UNDERSTANDING THE RELATIONSHIP BETWEEN THE TAGHANIC UNCONFORMITY AND MARCELLUS SHALE PRODUCTION IN DODDRIDGE AND RITCHIE COUNTIES, WEST VIRGINIA

The Marcellus Shale, a geologic unit that extends from New York, Ohio, Pennsylvania, and West Virginia within the Appalachian region, is the source of trillions of cubic feet of natural gas due to organic-rich properties. The formation of the unit was coupled with a period of eustatic sea-level rise that resulted in reactivation of a peripheral bulge leading to the development of the Taghanic unconformity. Stratal variances within the region are predominately found within the Marcellus Shale as a result of the Taghanic unconformity. Most specifically, in West Virginia, the Taghanic unconformity dominates Marcellus shale thickness deviations. Areas where thickness of the unit varies considerably are located within Doddridge and Ritchie counties. This project aids in understanding stratigraphic inconsistencies and hydrocarbon production variances as a result of the Taghanic unconformity on the Marcellus Shale in Doddridge County as compared to Ritchie County, West Virginia.

Data are derived from log images obtained by the West Virginia Geological and Economic Survey that are correlated to establish the stratigraphy. This study shows the Middle Devonian Marcellus Shale thins from ~60-80ft in the northwest to ~40-60ft in the southwest of the counties. This is accomplished by depositional thinning of the lower Marcellus Shale and erosional removal of part of the upper Marcellus Shale. Additionally, the erosional boundary becomes more predominate as it extends towards the southwest. The average first 12 months of gas production from the Marcellus Shale indicates a larger quantity produced within Doddridge County (~1,300,00 mcf) in comparison to Ritchie County (~270,000 mcf). Production values can be a direct correlation to erosional features and thinning trends credited to the Taghanic unconformity.