Oil Families in the Eastern Mediterranean Offshore and Southern Israel: Biomarker and Trace Element Analysis
Oil samples were obtained from producing wells and DSTs from the eastern Mediterranean offshore and the southern coastal plain and Dead Sea area in Israel. The oil samples were fractionated by liquid chromatography and analyzed by capillary gas chromatography and gas chromatography-mass spectrometry to define their gross chemical and biomarker composition. The nickel and vanadium content of the samples was analyzed by emission spectrography.
The oils may be classified into three different families which agree with their geographical distribution. The biomarker distributions and nickel/vanadiam ratios of the oils from the Dead Sea region suggest they were derived from a carbonate-rich source rock deposited in a highly reducing hypersaline environment. The oils from the coastal plain Helez-Kokhav field were also generated from a predominantly carbonate-rich source rock. However, they probably were contributed from a clastic rock deposited in a slightly less reducing depositional environment, as indicated by the presence of diasteranes and higher pristane/phytane and nickel/vanadium ratios. The Ziv 1 oil from the eastern Mediterranean offshore was probably generated from a predominantly clastic, marine source rock.
All the oils analyzed seem to have been generated from mature source rocks. The maturity of their host rocks is much lower, indicating the oils reached their present location by lateral and/or vertical migration. The Dead Sea region oils have suffered varying amounts of water-washing and biodegradation, whereas the Helez-Kokhav and Ziv 1 oils have suffered limited water-washing and only little (if any) biodegradation.
AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.