Analisa Komparatif Berbagai Metode Material Balance Untuk Estimasi Cadangan Coalbed Methane

Abstract

CBM (Coalbed Methane) is one of the promising unconventional hydrocarbons where gas reserves can reach 260 TSCF worldwide. The method to determine the amount of CBM reserves is by calculating the IGIP (Initial Gas In Place) which can be done by calculating the volumetric method or the performance method. One of the methods in this performance method is the material balance, where the calculation of the material balance in the CBM reservoir is not the same as the material balance in the conventional gas reservoir.

This thesis will show the research results of calculating various methods of material balance for the CBM field from synthesis data using reservoir simulation software CMG and Ms. Excel as calculation templates. There are 4 methods of material balance studied in this final project, namely the methods of Jansen and Smith, Clarkson and McGovern, Ahmed, and Mogadham. The simulation results show that the Jansen and Smith method has a large IGIP value with a value of 5509 MMSCF. The Mogadham method produces an IGIP of 1474.1366 MMSCF, Clarkson produces an IGIP of 3473.21 MMSCF and the Ahmed method produces an IGIP in the range of 122 MMSCF. This can happen because it is associated with the influence of parameter changes in IGIP calculations such as free gas storage, water & gas expansion, Langmuir isotherm model, gas volume formation factor, residual fluid and water influx.