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Paper No. 10
Presentation Time: 8:00 AM-6:00 PM


ADIGWE, Ekenemolise and QUAN, Tracy M., Boone Pickens School of Geology, Oklahoma State University, 105 Noble Research Center, Stillwater, OK 74078,

Stable nitrogen isotopes have been used to trace the origin and fate of sedimentary organic matter in marine environments. Based on this premise, the efficacy of nitrogen isotopes as proxies in the discovery of hydrocarbons and unconventional resources in the Woodford Shale (Upper Devonian-Lower Mississippian) of the Arkoma Basin is explored here. We will present δ15Norg, δ13Corg, and TOC values from 3 different locations within the Woodford, and compare them to conventional petroleum drilling parameters such as resistivity and gamma ray logs. Our results indicate that δ15Norg values are highest in the upper section of the Woodford then decrease with depth. In contrast, δ13Corg values are lowest in the upper section of the Woodford, with a sudden rise in the middle of the measured section, followed by a decrease in the lower section. TOC has a positive correlation with δ15Norg and a negative correlation with δ13Corg. Resistivity is often used by conventional petroleum and gas shale analysis methods to determine the presence of high hydrocarbon concentrations and thus the likelihood of productivity. Samples from outside of the Woodford Shale deposits generally show more enriched nitrogen isotopic values coupled with low resistivity values. In the Woodford, we generally see a decrease in δ15Norg accompanied by an increase in resistivity, though not all samples follow this trend. Our data indicates that there may be a negative correlation between resistivity and δ15Norg.

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