Diamondoids as Indicators of Thermal Evolution and Natural Cracking of Oils From the Western Desert and the Nile Delta-Egypt

摘要

Thirty crude oil and condensate samples from offshore Nile Delta and Northwestern Desert of Egypt were analyzed to assess thermal maturity, extent of oil cracking, oil mixing characteristics, and oil biodegradation based on combined quantitative diamondoid analysis and biomarker data. The results indicate different extents of oil cracking and thermal histories. The Nile Delta samples have low biomarker (stigmastane) and high diamondoid (methyldiamantanes) concentrations, which is a sign that thermally cracked hydrocarbons are present. In contrast, the Western Desert oils generally have the opposite properties, suggesting they have not experienced cracking. Several of the analyzed samples appear to be a mixed accumulation of cracked and noncracked oil.