South Sumatra

Commentary

South Sumatra is mature, but recent large gas discoveries, revised Gross Split terms and improved PSC flexibility continue to attract investment. SKK Migas's status remains a watch point. Outlook: Positive.

Updated

October 12, 2026

Location

Description

The South Sumatra Basin, is a back-arc Tertiary basin that formed between the stable Sundaland micro-continent and the subduction zone between the northward moving Indian Plate and the stable Asian Plate. Two major tectonic events define the basin stratigraphy, an Eocene - Oligocene extensional event and the Late Miocene – Present Barisan orogenic event. The first resulted in the formation of numerous north-south orientated half-grabens and the second caused uplift of the Barisan Volcanic Arc to the west, and major compression and uplift within the basin. The former event provides the depositional setting for both source and reservoir horizons within the rift sequence and overlying thermal sag units, while the latter results in trap formation and also exerts a strong control on hydrocarbon generation and migration.

Summary

South Sumatra is considered a mature exploration area, with over 2,500mm bbl of oil and 9.5tcf of gas produced. However a recent large gas discovery in the Kali Berau Dalam-2 well in this basin, highlights that significant new reserve additions can still be made in these areas by the re-evaluation of the regional petroleum systems, both by identification of new plays or extension of plays to unexplored areas. As with many mature areas, the exploration and concession award history often results in successively more focused exploration programmes in smaller areas. This can lead to an increased emphasis on reservoir and trap delineation without further evaluation of the regional petroleum systems and, in particular, the hydrocarbon charge component.