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4/23/2004Example Exploration Well Plan 20” Normally pressured Schlumberger Public 16” clastics 13 3/8” Pressure ramp 11 3/4” 9 5/8” Reservoir Schlumberger Public101 GR4/23/2004Now let’s imagine drilling an exploration well in a highly challengingenvironment with the SeismicMWD tool.The exploration basin is characterized by normally pressured clastics inthe shallow section, then a section with a severe pressure ramp and highlyover-pressured reservoirs.To reach a deeper reservoir, the well must be geosteered accuratelythrough a step out section with an uncertain velocity profile.To meet all of the objectives, wells in this region normally require flawlessplanning, many casing strings and careful execution.The well plan calls for a 20-, 13 3/8- and 9 5/8-in casing sequence andcontingent liners of 16 and 11 3/4-in. If needed, the contingent liners wouldrequire underreaming and add considerable extra cost.The key to success is to push the 20-in casing as deep as possible and toset the 13 3/8-in casing exactly at the top of the pressure ramp that is anobvious reflector on the surface seismic map but not easily recognizableas a lithology change.

Drilling Office - Bit on Seismic Schlumberger Public4/23/2004Time-Depth SurfaceCurve and SeismicDepth in DepthPrediction Schlumberger PublicDistanceto Target 102 GR 4/23/2004

4/23/2004 Schlumberger Public Schlumberger Public Bit On Seismic 103 GR 4/23/2004

4/23/2004LWD-NMR Schlumberger Public 104 GR Schlumberger Public 4/23/2004This is a picture of the tool taken while testing at RMOTC (Rocky Mountain Oilfield Test Center) in June 1999this is actually a picture of the first generation tool, but the second generation is essentially identical in theantenna region shown here. The only difference is in the new tool has a longer section of slick drill collar thanthe original tool. The tools currently being deployed are second generation tools.Describe pictureThe spiral piece at the bottom is the field replaceable screw on stabilizer that is changed in the same way as adrilling motor stabilizer.Above this are antenna and wear bands.The rest of the tool is slick.Outline Presentation.Questions rules (encourage interruption?)

4/23/2004NMR While Drilling Schlumberger Public„ Tools available to Schlumberger Public measure T2 (or T1) in real time„ Measurement complicated compared to wireline by tool motion105 GR4/23/2004

4/23/2004 LWD-NMR Outputs Schlumberger Public Real Time Outputs Schlumberger Public – Lithology Independent Porosity – Bound Fluid Volume (BFV) / Free Fluid Volume (FFV) – T2LM (Log mean of T2) – Permeability – Hydrocarbon from Multi-Wait Time Porosities Additional Outputs from Recorded Mode – Raw Echoes – Full Data Re-Processing – Full T2 Spectra – Motion Data106 GR4/23/2004LWD-NMR OutputsThe tool performs downhole a T2 inversion and computes outputs for transmission in realtime. These real-time outputs could be used for GeoSteering, well placement, sidetrackdecisions, etc….Direct hydrocarbon identification using porosities from multiple polarization times (examplesshown later) (see FAQ’s for description of hydrocarbon identification/characterizationmethods)Permeability is calculated uphole from the bound fluid free-fluid ratio using Coates-Timurequation or from the SDR equation if T2LM is transmitted, coefficients and exponents forthese equations can be set by the user at the wellsite based on client desires.The tool records the raw echoes and this data can be used to reprocess the data in theIDEAL wellsite software. A more detailed (more components in T2 spectrum) can becomputed from the raw data. In addition, the tool records full accelerometer andmagnetometer data whose primary purpose is for QC of NMR data, but some interestingdrilling engineering applications will also be shown.-------------------------------Note that the downhole memory of the tool is obviously not unlimited. No “maximum footageloggable” specification can be given as the tool records verses time. Currently the tool canrecord around 104 megabytes of memory. Note that the tool only records while circulating.Prior to the job during the planning stage the memory can be set up to record for longerperiods of time by stackking the raw echoes. As NMR data is inherently statistical and whenreprocessed the echoes are stacked anyway, there is no significant loss of information. Inthis way, the memory can be programmed to last as long as required.

4/23/2004Measurement & MotionResonant region Schlumberger Public Borehole Wall Experiment Region Resonant Region 107 GR Schlumberger Public 4/23/2004The slide above shows the tool at first centered in the borehole at the beginning ofthe measurement cycle. An experiment region is established with the 90degreepulse, the 180 pulse should then be performed with a coincident resonant zone, i.e.the tool should not move. The diagram on the right shows how the resonant regionstays at a fixed radius around the tool but the experiment zone is fixed in theformation. In other words the experiment is now in error due to movement.This is clearly a very great challenge with the drilling environment, either theexperiment has to be fast compared to the motion and or the tool should bestabilized to reduce motion.Also the slide demonstrates where the measurement is made. In a cylinder of aparticular thickness around the tool. It is where the magnetic field and the frequencyof the radio signal combine to produce a resonant effect in the hydrogen nuclei, thisis how only hydrogen is measured in the experiment. And also that no signal isreceived from in front of or behind the resonant zone. In other words there is a welldefined and constant measurement region from this tool unlike other nuclear orresistivity tools.

4/23/2004Drilling Dynamics From Accelerometry 0.1 cmBit Whirling Schlumberger Public&Hole 1.0 cmEnlargement 108 GR Schlumberger Public 4/23/2004The above are examples of the kinds of whirling motion it is possible to resolve using thetools capabilities.Each graph shows the locus of lateral movement of the center of the tool, as it moves in thebore hole. The scale is in meters, top left shows millimeter size whirl, top right sub millimeterand bottom left shows centimeter range movement of about an inch that was constrained bythe tool hitting the borehole wall.These motions are more or less damaging according to their shape and frequency ofoscillation. The lower left hand one may be particularly damaging as the oscillations aremuch larger amplitude (6-7 cm) and the BHA is whirling around the outside of the boreholecontributing to borehole enlargement and possibly damaging formation by compressing mudcake into the formation.-------------------------------------------------------------------------These were all recorded in one bit run in a shallow vertical hole with a rock bit at 500 ft/hr and80-150 rpm parameters.

4/23/2004Quality Control of Motion Effects Lateral motion leads to Schlumberger Public shortening of T2’s Effects Understood Accelerometers Æ lateral motion velocity QC from Accelerometry data. QC from NMR data109 GR Accelerometry Data Æ Maximum Measurable T2 Schlumberger Public4/23/2004Accelerometer Package is for QC PurposesThe motion data can be used for quality control of the log in recorded mode or real-time byutilizing the lateral velocity of the tool, to compute the maximum T2 that can be resolved.This is an example drilling through a gas sand. From the accelerometry package we cancalculate an average lateral velocity shown in track 1. This leads to the red line in the T2 trackthat shows the limit of the T2 that could be resolved under the motion conditions experiencedby the tool while the measurements are made. You can see that the transition from shale tothe shaley gas sand sees the appearance of a second T2 peak that is to the left of the T2maximum line. A separation from the line of about a decade indicates that there is probablylittle or no motion shortening of the T2. Further down in the slightly better pay the T2 peakincreases in time to the right but is still to the left of the line so is certainly not noise, butbecause it is a little closer to the line it will be somewhat shortened due to tool motion.NMR standalone QC is also being investigated by looking only at the NMR data anddetermining motion effects by looking at the NMR data itself.

4/23/2004Formation Pressure While Drilling Draw Down Pump Schlumberger Public Pressure Gauge„ Measurement principle identical to Sealing Element wireline formation pressure System Volume measurements Schlumberger Public„ Rely on direct contact with the formation„ Drill string movement must be stopped„ A small area of the formation is sealed off, and the pressure & mobility is tested„ Dual packer type tools also exist Tool shown is not a Schlumberger tool110 GR4/23/2004

4/23/2004GeoSteering -The full picture…UDR Distance to boundary Vision Res. Medium DOI Schlumberger Public TT R Base Balder GVR or VDN Real-Time Image Gas injectors shall be drilled near top reservoir Top Heimdal Producers shall be drilled 9 m above Base Heimdal Schlumberger Public OWC or near base reservoir Top Chalk111 GR4/23/2004

4/23/2004Drilling Performance Sensors Schlumberger Public 112 GR Schlumberger Public 4/23/2004VISION has a variety of Drilling performance sensorsDownhole weight, torque and multi-axis vibrations are not available onVISION475.PERFORM is a service which provides a Specialist Engineer who uses thedrilling performance sensors, surface indicators, offset well data,knowledge database and local knowledge to improve the drilling processto identify and reduce risk as well as improve overall ROP.

4/23/2004Increase Drillstring and Bit Life BHA whirling in vertical holeMulti axis shocks • Reduce drillstring fatigue • Reduce borehole enlargement • Increases ROP/bit lifeLarger shocks result in more shock counts Schlumberger Public 113 GR Schlumberger Public 4/23/2004All of Anadrill’s MWD and LWD tools are designed with downhole shockmeasurements.In the MWD tools shock data is transmitted in real-time such that in theevent of high shocks drilling parameters can be adjusted and the effectsmonitored.Real-time shocks can reduce non productive time, as trips can be savedby:• reducing pipe fatigue• failure of downhole components• increasing bit life.Multi axis shock measurements are also available (ie. Axial, lateral andtorsional) With this information it is possible to determine the type ofvibrations experienced (e.g. bit bounce, stick slip, resonance etc.) andthus take appropriate actionThe shock measurements are alsoused to track wear and tear on the toolsand the level of maintenance required on a tool is based upon the severityof shocks experienced.It should be noted that although the MWD/LWD electronics are the mostsusceptible damage from shocks, failure of these components is notcatastrophic. Where as the effect of high shocks on BHA connections canlead to catastrophic failures.

4/23/2004Early Washout DetectionBHA whirling in vertical hole Output Voltage vs. Flow Rate for 8-in. Turbine Schlumberger Public 114 GR Schlumberger Public 4/23/2004The PowerPulse/Impulse MWD system uses a downhole turbine togenerate power. The output voltage from this turbine is directlyproportional to the flow rate passing through the tool and is thus a valuabledownhole flow meter which is sensitive to very small changes in flow.As the example shows, any washout above the MWD tool is easily seenfrom the turbine voltage, a lot earlier than it is seen at surface. Earlyidentification can help reduce non productive time for expensive fishingtrips. This can be set up as a smart alarm on the IDEAL system, thusrequiring no continuous interpretation of the data by the engineer.

4/23/2004Stuck Pipe Avoidance Schlumberger PublicWeight on Bit Torque 115 GR Schlumberger Public 4/23/2004The PowerPulse tool can be configured to provide real-timemeasurements of downhole weight on bit and torque. Thesemeasurements are made based on strain gauges mounted in the MWDtool.The gauges for the weight on bit are aligned so that they are only sensitiveto the axial load (tension and compression on the drillstring). The torquegauges are aligned so that they are only sensitive to the torsional effectson the drillstring (I..e. not the axial forces)These measurements are particularly valuable in deviated wells wheresurface parameters of weight and torque can be unrepresentative of thetrue downhole conditions. By using the downhole measurements theperformance of the bit can be optimized and premature damage of PDCbits avoided.By comparing both surface and downhole parameters a calculation of thefriction in the wellbore can be made and the onset of pipe.stickingdetected and action takenThe example shows how the sliding friction (drag) is increasing, indicatingthe onset of a potential sticking problem. A wiper trip was made and thelog shows the impact of the corrective action. In this case it wassuccessful and drilling was resumed.Thus using these measurements NPT an be reduced by optimizing bitperformance and avoiding stuck pipe.The calculated friction factors are also a valuable input into the planning ofthe next well.

4/23/2004Accurate control of ECDModeled vs. Actual ECD Schlumberger Public • Key for Deepwater drilling Schlumberger Public • Detect shallow water flows • Detect cuttings loading and swab/surge effects • Manage the pore pressure fracture grad window 116 GR 4/•23M/200i4nimize mud weight for optimum ROPAnadrill can provide real-time annular pressure measurements in eachhole size. This measurement is used to calculate the true ECD (effectivecirculating density) while drilling to ensure that the ECD remains higherthan the formation pore pressure, yet lower than the fracture gradient ofthe formation.Right hand diagram: shows the theoretical ECD (black). Withoutdownhole measurements this is the value used to define the mud weightrequired to drill the well. The red curve shows the actual ECD asmeasured by the downhole sensor and shows that there are majorfluctuations, compared to the modeled value, as a result of changing flowrate and RPM. Other key factors that can effect the ECD are cuttingsloading pipe eccentricity, swab surge effects and temp/pressure effects. Itis clear therefore that in a well where there is a tight window between theformation pore pressure and the fracture gradient to rely on a modeledECD value is dangerous and that real-time monitoring is crucial. This isparticularly true in the case of deepwater drilling where there can be a verynarrow window.The ECD can also be calculated there is no circulation for accurate leakoff/formation integrity test measurements and to monitor swab/surgeeffectsThe APWD measurement has also proven to be a valuable tool for theearly detection of shallow water flows (a sharp increase is seen)All annular pressure measurement can also be stored in the toolsdownhole memory.

4/23/2004Staying within the Pressure WindowStaying within the pressure window ISONIC example Schlumberger Public 117 GR Schlumberger Public 4/23/2004Left hand diagram: shows a real-time plot of the real-time ECDmeasurement plotted against the theoretical fracture gradient and a real-time calculation of pore pressure based on LWD resistivity. The porepressure calculation is compared to the seismic pore pressure calculationthat was made prior to drilling the well.Accurate monitoring of both the pore pressure and ECD are key. This isparticularly the case in deepwater wells were the window between fracturegradient and pore pressure can be very narrow.Right hand diagram:shows an example of how LWD sonic data can alsobe used for real-time pore pressure evaluation. The normal compactiontrend of the formation would result in a gradual decrease in sonic transittime. However, in overpressured formations we see that the formationbecomes less compacted and the sonic transit time diverges from itsnormal trend and increases as a function of over pressure.

4/23/2004 Identification of Failure ModesShear FailureMud Weight tooLow Schlumberger PublicTensile Failure Stress DirectionMud Weight tooHigh 118 GR Schlumberger Public 4/23/2004LWD images can be acquired from both the GVR(GeoVISION Resistivity) and ADN (vision density).As well as clearly showing the interbedding of theformations and the dip of the beds, these images canbe used to define fractures. Both the direction of thefractures and the failure mode can be determined.When combined with Real time images, this will be veryvaluable in refining or confirming wellbore stabilitymodels and drilling practices.But in the above example, the explanation shows thatthe mud weight is too high AND too low. How can thisbe--which is it?

Schlumberger Public 4/23/2004Conclusion Schlumberger PublicMWD/ LWD has developed quickly compared to wirelinetechnologyThe technique is widely used in deviated wells and where rig ratesare highIn vertical wells and low rig day rates wireline is more economical – is there a need for RT data?Almost all OH wireline measurements can be performed with LWD – fluid sampling and high definition images are the significant measurements not yet available DEPTH control is the biggest single quality factor that affects LWD measurements119 GR4/23/2004