RELIABILITY OF 18a (H) OLEANANE BIOMARKER AS AGE INDICATOR OF SOURCE DEPOSITION

This study aims to evaluate the reliability of 18a(H)-01eanane biomarker as
an age indicator of source deposition. The problem arises when a tertiary reservoir
oil contains tertiary biomarker 18a(H)-01eanane to justify the source of oil.
Reliability of oil-source correlation using biomarker is dependable only when the
specific biomarker is not age equivalent of the reservoir. Oil in Tertiary reservoirs
cannot be confirmed by Tertiary biomarkers as generated from Tertiary source
because of the possibility of contamination. 18a(H)-01eanane as an age indicator
of source deposition has been tested here and the results show this specific
biomarker can be introduced in the oil as contamination if the reservoir holds
18a(H)-01eanane biomarker in pore waters in the pre-migration condition. Thus it
is concluded that although Oleanane is restricted within Late Cretaceous to
Tertiary periods, the presence of this biomarker in oils of Late Cretaceous to
Tertiary reservoirs cannot justify the age of the source of oil. This inference may
be universally true for all the biomarkers that need to be confirmed by using other
biomarkers.