Geochemical fingerprinting of hydrocarbon sources using oil-to-oil correlation: Petroleum system evolution in the surghar range, Upper Indus Basin

Abstract

This study focusses on the biomarkers and non-biomarkers analysis performed on different crude oils samples representing three oil fields (Mela, Chanda and Nashpa), from Upper Indus Basin. Various physicochemical & analytical techniques have been employed. Full suite of n-alkanes, high ratio of saturates/aromatics, high American Petroleum Institute (API) gravity, low isoprenoid/n-alkane ratio and low sulfur specify typical light non-biodegraded crude oil. Low sulfur (<1 %) and high pr/ph ratio (1.88–3.7) suggest that the depositional environments of marine organic matter (OM) are typically oxic in nature. The relative distributions of C₂₇–C₂₈–C₂₉ ααα-20R steranes, C₁₉ and C₂₃ tricyclic terpanes (TT) along with Pr/nC₁₇ against Ph/nC₁₈ plot suggests that the crude oils mainly consist of marine OM likely from algal origin. These crude oils are sourced from the mature OM as evidenced from the isomerization ratios of C₂₉ steranes, C₃₂22S/(22S + 22R) homohopanes and carbon preference index. Aromatic biomarkers DBT/P and MPI indicate OM as oxic and mature source of hydrocarbons. The findings of this study enhanced the exploration strategies by identifying the light crude oil characteristics and OM origins, facilitating targeted drilling and extraction efforts in the region. Since the bulk geochemical properties and maturity of Mela, Chanda and Nashpa oil fields are alike, it can be concluded that oil within the reservoirs are quite similar indicating common source rocks.