397 - True Depth Conversion

Question 1

State 4 expected deliverables of depth conversion project

Answer 1

• seismic data volume (SEGY) in depth instead of time
• maps/computer grids of depth from seismic and wells
• 2D velocity model or 3D cube data volume
• uncertainty analysis of final “best result”

Question 2

Briefly explain depth migration

Answer 2

imaging of subsurface structure (imaging issue)

Question 3

briefly explain depth conversion

Answer 3

calibration of seismic to subsurface model (calibration issue)

Question 4

What is the purpose of depth conversion?

Answer 4

remove structural ambiguity inherent in time and verify structure

Question 5

List 2 kinds of depth conversion

Answer 5

• direct time-depth conversion

- velocity modeling for depth conversion

Question 6

State 2 criteria to evaluate accuracy and reliability of a depth conversion

Answer 6

• tie existing wells to verify if velocities are accurate

- blind test to accurately predict depths at new well locations

Question 7

what is another reason for velocity misties (aside from velocity anisotropy)

Answer 7

many velocity models can produce equivalent image (or similar answer).
The velocity model is therefore not unique

Question 8

one possible solution to velocity mistie

Answer 8

incorporate well date into velocity model . you control seismic date to be more accurate

Question 9

why are seismic stacking velocities picked on the “fast side” of the velocity function?

Answer 9

to discriminate against multiples.