Evaluation of Hydrocarbon Source Rock Potential and Organic Geochemistry in North Arafura Shelf, Papua (Indonesia)

Abstract

The results of this study identified two potential source rock intervals of Permian age in the North Arafura Shelf area of Papua, Indonesia. The first potential source rock interval (SR-1) was identified at 3834.9 m to 3838.6 m depth within the Kola-1 well, which is believed to be good to very good potential source rock with TOC in the range of 2.94 to 3.4 wt %, S1 0.78 to 0.97 mg HC/g, and S2 5.63 to 9.5 mg HC/g. The source rock is composed of type II and III kerogens with HI in the range of 164 to 275 mg HC/gTOC and reached the maturation stage with Ro of 0.83 -0.86%, Tmax of 442 -444 o C, and Production Index (PI) of 0.09 -0.12. The second potential source rock interval (SR-2) is at 3060.1 -3136.3 m depth in the ASM-1X well and has fair potential to be source rock with TOC of 0.95 wt %, S1 of 1.01 mg HC/g, and S2 of 3.39 mg HC/g. This source rock has type II kerogen with a HI value of 357 mg HC/g TOC and has reached maturation as indicated by a Ro value of 0.63%, Tmax of 430 o C, and PI of 0.23. Biomarker analysis revealed SR-1 is type III kerogen with terrigenous input and was deposited in an estuarine environment.

Geochemical Characterizations of Crude Oils in Pendopo High and Limau Graben, South Sumatra Basin

“…The cross plot Pr/nC 17 -Ph/nC 18 (see Figure 5b) as proposed by Connan and Cassou (1980), shows that crude oil samples from Pendopo High and Limau Graben derived from humic kerogen, but in the Pendopo High they are more towards mixed kerogen (humic and sapropelic kerogen) (Sabra, 2021). The cross plot of carbon isotope δ 13 C saturates -aromatics as proposed by Sofer (1984), shows that crude oil samples from Pendopo High (Figure 6a) are mostly derived from alga, and the saturate fraction are heavier than crude oil samples from Limau Graben.…”

Aliphatic Biomarker Signatures of Crude Oil from Tarakan Subbasin, Tarakan Basin, North Kalimantan, Indonesia

“…The ratio of pristane and phytane and the distribution of n-alkanes can be used as environmental indicators of oil deposition (Al-Atta et al, 2014;Hakimi et al, 2016). Biomarker analysis had been applied to several source rocks, including Sydney Basin sediments (Ahmed et al, 2009), Niger Delta oil (Nytoft et al, 2014), Sinamar Formation, Muara Bungo, Jambi (Zajuli and Panggabean, 2014), Ordos Basin oil (Ji et al, 2016), North Arafura Shelf Papua (Sabra, 2021), and Eocene source rock in West Sulawesi (Sutadiwiria et al, 2022). The Tarakan Basin, which has entered the exploitation of drainage, requires an in-depth study of organic geochemistry to determine the depositional environment, its maturity, and the source of its organic material.…”