Modeling of Ex-Situ Dissolution for Geologic Sequestration of Carbon Dioxide in Aquifers.

Underground carbon dioxide ($CO_2$) sequestration is considered one of the main methods to mitigate greenhouse gas (GHG) emissions. In this technology, pure $CO_2$ is injected into an underground geological formation and since it is less dense than residual fluids, there is always a risk of leakage to the surface. To increase security of underground $CO_2$ disposal, ex-situ dissolution can be implemented. When $CO_2$ is dissolved in brine before injection, it significantly reduces the risks of leakage. In this approach, pure $CO_2$ is dissolved on the surface before injection. Surface dissolution could be achieved in a pipeline operating under the pressure of a target aquifer into which the $CO_2$ is injected. In a pipeline, $CO_2$ droplets are dissolved in brine during turbulent co-current two phase flow. In this paper, a comprehensive model of droplet dissolution along a pipeline is presented. The model accounts for droplet breakup and coalescence processes and is validated against available experimental data.