The economic feasibility of enhanced coalbed methane recovery using CO2 sequestration in the San Juan Basin

Carbon dioxide emissions are considered a major source of increased atmospheric CO2 levels leading towards global warming. CO2 sequestration in coal bed reservoirs is one technique that can reduce the concentration of CO2 in the air. In addition, due to the chemical and physical properties of carbon dioxide, CO2 sequestration is a potential option for substantially enhancing coal bed methane recovery (ECBM). The San Juan Fruitland coal has the most prolific coal seams in the United States. This basin was studied to investigate the potential of CO2 sequestration and ECBM. Primary recovery of methane is controversial ranging between 20-60% based on reservoir properties in coal bed reservoirs15. Using CO2 sequestration as a secondary recovery technique can enhance coal bed methane recovery up to 30%. Within the San Juan Basin, permeability ranges from 1 md to 100 md. The Fairway region is characterized with higher ranges of permeability and lower pressures. On the western outskirts of the basin, there is a transition zone characterized with lower ranges of permeability and higher pressures. Since the permeability is lower in the transition zone, it is uncertain whether this area is suitable for CO2 sequestration and if it can deliver enhanced coal bed methane recovery. The purpose of this research is to determine the economic feasibility of sequestering CO2 to enhance coal bed methane production in the transition zone of the San Juan Basin Fruitland coal seams. The goal of this research is two- fold. First, to determine whether there is a potential to enhance coal bed methane recovery by using CO2 injection in the transition zone of the San Juan Basin. The second goal is to identify the optimal design strategy and utilize a sensitivity analysis to determine whether CO2 sequestration/ECBM is economically feasible. Based on the results of my research, I found an optimal design strategy for four 160- acre spacing wells. With a high rate injection of CO2 for 10 years, the percentage of recovery can increase by 30% for methane production and it stores 10.5 BCF of CO2. The economic value of this project is $17.56 M and $19.07 M if carbon credits were granted at a price of $5.00/ton. If CO2 was not injected, the project would only give $15.55 M.