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Schlumberger Public 4/23/2004400 KHz Measurement Schlumberger PublicDepth of investigation: „ Deeper in conductive formations „ Similar in resistive formationsAdvantages: „ Better signal in conductive formations (< 1 Ohm.m) „ Less sensitive to eccenteringLimitation: „ Less accurate at higher resistivity (low PS & ATT sensitivity to Rt)51 GR4/23/2004

4/23/2004Depth Of Investigation Comparison Schlumberger Public52 GR Schlumberger Public4/23/2004

4/23/2004Blended (Best) Resistivity 2MgHz Phase Shift Schlumberger Public 400KHz Phase Shift 2MgHz Attenuation 400KHz AttenuationEccentering Effect 53 GR Schlumberger Public 4/23/2004Sorry about the quality--This log shows a log that has been severely affected by eccentering. 2-MHz tools are severely affected byeccentering when there is a large Rt/Rm contrast or a large Rm/Rt contrast. In this case the blue curves intrack two are the 2-MHz phase shift outputs and the black curves in track three are the attenuation curves.Both are affected by eccentering that has been exaggerated by a washout. In this case the environmenthad a large Rm/Rt contrast (OBM and a Rt of less than 1 ohmm.One of the biggest advantages of the 400-kHz outputs is the immunity to eccentering. To take advantageof the deeper reading 400-kHz at low resistivity and the immunity to eccentering as well as take advantageof the higher signal to noise ratio and better vertical resolution of the 2-MHz a new output was created. Itis called the blended or best resistivity (P16B--Phase shift 16 -in spacing /blended output). The 400kHzcurve is presented below 1 ohmm, the 2MHz output is presented above 2 ohmm and the output is aweighted average between 1 & 2 ohmm. This will be the standard presentation for the commercial versionof IDEAL 6.1 The blended outputs are the red and green curves. Note that they are very well behaved.

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4/23/2004 Polarization Horn Effect Schlumberger Public55 GR Schlumberger Public4/23/2004

4/23/2004 Polarization Horn Effect Schlumberger Public56 GR Schlumberger Public4/23/2004

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Schlumberger Public 4/23/2004 VISION Schlumberger Public Resistivity vs. AIT 58 GR 4/23/2004The VISION resistivity log is extensively used for formation evaluation. It has a similarresponse to the Array Induction Tool. Here five PS curves are plotted against the AIT. At lowresistivities, PS curves have about a one foot vertical resolution. The resolution is notconstant like the AIT, as the PS resolution degrades to 2 feet at 50 ohmms.The attenuation curve resolution is severely affected by an increase in resistivity. Theattenuation curve has a resolution of 2 feet at 1 ohmm but 8 feet at 50 ohmms.The curve mnemonics are also different from that of an AIT.For a VISION curve:•1st letter denotes the curve--either P for Phase Shift or A for attenuation•second two numbers represent the spacing (10,16,22,28,34, or 40 -inch)• Unlike the AIT this is not the constant depth of Investigation!!!•The last letter is either “H” for High frequency (2-MHz) or “L” for low frequency (400-kHz)Note that the IMPulse currently does not have the 400-kHz option but will be modified latter in2000 that will provide it with increased memory to 50 MB, dual frequency, digital electronicsand simultaneous acquisition.

4/23/2004GeoVISION Resistivity Tool Schlumberger Public59 GR Schlumberger Public4/23/2004

4/23/2004GeoVISION Resistivity GVR Azimuthal Button Resistivity Measurements Schlumberger Public Schlumberger Public

4/23/2004GeoVISION Current Focusing Schlumberger Public61 GR Schlumberger Public4/23/2004

4/23/2004Ring Resistivity Principle Schlumberger Public62 GR Schlumberger Public4/23/2004

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4/23/2004WL dual laterolog Resistivity response Schlumberger Public64 GR Schlumberger Public4/23/2004

4/23/2004GVR focused Ring Resistivity response Schlumberger Public65 GR Schlumberger Public4/23/2004

4/23/2004GRV Imaging: Break-outs and Schlumberger PublicButton Averaging Schlumberger Public66 GR4/23/2004

4/23/2004GVR Azimuthal Caliper Schlumberger Public 67 GR Schlumberger Public 4/23/2004Caliper data can be acquired from several sources using LWD data.• A real-time ultrasonic caliper is made with the Vision675 density tool• resistivity caliper from the CDR, ARC and RAB in WBMToday the resistivity calipers are only available in memory but should be available in real-timeby the end of the year (99).The caliper data provides a picture of the shape of the bore hole, indicating the severity offormation breakout and the primary directions of failureThe diagram above shows caliper data from the Geovision resistivity tool at different depths,highlighting that breakout has occurred long the north-west / south-east plane.The resistivity image data from the same tool over the same interval clearly shows the areas ofbreakout along that planeThe caliper data can also be used to potential hazardous areas while tripping, running tubularsor wireline

4/23/2004GVR and FMI Comparison Azimuthal Resistivity for Geological and Fracture Analysis Schlumberger Public 68 GR Schlumberger Public 4/23/2004• Fracture presence and orientation are often key parameters todrilling successful horizontal wells.• This examples compares a wireline FMI Formation Micro-Imager (left image) to a GeoVISION resistivity image (rightimage) acquired during the drilling process.• Note the fracture in the middle of each image. This sine wavehas a different orientation to the bedding planes.

4/23/2004 GeoVISION Real Time Images Real Time Image Recorded Mode Image 70 ft Schlumberger Public69 GR Schlumberger Public4/23/2004 Ref.: SPE - 71331This is an example of a compressed and decompressed image comparedto a recorded mode image straight from the tool memory (I.e. retrievedwhen the tool was on the surface. Although the resolution of thecompressed and decompressed image is poorer the main feature ofcutting up through a thin conductive bed can clearly be seen.

4/23/2004Density Neutron Measurement Schlumberger Public Wireline density tools Schlumberger Public typically use a skid mounted source & detector to obtain good contact with borehole LWD tools use different methods to record density data with the lowest standoff as the tool rotates Neutron porosity measurements can be corrected for mud standoff70 GR4/23/2004

4/23/2004Vision Azimuthal Density Neutron (VADN) Schlumberger Public -AmBe neutron source -He3 detecNtoerustron -Thermal nSeeuctrtoionns -C137 Gamma ray source -Two gain-Dsteanbsiliitzyed Nal scintillationSdeectteiocntors71 GR Schlumberger Public4/23/2004

4/23/2004 Density Borehole Compensation RHOmc < RHOb DRHO > 0 RHO ls Schlumberger Public RHOmc > RHOb DRHO < 0 RHO ss RHOb = RHO ls + DRHO DRHO = f (RHO ls - RHO ss) “SPINE & RIBS” algorithm Schlumberger Public RHOb compensates up to 1” stand-off72 GR RHOmc4/23/2004

4/23/2004 Schlumberger Public Schlumberger Public 73 GR 4/23/2004

4/23/2004ADN Dual Source Assembly Assembly Schlumberger Public Density Source Neutron Source74 GR Schlumberger Public

4/23/2004 Schlumberger Public Schlumberger Public 75 GR 4/23/2004

4/23/2004 CLAMP-ON STABILISER Schlumberger Public BUILT-IN STABILISER76 GR Schlumberger Public4/23/2004

4/23/2004ADN Images Theory AAzziimmuutthhaall ssoouurrccee aanndd ddeetteeccttoorrss AADDNN DDeennssiittyy IImmaaggee Schlumberger Public CCoolloorr ssccaallee QQuuaaddrraanntt aarrrraayyss Schlumberger Public77 GR4/23/2004

4/23/2004Image Resolution (Relative pixel sizes) Schlumberger PublicOne inch Pef GVR UBI FMI scale Density Schlumberger Public78 GR4/23/2004Despite this coarseness of image, density images can prove invaluable.They can be acquired in oil and water based muds. Using LWD allowsmeasurements in complex shaped wells that would require risky TLC runsif they are possible at all.Furthermore many of these wells are logged at high angles, where eventhin bed are seen over many feet within the borehole.As with any imaging tool a contrast in the medium being measured isrequired to identify beds.

4/23/2004Image resolution Limitation6 in Schlumberger Public 8.5 in Schlumberger Public 35° ™The sinusoids are not resolved for apparent dips of less than 35 Degrees

4/23/2004 VADN Images PowerDrive - 2D ImagesUltrasonic Schlumberger PublicPefRHOS Schlumberger PublicRHOB (quad.) ROSIRHOB (sect.) ROIMRHOL 80 GR 4/23/2004

4/23/2004Comparison Real Time vs. Memory Image RTI RMI Schlumberger Public81 GR Schlumberger Public4/23/2004

LWD Calipers 4/23/2004Ultrasonic Caliper direct DerivedDensity CaliperPhase Caliper from Propagation Tool Schlumberger PublicCaliper from multiple DOI ResistivityNeutron Caliper82 GR Schlumberger Public4/23/2004

4/23/2004Ultrasonic Caliper Measurement Schlumberger Public Borehole spiraling Schlumberger Public83 GR4/23/2004

4/23/2004 Advantages of the Ultrasonic Caliper Schlumberger Public • Direct and Azimuthal Measurement Schlumberger Public • Works in OBM and WBM • Good Precision (0.1 –0.2 in.) • Available in Real Time Factors that Affects Accuracy Acoustic Impedance Contrast between Mud and Formation Signal Attenuation in Heavy Mud Standoff Range up to 2.5 in. Hole Rugosity / Target Alignment84 GR4/23/2004

VADN/FMS Schlumberger Public4/23/2004Image Comparison Drilling Schlumberger Public down 85 GR sequence 4/23/2004 parallel to bedding Drilling down sequence

4/23/2004 Schlumberger PublicVADN VADN Schlumberger PublicDensity PefDynamic Dynamic Image Image

4/23/2004Azimuthal Density Reveals Filtrate Drape Schlumberger Public Azimuthal Formation Evaluation - Gravity Segregation of Fluids Gas filtrate 87 GR Schlumberger Public 4/23/2004• This is a quadrant density presentation from a horizontal well in a highpermeability gas zone.• All quadrant densities (top, bottom, left and right) are “crossed-over” the neutron inthe characteristic gas signature.• The quadrant densities themselves do not agree in the homogeneous formation.The bottom density has the highest reading. The top density is the lightest.• This is due to filtrate drape - gravity segregation to the bottom of the wellbore.This generally occurs in high permeability gas zones due to the buoyancy force.•Note the difference that this may make on resistivity measurements - GVR wouldbe useful in this case to compute quadrant water saturations.

4/23/2004Azimuthal Porosity GeoSteering Schlumberger Public 88 GR Schlumberger Public 4/23/2004This example illustrates the benefit of azimuthal density geosteering. A gas zone is overlain by a shale. Inzone A, all four quadrants measure low densities and crossover the neutron, indicating a gas zone. Thetop quadrant has a lower density than the bottom quadrant. This may be a result of “filtrate drape”, whichis gravity segregation of filtrate invasion toward the low side of this horizontal well.The drillpipe is sliding for a short section, until zone B. The density measurement for the top of thewellbore has increased as it is now measuring the shale bed above the wellbore. The other threequadrants (bottom, left and right) still indicate gas. With the azimuthal measurement, you would now makea decision to turn down, away from the shale boundary. However, with an average density, it may noteven be recognized that the wellbore was approaching a shale boundary.The tool and drill pipe slides again to zone C. Now the wellbore is further into the shale section. Only thebottom density indicates gas. Only now, would an average density reading indicate that a steeringdecision would need to be made, but it still would not provide a direction.

Schlumberger Public 4/23/2004 Sonic while drilling Schlumberger Public transmitter Receivers Receivers Attenuator Transmitter 89 GR 4/23/2004Bottom Hole Assembly - ISONICThe ISONIC8 is combinable with any 8-in. LWD measuring device and istraditionally run with LWD triple combo tools (e.g. CDR/RAB and CDN).Similarly, the ISONIC6 can be run with all 6 3/4-in. collar LWD/MWD tools.Both tools can be run with all bit types. Pictured is a typical quad-combo bottomhole assembly. In such a configuration, the ADN/CDN will always be at the topof the BHA to allow for source retrieval. The ISONIC would be typically next,but it can be placed anywhere in the string, above or below the MWD tool, evenjust above the bit in “low noise” environments (e.g. rotary drilling - not hardrocks).The ISONIC can be run with or without a downhole motor or geosteeringassembly.

4/23/2004ISONIC-Array Sonic While Drilling Schlumberger Public90 GR Schlumberger Public4/23/2004

4/23/2004Recorded Mode Data Schlumberger Public91 GR Schlumberger Public4/23/2004

4/23/2004ISONIC Vs. Wireline Sonic Schlumberger Public92 GR Schlumberger Public4/23/2004

4/23/2004Delta-T in Overpressure Zone Schlumberger Public93 GR Schlumberger Public4/23/2004

4/23/2004ISONIC Applications Real-time Schlumberger Public Porosity measurement Schlumberger Public Lithology identification Seismic correlation real-time input for synthetic seismograms Pore pressure trends while drilling Real-time decision making Recorded mode Porosity measurement Lithology identification Mechanical properties (hard rocks) Improved quality sonic measurements „ Formation alteration (shales) & invasion „ Hole enlargement94 GR4/23/2004ISONIC ApplicationsISONIC applications can be divided into two groups - real time and recorded modeapplications . Real time measurements provide the client with unique opportunities forbetter drilling decisions. The two main applications are real time seismic correlation andpore pressure indication.Real Time Seismic CorrelationFrom real time ISONIC compressional slowness measurements, real time syntheticseismograms can be computed. These seismograms can be used to correlate the client’ssurface seismic data to driller’s depth. The client will learn where the bit is located on hisseismic section. This gives the client the opportunity to re-evaluate his drilling operationbefore he reaches total depth.Pore Pressure IndicationIn most sand/shale sequences, compaction increases with depth due to increasingoverburden with depth. Sound travels faster through sand/shale sequences the morecompacting occurs. Therefore, compressional delta-t lessens with depth at relativelyconstant rate. When overpressured formations occur, pore space is greater than normaland the delta-t value increases above the expected trend. Therefore, slow delta-t valuesabove the compacting trend indicate overpressured formations.Recorded ModeThe major recorded mode application is wireline sonic replacement. Seismic tie andsonic porosity (computed from delta-t and used as an input to the petrophysicalevaluation (i.e. lithology, porosity, etc.) are the primary customer objectives for sonic data.When running ISONIC in fast rocks, shear slowness can be acquired from the recordeddata. Combining shear with compressional slowness allows for mechanical propertycomputations such as IMPact*, MechPro* and Frachite*.ISONIC compressional data is gathered well before wireline data can be acquired. Thismeans that the measurements are made before formation alteration, stress relief,invasion and increasing hole enlargement can occur. The result is that ISONIC slownessmeasurements may be a truer representation of the formation properties than subsequentwireline sonic measurements.

4/23/2004LWD Shear Measurement Schlumberger Publicin Slow Formations The presence of drill collar requires an alternative to standard wireline-like technology. A Dipole measurement requires a very large dispersion correction R&D programs led to the starting of development work in quadrupole technology for LWD95 GR Schlumberger Public4/23/2004

4/23/2004Why Quadrupole? Borehole with collar Empty boreholeDipole Borehole mode Strong collar Schlumberger Public Formation Shear interference More sensitive Less sensitive Collar mode to shear to shear Small collar Borehole mode interference Formation Shear Collar modeQuadrupole96 GR Schlumberger Public4/23/2004Shear slowness in slow formations is derived from the measurement ofdipole or quadrupole modes. Both of these modes are dispersive. Theypropagate at the shear slowness at low frequencies. As the frequency getshigher sensitivity to the shear slowness decrease and sensitivity to mudslowness and other environmental parameters increase. Therefore, onewould like to make the measurement at as low frequency as possible.However, for the dipole mode the presence of the drilling collar in theborehole interferes with the formation dipole wave at the low frequenciesmaking it very difficult to extract formation shear information if at allpossible. The quadrupole collar mode on the other hand is cut-off at lowfrequencies and interferes very little with the formation quadrupole wave.In summary quadrupole measurement is much better suited to shearlogging in slow formations in LWD environment.

4/23/2004Seismic While Drilling Principle Surface System MWD telemetry Source Surface source Schlumberger Public sea floor Downhole receivers Waveforms recorded in LWD Tool downhole memory97 GR Downhole processing4/23/2004 Real-time check-shot via MWD telemetry Look-ahead imaging seismic reflector Schlumberger Public

4/23/2004SeismicVision System Surface System Downhole Tool Schlumberger Public Rugged LWD technology Triangular cluster (450 in3) Multiple sensors (3 Geophones, 1 Bottled air supply Special control system Hydrophone) Processor, memory, telemetry Schlumberger Public 98 GR 4/23/2004SPE71365The SeismicMWD system has two main components, a downhole tool anda surface system.The downhole tool was constructed of typical rugged LWD technology. Itwas configured with multiple sensors including geophones, hydrophonesand accelerometers. In addition, it has a processor for downholecomputations, memory for storing data and a telemetry system fortransmitting data to the surface.The surface system for these tests included a triangular airgun cluster witha total volume of 450 cu in. A bottled air supply was used to reducemaintenance for the long “while-drilling” operation. A specially developedcontrol system was used to activate the source in a manner that would besynchronized with the downhole recordings.

Schlumberger Public 4/23/2004 Check shot data from Seismic While Drilling Schlumberger Public Wireline 99 GR 4/23/2004First field test in Wyoming.Traces in top section acquired while tripping down.Bottom trace acquired while drilling at connection time.Wireline VSP was run after the test. Very good match inche-ckshot times.

4/23/2004 Applications Schlumberger Public Real-time check-shot Schlumberger Public „ Put the bit on seismic map „ Update seismic velocities for PPP „ Optimize ECD boundaries and drilling parameters „ Update velocities for seismic reprocessing Real-time salt proximity Seismic look-ahead, 500+ ft (2003) Replace intermediate wireline check-shot, save rigtime100 GR4/23/2004