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