Petroleum source rocks and stratigraphy of Bakken formation in North Dakota

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

OSTI ID:5536279

Webster, R L

The Bakken Formation (Devonian and Mississippian) of North Dakota consists of upper and lower, black, organic-rich shales separated by a calcareous siltstone middle member. Organic-carbon measurements revealed the Bakken shales to be very organic-rich (average of 11.33 wt.% of organic carbon), and visual kerogen typing revealed this organic matter to be predominantly an amorphous type that is inferred to be sapropelic. The onset of hydrocarbon generation was determined to occur at an average depth of 9000 ft (2.74 km) by interpreting plots of geochemical parameters with depth (e.g., ratios of hydrocarbon to nonhydrocarbon, saturated hydrocarbon to organic carbon, pyrolytic hydrocarbon to organic carbon, and the pyrolysis production index). Hydrocarbon content and thermal kerogen breakdown increase greatly in the Bakken shales where they are buried at depths greater than 9000 ft (2.74 km). The effective source area of the Bakken, as determined by maps of the above geochemical parameters, lies mostly in McKenzie, Williams, Dunn, and Billings Counties. Oil generation was probably initiated in the Bakken about 75 Ma (Late Cretaceous) at a temperature of about 100/sup 0/C (212/sup 0/F), with initial expulsion of oil from the Bakken probably occurring 70 Ma (Late Cretaceous). The amount of oil generated by the Bakken in North Dakota, as calculated from pyrolysis data, is 92.3 billion bbl. If only 10% of this oil was actually expelled from the shales, it could easily account for the 3 billion bbl of known type II oil reserves in the Williston basin.

• Research Organization: Exxon Company, Midland, TX
• OSTI ID: 5536279
• Report Number(s): CONF-8408161-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 68:7
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHEMISTRY
DEVONIAN PERIOD
FEDERAL REGION VIII
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
GEOLOGY
HYDROCARBONS
KEROGEN
MATERIALS
MATURATION
MINERAL RESOURCES
MISSISSIPPIAN PERIOD
NORTH AMERICA
NORTH DAKOTA
ORGANIC COMPOUNDS
ORGANIC MATTER
PALEOZOIC ERA
PETROLEUM DEPOSITS
RESOURCES
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SHALES
SOURCE ROCKS
STRATIGRAPHY
USA