Development of Marginal Bentu Gas Field in Central Sumatra Basin



Nowadays, demands of energy especially electricity are increasing which also lead to increasing gas demand to substitute oil fuels. Therefore, state-owned electricity company, PLN tries to find gas sources which near to their power transmission network grid. Bentu Field is a marginal field found in year 1981, 2P reserve is only 14 BCF, but luckily the field is located near PLN’s power transmission. Gas type of the Bentu Field is biogenic with good gas quality. The field will be developed in 2013 and expected to deliver the first gas to buyer in April 2013 at 3 MMSCFD for about 6 years with pressure 300 psig at delivery point, Bentu Mini Gas Plant. This paper means to present regarding marginal Bentu Field development in term of sub-surface, surface facilities and economical aspect.
Biogenic gas layer in Bentu Field is from 40-50 feet thick of sand layer over Late Miocene to Pliocene of Binio Formation as well known as main objective of biogenic gas in Bentu PSC. The Binio Formation was deposited in coastal environment that reflects the onset of marine regression. The gas is trapped along NW-SE anticlinal system related to reverse fault.
Good gas quality is showed by composition of gas which has > 97% CH4 and 1% N2 with <1% of CO2 and H2S. Accordingly, it is suitable to build a simple Bentu Mini Gas Plant. The facility built to process gas from Bentu-1 & 2 wells where its gas is delivered to gas buyer with capacity up to 5 MMSCFD.
Bentu Field development project consists of three major activities; run completion for two existing wells, flow line installation, warehouse and Bentu Mini Gas Plant construction to support activities at Bentu Block. Required budget of the project is US$ 10.76 million. The project at base case scenario will get NPV (12.5%), US$ 3.15 million at gas price US$ 4.8/MMBTU with 3% escalation/year for six-year period.
With increasing gas demand leads to high gas price, the marginal gas field which was currently suspended could be economical developed in near future. It is a very good step to improve revenue of company and government as well.

Keyword : marginal, biogenic, economic


Authors : R. W. Yuwono, R. Siregar, A. Kurniawan, T. Prabowo, S. Djaelani, Y. Gautama