CHEMOSTRATIGRAPHY AND CT-IMAGE AIDED LITHOFACIES ANALYSIS OF A MIDDLE DEVONIAN MARCELLUS SHALE WELL IN NORTHERN WEST VIRGINIA, USA

The Marcellus Shale Energy and Environmental Laboratory (MSEEL) is a collaborative field project led by West Virginia University, Northeast Natural Energy LLC, several industrial partners, and the National Energy Technology Laboratory of the US Department of Energy. MSEEL consists of two project areas within the dry gas producing region of the Marcellus shale play in Monongalia County, West Virginia. The focus for this study is on the Morgantown Industrial Park (MIP) project area.

Drilled in the fall of 2015, the MIP 3H vertical pilot well was cored between depths of 7445 to 7557 feet, encompassing the base of the Mahantango to the top of the Onondaga. Core analysis including medical computed tomography (CT) scans, multi-sensor corelogger data (gamma density, p-wave velocity, and magnetic susceptibility), chemostratigraphy determined from handheld X-Ray fluorescence, and determination of total organic content.

Lithofacies analysis was determined at the core-scale using traditional core description techniques, in addition to using medical CT-scan images to distinguish lithofacies using pixel classification. Pixel classification is trained by the end-user on facies/features representative of the stratigraphy and predicted through the remainder of the core volume. This method allows for a three-dimensional visualization of lithofacies and unique features (i.e. pyrite and calcite fractures).

The MIP 3H core contains six shale lithofacies core. The pixel classification methods used distinguishes three facies from texture alone and can be discriminate further with the addition of slice-averaged grayscale and geochemical data (separates gray/black facies, organic/inorganic, and carbonate-richness).

Chemostratigraphically we find that black organic-rich facies show an increase in paleo-productivity (increases in Ni, Zn, and V), decrease in sedimentation (decreases in detrital proxies), and anoxic to euxinic conditions (increases in Mo and chalcophiles). Paleo-redox conditions in both wells are dynamic throughout deposition transitioning between euxinic/anoxic to disoxic/oxic, seen through the calcite/pyrite concretion distribution segmented from the CT-image and the elemental data trends.