عنوان مقاله [English]
This study aims to investigate the effect of faults on the geochemical characters of the Asmari and the Bangestan reservoir oils in the Zeloi Oilfield. Plots of DBT/Ph versus Pr/Ph, C29/C27Strane20R versus Pr/Ph and Pr/(Pr+Ph) versus C27Dia/(Dia+Reg) indicate that oils of these reservoirs are generated from a single source rock, comprising carbonate-marl to marine shale lithology deposited under reducing marine environment with normal salinity. Moreover, plots of various biomarker ratios such as C29Strane20S/(20S+20R) versus C29Straneββ/(αα+ββ) indicate that oils in both the Asmari and Bangestan reservoirs have a similar maturity level. In addition, the diagrams of δ13C versus Pr/Ph, Oleanan index values and the standard diagram of C28Strane percent illustrate that the source rock for these reservoirs belong to the Upper Cretaceous to Early Tertiary age. The geochemical differences between the Asmari oil of the Zeloi Oilfield and the equivalent horizons in the surrounding fields, further, supports the connection of these reservoirs. Underground Contour maps (UGC) as well as the seismic profile indicate two faults that lead to the placement of the Pabde formation against the Bangestan reservoir in this oilfield. These faults could have acted as an open conduit for the movement of the oil generated from the Pabdeh Formation into the Bangestan reservoir. Furthermore, these faults can be considered as open pathways connecting the Bangestan reservoir with the Asmari reservoir, subsequently changing their geochemical characters through mixing. This study confirms the role of faults in creating change in the geochemical properties of various horizons in Zeloi oilfield.