--> Abstract: The Control of Provenance on Reservoir Quality and Rock Properties in the Gulf of Mexico, by Tobi H. Kosanke, Tom R. Taylor, Charlie D. Winker, Tim N. Diggs, and Neil R. Braunsdorf; #90039 (2005)

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The Control of Provenance on Reservoir Quality and Rock Properties in the Gulf of Mexico

Tobi H. Kosanke1, Tom R. Taylor2, Charlie D. Winker2, Tim N. Diggs2, and Neil R. Braunsdorf3
1 Shell International Exploration and Production Inc, New Orleans, LA
2 Shell International Exploration and Production Inc, Houston, TX
3 Shell International EP, Inc. - Technology Applications and Research, Houston, TX

Provenance exerts a significant influence on reservoir quality (RQ) by controlling the composition of sediments, which in turn impacts both mechanical properties and chemical diagenetic processes that decrease, preserve or increase porosity and permeability. We have compiled composition and textural data for the Gulf of Mexico (GOM) to determine the factors influencing provenance over time and its impact on RQ. Tectonic processes have controlled the location and magnitude of sediment delivery systems throughout the history of the GOM, leading to systematic changes in the provenance of sands in both space and time. Throughout the Cenozoic, sediment was consistently supplied from two distinct sources. The advance of the Laramide Front and subsequent Basin and Range tectonics altered the position of the sediment delivery systems in the Tertiary, resulting in a transitional change in sand composition through time concurrent with a lateral compositional trend from west-to-east. In the Plio-Pleistocene, deposition of quartz-rich sands gave way to less mature sands due to alteration of drainage patterns caused by ice sheet formation. The RQ of a sand of any particular age and location in the GOM will depend on its provenance. The most prevalent diagenetic effect in quartz-rich sandstones is porosity reduction by compaction and quartz cementation. Lithic-rich sands, however, experience reduction of permeability and porosity due to compaction of ductile grains and formation of carbonate cement, but less quartz cementation and greater secondary porosity; they may also exhibit grain coats that inhibit quartz cementation. By understanding and incorporating systematic mineralogic changes, we can improve pre-drill predictions of RQ in the GOM.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005