Simulating the Development of a Three-Dimensional Basinwide Overpressured Compartment
Basinwide overpressured compartments have been observed in the Anadarko and other basins. Results are presented on a mechano-chemical model of this phenomenon that illustrates how the imposed pattern of sedimentary features and faulting can produce such a three-dimensionally isolated compartment.
The model is based on the solution of equations describing pressure solution, stresses, conservation of pore fluid solutes, and the evolution of pore fluid pressure. The model accounts only for quartz chemistry; fluid over-pressuring is solely through thermal expansion of the fluid and compaction.
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Basins worldwide exhibit an unexpected degree of hydrologic segregation. There can be regions of a sedimentary basin that are isolated from their surroundings by a relatively thin envelope of low-permeability rock with an interior of sufficiently high permeability to maintain a consistent internal hydrostatic fluid pressure gradient. These have been named pressure compartments. Presure compartments have several remarkable features, just one of which is that internal fluid pressures can greatly exceed or be significantly less than any regional topographically controlled hydrologic head or drain. This publication contains 30 chapters that take detailed looks at pressure compartments in general, and detail case studies of these compartments in specific basins, such as the Anadarko and Gulf of Mexico. The volume also looks at other considerations in sedimentary basins such as hydrodynamic and thermal characteristics, and mechanical properties of rock.