Systems, methods, and apparatus for discrete fracture simulation of complex subsurface fracture geometries

1. A method for simulating a subterranean region having fracture geometries, comprising:

obtaining data produced by a simulator module, the data representing the subterranean region and comprising matrix grid data and parameters associated with fractures in the subterranean region;

in a computational domain separate from the simulator module, using the obtained data produced by the simulator module to produce a matrix grid by:

identifying geometric interactions between fractures and matrix cells in the matrix grid;

creating a new fracture cell for each segment of a fracture interacting with a matrix cell in the matrix grid;

creating at least one null cell in the matrix grid to maintain the same number of cells in a row or column of the matrix grid as needed;

cancelling at least one grid cell connection from the obtained data produced by the simulator module;

assigning physical properties to each new created fracture cell;

identifying geometric relationships between the new created fracture cells and between the new created fracture cells and the matrix cells; and

calculating fluid flow transmissibility factors between the new created fracture cells and between the new created fracture cells and the matrix cells;

inputting the calculated fluid flow transmissibility factors into the simulator module;

generating a simulation of the subterranean region with the simulator module using the calculated fluid flow transmissibility factors.

2. The method of claim 1 , wherein the identifying geometric relationships between the new created fracture cells and between the new created fracture cells and the matrix cells comprises identifying non-neighboring connections.

3. The method of claim 2 , wherein the identifying geometric interactions, creating new fracture cells, creating at least one null cell, cancelling at least one grid cell connection, assigning physical properties to the new fracture cells, identifying geometric relationships, and calculating fluid flow transmissibility factors is all performed via a preprocessor configured to generate corresponding output values.

4. The method of claim 3 , wherein the output values generated by the preprocessor are input into the simulator module to generate the simulation of the subterranean region.

5. The method of claim 1 , wherein the identifying geometric relationships between the new created fracture cells comprises identifying connections between the new created fracture cells corresponding to the same fracture.

6. The method of claim 1 , wherein the identifying geometric relationships between the new created fracture cells comprises identifying connections between the new created fracture cells corresponding to different fractures.

7. The method of claim 1 , wherein producing the matrix grid further comprises discretizing nonplanar fractures into multiple interconnected planar fracture segments.

8. The method of claim 1 , wherein:

the obtained data produced by the simulator module includes well parameters;

producing the matrix grid further comprises calculating a well index between the new created fracture cells and wellbore cells associated to the well parameters;

and the generating the simulation of the subterranean region includes using the calculated well index.

9. The method of claim 8 , wherein producing the matrix grid further comprises:

identifying geometric interactions between fractures and the wellbore cells;

and adding a well location to the new created fracture cells for each segment of a fracture interacting with a wellbore cell.

10. The method of claim 1 , wherein the generating a simulation of the subterranean region comprises generation of a geometry including at least one of: (i) a complex boundary, (ii) a complex surface, or (iii) a corner point.

11. A system for simulating a subterranean region having fracture geometries, comprising:

at least one processor;

a memory linked to the processor, the memory having instructions stored therein, which when executed by the processor cause the processor to perform functions including to:

input data produced by a simulator module, the data representing the subterranean region and comprising matrix grid data and parameters associated with fractures in the subterranean region;

produce a matrix grid using the input data to:

identify geometric interactions between fractures and matrix cells in the matrix grid;

create a new fracture cell for each segment of a fracture interacting with a matrix cell in the matrix grid;

create at least one null cell in the matrix grid to maintain the same number of cells in a row or column of the matrix grid as needed;

cancel at least one grid cell connection from the input data produced by the simulator module;

assign physical properties to each new created fracture cell;

identify geometric relationships between the new created fracture cells and between the new created fracture cells and the matrix cells;

calculate fluid flow transmissibility factors between the new created fracture cells and between the new created fracture cells and the matrix cells;

input the calculated fluid flow transmissibility factors into the simulator module; and

generate a simulation of the subterranean region with the simulator module using the calculated fluid flow transmissibility factors.

12. The system of claim 11 , wherein the function to identify geometric relationships between the new created fracture cells and between the new created fracture cells and the matrix cells comprises identification of non-neighboring connections.

13. The system of claim 12 , wherein the functions performed by the processor further include functions to produce output values corresponding to the identified geometric interactions, the new created fracture cells, each at least one created null cell, the assigned physical properties, the identified geometric relationships, and the calculated fluid flow transmissibility factors.

14. The system of claim 13 , wherein the functions performed by the processor further include functions to input the produced output values into the simulator module to generate the simulation of the subterranean region.

15. The system of claim 11 , wherein the function to identify geometric relationships between the new created fracture cells comprises identification of connections between the new created fracture cells corresponding to the same fracture.

16. The system of claim 11 , wherein the function to identify geometric relationships between the new created fracture cells comprises identification of connections between the new created fracture cells corresponding to different fractures.

17. The system of claim 11 , wherein the function to produce a matrix grid further includes functions to discretize nonplanar fractures into multiple interconnected planar fracture segments.

18. The system of claim 11 , wherein the function to produce the matrix grid further includes functions to:

input data produced by the simulator module including well parameters;

calculate a well index between the new created fracture cells and wellbore cells associated to the well parameters; and

the function to generate a simulation of the subterranean region includes a function to use the calculated well index to generate the simulation.

19. The system of claim 18 , wherein the function to produce the matrix grid further includes functions to:

identify geometric interactions between fractures and the wellbore cells; and

add a well location to the new created fracture cells for each segment of a fracture interacting with a wellbore cell.

20. The system of claim 11 , wherein the function to produce the matrix grid further includes functions to:

discretize fractures with variable apertures into connecting segments; and

assign each segment an average aperture value and a permeability value.

21. The system of claim 11 , wherein the function to generate a simulation of the subterranean region comprises generation of a geometry including at least one of: (i) a complex boundary, (ii) a complex surface, or (iii) a corner point.