Application of Light Hydrocarbon (C₇+) and Biomarker Analyses in Characterizing Oil from Wells in the North and North Central Sinai, Egypt

Abstract

Seven representative oil show samples from wells in the north and north central Sinai have been characterized by means of a variety of organic geochemical techniques (C₇ hydrocarbon and biomarker analyses), to illustrate origin, differences, and similarity among oils. These oils were obtained from Cretaceous and Jurassic reservoirs. The C₇ oil correlation star diagram (OCSD) suggests closely related oils, derived mainly from similar source rocks, while the C₇ oil transformation star diagram (OTSD) and C₇ light hydrocarbon analyses indicate a minor degree of transformation of some oils, as Misri-1, Halal-1, and Nakhl-1 oils were subjected to evaporative fractionation. Moreover, the studied oils show no sign of water washing and biodegradation. Molecular characteristics suggest pre-Tertiary shales and carbonate source rocks, deposited under a saline oxic environment, rich in terrigeneous organic sources with significant bacterial and algal input. Since the studied oils are of mixed marine and terrestrial origin, C₇ signature of these oils is not representative of their origin and should be supported by other geochemical evidence (e.g., biomarkers) to predict their origin.

Keywords:

• C₇ OCSD
• C₇ OTSD
• C₇+ and C₁₅+ hydrocarbons
• Sinai
• Egypt

ACKNOWLEDGMENT

The authors are grateful to the authorities of the Egyptian General Petroleum Corporation for providing the analyzed data and permitting publication of this work. They are grateful to Prof. Dr. Mahmoud Y. Zein El Din, Geology Department, Al Azhar University for critical reading and reviewing this work.

Notes

*P2 = 2-methylehexane.

**P3 = 2,2dimethylpentane+2,3-dimethylpentane+3,3-dimethylpentane+3-ethylpentane.