--> ABSTRACT: Reservoir Geology and Paleoenvironmental Reconstruction of Yates Formation, Central Basin Platform, West Texas, by R. R. Casavant; #91030 (2010)

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Reservoir Geology and Paleoenvironmental Reconstruction of Yates Formation, Central Basin Platform, West Texas

R. R. Casavant

Computer slice maps and proprietary three-dimensional interactive graphics were used to reconstruct the paleodeposition and to map reservoir variations within the Yates Formation of west Texas. The prolific Yates Formation is a major reservoir in the North Ward Estes field, Ward County, Texas.

The Upper Permian (Guadalupian) Yates Formation is an overall regressive, shallowing-upward package containing variable sequences of subtidal, intertidal, and supratidal strata. Sediment types include various siliciclastics mixed with sabkha-type carbonates and evaporites. The types of rocks and their structures indicate that these sediments were deposited in a prograding tidal flat-lagoonal setting located behind a shelf margin edge on the western flank of the positive Central Basin platform during the Guadalupian. The cyclic nature of the Yates is largely the result of lagoonal expansion and construction that caused environmental belts on both sides of the lagoon to converge and diverge. These rapid migrations of facies coupled with diagenetic processes created the heterogeneities t at characterize this large reservoir.

The reservoir rocks in the Yates Formation range from siltstones to fine-grained sandstones and contain various amounts of cement and clay matrix. These constituents and their distribution vary significantly throughout the reservoir. A better understanding of their distribution and influences on reservoir performance, as well as prediction in other less developed areas, was achieved from analysis of the paleoenvironmental maps.

Like many of the large Permian oil fields located on the Central Basin platform, the North Ward Estes field drapes over a narrow north-south-trending anticlinal structure along most of its length, adding a structural component to development strategies.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.