Breaking into Bakken potential on the Fort Peck reservation, northeastern Montana

Conference · Sat Jun 01 00:00:00 EDT 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5791974

Monson, L M; Lund, D F ^[1]

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1. Fort Peck Tribes, Poplar, MT (United States)

Necessary ingredients for a Bakken play involve overpressuring, thermal maturity, stratigraphic thinning, hydrocarbon content, and the presence of fractures to free the oil. Bakken thickness varies on the reservation from 0 to 25 m. The Upper Shale Member is uniformly 3-4 m. Thickness is related to a northwest structural grain, especially in the northeast where fold axes are located parallel to the Opheim syncline. This strike is coincident with the general salt solution edge of the Devonian Prairie Evaporites. The Bakken is about 16 m thick along this dissolution boundary and may contain the necessary fracturing. Structural flexure near the Wolf Creek Nose, and especially off the northeast and eastern flanks of the Poplar dome, may have suitably fractured the Bakken as well. Well logs in this area have good resistivity separation in the Middle Siltstone Member of the Bakken, which may be used to detect fracturing in this low-porosity reservoir. Present depth of the Bakken varies from about 2,100 to 3,050 m. Electrical resistivities indicate, however, that much of the reservation's Bakken was subjected to sufficient depths to generate hydrocarbons. Other physical properties, based on porosity and gamma-ray logs, confirm that organic carbon content is adequate, if not exceptionally high. Regional and Laramide uplift, coupled with glacial erosion and rebound, probably explain the present elevation of the Bakken in this area. Significant overpressuring exists in the Bakken over at least half of the reservation as determined by sonic-log calculations and sparse drill-stem test pressures.

• OSTI ID: 5791974
• Report Number(s): CONF-9107109-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 75:6; Conference: American Association of Petroleum Geologists (AAPG) Rocky Mountain Section meeting, Billings, MT (United States), 28-31 Jul 1991; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
MONTANA
PETROLEUM DEPOSITS
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GEOLOGIC FRACTURES
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MATURATION
POROSITY
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FEDERAL REGION VIII
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