Methods for earth modeling and seismic imaging using interactive and selective updating

• US 20060056272A1
• Filed: 09/13/2004
• Published: 03/16/2006
• Est. Priority Date: 09/13/2004
• Status: Active Grant

• Current Assignee: Chevron USA Incorporated (Chevron Corp.)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.)
• Inventors: Hill, N. Ross
• Granted Patent: US 7,480,206 B2
• Time in Patent Office: Days
• US Class Current: 367/73
• CPC Class Codes: G01V 1/282 Application of seismic models, synthetic seismograms
• CPC Class Codes: G01V 1/30 Analysis G01V1/50 takes precedence
• CPC Class Codes: G01V 2210/66 Subsurface modeling

Abstract

A method for creating an enhanced seismic image is described. Seismic data is acquired from a seismic survey conducted over a subterranean region. The seismic data is transformed into energy components, preferably Gaussian beam components. An earth model is created which is comprised of lens elements. The set of energy components is propagated or migrated through the lens elements to form image components which are combined into a seismic image. A target is identified in the seismic image for image enhancement. Ray tracing may be used to select the trial set of lens elements to be updated and to select a subset of energy components. The subset of energy components is propagated through updated earth model to form updated image components. The seismic image is updated by replacing image components with updated image components which are formed from the subset of selected energy components. This subset is ideally greatly reduced in size relative to the overall number of energy components, i.e., beam components.

Claims

1. A method for creating an enhanced seismic image, the method comprising:

(a) acquiring seismic data from a seismic survey conducted over a subterranean region;

(b) transforming the seismic data into energy components;

(c) creating an earth model representative of the subterranean region, the earth model including lens elements having propagation properties affecting energy propagation through the lens elements;

(d) propagating the energy components through the lens elements to form image components which are combined into a seismic image;

(e) identifying a target in the seismic image for image enhancement;

(f) selecting and updating propagation properties of a trial set of lens elements which may affect imaging of the target;

(g) selecting a subset of energy components which may affect imaging of the target;

(h) propagating the subset set of energy components through the earth model to form updated image components;

(i) updating the seismic image by replacing image components of the current seismic image with the updated image components; and

(j) repeating steps (e)-(i) until the seismic image is satisfactorily enhanced.

2. The method of claim 1 wherein:

the energy components are beam components.

3. The method of claim 2 wherein:

the beam components are Gaussian beam components.

4. The method of claim 1 wherein:

the energy components includes any partitioning of the seismic data including shot profiles, common offset data, common midpoint data and plane wave energy components.

5. The method of claim 1 wherein:

the propagation of the energy components through the lens elements to form image components is computed using beam migration.

6. The method of claim 1 wherein:

the trial set of lens elements are selected using ray tracing.

7. The method of claim 6 wherein:

the ray tracing utilizes a two-point ray trace search.

8. The method of claim 6 wherein:

the ray tracing utilizes normal ray tracing.

9. The method of claim 1 wherein:

the trial set of lens elements are selected by visual inspection.

10. The method of claim 1 wherein:

energy components are selected using a directed-aperture.

11. The method of claim 1 wherein:

energy components are selected using a migration aperture.

12. The method of claim 1 wherein:

the subset of energy components are selected using ray tracing.

13. The method of claim 1 wherein:

the step of selecting a subset of energy components includes selecting a trial set of energy components that have ray paths that pass within a predetermined distance of the target prior to updating of the lens elements.

14. The method of claim 1 wherein:

the step of selecting a subset of energy components includes selecting a trial set of energy components each having a ray path that passes through at least one of the updated lens elements.

15. The method of claim 1 wherein:

the step of selecting a subset of energy components includes selecting a trial set of energy components that each have a ray path that passes within a predetermined distance of the target and each ray path passes through at least one of the updated lens elements.

16. The method of claim 1 wherein:

the step of selecting a subset of energy components includes propagating the trial set of energy components through the updated earth model to create updated ray paths for the trial set of energy components.

17. The method of claim 16 wherein:

the subset of energy components is selected from the trial set of energy components which touch the target and have ray paths that pass through at least one of the updated lens elements.

18. The method of claim 1 wherein:

the steps (e)-(i) are computed within a single interactive software application.

19. A method for enhancing a seismic image comprising:

(a) creating a seismic image using seismic energy components and an earth model comprising elements to form image components which are summed to form the seismic image;

(b) identifying a target in the seismic image which is to be enhanced;

(c) updating select elements in the earth model;

(d) selecting a subset of energy components from the energy components of step (a);

(e) propagating the subset of energy components through the updated earth model to create updated image components; and

(f) replacing current image components with the updated image components to create an enhanced seismic image.

20. The method of claim 19 wherein:

the energy components are beam components.

21. A method for enhancing a seismic image comprising:

(a) creating a seismic image using an earth model comprising lens elements and seismic data;

(b) update lens elements in the earth model;

(c) update only those image components which are associated with changes in the earth model which affect the seismic imaging of the target; and

(d) replace image components in the seismic image with the updated image components to enhance the seismic image.