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Oil and Gas Imaging, pumpsandpipesmdhc
 

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Oil and Gas Imaging, pumpsandpipesmdhc Oil and Gas Imaging, pumpsandpipesmdhc Presentation Transcript

  • Oil and Gas Imaging Bruce VerWest, PhD Research Manager – External & Strategic R&D CGGVeritas Pumps & Pipes 1 November 12, 2007
  • Goal of Seismic Imaging
    • Seismic Imaging – a primary tool for oil & gas exploration
      • Determine reservoir geometry, shape, position
      • Determine reservoir properties – lithology, pore fill (brine, oil or gas)
    • Approach and challanges
  • Seismic Acquisition – Listening for Echos Marine Acquisition Plan view
  • Seismic Acquisition – Listening for Echos
    • The Tool
      • Acoustic echos (5-80 Hz.)
      • Image reflected energy
      • Subsurface velocity unknown
      • Velocity complex -> ray path distortion
    • Limitations of data acquisition
      • Data acquired on one side of target – the earth’s surface
      • Reservoir details are on order of meters – seismic wavelengths are tens to hundreds of meters
      • We are interested in subsurface properties but we measure property contrasts
  • Seismic Imaging Forward problem Inverse problem Non-unique Incomplete Unstable Acquisition Seismic data Model building Imaging
  • Seismic Imaging is a Two Step Process
    • Determine velocity ->
      • Acquire data with varying source receiver separation
      • Use stereo tomography to determine velocity
      • Traveltimes yield low resolution view of subsurface velocity
    • Image data ->
      • Back propagate measured sound wavefield to form image
      • Various approximations to the acoustic wave equation are utilized
    • Iterative process since the velocity is part of the image
  • Multiple source receiver separation data
    • Multiplicity of data helps in noise removal
    • Traveltimes from data at varying offsets yields information about medium velocity
    Receiver station Time (sec) Receiver station Source
  • An Example - Subsurface Model
  • An Example – Complex Wave Propagation
  • An Example – Seismic Data x t
  • An Example – Imaging Velocity x z
  • An Example – Imaged Output x z
  • Kirchhoff Beam 1-way Wave Equation Jack Discovery – Different 3D Imaging Algorithms
  • Changing the acquisition geometry to improve imaging Narrow Azimuth Acquisition Wide Azimuth Acquisition N S N S Jack #1 Jack #1 x X X
  • Repeat Over 1000’s of sq. km. Detailed depth top salt interpretation covering 19,000 sq km
  • CGGVeritas Town Park Computer Center Computer Totals Cpu’s >15060 Memory >32 TBytes Disk > 3676 TBytes
  • Supercomputer Peak Performance 1980 1990 2000 2010 Year Introduced 1 Pflop Peak Speed (flops) 1 Tflop 1 Gflop 1 Mflop CRAY-1 CRAY-2 X-MP4 Y-MP8 SX-4 SX-5 T3D T3E Doubling time = 1.5 yr. Blue Gene (367 Tflops) CGGVeritas Houston
  • Recent Advances to Improve Imaging
    • More accurate (and expensive) imaging algorithms
    • Better tools for velocity model determination
    • Increased acquisition aperture
  • Current Problems in Seismic Imaging
    • Poor illumination – shadows, absorption
    • Complex velocity model determination (including anisotropy)
    • Imaging steep dips and complex structure
    • Resolution –> loss of high frequencies and higher velocity at depth
    • Multiple reflections
    • Other Noise
  • Oil and Gas Imaging Pumps & Pipes 1 November 12, 2007