Seismic Acquisition and Processing

Course Duration: 40 contact hours, including lecture-based modules, hands-on exercises, and workshop on Nigeria examples (including in-house examples if available)

Who Should Attend:

Geophysicists, Geologists, Exploration/Production Managers, and Reservoir Engineers.

Course Summary: The seismic dataset represents an essential tool for extracting information about the subsurface, including both exploratory and developmental stages, ranging from general structural/stratigraphic interpretation to reservoir characterization. Proper acquisition design should consider specific goals of the survey, cost, and ultimately enhancing signal response while suppressing noise, while simultaneously considering current processing/reprocessing techniques. This course details the seismic acquisition and processing stages, from treatment of the fundamentals of seismic wave propagation, land/water design strategies, source and receiver types, bandwidth enhancement, noise reduction, processing sequence (details on deconvolution, migration, and stacking), and so forth. Aspects of 2D versus 3D versus 4D (time-lapse) seismic surveys, as well as microseismic and passive seismic monitoring will be addressed. Because of the inherent need to integrate well log data, borehole seismology will be discussed, including acoustic logging tools and imagers, vertical (and reverse vertical) seismic profiles, and crosswell seismology. Numerous hands-on exercises will be used to supplement primary lecture modules and case studies for an enhanced learning experience.

You will Learn How to:

• Understand better the fundamentals of seismic wave propagation,
• Understand better aspects of seismic acquisition, and
• Understand better aspects of seismic processing.

Tentative Topics and Outline

• Review of the Seismic Process
  • Seismic waveforms, including body (compressional/dilational) and surface (Love, Rayleigh, and other forms)
  • Elastic properties (velocity, density, and elastic moduli)
  • Wave propagation and energy loss mechanisms
  • Reflection seismology
  • Refraction seismology (in context of near surface characterization and wellbore acoustic measurements)
  • Resolution and bandwidth
  • Mode conversion
• General Acquisition Considerations
  • Cost, sustainability, and planning
  • Geological considerations
    • Depth to target horizon, maximum dip, and lateral and vertical resolution
• Seismic Source Types
  • Desired qualities of the source (from the theoretical Dirac pulse to reality)
  • Land-based systems (dynamite, vibroseis, and other source types)
  • Water-based systems (airgun, water bubble, etc.)
  • Wellbore (monopole, dipole, and quadrupole excitation; ultrasonic transducer)
  • Bandwidth and frequency (traditional, sparker, well log, etc.)
  • Direct S-wave generation versus mode-converted waves
  • Fracture stimulation as a source signal for microseismic monitoring
  • The reservoir itself as a source for passive seismic monitoring
• Receiver Types and Systems
  • Desired qualities of the receiver
  • Hydrophone and/or geophone
  • Multicomponent recording
    • P- and S-wave recording
    • Pressure and displacement
  • Electromechanical and/or optical recording
  • Geophone string versus node systems
    • String (swath), including fixed (land or water bottom), towed streamer (water and now land), dual streamer operations
    • Node systems (land and water)
  • Sampling in time and space
    • Digital recording and temporal aliasing
    • Spatial aliasing and F-K analysis
• Signal Enhancement and Noise Reduction
  • Noise types and attenuation
    • Coherent versus incoherent
    • Removal of surface waves (ground roll attenuation)
    • Removal of ghosts/multiples
  • Stacking techniques
    • Gather types for quality control, noise suppression, etc.
• Design Parameters
  • General parameters
    • Fold
    • Offset
    • Bin size
    • Shot line spacing
    • Receiver line spacing
    • Swath versus patch
  • Azimuthal requirements
    • Benefits of multiazimuth data
    • Narrow azimuth versus wide azimuth versus full azimuth
    • Shear wave splitting and birefringence
• Additional Acquisition Technology
  • Time-lapse seismology
    • Repeatability
    • Permanent installations
  • Wellbore seismology
    • Acoustic/sonic logs, including monopole, (crossed) dipole, and LWD quadrupole
    • Imaging technology (ultrasonic transducer, cement evaluation, crossed-dipole anisotropy)
    • Vertical seismic profiling, reverse vertical seismic profiling, and crosswell profiling
    • Bit noise seismic and seismic proximity surveys
  • Microseismic monitoring
    • Surface and wellbore monitoring of microseismic events from fracture stimulation
  • Passive seismic monitoring
    • Reservoir monitoring
    • Passive seismic as an exploration tool (the 3 Hz hydrocarbon signal)
• General processing considerations
  • Introduction to general processing sequence of deconvolution, migration, and stacking
  • Initial processing and subsequent reprocessing
• Preprocessing
  • Demultiplexing
  • File conversion
  • Trace edit 

• Amplitude Adjustment
  • Gain control
  • Zero phasing
• Deconvolution
  • System deconvolution
  • Dereverberation or deringing
  • Predictive deconvolution to attenuate multiples
  • Deghosting
  • Spectral whitening or equalizing
  • Amplitude frequency and/or phase shaping
  • Wavelet processing
• Gathering
  • Gather types
• Velocity Determination and Analysis
  • Semblance analysis
• Moveout
  • Normal moveout, dip moveout, and azimuthal moveout
• Static Corrections
  • Preliminary and Residual
• Migration
  • Time versus depth migration
  • Poststack versus prestack migration
  • Specific migration techniques and applications
• Additional Aspects (generally included in other topic discussions)
  • Noise reduction (F-K, tau-p, and F-X)
  • 5D interpolation
  • Reflection versus refraction
• Hands-On Exercises
  • Numerous practical exercises are incorporated throughout the course
  • Exercises include data QC, geophone array, designs based on specific subsurface objectives, raypath modeling, velocity analysis, and comparative interpretation (original data versus reprocessed data).

• Summary and Concluding Remarks
  • The present state and future role of seismic acquisition and processing; and final Q&A session.