Borehole Seismic Introduction. Seismic Signals in the borehole Borehole Environment Borehole survey types Borehole seismic deployment Overview

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  • Slide 1
  • Borehole Seismic Introduction
  • Slide 2
  • Seismic Signals in the borehole Borehole Environment Borehole survey types Borehole seismic deployment Overview
  • Slide 3
  • A VSP or Vertical Seismic Profile is the process of recording seismic data in a wellbore environment. The geophones are vertical in the earth versus horizontal along it as in surface seismic. What is a VSP?
  • Slide 4
  • Checkshot Vertical Incidence Walkaway 3D-VSP DBSeis Offset VSP Salt Proximity Zero Offset LWD Tool SeismicMWD Integrated Seismic Surveys GECO LONGVA OSLO Pressure & Temperature Flow & Phase 4C Sensors Borehole Seismic Surveys
  • Slide 5
  • Introduction Seismic Signals in the borehole Borehole Environment Borehole survey types Borehole seismic deployment
  • Slide 6
  • Depth Time Downgoing direct arrival Downgoing multiple Reflected upgoing primary Reflected upgoing multiple Seismic Signal in the Borehole
  • Slide 7
  • Depth Time Time-Depth Seismic Reflections Vertical Seismic Profile
  • Slide 8
  • Depth Time Surface Seismic VSP Transit Time (TT) TT Reflection Time (OWT) OWT TT TWT = OWT + TT Reflection TWT One-Way Time vs. Two Way Time
  • Slide 9
  • Borehole Multiples Upgoing Multiples
  • Slide 10
  • Borehole Multiples Downgoing Multiple
  • Slide 11
  • Borehole Multiples All Multiples
  • Slide 12
  • Tube waves are generated when surface waves from the source come in contact with the borehole fluid and become a guided wave traveling up and down the borehole. As the tube wave travels vertically in the borehole it pushes the wall horizontally. When the geophones are properly clamped to the borehole wall most of the tube wave energy will be seen in the horizontal geophones. At changes in the borehole dimensions some of the tube wave energy will be reflected back to the surface. This will also occur when the energy reaches the bottom of the hole. Tube Wave Energy Source
  • Slide 13
  • Tube Waves Raw Data One-Way Time Depth Horizontal Channel Vertical Channel Tube wave Y X HODOGM Y X
  • Slide 14
  • Surface Seismic Comparison Depth Offset Two-Way Time One-Way Time VSP Data Surface Seismic
  • Slide 15
  • Introduction Seismic Signals in the borehole Borehole Environment Borehole survey types Borehole seismic deployment
  • Slide 16
  • Resonance types & effects Resonance generates signal distortion Coupling resonance effect Modal resonance effect
  • Slide 17
  • Resonance Attenuation Reduce tool dimension & mass Increase tool application force Optimize contact geometry Combined tools Shaker Coupling contacts Geophones Isolating springs Versatile Seismic Imager - VSI Isolated geophone package: 3.5 lbs Positive mechanical anchoring Combinable Seismic Imager - CSI Isolated geophone package: 20 lbs Positive mechanical anchoring Array Seismic Imager - ASI Isolated geophone package: 9 lbs Magnetic clamping
  • Slide 18
  • Shaker Response
  • Slide 19
  • Introduction Seismic Signals in the borehole Borehole Environment Borehole survey types Borehole seismic deployment
  • Slide 20
  • Borehole Seismic History CheckshotSingle Trace2-D Lateral Coverage
  • Slide 21
  • Checkshot Surveys Formation Travel Times Formation Travel Times Formation Velocities Formation Velocities Depth-Velocity Model Inputs Depth-Velocity Model Inputs Surface Seismic Correlation Surface Seismic Correlation Wavelet Processing Wavelet Processing Acoustic Impedance Synthetic Seismogram Surface Seismic Depth (m) Time (s) Source Geophones Depth Model CHECKSHOT
  • Slide 22
  • Zero Offset VSP Surface Seismic Correlation Surface Seismic Correlation Over-pressure Zone Prediction Multiple Pattern Identification Multiple Pattern Identification Wavelet Processing Wavelet Processing Formation Velocities Formation Velocities Corridor Stack Surface Seismic Depth (m) Time (s) Source Geophones Depth Model ZERO OFFSET
  • Slide 23
  • VSP Image Surface Seismic Depth (m) Time (s) Depth Model Sources Geophones Vertical Incident VSP Surface Seismic Correlation Surface Seismic Correlation Lateral Coverage Beneath Well Multiple Pattern Identification Multiple Pattern Identification Fault and Dip Identification Fault and Dip Identification Formation Velocities Formation Velocities WALKABOVE
  • Slide 24
  • Offset VSP Surface Seismic Correlation Surface Seismic Correlation Fault and Dip Identification Fault and Dip Identification Salt Proximity Identification Salt Proximity Identification Shear Wave Analysis Shear Wave Analysis Surface Seismic Survey Design Surface Seismic Survey Design VSP Image Surface Seismic Depth (m) Time (s) Source Geophones Depth Model OFFSET
  • Slide 25
  • Imaging Walkaway Surface Seismic Correlation Surface Seismic Correlation Fault and Dip Identification Fault and Dip Identification Shear Wave Analysis Shear Wave Analysis Surface Seismic Survey Design Surface Seismic Survey Design Depth (m) Source Geophones Depth Model VSP Image Surface Seismic WALKAWAY
  • Slide 26
  • AVO Walkaway True Seismic Amplitude With Changing Offset True Seismic Amplitude With Changing Offset P-P and P-SV Analysis Reflector Source Positions P-Wave S-Wave AVO WALKAWAY Anisotropy velocity model Q factor analysis
  • Slide 27
  • Salt Proximity Survey Provides Accurate Salt Face Image 2D, 2.5D and 3D Imaging Solutions
  • Slide 28
  • 3D VSP Very High Sub- Surface Imaging Resolution Exploration and Development Applications Detailed Preplanning and 3D Modeling Required 3-D VSP Well 1Well 2 Well 1Well 2 3D-VSP Depth Migration Surface seismic 3D PSDM 3D VSP
  • Slide 29
  • Introduction Seismic Signals in the borehole Borehole Environment Borehole survey types Borehole seismic deployment
  • Slide 30
  • Borehole seismic on Wireline Applications All seismic applications Operations - Max deviation dependant of well liquid type & well geometry (example: so far, ASI ran in 77 deg deviation, in Brine) Downhole Geophones Source Reference Sensors Recording Unit Downgoing Wavefront Pit
  • Slide 31
  • Pipe Conveyed Acquisition Applications All seismic applications Operations Max deviation: no limit (113 o exp) Ex : 3 * CSI / MDT / Pex / DSI Extendable CSI sub isolates geophones from tool body & pipes Wet connect CSI Pressure sampling Sonic Neutron Gamma density Tension sub Resistivity Gamma spectroscopy Compression sub
  • Slide 32
  • Through Drill Seismic TDS Applications All seismic applications, & particularly... Position of the drill bit: on the surface seismic from the target... Imaging beside the well... Prediction ahead of the bit Operations Data acquisition... Tool Pumped down Reciprocate between levels No circulation Acquisition 10 min max Min deviation so far = 7 deg Max deviation so far = 90 deg Saving rig time Taking effective and fast decisions Conventional VSP source GAC sensor Drill bit TDS Thru-Drill Seis
  • Slide 33
  • Logging While Drilling Applications Real Time checkshots... Position of the drill bit: on the surface seismic from the target Along with ISONIC: Calibration of ISONIC data & RT Synthetic seismogram Operations Saving rig time Taking effective and fast decisions seismic reflector LWD Tool sea floor MWD telemetry SeismicMWD seismic reflector Drill Bit Sensors Weights Sensor sea floor Source Drill Bit Seismics Surface System
  • Slide 34
  • Through Tubing Seismic Applications All seismic applications, & particularly...... Imaging beside the well (coil tubing drilling, well redevelopment, etc) Operations Data acquisition - Stop production VSP source Geophones (GAC)
  • Slide 35
  • Simultaneous Acquisition Applications All seismic applications, & particularly... Acquiring borehole seismic data before surface processing starts: Velocity anisotropy, Q attenuation, AVO, VSP-guided processing, shear model Operation Tool stays stationary in the well Platform Joint acquisitions with GP

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