Barito Basin is one of producing basins in Indonesia. It is located in Southeast Kalimantan along the southeastern edge of stable Sundaland continent. This basin has produced about more than 800 MM bbls of oil (in place) so far. It caused by certain petroleum system, which consist on elements (source rocks, reservoirs, cap rocks, trap) and process (maturity and migration). Some tectonic activities occur in this basin. The most dominant one is tertiary tectonic, which give some significant influence of hydrocarbon potencies, especially in petroleum system as seals and traps. The tectonic activity of this basin was started by rifting of the basement in Paleo-Eocene. The condition prevailed up to Oligo-Miocene during which localized and regional subsidence, lithospheric stretching, interrupted by uplifting, impressed the basin. This rifting produced a set of horst and grabens that were decisive for the compression and uplifting, has reactivated the old fault block rather than developed new structures (Satyana, 1993). Those tertiary tectonic activities sequences were implied on petroleum systems. Synrift sequence sediments were deposited in the Paleogene grabens as the transgression progressed northwest along the rift axes, hence alluvial channels and fan prograding into lacustrine environments, resulted in richness of source rock. Postrift sequence sands, are potential for reservoir rocks better than those deposited in synrift sequence. The Upper Tanjung marine shales were deposited across most of the basin also in postrift sequence as the transgression progressively submerged rift margin basin at the end of Eocene and Early Oligocene. Structural inversion were greatly affected the basin from Late Miocene to Pliocene time, and created anticlinal trap. Plio-Pleistocene inversion might formed new anticlinal structural traps as well as destroying previous hydrocarbon accumulation. This possibility could remigrated hydrocarbon to the newly formed anticlinal structure.
Author : Lolita Marheni, Reski Aditiyo, Alanta Elyan Putra, Esti Anggraeni