Thermal modeling and organic geochemical appraisal of petroleum source rocks within the Aghajari Oilfield, SW Iran

Abstract

Dezful embayment contains several potential source rocks deposited in tectonically active environments. Existence of various source rocks with different geological ages makes this area one of the most prolific regions throughout the Middle East. The Pabdeh Formation (Lower Paleocene-Eocene), the Gurpi Formation (Santonian-Masstrichtian), the Kazhdumi Formation (Albian) and the Gadvan Formation (Neocomian-Aptian) are among the most favorable source rocks within the embayment. In this study the set of above mentioned source rocks are subject to pyrolysis in Aghajari Oilfield. Results reveal that the Kazhdumi Formation with highest TOC (4.43%) in compare to other probable source rocks has higher hydrocarbon generative potential and is the likeliest source rock responsible for the Asmari and Bangestan reservoirs in the Aghajari Oilfield. Moreover, the pyrolysis of Pabdeh, Gurpi and Gadvan formations show that they are of minor importance as potential source rocks within the studied Oilfield. The burial and thermal history of the Kazhdumi Formation was modeled to infer about the probable time of the hydrocarbon generation. According to Burial history profile and thermal modeling the beginning of the oil window for Kazhdumi Formation was dated at 13Ma. Moreover, the depth of oil expulsion is around 3800m in 9 Ma years ago.