Abstract: Modeling Fluid Flow Along Listric Growth Faults in the Eugene Island Block 330 Field, Gulf of Mexico

Dimas Coehlo, Laurel Alexander, Francois-Dominique Cipriani, and Lawrence Cathles, Sheila Roberts, Jeffrey Nunn

The giant Plio-Pleistocene Eugene Island Block 330 Field is thought to have been charged by hydrocarbons flowing up arcuate listric faults on the northern and eastern boundaries of the Eugene Island Block 330 mini-basin. Fluid migration in the mini-basin is modeled in two- and three-dimensions assuming fluid pathways are controlled mainly by stratigraphy and faults, and that the expulsion of fluids from overpressure is the primary driving force for fluid movement. The modeling is based on a finite element program called Akcess.Basin^TM Model fault zones are enclosed between parallel surfaces that displace sand and shale strata. The permeability of the sand layers caught between these fault surfaces are assigned in inverse proportion to their displacement/thickness ratio. Fau t permeability is also increased as fluid pressures approach and exceed a specified fraction of lithostatic, and in proportion to the rate of fault movement. In this way two and three dimensional flow models constructed from 4 north-south sections each with 17 sand layers and two major faults capture the essential geometry of the most important permeable units in the mini-basin. Akcess.Basin^TM finite element modeling then

shows how compaction and hydrocarbon generation drives flow through these units as the mini-basin grows. The models provide a quantitative picture of how and when pore fluids and hydrocarbons may have migrated in the South Eugene Island Block 330 mini-basin.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994