--> Abstract: Effects Of Sedimentation, Salt Deformation, And Fault Propagation In Southern Walker Ridge To Northern Ewing Bank, Gulf Of Mexico: Implications For Cenozoic Fluid Flow Patterns And Overpressure Development, by S. C. Stover, P. Weimer, S. Ge, and B. C. Mcbride; #90928 (1999).

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Abstract: Effects of sedimentation, salt deformation, and fault propagation in southern Walker Ridge to northern Ewing Bank, Gulf of Mexico: Implications for Cenozoic fluid flow patterns and overpressure development

STOVER, S. CHEREE1, PAUL WEIMER1, SHEMIN GE1, and BARRY C. MCBRIDE2
1Department of Geological Sciences, University of Colorado, Boulder, CO
2HS Resources, 1999 Broadway, Suite 3600, Denver, CO

Fluid-flow modeling of a sequentially restored cross section across the northern Gulf of Mexico Basin explores a unique avenue in which to study the effects of basin heterogeneities on three-phase fluid migration during the Cenozoic. The cross section is 600 km long, extending from northern Louisiana to south of the Sigsbee Escarpment. Structural reconstructions include 66.4, 40.0, 21.5, 15.5, 10.5, 8.8, 5.5, 3.0, 1.1 Ma and Present. These restorations indicate a complex evolution of fault growth, sedimentation, and multi-level allochthonous salt deformation, all of which profoundly influenced the migration of oil, gas, and water. However, the historic fluid flow patterns and basin heterogeneity influence remain poorly understood. To enhance understanding of these components, we have modeled the fluid flow patterns for the ten restorations using a coupled numerical model.

Our modeling indicates that excess pressure gradients and lithologic parameters appear to be the primary factors governing regional fluid flow direction and velocity. However, the development of localized high permeability zones coincident with the growth of salt stocks, as observed in the 66.4-8.8 Ma restorations, enforces migration along the sides of the stocks. Furthermore, modeled profiles of permeability and porosity underlying salt canopies, as seen in the South Timbalier salt sheet from 12.5-10.5 Ma and in southern Green Canyon from 5.5-1.1 Ma, suggest a low-magnitude gumbo zone that intermittently serves as a fluid migration pathway. The development of faults in the detachment province south of South Pelto and within Ewing Bank also appear to govern local flow fields, with the fluid flow occurring primarily along the larger faults, and a lower magnitude of flow along adjacent, smaller faults.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas