The economics of CO2 storage in coal seams with enhanced coalbed methane recovery (CO2-ECBM) - development of screening criteria

Carbon capture and storage is a greenhouse gas mitigation strategy that allows the continuous utilisation of fossil fuels while long-term zero or low emissions alternatives are being investigated and improved. Coal reservoirs have received attention as CO2 storage sinks as the injection of CO2 has the potential to enhance gas recovery. This thesis investigates the economic feasibility of CO2 storage in coal reservoirs in an Australian and a more general context. The objective is the identification of screening criteria for economic CO2 storage with incremental CBM recovery (Storage-ICBM) through the development of a methodology that integrates reservoir simulation with techno-economic modelling to assess the economics of CO2 storage, the identification of the reservoir properties to which the economics of Storage-ICBM are most sensitive, the establishment of preliminary operating guidelines, and probabilistic analyses to establish the conditions that provide CO2 storage in coal with the highest possibility of economic success.It is demonstrated that the application of Storage-ICBM can add more value to coal reservoirs that are less economic to start with, such as low permeability or undersaturated reservoirs, when gas and CO2 prices are high. However, the first commercial Storage-ICBM projects are expected to be those for which the threshold to economic viability is the lowest. The probability of an economic Storage-ICBM project using vertical wells is highest when the reservoir permeability is between 1 and 100 mD, the cumulative CO2 injected is between 30 and 100 Mt/100 km2, and the incremental recovery exceeds 2,000 Mm3/100 km2. Higher CO2 prices decrease the minimum requirements for reservoir permeability and gas content for economic Storage-ICBM while higher gas prices have the potential to increase the minimum requirements of these properties. Thus, higher gas prices will not necessarily lower the threshold for Storage-ICBM to become economically viable, but the presence of a CO2 price will. The results of this thesis deliver insight into the economics of CO2 storage in coal while presenting a starting point for screening for coal reservoirs that are likely candidates for economic CO2 storage