Optimization of carbon dioxide dissolution in an injection tubing for geologic sequestration in aquifers

Dissolution of liquefied carbon dioxide in a turbulent tubing flow for geologic sequestration in aquifers is simulated. The problem is solved by a two-fluid approach in a three dimensional formulation. For accurate calculation of the droplet dissolution rate, an evolution of droplet size distribution along a tubing is modelled by the population balance equation accounting for droplet breakup, coalescence and interphase mass transfer. The dissolution rate in a horizontal tubing is rather slow due to gravity-induced droplet stratification. The dissolution process in a horizontal tubing is compared with that in a coiled tubing wound on a horizontal reel. In a coiled tubing flow, droplet stratification significantly decreases due to the gravity force causing periodical motion of droplets across the tubing. At relatively high flow velocities, CO2 droplets are well-dispersed even across a horizontal tubing. Droplet dissolution is rather fast in this case, and a notable difference in the dissolution rates in straight and coiled tubing is not observed. An effect of the flow rate on the dissolution process at different tubing diameters is illustrated. Thus, numerical studies show that a coiled tubing can be efficiently used for intensification of liquefied carbon dioxide dissolution for relatively low and moderate flow rates. • Dissolution of CO 2 droplets in a tubing flow in 3-D formulation is modelled. • Dissolution rate in horizontal tubing flow is low due to droplet stratification. • Using coiled tubing wound on a reel strongly enhances dissolution rate. • 3-D simulations allow optimal selection of coiled tubing parameters.