Portal de Periódicos da CAPES

The oleananes: Origin, maturation and limits of occurence in Southern Nigeria sedimentary basins

1988; Elsevier BV; Volume: 13; Issue: 1-3 Linguagem: Inglês

10.1016/0146-6380(88)90033-2

1873-5290

C.M. Ekweozor, Onkel Udo,

Petroleum Processing and Analysis

Oleananes occur within well-defined age and paleogeographic boundaries in the sedimentary province of Southern Nigeria thus signifying that the biomarkers may be analogous to index Fossils. In Anambra Syncline/Lower Benue Trough the biomarkers are found in rocks which are as old as late Upper Cretaceous. In Tertiary Niger Delta the concentration, composition and distribution of the oleananes in rocks and oils are determined mainly by palaeodepositional environment and thermal history and are independent of age and geographical location of specific samples. Oleanane content varies with increasing burial-depth with peak concentration coinciding within Rm% range, 0.4–0.6 implying early generation of hydrocarbons from the basin's typically resin-rich kerogens. It is evident that the oleanane content parameter is superior to the hopane and sterane isomerisation indices for monitoring thermal maturation in the delta and for differentiating paralic from paralic-marine source-facies as well as early from late generated oils.