Geochemical Investigation, Oil-Oil Correlation of Sarvak Reservoir and Oil-Source Correlation of Ahmadi Member with Saturate and Aromatic Biomarker Data in an Oilfield from Southwest of Iran

Correlation of oils to each other and to their source rock is an important factor in defining a basin’s petroleum system. In this paper, 4 oil samples (#A13, #A09, #A04, #A03) from Sarvak reservoir and 2 source rocks (#SO1, #SO2) from Ahmadi member of Sarvak Formation in an oil field at southwest of Iran, were evaluated geochemically with Rock-Eval pyrolysis, column chromatography, gas chromatography (GC) and gas chromatography mass spectrometry (GC-MS) instruments. Moreover, thin section studies and Rock-Eval analysis along with biomarker data on source rock of Ahmadi member from Sarvak Formation indicate deep marine condition and kerogen type II. Determination of saturate, aromatic, resin and asphaltene fractions on study samples show paraffinic composition with nearly high thermal maturity for oils and naphtenic composition for extracted bitumen of probable source rock in studied oil fields. Geochemical studies indicate that the source rock of oil samples have carbonate-shale lithology in an anoxic marine environment. The biomarker ratios also show the medium to high thermal maturity of studied samples. Finally, star diagram of normal alkane and biomarker ratios, triangle diagram of C27-C28-C29 steran, variation of CPI, Pr/(Pr+Ph), C32 S/(S+R), C30 (βα/αβ+βα), C23 TT/C30 αβ Hopane and Tm/Ts versus calculated vitrinite reflex indicate that there are nearly biomarker similarities between #A03, #A04 and #A13 and source rock and can show genetic relationship. While #A09 oil sample with more space related to other samples might indicate more than one oil families in Sarvak reservoir of studied oil fields.