Systems and methods for modeling faults in the subsurface
View Patent ↗A method, apparatus and system for modeling a fault surface in a subsurface region. A direction may be determined in which a first portion of the subsurface region being on one side of the fault surface has moved relative to a second portion of the subsurface region being on the other side of the fault surface. A model of the fault surface may be generated having substantially no protrusions in the determined direction. A visualization of the model of the generated fault surface may be displayed.
1. A method for modeling a plurality of fault surfaces that are substantially parallel to each other using measured data collected from subsurface regions of the Earth, the method comprising:
receiving a plurality of sets of sampling points, generated from the measured data, each set of sampling points corresponding to a different one of the plurality of fault surfaces;
generating a three-dimensional scalar field representing the values of sampling points from each of the plurality of sets;
associating each of a plurality of scalar field values in the three-dimensional scalar field with a single one of the plurality of fault surfaces to generate a plurality of level set fault surfaces;
simultaneously generating a model of the plurality of fault surfaces by applying a continuous operation throughout the three-dimensional scalar field; and
displaying the plurality of fault surfaces together in the subsurface modeled domain.
2. The method of claim 1 , wherein the plurality of fault surfaces are modeled in a sub-region of the entire modeled domain, wherein the sub-region is a portion of the modeled domain in which the faults are substantially parallel to each other.
3. The method of claim 1 , comprising, if the plurality of fault surfaces are substantially parallel in only a first sub-region of the modeled domain and intersect in a second sub-region of the modeled domain, modeling the plurality of fault surfaces in the first sub-region simultaneously and modeling fault surfaces in the second sub-region individually.
4. The method of claim 3 comprising merging the fault surfaces modeled in the first sub-region and the second sub-region at a boundary of the two regions.
5. The method of claim 1 , wherein the model is generated so that the plurality of fault surfaces do not cross.
6. The method of claim 1 , comprising:
selecting a fault surface from the plurality of fault surfaces and associating the fault surface with a level set value; and
for each sampling point in the set of sampling points corresponding to the selected fault surface, setting the value of the three-dimensional scalar field at the sampling point to be equal to the level set value.
7. The method of claim 6 , comprising, for each fault surface in the plurality of fault surfaces, setting the average gradient of the three-dimensional scalar field to be equal to the average normal computed from the set of sampling points.
8. The method of claim 6 , comprising, for each fault surface in the plurality of fault surfaces other than the selected fault surface:
arrange the corresponding set of sampling points in an ordered sequence;
pair each of a plurality of sampling points in the sequence with a subsequent sampling point in the sequence; and
set the difference between the value of the three-dimensional scalar field at the sampling points in each pair of sampling points to zero.
9. The method of claim 6 , comprising, for each fault surface in the plurality of fault surfaces other than the selected fault surface:
select a reference point in the corresponding set of sampling points; and
set the difference between the value of the three-dimensional scalar field at the reference point and each of the sampling points in the corresponding set of sampling points to zero.
10. The method of claim 6 , comprising, for each sampling point in the set of sampling points corresponding to each fault surface, setting the gradient of the three-dimensional scalar field at the sampling point to be orthogonal to a vector field of throw vectors tangent to the fault surface.
11. The method of claim 1 , comprising:
covering the subsurface modeled domain by a mesh comprising nodes; and
generating the three-dimensional scalar field using values sampled at the nodes of the mesh.
12. The method of claim 11 , comprising, for a point of the model that is not a node of the mesh, locally approximating the value of the three-dimensional scalar field at the point from the value of the three-dimensional scalar field at a node of the mesh neighboring the point.
13. The method of claim 12 , comprising locally approximating the value of the three-dimensional scalar field at the point that is not a node as a linear approximation of the value of the three-dimensional scalar field at the neighboring node of the mesh.
14. The method of claim 1 , wherein the plurality of sets of sampling points is geological data produced in a three dimensional field by a seismic transmitter emitting seismic waves that reflect at geological discontinuities throughout the subsurface structure and a receiver receiving the reflected seismic waves that correspond to the seismic waves output by transmitter.
15. The method of claim 14 , wherein said geological data is seismic data produced in a three-dimensional field by an air gun or explosives.
16. A system for modeling a plurality of fault surfaces that are substantially parallel to each other using measured data collected from subsurface regions of the Earth, the system comprising:
one or more processors configured to:
receive a plurality of sets of sampling points, generated from the measured data, each set of sampling points corresponding to a different one of the plurality of fault surfaces,
generate a three-dimensional scalar field representing the values of sampling points from each of the plurality of sets,
associate each of a plurality of scalar field values in the three-dimensional scalar field with a single one of the plurality of fault surfaces to generate a plurality of level set fault surfaces,
simultaneously generate a model of the plurality of fault surfaces by applying a continuous operation throughout the three-dimensional scalar field; and
a display configured to display the plurality of fault surfaces together in the subsurface modeled domain.
17. The system of claim 16 , wherein the one or more processors are configured to model the plurality of fault surfaces in a sub-region of the entire modeled domain, wherein the sub-region is a portion of the modeled domain in which the faults are substantially parallel to each other.
18. The system of claim 16 , wherein, if the plurality of fault surfaces are substantially parallel in only a first sub-region of the modeled domain and intersect in a second sub-region of the modeled domain, the one or more processors are configured to model the plurality of fault surfaces in the first sub-region simultaneously and modeling fault surfaces in the second sub-region individually.
19. The system of claim 18 , wherein the one or more processors are configured to merge the fault surfaces modeled in the first sub-region and the second sub-region at a boundary of the two regions.
20. The system of claim 16 , wherein the one or more processors are configured to generate the model so that the plurality of fault surfaces do not cross.