Integrated geochemical, mechanical, and lithological characterization of the Marcellus Shale, Pennsylvania

Abstract

The middle Devonian (392-387 Ma) Marcellus Shale is one of the primary targets for unconventional drilling in the Appalachian basin. Despite its often homogenous and fine-grained appearance, the Marcellus Shale was deposited under varying environmental conditions, which can lead to subtle differences in fabric and texture not readily identifiable by conventional low resolution sampling and analysis. This study incorporates high resolution geochemical, mechanical, and lithological characterization from two vertical cores to assess vertical and lateral heterogeneity of the Marcellus Shale in northern Appalachian basin. Detailed analysis were also performed to understand the sediment flux, paleoproductivity and paleoredox conditions during Marcellus deposition. Interpretation of the various analytical results suggests that the Marcellus Shale is vertically and laterally heterogeneous. Redox-sensitive trace elements also suggest that the Marcellus Shale was most likely deposited in predominantly anoxic deep-water conditions.