GAS DISTRIBUTION ENHANCEMENT IN KAJI-SEMOGA FIELDS, SOUTH SUMATRA, INDONESIA

摘要

In the near future, production of natural gas will become the star performer for PT Medco E&P Indonesia. In all Medco's working areas gas production is on the increase and gas is being supplied to several users for different uses, such as PLTG (Pembangkit Listrik Tenaga Gas), LPG (Liquefied Petroleum Gas) extraction plant, fertilizer plant, methanol plant, and possibly later an LNG plant if we achieve more than 1 TCF (trillion cubic feet) gas reserves. This is in line with the company's vision and mission to increase revenue and to maintain a good company image within the community.rnIn Kaji-Semoga, a Medco onshore oilfield in South Sumatera, nowadays about 60 mmscfd of gas is distributed daily. Gas is utilized in artificial lift (gas lift gas, up to 40 mmscfd), pressure maintenance (gas injection gas, up to 5 mmscfd), power generation (fuel gas for power plants, up to 7 mmscfd), and by consumers such as PLTG Talang Duku (up to 4 mmscfd) and Kaji LPG Extraction Plant (up to 4 mmscfd). Gas is separated from produced liquid at three stations: Kaji Station, Semoga Station, and Kaji Satellite.rnThe main components of the gas distribution system are compressors, control valves, measuring equipment, and pipelines. Gas is pressurized at compressor plants and then transferred using pipelines to each supply point. Control valves and measuring equipment are used to maintain and monitor the supply and demand situation based on a priority list: the most important priorities in Kaji-Semoga are fuel gas, gas lift gas, PLTG Talang Duku, Kaji LPG Extraction Plant, and gas injection gas.rnThe amount of produced and circulated gas is getting smaller by nature, but the requirement for gas isrnincreasing. Several construction projects associated with gas distribution and compressor operation have been carried out in Kaji-Semoga Fields since the middle of 2003, and are still on-going in the year to come. Based on the above requirements, challenges in gas management will become more complex and should be comprehensively taken into consideration when planning future operations.rnIn January 2004, 17.5 mmscfd, or more than 30% of produced gas, was flared in Kaji-Semoga Fields, even though some of the gas was already sold to PLTG Talang Duku (Figure 1). At the same time, the gas distribution system was often disturbed by a high occurrence of compressor downtime. Implementation of the company's no-flare policy (since 2003) and increasing demand of gas operation reliability has led to some modification projects to be carried out. The first modification was separation of a gas lift distribution system (originally centralized in the Kaji Field only) into two systems: a high pressure system to supply gas lift for the Semoga Field and a low pressure system to supply gas lift for the Kaji Field. Although separated, the two systems still back each other up.rnThe Kaji LPG Extraction Plant started to operate in the beginning of second quarter of 2004. This plant can take up to 20 mmscfd of rich gas and convert 5 mmscfd of it to 150 ton/day LPG. A side product of the LPG Extraction Plant is lean gas which is very suitable for fuel gas. The addition of the LPG Extraction Plant in the system has changed the gas distribution scenario a bit. Some of lean gas was transferred to internal power plants for fuel and the rest is sold to PLTG Talang Duku.