Investigation of Hydrocarbon Generation Potential of Mobarak Formation by the Use of Pyrolysis Rock-eval2 Geochemical Method

In order to evaluate the hydrocarbon potentiality of Mobarak Formation in Mighan Section (situated in North-East Shahrood City), of East Alborz, 19 surface rock samples were collected for Rock-Eval-2 pyrolysis. The obtained Results indicated that the Mobarak Formation in Mighan section region has relatively high TOC, adequate Tmax values and with moderate hydrocarbon potentiality, have passed diagenesis stage. Plotting of Tmax values verses Hydrogen index (VanKrevelen diagram) for the given samples revealed that The Mobarak Formation in Mighan section has kerogen of type III with little amount of mixed type II/III kerogen. The organic matter of Mobarak Formation in the Mighan section with Tmax between 455-498°C has already crossed the oil window and has reached the wet gas generating stage. Based on OI and HI indices and distribution of samples on organic facies diagram, the majority of samples are belonging to CD and D groups region, indicating slightly an oxidized environment for Mobarak Formation. With respect to S2/S3 ratios, the upper horizons of Mobarak Formation contain has higher quality of organic matter in comparison to lower sediment layers. With increase of TOC contents, apparently input of organic matter with terrestrial origin with sedimentation fixed rate, has been prevailed in sedimentary basin.