Experimental study and modelling on diffusion coefficient of CO2 in water

One of the important ways to capture CO2 is to inject it into the (sub) surface water. This study focuses on laboratory measurements and modelling to find diffusion coefficient of CO2 into water and obtain dissolution rate during CO2 injection/flooding in the reservoir. Experiments were conducted in a precisionist Sanchez PVT-cell. Effective parameters on the diffusion coefficient were studied including temperature, injection pressure, and phase alteration of carbon dioxide. Diffusive transfers at pressures up to 18533 kPa and temperature range of 298 K-353 K were observed. The results revealed that at constant pressure of 5800 kPa, diffusion coefficient of carbon dioxide in water increases with increasing temperature. Likewise, at constant temperature of 298 K and 323 K, diffusion coefficient raised with growth of injection pressure. In addition, consideration of carbon dioxide phase alteration from gas to supercritical illustrated substantial drop of diffusion coefficient. Meanwhile, pressure decay method for finding the diffusion coefficient was modified which led to significant reduction of experiment duration and more accuracy of results by omitting source of errors. (C) 2020 Published by Elsevier B.V.