Biomarker Characterization of Oil Seepages in Tomori Basin, Center of Sulawesi, Indonesia Muhammad Sulhuzair BURHANUDDIN(a), Asri JAYA(a), Adi MAULANA(a)
a. Geological Department of Engineering Faculty, Hasanuddin University, Indonesia
Tomori Basin is one of the basins which have many hydrocarbon potentials. This basin located nearby Banggai Basin which have several productive oil field. Therefore, hydrocarbon characterization of the Tomori Basin is a very interesting topic since the Tomori basin has several hydrocarbon potentials with the discovery of several oil seepages in the Tomori Basin area. This study would conduct an identification oil seepage characterization from Tomori Basin using a biomarker analysis approach. Oil seepages found in the Wosu Area and Kolo Area would be the main objective of this study. Determination of Oil seepage characteristics conducted using Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry method. This method would generate biomarker data for identification of organic matter origin, oxic and anoxic condition, source facies, or depositional environment of organic matter.
Based on the analysis Gas Chromatography (GC) of isoprenoid, the Pristane C19/Phytane C20 ratio of Wosu Oil shows a Pr/Ph value ratio of 0,75 as an indication of the anoxic condition typically from the hypersaline environment. Kolo Oil showing Pr/Ph ratio 3.37 indicated terrestrial organic input under oxic conditions. Cross plot between Pristane/nC17with Pr/Ph ratio showing Wosu Oil indicated derived from a highly anoxic environment with algae/bacterial organic matter input whereas the Kolo Oil derived from a suboxic-oxic environment with Pr/Ph value ratio 3,37 which indicated domination of organic matter input. Gas Chromatography-Mass Spectrometry was carried out in Wosu and Kolo Oil sample to determine the organic matter depositional environment pattern from both oil samples. Trycyclic terpene analysis from C19 to C25 shows Wosu Oil seepages tend to originate by mixing of terrestrial and marine organic matter or transitional environment. Based on the Biomarker Characteristics, Wosu Oil originated from organic matter of hypersalineenvironment in anoxic condition.
Keywords: biomarker, source rock, oil seepage,gas chromatography, Tomori Basin.