Distribution and Nature of Fault Architecture in a Layered Sandstone and Shale Sequence: An Example from the Moab Fault, Utah
N. C. Davatzes, A. Aydin, 2005. "Distribution and Nature of Fault Architecture in a Layered Sandstone and Shale Sequence: An Example from the Moab Fault, Utah", Faults, Fluid Flow, and Petroleum Traps, Rasoul Sorkhabi, Yoshihiro Tsuji
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We examined the distribution of fault rock and damage zone structures in sandstone and shale along the Moab fault, a basin-scale normal fault with nearly 1 km (0.62 mi) of throw, in southeast Utah. We find that fault rock and damage zone structures vary along strike and dip. Variations are related to changes in fault geometry, faulted slip, lithology, and the mechanism of faulting. In sandstone, we differentiated two structural assemblages: (1) deformation bands, zones of deformation bands, and polished slip surfaces and (2) joints, sheared joints, and breccia. These structural assemblages result from the deformation band-based mechanism and the joint-based mechanism, respectively. Along the Moab fault, where both types of structures are present, joint-based deformation is always younger. Where shale is juxtaposed against the fault, a third faulting mechanism, smearing of shale by ductile deformation and associated shale fault rocks, occurs. Based on the knowledge of these three mechanisms, we projected the distribution of their structural products in three dimensions along idealized fault surfaces and evaluated the potential effect on fluid and hydrocarbon flow. We contend that these mechanisms could be used to facilitate predictions of fault and damage zone structures and their permeability from limited data sets.
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Japan National Oil Corporation (JNOC) (presently Japan Oil, Gas and Metals National Corporation) launched a multidisciplinary and international project on the Evaluation of Traps and Seals in 1997. The project ended in 2003. This publication resulted from that project and includes JNOC research articles as well as contributions from industry and academia. The 17 papers in this volume cover topics such as a method to estimate the amount of oil/gas accumulation using the concept of equivalent grain size in seal rock, and oil/gas migration to and spill-point geometry of petroleum traps; two case studies of fault seal assessment applied to normal faults in Tertiary clastic reservoirs in offshore Sarawak and offshore Gulf of Thailand; and physical analog studies of the development of extensional faults. This publication also contains a valuable bibliography of nearly 1000 additional articles and books published on fault traps, fault seal processes, and fault-related fluid flow in sedimentary basins, for use as a reference tool to delve into publications preceding this volume.