REVERSE TIME MIGRATION BACK-SCATTERING NOISE REMOVAL USING DECOMPOSED WAVEFIELD DIRECTIVITY

• US 20120051176A1
• Filed: 08/31/2010
• Published: 03/01/2012
• Est. Priority Date: 08/31/2010
• Status: Abandoned Application

• Current Assignee: Chevron USA Incorporated (Chevron Corp.)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.)
• Inventors: Liu, Wei
• Application Number:
  US12/872,927
• Publication Number:
  US 20120051176A1
• Time in Patent Office: Days
• US Class Current: 367/38
• CPC Class Codes: G01V 1/28 Processing seismic data, e.g. for interpretation or for event detection G01V1/48 takes precedence
• CPC Class Codes: G01V 2210/30 Noise handling trace signal pre-filtering G01V2210/20
• CPC Class Codes: G01V 2210/51 Migration
• CPC Class Codes: G01V 2210/67 Wave propagation modeling
• CPC Class Codes: G01V 2210/679 Reverse-time modeling or coalescence modelling, i.e. starting from receivers

Abstract

Images of a subsurface region may be generated in conjunction with reverse time migration with reduced or no backscattering noise. Two or more wavefields may be decomposed to produce two or more corresponding decomposed wavefields. The two or more decomposed wavefields may include a source wavefield and a receiver wavefield. Directivity of the two or more decomposed wavefields may be determined to produce corresponding direction-dependent components of the two or more decomposed wavefields. One or more of the direction-dependent components of one or more decomposed source wavefields may be cross-correlated with one or more of the direction-dependent components of one or more corresponding decomposed receiver wavefields. An image of the subsurface region may be generated based on the cross-correlation.

Claims

1. A computer-implemented method for generating images of a subsurface region, the method comprising:

decomposing two or more wavefields to produce two or more corresponding decomposed wavefields, wherein the two or more wavefields include a source wavefield and a receiver wavefield;

determining directivity of the two or more decomposed wavefields to produce corresponding direction-dependent components of the two or more decomposed wavefields;

cross-correlating one or more of the direction-dependent components of one or more decomposed source wavefields with one or more of the direction-dependent components of one or more decomposed receiver wavefields; and

generating an image of the subsurface region based on the cross-correlation.

2. The method of claim 1, wherein decomposing the two or more wavefields includes performing a numerical transformation on the one or more wavefields.

3. The method of claim 2, wherein the numerical transformation is a fast Fourier transformation.

4. The method of claim 1, wherein a plurality of time-states of individual ones of the two or more decomposed wavefields are utilized in determining directivity of the two or more decomposed wavefields.

5. The method of claim 1, wherein generated image is devoid backscattering noise.

6. A system configured to generate images of a subsurface region, the system comprising:

one or more processors configured to execute computer program modules, the computer program modules comprising;

a wavefield decomposition module configured to decompose two or more wavefields to produce two or more corresponding decomposed wavefields, wherein the two or more wavefields include a source wavefield or a receiver wavefield;

a wavefield directivity determination module configured to determine directivity of the two or more decomposed wavefields to produce corresponding direction-dependent components of the two or more decomposed wavefields;

a cross-correlation module configured to cross-correlate one or more of the direction-dependent components of one or more decomposed source wavefields with one or more of the direction-dependent components of one or more decomposed receiver wavefields; and

an image generation module configured to generate an image of the subsurface region based on the cross-correlation performed by the cross-correlation module.

7. The system of claim 6, wherein the wavefield decomposition module is further configured to decompose the two or more wavefields, at least in part, by performing a numerical transformation on the two or more wavefields.

8. The system of claim 7, wherein the numerical transformation is a fast-Fourier transformation.

9. The system of claim 6, wherein the wavefield directivity determination module is further configured to utilize a plurality of time-states of individual ones of the two or more decomposed wavefields to determine directivity of the two or more decomposed wavefields.

10. The system of claim 6, wherein the generated image is devoid backscattering noise.

11. A computer-readable storage medium having instructions embodied thereon, the instructions being executable by a processor to perform a method for generating images of a subsurface region, the method comprising:

decomposing two or more wavefields to produce two or more corresponding decomposed wavefields, wherein the two or more wavefields include a source wavefield and a receiver wavefield;

determining directivity of the two or more decomposed wavefields to produce corresponding direction-dependent components of the two or more decomposed wavefields;

cross-correlating one or more of the direction-dependent components of one or more decomposed source wavefields with one or more of the direction-dependent components of one or more decomposed receiver wavefields; and

generating an image of the subsurface region based on the cross-correlation.

12. The computer-readable storage medium of claim 11, wherein decomposing the two or more wavefields includes performing a numerical transformation on the one or more wavefields.

13. The computer-readable storage medium of claim 12, wherein the numerical transformation is a fast Fourier transformation.

14. The computer-readable storage medium of claim 11, wherein a plurality of time-states of individual ones of the two or more decomposed wavefields are utilized in determining directivity of the two or more decomposed wavefields.

15. The computer-readable storage medium of claim 11, wherein generated image is devoid backscattering noise.