--> Abstract: Geochemical and Lithological Constraints for Bakken Shale Production, by H. Von Der Dick, L. Druyff, M. Frytt, and R. Clark; #91012 (1992).

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ABSTRACT: Geochemical and Lithological Constraints for Bakken Shale Production

VON DER DICK, H., Canadian Hunter Exploration Ltd., Calgary, Alberta, Canada, L. DRUYFF and M. FRYTT, American Hunter Exploration, Denver, CO, and R. CLARK, Canadian Hunter Exploration Ltd., Calgary, Alberta, Canada

An integrated study on Bakken shale samples using geochemical and lithological methods combined with regional geologic/tectonic data allow us to confine areas of favorable Bakken oil production and increase chances of economic success. Sufficient organic carbon and a narrow thermal maturity window in the late maturity stage are important constraints on oil production. Well performance shows a positive correlation with subtle maturity changes obtained from biomarker geochemistry. This observation could be explained by the collapse and intense conversion of kerogen into hydrocarbon liquids at late mature conditions and the formation of secondary porosity/permeability as a result of kerogen destruction in the Bakken. SEM studies on cores support this explanation.

Further important constraints are the developments of fractures in the shale. Several types of fractures, including expulsion fractures, have been identified. All fractures are lithology dependent and were developed at or after hydrocarbon generation. Regional, tectonic fractures appear to be basement controlled. Consequently, optimum Bakken shale production is achieved in areas of high maturity favoring expulsion fractures, secondary porosity, and light oil, and tectonic fracturing providing regional drainage. Basement tectonics fracturing the Bakken may also be important for increased paleo-heat flow resulting in increased maturity levels in favorable regions.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)