--> --> ABSTRACT: Comparison of Fault Sealing by Single and Multiple Layers of Shale: Outcrop Examples from the Gulf of Suez, Egypt, by Amgad I. Younes and Atilla Aydin; #90906(2001)
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Amgad I. Younes1, Atilla Aydin2

(1) Stanford University, Stanford, CA
(2) Stanford University

ABSTRACT: Comparison of Previous HitFaultNext Hit Sealing by Single and Multiple Layers of Shale: Outcrop Examples from the Gulf of Suez, Egypt

We examined the relationship between Previous HitfaultNext Hit offset, shale smear, and Previous HitfaultNext Hit seal potential along several reservoir-scale faults cutting a single, 50m thick layer of shale, and one 10 km -long Previous HitfaultNext Hit cutting 100m inter-bedded shales and sandstones. For single layers, the shale rotates until it parallels the Previous HitfaultNext Hit consistently thinning with Previous HitfaultNext Hit offset, regardless of the Previous HitfaultNext Hit size. Because Previous HitfaultNext Hit slip increases towards the center of the Previous HitfaultNext Hit, shale smear is thickest at Previous HitfaultNext Hit tips and thinnest near the Previous Hitfault'sNext Hit center, both in the strike and dip directions. Therefore, Previous HitfaultNext Hit centers are potentially riskier than Previous HitfaultNext Hit tips.

In contrast, multiple layers of incompetent rock causes a Previous HitfaultNext Hit to segment in the dip direction. Each segment has its local slip distribution and cuts a different stratigraphic section. Unless the segments have merged, the contribution of incompetent units to Previous HitfaultNext Hit sealing depends on the segment's offset to source shale thickness ratio (SSF) not an overall SSF. Competent rocks (sandstone or limestone) only boudinage forming discontinuous bodies. Consequently, a segmented Previous HitfaultNext Hit may leak at different locations depending on the local slip/shale thickness distribution.

In both single and multiple layers, however, the shale smear thickness approaches zero as Previous HitfaultNext Hit offset to source shale thickness reaches 4 - 6. But, multiple shale layers promote Previous HitfaultNext Hit segmentation eventually merging into a composite zone associated with a wider and taller Previous HitfaultNext Hit zone. It is essential to understand the 3D geometry of a Previous HitfaultNext Hit and the process of Previous HitfaultTop rock formation prior to assessing its seal potential.

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