Diagenesis of sandstones in Permian upper Minnelusa Formation, west Mellott field, Powder River basin, Wyoming
Dolomite-anhydrite-sandstone cycles of the Permian upper Minnelusa Formation, Wyoming, record multiple progradations of marine, siliciclastic sabkha, and eolian sediments. Heterogeneity in the sandstones, studied in five cores from present-day depths between 7100 and 7300 ft, is partly the result of diagenetic alterations. Late-stage dissolution of anhydrite produced irregularly distributed secondary sandstone porosity that ranged to approximately 30%; dissolution was most complete in the upper parts of eolian-dune and reworked-eolian sandstones, resulting in excellent reservoir properties. Late-stage dissolution of potassium feldspars also occurred, as evidenced by the lack of compaction of the partially dissolved grains. Hydrocarbons then migrated into and occupied the secondary porosity of the upper parts of eolian-dune sandstones and reworked-eolian sandstones at West Mellott. Small rhombs of authigenic dolomite grew along most of the secondary pores and partially replaced the remaining anhydrite. Quartz overgrowth cement formed subsequent to the dolomite, in some cases engulfing the dolomite rhombs in syntaxial overgrowths. Pyrite appears to be a late authigenic phase that automorphically replaced anhydrite, quartz, and dolomite.
- Research Organization:
- Geological Survey, Denver, CO (USA)
- OSTI ID:
- 6014840
- Report Number(s):
- CONF-880301-
- Journal Information:
- AAPG Bull.; (United States), Journal Name: AAPG Bull.; (United States) Vol. 72:2; ISSN AABUD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
DIAGENESIS
DRILL CORES
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
MINERAL RESOURCES
MONTANA
NORTH AMERICA
PALEOZOIC ERA
PERMIAN PERIOD
PETROLEUM DEPOSITS
POROSITY
POWDER RIVER BASIN
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
USA
WYOMING