Source rocks study and thermal modelling in Salawati basin, West Papua

Hydrocarbon in Salawati Basin is generated from Tertiary and Pre-Tertiary source rock. Several source rocks studies have been conducted, such as in Sirga, Kais and Klasafet Formation. Lack of knowledge in characteristics and thermal modelling source rock in Sirga and Pre-Faumai Formation, also curiosity to observe basin reverse polarity occurrence is intriguing to be researched further. The purposes of this research are to know: a.) Sirga and Pre-Faumai Formation source rock characteristics to generate hydrocarbon in Salawati Basin; b.) Maturity values based on %Ro, Tmax and 1D basin modelling. Research methodology was carried out using petroleum geochemistry analysis, including: TOC, Rock Eval Pyrolysis, kerogen typing, vitrinite reflectance from 9 cutting samples. Based on TOC parameter, organic-rich materials in both formations show good to very good quantity. On the other hand, PY parameter shows fair to good potency quality as source rock to generate hydrocarbon. Kerogen type composition dominated NFA which indicates oxidizing marine or lacustrine depositional environment. Sirga and Pre-Faumai Formation show low level maturity based on %Ro and Tmax. On the contrary, based on 1D basin modelling maturity of the source rock on Warir-1X well and WIR-1A (outside research area) show higher level maturity (early to mid-mature) since Middle Pliocene and progressed into late maturity stage on oil generation since Early Pleistocene. Basin polarity reversal occurred since Pliocene and changed basin configuration i.e. depocenter from on southern area becoming on northern area. Sirga and the Pre-Faumai Formation are believed to be the two formations as hydrocarbon generating source rocks in the Salawati Basin based on geochemical characteristics analysis. Maturity based on% Ro shows the level of immature to peak mature.