Publications

Since the 1930s, the island of Buton which is located on the southeastern arm of Sulawesi has attracted people for the surfaced asphalt occurrences who are searching for proof of a working petroleum system. Field observation was conducted as a follow up to a previous publication by the author about the hydrocarbon potential in Buton which was sponsored by PT. Emas Hitam Energi.Double collision tectonic in Buton had obducted ophiolite rocks into so-called Kapantoreh Mt. This ophiolite is provenance of pebbly sandstones and conglomerates of Tondo Formation which is considered as Molassic sediment. These collisions also play role for the occurrence of surface asphalt deposits.The recent field work observed some hydrocarbon manifestation including: asphalt occurrences, oil stains, a hydrocarbon related water pool and probable source rocks in south Buton. Structural features such as faults, folds, and lineaments were also observed either from field observations or aided by the interpretation of satellite imagery. Some measured section of Miocene Tondo Formation, which is considered as promising reservoir rock, comprising of conglomerates and sandstones facies also made during field observation to give an insight about depositional system of Tondo clastics.Additional analysis such as rock-eval pyrolisis and gas chromatography were undertaken to assess pretertiary source rock potential and its geochemical parameter. Most of the source rocks are type-II kerogen derived from marine biota and thermally immature. Oil stain and asphaltic data show “hump which is an indicator of degraded hydrocarbon. The occurrence of tar/asphalt in well Sampolakosa-1S could be an indicator of immature source rock or merely degraded hydrocarbon due to fault as evidenced by repeat section along the well profile.Those observation results could give understanding about asphalt forming, reservoir prediction, probable source rocks, and prospect estimation in terms of plate tectonic. Some of the data, both geochemistry of oil stains and biostratigraphy are provided and published with permission from PT. Horizon Geoconsulting.