Modeling of carbon dioxide dissolution in an injection well for geologic sequestration in aquifers

Abstract

Carbon dioxide (CO2) sequestration is considered to be one of the most effective technologies of mitigating greenhouse gas emissions. In this technology, single phase supercritical CO2 is injected into an underground geological formation such as a deep saline aquifer. Existing sequestration projects demonstrate that successful implementations are possible; however, signifi cant uncertainties associated with the risks of leakage remain an obstacle for broader use of this technology. The security of underground disposal could be considerably increased by dissolving the CO2 in a brine produced from the aquifer, then reinjecting the mixture underground. The dissolution process occurs before the mixture reaches the aquifer; this significantly reduces or completely eliminates the risks of CO2 leakage. This technique can drastically extend the amount of worldwide aquifers available for carbon sequestration. As was previously shown, complete dissolution could be achieved in a surface pipeline operating under the pressure of a target aquifer, where CO2 is injected. In this paper, a comprehensive model of CO2 droplet dissolution in a vertical injection well is presented. The model accounts for droplet breakup, coalescence, and dissolution processes as well as temperature and pressure variations over well depth. Feasibility and results are discussed and compared with surface dissolution options.