Publications

Lower Kutei basin experienced high sedimentation rates during Miocene time to recent. The Mahakam Petroleum Province represents the most prolific part of Kutei basin in hydrocarbon resources and shows a several kilometers thick first order sedimentary prism prograding eastward to the Makassar Strait. Five structural trends oriented north-south are recognized in this prism. Horizontal reflectors made up by 4000 – 5000 m of deltaic, fluvial and shallow marine deposits and clinoform reflectors constituted by 3000 – 4000 m thick slope and deep basin deposits can be distinguished in seismic sections. Four depocenter belts, parallel with the shoreline and shelf break lines, are recognized in the sedimentary prism. They are genetically related to pulses of prograding deltaic deposits organized in second order Genetic Sequences. The oldest depocenter is limited at its top by the 11 Ma maximum flooding. It represents the 2nd order Genetic Sequence recorded onshore from Batu Putih carbonate at 15 Ma to the carbonate in Pallaran section at 11 Ma. The following depocenter, limited at the bottom by the 11 Ma maximum flooding and the 7 Ma maximum flooding at the top, shifted 20-25 km eastwards. It is related to the 2nd order Genetic Sequence of Tunu Main Zone in the median axis. The third depocenter shifted around 20 km eastwards and is limited by the 7 Ma maximum flooding at the bottom and by the 5 Ma maximum flooding at the top. This interval represents the 2nd order Genetic Sequence of the Fresh Water Sands Formation. It is the main hydrocarbon producing interval of Sisi-Nubi field. The last depocenter is made up by sediments deposited above the 5 Ma maximum flooding to recent. It constitutes the last 2nd order Genetic Sequence of the Mahakam sedimentary prism. Second order cycles are made up by 3rd order Genetic Sequences, constituted in their turn by individual deltaic and fluvial cycles.