--> Abstract: Organic Facies, Source-Rock Potential of Jurassic-Cretaceous Organic-Rich Rocks and Genesis of Light Oil and Condensates from the Scotian Shelf, Eastern Canada, by P. K. Mukhopadhyay, J. A. Wade, M. A. Kruge, and M. G. Fowler; #91012 (1992).

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ABSTRACT: Organic Facies, Source-Rock Potential of Jurassic-Cretaceous Organic-Rich Rocks and Genesis of Light Oil and Condensates from the Scotian Shelf, Eastern Canada

MUKHOPADHYAY, P. K., Global Geoenergy Res. Ltd., Halifax, Nova Scotia; J. A. WADE, A. G. C. Geological Survey Canada, Dartmouth, Nova Scotia, Canada, M. A. KRUGE, Southern Illinois University, Carbondale, IL, and M. G. FOWLER, Geological Survey of Canada, Calgary, Alberta, Canada

An organic facies and source rock characterization of mainly organic-rich rocks (from more than 250 cuttings and core samples of various Jurassic and Cretaceous formations) was done using organic petrography, Rock-Eval pyrolysis, liquid chromatography, gas chromatography, stable carbon isotopes, and GC-MS (aromatic fraction).

These data suggest the presence of multiple condensate and/or gas-bearing source rocks (type IIB, IIB-III, and III) which are associated with minor local oil-prone source rocks (types IIA and IIA-IIB); none of these source rocks were formed in an anoxic environment. Vitrinite reflectance and fluorescence of matrix bitumen and kerogen suggest the possible presence of deeper condensate in the basin and indicate the possible timing of overpressuring.

The stable carbon isotope and chromatography data indicate that the light oils and condensates can be grouped into three possible families. The GC-MS data of the aromatic fraction of light oil and condensate samples, when compared with stable carbon isotope, GC of both light and C12+ hydrocarbons and liquid chromatography, reveal the following: Cohasset-Panuke-Sable Island oils belong to a nonthiophenic (low-sulfur) group possibly derived from lacustrine algal type I or IIA source rock and the South Venture/Glenelg condensates belong to a moderately thiophenic group derived from a marine type II-III source rock. Based on Methyphenanthrene Index and the ratio of chrysene to benzo (<falpl>)-anthracene, Cohasset-Panuke oils are less mature than Venture condensates, both of which ar formed within the "oil window."

 

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