Depositional environments of the Mississippian Chappel bioherms, Hardeman County, Texas

Conference · Tue Mar 01 04:00:00 EST 1983 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6421054

Asquith, G B; Allison, M D

Numerous crinoid-fenestrate bryozoan banks are developed within the Mississippian Chappel Formation, located in the Hardeman basin, Hardeman and Wilbarger Counties, Texas. The banks are oval in shape and range in size from 2 to 12 mi (3 to 19 km) in diameter. Stratigraphic, hydrocarbon entrapment in the banks has resulted in cumulative production exceeding 6 million bbl of oil plus 13 bcf of gas. The Chappel Formation is a shallow-water limestone, overlain by the oolitic grainstones of the Mississippian St. Louis Formation. Three distinct Chappel facies can be identified: the bank core, flank, and interbank facies. Bank growth began in a low-energy environment with the mechanical accumulation of lime mud which was baffled and trapped by crinoids and fenestate bryozoan. Once the bank core reached wave-base, the crinoid-bryozoan mudstones and wackestones were reworked and redeposited as the crinoid-bryozoan grainstones and packstones of the flank facies. The extensive development of the flank facies, compared with bank core development, indicates that the top of the bank remained at or near wave-base for an extended period of time. Porosity development in the Chappel banks is secondary and results from dolomitizaiton of the micritic bank core, fracturing and leaching. The Chappel banks can be located in the subsurface by using isopach maps which help identify interval thickening within the Chappel. In subsurface exploration, the bank facies can be differentiated from the interbank facies by petrographic analysis and by noting the more massive and also lower gamma ray log response. The lower gamma ray log response is caused by a lack of argillaceous material in the bank facies.

• Research Organization: Pioneer Production Corp., Amarillo, TX
• OSTI ID: 6421054
• Report Number(s): CONF-8304200-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 67:3
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
DISTRIBUTION
FEDERAL REGION VI
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGIC TRAPS
LITHOLOGY
MINERAL RESOURCES
MISSISSIPPIAN PERIOD
NATURAL GAS DEPOSITS
NORTH AMERICA
PALEOZOIC ERA
PETROLEUM DEPOSITS
POROSITY
RESERVOIR ROCK
RESOURCES
SPATIAL DISTRIBUTION
TEXAS
USA