Generating pseudo pressure wavefields utilizing a warping attribute

1. A method of manufacturing a geophysical data product, the method comprising:

accessing a representation of an up-going pressure wavefield and a down-going pressure wavefield;

determining a warping attribute based at least in part on a difference between the up-going pressure wavefield and the down-going pressure wavefield;

determining a pseudo down-going pressure wavefield based on the up-going pressure wavefield and the warping attribute; and

using the pseudo down-going pressure wavefield to generate a modified record of geophysical data, wherein the warping attribute enables the pseudo down-going pressure wavefield to be generated from the up-going pressure wavefield without persistently storing a record of the down-going pressure wavefield, thereby reducing computational resources required to generate the modified record of geophysical data; and

storing the modified record of geophysical data on a non-transitory computer readable memory medium, thereby completing the manufacture of the geophysical data product.

2. The method of claim 1 , wherein the warping attribute is multi-dimensional.

3. The method of claim 2 , wherein the warping attribute comprises a time dimension, a channel number on a streamer dimension, and a streamer number dimension.

4. The method of claim 1 , wherein using the pseudo down-going pressure wavefield to generate the modified record of geophysical data comprises imaging subsurface structure using separated wavefields.

5. The method of claim 1 , wherein using the pseudo down-going pressure wavefield to generate the modified record of geophysical data comprises performing multiple prediction.

6. The method of claim 1 , further comprising:

prior to determining the pseudo down-going pressure wavefield, performing pre-conditioning on the up-going pressure wavefield without performing pre-conditioning on the down-going pressure wavefield, wherein determining the pseudo down-going pressure wavefield based on the up-going pressure wavefield reflects the pre-conditioning.

7. The method of claim 1 , further comprising:

applying an obliquity correction with acoustic scaling to the pseudo down-going pressure wavefield to obtain a pseudo down-going particle motion wavefield; and

using the pseudo down-going particle motion wavefield to perform geophysical data calculations.

8. A computer system configured to generate a noise-reduced image of subsurface geology from seismic data, the computer system comprising:

one or more processors;

a non-transitory computer readable memory medium;

wherein the one or more processors are configured to execute instructions stored on the non-transitory computer readable memory medium to implement:

means for receiving an up-going pressure wavefield and a down-going pressure wavefield, wherein the pressure wavefields comprise seismic data received from a seismic data acquisition system located beneath a free-surface of a body of water;

means for determining a warping attribute based at least in part on a difference between the up-going pressure wavefield and the down-going pressure wavefield;

means for determining a pseudo down-going pressure wavefield based on the up-going pressure wavefield and the warping attribute;

generation of a modified record of geophysical data using the pseudo down-going pressure wavefield; and

storage of a modified record of geophysical data on a non-transitory computer readable memory medium, thereby generating the noise-reduced image of subsurface geology.

9. The computer system of claim 8 , wherein the warping attribute is a multidimensional warping attribute comprising a time dimension, a channel number on a streamer dimension, and a streamer number dimension.

10. The computer system of claim 8 , wherein the instructions are further executable to:

prior to determining the pseudo down-going pressure wavefield, perform pre-conditioning on the up-going pressure wavefield without performing pre-conditioning on the down-going pressure wavefield, wherein determining the pseudo down-going pressure wavefield based on the up-going pressure wavefield reflects the pre-conditioning.

11. The computer system of claim 8 , wherein the instructions are further executable to:

apply an obliquity correction to the pseudo down-going pressure wavefield to obtain a pseudo down-going particle motion wavefield; and

use the pseudo down-going particle motion wavefield to perform geophysical data calculations.

12. The computer system of claim 8 , wherein the warping attribute comprises a time shift for each of a plurality of samples and each of a plurality of traces associated with the up-going and down-going pressure wavefields.

13. The computer system of claim 8 , wherein the up-going pressure wavefield and the down-going pressure wavefield are obtained from a pressure wavefield detected by receivers of a seismic data-acquisition system.

14. The computer system of claim 8 , wherein the instructions are further executable to compare a magnitude of the warping attribute to a predetermined threshold; and

wherein, based on a determination that the magnitude of the warping attribute is less than the predetermined threshold, the means for determining the pseudo down-going pressure wavefield outputs the up-going pressure wavefield as the pseudo down-going pressure wavefield without applying the warping attribute.

15. A non-transitory computer-readable memory medium storing program instructions which, when executed by a processor of a computer system, cause the computer system to at least:

access a representation of a down-going pressure wavefield and an up-going pressure wavefield;

determine a warping attribute based at least in part on a difference between the down-going pressure wavefield and the up-going pressure wavefield;

determine a pseudo up-going pressure wavefield based on the down-going pressure wavefield and the warping attribute;

use the pseudo up-going pressure wavefield to generate a modified record of geophysical data; and

store the modified record of geophysical data on the non-transitory computer-readable memory medium.

16. The non-transitory computer-readable memory medium of claim 15 , wherein the warping attribute is a multidimensional warping attribute comprising a time dimension, a channel number on a streamer dimension, and a streamer number dimension.

17. The non-transitory computer-readable memory medium of claim 15 , wherein the program instructions are further executable to cause the computer system to:

prior to determining the pseudo up-going pressure wavefield, perform pre-conditioning on the down-going pressure wavefield without performing pre-conditioning on the up-going pressure wavefield, wherein determining the pseudo up-going pressure wavefield based on the down-going pressure wavefield reflects the pre-conditioning.

18. The non-transitory computer-readable memory medium of claim 15 wherein the program instructions are further executable to cause the computer system to:

apply an obliquity correction to the pseudo up-going pressure wavefield to obtain a pseudo up-going particle motion wavefield; and

use the pseudo up-going particle motion wavefield to perform geophysical data calculations.

19. The non-transitory computer-readable memory medium of claim 15 , wherein the warping attribute comprises a time shift for each of a plurality of samples and each of a plurality of traces associated with the up-going and down-going pressure wavefields.

20. The non-transitory computer-readable memory medium of claim 15 , wherein the up-going pressure wavefield and the down-going pressure wavefield are obtained from a pressure wavefield detected by receivers of a seismic data-acquisition system.

21. The non-transitory computer-readable memory medium of claim 15 , wherein the program instructions are further executable to cause the computer system to compare a magnitude of the warping attribute to a predetermined threshold; and

wherein to determine the pseudo up-going pressure wavefield, based on a determination that the magnitude of the warping attribute is less than the predetermined threshold, the program instructions are further executable to output the down-going pressure wavefield as the pseudo up-going pressure wavefield without applying the warping attribute.