Improvements in reservoir modeling of compressional structures

Abstract

Techniques for incorporating faults in reservoir modeling systems have historically been developed first for extensional systems, and then extended to compressional systems. This approach has often led to reverse or thrust faults beings treated as special cases, requiring much manual editing of the model. The resulting 3D reservoir grids were often not acceptable to reservoir engineers due to the shape and orientation of the grid cells along the faults. The methodology that we have developed starts with the premise that no type of fault should need to be treated as a special case. The fault modeling can handle any shape fault, and the horizon modeling properly models repeat section. Reservoir grids created from these frameworks can treat faults as either pillar or stair‐step faults; stair‐step faults are often desired by the reservoir engineer to facilitate flow simulation. We have developed a new technique for indexing a 3D grid built with stair‐stepped reverse faults that preserves layer connectivity across the faults. In this manner, the grid that the engineer needs is also one that the geologist can use for facies and petrophysical modeling. The asset team is able to share the model without rebuilding or modifying the basic structure for each discipline, allowing the modeling to be part of a larger workflow.