Methods and systems for optimizing generation of seismic images

1. A method to generate an image of a subterranean formation, the method comprising:

receiving a gather of receiver seismic data generated by receivers of a seismic data acquisition system;

smoothing amplitudes of each trace of the gather of receiver seismic data to generate a smoothed-amplitude gather, the smoothed-amplitude gather having smoothed-amplitude traces, each smoothed-amplitude trace corresponding to a trace of the gather of receiver seismic data;

stacking the traces of the gather of receiver seismic data to generate a noise-reduced trace, wherein each amplitude of the noise-reduced trace is calculated as a sum of amplitudes of the traces of the gather of receiver seismic data weighted by smoothed amplitudes of corresponding smoothed-amplitude traces of the smoothed-amplitude gather; and

generating an image of the subterranean formation based at least in part on the noise-reduced traces, the image revealing subsurface structural information about the subterranean formation.

2. The method of claim 1 , wherein calculating the smoothed-amplitude gather further comprises for each sample coordinate of the gather,

centering a sliding window on the sample coordinate, the sliding window containing amplitudes of each trace in the gather; and

for each trace, calculating a smoothed amplitude at the sample coordinate as a weighted sum of amplitudes of the trace within the sliding window.

3. The method of claim 1 , wherein stacking traces of the gather to generate the noise-reduced trace further comprises identifying reflectors of the gather as one of horizontal and non-horizontal.

4. The method of claim 3 further comprising when the reflectors are identified as horizontal, for each sample coordinate, calculating an amplitude of the noise-reduced trace as a summation of each amplitude of the gather multiplied by a corresponding smoothed amplitude of the smoothed-amplitude gather raised to a power, the summation divided by a sum of smoothed amplitudes of the smoothed-amplitude gather at the same sampled coordinate, each smoothed amplitude raised to the power.

5. The method of claim 3 further comprising when the reflectors are identified as non-horizontal,

for each sample coordinate that corresponds to a central spatial coordinate in a non-horizontal reflector,

calculating an amplitude of the noise-reduced trace as a summation of each amplitude with spatial coordinates that lie in the non-horizontal reflector multiplied by a corresponding smoothed amplitude of the smoothed-amplitude gather raised to a power that lie in the non-horizontal reflector of the corresponding smoothed-amplitude gather, the summation divided by a sum of smoothed amplitudes of the smoothed-amplitude gather that lie the non-horizontal reflector, each smoothed amplitude raised to the power; and

for each sample coordinate that does not have corresponding spatial coordinates in one of the non-horizontal reflectors, setting the amplitude to zero in the noise-reduced trace.

6. The method of claim 1 executed on a programmable computer programmed to perform the method.

7. The method of claim 1 further comprises storing the noise-reduced traces in one or more data-storage devices.

8. The method of claim 1 , wherein the noise-reduced traces form a geophysical data product, further comprising recording the geophysical data product on a physical, non-volatile computer-readable medium suitable for importing onshore.

9. The method of claim 8 , further comprising performing geophysical analysis onshore on the geophysical data product.

10. A computer system to generate an image of a subterranean formation, the system comprising:

one or more processors;

one or more data-storage devices; and

a routine stored in one or more of data-storage devices and executed by the one or more processors, the routine directed to

retrieving seismic data generated by receivers of a seismic data acquisition system from the one or more data-storage devices;

smoothing amplitudes of each trace of the gather of receiver seismic data to generate a smoothed-amplitude gather, the smoothed-amplitude gather having smoothed-amplitude traces, each smoothed-amplitude trace corresponding to a trace of the gather of receiver seismic data;

stacking the traces of the gather of receiver seismic data to generate a noise-reduced trace, wherein each amplitude of the noise-reduced trace is calculated as a sum of amplitudes of the traces of the gather of receiver seismic data weighted by smoothed amplitudes of corresponding smoothed-amplitude traces of the smoothed-amplitude gather; and

generating an image of the subterranean formation based at least in part on the noise-reduced traces, the image revealing subsurface structural information about the subterranean formation.

11. The system of claim 10 , wherein calculating the smoothed-amplitude gather further comprises for each sample coordinate of the gather,

centering a sliding window on the sample coordinate, the sliding window containing amplitudes of each trace in the gather; and

for each trace, calculating a smoothed amplitude at the sample coordinate as a weighted sum of amplitudes of the trace within the sliding window.

12. The system of claim 10 , wherein stacking traces of the gather to generate the noise-reduced trace further comprises identifying reflectors of the gather as one of horizontal and non-horizontal.

13. The system of claim 12 further comprising when the reflectors are identified as horizontal, for each sample coordinate, calculating an amplitude of the noise-reduced trace as a summation of each amplitude of the gather multiplied by a corresponding smoothed amplitude of the smoothed-amplitude gather raised to a power, the summation divided by a sum of smoothed amplitudes of the smoothed-amplitude gather at the same sampled coordinate, each smoothed amplitude raised to the power.

14. The system of claim 12 further comprising when the reflectors are identified as non-horizontal,

for each sample coordinate that corresponds to a central spatial coordinate in a non-horizontal reflector,

calculating an amplitude of the noise-reduced trace as a summation of each amplitude with spatial coordinates that lie in the non-horizontal reflector multiplied by a corresponding smoothed amplitude of the smoothed-amplitude gather raised to a power that lie in the non-horizontal reflector of the corresponding smoothed-amplitude gather, the summation divided by a sum of smoothed amplitudes of the smoothed-amplitude gather that lie the non-horizontal reflector, each smoothed amplitude raised to the power; and

for each sample coordinate that does not have corresponding spatial coordinates in one of the non-horizontal reflectors, setting the amplitude to zero in the noise-reduced trace.

15. The system of claim 10 executed on a programmable computer programmed to perform the method.

16. The system of claim 10 further comprises storing the noise-reduced traces in one or more data-storage devices.

17. The system of claim 10 , wherein the noise-reduced traces form a geophysical data product, further comprising recording the geophysical data product on a physical, non-volatile computer-readable medium suitable for importing onshore.

18. The system of claim 17 , further comprising performing geophysical analysis onshore on the geophysical data product.

19. A non-transitory computer-readable medium having machine-readable instructions encoded thereon for enabling one or more processors of a computer system to perform the operations of

retrieving seismic data generated by receivers of a seismic data acquisition system from the one or more data-storage devices;

smoothing amplitudes of each trace of the gather of receiver seismic data to generate a smoothed-amplitude gather, the smoothed-amplitude gather having smoothed-amplitude traces, each smoothed-amplitude trace corresponding to a trace of the gather of receiver seismic data;

stacking the traces of the gather of receiver seismic data to generate a noise-reduced trace, wherein each amplitude of the noise-reduced trace is calculated as a sum of amplitudes of the traces of the gather of receiver seismic data weighted by smoothed amplitudes of corresponding smoothed-amplitude traces of the smoothed-amplitude gather; and

generating an image of the subterranean formation based at least in part on the noise-reduced traces, the image revealing subsurface structural information about the subterranean formation.

20. The computer-readable medium of claim 19 , wherein calculating the smoothed-amplitude gather further comprises for each sample coordinate of the gather,

centering a sliding window on the sample coordinate, the sliding window containing amplitudes of each trace in the gather; and

for each trace, calculating a smoothed amplitude at the sample coordinate as a weighted sum of amplitudes of the trace within the sliding window.

21. The computer-readable medium of claim 19 , wherein stacking traces of the gather to generate the noise-reduced trace further comprises identifying reflectors of the gather as one of horizontal and non-horizontal.

22. The computer-readable medium of claim 21 further comprising when the reflectors are identified as horizontal, for each sample coordinate, calculating an amplitude of the noise-reduced trace as a summation of each amplitude of the gather multiplied by a corresponding smoothed amplitude of the smoothed-amplitude gather raised to a power, the summation divided by a sum of smoothed amplitudes of the smoothed-amplitude gather at the same sampled coordinate, each smoothed amplitude raised to the power.

23. The computer-readable medium of claim 21 further comprising when the reflectors are identified as non-horizontal,

for each sample coordinate that corresponds to a central spatial coordinate in a non-horizontal reflector,

calculating an amplitude of the noise-reduced trace as a summation of each amplitude with spatial coordinates that lie in the non-horizontal reflector multiplied by a corresponding smoothed amplitude of the smoothed-amplitude gather raised to a power that lie in the non-horizontal reflector of the corresponding smoothed-amplitude gather, the summation divided by a sum of smoothed amplitudes of the smoothed-amplitude gather that lie the non-horizontal reflector, each smoothed amplitude raised to the power; and

for each sample coordinate that does not have corresponding spatial coordinates in one of the non-horizontal reflectors, setting the amplitude to zero in the noise-reduced trace.

24. The computer-readable medium of claim 19 executed on a programmable computer programmed to perform the method.

25. The computer-readable medium of claim 19 further comprises storing the noise-reduced traces in one or more data-storage devices.

26. The computer-readable medium of claim 19 , wherein the noise-reduced traces form a geophysical data product, further comprising recording the geophysical data product on a physical, non-volatile computer-readable medium suitable for importing onshore.

27. The computer-readable medium of claim 26 , further comprising performing geophysical analysis onshore on the geophysical data product.