An Integrated, Multidisciplinary Study of Reservoir Facies and Reservoir Performance of a Multilayer, No-Crossflow Gas Reservoir—Chase Group (Wolfcampian), Guymon-Hugoton Field, Oklahoma
M. J. Fetkovich, W. T. Siemers, J. J. Voelker, J. S. Williams, A. M. Works, D. J. Ebbs, 1991. "An Integrated, Multidisciplinary Study of Reservoir Facies and Reservoir Performance of a Multilayer, No-Crossflow Gas Reservoir—Chase Group (Wolfcampian), Guymon-Hugoton Field, Oklahoma", The Integration of Geology, Geophysics, Petrophysics and Petroleum Engineering in Reservoir Delineation, Description and Management, Robert Sneider, Wulf Massell, Rob Mathis, Dennis Loren, Paul Wichmann
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This paper summarizes a comprehensive study of the depositional, diagenetic, petrophysical, and production characteristics of the Chase Group (Wolfcampian) gas reservoirs, Guymon-Hugoton Field, Oklahoma. Integration of disciplines in geology, petrophysics, and reservoir engineering and management has resulted in accurate and meaningful geological and reservoir performance models for this field.
The Chase Group is composed of cyclical sequences deposited on a gently dipping-, low-relief, shallow marine shelf. Each cycle comprises laterally continuous, successively shallower water, marine carbonate (chiefly dolostone), siltstone and sandstone reservoir units capped and separated by shaly redbeds and paleosols. The lateral continuity, low permeability, and high threshold entry pressures of shaly layers produce effective regional barriers that prevent vertical fluid flow and pressure communication between reservoir layers. Although variable, depending on depositional and diagenetic history, porosity is continuous within a reservoir layer because of a well-developed intercrystalline pore network produced by pervasive dolomitization independent of depositional texture and other pore types.
Pressure differences measured between reservoir layers verify predicted reservoir and barrier qualities. A study of 83 replacement wells failed to identify any original field pressures (490 psia), indicating no significant volumes of gas not in communication with producing wells. All replacement well locations, therefore, have contributed to production from the original section well or other offset wells; no new gas-in-place has been found.
Petrophysically unique Archie saturation input parameters were computed based on the abundance of the various lithotypes within each of the reservoir layers. Their incorporation into the log analysis system provided a more accurate determination