Mid-Continent Section

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Pennsylvanian source rocks in the Anadarko Basin: An example from the Missourian series Hogshooter Formation in Mills Ranch Field (TX & OK)


Previous studies within the Anadarko Basin highlight the potential of Pennsylvanian mudstones/shales as viable hydrocarbon sources. However, unlike source rocks in the Ordovician and Devonian-Mississippian petroleum systems, where geochemically validated examples of sourcing exist, those of the Pennsylvanian system lack clear ties. This study highlights the hydrocarbon-source relationship within Mills Ranch field (Hogshooter Formation: Missourian Series) along the Texas and Oklahoma border by demonstrating the link between produced oils/condensates and Missourian shales. Bitumen extracts from two cores in the Hogshooter portion of the field were used to link the produced liquids to Missourian source beds. To validate geochemical correlation parameters, low maturity extracts from non-Missourian source facies within the Anadarko basin and Woodford Shale produced oils were analyzed. Based on gas chromatography, coupled gas chromatography/mass spectrometry, and stable carbon isotope analyses, the light oils and condensates produced from Mills Ranch field are genetically related to local Missourian mudstones/shales. There is one primary type-II organic-facies that is geochemically tied to the produced liquids. Models for the distribution of the primary source-facies have led to an improved assessment of the Mills Ranch field Missourian section, and a better understanding of the economic potential of Pennsylvanian shales in the Anadarko Basin.