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Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
An Integrated Approach Involving Biomarker and Isotope Data for Oil to Source Rock Correlation of Najmah and Sargelu Formations, North Kuwait
(1) Exploration - Studies Team, Kuwait Oil Company, Ahmadi, Kuwait.
The Najmah and Sargelu formations of Jurassic age are considered as potential source rocks in the State of Kuwait. A suite of samples consisting of 9 rock extracts from 3 wells in Dhabi, Mutriba and Raudhatain fields and 8 crude oil samples from 5 wells in Dhabi, Bahrah, Umm Niqa, NW Raudhatain and West Minagish in northern Kuwait selected as representative data to study to establish oil-source rocks relationships within Najmah and Sargelu formations in northern Kuwait.
A variety of geochemical parameters including normal alkanes, triterpanes (m/z 191), steranes (m/z 217), carbon isotopes, both saturated and aromatic, were employed as main component variables in the statistical approach. The multivariate analysis methods - “Hierarchical Cluster Analysis (HCA)” and “Principle Component Analysis (PCA)” have been adopted to make the process of evaluating correlation data more objective as well as to speed it up. A series of analytical and interpretation processes were conducted by measuring and selecting a number of accurate molecular (biomarker) and isotopic parameters.
The HCA technique employs 14 variables of geochemical data. These were grouped into 4 clusters of oil and rocks samples. The relationship among clusters on the dendogram confirmed high responses of similarity level. Bahrah and West Minagish crude oils were grouped into a common cluster at similarity level of 94.53, while Umm Niqa and Raudhatain crude oils grouped together in a different cluster having similarity level of 98.67. These Crude oil clusters and source rocks are connected by dendogram at similarity level of 81.28 providing significant evidence that crude oils were generated from Jurassic source rocks.
Continuance approach in PCA technique (14 variables) divided all the samples into three main quadrants. Crude oil samples from Bahrah, West Minagish, Umm Niqa and Raudhatain fall in quadrant-III and slightly different in Principle Component from its precursor of source rocks in quadrant-I. Alteration of the hydrocarbon fluids within reservoir are believed to be responsible for the variations of geochemical characteristics within oil samples.
It is concluded that integrated statistical techniques that utilize selective suite of sensitive geochemical variables in both biomarker and carbon isotope data are best suited for establishing oil-source rock relationships, classifying oil in genetic families, and also addressing problems of reservoir continuity.