1. Migration – Correcting for Location
Sweep Ellipse S R
Unmigrated energy on single trace... S R
Sweep Ellipse OR
SLIDE 18
There is a data processing procedure that we call seismic migration that corrects this mis-positioning problem
For each trace, the computer swings arcs (based on the velocities) to find all the possible locations from which a reflection could have originated
To illustrate, consider the black peak circled by a green oval in the upper left – we will call this the “green” peak
In the lower left we have swung arcs to define all the possible reflections points
The dotted green arc shows the possible reflections points for the “green” peak
On the right, we show 3 possible shot-receiver pairs that could be the reason for the “green” peak
But which one is correct – of these 3 or some other case?
Seismic migration will answer this for us
...spread to all possible locations of origin S R
Sweep Ellipse OR
Courtesy of ExxonMobil
L 5 – Seismic Method