The risk of CO2 leakage and the very slow rate of CO2 dissolution in brine present major technical challenges for secure implementation of CO2 sequestration at large scale in saline aquifers. To tackle these issues, a new technology based on Ex-Situ Dissolution Approach (ESDA) was developed recently aiming at dissolving CO2 in brine phase prior to injection into the aquifer to eliminate or minimize the risk of leakage and accelerate CO2 dissolution rate in brine. The ESDA is based on the mass transfer from CO2 droplets into brine in cocurrent pipeline flow. This paper presents mass transfer modeling associated with the ESDA process concerning the evolution of the droplet size and the pressure change along the pipeline. In addition, a technical and economic feasibility of the ESDA in comparison with the standard carbon capture and storage (CCS) technologies is presented. Various aspects such as CO2 displacement, geochemical reactions, CO2 leakage, pressure build-up, well spacing, and dissolution efficiency for the ESDA are also discussed. This study enables the evaluation of the ESDA process for CO2 sequestration through a systematic way.