Regional-scale flow of formation waters in the Williston basin

Journal Article · Thu Feb 01 04:00:00 EST 1996 · AAPG Bulletin

OSTI ID:232993

Bachu, S ^[1]; Hitchon, B ^[2]

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1. Alberta Department of Energy, Edmonton (Canada)
2. Hitchion Geochemical Services Ltd., Alberta (Canada)

The Williston basin is a structurally simple intracratonic sedimentary basin that straddles the United States-Canada border east of the Rocky Mountains and that contains an almost continuous stratigraphic record since the Middle Cambrian. Based on the wealth of data generated by the oil industry, the regional-scale characteristics of the flow of formation waters were analyzed for the Canadian side of the basin, and integrated with previous studies performed on the American side. Several aquifers and aquifer systems identified in the basin were separated by intervening aquitards and aquicludes. The Basal, Devonian, and Mannville (Dakota) aquifers are open systems, being exposed at the land surface in both recharge and discharge areas. Recharge takes place in the west-southwest at relatively high altitude in the Bighorn and Big Snowy mountains and at the Black Hills and Central Montana uplifts, whereas discharge takes place in the east and northeast at outcrop along the Canadian Precambrian shield in Manitoba and the Dakotas. The Mississippian and Pennsylvanian aquifer systems are semi-open, cropping out only in the west-southwest where they recharge, but discharging in the northeast into adjacent aquifers through confining aquitards. On regional and geological scales, the entire system seems to be at steady-state, although locally transient flow is present in places due to water use and hydrocarbon exploitation, and to some erosional rebound in the uppermost confining shales. On the western flank of the basin, the interplay between the northeastward structural downdip direction and the northeastward flow of formation waters creates conditions favorable for hydrodynamic oil entrapment.

• OSTI ID: 232993
• Journal Information: AAPG Bulletin, Journal Name: AAPG Bulletin Journal Issue: 2 Vol. 80; ISSN 0149-1423; ISSN AABUD2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
58 GEOSCIENCES
AQUIFERS
FLUID FLOW
GEOLOGIC TRAPS
GEOMETRY
GROUND WATER
PETROLEUM DEPOSITS
STRATIGRAPHY
WILLISTON BASIN