Depositional environments, sequence stratigraphy, and trap configuration of lower Wolfcampian clastics along eastern edge of Midland basin, west Texas
The Lower Permian (lower Wolfcampian) along the eastern edge of the Midland basin, west Texas, is characterized by ramp-type shelf margins. During eustatic lowstand, nearshore sedimentation shifted drastically to the west into a basinal setting below the Pennsylvanian (Canyon) shelf margin. Core descriptions demonstrate that lowstand systems tract (LST) and transgressive systems tract (TST) siliciclastics were deposited in deltaic and coastal-plain environments. Prodelta, delta-front, and stream-mouth bar facies are associated with the LST. Coastal-plain and distributary channels are preserved in the TST. The sequence stratigraphic framework indicates type 1 sequence boundaries at 287 Ma, 282 Ma, and 280 Ma in the lower Wolfcampian clastics. This lower Wolfcampian package of sedimentary rocks overlies the Pennsylvanian and is capped by the 279-Ma middle Wolfcampian unconformity. All three sequence boundaries and associated systems tract deposits exhibit a prograding stacking pattern within the sequence stratigraphic framework. Basinally restricted prograding LST deltaic rocks are overlain by backstepping TST deltaics and highstand systems tract (HST) outer marine shales. Production in lower Wolfcampian clastic fields is associated with fine-grained quartzarenites up to 45 ft thick which were deposited in stream-mouth bars. Delta-front and prodelta low-permeability shales encase the reservoir facies, forming lateral permeability barriers. HST outer marine shales deposited over the stream-mouth-bar sandstones act as a top seal, creating a stratigraphic trap and providing source for the high-BTU gas and oil produced from these basinally restricted LST deltaics.
- Research Organization:
- Exxon Co., Midland, TX (USA)
- OSTI ID:
- 5798991
- Report Number(s):
- CONF-890404-
- Journal Information:
- AAPG Bull.; (United States), Vol. 73:3; Conference: AAPG annual convention with DPA/EMD Divisions and SEPM, San Antonio, TX, USA, 23-26 Apr 1989
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PETROLEUM DEPOSITS
GEOLOGIC TRAPS
RESERVOIR ROCK
TEXAS
ALLUVIAL DEPOSITS
CARBONATE ROCKS
PENNSYLVANIAN PERIOD
PERMIAN PERIOD
SANDSTONES
SEDIMENTARY BASINS
FEDERAL REGION VI
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
MINERAL RESOURCES
NORTH AMERICA
PALEOZOIC ERA
RESOURCES
ROCKS
SEDIMENTARY ROCKS
USA
020200* - Petroleum- Reserves
Geology
& Exploration