Evaluation of organic petrography and hydrocarbon potential of the Garau Formation in Aligudarz section, Lorestan

In order to evaluate the hydrocarbon potential of Garau Formation in Aligudarz section, organic petrography analysis and Rock Eval pyrolysis were performed on samples. In this research totally, 15 samples were studied by transmitted, reflected and fluorescence light and also 12 samples using Rock-Eval pyrolysis device. The existence of bituminite was detected in the transmitted light of amorphous organic matter group and their equivalent in reflected light. Also, the fluorescence of all samples was low, which indicates presence of type II kerogen in the Garau Formation. Since the paleo depositional environment of Garau Formation was pelagic (deep marine) with no terrestrial organic matter input so was no chances of existence of vitrinite macerals for reflectance analysis. Hence, in order to evaluate the thermal maturity, the parameter of thermal alteration index (TAI) and solid bitumen reflection (BRo%) were used, which indicate the early to middle stage of thermal maturity (oil window) of samples in the Garau Formation. According to the parameters obtained from Rock Eval pyrolysis and related diagrams, the quantity of organic matter in samples ranged from good to very good and in terms of quality, show type II and II / III kerogen. Finally, the calculated source potential index (SPI) in the studied section is 19.38 m ton / m2 which shows a high source potential index.