Vitrinite reflectance suppression in New Albany Shale, Illinois Basin; vitrinite reflectance and Rock-Eval data

Abstract

Modeling the thermal history of the Illinois basin, Illinois, Indiana, and Kentucky (Figure That is, measured Ro values (tables 1 and 3) are lower (less mature) than vitrinite reflectance equivalents based on other thermal maturity indicators. Observations indicated that the degree of thermal maturity in RQ profiles (constructed by extrapolating from the Middle Pennsylvanian (Desmoinesian) Herrin coal through the Upper Devonian-Lower Mississippian New Albany Shale) does not always increase with increasing depth of burial. In fact, the Ro of the Middle Pennsylvanian Herrin coal is similar, and in some instances greater than that of the Upper Devonian-Lower Mississippian New Albany Shale, yet the New Albany is up to several thousand feet deeper. The purpose of this report is to present new Ro (table Two Rock-Eval parameters, Tmax and hydrogen index, are compared with measured Ro data for several New Albany Shale samples from throughout the Illinois basin, and RO correction contours for the New Albany Shale are estimated (table 1 and Figure