Geological Storage of CO2 Beneath the Southern Rocky Mountains-Colorado Plateau Region

The Southern Rocky Mountains-Colorado Plateau region presents unusual scientific opportunities for studying the effects of geological storage of CO2. An abundance of oil and natural gas fields, as well as natural CO2 fields, proves the existence of reservoirs and seals in the sediments that are suitable for long-term gas storage. The widespread occurrence of near-surface coal has resulted in large coal-fired power plants being collocated in the same region. The six largest power plant sites are point sources of 100 million tonnes/year of CO2, and four natural CO2 fields produce over 30 million tonnes/year mostly for enhanced oil recovery. Structures near to these power plants, as well as the produced natural CO2 fields could provide storage for significant volumes of CO2 separated from power plant flue gases. We report on the latest findings from a multi-disciplinary study using the natural CO2 fields as analogues for long term CO2 storage. The frequent presence of stacked reservoirs in these systems and obvious outflow of CO2-rich fluids in the vicinity of two known CO2 areas suggests that it is unrealistic to expect total containment of CO2. Local containment in a domal or stratigraphic trap may also not be a requirement for long-term storage. Dipping or undulating reservoir structures that are not laterally confined may actually be preferable because of the opportunity for long flow paths and a long time scale that promotes permanent sequestration of injected CO2, either as a mineral or dissolved in groundwater. Results of two-dimensional, two-phase reactive transport modeling of CO2 injection into a dipping sedimentary sequence beneath a large power plant in central Utah will be presented.