Maturation patterns of the Cambrian Rogersville Shale in the Rome Trough of Eastern Kentucky and West Virginia

Abstract

The Rome Trough of Eastern Kentucky and West Virginia records the failed rift of a larger Cambrian extension event along the modern day eastern and southern margins of North America. Rifting began in the Early to Middle Cambrian during the deposition of the Rome Formation and continued into the deposition of the Conasauga group. The Upper Rome and Conasauga together reflect a series of transgressive shale and highstand carbonate sequences. These formations have been tested for conventional hydrocarbon traps numerous times over the last forty years. While shows occur in multiple zones, these wells have yielded little in the way of economic discoveries, with few notable exceptions. Recently, there has been a shift to focus on the source beds as potential horizontal well targets.

The Middle Cambrian section of the Rome Trough contains multiple source beds within the Conasauga group. These occur in the transgressive shales of the Pumpkin Valley, Rogersville, and Nolichucky Formations. The Rogersville has become the primary focus of recent efforts as previous studies have shown this formation to contain the highest amounts of total organic carbon (1-5% TOC), and studies on produced oils have been typed back to bitumen within the formation. Burial history models for many of the existing Rome penetrations have given insight into the tectonic and thermal development of the Rome Trough and show a large amount of variability in the maturation and expected hydrocarbon phase. These models rely on present day stratigraphy, lithology, temperature, and maturity of individual wells combined with regional conditions such as uplift, erosion, and heat flow. These 1-D models have been applied within a sequence stratigraphic framework and then tied to an existing 2D seismic framework. After making calculations allowing for the decompaction of the section, a 3D burial history model results, showing where source rocks cross thermal maturation windows both spatially and temporally. The resulting maps allow the interpreter to determine the timing of generation, migration, and fault movement. Further, they provide meaningful interpolation into areas where well control and production are limited and allow for predictions of the amount and type of hydrocarbons generated and producible.

AAPG Datapages/Search and Discovery Article #90258 © 2016 AAPG Eastern Section Meeting, Lexington, Kentucky, September 25-27, 2016