Publications

Two major basins are found in the Natuna Sea: the West Natuna Basin and the East Natuna Basin. The Natuna Arch, a north-south trending basement high, separates the two basins. From well behavior observations there are indications of different pressure characteristics between the two basins although they have many apparent equivalent formations. There is very little indication of overpressure in the West Natuna Basin while the East Natuna Basin shows that significant overpressure is common. We conclude that overpressure in the East Natuna Basin is due to both disequilibrium compaction and unloading mechanisms. Disequilibrium compaction is the likely dominant mechanism in the East Natuna Basin due to rapid sedimentation since the Middle Eocene through Neogene as compared to the West Natuna Basin. Additional overpressure is attributed to unloading mechanisms due to thermal cracking of hydrocarbons as evidenced by the abundance of CO2 and high geothermal gradients in the basin. Keywords: Natuna Basin, Disequilibrium Compaction, Unloading Mechanism