Sandstone Consolidation Analysis to Delineate Areas of High Quality Reservoirs Suitable for Production of GeoPressured Geothermal Energy Along the Texas Gulf Coast




Loucks, R. G.
Dodge, M. M.
Galloway, William E.

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Analysis of reservoir quality of lower Tertiary sandstones along the Texas Gulf Coast delineatesareas most favorable for geopressured geothermal exploration. Reservoir quality is determined by whole core, acoustic log, and petrographic analyses.

Wilcox sandstones exhibit no regional reservoir quality trends. In the Lower and parts of the Middle and Upper Texas Gulf Coast, the sandstones are relatively well consolidated, but in other parts of the Middle and Upper Texas Gulf Coast, they show a reversal toward increased porosity at depth. Vicksburg sandstones have the poorest reservoir quality of sandstones of any formation prospective for geothermal energy. Frio sandstones show a systematic increase in reservoir quality from the Lower to the Upper Texas Gulf Coast. This increase in reservoir quality correlates to changes in rock composition and cementation. Acoustic log analysis substantiates a progression of greater consolidation from the Upper to the Lower Texas Gulf Coast.

Wilcox sandstones are poorly to moderately sorted, fine-grained, quartzose lithic arkoses, becoming more quartz-rich from the Upper to the Lower Texas Gulf Coast. Most rock fragments are metamorphic and volcanic. Vicksburg sandstones are poorly sorted, fine-grained lithic arkoses. Rock fragments are mainly volcanic clasts with lesser carbonate and minor metamorphic clasts. Frio sandstones range from poorly sorted, fine-grained, feldspathic litharenites to lithic arkoses in the Lower Texas Gulf Coast to poorly sorted, fine-grained, quartzose lithic arkoses to subarkoses in the Upper Texas Gulf Coast. Volcanic rock fragments predominate in all areas; carbonate rock fragments are common in the Lower Texas Gulf Coast.


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