 248 kHz 30 cm 100% 100% 79% FEBRUARY 2017 PREVIEW 29

effect on estimated water content is Environmental geophysicsobserved in saline water at 0.1 ohm-m(~10 000 mS/m) – remember that the Helpingocean is about 0.2 ohm-m (5000 mS/m). to targetNMR relaxation times, used to determine yourpore size and permeability are generally resourcesunaffected by the increase in salinity. Next time you need a survey, call Zonge.In practice, the effect of conductive † WUGQWT high powered systems andwater in earth formations is lower thansuggested by Table 1, because the latest technology for:electrically conductive water fills only a - surface 2D and 3D IP/EM/NanoTEM/CSAMT/AMT/NMRfraction of the volume between the tool - downhole IP/EM/MMR/NMR † GZRGTKGPEGFUCHGVGCOUKPCP[NQECVKQP accurate inversion of water † GH¿EKGPVUWTXG[FGUKIP content and other aquifer † SWCNKV[FCVCUGEQPFVQPQPG properties can be realised † JKIJN[TGURQPUKXGUGTXKEGand the NMR sensitive zone, so the bulk Call Zonge today +61 8 8371 0020electrical conductivity is much lower than e [email protected] the fluid alone (Archie’s Law). No w zonge.com.auconductivity corrections are applied tothe data in Table 1 and the accuracy in Electrical geophysical solutionsvery conductive formations can be further Resource exploration, environmentalimproved if necessary using a calibration and geotechnical applicationsof the tool in a brine tank.It is also well known that an electricallyconductive earth affects the depthof investigation for surface NMRmeasurements. Again, as long as theelectrical conductivity structure of thesubsurface is known (via electricalresistivity or induction surveys), the effectof the electrically conductive earth on themagnetic field patterns can be accuratelymodeled and accurate inversion of watercontent and other aquifer properties canbe realised (Weichman, 2000).An example of the use of NMRgeophysical measurements to characterisea saline aquifer system was demonstratedat a groundwater investigation site atLeque Island, in western Washington,USA. This site is an agricultural fieldthat was previously reclaimed frommarshland, adjacent to Puget Sound(an inland saltwater body). The upper20 m of the subsurface consists ofinterbedded, unconsolidated sediments,varying from sand and gravel to silt andclay. Groundwater samples obtainedfrom shallow monitoring wells at the siteranged from relatively fresh to brackish,with electrical conductivity measurementson groundwater samples ranging from250 mS/m (4 ohm-m) to 2500 mS/m (0.4ohm-m). Figure 1 shows a collocateddirect push EC measurement (Figure1a) and direct push NMR measurementusing a JP238 NMR logging probe(Figure 1b–e). The NMR measurement(Figure 1b) and the NMR derived aquifer30 PREVIEW FEBRUARY 2017

Environmental geophysicsproperties (Figure 1c–e) clearly indicate Figure 1. Comparison of direct push electrical conductivity (a) and direct push NMR measured aquiferthree distinct high permeability zones properties (b – e) at a site with brackish and saline groundwater, Leque Island Washington. The directcorresponding to well sorted sands and push EC log is dominated by the conductivity of the groundwater at this site, and hence provides littlegravels, denoted as zones 1, 2 and 3. The indication of the existence of the three high permeability zones. The direct push NMR log clearly indicatesNMR data in these zones were used to the presence and extent of three high permeability zones and provides quantified estimates of bound andderive quantitative estimates of hydraulic mobile porosity and hydraulic conductivity.conductivity that compared well to directhydrologic measurements (Knight et al., Figure 2. 2D electrical resistivity inversion, Leque Island Washington, USA, 2013. The electrical resistivity2016). In contrast, the direct push EC log measurements are dominated by the conductivity of the groundwater below 5 m, and hence indicate little(Figure 1a) shows much less correlation variability below 5 m.with aquifer properties and permeablezones. The EC log does clearly showthat the groundwater transitions fromrelatively fresh above 5m, to relativelysaline below 5 m.In addition, 2D surface electricalresistivity (ERT) and 1D and 2D surfaceNMR data sets were collected alongtwo parallel transects at this site. TheERT inversion, shown in Figure 2, (thedirect push EC and NMR measurementsshown in Figure 1 were collected onthis transect), shows that this site isquite conductive, with some correlationbetween the slightly higher resistivities atthe surface and the uppermost permeablelayer between 3 m and 7 m (if you reallysquint at the section). The 2D surfaceNMR inversion (Figure 3), collected alonga transect 100 m south of the ERT line,indicates a clear and laterally continuousaquifer zone between depths of 3 m and7 m, and a lower, laterally discontinuousaquifer zone at a depth of about 15 m.There is no question that there areshortages of drinkable water worldwideand that we need to make better useof the various qualities of groundwaterthat are available to us. NMR mayoffer a method to better characteriseand delineate those groundwaterresources that have been previouslyconsidered to be less than desirableand are also (therefore) hard todelineate.References Figure 3. 2D surface NMR inversion, Leque Island Washington, USA, 2013. The 2D surface NMR inversion clearly indicates the presence of a laterally continuous upper aquifer at a depth of about 5 m, and aKnight, R., Walsh, D. O., Butler, Jr., J. J., laterally discontinuous aquifer at a depth of about 15 m. Grunewald, E., Liu, G., Parsekian, A. D., Reboulet, E. C., Knobbe, S., and Barrows, M., 2016, NMR Logging to estimate hydraulic conductivity in unconsolidated aquifers: Groundwater, 54(1), 104–114. doi:10.1111/ gwat.12324Weichman, P. B., Lavely, E. M., and Ritzwoller, M. H., 2000, Theory of surface nuclear magnetic resonance with applications to geophysical imaging problems: Physical Review E, 62(1), 1290. FEBRUARY 2017 PREVIEW 31

Minerals geophysicsMinerals geophysics In 2016 CSIRO Mineral Resources mineralising processes is one of the ways completed the Uncover: Cloncurry into the future for mineral geophysics. project and formally presented their results. To me, the idea that systematic Jim Austin and his colleagues at and multidisciplinary measurements on CSIRO have summarised some of their critically selected drill-core and hand methodologies and findings (with an specimen samples can be extrapolated to emphasis on mineral geophysics) for add to the understanding of district scale this edition of Preview. I invite you to read on. Terry HarveyAssociate Editor for Minerals geophysics [email protected] knowledge from structural, geochemical and petrophysicalanalyses at sample to regional scales: new insights into the Mount IsaEastern SuccessionJim Austin, Ben Patterson, John Walshe and Michael GazleyCSIRO Mineral ResourcesJim Austin of the Queensland Government’s that led to formation of the [email protected] Industry Priorities Initiative. The funds styles of mineralisation of the Cloncurry gave CSIRO Mineral Resources the District, within the architectural andBackground opportunity to work with the Geological geodynamic framework of the Mount Isa Survey of Queensland (GSQ) and Eastern Succession.The Uncover: CLONCURRY project industry partners, including: Minotaur,was funded in 2015 by Round 3 MIM-Glencore, Exco-Copperchem, CST, The techniques utilised can be Sandfire, Hammer Metals, Red Metal summarised in Figure 1, and include and Chinova, in developing mineral petrophysical analysis (e.g. density, systems based exploration in the Mount remanent magnetisation, magnetic Isa Eastern Succession. The aim was susceptibility, anisotropy of magnetic to undertake integrated petrophysical susceptibility (AMS)), and mineral and geochemical/mineralogical micro- mapping techniques (e.g. micro X-ray characterisation of deposits across the fluorescence (μXRF), rapid scanning Cloncurry District, and to use those electron microscopy (SEM) and micro data to better understand the structural, X-ray computed tomography (μCT), and metasomatic and metallogenic processes hyperspectral mineral mapping).Figure 1. Samples obtained for petrophysics were subjected to suite of geochemical and mineralogical analyses, and utilised for various mineral mappingtechniques (e.g. micro-magnetic field mapping, hyperspectral mineral mapping and X-ray micro-tomography).32 PREVIEW FEBRUARY 2017

Minerals geophysicsFigure 2. Petrophysical analyses were used to constrain deposit/prospect scale modelling of specific mineralisation styles, and also to constrain transformationsof the magnetic field.A strength of this integrated, multi- fundamental insights into both the spatial the Williams Batholith), and associateddeposit approach is the creation of an and temporal relationships between metasomatic events. The majority ofinternally-consistent dataset of samples alteration and mineralisation, the tectonic hydrothermal mineral deposits formedanalysed in a consistent manner. This evolution of the Cloncurry District is from ca 1525 to 1500 Ma, in conjunctionfacilitates direct comparisons between considered in this context. These analyses with several different metasomaticdeposits, and enables application of illustrate that the Cloncurry mineral overprints, e.g. sodic-calcic (SWAN),insights gained at the deposit scale, system is long-lived, comprising several magnetite-apatite (Canteen, E1), potassicresulting in a better understanding of the mineralising, orogenic and metasomatic (Ernest Henry), magnetite-barite-fluoritemineral system as whole (e.g. Figure 2). events that are often temporally inter- (Monakoff, E1), calcic (SWAN, Mt related, and which overprint each other Colin), and chlorite-hematite-pyriteAMS data were obtained for at least one in a variety of ways, to form disparate (Ernest Henry, Kalman, Merlin, Canteen).specimen from almost every sample obtained deposit styles. In the most simplistic In many cases deposits show evidencefrom 17 deposits and prospects across the terms, the mineral system was pre- of two or more styles of mineralisation,Cloncurry District, possibly constituting the conditioned by early (ca 1650 Ma) e.g. sedex + skarn (Maronan, Artemis),only such dataset compiled across an entire input of large volumes of Fe plus both sodic-calcic + calcic (SWAN), sedex +mineral system ever collected. Cu–Au and Pb–Zn-rich mineralisation magnetite-barite-fluorite (Monakoff, E1) in a syn-depositional exhalative setting. and skarn + magnetite-apatite + chlorite-AMS data are used to quantify structural During D2 (ca 1590–1570 Ma) peak pyrite (Canteen).fabrics within the mineral system, and temperature and strain conditions (e.g.are used to identify potential structural 630 ± 50 °C and 8 ± 2 kbar at Artemis), Strain conditions, structures, magmaticcontrols. In many cases it is possible to there was some remobilisation of metal systems, fluids and heat sources varied indifferentiate fabrics within different parts within the Cloncurry mineral system, magnitude and focus through time, andof the system, e.g. host rocks, mineralised via partial melting, metamorphic fluids therefore interacted in different ways tozones, and overprinting relationships. It and/or “skarn” formation. However, form a range of different deposit stylesis also possible to identify fabrics caused the relatively hot, ductile conditions (Figure 3).by re-activation of pre-existing structures, prevented the formation of large-scaleas well as extensional fabrics. The permeable fluid pathways, and this, Geophysical expressions of thestructural insights provided by the AMS together with a relative lack of magmatic Cloncurry Mineral Systemmeasurements provide a fundamental fluid sources, was not conducive to theinsight into both the spatial and temporal formation of hydrothermal deposits. The geophysical response of a mineralrelationships between deformation, Conditions became more favourable system is a function of the structural andalteration and mineralisation, allowing us during the late history of the Isan the geochemical development within theto temporally relate structural development Orogeny. During the later history (i.e. system. In this case, since we have usedto metasomatic and mineralising events post-D4), strain conditions transitioned techniques that mainly deal with magneticacross the Cloncurry District. from ductile to brittle, and the kinematics properties, the main geochemical/ gradually switched from shortening mineralogical events/processes of interestIntegrated structural, metasomatic ± transpression (D2–D4), to strike-slip pertain to the precipitation of magnetiteand metallogenic history of the (D5) and then to post-Isan extension at and pyrrhotite, plus hematite and pyriteCloncurry District ca 1500 Ma. This orogenic switch is (due mainly to their high densities) and coincident with intrusion of multiple economic sulphides (e.g. chalcopyrite,Since the structural data provided voluminous phases of felsic magma (e.g. sphalerite, galena). This is the first timeby the AMS measurements provide FEBRUARY 2017 PREVIEW 33

Minerals geophysicsFigure 3. Schematic highlighting the different ingredients of the Cloncurry mineral system, which which are related to redox and/orcombine in different ways to form a variety of different deposits styles across the district. IOCG = iron overprinting. Assemblages within IOCGsoxide copper-gold; QF = quartzofeldspathic. in general sit on a spectrum, from highly reduced to highly oxidised (Figure 4).any study has brought together so much barite). Any combination of these Oxidised assemblages contain hematite,petrophysical data from so many different minerals can be associated with high no pyrrhotite, but typically pyritestyles of mineralisation across a mineral densities. High magnetic susceptibilities and variable magnetite. Intermediatedistrict, and the results provide important (and hence high amplitude magnetic assemblages are typically magnetite-constraints for future exploration anomalies) are invariably associated with rich, and can contain pyrrhotite and/for various styles of mineralisation coarse magnetite, whereas monoclinic or pyrite. Reduced assemblages areundercover. The deposits studied have a pyrrhotite is associated with moderate typically pyrrhotite dominant, contain nowide variety of petrophysical properties, magnetic susceptibility and high hematite, but often do contain magnetite.primarily dictated by the relative contents remanence (and potentially unusual Our observations suggest that hexagonalof magnetic minerals (e.g. magnetite, magnetic anomalies). Hematite is only (non-magnetic) pyrrhotite is typicallymonoclinic pyrrhotite, hematite) and other weakly magnetic. associated with galena and sphalerite (innon-magnetic minerals (e.g. hexagonal sedex/BHT deposits), whereas magneticpyrrhotite, pyrite, galena, sphalerite, Many specimens contain mixtures of pyrrhotite is more typically associated different Fe-oxide and sulphide phases, with Cu prospects (in hydrothermal deposits). The deposits and prospects assessed by this study have a large range in magnetic susceptibility, from essentially negligible (e.g. 10–6 SI) to 2.1 SI (Figures 5, 6). In many cases high densities are correlated with high magnetic susceptibilities (e.g. Figure 5), and in most of these cases the dominant dense/susceptible mineral is magnetite. For the most part this is coarse grained, multi-domain magnetite, which does not retain significant, or stable remanence. High densities correlated with moderate susceptibilities are in many cases due to pyrrhotite. High densities and low susceptibilities are in many cases due to hematite and/or any of theFigure 4. Synthetic models of the El Dorado deposit, Tennant Creek (based on Austin and Foss, 2014), which contain different proportions of Fe-oxide and Fe-sulphide minerals, based on their Redox state. All the mineral assemblages have comparable density, but the different redox states have very different geophysicalexpressions.34 PREVIEW FEBRUARY 2017

Minerals geophysicsFigure 5. Plot of magnetic susceptibility vs density for ore samples from deposits/prospects assessed in are dominated by coarse MDthis study. (multidomain) magnetite, e.g. Osborne, SWAN. 2. Deposits with high density, high susceptibility, and moderate Q are pseudo single-domain magnetite-rich (possibly indicative of sedimentary origin), e.g. Cormorant, Maronan. 3. Deposits with high density, low susceptibility, and high Q are rich in monoclinic pyrrhotite, e.g. Cormorant, Canteen. 4. Deposits with high density, low susceptibility, and moderate Q are rich in metamorphosed hematite, e.g. Monakoff West BIF. 5. Deposits with high density, low susceptibility, and low Q may contain hexagonal pyrrhotite and/or sphalerite, galena, pyrite and hematite, with a relative absence of magnetite. Comprehensive reports are available for all 16 individual deposits and prospects across the district, as well as several summary documents. For further information contact [email protected] or [email protected]. Reference Austin, J. R., and Foss, C. A., 2014, Understanding iron oxide copper-gold (10CG) magnetic targets from the inside out: case studies from northern Australia: Annual Geoscience Exploration Seminar (AGES), 18–19 March 2014, Alice Springs.Figure 6. Plot of the ratio of NEM to magnetic susceptibility (Q, Koenigsberger Ratio) vs magnetic Jim Austin is a structural geologistsusceptibility for ore samples from deposits/prospects assessed in this study. and geophysicist whose main interest is in the application of magneticother sulphide minerals. The various possible that targets can be mis-modelled methods to mineral exploration. Priordeposits have a range of natural remanent due to their magnetisation being different to joining CSIRO he worked withmagnetisation (NRM) intensities from to the Earth’s local magnetic field. the Predictive Mineral Discoverynegligible up to mean values of 450 A/m, CRC, for the Encom-Mapinfowith associated Koenigsberger ratios of In terms of petrophysical properties Geoscience Consulting Group, andup to 130 (Figure 6). Deposits that have there are several recognised also as an exploration geologist inhigh Koenigsberger ratios are usually associations: Broken Hill, the Mount Isa Inlier,dominated by monoclinic pyrrhotite as Papua New Guinea and the Thomsonthe magnetic phase. Where monoclinic 1. Deposits with high density, Orogen. In his current role at CSIROpyrrhotite is the dominant phase it is high susceptibility, and low Q he is focussed on understanding the geophysical properties of Iron Oxide Copper-Gold (IOCG), Sedex, BHT (Broken Hill Type), BIF (Banded Iron Formation) and Magmatic Ni-Au-PGE systems, partnering with exploration companies around Australia. FEBRUARY 2017 PREVIEW 35

Seismic windowSeismic window Michael Micenko Figure 2. Close up of the channel-like featureAssociate Editor for Petroleum just above the strong P reflection that can be seen in Figure 1. [email protected] seismic attributes Figure 1. Pseudo-relief (centre) compared to section showing the detail and multiple seismic data (left) and RMS amplitude (right) channel fill events.A recent upgrade of my seismic calculated over an 18 ms window. The pseudo-interpretation software not only had relief enhances the channel-like feature circled. The Having reviewed this attribute twothe usual bug fixes or enhancements, it data are from the Jackson Field, Queensland. questions spring to mind:also came with a new seismic attributecalculator. ‘Great’ I thought, ‘all I need tends to enhance high amplitudes and Are there too many seismic attributes?is another attribute to add to the ever pseudo-relief certainly does that and it Is this one any better than the others?increasing list’. But this one was differentbecause I had never come across it before Are there too many seismic Being a fence sitter my answers are bothand had no idea what it did or how it attributes? yes and no. Yes, there are too manyworked. Originally called ‘tecva’ this is attributes to run them all on each dataseta fairly old post stack attribute that was appears to have improved resolution. and no, this one is no better than thedeveloped in Brazil in the early 1980s. Figure 2 is a zoom into a channel-like others. But it worked at the time and mayThe implementation I have now calls it feature visible on the pseudo-relief be useful in particular situations, which‘pseudo – relief’ and in an attempt to is the case for most seismic attributes.learn more about it I found a copy of Interpreters have access to manya paper explaining how it is calculated hundreds of seismic attributes on their(Bulhoes, 2005). It’s not an easy paper desktops (Figure 3 is a compilation ofto read because it’s written in Portugese, just some of the edge detection attributesbut non Portugese speakers can get the available). While we may not have timegeneral gist by feeding each paragraph to use them all, an appropriate choice caninto Google translator. make it easier to understand the geology and convey our ideas to work colleaguesPseudo-relief is really quite a simple and management.attribute. I think it is essentially aRMS amplitude calculated over a Referencesmall window (half a wavelength) of aquadrature trace, but my translation may Bulhoes, E. M., 2005, Principio dabe wrong. Figure 1 displays a pseudo- SismoCamada Elemantar e sua aplicacaorelief section alongside normal seismic a Tecnica Volume de Amplitudesand a RMS amplitude section. RMS (tecVA). Ninth International Congress of the Brazilian Geophysical Society.36 PREVIEW FEBRUARY 2017

Seismic windowFigure 3. A sample of the many edge detection attributes available. Clockwise from top left: seismic amplitude, similarity, dissimilarity, semblance, faultlikelihood and maximum curvature. Attributes are calculated along the strong reflector near the top of Figure 1 (line location shown in green). This Askania magnetometer from the ASEG virtual museum is probably the oldest item in the collection. It was generously donated by John Stanley, formerly lecturer at the University of New England and inventor. Such instruments were built in the late 1920s and 1930s by Askania Werke of Berlin, Germany, and only measure only the vertical component of the field. A separate version measured the horizontal component.The resolution of 2 nT was considered to be very sensitive when first available and it superseded the use of dip needles with a 1000 times improvement in sensitivity. Operation of this variometer first required levelling the instrument on its tripod using two spirit levels. Instrument temperature was recorded from an internal mercury thermometer for the purpose of applying a compensation correction.The relative vertical magnetic force was measured off a graduated scale viewed through a microscope. Calibration scale and temperature compensation factors are not known for this instrument. Setup and measurement time at each station is estimated to be one minute for an experienced operator. FEBRUARY 2017 PREVIEW 37

WebwavesWebwaves Dave Annetts will be refined include the history section, serve interested parties better than current ASEG Webmaster the contractor’s database and Special avenues. An example of such a group [email protected] Interest Groups (SIG). The process of would be one dedicated to drones, as augmenting the contractor’s data base was suggested on the segmin (http://Consolidating changes with information such as the geophysical lyris.geosoft.com/read/?forum=segmin)to the ASEG website method(s) they employ and where they newsgroup last year, and there are likely operate has begun. to be others. SIGs can be formed with aThe start of another year, and what minor amount of effort. ASEG Membersbetter way to crash back to reality than Currently, only one SIG is listed on the interested in starting a SIG should contacta Preview column? Members may be website. The ‘Young Professionals’ SIG the Secretariat ([email protected])relieved to know that there are no major (YPSIG) is a vibrant group of young for more information.plans for the website this year. They may professionals who want to championalso be pleased to discover that two of the the interests of young employees in the Echoing themes from Preview 185major tests of the site viz. the wine offer profession of geophysics. They have a and the current issue, photos and briefand membership renewal were passed, background or interest in geophysics and descriptions of magnetometers providedlargely without drama. Some niggling are Members of the Australian Society of by John Stanley have been converted toissues remain, and these are being Exploration Geophysics (ASEG). There exhibits in the online Equipment Museumaddressed, but it is safe to say that the site is no age limit, but the group is intended (https://www.aseg.org.au/equipment-is likely to remain essentially unchanged for people aged under 35, or those new to museum). These instruments cover overfor the next 12–18 months – before the profession. Interested Members may 70 years of instrument development fromthe process of renewing the site begins contact the group at [email protected]. the 1930s.afresh. Some areas of the website that au. Figure 1 plots the user age (as determined One other SIG, the Near Surface Group, from Google Analytics) vs number of has yet to obtain the same level of site sessions between 9 December 2016 activity as the YPSIG. This is despite the and 8 January 2017. Even accounting for long history of involvement of ASEG the nature of these statistics, the large Members with near surface geophysics. number of users between 25 and 34 is ASEG Members, or non-members, who especially encouraging. However, the are interested in this group should contact age distribution of site users is clearly the group at [email protected] for biased towards older users. As the more information. science of geophysics ages along with its practitioners, so too will the tools that are A third category of SIGs is those that do employed. Some of these are superseded not yet exist. The need for such groups by modern versions, while others fall out might be established during conferences of favour as more modern instruments or Branch meetings, and an SIG may are developed. This leads to questions about what to do with the legacy data.Age 60.01% of total sessions Re-surveying with modern instruments 40% may not be possible (nor even necessary for high-quality data) for a variety of30% reasons, and while the measurement and its location can often be determined from20% a data plot, they may not be particularly usable without metadata such as filter10% settings, times, transmitter currents, etc. Some of these metadata are included0% 25-34 35-44 45-54 55-64 65+ in the reports that may accompany the 18-24 data. In cases where they do not, it may be instructive to refer to originalFigure 1. User age (as determined from Google Analytics) vs number of site sessions between 9 operator’s manuals. To this end, the WebDecember 2016 and 8 January 2017. Committee has undertaken to upload older manuals to the website (https:// www.aseg.org.au/equipment-manuals- brochures). Manuals are organised primarily by method, although the search box at the top right of the site can be used as well. Manuals, mostly as PDFs, currently on the site were kindly provided by Kim Frankcombe. Contributions from ASEG members with similar collections are always welcome.38 PREVIEW FEBRUARY 2017

Data trendsData trends Guy Holmes Everything I was seeing led me to believe to thank him, he would seem stingy – [email protected] that my DT was fit and ready for totally like me. work – but was work ready for DT? AtMy digital twin the soccer game DT had displayed So, within 5 minutes of getting into the restraint, expertise, social skills and office, DT had been faced with social,I decided to kick-off 2017 by not going self-preservation in a difficult situation, economic and technical issues that itto work anymore. I mean who needs it? all the while checking its emails, sports simply could not handle – my digital twinPlus I suspect that the team at work scores and Facebook status without was more like me than I could ever havewould not miss me – well not the actual missing a beat. It was efficient, truthful imagined.me anyway. So over the holiday period I and worked to a rigid schedule. Whatcreated a digital twin that could take my could possibly go wrong in the It is expected that in the next 3–5 years,place. workplace? digital twins will be a multi-billion dollar industry. Despite the digital twin industryInitially I was not sure that my digital So on the Monday when I/he/she/it came being built around the creation oftwin (or DT, as I like to call him/her/it) into the office, DT noticed that the coffee digital versions of physical objects (notcould go to work for me. I mean I do a machine was not working. DT being my humans) – it is very interestinglot of complex stuff and attend meetings digital twin was mechanically inept and technology nonetheless.where I am sure I am indispensable. rather than look to fix the coffeeCould my DT actually make it all work? machine, prepared itself/me to buy As an example of what a digital twin everyone a coffee from the local café might be like, imagine a roller coaster atTo test drive it, I sent DT to my son’s (instead of just turning on the coffee your favourite theme park. If the seatbeltsoccer game to see how he/her/it would machine at the wall which had been on the ride does not function correctly, thehandle the situation. I watched myself turned off over the holiday period). DT’s ride needs to be shut down until the beltsfrom a distance as DT stood on the proposed offer to buy everyone coffee are fixed. This shutdown can cost thesideline issuing lines of support to my/his was an act of generosity that would theme park thousands of dollars an hour.son and providing in depth analysis on surprise everyone, including myself andplayer positioning and goal tender in return DT. The thought of spending Imagine now that a digital version (digitalweaknesses that could be exploited. I twin) of that ride existed in softwarewatched as DT whispered under my/his/ As the Internet of Things running on a machine in the theme park,her/its breath at some of the calls the industry expands, so will and sensors on the physical ride werereferee was making. I stood in complete the growth of the digital sending real time feedback to the digitalastonishment as DT spoke to one of the twin. By using the data from the sensors,soccer moms on the sideline twin industry. the digital twin could have told thecomplimenting her on her new haircut mechanical team at the theme park thatand asking if she had been working out. I $40 on coffee where I knew only half of the belts were going to fail many hoursstarted to sweat a little while I was the people (at best) would thank me/DT or days in advance. This, in turn, wouldwatching this all unfold, so my DT for it, created a downward spiralling loop have allowed mechanics to takekicked off a fan to cool me/itself down. in the code that made DT a little dizzy. corrective actions or perform preventativeMy twin was no twin at all – it was maintenance before the fault actuallybetter than me! I knew that when someone gave me a occurred, potentially saving the park gift that the response was a ‘thank you’, thousands of dollars. but I did not programme DT with code on what to do if a thank you never came As the Internet of Things (IoT) industry in from the person receiving the gift. If expands, so will the growth of the digital DT said ‘you’re welcome’ to someone twin industry. It won’t be long before who had not even thanked him in the digital twins are deployed in oil first place, then DT would seem refineries, seismic acquisition vessels and sarcastic – which is not at all like me. If on the escalator in the international DT asked them to say thank you before terminal in Sydney that takes you to the it would give them the coffee, DT would airline club lounges. DT hates stairs – I seem like a workplace bully – a little think it is because he has no legs. more like me. If DT used his logic to only buy people coffee that were likely FEBRUARY 2017 PREVIEW 39



Book reviewGroundwater geophysics in hard rockBy Prabhat Chandra Chandra An important part of planning a reconnaissance and selection of suitable geophysical survey is setting realistic sites from a larger, more regional area.Publisher: CRC press, 2015, 384 pp. expectations of what the employed The author suggests which methodologiesRRP: £66.99 (hardback); £46.89 (eBook) technique can and cannot deliver; this might optimally address regional, localISBN: 978-0-415-66463-9 is not always possible to foresee and and detailed targets. He reviews a rangeThis book sets out to address the specific most of the time this insightfulness of techniques from satellite, airborne andproblem of using geophysical techniques comes only through experience. Most ground to borehole scale studies. Therein hard rock environments. It offers readers, as I was, would be familiar is also mention, and a brief explanation,case studies that range from the local to some extent with the majority of of methods such as seismic, groundto regional scale. The initial section is geophysical techniques presented in penetrating radar and nuclear magneticcomposed of four chapters; in the first the book, however individual levels resonance, and a discussion about howtwo the reader is introduced to different of understanding will vary according these methods can complement otheraquifer types and the hydrogeology of to personal interest or exposure to the geophysical techniques explained inhard rock environments. This section particular methods. I was particularly greater detail earlier in the book.also provides some facts on trends in interested in the two chapters onthe use of groundwater from a global the Mise-A-La-Masse and the Self The final chapter has been reservedperspective. Potential methods, both of which are not for showcasing the role of geophysicsIn chapters three and four the use of commonly employed techniques. The in managed aquifer recharge and forgeophysics, planning of surveys and book is also a good guide to the strengths monitoring groundwater contamination.what information can be expected and weaknesses of the geophysical A concluding summary on the broaderas deliverables from these surveys methods discussed. topic of groundwater geophysics inis discussed. The author suggests hard rock environments may have beeninformation such as aquifer thickness, There is enough detail in these middle more appropriate, but I believe thatbedrock delineation, location of fracture eight chapters for readers to understand consideration of these applications waszones, and lateral continuity, (amongst the essence of different geophysical placed in the final chapter to demonstrateothers) are products extractable from the techniques and what they can be used to how geophysical methods can informgeophysical data. achieve. The book also provides sufficient hydrogeological knowledge of an area,The core of the book is concentrated in references to the literature for a more enhance it, and then be transformed into athe next eight chapters (five to twelve). in-depth immersion, if that it is what is tangible product.These explain, in some detail, the sought.basic principles, field-procedures and Several of the topics covered in thisinterpretations of different geophysical For most of the geophysical methods book are clearly applicable beyond themethods such as magnetics, resistivity, reviewed case studies from the hard rock environment, particularly theself-potential, electromagnetics, and subcontinent are presented. Through these suggested approaches on integrationvariations of these techniques. case studies the author portrays different and transformation of geophysical aspects of conducting geophysical surveys measurements to hydrogeologically in hard rock environments. meaningful products. The book does a good job in reviewing some of the In the closing two chapters the author existing geophysical methods used for advocates strongly for the integration groundwater exploration and provides the of different geophysical methods, by reader with enough information to study which quantitative parameters such as when selecting a geophysical method to the thickness and extent of the saturated/ answer hydrogeological questions. unsaturated zones can be determined. He explains how these parameters can Reviewed by assist in characterisation and delineation Alan Yusen Ley-Cooper of the architecture of hard rock aquifers. Geoscience Australia The author further separates activities [email protected] and research on hard rock geophysical methods into two domains 1) where the methods are grouped as quantitative measuring tools, and 2) where the measurements and their by-products are transformed into hydrogeologically meaningful outputs. Dealing with the problem of scale is also discussed. Geophysical surveys are used for two reasons in ground water studies: (1) to determine the suitability of previously selected sites; or (2) for FEBRUARY 2017 PREVIEW 41

Development of magnetometers in Australia FeatureThe development of optically pumped magnetometer systems and theirapplications in AustraliaPart 2 John M. Stanley information in the 0.4 m to 40 m wavelength band, and this is [email protected] the band that includes anomaly sources occurring between the ground surface and 20 m depth. Instead of magnetic surveysDiversifying the application of being low-pass limited beyond 40 m wavelength, dataoptically pumped magnetometers acquisition became available covering the entire spectrum arising from surface as well as subsurface sources. The terms ‘Broad Spectrum profiles’ and ‘High Definition imaging’ were used to describe the closely sampled data acquired with the magnetometers developed at the Geophysical Research Institute (GRI). The importance of this development to magnetic exploration beneath and within the regolith in Australia cannot be overstated, as our regolith is characterised by accumulations of intensely magnetic, near surface, iron-rich minerals. Only if the magnetic response from such sources can be properly sampled can it be effectively filtered. Some classic applications of Broad Spectrum profiles to sub-surface mapping include: • Mafic sills intruding coal seams (Figure 1). • Thin dykes intruding coal-bearing sediments (Figure 2). • Deep source exploration beneath a maghemitic regolith (Figure 3).a. ‘High Definition’ and ‘Broad Spectrum’ magnetic Figure 1. This profile, recorded across a shallow thin sill, epitomises themapping significance of Broad Spectrum data acquisition. In close proximity to the surface of a mafic intrusion, magnetic minerals present contribute to a highWhen the first optically pumped magnetometer was developed it amplitude ‘white noise’ spectrum. As the sill dips to greater depth ‘upwardwas immediately recognised that if the very fast measurement continuation’ progressively low pass filters the white spectrum and in thisrate attribute could be exploited through automatic recording and profile this process can be seen to both decrease the peak-to-peak amplitudethe provision of an odometer system for automatically of the profile and to increase the wavelength between adjacent peaks. Indetermining the location of each measurement, magnetic fact, dividing the distance between adjacent peaks (DX) by the tangent of themapping would be revolutionised. With these combined Earth’s magnetic inclination provides a good estimate of the depth to the silldevelopments instead of acquiring magnetic measurements at 20 at that point. From two such measurements distance S apart, the dip angle ofm intervals or even greater, as was previously the standard, it the sill can be deduced.became practical to record magnetic profiles at sub-metre sampleintervals. This could now be done while travelling faster than anoperator could walk, and even up to 40 kph with a vehicle-borneplatform.According to sampling theory, a given sample interval can onlyenable wavelengths of twice that interval, or longer, to beproperly defined. Shorter wavelengths, if present, will beunder-sampled and will constitute ‘magnetic noise’. As a rule ofthumb, the shortest wavelength component of a magneticanomaly will be a wavelength approximately twice the depth toits source below the sensor. It follows that for any given sampleinterval only magnetic sources originating at greater than thatdistance below the sensor will be properly defined, whilesources closer to the sensor will contribute magnetic noise to theprofile.The consequence of sampling at 20 m intervals (or greater aswas more common) at ground level was that all magneticsources within 20 m (or more) of the ground surface contributedonly noise on the magnetic profile. Decreasing the sampleinterval from 20 m to 0.2 m delivered access to magnetic42 PREVIEW FEBRUARY 2017

Development of magnetometers in AustraliaFeatureFigure 2. Even very thin dykes can pose an expensive problem to longwallmining if their presence is not expected. This series of broad spectrum profilesclearly identifies near surface dykes down to 0.1 m in thickness. A pair of thinsills can also be recognised from this data.Classic examples of High Definition imaging include: Figure 3. The Elura Ag/Pb/Zn orebody consists of siliceous, pyritic and pyrrhotitic materials weathered to a depth of approximately 100 m. Overlying• Magnetic signatures of sandstone and conglomerate (Figure 4). this orebody is a maghemitic layer rich in intensely dipolar magnetic gravels.• A magnetic image of an intrusive pipe, ring dykes, uplifted Only after properly sampling the full spectrum of the magnetic noise profile from these gravels could it be effectively filtered and a quality profile stratigraphy, streambed alluvials and even buried 76 mm representing the magnetic response of the deep orebody extracted. artillery projectiles (Figure 5). The upgrade from TM-3 to TM-4 in 1989 was significant inThese examples were documented in detail by Stanley and many ways that would influence new applications. It had anCattach (1990) and Stanley et al. (1992, 2005). interface with a DGPS for both data positioning and navigation functions, and its frequency counting specifications wereb. The upgrade to TM-4 improved over the TM-3 by a factor of 20 for resolution and a factor of 40 for sample rate. Up to four Cs magnetometerIn 1988, after a period working in industry, Stephen Lee sensors could be logged simultaneously. The period counter andreturned to the GRI and developed a new concept in period data logging functions required the power of a new Motorolacounters based upon the statistical analysis of a large number of 68030 CPU with a 68881 co-processor. Data were logged on aoverlapping, short duration, windows of the Larmor period usingProgrammable Logic Array technology. The result was a countresolution of 0.005 nT at approximately 40 Hz sampling, or 0.1nT resolution at approximately 400 Hz sampling. This counterformed the basis of a new magnetometer system, the TM-4(Figure 6). FEBRUARY 2017 PREVIEW 43

Development of magnetometers in Australia FeatureFigure 4. An isometric image of high definition magnetic data in thislocation defines the distinctly different magnetic signature of a relatively ironrich conglomerate interbedded between horizons of sandstone. Four linearfeatures reveal the location of thin intrusive dykes that effectively prohibitedlongwall mining of the underlying coal seam.Figure 5. This high definition magnetic image represents 9 million, DGPS Figure 6. The TM-4 magnetometer with odometer attached. Seen also inpositioned measurements of the Total Magnetic Intensity covering a 45 ha quad-sensor application in the search for unexploded ordnance 2000 m abovearea. Data acquisition using a hand-held, quad-sensor TM-4 magnetometer the Missouri valley in Montana.took 20 crew days. Interpretable from this data are an intrusive pipe, ringdykes, uplifted sedimentary stratigraphy and alluvial drainage. Small speckles battery-backed RAM. In 2016, after 25 years of service, a TM-4revealed the presence of buried unexploded ordnance, predominantly 76 mm remains in use at Comenius University for archaeological andartillery projectiles. The four circular features in the lower section were each environmental investigations.due to a steel fence post. In 1989, differential GPS using a local base station delivered an absolute positional accuracy of around 1.5 m. In Broad Spectrum survey applications requiring precise relative sample interval accuracy a cotton thread type odometer was still used to control the sample interval along line, while the DGPS was used to position the course of the survey line and to facilitate navigation within a survey area. A vehicle-borne system using a quad-cycle44 PREVIEW FEBRUARY 2017

Development of magnetometers in AustraliaFeaturewas built for mineral exploration applications and this combined wave in the 5 Hz to 200 Hz range and hence the name Subthe relative accuracy of a digital odometer to control sample Audio Magnetics (SAM) was proposed (Cattach et al., 1993).intervals along line with the absolute position of survey transectsand navigation aids being controlled using DGPS. Hypothetically, if current were applied using grounded electrodes, four total field parameters could be extracted. These were:c. Sub audio magnetics for simultaneous electrical andmagnetic mapping • The spatially varying magnetic field intensity (TMI) • Magnetometric electrical resistivity (TFMMR) acquired duringThe significance of ‘High Definition’ magnetic mapping forresolving great detail in near surface geological structures was the ‘ON’ timerecognised from the early vehicle-borne magnetic profiles and • Magnetometric induced polarisation (TFMMIP) acquiredvarious archaeological investigations. It left a significantimpression. This immediately raised the question as to what during the ‘OFF’ timemight be the benefits for the exploration industry if similar • Electromagnetic response (TFEM) acquired during the ‘OFF’spatial resolution could be economically achieved measuringother useful parameters such as electrical conductivity, time, where in this case the EM source was the current in theelectromagnetic coupling, induced polarisation and even gravity. wire feeding the electrodesMalcolm Cattach joined the GRI team in 1980 and withsponsorship and access to the latest instruments provided by Alternatively, if the excitation source used was a closed wireNewmont Exploration, Mal commenced a Master’s program to loop, then an enhanced electromagnetic response could beevaluate, compare and perhaps suggest improvements to, the measured at the expense of the resistivity and inducedcurrent state-of-the-art induced polarisation receivers. He polarisation parameters.explored means to increase the speed with which closely spacedmeasurements might be acquired, but remained frustrated by the During the course of his PhD research into the SAM method,inherent fact that if the depth of exploration was to be Mal focused on the use of the TM-4 magnetometer with amaintained then the electrode spacing had to be large. With a galvanic source where several amperes of current werelarge receiver electrode separation measurements could only introduced through electrodes initially separated by 1000 m. Malreflect an average current flow through the large volume of diligently applied the laws of physics to calculate correctionsground between the electrodes and this would prohibit high that would be necessary if the electrical response due to changesspatial resolution. But, important seeds were sown; there had to in sub-surface conductivity properties were to be isolated. Thesebe a better way. included the subtraction of the primary field due to the current in the wire feeding the electrodes and subtraction of the normalThe benefits of high definition magnetic mapping and the desire field that would occur if the ground were homogeneous.to expand this to include other parameters of geophysicalmapping remained at the forefront of John’s and now Mal’s Malcolm achieved his goal using a galvanic source withminds. Mal proposed: ‘can we use a magnetometer to measure resounding success and the simultaneous acquisition of highthe electromagnetic response of a time-varying current in the definition TMI and TFMMR was quickly adopted by theground? If we can, then we should be able to filter between the exploration industry. Under the supervision of Malcom Cattachspatially varying magnetic field and the time varying and John Stanley, David Boggs, in his own PhD research, usedelectromagnetic field.’ It sounded too good to be true. ‘If it were TM-4 data to confirm the predicted viability of also acquiringpossible then someone would surely have already done it’. Then the transient decay signal from an electromagnetic sourceone day in 1988, John and Mal were using a TM-3 in an area (Figure 7). From this it was inferred that the transient decayalso being investigated using CSAMT and there, visible on the from an induced polarisation source would also be measurableTM-3 signal, was the CSAMT waveform. This convinced Mal to (Boggs et al., 1998).commence a PhD program under John’s supervision toinvestigate this new application (it is beside the point, but what The TM-4 and its application to SAM earned Malcolm Cattachwas actually observed was the primary field from the wires and John Stanley the 1995 ASEG Grahame Sands Award forfeeding the CSAMT electrodes, not the ground response. But Innovation in Applied Geoscience.that is the luck of the draw in research, and Mal was convincedto pursue his conviction.) d. SAM to provide discrimination between UXO and Non UXOThe concept was quite simple. If a fast-sampling magnetometerwas operated one metre above the ground surface, where the David Boggs’ feasibility assessment, confirming that highshortest wavelength of the spatially varying magnetic field is definition transient electromagnetic data could be acquiredabout two metres, at a walking speed of up to say 2 m/s (7.2 simultaneously with spatially varying TMI and TFMMR datakph), then the spatially varying field would be observed in time using the SAM technology principles, led to the recognition ofas frequencies lower than 1 Hz. If a time varying current were specific desired enhancements to the TM-4 performance. Drivenintroduced to the ground by either a galvanic source or an by these results development of the first specialised SAMelectromagnetic loop using a square wave generating source at a receiver, the TM-6, was commenced in 2002. Ron Bradburyfrequency greater than 1 Hz, then the spatially and time varying engineered an upgrade to the Steve Lee statistical period countercomponents of the magnetic field could be separated by filtering. making it now a true frequency counter with a precisely regularNaturally occurring temporal changes in the magnetic field could count rate. He was also able to raise its performance to 0.005 nTbe removed by reference to a base-station magnetometer. It was @ 120 Hz and 0.04 nT at 2400 Hz. Each measurement was ableenvisaged that the current source would deliver a bi-polar, square to be time tagged to 10 μS precision synchronised with GPS time. Up to four Cs magnetometer sensors cold be logged simultaneously. Unlike the TM-4, which had its own display screen and keyboard, the interface with theTM-6 was via a Bluetooth connection with an off-the-shelf, hand-held device. FEBRUARY 2017 PREVIEW 45

Development of magnetometers in Australia Feature This enabled the TM-6 to be more conveniently carried in a backpack, leaving the operators hands free (Figure 8). With DGPS now capable of delivering cm positional accuracy, the requirement for an odometer system was overcome in even the most demanding sampling applications. The processing power and storage capacity were also increased permitting the use of real-time navigation aids, real-time signal stacking where required and digital recording at very high data rates.Figure 7. Images of TMI, TFMMR and TFEM acquired simultaneously Figure 8. The TM-6 magnetometer system with ports for up to four Cswith a TM-7 magnetometer using SAM. sensors and a frequency counter capable of delivering measurements to 0.04 nT resolution 2400 times per second with each measurement time tagged46 PREVIEW FEBRUARY 2017 to 10 µS precision synchronised to GPS time. Data positioning with cm accuracy and survey navigation aids was provided by DGPS. On-board signal stacking delivered a noise floor of just 0.05 pT for electromagnetic exploration applications.

Development of magnetometers in AustraliaFeatureAt the time of the TM-6 development the major cost in had to be designed and built capable of driving up to 350 Ampremediating contaminated military sites was recognised as current through a square loop of dimension 110 m surroundingarising from the labour intensive investigation of false alarm a 1 ha search area. Keith Matthews brought his experience withsources. Magnetic field mapping was effective in detecting high power, fast shutoff transmitter technologies to the teamferrous items to a depth in most environments beyond the and the result was the MPTX-500 transmitter (Figure 9).expected penetration depth. But highly remnant magnetised Calculation of the transient electromagnetic response from a 20fragmentation could not be distinguished reliably from mm projectile in the energising field produced from such a loopdangerous UXO items. Electromagnetic metal detectors were revealed that the TM-6 magnetometer frequency counter nowrelatively cumbersome to use but were more discriminating had the performance to detect the transient response from aagainst fragmentation as they responded in a manner more source as small as the 20 mm projectile target. The predictedproportional to the target dimensions. Electromagnetic detectors performance of SAM in this application was confirmedalso had an advantage in being capable of detecting non-ferrous during an evaluation program sponsored by the USitems. However, electromagnetic systems deploying a small, Environmental Security Technology Certificationroving coil transmitter were inherently limited in their detection Program (ESTCP, 2003).depth. The energising signal decreased nominally with theinverse cube of the depth to target and the induced signal also e. Identifying induced polarisation using SAMdiminished with an approximate inverse cube relationship withdistance back to the receiver. Consequently, detection depth The simultaneous measurement of Total Field Magnetometricusing a small coil energising source decreases with nominally Induced Polarisation together with TFMMR and TMI wasan inverse 6th power. A magnetometer achieves a greater always specified in the hypothetical concept of SAM. But it wasdetection depth primarily because the source is passive and its not until the TM-6 technology had evolved that an inducedresponse decreases only with a nominal inverse cube polarisation signal could be confidently distinguished fromrelationship. SAM technology was seen as a viable solution for electromagnetic coupling. Recent case studies by Gapboth reducing the false alarm rate and for increasing the Geophysics have confirmed David Boggs’ prediction that allelectromagnetic detection depth. Not only could the magnetic four parameters could in practice be simultaneously measuredand the electromagnetic response be acquired simultaneously with a single, Cs magnetometer sensor.with a single sensor, but the energising field could be appliedusing a very large loop surrounding, for example, a whole ha. f. SAMSON for deep penetration electromagneticFrom such a source the energising field remains constant surveysbeyond the depth of concern and so the electromagneticresponse follows just the inverse cube law instead of the inverse The successful application of the TM-6 magnetometer and6th power experienced with a roving coil transmitter. Using MPTX-500 transmitter to electromagnetic detection of UXOSAM the detection depth of both magnetic and electromagnetic targets was the precursor to the next stage of SAM developmentresponses would be equivalent, both measurements would be for mineral exploration applications. In 2005 Malcolm Cattachprecisely co-located and in combination would deliver enhanced brought together a development team under the new organisationdiscrimination capability. of Gap Geophysics. During the years 2006 to 2008, the TM-6 magnetometer/SAM receiver underwent ongoing development,The TM-6 specification was defined such that it would enable a evolving into the TM-7, with significant enhancements tolarge loop SAM system to detect UXO targets as small as a 20 acquisition electronics and firmware as well as processingmm projectile (approximately 20 mm diameter, 100 mm software (Figure 10).length). In order to meet this specification a current transmitter Total Field Electromagnetic measurement became practical as anFigure 9. The MPTX-500 transmitter was developed as an EM source offspring of the SAM concept. In 2007, SAMSON (‘Son ofcapable of delivering up to 350 Amp current through an energising square SAM’) was developed as a collaboration between Gaploop of 110 m x 110 m. When such a loop surrounded a 1 ha search area Geophysics and ElectroMagnetic Imaging Technology (EMIT).SAM technology, using a TM-6 magnetometer, was capable of detecting UXO The distinguishing feature of SAMSON was the use oftargets down to 20 mm projectile size. stationary measurements and real-time signal stacking in order to enhance the signal-to-noise ratio of weak transient responses from very deep sources. In the application of SAMSON to very deep exploration it is practical to achieve late time noise levels of 0.05 pT with a typical measurement station occupation time of 5 minutes. But while the measurement time might now be relatively long, the requirements of deep source exploration can be met with measurement stations 50 m apart. This is a distinctly different application of the Cs magnetometer sensor to those previously focused upon the high definition mapping of near surface sources. Such is the diversity in applications of the Cs sensor. SAMSON earned for Andrew Duncan, Malcolm Cattach and Steven Griffin the 2007 ASEG Laric Hawkins Award for the most innovative use of a geophysical technique from a paper presented at the ASEG Conference (Duncan et al., 2007). FEBRUARY 2017 PREVIEW 47

Figure 10. The TM-7 magnetometer system is the current Development of magnetometers in Australiageneration. Its performance is similar to that of the TM-6 butadvantage has been taken of advanced acquisition electronic Featurecomponents, firmware and processing software. g. High-power transmitters to support SAM technologies When using the TM-7 magnetometer SAMSON methodology was able to achieve a measurement sensitivity that was well within ambient noise when transmitters available at the time were used. It soon became clear that further improvements to sensitivity would not improve the signal-to-noise ratio. However, if higher powered transmitters could be made available then improvement in signal-to-noise using the TM-7 could be expected. Gap GeoPak (GeoPak) was established in 2007 as a joint venture between Australian companies Gap Geophysics Pty Ltd and Kayar Pty Ltd (engineering company).The objective in establishing the company was to develop a range of high performance geophysical transmitters that would: • Significantly exceed the performance and reliability of commercially available transmitters • Optimise the signal-to-noise ratios achievable by Gap Geophysics proprietary and non-proprietary survey techniques. • Significantly increase the depth of exploration for electrical techniques. • Reduce station occupation time thereby increasing survey efficiency. • Incorporate enhanced safety features which meet and exceed the more stringent requirements of today’s mining exploration industry. Gap GeoPak’s flagship products are the HPTX-70/80 range of high power transmitters. With the ability to achieve up to 350A and power output up to 80kW, these transmitters have pioneered high power, deep penetrating EM surveying in Australia (Figure 11). The GeoPak HPTX-70 earned Malcolm Cattach, Keith Mathews, Ed Campbell and Symon Bouwman the 2012 ASEG Grahame Sands Award for Innovation in Applied Geoscience.Figure 11. The HPTX-80 transmitter is capable of delivering 80 kW of electrical power to either a galvanic source, where electrodes may be separated by severalkm, or to an electromagnetic loop of several square km area. With such a transmitter, and the TM-7 magnetometer, very deep electromagnetic exploration can beachieved using SAMSON technology or the survey efficiency of a helicopter-borne platform can be applied to TMI and TFMMR exploration using SAM technology.48 PREVIEW FEBRUARY 2017