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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 55 (1971)

Issue: 2. (February)

First Page: 354

Last Page: 354

Title: Geologic Factors Which May Affect Gas Occurrence in Anadarko Basin, Oklahoma: ABSTRACT

Author(s): Carl A. Moore

Article Type: Meeting abstract

Abstract:

The Anadarko basin in Oklahoma, the Texas Panhandle, and in southwestern Kansas contains many reservoirs which produce commercial quantities of gas with subordinate quantities of oil. The producing formations are Permian; Upper, Middle, and Lower Pennsylvanian; Upper and middle Mississippian; Hunton; and Ordovician. Each of these groupings can be considered a genetic stratigraphic unit in which the depositional and structural history is closely related.

Gas analysis is a powerful tool in the exploitation of a given reservoir. Some reservoirs in the Anadarko basin are blanket-type sandstones in which the analyses will be uniform over a broad area. Gas analyses showing abnormally high BTU values, subnormal formation pressures, or exceptionally high nitrogen content can be producing from a sandstone lens (either channel or offshore bars) or a limited carbonate porosity zone in which there has been no communication of fluids.

Hunton gas analyses show a higher percentage of CO2 at depth, whereas the BTU values decrease because of the decreasing percentage of gas liquids below 14,000 ft. Pressures in the Hunton, although a little below the so-called normal bottomhole pressures, increase in a fairly uniform manner. The Morrow sandstones are productive over most of the Anadarko basin. Variations in the analyses from these sandstones appear to depend on the depth of production and on the chemical content of the gases. It is evident that many of the anomalous values of the analyses depend on the extent of the local reservoir and its geometry.

Gas analyses are a major factor in the economics of gas production. The Hunton gases along the northern shelf of the Anadarko basin yield high percentages of valuable gas liquids. Other zones yield variable amounts of gas liquids. Nitrogen values are small in all reservoirs except in the Permian where several "noninflammable" gases are reported. In contrast with the Oklahoma and Texas panhandle gas production, helium does not appear to be a factor--only traces to less than 1.0% helium are reported.

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Copyright 1997 American Association of Petroleum Geologists