Abstract

The Bengkulu forearc Basin which is commonly assumed to be unrewarding areas for hydrocarbon exploration is situated in the southeastern part of the Sumatra Island. The most extensive hydrocarbon exploration activities in the basin are mainly in the offshore areas focusing on Miocene carbonate buildups and Early Miocene basal sandstones. More recent exploration activities were targeting the lower two mega sequences of Paleocene to Early Miocene ages. Although past hydrocarbon explorations were focused in Miocene carbonate plays on the offshore areas, the Eocene to Oligo-Miocene mega sequences are very promising as shown by recent successful discoveries of two grabens.

Claystone of the Seblat Formation (Oligo-Miocene) are good potential source rocks for oil-prone kerogen. The maturation levels combined with possible catalytic effects of the clay minerals may to generate medium to light oils. The top of the oil window recorded in the Arwana-1 well is in the Late Oligocene Seblat Formation. Therefore, the poorly documented Eocene lacustrine sediments may have matured enough to generate hydrocarbons.

From recent reinterpretation of the regional structural framework as well as geochemical data, it is suggested that there will be further Paleogene oil discovery in the Bengkulu Basin since Paleogene oil accumulation has occurred in the Sumatra basins.