Faunal Facies Differences Of The Utica And Lorraine Shales PDF Download

The Ordovician Utica Shale is an extensive and important part of the Appalachian Basin subsurface, providing a source for Paleozoic hydrocarbon reservoirs, acting as an unconventional hydrocarbon reservoir, and of interest as an impermeable cap rock for carbon dioxide sequestration in Cambrian formations. The Utica Shale is mostly in the subsurface, with little outcrops in areas of interest, and those that do exist are typically within the Appalachian Mountains (New York). To observe changes in subsurface formations, a combination of core and well logging can provide an extensive look into the subsurface. Here we present a non-destructive core-logging technique to quickly assess mineralogy variations on the Ordovician Trenton/Lexington Limestone, Point Pleasant Formation, and Utica Shale in Ohio. These core logging results, along with several previously measured core mineralogy, were then correlated to well logging electrofacies to extrapolate mineralogy and rock type from a few location to across the state. These were then mapped to identify controls on deposition during the Upper Ordovician in Ohio. Although typically assumed that the only controls on deposition during this time period are the primarily the Appalachian, and to a lesser extent Michigan, Basins, Precambrian basement structures, such as the Waverly Arch, Utica Mountain Fault, and Harlem Fault, have influence on deposition and sediment mixing also. Finally, the Sebree Trough, which has previously been reported to stop in southwest Ohio, appears to have allowed for dark, calcite-poor shales to continue deposition towards northeast Ohio, as a possible trough-like feature extending off of the Sebree Trough. The Trenton/Lexington Limestones, Point Pleasant Formation, and Utica Shale are not homogenous rock types, deposited across the state, but rather variable in both facies and thickness.