Application of Oil Fingerprinting and Biomarker Analysis to Study Fluid Connectivity and Reservoir Isolation and Genetic Typing of Oil Obtained from the Eastern Caspian Basin (Kazakhstan)

ABSTRACT In this paper was performed fingerprinting analysis 130 oils derived from 8 oil and gas fields in the Eastern part of Pre-Caspian basin (Laktybay, Karatobe, Karatobe South, Alibekmola, Kozhasay, Eastern Urikhtau, Akzhar Eastern, Bashenkol) for reservoir compartmentalization studies and prediction of petroleum migration pathways, while biomarker analysis of representative samples was carried out for genetic typing of oils. On the basis of the analysis performed on the area, several promising zones of hydrocarbon accumulation are identified for increasing hydrocarbon resources and reserves in the future. The results of this study showed that all studied oils of the Eastern Caspian Basin were generated from marine source rock. However, the oils of the pre-salt deposits (Kozhasay, Alibekmola, Urikhtau) were generated from carbonate source rock, while those of the post-salt deposits (Karatobe, Karatobe South) were from marine shaly ones, although within the two fields of post-salt deposits (Laktybay and Akzhar Eastern) occur oils derived from shaly and carbonate sources. Genetic typing of the studied oil samples, according to biomarker parameters, indicates the presence of two genetically different oils in Laktybay and Akzhar Eastern fields, associated with different generation sources - with source rocks of carbonate and shaly formations. According to the thermal maturity of oil from pre-salt deposits of carbonate origin (Alibekmola, Kozhasay, Eastern Urikhtau fields) showed relatively low thermal maturity in comparison with oil from post-salt deposits (Laktybay, Karatobe, Karatobe South, Akzhar Eastern).