Publications

Biomarkers are organic chemical compounds whose structure or skeleton of carbon, hydrogen and other elements are formed by living organisms and are sufficiently stable to be recognized in crude oil or in the organic matter of ancient sediments. Biomarkers are also called molecular fossils, indicating formerly living organisms that developed in specific geologic environments. Development of paleogeographic settings and depositional environments was driven by tectonics. Source rocks with some specific biomarkers were deposited within these depositional environments/ source facies. Oils generated from organic matter of the source rocks contain biomarkers that are specific for depositional environments. Therefore, the oil biomarkers can be used to prove the existence of paleogeographic sites / depositional environments formed by tectonics. This means that oil biomarkers, indirectly, can be used to examine models of tectonics. Three cases of how oil biomarkers can be used to examine tectonic models are discussed in this paper. Firstly, in Western Indonesia, Paleogene rifted basins of Sumatra that were developed due to stress release of the Sumatran Fault relating to tectonic escape of post-collision India to Eurasia in Eocene time, are examined using oil biomarkers to understand the development of source facies formed duringrifting. Secondly, in Central Indonesia, biomarkers from recently discovered Eocene oils in the deep Makassar Straits and oil seeps in Western Sulawesi onshore are employed to examine the model of the Makassar Straits opening. Finally, in Eastern Indonesia, the Salawati Basin underwent tectonic reversal of its depocenter before and after the advent of the Sorong Fault tectonism in Mio-Pliocene time, and is examined by oil biomarkers from fields charged by Kais/Klasafet sources. The right understanding of tectonic models is important for determining an appropriate exploration strategy. Therefore, confirmed tectonic models, in this case using biomarker methods, are also important. The area of priority, objectives of exploration drilling, petroleum system analysis and well location selection can be better evaluated based on confirmed tectonic models.