Content of topics in 3D Seismic Survey Design and Quality Control

Introduction to Seismic Acquisition

  • The seismic experiment and basic measurements
  • Characteristics of seismic data
  • Definitions of seismic trace, record, coverage, section and cube
  • Major steps in seismic exploration
  • Role of seismic in the reservoir life cycle
  • Exercise on acquisition pitfalls.

Seismic Wave Propagation

  • Stress, strain, elastic moduli and the wave equation
  • P-wave and S-wave velocity in terms of elastic moduli
  • Raypaths, wavefronts, Huygen's principle, Snell's law
  • Reflection, refraction and diffractions
  • Relationships between porosity, depth of burial, velocity, density, incidence angle and reflection strength
  • Refraction seismic method with exercise
  • Fourier analysis
  • The convolutional trace model
  • Spectral properties of the seismic wavelet and vertical resolution
  • Fresnel zone and lateral resolution
  • Bin size, bandwidth and resolution
  • Geometric spreading and absorption
  • Exercises on vertical and lateral resolution

Signal Analysis

  • Sampling of signals in time and space
  • The Nyquist criteria and the causes of aliasing
  • Fourier analysis to convert signals to their spectral components
  • Wavelet phase and its effect on wavelet shape
  • F-K transform and apparent velocity
  • Relationship between seismic events and their F-K transform
  • The linear Radon transform and the tau-p domain
  • Exercises on spatial aliasing

Migration principles

  • Purpose and principles of migration
  • Elements required for accurate migration
  • Types of migration/imaging techniques
  • Geometric rules for migration

Basic processing steps

  • Field statics and refraction statics
  • Velocity analysis and stacking
  • Deconvolution
  • Multiple elimination
  • Static corrections
  • Post-stack and pre-stack time migration and depth migration

Seismic Acquisition Principles

  • Land, marine, transition zone, multi-component, ocean bottom, borehole and 4D seismic acquisition
  • Definitions of acquisition parameters
  • Identifying seismic signals and noise
  • The causes and effects of noise
  • Noise suppression with field arrays
  • The seismic acquisition process and cost overview
  • The survey design workflow: E&P company perspective
  • Exercises on identifying seismic signals and noise from field records and field array design

Seismic Survey Design

  • Introduction to Survey Design
  • Illumination and illumination attributes
  • Acquisition geometries
  • Trace gather types
  • Offset and azimuth distribution and fold requirements
  • Shotpoint and receiver interval
  • Binning, spatial aliasing, fold and bin size
  • Migration aperture
  • Survey orientation
  • Acquisition footprint
  • Workshop on designing a survey using existing seismic data, maps and geological data

Acquisition Implementation and Operations

  • Positioning principles
  • The GPS revolution
  • Marine cable positioning, compasses and depth control
  • Marine airgun characteristics; airgun array design
  • Explosive sources
  • Land vibrator characteristics
  • Vibroseis sweep, cross-correlation, Klauder wavelet
  • Hydrophones, geophones, MEMS and coupling
  • Recording systems
  • Land and marine acquisition quality control

Evaluation of Survey Design

  • Subsurface imaging objective setting
  • Acquisition definitions and concepts
  • Parameter setting principles
  • Practical factors in 3D survey design

Acquisition footprint

  • Origins of the acquisition footprint
  • Analysis of the acquisition footprint
  • How to reduce the acquisition footprint

Multi-component and OBC acquisition

  • Benefits of multi-component acquisition
  • Benefits of seabed acquisition
  • Acquisition issues: recording geometries, multi-component detection
  • PS-waves: generation, properties, data handling and processing

Marine acquisition

  • Marine source modeling
  • Quality control of marine acquisition
  • 4D issues of marine acquisition
  • Multi-azimuth and wide-azimuth marine acquisition

Land acquisition parameters

  • Positioning: real time kinematic versus pseudo-range corrections
  • Survey geometries
    1. narrow versus wide / single-line roll versus multi-line roll
    2. sparse versus full fold
  • Channel counts
  • Holistic approach: need to consider processing/interpretation work flow

Land receivers

  • MEMS, GAC's and geophones
  • Receiver arrays and single sensors

Land sources

  • Vibroseis principles and operations
    1. fundamental force
    2. control electronics
    3. productivity enhancements: slip-sweep, HPVA, cascaded sweeps, HFVS
  • Impulsive sources: dynamite and airgun

Land acquisition QC

  • Positioning QC: Survey QC, LMO
  • Noisy traces, bad records
  • Time breaks
  • Vibrator QC: correlation and vibrator output
  • Role of field processing

Near surface corrections

  • Upholes, LVL surveys, ground viscosity measurements
  • Limitations