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

• US 7,480,206 B2
• Filed: 09/13/2004
• Issued: 01/20/2009
• 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
• Primary Examiner(s): Keith; Jack W.
• Assistant Examiner(s): Hughes; Scott A
• Application Number:
  US10/940,579
• Publication Number:
  US 20060056272A1
• Time in Patent Office: 1,590 Days
• Field of Search: 367 72- 73, 367 37- 38, 367/61, 367 50- 52, 702/16, 702/18
• 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 depth-migrated seismic image, the method comprising:

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

b) transforming the seismic data into a set of energy components;

c) creating an earth model having velocity model characterizations therewithin representative of the subterranean region, the earth model comprising a set of lens elements having propagation properties which affect energy propagation through the lens elements;

d) propagating the set of energy components through the lens elements to form image components which are combined into a depth-migrated seismic image;

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

f) selecting a trial subset of less than all of the lens elements from the set of lens elements and updating propagation properties of the trial subset of lens elements which may affect imaging of the target without updating the propagation properties of all of the lens elements of the earth model;

g) selecting a trial subset of less than all of the energy components from the set of energy components which may affect imaging of the target;

h) propagating the trial subset, without propagating all, of the set of energy components through the earth model to form updated image components; and

1) updating the seismic image by replacing image components of the current seismic image with the updated image components without replacing all of the image components to arrive at an enhanced seismic image.

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.

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 subset of lens elements is 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 subset of lens elements is selected by visual inspection.

10. The method of claim 1 wherein:

the trial subset of energy components is selected using a directed-aperture.

11. The method of claim 1 wherein:

the trial subset of energy components is selected using a migration aperture.

12. The method of claim 1 wherein:

the trial subset of energy components is selected using ray tracing.

13. The method of claim 1 wherein:

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

17. The method of claim 16 wherein:

the trial subset of energy components is selected from the 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. The method of claim 1 wherein:

steps (e)-(i) are repeated at least one more time.

20. The method of claim 1 wherein:

the earth model is a velocity model.

21. The method of claim 1 wherein step (d) further comprises:

generating the depth-migrated seismic image with depth migration software.

22. The method of claim 1 wherein step (d) further comprises:

generating the depth-migrated seismic image with depth-migration imaging software responsive to the earth model having velocity model characterizations therewithin.

23. The method of claim 20 wherein step (d) further comprises:

generating the depth-migrated seismic image with depth-migration imaging software responsive to the velocity model.

4. The method of claim I wherein:

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

24. A method for enhancing a depth-migrated seismic image comprising:

a) propagating a set of seismic energy components through an earth model having velocity model characterizations therewithin comprising a set of lens elements to form a set of image components which are summed to form a depth-migrated seismic image;

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

c) updating a trial subset of lens elements of less than all of the lens elements from the set of lens elements to update the earth model without updating all of the lens elements of the earth model;

d) selecting a trial subset of energy components of less than all of the energy components from the energy components of step (a);

e) propagating the trial subset of energy components through the updated earth model without propagating all of the set of energy components through the updated earth model to create updated image components; and

f) replacing current image components with the updated image components and not replacing those image components that were not updated to create an enhanced seismic image.

25. The method of claim 24 wherein:

the energy components are beam components.

26. A method for enhancing a depth-migrated seismic image comprising:

a) creating a depth-migrated seismic image using an earth model having velocity model characterizations therewithin comprising a set of lens elements and using seismic data, the seismic image comprising a set of image components, the seismic image including a target which is to be enhanced;

b) updating a trial subset of less than all of the lens elements selected from the set of lens elements in the earth model;

c) updating those image components in the seismic image which are associated with changes in the trial subset of lens elements of the earth model which affect the seismic imaging of the target; and

d) subtracting image components in the seismic image and adding in their place updated image components without replacing all of the image components to enhance the seismic image.

27. A method for enhancing a depth-migrated seismic image comprising:

a) propagating a set of seismic energy components through a velocity model, comprising a set of lens elements, to form a set of image components which are summed to form an original depth-migrated seismic image;

b) updating at least some of the lens elements to update the velocity model;

c) selecting a trial subset of energy components of less than all of the energy components from the set of energy components of step (a);

d) propagating the trial subset, without propagating all, of the energy components through the updated velocity model to create updated image components; and

e) subtracting image components from the original seismic image and adding in their place updated image components, without replacing all of the image components of the original seismic image, to arrive at an updated enhanced seismic image.

28. The method of claim 27 wherein:

less than of the all of the lens elements are updated in step b) to update the velocity model.

29. The method of claim 27 wherein:

the trial subset of lens elements is selected by visual inspection.

30. The method of claim 27 wherein:

the trial subset of energy components is selected using a directed-aperture.

31. The method of claim 27 wherein:

the trial subset of energy components is selected using a migration aperture.

32. The method of claim 27 wherein:

the updated image components of the enhanced seismic image replace corresponding image components from the original seismic image and image components for which no updated image components were created in step d) remain the same between the updated seismic image and the original seismic image.

33. The method of claim 27 wherein:

a target is selected in the current original seismic image which is to be enhanced.

34. The method of claim 33 wherein:

the step of selecting a trial subset of energy components of less than all of the energy components uses ray tracing to select energy components which may affect imaging of the target.

35. The method of claim 34 wherein:

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

36. The method of claim 34 wherein:

the ray tracing utilizes normal ray tracing.

37. The method of claim 34 wherein:

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

38. The method of claim 34 wherein:

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

39. The method of claim 34 wherein:

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

40. The method of claim 34 wherein:

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