Determination of anisotropic physical characteristics in and around reservoirs

• US 20060153005A1
• Filed: 07/13/2005
• Published: 07/13/2006
• Est. Priority Date: 01/07/2005
• Status: Abandoned Application

• Current Assignee: WesternGeco LLC
• Original Assignee: WesternGeco LLC
• Inventors: Horne, Stephen Allan, Herwanger, Jorg V.
• Application Number:
  US11/180,956
• Publication Number:
  US 20060153005A1
• Time in Patent Office: Days
• US Class Current: 367/38
• CPC Class Codes: E21B 41/0064 Carbon dioxide sequestration storing fluids in porous layers B65G5/005
• CPC Class Codes: G01V 1/30 Analysis G01V1/50 takes precedence
• CPC Class Codes: G01V 2210/63 Seismic attributes, e.g. amplitude, polarity, instant phase
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A method and apparatus for use in estimating stress fields in a geological formation are disclosed. The method includes ascertaining a perturbation of stress in the triaxial stress state in a reservoir and in a surrounding rock mass over time; and determining the change in a seismic attribute resulting from the perturbation in the stress. The apparatus includes a program storage medium encoded with instructions that, when executed by a computing device, perform such a method or a computing system programmed to perform such a method.

Claims

1. A method, comprising:

ascertaining a perturbation of an anisotropic physical property in a reservoir and in a surrounding rock mass over time; and

determining the change in a seismic attribute resulting from the perturbation in the anisotropic physical property.

2. The method of claim 1, wherein ascertaining the perturbation of the anisotropic physical property includes ascertaining a perturbation in at least one of a multi-dimensional stress state, changes in fluid content, changes in fluid saturation, and dislocation of reflectors.

3. The method of claim 1, wherein ascertaining the perturbation of the anisotropic physical property includes:

modeling a reservoir and a rock mass surrounding the reservoir from acquired geophysical data; and

simulating the reservoir and rock mass over time from the reservoir and rock mass model.

4. The method of claim 3, wherein modeling the reservoir and the rock mass from acquired geophysical data includes building a coupled reservoir and geomechanical model.

5. The method of claim 3, wherein modeling the reservoir includes modeling at least one of a plurality of inclusions such as a plurality of pores and a plurality of fractures.

6. The method of claim 3, wherein modeling the reservoir and the rock mass from acquired geophysical data includes modeling the reservoir from a least one of seismic data, logging measurements, and core-measurement.

7. The method of claim 3, wherein modeling the reservoir and rock mass from acquired geophysical data includes modeling the reservoir from at least one of reservoir size, a count of the wells penetrating the reservoir, the locations of the wells penetrating the reservoir, the physical properties of the reservoir, and the initial stress state data.

8. The method of claim 3, wherein modeling the reservoir and the rock mass from acquired geophysical data includes specifying the mechanical properties of the reservoir and the rock mass.

9. The method of claim 3, wherein simulating the reservoir and rock mass over time includes simulating the reservoir during production over time.

10. A program storage medium encoded with instructions that, when executed by a computing device, perform a method comprising:

ascertaining a perturbation of an anisotropic physical property in a reservoir and in a surrounding rock mass over time; and

determining the change in a seismic attribute resulting from the perturbation in the stress.

11. The program storage medium of claim 10, wherein ascertaining the perturbation of the anisotropic physical property includes:

modeling a reservoir and a rock mass surrounding the reservoir from acquired geophysical data; and

simulating the reservoir and rock mass over time from the reservoir and rock mass model.

12. The program storage medium of claim 11, wherein modeling the reservoir and the rock mass from acquired geophysical data in the encoded method includes building a coupled reservoir and geomechanical model.

13. The program storage medium of claim 11, wherein modeling the reservoir in the encoded method includes modeling at least one of a plurality of inclusions such as a plurality of pores and a plurality of fractures.

14. The program storage medium of claim 11, wherein modeling the reservoir and the rock mass from acquired geophysical data in the encoded method includes modeling the reservoir from a least one of seismic data, logging measurements, and core-measurement.

15. The program storage medium of claim 11, wherein modeling the reservoir and rock mass from acquired geophysical data in the encoded method includes modeling the reservoir from at least one of reservoir size, a count of the wells penetrating the reservoir, the locations of the wells penetrating the reservoir, the physical properties of the reservoir, and the initial stress state data.

16. The program storage medium of claim 11, wherein modeling the reservoir and the rock mass from acquired geophysical data in the encoded method includes specifying the mechanical properties of the reservoir and the rock mass.

17. The program storage medium of claim 11, wherein simulating the reservoir and rock mass over time in the encoded method includes simulating the reservoir during production over time.

18. A computing apparatus comprising:

a processor;

a bus system;

a storage communicating with the processor over the bus system; and

a software application capable of performing, when invoked by the processor, a method comprising;

ascertaining a perturbation of an anisotropic physical property in a reservoir and in a surrounding rock mass over time; and

determining the change in a seismic attribute resulting from the perturbation in the stress.

19. The computing apparatus of claim 18, wherein ascertaining the perturbation of the anisotropic physical property includes:

modeling a reservoir and a rock mass surrounding the reservoir from acquired geophysical data; and

simulating the reservoir and rock mass over time from the reservoir and rock mass model.

20. The computing apparatus of claim 19, wherein modeling the reservoir and the rock mass from acquired geophysical data in the programmed method includes building a coupled reservoir and geomechanical model.

21. The computing apparatus of claim 19, wherein modeling the reservoir in the programmed method includes modeling at least one of a plurality of inclusions such as a plurality of pores and a plurality of fractures.

22. The computing apparatus of claim 19, wherein modeling the reservoir and the rock mass from acquired geophysical data in the programmed method includes modeling the reservoir from a least one of seismic data, logging measurements, and core-measurement.

23. The computing apparatus of claim 19, wherein modeling the reservoir and rock mass from acquired geophysical data in the programmed method includes modeling the reservoir from at least one of reservoir size, a count of the wells penetrating the reservoir, the locations of the wells penetrating the reservoir, the physical properties of the reservoir, and the initial stress state data.

24. The computing apparatus of claim 19, wherein modeling the reservoir and the rock mass from acquired geophysical data in the programmed method includes specifying the mechanical properties of the reservoir and the rock mass.

25. The computing apparatus of claim 19, wherein simulating the reservoir and rock mass over time in the programmed method includes simulating the reservoir during production over time.

26. A program storage medium encoded with a plurality of processed data generated by a method comprising:

ascertaining a perturbation of an anisotropic physical property in a reservoir and in a surrounding rock mass over time; and

determining the change in a seismic attribute resulting from the perturbation in the stress.

27. The program storage medium of claim 26, wherein ascertaining the perturbation of the anisotropic physical property includes:

modeling a reservoir and a rock mass surrounding the reservoir from acquired geophysical data; and

simulating the reservoir and rock mass over time from the reservoir and rock mass model.

28. The program storage medium of claim 27, wherein modeling the reservoir and the rock mass from acquired geophysical data in the encoded method includes building a coupled reservoir and geomechanical model.

29. The program storage medium of claim 27, wherein modeling the reservoir in the encoded method includes modeling at least one of a plurality of inclusions such as a plurality of pores and a plurality of fractures.

30. The program storage medium of claim 27, wherein modeling the reservoir and the rock mass from acquired geophysical data in the encoded method includes modeling the reservoir from a least one of seismic data, logging measurements, and core-measurement.

31. The program storage medium of claim 27, wherein modeling the reservoir and rock mass from acquired geophysical data in the encoded method includes modeling the reservoir from at least one of reservoir size, a count of the wells penetrating the reservoir, the locations of the wells penetrating the reservoir, the physical properties of the reservoir, and the initial stress state data.

32. The program storage medium of claim 27, wherein modeling the reservoir and the rock mass from acquired geophysical data in the encoded method includes specifying the mechanical properties of the reservoir and the rock mass.

33. The program storage medium of claim 27, wherein simulating the reservoir and rock mass over time in the encoded method includes simulating the reservoir during production over time.

34. A method, comprising:

creating a model of a reservoir and a surrounding rock mass from acquired geophysical data;

simulating the reservoir behavior during production from the model; and

applying the results of the simulation to a stress-sensitive rock physics model describing the changes in seismic velocities as a function of stress-state of a geologic formation defining the reservoir.

35. The method of claim 34, wherein modeling the reservoir from acquired geophysical data includes building a joint reservoir and geomechanical model.

36. The method of claim 34, wherein modeling the reservoir includes modeling at least one of a plurality of inclusions and a surrounding rock mass.

37. The method of claim 36, wherein modeling the plurality of inclusion includes modeling a plurality of pores or fractures.

38. The method of claim 34, wherein modeling the reservoir from acquired geophysical data includes modeling the reservoir from a least one of seismic data, logging measurements, and core-measurement.

39. The method of claim 34, wherein modeling the reservoir from acquired geophysical data includes modeling the reservoir from at least one of reservoir size, a count of the wells penetrating the reservoir, the locations of the wells penetrating the reservoir, the physical properties of the reservoir, and the initial stress state.

40. The method of claim 39, wherein modeling the reservoir from the physical properties of the reservoir includes modeling the reservoir from at least one of the fluid properties, the porosity of the material making up the reservoir, and the permeability of the material making up the reservoir, and the reservoir pore-pressure.

41. The method of claim 34, wherein modeling the reservoir from acquired geophysical data includes specifying the mechanical properties of a material comprising the reservoir and a surrounding rock mass.

42. The method of claim 41, wherein specifying the mechanical properties of the material comprising the reservoir and the surrounding rock mass includes specifying at least one of the Young'"'"'s modulus of the material and the Poisson'"'"'s ratio of the material wherein the material is an elastically deforming material.

43. The method of claim 41, wherein specifying the mechanical properties of the material comprising the reservoir and the surrounding rock mass further includes specifying material properties for non-elastic deformation.

44. The method of claim 34, wherein simulating the reservoir over time from the reservoir model includes producing reports of at least one physical property of the geological formation.

45. The method of claim 44, wherein producing reports of at least one physical property of the geological formation includes producing reports of the subsurface deformation and the tri-axial stress state at predetermined times of the simulation.

46. The method of claim 34, wherein applying the results of the simulation to the stress-sensitive rock physics model describing the changes in seismic velocities as a function of stress-state includes applying the results of the simulation to the stress-sensitive rock physics model describing the changes in seismic velocities as a function of a triaxial stress-state.

47. The method of claim 46, wherein applying the results of the simulation to the stress-sensitive rock physics model describing the changes in seismic velocities as a function of the triaxial stress-state includes applying the results of the simulation to a model determining anisotropic elastic properties due to closing of compliant fracture of pore space due to changes in effective stress.

48. A program storage medium encoded with instructions that, when executed by a computing device, perform a method comprising:

creating a model of a reservoir and a surrounding rock mass from acquired geophysical data;

simulating the reservoir behavior during production from the model; and

applying the results of the simulation to a stress-sensitive rock physics model describing the changes in seismic velocities as a function of stress-state of a geologic formation defining the reservoir.

49. The program storage medium of claim 48, wherein creating the model of the reservoir from acquired geophysical data in the encoded method includes building a joint reservoir and geomechanical model.

50. The program storage medium of claim 48, wherein modeling the reservoir from acquired geophysical data in the encoded method includes specifying the mechanical properties of a material comprising the reservoir and a surrounding rock mass.

51. The program storage medium of claim 48, wherein simulating the reservoir over time from the reservoir model in the encoded method includes producing reports of at least one physical property of the geological formation.

52. The program storage medium of claim 48, wherein applying the results of the simulation to the stress-sensitive rock physics model describing the changes in seismic velocities as a function of stress-state in the encoded method includes applying the results of the simulation to the stress-sensitive rock physics model describing the changes in seismic velocities as a function of a triaxial stress-state.

53. A computing apparatus comprising:

a processor;

a bus system;

a storage communicating with the processor over the bus system; and

a software application capable of performing, when invoked by the processor, a method comprising;

creating a model of a reservoir and a surrounding rock mass from acquired geophysical data;

simulating the reservoir behavior during production from the model; and

applying the results of the simulation to a stress-sensitive rock physics model describing the changes in seismic velocities as a function of stress-state of a geologic formation defining the reservoir.

54. The computing apparatus of claim 53, wherein creating the model of the reservoir from acquired geophysical data in the programmed method includes building a joint reservoir and geomechanical model.

55. The computing apparatus of claim 53, wherein modeling the reservoir from acquired geophysical data in the programmed method includes specifying the mechanical properties of a material comprising the reservoir and a surrounding rock mass.

56. The computing apparatus of claim 53, wherein simulating the reservoir over time from the reservoir model in the programmed method includes producing reports of at least one physical property of the geological formation.

57. The computing apparatus of claim 53, wherein applying the results of the simulation to the stress-sensitive rock physics model describing the changes in seismic velocities as a function of stress-state in the programmed method includes applying the results of the simulation to the stress-sensitive rock physics model describing the changes in seismic velocities as a function of a triaxial stress-state.

58. The computing apparatus of claim 53, further comprising the acquired geophysical data residing on the storage.

59. A program storage medium encoded with a plurality of processed data generated by a method comprising:

creating a model of a reservoir and a surrounding rock mass from acquired geophysical data;

simulating the reservoir behavior during production from the model; and

applying the results of the simulation to a stress-sensitive rock physics model describing the changes in seismic velocities as a function of stress-state of a geologic formation defining the reservoir.

60. The program storage medium of claim 59, wherein creating the model of the reservoir from acquired geophysical data in the encoded method includes building a joint reservoir and geomechanical model.

61. The program storage medium of claim 59, wherein modeling the reservoir from acquired geophysical data in the encoded method includes specifying the mechanical properties of a material comprising the reservoir and a surrounding rock mass.

62. The program storage medium of claim 59, wherein simulating the reservoir over time from the reservoir model in the encoded method includes producing reports of at least one physical property of the geological formation.

63. The program storage medium of claim 59, wherein applying the results of the simulation to the stress-sensitive rock physics model describing the changes in seismic velocities as a function of stress-state in the encoded method includes applying the results of the simulation to the stress-sensitive rock physics model describing the changes in seismic velocities as a function of a triaxial stress-state.

64. The computing apparatus of claim 59, further comprising the acquired geophysical data residing on the storage.

65. A method, comprising:

determine at least one anisotropic variation in a stress state of a reservoir and a surrounding rock mass over time; and

determine at least one anisotropic seismic attribute based on the anisotropic variation in the stress state of the reservoir and the surrounding rock mass.

66. The method of claim 65, further comprising modeling a future seismic response of the reservoir and the surrounding rock mass based on the anisotropic seismic attribute.

67. The method of claim 65, further comprising modeling geologic formations (e.g. subsidence) proximate to the reservoir and the surrounding rock mass based on the anisotropic seismic attribute.

68. A method, comprising:

ascertaining a perturbation of seismic velocities caused by changes in the stress state in a reservoir and in a surrounding rock mass over time; and

determining the change in a seismic attribute resulting from the perturbation in the anisotropic physical property.

69. The method of claim 68, wherein determining the perturbation in seismic velocities caused by changes in the stress state includes applying the changes of stress to a stress-sensitive rock physics model describing the changes in seismic velocities as a function of stress-state of a geologic formation defining the reservoir.

70. The method of claim 69, wherein applying the fluctuation of stress to the stress-sensitive rock physics model describing the changes in seismic velocities as a function of stress-state includes applying the results of the simulation to the stress-sensitive rock physics model describing the changes in seismic velocities as a function of a triaxial stress-state.