Source rock evaluation of Gondwana shales from Damodar valley, Eastern India: Implications for hydrocarbon Potential

In the present study, fifty-one Gondwana shale samples comprising Raniganj Formation, Barren Measures and Barakar Formations from the Damodar Valley, eastern India, were investigated through Rock eval pyrolysis to evaluate hydrocarbon potential source rocks. The Raniganj shales were characterized by excellent total organic carbon (TOC) content varying between 6.1 and 36.21wt. % and comprising of type II-III kerogen in thermally early mature to mature stage (T max range between 439 and 448 degrees C and VR 0 range between 0.74 and 0.90 %), which is appropriate for generating oil and oil/gas. The Barren Measures shale contains very good TOC between 3.43 and 7.1wt. %, marked by type III kerogen in well mature stage (T max between 446 and 451 degrees C ; VR 0 between 0.87 and 0.96) and thus can be categorized as high-grade source rock for potential hydrocarbon target. The Barakar shale were also characterized by excellent TOC (3.2 and 25.88wt. %) with type III kerogen in thermally mature to post-mature stage (T max between 464 degrees C and 483 degrees C ; VR 0 between 1.19 and 1.53) and thus categorized as high-grade source rock prone to generate extensively gaseous hydrocarbon. Barakar formation covers an extensive area (appx. 218 sq. kms) having thickness 800 m to 1250 m in the Jharia sub-basin. Shale beds in this formation with excellent TOC comprising type III kerogen in thermally mature to post mature stage, are depicted in this study. It is speculated that these source rocks can be promising target as future shale gas reservoir for shale gas exploration and exploitation.