Joel S. Watkins¹, Carrie L. Decker¹, Roger Sassen¹, T. A. Blasingame¹, Yuqian Li¹, Jianyong Bai¹, Ron Gan¹

(1) Texas A&M University, College Station, TX

ABSTRACT: Low-Throw, Near-Vertical Faults (LTNVF): Their Role in Migration, Entrapment and Production

Low-throw, near-vertical faults (LTNVF) are defined as faults with throws at or near the level of seismic detection on modern data. In the northern Gulf of Mexico and Gulf Coast, LTNVF are found around salt structures, as secondary or tertiary faults associated with large growth faults, as transfer faults accommodating differential movement within large fault blocks, and as compaction faults. Low-throw generally results in low capillary displacement pressures within the fault gouge. Intersecting LTNVF may form compartments. Many are unrecognized or ignored during seismic mapping.

Computer simulations and field studies in Ship Shoal 274, Main Pass 259 and a south Texas field show that these faults are abundant, form barriers to hydrocarbon flow, albeit often leaky. In SS 274, production data suggests that approximately half of the fault-bounded compartments are leaky. Reservoirs almost a mile apart in a South Texas field are in communication. Computer simulations show that LTNVF can cause geochemical fractionation during charge, reduce recoverable hydrocarbons and, surprisingly, slightly increase total recovery under certain conditions during water flooding.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado