INVERSION Flashcards
(15 cards)
what are the kinds of inversion?
pre-stack and post-stack inversion
What are the inputs to post-stack inversion?
- well logs (sonic and density)
- seismic data (3D stack data)
- horizons (5-7)
What is the output of post-stack inversion?
P-impedence
What’s the workflow for post-stack inversion?
- Load well log seismic data and horizons
- well to seismic correlation
- extract the wavelet
- generate low frequency model
- inversion analysis at the well section
- run full inversion on 3D data set
What are the inputs to pre-stack inversion?
- well log (sonic, dipole sonic (s-wave velocity)
and density - seismic data (fully processed and 3D migrated ) cdp gathers
- horizons
What is the output of pre-stack inversion?
- P-impedence
- S-impedence
- density
What is the workflow for pre-stack inversion?
- Load well log seismic data and horizons
- well to seismic correlation
- extract the wavelet
- generate low frequency model
- inversion analysis at the well section
- run full inversion on 3D data set
Formula for Convolution Model ?
Rc X w(t) = s(t)
Formula for Reverse of Convolution Model?
S(t) * 1/w(t) = Rc –> AI –> p1V1
What are the x-ys of Amplitude Spectrum Graph?
- Amplitude on the Y axis
- frequency on the X axis
What are the axes of the Phase Spectrum graph?
- X axis is frequency
- Y axis 0 on the x axis. Above and below are + and -
Typs of Post-Stack Inversion?
- Model Based (start with low frequency model . iteratively update it.
- Coloured —- no model
- Band limited — limited frequency range.
How can you recognize post-stack inversion?
incident angle is 0 or normal incidence
How can you recognize pre-stack inversion?
incident angel is > 0 degrees to critical angle (approx 30-45 degrees)
Formulae to remember
AI = p x V Rc = (P2V2 - P1V1)/(P2V2+P1V1)
