Perpustakaan Digital ITB

Coalbed methane (CBM) is an unconventional natural gas resource stored primarily by adsorption on the internal surface of the coal matrix. Gas production from CBM reservoirs depends on the ability of the natural fracture system, known as cleats, to transmit fluid toward the wellbore. When cleat permeability is insufficient, hydraulic fracturing is commonly applied to improve reservoir connectivity and enhance production performance. This study develops a conceptual CBM reservoir simulation model using CMG GEM with three reservoir scenarios representing different cleat permeability conditions. For each scenario, a base case simulation without fracturing and a base fracture simulation are conducted to evaluate the effect of natural fracture permeability and hydraulic fracturing on gas production rate and recovery factor. A sensitivity analysis is then performed in CMOST to identify which hydraulic fracturing parameters have the most significant influence on the recovery factor. The results show that higher cleat permeability produces an earlier and higher peak gas rate, while lower cleat permeability results in a flatter and lower production profile. Hydraulic fracturing improves gas production rate and recovery factors across all three models, with the largest improvement observed in the low permeability model and diminishing returns as natural fracture permeability increases. The sensitivity analysis consistently identifies fracture width and fracture permeability as the two dominant parameters across all three reservoir models. These results indicate that fracture conductivity, jointly controlled by fracture width and fracture permeability, is the primary determinant of recovery improvement in CBM reservoirs within the selected parameter ranges conducted in this study.