Geochemical and physical properties of oils collected from several wells in the Shabwah depression, Yemen: implications of their characteristic organic matter input and maturity

• Published in: Arabian journal of geosciences Vol. 14; no. 23
• Main Authors: Hakimi, Mohammed Hail, Lashin, Aref A., Varfolomeev, Mikhail A., Abidin, Nor Syazwani Zainal, Saeed, Shadi A., Al-Muntaser, Ameen A.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.12.2021; Springer Nature B.V
• Subjects: Aliphatic hydrocarbons; Alkanes; Anoxia; Biomarkers; Composition; Crude oil; Earth and Environmental Science; Earth science; Earth Sciences; Environmental conditions; Environmental indicators; Geochemistry; Gravity; Indicators; Jurassic; Maturity; Organic matter; Original Paper; Oxidoreductions; Petroleum; Physical properties; Rocks; Sandstone; Saturated hydrocarbons; Sedimentary rocks; Shale; Shabwah depression; Biomarker; Geochemical correlation; C isotope; Crude oil; Yemen
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-021-08598-8

Four crude oil samples representing the Jurassic sandstone sequence were collected from several wells in the Shabwah depression and analyzed using conventional geochemical and physical methods. The results were used to evaluate the oil samples, focusing on the characteristics of their source rocks, including the origin of organic matter input, redox depositional conditions, and degree of thermal maturity. The observed physical results show that the examined oils are light crude oils owing to their high American Petroleum Institute (API) gravity of 35.0–40.1°. The high API gravity and aliphatic hydrocarbon fraction indicate that the examined oils were generated from mature source rocks. The biomarkers of n -alkane, isoprenoid, hopanoid, and steroid with the δ 13 C isotopic compositions suggest that the oil samples were sourced from clay-rich rocks containing mixed organic matter with high contributions of marine organic matter and deposited under suboxic to relatively anoxic environmental conditions. The biomarker maturity indicators also suggest that the oil samples were generated from mature source rocks. According to the biomarker environmental indicators and δ 13 C isotopic compositions, the oil samples are from the Late Jurassic Madbi shale source rock.