Stable carbon and sulfur isotope distributions of crude oil and source rock constituents from Burgan and Raudhatain oil fields (Kuwait)

Abstract

Seven crude oils and ten possible source rocks from Kuwait have been investigated for the stable carbon and sulfur isotopic compositions of chromatographic oil and extract fractions, asphaltenes, kerogen, carbonates and S-bearing minerals. The crudes are isotopically very similar and suggest a single organic source. They also show characteristics intermolecular isotopic distribution patterns.

On the basis of the criteria: organic richness [extractable organic matter-total organic carbon (EOM-TOC) relationships], carbon and sulfur isotopic similarities of oils, extracts, pyrite and kerogen, samples from the Ratawi Formation (Raudhatain oil field) and the Minagish Formation (Burgan oil field) showed indications of source potential. The excellent isotopic correlations with the sample from the Mauddud Formation (Raudhatain oil field) are explained by impregnation of rock samples by reservoir oil. In the core samples, an increase in the organic matter content is correlated with¹³C enrichment in the carbonates.

The results demonstrate the potential of stable carbon and sulfur isotope correlation methods in geochemical hydrocarbon exploration.