A gap exists in the oil and gas industry between exploration, and subsequent drilling and production. Geologic and geophysical data yield geometric and kinematic information rather than the stress and rock properties required by reservoir and production engineers. Numerical geomechanical modeling can bridge the gap by coupling physically realistic and mechanically rigorous analyses that yield testable predictions. Stratigraphic and structural data sets based on seismic and well data yield 3D geologic framework models (GFM). The GFM can be restored to an undeformed configuration that serve as templates for construction of geomechanical models. When coupled with realistic rock properties, this mechanically valid forward model can be used to validate the geometric and kinematic restoration. The complete stress, strain, and pore pressure distribution from the geomechanical model can be superimposed on realistic geometries. For drilling or reservoir performance applications, further simulations can address evolution of field-scale pore pressure and stress distributions during production. The models also provide context for focused well-bore scale simulations. These analyses offer detail comparable to measurements needed for reservoir simulations and can address issues such as well bore stability and formation damage. This integrated geomechanical approach provides complete description of deformations along with testable predictions of stress orientation and magnitude, fluid flow, rock properties, and sites of localized failure.
1. INTRODUCTION
In the oil and gas industry, a gap exists between the early phase of exploration, which is driven primarily by the fields of geology and geophysics, and the subsequent drilling and production phases where engineering plays the primary role. The gap is due in part to the large differences in scale that are inherent to the industry (basin versus field versus reservoir versus well bore). In addition, geologic and geophysical data yield primarily geometric and kinematic information, rather than the stress and rock properties that are required by reservoir and production engineers.
For example, the standard three-dimensional (3D) seismic data sets lead to stratigraphic and structural interpretations that are macroscale, geometric descriptions. These data and their interpretations contain explicit or implicit information on the temporal and spatial evolution of geologic structures (i.e., kinematics). Extensive small-scale data (e.g., pore pressure and in situ stress distributions) become available only after production drilling commences. Computational tools such as numerical geomechanical modeling offer an opportunity to bridge the gap by coupling physically realistic and mechanically rigorous numerical analyses with existing geometric and kinematic data to yield testable predictions. In this paper, we demonstrate how modern structural analysis can be coupled with geomechanical modeling to solve important problems in exploration and production that range from field scale stress and pore pressure prediction to borehole collapse and formation damage.
2. APPROACH
Our workflow incorporates traditional tools such as seismic interpretation and well data, if available, to generate stratigraphic and structural data sets that form the basis of a 3D geologic framework model (GFM). The GFM represents the present day state of knowledge for the problem of interest and serves as a starting point for further investigation.
