Effective Geomechanical Modeling of Geologic Structures, 20-R9665

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Principal Investigators
Kevin J. Smart
David A. Ferrill
Alan P. Morris
Barron J. Bichon
David S. Riha
Luc Huyse (former SwRI employee)

Inclusive Dates:  10/01/06 – 04/01/08

Background - Although numerical modeling is a well-established tool in many scientific and engineering areas, the oil and gas industry has been hesitant to employ geomechanical modeling in the upstream phases of hydrocarbon prospect evaluation and reservoir characterization. A contributing factor to this reluctance is the short time scale for decision making compared to the typical time needed to build and analyze a representative geomechanical model. Furthermore, the uncertainties in boundary conditions and material properties often lead to poorly constrained problems that are difficult to validate against available field data.

Approach - The objectives were to develop an efficient workflow and set of best practices for effective numerical geomechanical modeling of hydrocarbon field- to reservoir-scale geologic structures by an analysis of a case example geologic structure. Big Brushy Canyon monocline in west Texas is an excellent analog for a common hydrocarbon reservoir structure in many Arabian Gulf oil fields and the study site provided sufficient exposure so that field observations and measurements could be compared to model predictions to validate the model. The fundamental project plan included:

  • field characterization to define the structural geometry and collect the data necessary for model validation
     
  • two-dimensional numerical modeling (both finite element and discrete element)
     
  • probabilistic analyses to assess the importance of parameters such as boundary conditions and material properties on numerical model predictions
     
  • three-dimensional numerical modeling that is conditioned by the best parameter estimates derived from the probabilistic modeling
     
  • development of an efficient but general workflow and a set of best practices.

Accomplishments - This project integrated field structural geology, finite element modeling and probabilistic analyses to develop an efficient workflow for effective numerical geomechanical modeling of geologic structures. Two-dimensional nonlinear finite element models were constructed to explore the structural development of the Big Brushy Canyon monocline, and field data were used to calibrate finite element model results. Insights gained during this project aided development of a generalized workflow for conducting efficient geomechanical modeling analyses for hydrocarbon exploration companies as well as other clients. The workflow and analyzed case example that resulted from this IR&D project represent a significant step forward in making numerical geomechanical modeling a more acceptable tool for analyzing complex problems in oil and gas exploration and production. Overall, this project demonstrated that integration of numerical modeling with sophisticated probabilistic analysis techniques is a powerful tool for understanding complex geomechanics problems.

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