are we there yet, page-13

East Gumai =The South Palembang Sub-Basin is part of the productive South Sumatra Basin, a back-arc basin formed by the interaction between the Indo-Australian and Eurasian Plates in Pre-Tertiary and Early Tertiary time.

The general Tertiary stratigraphy of the Palembang Sub-Basin from oldest to youngest unit is as follows: Lahat Formation, Talangakar Formation, Baturaja Formation, Gumai Formation, Airbenakat Formation, Muaraenim Formation, and Kasai Formation.

The Lahat Formation contains mature source rocks and is thought to generate gas in the Gunungkemala area. The Talangakar and Baturaja Formations contain source rocks which are rich in sapropel Type I & II kerogen. Both formations are mature. Gumai Formation contains mature humic Type III kerogen. The Airbenakat Formation has fair to good potential, but it is immature. The Muaraenim Formation contains much organic matter but is also immature.

The first migration of hydrocarbons in the Palembang Sub-Basin occurred in the Middle Miocene or at the end of Gumai Formation time. Early trapped hydrocarbons were redistributed into new traps following the Plio-Pleistocene orogeny.