عنوان مقاله [English]
During the drilling of Nousoud tunnel in the west of Kermanshah Province (Iran), much hydrocarbon seepages spilled from the fractures and walls of the tunnel. In order to evaluate and assess hydrocarbon source rock potentiality, a detailed geochemical study was carried out on Pabdeh, Gurpi and Ilam Formations in Nosoud tunnel and Garu Formation in Pataqe#1 and Imam Hassan#1 wells in the west of Kermanshah. A total of 22 cuttings and 9 core samples were subjected to geochemical investigations.
The result of the primary assessments using Rock-Eval pyrolysis technique, vitrinite reflectance measurements elemental, clay minerals, chemical analysis and molecular (biomarkers) studies (GC, GC-MS), showed that Pabdeh Formation (lithologically composed of marl and argillaceous limestone) has poor potential for hydrocarbon generation. Maturity of the studied formation is in the early phase of catagenesis and exhibits Types II and III kerogen. Pabdeh formation was deposited in marine anoxic environment. Whereas, Gurpi formation in Nosoud tunnel and Garu formation in Pataqe#1 and Imam Hasan#1 wells exhibit fair potential for hydrocarbon generation and their maturity is in the peak and late phase of catagenesis. These formations have mixed Type II and III kerogen which were deposited in marine anoxic environment and are lithologically composed of shale and argillaceous limestone. Having reservoir characteristics and carbonate lithology, Ilam formation doesnot seem to be a potential source rock (high measures of TPI & S1 plus worthless measures of S2). The findings of this study showed that Gurpi formation along the tunnel and Garu formation in more depths are good sources for hydrocarbon seepages in Nousoud tunnel and the neighboring areas.