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TOC and Mineralogical Trends in the Utica Shale of Ohio

Harrington, Jake; Cole, David R.; Sheets, Julie; Swift, Alexander M.; Murphy, Michael; Welch, Sue

The recent shale gas boom has brought much attention to Ohio because of its location above the Utica Shale, an Ordovician age rock formation that acts as both a source rock and reservoir rock for large amounts of hydrocarbons. The goal of this research is to determine the mineralogy and total organic carbon (TOC) of Utica Shale samples and to determine the relationships among these data with depth and east-west location. Utica shale samples were collected from six wells from northwest to southeast Ohio and one from western West Virginia. Core samples were obtained from the Ohio Geological Survey, Ohio Division of Natural Resources. The mineralogical analysis focuses on the amount of clay minerals with respect to non-clay minerals. Powder X-ray diffraction analysis using a PANalytical of randomly-oriented powder samples is employed to determine the qualitative and quantitative mineralogy. TOC is measured using a Costech elemental analyzer after treating each sample with acid to dissolve inorganic carbon. The lithology of the Utica samples measured is variable, ranging from clay-dominated mineralogy to carbonated-dominated mineralogy. The TOC ranges from about 0.5 to 3.3 weight percent in the seven samples analyzed. Although TOC is variable, in general, higher values are measured toward eastern Ohio/western West Virginia. Also in general, higher TOC values are associated with higher clay content. This information could help locate drilling sites and lead to newly discovered shale gas plays.


AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013