Effects of Seam Conditions, Injection Pressure, and Gas Composition on CO₂ Sequestration in Coal

Carbon dioxide (CO₂) sequestration in deep coal seams has been identified as one of the potential methods to reduce CO₂ emission into the atmosphere. In this paper, a commercial coalbed methane reservoir simulator, COMET 3, was used to study the effects of seam conditions such as temperature and moisture content of the coal, and injection pressure and gas composition on CO₂ sequestration in coal. A 500x500x20 m coal layer, which is lying 1000m below the ground surface, was simulated in the model. CO₂ was injected from the bottom center of the coal layer for 10 years using a well of 0.1 m diameter. Four scenarios were simulated by changing the temperature and moisture content of the coal seam, and injection pressure and gas composition. The model results show that the amount of CO₂ that can be injected into the coal seam decreases by around 75% when the temperature of the coal seam changes from 10 °C to 50 °C; decreases by 99% when the moisture content of the coal seam was changed from 0.1 (cm³/cm³) to 0.5 (cm³/cm³); and increases by around 40000% when the gas injection pressure increases from 10 to 20 MPa, and increases by 80% when the percentage of CH₄ in the injection gas changes from 0% to 10%.