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Characterization and origin of natural gases of the Anadarko Basin

Proceedings of a symposium held April 5-6, 1988, at Norman, Oklahoma; cosponsored by the Oklahoma Geological Survey and the U.S. Geological Survey
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Abstract

Natural-gas production in the Anadarko basin is from three geographically separated areas that can be differentiated by age of reservoir and by inferred nature of thermal origin of the gases. In the central basin, nonassociated gases are produced mainly from Upper Mississippian and Pennsylvanian sandstones. Gases become isotopically heavier (δ13C1 values range from -49.8 to -33.2 ppt) and chemically drier (C1/C1–5 values range from 0.74 to 0.99) with increasing level of thermal maturity. Gas samples are from depths as much as 21,600 ft. Gases were generated mainly from interbedded shales with type-III kerogen during the mature and postmature stages of hydrocarbon generation. Deviations from the trend are due to mixing and migration of gases generated at different levels of thermal maturity over the past 250 m.y. In the giant Panhandle-Hugoton field, nonassociated gases are generally produced from Permian carbonates at depths <3,000 ft. Gases display little compositional variation δ13C1 values range from -46.4 to -39.9 ppt, C1/C1–5 values range from 0.69 to 0.96). Because organic-rich, mature source rocks are not present in the area, gases probably were generated in the central basin from Pennsylvanian or older source rocks during the mature stage of hydrocarbon generation. This implies migration over distances as much as several hundred miles. In the Sooner trend, associated gases are produced from Silurian, Devonian, and Mississippian carbonates at depths as great as 9,600 ft and were generated from type-II kerogen during the mature stage of hydrocarbon generation. Associated oil correlates with extracts of the Upper Devonian and Lower Mississippian Woodford Shale. Gases are isotopically lighter (δ13C1 values of -47.3 to -40.6 ppt) and chemically wetter (C1/C1–5 values of 0.67 to 0.99) than those derived from type-III kerogen at an equivalent level of thermal maturity.

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Additional Publication Details

Publication type:
Book chapter
Publication Subtype:
Book Chapter
Title:
Characterization and origin of natural gases of the Anadarko Basin
Series number:
90
Year Published:
1989
Language:
English
Publisher:
Oklahoma Geological Survey
Publisher location:
Norman, OK
Description:
6 p.
Larger Work Type:
Report
Larger Work Subtype:
Other Government Series
Larger Work Title:
Anadarko Basin symposium, 1988 (Circular 90)
First page:
47
Last page:
52
Country:
United States
State:
Oklahoma
Other Geospatial:
Anadarko Basin