Publications

The South Aman trough (SAT) is one of the most prolific sub-basins in Central Sumatra. The proven excellent organic richness and source quality of the Brown Shale (a member of the Pematang Gp.) provides excellent sourcing to prospects located within or along the rim of troughs recognized within the Central Sumatra Basin. The latest discovery well in 2011 had confirmed the presence of a structure located within the main depocenter area of the South Aman trough. This structure is located in Rokan Block as a three-way dip closure anticline, bounded by a normal fault at its northern part. This paper is intended to share reservoir characteristic and development opportunity of this structure, based on conventional well logs, mud logs, 3D seismic data, well test, and laboratory analysis of fluid samples. Drilling result confirmed the presence of an active petroleum system in the KO area. The main productive reservoir is represented by the Upper Red Bed Formation, a fining to blocky upward sandstone unit. Testing results are showing that the reservoir has the capability to deliver as much as 2300 BOPD with 10% water cut. The reservoir boundary is defined by pressure transient analysis: this suggests that the reservoir boundary is within a radius of 250 m. Based on this observation, to optimize the recovery factor up to 35% of the OOIP, this field will be developed with several additional development wells. The fluid analysis is suggesting that all of the oil samples have the characteristics of a light crude oil with minor wax contents as generated from source rock material deposited in an oxic environment, such as shallow lacustrine or terrestrial. All these evidences confirmed that the Pematang Group, particularly Upper Red Bed Formation, has good reservoir quality in South Aman area. Keywords: Exploration, Field Development, Reservoir Characterization, Central Sumatra Basin.