Date of Award
Master of Science
Geological and Environmental Sciences
Dr. William Harrison III
Dr. David Barnes
Dr. John Grace
Masters Thesis-Open Access
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.
Dellapenna, Timothy M., "Sedimentological, Structural, and Organic Geochemical Controls on Natural Gas Occurrence in the Antrim Formation in Otsego County, Michigan" (1991). Master's Theses. 975.