Perpustakaan Digital ITB

Carbon Capture and Storage (CCS) can be integrated with Enhance Coal Bed Methane (ECBM) recovery process by injecting CO2 into coal seam. Generally, flow gas transport in coalbed methane can be described in three stages. First, gas from the fracture which is produced while dewatering process causes the change of pressure gradient. While the gas is being produced, the gas from the matrix is starting to be desorbed because of concentration gradient. As the consequence, diffusion gas flows exists between matriks and fracture, then the accumulated gas flows through the cleats to the well. According to Ozdemir, 2004, flow geometry in coal seams can be represented by either rectangular or cylindrical. This study derived mathematical models in cylindrical porous media using momentum and mass balances after dewatering process of coalbed methane. Flow which is simulated in fractures/cleats only comprises methane and carbon dioxide that obey Darcy’s Law. Mass accumulation from coal matrices caused by diffusion is also considered in the fracture flow. Gas behaviour follows real gas law. Representative models of Mechanism on Enhanced Coal Bed Methane (ECBM) while injecting Carbon Dioxide (CO2) can be built using mathematical model in flexPDE version 5. Flow phenomena inside coalbed methane reservoir depends on Darcy Law and diffusion (Fick’s Law). In 10-year simulation, methane recovery for reservoir permeability 5 mD is 35.66%, methane recovery for reservoir permeability 8 mD is 49.35%, methane recovery for reservoir permeability 10 mD is 61.43%, methane recovery for reservoir permeability 25 mD is 77.23%, and methane recovery for reservoir permeability 50 mD is 76.87 %. Methane recovery for pressure gradient 2 MPa is 11.93%, methane recovery for pressure gradient 3 MPa is 24.50%, methane recovery for pressure gradient 4 MPa is 26.63%, and methane recovery for pressure gradient 4.6 MPa (base case) is 35.66%. Injection pressure and production pressure did not give an important effect on methane recovery, but the pressure difference did. Methane recovery for base case (reservoir thickness 55 m), methane recovery is 35.66%. Methane recovery for each reservoir thickness 10 m and 20 m are 87.96% and 81.88%. Methane recovery for base case (injection spacing 110 m), methane recovery is 35.66%. Methane recovery for injection spacing 55 m and 30 m are 78.41% and 80.11%. Some researcher found that methane recovery on ECBM process was mostly affected by engineering design, such as well pattern, well location, gas injection concentration, and injection pressure (above or below carbon dioxide critical pressure) for best carbon sequestration integration. Therefore, further study that optimize the best engineering design is needed to be done.