Geochemical and reservoir continuity assessment of Asmari and Bangestan reservoirs oils in Dehluran oilfield, North Dezful Embayment, SW Iran

In the present study, a total of 4 oil samples were systematically selected from the Asmari and Bangestan reservoirs in Dehluran Oilfield for geochemical evaluation of hydrocarbon system based on geochemistry and oil fingerprints analyses (GC, GC-MS, HRGC and Carbon Isotopes analysis). An investigation on distribution pattern of normal alkanes along with characteristic biomarkers of the depositional environment and sedimentary facies indicated that, source rock of the studied hydrocarbons was deposited in a reducing aquatic environment with low input of terrigenous material and dominantly carbonate lithology derived from organic algal matter. Also, the studied oil samples exhibited low- moderate maturity. The isotopic and biomarker results indicated that all the oil accumulated in both reservoirs has generated from same petroleum system with probable age of Jurrasic-Lower Creataceous. The application of branched and cyclic compounds in light hydrocarbons (C5 – C11) and pressure data to evaluate lateral continuity of the Bangestan reservoir confirmed the discontinuity of well located in NW of oilfield. These evidences could be related to presence of a seal fault or permeability barriers. Also, the reservoir geochemistry and petroleum engineering data proved good vertical reservoir continuity between the Asmari and Bangestan reservoirs.