Publications

PT. Medco E&P Rimau have put efforts to improve fuel gas quality as several gas engine breakdowns occurred in 2012 in Kaji and Semoga Fields. As per fuel gas properties and power generation downtime data analysis, it is indicated that low methane number is one of the key causes. By definition, “Methane Number is the parameter used to quantify knocking tendency of a gas, especially relevant when natural gas is used as engines fuel” (A.M. Gutierrez, 2006). The minimum methane number for those related engines in the Kaji and Semoga Fields is 30 in order to avoid engine detonation. Two different methods to resolve the problems, Joule-Thomson (JT) and membrane processes have been evaluated and the result showed that the JT process is technically and economically more recommended to be applied due to its simplicity in installation, operation and maintenance. In mid-2013, Fuel Gas Conditioning Unit (FGCU) with JT process is installed at the Semoga Field by utilizing some idle equipment on site and also using in-house pipe-in-pipe heat exchanger. Previously, the fuel gas conditioning is only pressure reducing by using two pressure control valve in series. Installation of the so called “in house FGCU” successfully increases the methane number from 23.5 to 33.8, which also leads to the decrease in downtime caused by engine detonation. Besides the achievement on the methane number, this in-house pipe-in-pipe heat exchanger method also saves 60% of CAPEX and reduces approximately 6 months of overall project time compared to external parties/EPC work execution. Referring to the experience of the successful result in the Semoga Field, currently a similar method will be applied in the Kaji Field with several modifications, such as improvement on heat exchanger and instrumentation control design to optimize heat transfer and addition of hydrate inhibitor. Keywords: FGCU, low cost