--> Abstract: Sequence-Based Reservoir Zonation and Controls on Distribution and Continuity of Reservoir at Fullerton Clearfork Field, Central Basin Platform, Permian Basin, West Texas, by J. C. Mitchell, H. W. Mueller, and M. T. Harris; #91012 (1992).

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ABSTRACT: Sequence-Based Reservoir Zonation and Controls on Distribution and Continuity of Reservoir at Fullerton Clearfork Field, Central Basin Platform, Permian Basin, West Texas

MITCHELL, JOHN C., and HARRY W. MUELLER, Exxon Production Research Company, Houston, TX, and MARK T. HARRIS, University of Wisconsin at Milwaukee, Milwaukee, WI

Sequence-based reservoir zonation of the Wichita and Lower Clearfork formations (Permian, Wolfcampian) at Fullerton Clearfork field better explains reservoir distribution and continuity than prior zonations. Integrated seismic, core, and wireline log data were used to establish this new zonation. Fourth-order sequences (parasequence sets) are the thinnest units correlatable field-wide, are thinner than layers previously used to subdivide the reservoir, and better match reservoir performance. The new correlations allow recognition of a major erosional surface (cross-cut by the old zonation) in the Wichita Formation. Productivity in the southeastern field area (below the erosional surface) is significantly better than in the northwestern field area (above the erosional surface).

Fourth-order parasequence sets stack predictably into third- and ultimately second-order sequences. Distribution of the best reservoir directly correlates with third-order (+/- million year) and second-order (+/- 5 million year) accommodation changes. The Wichita largely consists of thin, intertidal-capped parasequences deposited during a second-order sea level fall (limited accommodation). Intertidal and supratidal facies dominate individual parasequences and provide poor reservoir rock with thin, discontinuous porosity. In contrast, the Lower Clearfork largely consists of thick, shoal-capped parasequences deposited during a second-order sea level rise (increased accommodation). Component parasequences are thicker and consist of more laterally continuous porous and permeable reservoi zones dominated by dolomitized and undolomitized mud-lean packstone and grainstone shoal facies as well as dolomitized subtidal packstone. Thin, intertidal-capped parasequences occur only at tops of parasequence sets.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)