Eight samples from the Gurpi Formation were selected in order to determine hydrocarbon generation potential and thermal maturity in the Nousoud water supply tunnel, Ezgeleh area, using Rock-Eval pyrolysis. The results indicate that the organic matters are mainly terrigenous and contain type III and II/III kerogen. The Gurpi Formation is thermally mature and most of the samples passed through oil window. Vitrinite reflection (RO) of the majority of the samples is between 1.3 and 1.5 which means the Gurpi Formation is a mature source rock, probably produced liquid hydrocarbon. According to HI and Tmax, the Gurpi Formation is potentially gas prone and could be classified as fair to good potential source rock. On organic facies diagram, this formation suggests CD facies type implying oxic to suboxic condition during the deposition of the Gurpi Formation which was deposited during LST. Results of X-Ray analysis indicate that the main component of the samples is calcite; quartz and pyrite are found in some samples. Kaolinite and illite were not observed in the studied samples.
