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Geomechanical Modeling of Stress and Strain Evolution in Fault-Related Folding

Smart, Kevin J.*1; Ferrill, David A.1; Morris, Alan P.1; McGinnis, Ronald N.1
(1) Southwest Research Inst, San Antonio, TX.

Understanding stress states and rock mass deformation deep underground is critical to a range of endeavors including oil and gas exploration and production, geothermal reservoir characterization and management, and subsurface disposal of CO2. Geomechanical modeling can predict the onset of failure, and the type and abundance of deformation features along with the orientations and magnitudes of stresses. This approach enables development of forward models that incorporate realistic mechanical stratigraphy (e.g., competence contrasts, bed thicknesses, bedding planes), include faults and bedding-slip surfaces as frictional sliding interfaces, reproduce the overall geometry of the structures of interest, and allow tracking of stress and strain through the deformation history. Use of inelastic constitutive relationships (e.g., elastic-plastic, viscoelastic) allows permanent strains to develop in response to the applied loads. This ability to capture permanent deformation is superior to linear elastic models, which are often used for numerical convenience but incapable of modeling permanent deformation or prediction of permanent deformation processes such as faulting, fracturing, and pore collapse. Finite element modeling results compared to field examples of natural fault-related folds show that well-designed geomechanical modeling can match overall fold geometries and be applied to stress, fracture, and subseismic fault prediction in geologic structures.


AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California