Well Log Quality Check for Seismic Inversion
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What is the purpose of building a low frequency model in seismic inversion?

  • To recover absolute acoustic impedance (correct)
  • To identify the frequency spectrum of seismic data
  • To improve the resolution of seismic images
  • To determine relative impedances between layers

    • Why are low frequencies important in seismic inversion?

  • They allow for the calculation of relative impedances
  • They help determine the frequency spectrum of seismic data
  • They improve the interpretation of seismic horizons
  • They enable the recovery of absolute acoustic impedance (correct)

    • What do acoustic impedance logs contain that seismic data lacks?

  • Stratigraphic framework
  • Full frequency spectrum (correct)
  • Relative impedances
  • Low-frequency trends

    • Which step is NOT involved in creating a Low Frequency Model?

    <p>Identifying the high-frequency components in seismic data</p> Signup and view all the answers

    Why can only relative impedances be determined without low frequencies in seismic data?

    <p>As a result of band-limitation in seismic data</p> Signup and view all the answers

    What role does a low-frequency model serve as in the Model Based inversion process?

    <p>Providing a starting point for inversion</p> Signup and view all the answers

    What is the reason for only relative impedances being determined without a low-frequency model?

    <p>Band-limited nature of seismic data</p> Signup and view all the answers

    How can the issue of spurious or non-calibrated data be addressed?

    <p>Reviewing the petrophysical editing and calibration of the relevant well</p> Signup and view all the answers

    What must be consistent with the geological context?

    <p>Spatial variation of elastic properties</p> Signup and view all the answers

    When is seismic interval velocity included in the Low Frequency Model?

    <p>As secondary data to guide interpolation away from wells</p> Signup and view all the answers

    What does including a low-frequency model allow in terms of acoustic impedance recovery?

    <p>Recovery of absolute acoustic impedance</p> Signup and view all the answers

    How are seismic velocities integrated in the creation of a Low Frequency Model?

    <p>As a primary component when well logs are unavailable</p> Signup and view all the answers

    What is a key consideration when building a good low frequency model?

    <p>Editing and correlating selected wells</p> Signup and view all the answers

    In Low Frequency Model creation, what is the purpose of determining the structural or stratigraphic grid framework?

    <p>To define an area representative grid</p> Signup and view all the answers

    When interpolating low-frequency well data between consecutive horizons, what should be considered if the seismic events are parallel to the base horizon?

    <p>Thickness following base horizon with constant thickness</p> Signup and view all the answers

    How can we estimate the low frequency needed in the Low Frequency Model?

    <p>Filtering logs to retain information not captured by seismic data</p> Signup and view all the answers

    What is the main purpose of applying a low pass filter to seismic sections?

    <p>To check for consistent amplitudes in seismic data</p> Signup and view all the answers

    Why is it necessary to establish a well-defined structural grid in Low Frequency Model building?

    <p>To ensure geological contrasts align with seismic reflectors</p> Signup and view all the answers

    Which step is NOT involved in creating a Low Frequency Model?

    <p>Velocity analysis</p> Signup and view all the answers

    Why are decisions needed regarding extrapolation above the shallowest log point and below the deepest log point when building a Low Frequency Model?

    <p>Because well logs rarely extend to the surface or penetrate to depth.</p> Signup and view all the answers

    What is a key consideration when using seismic velocities as an external drift?

    <p>Ensuring coherence with well velocities</p> Signup and view all the answers

    In the context of interpolation methods, what does Kriging rely on to control spatial correlation?

    <p>Variograms</p> Signup and view all the answers

    What is a variogram used for in geostatistics?

    <p>Analyzing spatial variability and correlation</p> Signup and view all the answers

    What do isotropic variograms have in common?

    <p>Equal ranges in all directions</p> Signup and view all the answers

    Why is it important to choose variogram parameters based on geology and structures?

    <p>To account for fault directions and sizes</p> Signup and view all the answers

    What should be checked before inversion to ensure the final result depends greatly on the initial model?

    <p>Vertical variation</p> Signup and view all the answers

    What is the primary function of Low Frequency Model interpolation?

    <p>To interpolate filtered well logs within a grid</p> Signup and view all the answers

    Which factor influences the choice between isotropic and anisotropic variograms?

    <p>Fault direction and block size</p> Signup and view all the answers

    'Collocated co-kriging' uses which type of variable as a trend in interpolation?

    <p>'Seismic velocity'</p> Signup and view all the answers

    'Inverse distance interpolation' and 'Kriging' are common techniques for what process?

    <p>'Interpolating filtered well logs'</p> Signup and view all the answers

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