Date of Award

4-1991

Degree Name

Master of Science

Department

Geosciences

First Advisor

Dr. William Harrison

Second Advisor

Dr. David Barnes

Third Advisor

Dr. John Grace

Access Setting

Masters Thesis-Open Access

Abstract

The prolific Antrim Formation natural gas reservoir in Otsego County, Michigan, has been examined using core descriptions, X-ray diffraction, petrographic, and geochemical analyses. New stratigraphy nomenclature is proposed for the Antrim and Ellsworth Shales. The Antrim Shale contains two distinctive lithofacies: (1) a fractured, non-bioturbated, silica-rich, organicrich black shale lithofacies; and (2) sparsely fractured, bioturbated, carbonaterich, organic-poor gray-green shale. Gas production comes from the Black shale facies.

Rock-Eval analysis demonstrates that the organic matter is a mixture of types I and II material. Low Tmax (435°C) and vitrinite reflectance (0.41-0.46%) values indicate a submature thermal maturation level. Del 13 carbon isotope analysis of produced gas samples demonstrates that the thermal maturation of the gas and the Antrim source beds are correlative. High SI values (8.25 milligrams free oil /gram of rock) and physical observations of oil staining demonstrate that Antrim oil has been generated.

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