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Geochemical Characteristics of Lacustrine Source Rock: An Insight of Banuwati Formation from Offshore Sunda and Asri Basins, Indonesia a) Doctoral Program in Geological Engineering, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung, Jl. Ganesha, 10, Bandung, 40132, Jawa Barat, Indonesia Abstract The Sunda and Asri Basins are petroliferous in Indonesia. Although the two basins have produced billions of barrels of oil equivalent since the beginning of their production, the study of source rock organic geochemistry on those basins is relatively limited, especially on the sapropelic kerogen of the syn-rift package of Banuwati Formation. The organic geochemistry study of the Banuwati Formation in Sunda and Asri Basins was determined in a comprehensive study based on kerogen and biomarker data. The data were obtained by using some techniques, including carbon analyzer, Rock-Eval pyrolysis, gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), and organic petrography analyses from five wells. The Banuwati Formation has good to very good source rock quality and quantity. The biomarker analysis reveals a new novelty interpretation that Banuwati shale source rock has been deposited in an oxic-suboxic setting. The Banuwati Formation dominantly consists of Type I organic material with some characteristics such as the presence of uncommon biomarkers, e.g. C26 tricyclic terpane and an indication of botryococcane peak which strongly indicates a lacustrine environment. In terms of maturity, there is a different result between Ro and Tmax. Tmax values indicate the formation is mature, but based on Ro it seems immature. This phenomenon was most likely due to Ro suppression that often happens in the Type I kerogen samples. Keywords: Source rock- Banuwati Formation- biomarker- lacustrine- Sunda and Asri Basins Topic: Interdisciplinary Geosciences |
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