--> Abstract: Reservoirs of the Bakken Petroleum System: A Core-based Perspective, by Julie A. LeFever, Richard D. LeFever, and Stephan Nordeng; #90169 (2013)

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Reservoirs of the Bakken Petroleum System: A Core-based Perspective

Julie A. LeFever, Richard D. LeFever, and Stephan Nordeng
North Dakota Geological Survey

The high level of activity in the Bakken Petroleum System has resulted in significant increase in available data. Log data is unreliable in determination of reservoir properties and has prompted the increased level of coring in an attempt to understand the reservoir. Nine potential reservoirs have been identified within the petroleum system. Production is well established from some, limited from others, and waiting to be tested in others. The informal members within the Three Forks Formation provide four potential reservoirs consisting of brecciated dolo-mudstones, an interbedded sequence of claystones and dolomitic mudstones, with each reservoir capped by an anhydrite or an argillaceous mudstone. These were deposited on a prograding carbonate shoreline, largely in tidal flat or supratidal settings. The Bakken Formation unconformably overlies the Three Forks. Its basal member, the Pronghorn consists of Skolithus sandstones, silty- to sandy-dolomitic mudstones, brachiopod-bearing lime mudstones, and a cherty limestone with the reservoir facies limited to the sandstone and dolomitic mudstone facies representing shoreface to nearshore deposits. Mixed carbonates and siliclastics of the Middle Member comprise the next reservoir in the system representing variable shallow environments. Black organic-rich shale of the Upper Member is considered as one of the source beds, as well as a reservoir. Immediately overlying the Bakken is the Lodgepole Formation. The basal nodular-bedded, crinoidal-rich limestone, as well as its dark organic-rich limestone may provide two additional targets. The unconventional nature of the reservoirs requires wells to be fracture stimulated to produce. Cored sections provide a window into the effectiveness of the stimulation procedures.

AAPG Search and Discovery Article #90169©2013 AAPG Rocky Mountain Section 62nd Annual Meeting, Salt Lake City, Utah, September 22-24, 2013