Exploration in Mature basin in Sumatra Island, Indonesia: A Historical Review to Challenge New Idea

Darwis, Avicenia¹, Sunjaya Saputra¹, Drianto Sudarmawan² (1) BPMIGAS (Indonesia), Jakarta, Indonesia (2) BPMIGAS, Jakarta, Indonesia

In the last decades, explorations in Sumatra are still very active compare to another area in Indonesia. There are 3 producing basin and 3 non producing basin in Sumatra. Based on exploration activity, Sumatra basin can be grouped into several category, which are : 1) the most active basin (more than 150 exploration well)-represents by South Sumatra Basin with technical success ratio around 42%, 2) Active basin (50-150 exploration well)-represents by Central Sumatra Basin with technical success ratio 52%, 3) Less active basin (10-50 exploration well)-represents by North Sumatra Basin with technical success ratio 0% 4) not active basin (less than 10 exploration well)–represents by Non Producing basin in Sumatra Region. Until now the North Sumatra Basin has discovered 5,352 MMBOE from 62 fields with most of the discoveries are gas discovery, Central Sumatra Basin has discovered 30,143 MMBOE from 199 fields, meanwhile in South Sumatra Basin has discovered 12,112 MMBOE from 189 fields.

There are rapid changes in exploration strategy in Sumatra provoked by several significant discovery in the last decade started with giant discovery of Kaji-Semoga Field by Exspan Nusantara in 1995-1996. Then there are 80 wildcat discoveries in all Sumatra Basin with the biggest well discovery located in South Sumatra Basin, meanwhile in North Sumatra Basin there is no discovery at all. Generally, the play concept has moved to the deeper target and older ages. The proven new play concepts include: Miocene syn-rift Talang Akar sands and Baturaja carbonates; Synrift of Menggala-Pematang in Central Sumatra Basin and Pre-Tertiary fractured basement rocks of South Sumatra Basin.