Source rock properties and pore structural framework of the gas-prone Lower Permian shales in the Jharia basin, India

Abstract

This paper examines the source rock potential and pore structural framework of Lower Permian shales belonging to Barren Measures and Barakar Formations of Jharia basin, eastern India. The Jharia basin contains prolific coking-coal reserves and, consequently, the organic-matter in this basin tends to be mature. Open system pyrolysis analysis reveals that the Barakar Formation shales are thermally more mature and organic-rich than the Barren Measures Formation. Analysis reveals that shales of the Barren Measures possess “fair” to “good” oil generation potential. The more mature shales of the Barakar Formation are gas prone. Detailed pore scale distribution and fractal metrics determined by low-pressure N2 gas adsorption are observed to be higher for the Barren Measures Formation than the more mature and organically rich Barakar Formation shales possibly due to the inability of N2 gas to access the ultrafine components of the complex pores in the Barakar Formation shales. Substantial concentration of pores, organic-rich character, and thermal maturity levels indicates that the studied horizons have unconventional source rock properties.