X-Ray Computed Tomography of the Utica Shale
Kackley, Derek A.; Cook, Ann; Cole, David R.; Murphy, Michael; Welch, Sue; Sheets, Julie
In this research, we use X-ray computed tomography (XCT) to investigate cores from the Utica (Pt. Pleasant) formation in Ohio. XCT is a non-destructive technology that can image the interior of cores; the 3-D images produced correlate closely to the density of the material. In the Utica shale, we are particularly interested in low-density sections of the core. Organic carbon is of lower density (~1.1g/cm3) compared to the surrounding shale matrix (~2.40g/cm3) so it is hypothesized that the areas of low density contain the largest amount of organic carbon. XCT also images fractures and pyrite in the shales, which is indicative of a presence of organic carbon, and bioturbation, which can indicate a lack of organic carbon. Our previous work on the Utica Shale samples, yielded volume estimates of these low density areas that ranged from 7 to 30 percent of the total core, and were gathered from samples from Wood County, West Virginia. Current work focuses on calibrating the XCT instrument specifically for the shale samples, and on refining the calculations of the volume of these low density areas. This effort involves taking shale samples exhibiting well defined regions of either low or high density and measuring the total organic carbon (TOC) for these areas using a Costech elemental analyzer. If we find a correlation between XCT density and TOC we can then rapidly assess the TOC for an entire core.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013