PETERS, KEN E.1, TOM H. FRASER2, WELLY AMRIS3, BUDI RUSTANTO4, and EDDY HERMANTO4
1Mobil Technology Company, Dallas
TX
2Resource System Diagnostics
3Mobil Oil
Indonesia
4Pertamina, Jakarta, Indonesia
Abstract: Tertiary and Mesozoic Crude Oils in Eastern Indonesia
High-resolution geochemistry for 27 eastern Indonesian crude oils shows that 74% originated from Tertiary marine carbonate/marl source rocks, while only 19% and 7% came from Triassic-Jurassic marine carbonate or clastic sources, respectively. Most Tertiary and Triassic-Jurassic oils in the study occur north and south of 2°S latitude, respectively.
Low-sulfur Wiriagar oil (Irian Jaya) is highly mature. It originated from Type II/III kerogen in a Jurassic marine clastic source rock, possibly the Kembelangan Formation (Inanwatan Polysequence). Five sulfur-rich, low API-gravity oils from Oseil, Bula, AGL13S5, KS-90-16, and East Nief in the Bula Basin (Seram) originated from Type II kerogen in a Jurassic or older, anoxic marine carbonate source rock, like that on Buru Island. Similar syn rift-post rift carbonates and shales occur in the Inanwatan Polysequence in the Bintuni Basin and the Dingo Formation in Australia. The low-sulfur Aliambata oil from eastern Timor originated from Type II/III kerogen in a shaly equivalent of the above carbonate source rock deposited under oxic conditions.
Twenty other oils contain oleanane and originated from Tertiary marine carbonate/marl source rocks. Oils from Point Patrindo (Seram), Matoa, Minihaki, Kolo, Tiaka (Sulawesi), Southwest O (Salawati), Linda, Klamono, Klalin, Cendrawasih, Jaya, Kasim, Kasim Barat, and Walio fields (Salawati Basin, Irian Jaya) originated from Type II/III kerogen deposited under nearshore oxic conditions like that in Upper Miocene Klasafet source rocks.
AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas