Organic properties and hydrocarbon generation potential of shales from few sedimentary basins of India

Abstract

Shales form the principal source rock for most of the conventional and unconventional petroleum systems. In India, both the prolific and prospective sedimentary basins have excellent to fair development of shales that range in age from the Proterozoic to Cenozoic. Deposition, preservation and maturation of organic content in shales define the source rock characteristics and its hydrocarbon generation potential, leading to a prolific/non prolific oil and gas play. Useful insight on development and hydrocarbon generation potential of shales and other organic rich source rocks is obtained through the geochemical study of sedimentary organic matter. In the present work, organic richness, kerogen type and thermal maturity of potential shales from few sedimentary basin of India, namely—Vindhyan, Krishna-Godavari, Kutch, Cambay and Jammu and Kashmir have been studied, to understand their effectiveness as source rocks in the particular basins. The studied shales show high Total organic carbon (TOC) content and contain dominantly Type III kerogen with partial contributions from Type II, in varying stages of hydrocarbon generation from immature to post mature, depending upon the thermal history of respective basins. Quantitative approaches involving the use of kinetic parameters for thermal cracking of organic matter (kerogen) into hydrocarbons, in conjunction with the source rock quality can account for improved understanding of the hydrocarbon resources in these basins.