Three ancient Montana fluvial systems: Pennsylvanian Tyler, Lower Cretaceous Muddy, and Upper Cretaceous Eagle - their reservoir and source rock distribution

Conference · Wed May 01 04:00:00 EDT 1985 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6010662

Shepard, B

The importance of using Holocene geology as a model in mapping reservoir and source rock distribution is demonstrated in three Montana river-related systems: alluvial valley, barrier bar, and distributary channel-prodelta. The Pennsylvanian Tyler Formation was deposited by a westward-flowing meandering-stream system controlled by an east-west-trending rift valley, and surrounded by backswamp deposits. It is underlain by its probable hydrocarbon source, the marine Mississippian Heath shale and limestone, and overlain locally by the lagoonal Pennsylvanian Bear Gulch Limestone. To date, about 90 million bbl of recoverable oil have been found in Tyler sands. The oil-producing Lower Cretaceous Muddy sandstones in the northern Powder River basin are considered to be barrier bars, encased in organic-rich shales, which are most probably the source rock. The Upper Cretaceous Eagle Sandstone in north-central Montana is a distributary channel system, similar to that of the modern Mississippi, which dumped highly carbonaceous materials into an organic-rich delta system. The Eagle now contains possibly enormous amounts of biogenic methane. By using Galveston Island and the modern Mississippi delta as models, in conjunction with employing electric log shapes and porosity logs, it is possible to map ancient fluvial patterns in the study areas. One can then predict the location of possible hydrocarbon accumulations in porous and permeable sand bodies, along with their encasing hydrocarbon source rocks.

• Research Organization: Infinity Oil Co., Billings, MT
• OSTI ID: 6010662
• Report Number(s): CONF-8506201-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 69:5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
CARBONATE ROCKS
CRETACEOUS PERIOD
DEPOSITION
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
LIMESTONE
MESOZOIC ERA
MINERAL RESOURCES
MONTANA
NORTH AMERICA
PALEOZOIC ERA
PENNSYLVANIAN PERIOD
PETROLEUM DEPOSITS
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SHALES
SOURCE ROCKS
USA