Model Based Inversion: Low Frequency Model Importance
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Questions and Answers

What does the reflection coefficient R describe in the context of acoustic inversion?

  • The frequency of the reflected wave
  • The amount of wave energy reflected at the interface between layers (correct)
  • The speed of the incident wave
  • The angle of incidence

    • Which parameter affects the reflection amplitude of a normal-incident P-wave at the interface between elastic half-spaces?

  • Wave frequency
  • Incident wave speed
  • Reflection angle
  • Impedance difference between the half-spaces (correct)

    • What can full stack seismic data, assumed to represent zero-offset traces, allow us to estimate through inversion?

  • Layer thickness
  • Acoustic impedance (correct)
  • Wave frequency
  • Wave velocity

    • What should be considered when choosing a deterministic inversion method for full stack seismic data?

    <p>Level of well control available and desired answer detail</p> Signup and view all the answers

    Which method, also known as Bandlimited Inversion, is considered as a simple form of deterministic inversion?

    <p>Recursive Inversion</p> Signup and view all the answers

    What determines the amount of fine-scale detail needed in the answer when choosing an inversion method?

    <p>Amount of uncertainty quantification required</p> Signup and view all the answers

    What does the Simplicity term Fcontrast aim to achieve in the objective function?

    <p>Create an inverted impedance log with as few reflection coefficients as possible</p> Signup and view all the answers

    How does the Spatial Term Fspatial contribute to the solution?

    <p>Stabilizes the low frequencies</p> Signup and view all the answers

    What effect does a higher S/N ratio have on the inversion solution according to the text?

    <p>Drives the solution by the fit of the synthetic to the seismic data</p> Signup and view all the answers

    Why is it mentioned that increasing all user weights by a similar amount will not change the solution?

    <p>Due to non-uniqueness of the solution</p> Signup and view all the answers

    What does the Trend Term Ftrend primarily stabilize in the inversion process?

    <p>Low frequencies</p> Signup and view all the answers

    How does changing one weight or including an extra misfit function affect the balance of misfit functions?

    <p>Alters the balance and potentially changes the contributions of all functions</p> Signup and view all the answers

    What type of data records both lower and higher frequency than seismic data?

    <p>Well logs</p> Signup and view all the answers

    Which technique can be used for interpolating well logs to create a low frequency model?

    <p>Inverse distance interpolation</p> Signup and view all the answers

    What guides the interpolation process away from wells when well logs are missing?

    <p>RMS velocities</p> Signup and view all the answers

    What is the primary objective of model-based inversion?

    <p>To minimize the misfit between the synthetic model and seismic data</p> Signup and view all the answers

    What is emphasized as important to understand in the context of inversion techniques?

    <p>Quality of the input seismic data</p> Signup and view all the answers

    Which term refers to minimizing the fit between the seismic and the synthetic generated from inverted impedance?

    <p>Cost function</p> Signup and view all the answers

    What is a key factor in evaluating the final result of model-based inversion after multiple iterations?

    <p>'Complications' in seismic data like noise</p> Signup and view all the answers

    Which technique involves updating the elastic attributes of the model iteratively to reduce differences with seismic data?

    <p>'Model based inversion'</p> Signup and view all the answers

    'External drift kriging' is an example of what in relation to creating a low frequency model?

    <p>'Interpolation technique'</p> Signup and view all the answers

    'Sparse Spike inversion algorithm' is associated with which software?

    <p>'Jason'</p> Signup and view all the answers

    What is the purpose of applying the inverse wavelet to a seismic trace?

    <p>To convert it to a reflectivity trace</p> Signup and view all the answers

    What is the main challenge faced when converting reflectivity to impedance?

    <p>Possible phase errors and noise contamination</p> Signup and view all the answers

    What is the purpose of Colored Inversion compared to Recursive Inversion?

    <p>To transform seismic trace into impedance faster</p> Signup and view all the answers

    What is the key assumption made by Sparse Spike Inversion?

    <p>Only large spikes in reflectivity are meaningful</p> Signup and view all the answers

    How does Model Based Inversion differ from Sparse Spike Inversion?

    <p>It solves for reflectivity iteratively based on known seismic data and wavelets</p> Signup and view all the answers

    In the context of the text, why is the low frequency model important for seismic inversion?

    <p>It reconstructs important velocity structure absent in seismic data</p> Signup and view all the answers

    What does Sparse Spike Inversion aim to achieve by finding large spikes in the reflectivity?

    <p>Reproduce the seismic trace with minimum number of reflections</p> Signup and view all the answers

    How does Colored Inversion differ from Bandlimited method?

    <p>Is faster and does not need a good initial model</p> Signup and view all the answers

    What is the main difference between Recursive Inversion and Colored Inversion methodology?

    <p>It is faster and does not require a good initial model</p> Signup and view all the answers

    How does Model Based Inversion tackle random noise in seismic data?

    <p>It solves for reflectivity iteratively by minimizing misfit</p> Signup and view all the answers

    What is a key assumption made in acoustic inversion?

    <p>Stable wavelet that does not change with time</p> Signup and view all the answers

    What do the seismic data show according to the text?

    <p>Interfaces between rock layers</p> Signup and view all the answers

    Why is interpretation challenging in the southeast Asia clastic example?

    <p>Interference due to close vertical positioning of layers</p> Signup and view all the answers

    What is a benefit of acoustic inversion for improved horizon interpretation?

    <p>Attenuation of wavelet sidelobes</p> Signup and view all the answers

    Which data type provides easier analysis of lateral continuity in rock layers?

    <p>Inverted data</p> Signup and view all the answers

    What is a characteristic of the Yellow horizon in the improved horizon interpretation example?

    <p>Valley fill interpretation</p> Signup and view all the answers

    Why is the completion of the Yellow horizon easier in the improved horizon interpretation example?

    <p>Wavelet sidelobes are attenuated</p> Signup and view all the answers

    How does acoustic inversion assist in better prospect identification?

    <p>Enhances contrast between sand layers</p> Signup and view all the answers

    What complicates interpretation in the southeast Asia clastic example?

    <p>Close vertical positioning of contrasting layers within half of a wavelet length.</p> Signup and view all the answers

    What does seismic tuning cause in the lower sand layer according to the text?

    <p>Bright appearance compared to upper sand.</p> Signup and view all the answers

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