Seismic constrained discrete fracture network

1. A method comprising:

receiving impedance values and azimuthal attribute values from an inversion based at least in part on seismic amplitude variation with azimuth data for a region of a geologic environment;

based at least in part on the impedance values and azimuthal attribute values, computing values that depend on components of a second-rank tensor;

selecting a fracture height for fractures in the geologic environment;

selecting an azimuth for a first fracture set of the fractures;

based at least in part on the values for the second-rank tensor, the selected fracture height and the selected azimuth, determining an azimuth for a second fracture set of the fractures;

generating a discrete fracture network for at least a portion of the region of the geologic environment wherein the discrete fracture network comprises fractures of the first fracture set and fractures of the second fracture set; and

based at least in part on the discrete fracture network, performing one or more of predicting permeability of a reservoir, determining a location for an in-fill well, determining an orientation of an in-fill well, and determining a location and an orientation of an in-fill well.

2. The method of claim 1 wherein the components of the second-rank tensor are associated with shear compliance.

3. The method of claim 1 wherein the components of the second-rank tensor comprise components with i, j indexes 1, 1, 1, 2 and 2, 2.

4. The method of claim 1 wherein the fractures are represented by fracture planes that are aligned substantially vertically and wherein the region of the geologic environment is characterized as being transversely isotropic with a vertical or tilted axis of rotational symmetry.

5. The method of claim 1 wherein the impedance values comprise S-Impedance values.

6. The method of claim 1 wherein the impedance values comprise P-Impedance values.

7. The method of claim 1 wherein the receiving comprises receiving impedance values for fast shear impedance I S1 and slow shear impedance I S2 .

8. The method of claim 1 wherein the receiving comprises receiving at least shear impedance values and a value for a fast shear azimuth.

9. The method of claim 1 wherein the inversion comprises a linearized orthotropic inversion.

10. The method of claim 1 wherein the receiving comprises receiving values for P-impedance (I P ), fast shear impedance (I S1 ), slow shear impedance (I S2 ) and fast shear azimuth ϕ S1 ).

11. The method of claim 1 comprising selecting fracture planes at random from probability distribution functions for determining agreement with results of seismic amplitude variation with azimuth inversion.

12. The method of claim 1 comprising selecting fracture planes for determining agreement with results of seismic inversion by using an appropriate scale-dependent relation between fracture normal and shear compliance and fracture dimensions.

13. The method of claim 1 wherein constraints from well data constrain fracture orientations at one or more well locations and at least in part determine properties of background media.

14. The method of claim 1 comprising computing values that depend on components of the second-rank tensor and that depend on components of a fourth- rank tensor wherein the components of the second-rank tensor are associated with shear compliance and wherein the components of the fourth-rank tensor are associated with normal compliance and shear compliance.

15. A system comprising:

a processor;

memory operatively coupled to the processor; and

one or more modules that comprise processor-executable instructions stored in the memory to instruct the system wherein the instructions comprise instructions to:

receive impedance values and azimuthal attribute values from an inversion based at least in part on seismic amplitude variation with azimuth data for a region of a geologic environment;

based at least in part on the impedance values and azimuthal attribute values, compute values that depend on components of a second-rank tensor;

select a fracture height for fractures in the geologic environment;

select an azimuth for a first fracture set of the fractures;

based at least in part on the values for the second-rank tensor, the selected fracture height and the selected azimuth, determine an azimuth for a second fracture set of the fractures;

generate a discrete fracture network for at least a portion of the region of the geologic environment wherein the discrete fracture network comprises fractures of the first fracture set and fractures of the second fracture set; and

based at least in part on the discrete fracture network, perform one or more of predict permeability of a reservoir, determine a location for an in-fill well, determine an orientation of an in-fill well, and determine a location and an orientation of an in-fill well.

16. A method comprising:

receiving impedance values and azimuthal attribute values from an inversion based at least in part on seismic amplitude variation with azimuth data for a region of a geologic environment;

based at least in part on the impedance values and azimuthal attribute values, computing values that depend on components of a second-rank tensor;

selecting a fracture height for fractures in the geologic environment;

selecting an azimuth for a first fracture set of the fractures;

based at least in part on the values for the second-rank tensor, the selected fracture height and the selected azimuth, determining an azimuth for a second fracture set of the fractures;

generating a discrete fracture network for at least a portion of the region of the geologic environment wherein the discrete fracture network comprises fractures of the first fracture set and fractures of the second fracture set; and

selecting fracture planes for determining agreement with results of seismic inversion by using an appropriate scale-dependent relation between fracture normal and shear compliance and fracture dimensions.

17. The method of claim 16 wherein the components of the second-rank tensor are associated with shear compliance.

18. The method of claim 16 wherein the receiving comprises receiving impedance values for fast shear impedance I si and slow shear impedance I S2 .

19. The method of claim 16 wherein the receiving comprises receiving at least shear impedance values and a value for a fast shear azimuth.

20. The method of claim 16 comprising computing values that depend on components of the second-rank tensor and that depend on components of a fourth-rank tensor wherein the components of the second-rank tensor are associated with shear compliance and wherein the components of the fourth-rank tensor are associated with normal compliance and shear compliance.