Sedimentology and petroleum occurrence, Schoolhouse Tongue of Weber Sandstone (lower Permian), Northwest Colorado

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6503788

Johnson, S Y; Schenk, C J; Anders, D E; Tuttle, M L

The Schoolhouse Tongue of the Weber Sandstone, an extensive paleo-petroleum reservoir in northwest Colorado, consists mainly of bleached or oil-stained sandstone of inferred eolian sand-sheet origin. Low-angle to parallel-bedded, very fine to fine-grained sandstone is the dominant facies. Low-angle deflationary surfaces and deflation lags are common. Cross-bedded dune deposits are a less common sand-sheet facies. Interbedded fluvial deposits are present in most sections. The sand-sheet deposits of the Schoolhouse Tongue are sedimentologically similar to those in the gradationally underlying red beds of the Middle Pennsylvanian to Lower Permian Maroon Formation, and the Schoolhouse Tongue is best constructed as the uppermost sand sheet in the Maroon sequence. At Rifle Creek, the site of a late Paleozoic-early Mesozoic structural high, the Schoolhouse Tongue is 66 m thick and oil staining extends several hundred meters down into the underlying Maroon Formation. Away from Rifle Creek, the Schoolhouse Tongue thins to the north and pinches out to the southeast and east (within 40-65 km), and oil staining in the Maroon is minimal. The distribution of oil-stained rock suggests that hydrocarbons were introduced at a point source, possibly related to faults on the margins of the paleohigh. Oil in the Schoolhouse Tongue mainly occurs in secondary pore space resulting from the dissolution of carbonate cement by migrating organic acids. Oil was trapped below overlying red siltstones. Geochemical typing of the hydrocarbons is consistent with a late Paleozoic source rock.

• OSTI ID: 6503788
• Report Number(s): CONF-880301-
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
CARBON COMPOUNDS
CARBONATES
CHEMISTRY
COLORADO
EXPLORATION
FEDERAL REGION VIII
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC TRAPS
GEOLOGY
MINERAL RESOURCES
NORTH AMERICA
OIL SATURATION
OXYGEN COMPOUNDS
PALEONTOLOGY
PALEOZOIC ERA
PERMIAN PERIOD
PETROLEUM DEPOSITS
PETROLEUM GEOLOGY
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SATURATION
SEDIMENTARY ROCKS
SEDIMENTATION
SOURCE ROCKS
USA