Thermal maturity of organic matter in Green River formation, Piceance Creek basin, Colorado

Conference · Sun Apr 01 04:00:00 EST 1984 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6569700

Johnson, R; Nuccio, V F

The thermal maturity of organic matter in the Green River Formation in the Piceance Creek basin was determined by vitrinite reflectance on coalified logs in the otherwise alginite-rich oil shale, marlstone, and sandstone. Only vitrinite from logs in sandstone and marlstone was used to determine thermal maturity because reflectance of vitrinite from alginite-rich oil shale generally is lower than that in associated other rock types. Mean random vitrinite reflectance (R/sub 0/) at the top of the Green River Formation ranges from about 0.30% around the perimeter of the basin, where maximum burial depth of the rocks was less than 1000 m (3300 ft), to 0.55% in the structurally lowest part of the basin, where maximum burial depth of the upper part of the Green River Formation is almost 1200 m (3900 ft) thick in the structurally lowest part of the basin, suggesting that the lower part of the formation in this area may have reached an R/sub 0/ of 0.7%, generally accepted as the threshold for oil generation in alginitic rocks. Bitumin filled fractures observed in core from this area of the basin support this conclusion. A lithologically similar lacustrine section of the Green River Formation in the adjacent Uinta basin, where maximum burial was as great as 5600 m (18,400 ft), is producing large quantities of oil from over-pressured, fracture-controlled reservoirs. Present-day maximum temperatures in the Green River Formation in the Piceance Creek basin are between 55 and 70/sup 0/C (131 and 158/sup 0/F). This temperature seems too low for hydrocarbon generation. However, temperatures in the past probably were high enough for hydrocarbon generation. Oil generated during this earlier, hotter period could have migrated into conventional stratigraphic and structural traps.

• Research Organization: Geological Survey, Denver, CO
• OSTI ID: 6569700
• Report Number(s): CONF-8405216-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 68:4
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200 -- Petroleum-- Reserves
Geology
& Exploration
04 OIL SHALES AND TAR SANDS
040100* -- Oil Shales & Tar Sands-- Reserves & Exploration-- (-1989)
BITUMENS
COLORADO
FEDERAL REGION VIII
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
GEOLOGY
GREEN RIVER FORMATION
MACERALS
MATURATION
MINERAL RESOURCES
NORTH AMERICA
OIL SHALE DEPOSITS
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
PETROLEUM DEPOSITS
PICEANCE CREEK BASIN
RESERVOIR ROCK
RESOURCES
SEDIMENTARY BASINS
TAR
USA