The Warukin Formation – An Alternative Source Rock in The Barito Basin



A comprehensive geochemical study was performed on the Barito Basin. Approaches of standard geochemical analyses, Fluorescence Alteration Multiple Marcerals (FAMM) and computerize basin modeling have been used in this study. Sources quality and quantity for the Warukin Formation span widely from good to excellent. Very good ,hydrocarbon potential with some of these can be classified as excellent Type IF oil prone kerogens have been observed in some coal and carbonaceous shale beds within the study area. Results of vitrinite reflectance vary from 0.3 to 0.68% Ro indicating the deeper section in the well would be fully mature. All vitrinite reflectance data appear to indicate slightly suppression in all cases and a calibrating thermal regime has been attempted. Geochemically distinctive crude oil samples suggests the present of, at least, four oil groups, coincidently, appearing to be some stratigraphic discrimination. Two depocentres have been defined, namely Tapian and Bangkau Computerized basin modeling was attempt in order to model profiles of thermal maturation within the depocentres. Oil generation window in the Tapian Deep occurs at about 2900 m, whilst the Bangkau Deep seems to be shallower at about 2250 m. Onset oil generation occurred at approximately 4 Ma in the Bangkau Depocentre and somewhat earlier at about 6 Ma in the Tapian Deep, due to possibly an early activity of Meratus orogeny. Volumes of expelled hydrocarbons were calculated for each deep area and potential charge to each depocentre was estimated. Volumes of hydrocarbons are generally small (<10% generated oil from the Warukin source rock) due to low temperature in the formation. Only the deeper parts have expelled significant volumes of hydrocarbons. The total amount of expelled hydrocarbons is assumed that about 2.015 MMBO has been released from both Depoccntres. Keywords: Barito Basin, Warukin Formation, Geochemistry, Modeling, thermal maturity, FAMM, oil, biomarker.

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Authors : Haposan Napitopulu & Imam B. Sosrowidjojo