Energy Policy Act of 2005 (Ultra-deepwater and Unconventional Resources Program)
Enhanced Oil Recovery from the Bakken Shale Using Surfactant Imbibition Coupled with Gravity Drainage
University of North Dakota
Champion Technologies, Tiorco-Stepan, and Hess Corporation
The objective of this project is to determine whether surfactant solutions can alter the wettability of the Bakken shale (in North Dakota’s Williston Basin), so that oil recovery can be enhanced by a mechanism involving imbibition and gravity drainage.
With the low permeability and oil-wet character, using existing methods, oil recovery factors have only been a few percent of original oil in place. This research project will investigate whether a new surfactant imbibition concept can significantly improve oil recovery from the Bakken shale. This concept involves formulating special surfactant solutions that will alter the wettability of the formation, without causing formation damage. This alteration should promote imbibition of a dilute aqueous surfactant solution and increase oil displacement from the shale. The concept also relies on exploitation of gravity for collection and recovery of the oil in the system of natural and hydraulic fractures that are connected to horizontal wells. The concept has been applied in a low-permeability sandstone reservoir and currently is under investigation in a low-permeability chalk reservoir in offshore Norway and in a low-permeability carbonate reservoir in the United States.
In this project, the degree of imbibition will be tested for available waters in different portions of the Bakken shale, to establish their true wetting state. The researchers will investigate whether imbibition can be induced using only pH or salinity variations. Then a number of surfactants will be tested to identify formulations that will promote maximum imbibition into and oil displace-ment from Bakken shale cores. Measurements of phase behavior, interfacial tension, surfactant adsorption, and imbibition will be an important part of this effort. Based on these laboratory re-sults, a numerical model will be produced that incorporates the relevant physics of surfactant im-bibition and oil displacement for the Bakken shale. This model will then be used to assess the potential of this surfactant imbibition process for existing completions within the Bakken shale and assess whether alternative well completion/fracture configurations might provide higher oil recoveries. In the Bakken shale formation, an increase of 1% in recovery could lead to an increase of 2 - 4 billion barrels of domestic oil production. The University of North Dakota will team with one or more small producers during this project, so that developments can be rapidly field tested.
Champion Technologies, Tiorco-Stepan, and Hess Corporation will participate in this project. The proposed cost share has been requested from the North Dakota Industrial Commission.
Principal Investigator: Dr. Dongmei Wang