Fluid flow and sediment deformation in the evolution of sedimentary basins: One-dimensional application to Woodlark Basin, Papua New Guinea and two-dimensional application to the northern Gulf of Mexico Basin

The coupling of hydrological and mechanical processes during the evolution of sedimentary basins can be influenced by varying degrees of sediment loading, faulting, and complex stratigraphic and structural deformation. One-dimensional analytically-based numerical modeling and experimental testing of shallow marine sediment cores gives insight into the mechanisms governing compaction during the past six my in the tectonically-active Woodlark Basin, Papua New Guinea. Basin-scale two-dimensional numerical modeling in the Northern Gulf of Mexico Basin illustrates the pressure and thermal regimes that develop over a 66.4 my time period, and their influence on petroleum systems.; An analytically-based numerical modeling framework was constructed to address both poroelastic consolidation and viscous consolidation through pressure solution during sedimentary basin evolution. Generic studies suggest that application of fully poroelastic processes will overestimate sediment porosities at depths approaching and exceeding one kilometer, while use of fully viscous deformation processes will overestimate sediment porosities at shallow burial depths. Permeability and porosity measurements on sediment cores collected from a 746-meter deep borehole at Woodlark Basin reveal a porosity profile that deviates from an exponential decrease with depth, and vertical permeabilities ranging between 10−16 to 10−18 m 2. Application of these data and the model to Woodlark Basin shows that lithologic strength, and not overpressure development, controlled the compaction history. Moreover, simulations indicate that although poroelastic deformation has been the dominant mode of compaction at Woodlark Basin, viscous deformation may have played a role in porosity reduction at burial depths exceeding 590 meters.; A two-dimensional numerical model to address transient heat and multi-phase fluid flow was customized and applied to a 600 kilometer restored cross-section in the northern Gulf of Mexico Basin. Discrete basin-scale models were constructed for the time period of 66.4 Ma to present day and were sequentially forward modeled. The simulations reveal that the presence of allochthonous salt retarded source rock maturation, while overpressure development had a minor impact on oil generation. Excess pressure gradients and lithology anisotropy governed oil migration patterns, with lateral dissemination dominating the flow patterns and buoyancy-driven vertical flow becoming more significant as pressures approach hydrostatic and in more isotropic lithologies. Low permeability salt structures enforced lateral flow patterns, and upon salt evacuation, source rock maturation accelerated, and oil migrated was driven across welds when overpressures exceeded 50 MPa. Fault-dominated flow patterns developed upon fault penetration of high excess pressure regimes, with episodic along-fault migration dominating the patterns in the central regions of the cross-section.