Sedimentary basin deformation: an incremental stress approach
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A key component of sedimentary basin evolution is the spatial distribution and temporal variation of stress and deformation. The many deformation processes (poroelasticity, fracturing, irreversible nonlinear viscosity, and pressure solution) are inextricably bound in a tightly coupled network which, in turn, is coupled to a myriad of basin diagenetic, thermal and hydrologic processes. In the approach presented here, the various deformation processes are integrated through an incremental stress approach. Together with mass, momentum and energy conservation, this approach yields a complete, fully coupled basin model that captures basin and fault phenomena that are beyond the scope of simpler or decoupled models. Many of the most interesting basin phenomena are not only dependent on multiple, coupled processes but also are fundamentally three-dimensional. To address this three-dimensional complexity, we have developed a numerical simulator using a moving, adapting, accreting finite element grid which is allowed to deform and to grow and adapt with the addition of sediment to capture smaller sedimentary features. As a result, our fully coupled, comprehensive model allows one to solve a number of key problems in basin and fault dynamics. These include compaction, fractured reservoir and compartment genesis and dynamics. Examples illustrating these applications are presented for idealized systems and the Piceance Basin (Colorado) and the Permian Basin (West Texas). The incremental stress rheology is found to be a powerful formalism for integrating basin hydrology, diagenesis and mechanics.