Geop 397 - 2.5D Migration

Question 1

Specify the 2 migration domains

Answer 1

time and depth

Question 2

For a given 3D survey, what are the 2 possible positions in the processing sequence for applying migration ?

Answer 2

pre-stack or post-stack

Question 3

Specify 2 methods for applying migration process

Answer 3

time migration - dip events “image”

depth migration- lateral velocity variation

Question 4

How was it determined that 3D refraction statics were beneficial to seismic data quality ?

Answer 4

comparison with elevation statics showed improvements in reflections
NOTE: comparison of Brute stacks.
LHS
1)Elevation statics. Only elevation correction.
2) 1 global velocity function.
(The reflection is not a straight line.

RHS
Elevation and weathering
Static correction (flatter reflections/// BETTER!)

Question 5

Define surface consistent process?

Answer 5

Any process that accounts for surface location of shots or receivers in its computation

Question 6

List 4 surface consistent processes

Answer 6

3D surface consistent amplitude compensation
3D surface consistent spiking deconvolution
3D residual statics
3D refraction statics

Question 7

what process must be applied to field data if the seismic source is VIBROSEIS?

Answer 7

cross-correlation. Output data is zero phase

Question 8

What process what applied immediately prior to the application of spiking deconvolution

Answer 8

Conversion of zero phase data to minimum phase.

Deconvolution assumes input data is minimum phase.

Question 9

What’s the difference between F-X process and F-XY process ?

Answer 9

FX is 2D

F-XY is 3D