Organic Geochemical Investigation of Crude oils from the Al Bayda Platform Area (Samah formation), Central Part of the Sirte Basin, Northern Libya

Abstract

In this paper, the geochemical studies of API gravity, content of asphaltenes and gross compositions were performed on samples from two crude oils collected in the Al Bayda Platform Area (Samah formation), central part of the Sirte Basin. The results showed that the fraction of saturates is the dominant fraction in oils in comparison to aromatics and NSO components, with high API gravity and low content of asphaltenes which indicates that the oils are mature, generated from marine organic sources and that they can be classified as light crude oils. The aim of this study is to provide evidence about precursor of organic material, depositional environment, and maturity of the studied oils. Saturated hydrocarbons were analyzed by gas chromatography – mass spectrometry and gas chromatography – mass spectrometry – mass spectrometry technique. Results indicates that the oil samples are originating from high marine organic matter phytoplankton and algae, with few terrestrial inputs, reflecting that oils can be sourced from siliciclastic, possibly marine shales deposited in a clay-rich marine, deposited under intermediate conditions with high maturity. All results showed that the oil samples are similar in their characteristics, likely due to the migration pathways in the same region.