Petroleum System Analysis Using Geochemical Studies, Isotope and 1D Basin Modeling in Hendijan Oil Field, SW Iran

Abstract

Hendijan oil field is located in north of Persian Gulf and is producing oil from 3 different reservoirs. Geochemical studies of candidate source rocks have revealed that four interval of source rocks exist in this region that could generate hydrocarbons. These formations include: Pabdeh (Tertiary), Kazhdumi (Albian), Garau (L. Certaceous) and Sargelu (M. Jurrasic). Oil-Source rock correlations are based chemical properties, biomarkers, C13 Isotope and other geochemical indices. Geochemical analyses done in Hendijan oil field have shown that Kazhdumi and Garau formations are the most important source rocks in the region. Pabdeh formation is excluded from possible source rocks due to its low maturity. No geochemical analyses have done on Sargelu formation. Different geochemical analyses including GC, GC-MS and Isotope (Carbon and Sulfur) have done on 3 oil samples from Asmari (Tertiary), Sarvak (M. Cretaceous) and Nahr Umr (E. Cretaceous) reservoirs. In addition, burial and thermal history modeling was performed to determine timing of hydrocarbon generation in the candidate source rocks in studied field. Geology and sequence Stratigraphy analysis of borehole data including drill-cuttings provided fundamental constrains for burial history reconstruction. One-dimensional model of thermal evolution were derived from the burial history and calibrated with Vitrinite reflectance, thermal conductivity, surface and bottom-hole temperature measurements, as well as with paleoclimate data. Regarding geochemical analysis on several oil samples, all the reservoirs have been charged by one source rock. Biomarkers and isotope data indicate that Kazhdumi Formation correlates best with oil samples. In addition to geochemical analysis, 1D petroleum system modeling shows that Kazhdumi and Garau source rocks reached oil generation window in 3 and 4 MY ago respectively and both of them are still in oil generation window. But lack of Oleanane biomarker in analyzed oil samples and low TOC content of Pabdeh formation confirms no charge of reservoirs by tertiary candidate source rock (Pabdeh).