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Schlumberger Public 4/23/2004MWD and LWD IntroductionGraham RaeperLWD Interpretation & DevelopmentSchlumberger DCS Scandinavia Schlumberger Public

Schlumberger Public 4/23/2004© Schlumberger 2004 Schlumberger PublicAn asterisk is used throughout this presentation to denote a markof Schlumberger. Other company, product, and service names maybe trademarks, registered trademarks, or service marks of others.2 GR4/23/2004

Schlumberger Public 4/23/2004 Measurement While Drilling Tools Schlumberger Public – Measure the Direction & Inclination of the wellbore – Allow drilling tools to be oriented (mud motors, Whipstocks) – Provide mechanism for transmitting downhole data to surface – May provide Gamma Ray & Drilling Mechanics measurements – May provide power for LWD tools Logging While Drilling Tools – Measure petrophysical properties3 GR4/23/2004

4/23/2004 MWD History Schlumberger Public • Early Patents Schlumberger Public •Jakosky patent, 1929 • Otis & Alder, 1955 4 GR 4/23/2004First WL log (resistivity) 1927SP 1931Induction Resistivity & dipmeter 1947Density – 1957SNP (neutron) & compensated density - 1962First DD in 30’s (1934 for first relief well)

Schlumberger Public 4/23/2004MWD Evolution Schlumberger Public – 1960’s – Teledrift tool developed - mechanical inclinometer with positive mud pulse, still used today – 1969 – SNEA & Raymond Precision Industries start development work on mud pulse telemetry MWD system (these projects are combined to form Teleco in 1972) – 1978 – Teleco MWD tool commercialized – 1980 – Schlumberger complete first MWD job in the Gulf of Mexico -Multi-Sensor MWD tool (D&I/ GR/ RES/ DWOB/ DTOR) – 1984 – NL Baroid Introduce first 2MHz resistivity tool – 1986 – First Triple Combo (GR/ RES/ Density Neutron) LWD string – 1993 – Sonic compressional LWD tools introduced – 2001 – Seismic while drilling, Formation Pressure while drilling5 GR4/23/2004

4/23/2004Telemetry Principles Mud Pressure Time Positive Pulse: Schlumberger Public 1 BPS Mud Continuous wave: Pressure up to 12 Bits Per Second Time Negative Pulse: Schlumberger Public Mud 2 BPS6 GR Pressure4/23/2004 TimeStarting with our telemetry, on this slide is represented the PowerPulseseries of MWD tools.All those tools specifications are listed in the drilling services catalogs thatyou were provided. Please refer to this documentation for specifications.All PowerPulse tools are identical except for the 6” holes where thestandard PowerPulse is replaced by the Vision475 MWD, a combination ofPowerPulse and Vision Resistivity.The PowerPulse comprises 5 elements, a collar, which only has one plugson the outside (the read out port), extenders to allow communication withLWD tools, a turbine to power the tools, an electronic cartridge to controlturbines and modulator as well as communication with LWD tools, andfinally a unique telemetry system, the modulator.The way the modulator is working is simple as you can see on the rightside of the slide, it is composed of a stator and a rotor, when the rotorturns it is closing and opening the gap on the stator thus creating apressure wave.This pressure wave is captured on surface. The interesting thing is that weare actually not looking at the delta pressure seen on surface but rather atthe frequency of this pressure wave.This gives us the fastest and the most reliable telemetry on the markettoday.

4/23/2004MWD Inside... Schlumberger Public The MWD Sonde is centered in the collar Schlumberger Public (Mud flow in the center of the tool for some LWD tools)7 GR4/23/2004

4/23/2004 Schlumberger Public Schlumberger Public 8 GR 4/23/2004

Schlumberger Public 4/23/2004 MWD Systems available in different sizes Schlumberger Public PowerPulse* Impulse* SlimPulse* 9 GR 4/23/2004Objective: MWD tools available today

4/23/2004MWD Surveys Sensors Extender Extender 3 Accelerometers + 3 Magnetometers Schlumberger Public10 GR Schlumberger Public4/23/2004

4/23/2004MWD Surveys SensorsSensor sets arranged orthogonally Schlumberger Public Inclination Error: Azimuth Error: Schlumberger Public - Movement - Magnetic parts - Misalignment of the MWD - LWD Power - Collar Mass collar in the wellbore - Collar Hot Spots - Accelerometer misalignment - Temperature11 GR4/23/2004

4/23/2004 Uncertainties Well path is computed from surveys by minimum curvature method -1200 -1000 -800 -600 -400 -200 0 200 400 600 800 400 400 A-2 AH Survey SPIDER VIEW 1600 A-1 H Survey Scale (1 cm = 100 m) 200 A-3 H PlanNORTH >>> 200 Schlumberger Public 1500 1400 1300 1200 2100 2000 1600 1900 1500 1400 1300 1200 0 2177 1600 Inclination accuracy: 0.1° 0 -200 1700 (FMI GPIT Incl. Acc. = 0.5°) 2000 1800 Default Color 2100 Main 1700 Proposal 1800 Survey 1900 A-2 H Pilot Survey Azimuthal Accuracy: 1° -200 (FMI GPIT Az. Acc. = 2°) -400 2325 -600 2300 -400 2100 2200 1300 2000<<< SOUTH 19000 2100 1400 1800 2000 1500 1600 1700 -600 A4H Plan 12 GR -1200 -1000 -800 -600 -400 -200 0 200 400 600 800 Schlumberger Public 4/23/2004 <<< WEST EAST >>>

4/23/2004Link from MWD tool to LWD tools Extender Extender Schlumberger PublicA BHA must be assembled from tools around 30 ft long„ A link must be provided for electrical connection to other tools in the string – SLB use extenders to provide the link to between MWD and other tools – An alternative method is to use an electrode set into the thread face of the collar – Extenders provide both the communication and power link13 GR Schlumberger Public4/23/2004

Schlumberger Public 4/23/2004Logging While Drilling Schlumberger PublicThe goal in developing LWD tools was to provide nearwireline quality measurements while drilling„ Early MWD tools provided basic electrode (short normal) type resistivity & Gamma Ray measurements„ 2 MHz resistivity tools developed to obtain higher quality resistivity measurement in all mud types„ Density/ Neutron measurement developed to provide Triple Combo service – supports large percentage of wells14 GR4/23/2004

4/23/2004Triple Combo Schlumberger Public Gamma Ray, Resistivity, Density, Pef, Neutron Schlumberger Public• Provides measurements of most commonly used wireline string• Majority of LWD logs are not duplicated by equivalent wireline service15 GR4/23/2004

4/23/2004LWD FE Capability - Today…Measurements Conveyance WL Conveyance LWD Schlumberger PublicThermal Neutron Ø yes yes Schlumberger PublicBulk Density yes yesAzimuthal Density no 16-binsPhotoelectric factor yes yesSpectroscopy / Sigma yes noMulti-depth Propagation R 5 outputs 20 outputsMulti-depth Laterolog R 5 outputs 5 outputsAzimuthal Resistivity 12-bins 56-binsMicro-Resistivity Image yes noCompressional Dt yes yesShear Dt yes yesSeismic Check shot yes yesVSP Yes yes (memory only)Formation Pressure yes yesFluid samples yes noNMR yes yes16 GR4/23/2004 Objective: High Service Quality

Schlumberger Public 4/23/2004 LWD Acquisition Workflow - Differences Schlumberger Public between Wireline and LWDWireline „ Data is directly associated to depth indexes as it is acquired- DLIS „ Depth is calculated from length of cable in hole - independantLWD „ Tools do not know the depth / only surface systems know the bit depth „ Tools record data in time (clock, resets, shifts) „ 2 types of acquisition: Real-Time and Recorded Mode „ Real time data, transmitted by the MWD tool via pressure pulses in the mud column is associated with depth as it is acquired 17 GR 4/23/2004

Schlumberger Public 4/23/2004 Surface Sensors Schlumberger Public Depth sensor SPT Weight/Torque Pump press. Pump stroke Surf. RPM Etc…18 GR4/23/2004

4/23/2004 Schlumberger Public Schlumberger Public The MWD unit 19 GR 4/23/2004

4/23/2004 Signal Demodulation Schlumberger Public Principles Schlumberger PublicType of signals „ Downhole (MWD-Motor..) „ Uphole (Pumps-Rig..) „ Echoes & Reflections „ Electrical NoiseCharacteristics „ Frequencies „ Attenuation „ Direction20 GR4/23/2004

4/23/2004 Schlumberger Public Schlumberger Public DSPScope 21 GR 4/23/2004

4/23/2004DSPScope Spectrogram Schlumberger Public22 GR Schlumberger Public4/23/2004

4/23/2004Demodulation Schlumberger Public 23 GR Schlumberger Public 4/23/2004Objective: Understand DemodulationThe Frame Display function is the parent application of SPM Demodulation. Thisapplication performs the following functions:• Translates the raw bits demodulated by the receiver module into raw data pointvalues (D-points).• Sends the D-points to the IDEAL backend.• Displays the decoded frame and decoding status.The Frame Display application also contains a toolbar to launch or open theassociated window of many of the SPM Demodulation functions. Simply clickingon one of the toolbar buttons displays the appropriate control window.The Frame Display window displays any number of previous frames and is onlylimited by screen size. Simply resizing the window with the mouse covers oruncovers as much frame history as desired. The values are displayed in rawdecimal format. The conversion to engineering units occurs after being sent toIDEAL.The Frame Display window displays the most important demodulationinformation on the screen. You can check the• Decoded raw D-points• Sync status (In Sync, Out Of Sync Pump Down, Signal Loss, Searching, orPrecursor)• History decoded frame quality• Frame ID

4/23/2004Telemetry is KeyDrilling Optimisation Data… 70 50 65 Increased rate of penetration 40 60 55 30 Stick Slip 20 CD&I50 45 40PWD INCL (deg) AZI (deg) Schlumberger Public (/m) 35 10 30 25 0 1500 2000 2500 3000 3500 4000 4500 5000 MD(ft)Formation Evaluation Data…1 bit per second 3 bits per second 6 bits per second QC Data High Res Or 2.2 BPS log and a Or 4.3 BPS log and a Real-time density image Real-time resistivity image Advanced LWD (m/hr) Schlumberger Public24 GR4/23/2004 0.8 BPS 1.7 BPS

4/23/2004Recording Mode Acquisition Rate Schlumberger PublicTo record 2 samples/ft Schlumberger Publicwith an acquisitionrate programmed at 10sec, your ROP have tobe limited to180ft/hr(60m/hr) 25 GR 4/23/2004

4/23/2004Read-Out Port (ROP) ROP Communication with tool Schlumberger Public to downlaod memory Battery switch (LWD) Schlumberger Public26 GR4/23/2004

Schlumberger Public 4/23/2004Data vs Time -> Data vs Depth Schlumberger Public Depth vs Time + Data vs Time = Data vs Depth27 GR4/23/2004

4/23/2004Time to Depth Conversion Depth Based Data Time Based Data Schlumberger Public HOUR 0.00 Gamma Ray 150.00 Schlumberger Public28 GR 0.00 Gamma Ray 150.004/23/2004

Schlumberger Public 4/23/2004Errors from Time/Depth merge Schlumberger Public To present recorded LWD logs, the data (recorded downhole against time) needs to be combined with a surface measurement of depth (also recorded against time). This can lead to additional errors due to the incorrect alignment of the two independently recorded times: „ The clocks might be incorrectly synchronized. „ Clocks are not perfect, and will drift. „ Clocks can “reset”, causing jumps. Each of these effects cause unpredictable effects on the log. However, the time/depth merge can easily be checked by comparing the RM data with the RT data. 29 GR 4/23/2004

4/23/2004 Schlumberger Public Schlumberger Public Depth Tracking 30 GR 4/23/2004

4/23/2004Depth Acquisition Schlumberger Public Any changes in depth entered Schlumberger Public by the engineer is reported Depth encoders31 GR4/23/2004 Depth Log / Tracking Sheet

4/23/2004Depth - What does the Client Want? Schlumberger PublicTrue Depth Schlumberger PublicAbsolute DepthRelative DepthReproducible Depth 32 GR 4/23/2004

4/23/2004Which Depth is That? What is the depth of this formation top? Wireline depth, Schlumberger Public attempt 2 Driller’s depth True depthAnadrill’s depth at time t233 GR Anadrill’s depth Schlumberger Public4/23/2004 at time t1 Wireline depth, attempt 1

Schlumberger Public 4/23/2004 LWD Depth vs Wireline Depth Schlumberger Public Wireline depth is the Geoscientist’s reference. Driller’s depth is the Driller’s reference. If Wireline depth is corrected properly, it is more accurate; but those corrections are difficult to apply, and are often incomplete. The corrections are greater than the inaccuracy of driller’s depth. The industry does not want two different measurements of the same thing. They want a repeatable measurement. Depth is our most important measurement.34 GR4/23/2004

Schlumberger Public 4/23/2004 Depth Measurement Schlumberger PublicLWD’s depth is the driller's depth.There are 3 different areas that affect the accuracy of LWD depth (closeness totrue value): 1. Difference between driller’s depth and true depth. 2. Difference between LWD’s measurement of depth and driller’s depth 3. Errors caused by the incorrect alignment in time of the depth file and the data file (time/depth merge problems)35 GR4/23/2004

Schlumberger Public 4/23/2004 Difference Between Driller’s Depth and Schlumberger Public True Depth Driller’s depth comes from measuring the length of pipe in the derrick. Effects it does not account for include: „ Drillpipe stretch „ Thermal Expansion „ Ballooning effects „ Errors in the measurement IIttisisaavvaalildidmmeeaassuurreemmeenntt,,uusseeffuullffoorr ddeetteerrmmininininggbbeeddtthhicickknneesssseessaanndd ggeeoosstteeeerrininggaapppplilcicaattioionnss 36 GR 4/23/2004•Additional errors are introduced whenmeasuring the depth of deviated holesas the pipe does not lie in the center ofthe hole.•Errors are also introduced in theconversion from measured to truevertical depth.

4/23/2004Summary of stretch calculationsHorizontal Well. Schlumberger PublicA well was analyzed using drilling engineering software. The well was vertical to 3000ft. Then, it built at 3 deg/100 ft to 38 degrees, which was held until 13000 ft. It built againat 3 deg/100 ft to 90 degrees This was achieved at 14679 ft. Total depth was 17960 ft.The following results were obtained from the analysis for the amount of pipe stretch: Sliding into the hole 3.75 ft Reaming into the hole at 200 ft/hr 8.67 ft Rotating off bottom 8.75 ft Reaming out of the hole 9.08 ft Sliding out of the hole 13.52 ft37 GR Schlumberger Public4/23/2004

Schlumberger Public 4/23/2004Difference between LWD’s measurement of Schlumberger Publicdepth and driller’s depth Draworks sensor, Geolograph and/or Rig Motion Sensor (RMS) used to determine block position Clamp Line Tensiometer (CLT) used to determine when drillpipe goes into and out of slips. Combination of above used to determine length of pipe in the hole. Checked against driller’s pipe tally every connection. 38 GR 4/23/2004

4/23/2004MWD Depth Measurement Schlumberger Public39 GR Schlumberger Public4/23/2004

4/23/2004 Schlumberger Public Schlumberger Public LWD Measurements

4/23/2004Resistivity Frequency Range Schlumberger Public41 GR Schlumberger Public4/23/2004

Schlumberger Public 4/23/2004Why 2MHz? Schlumberger PublicInduction-type LF measurement relies on cancellation of the direct coupling (balanced arrays) „ very sensitive to geometry, not suited to LWD (shock)At 2MHz, phase-shift and attenuation can be measured between two coilsBorehole compensation cancels differences between the two receivers42 GR4/23/2004

Schlumberger Public 4/23/2004 2 MHz Resistivity TheorySchlumberger Public Current from Top Transmitter induces an electromagnetic field within the formation. This propagates away from the transmitter. The wave induces a current at the receivers. The phase and amplitude of the wave are measured and converted to resistivity.43 GR

4/23/2004Propagation Measurement Transmitter EM-wave is attenuated in Schlumberger Public conductive formations Receiver Receiver Near receiver Far receiver Transmitter Finite propagation speed44 GR causes phase-differences4/23/2004 Schlumberger Public

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4/23/2004Emag Wave Geometry Schlumberger Public Equal phase lines Equal amplitude lines Schlumberger Public47 GR4/23/2004

4/23/2004ARC475/Phasor induction DOI Schlumberger Public48 GR Schlumberger Public4/23/2004

4/23/2004ARC475/Phasor induction Schlumberger Public49 GR Schlumberger Public4/23/2004

4/23/2004DOI Considerations Schlumberger Public 2 Parameter Influencing DOI: Schlumberger Public Distance from Transmitter to Receiver • The greater the distance T/R the deeper the DOI Signal frequency • The lower the frequency the deeper the DOI50 GR4/23/2004