Journal of Petroleum Geology, Vol.9, No.3, pp. 313-342, 1986

©Copyright 2000 Scientific Press, Ltd.

ORGANIC METAMORPHISM IN THE LOWER MISSISSIPPIAN-UPPER DEVONIAN BAKKEN SHALES II: SOXHLET EXTRACTION *

Leigh C. Price, Tom Ging, Alonza Love and Don Anders**

* Appreciation is extended to Joel Levanthal and Chuck Spencer for reviewing the manuscript and to the North Dakota Geological Survey, especially Sidney Anderson, for their cooperation.

** US Geological Survey, PO Box 25046, Denver Federal Center, Denver, CO 80225, USA.

Abstract

In this paper, we report on Soxhlet extraction (and subsequent related analyses) of 39 Lower Mississippian- Upper Devonian Bakken shales from the North Dakota portion of the Williston Basin, and analyses of 28 oils from the Basin. Because of the influence of primary petroleum migration, no increase in the relative or absolute concentrations of hydrocarbons or bitumen was observed at the threshold of intense hydrocarbon generation (TIHG), or during mainstage hydrocarbon generation in the Bakken shales. Thus, the maturation indices that have been so useful in delineating the TIHG and mainstage hydrocarbon generation in other studies were of no use in this study, where these events could clearly be identified only by Rock-Eval pyrolysis data.