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Williston Basin Oil Exploration: Past, Present, and Future

JENNINGS, ARNOLD H., Lakewood, CO

Past: In 1951, modern oil exploration came to the Williston basin with the discovery of Paleozoic oil on the large Nesson anticline. This was quickly followed by similar discoveries on Cedar Creek and Poplar anticlines. To the north, the Canadians, lacking large structures, concentrated on Paleozoic stratigraphic traps and were highly successful. U.S. explorationists quickly followed, finding similar traps on the basin's northeastern flank and center.

The 1960s saw multiple Devonian salt dissolution structures produce on the western flank. To the northwest, shallow Mississippian and deeper Ordovician pays were found on small structural closures. These later were combined with pays in the Devonian and Silurian to give multiple pay potential. In the basin center large buried structures, visible only to seismic, were located.

The 1970s revealed an Ordovician subcrop trap on the southeast flank. Centrally, a Jurassic astrobleme with Mississippian oil caused a flurry of leasing and deep drilling.

The 1982 collapse of oil prices essentially halted exploration. 1987 saw a revival when horizontal drilling for the Mississippian Bakken fractured shale promised viable economics.

Present: Today, emphasis is on Bakken horizontal drilling in the deeper portion of the basin. Next in importance is shallow drilling such as on the northeastern flank.

Future: An estimated one billion barrels of new oil awaits discovery in the Williston basin. Additional exploration in already established production trends will find some of this oil. Most of this oil, however, will almost certainly be found by following up the numerous geological leads hinted at by past drilling.

 

AAPG Search and Discovery Article #91010©1991 AAPG Rocky Mountain Section Meeting, Billings, Montana, July 28-31, 1991 (2009)