Willard J. Guy1,
Alan P. Byrnes1,
Martin K. Dubois1
(1) Kansas Geological Survey, Lawrence, KS
Abstract: Petrophysical reservoir characterization in the Council Grove Group (Lower Permian) in the 21st Century: Panoma Field, Hugoton Embayment, Kansas
Gas production from the Panoma Field within the Hugoton Embayment in southwest Kansas and northwest Oklahoma is from stacked reservoirs in the Council Grove Group (Lower Wolfcampanian) carbonates. the Panoma Field presently has over 2500 producing wells and has produced over 2.5 trillion cubic feet of gas. the field underlies the giant Hugoton Gas Field, which produces from the overlying Chase Group (Upper Wolfcampanian) cyclical carbonates.
The primary reservoir facies are gray bioclastic grainstone-packstone limestones that were deposited in a mosaic or series of bioclastic marine shoals. Intergranular, moldic and vuggy porosity varies up to 20% with 8 to 10% being considered the lower limit fro economic production. Permeability is erratic with 0.1 md considered to be the lower economic limit. The most effective ore type is intergranular. Producing grainstone-wackestone reservoirs are separated by thick (10 to 15 ft) red-brown to green-gray calcareous slightly argillaceous siltstones with low permeability and porosity. This siltstone is interpreted as a coastal plain to paleosol deposit.
Wireline analysis indicates that the water saturation is relatively high (50 to 70%), while the bulk volume water is intermediate (5 to 8%). The determination of effective porosity is critical to the reservoir characterization of the Council Grove. Laboratory NMR, wireline NMR data and capillary pressure data indicates that the effective porosity ca be considerably less than the total NMR and core porosity primarily as a result of dolomitization of the micritic matrix, intraparticle and fine intercrystalline pores within a chert replacement, and microporosity.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana