Effects of aqueous solubility and diffusion of multi-components on shale reservoir recovery during CO2 EOR

Abstract

The purpose of this study is to investigate effects of aqueous solubility and aqueous phase molecular diffusion of gaseous components when CO2 Huff and Puff process is applied into shale reservoirs. The gaseous components of CO2 and CH4 have solubility in water. In addition, flow of the CO2 and CH4 in shale reservoir is also affected by aqueous phase molecular diffusion phenemonon. Therefore, this study simulates CO2 Huff and Puff in shale gas-condensate and shale oil reservoirs considering the aqueous solubility and aqueous phase molecular diffusion of CO2 and CH4. The aqueous solubility during CO2 Huff and Puff increases the CO2 storage capacity in shale reservoirs, but provides negligible change on production. However, aqueous phase diffusion phenomenon of CO2 increases contacting area between CO2 and oil in matrix and enhances the production of CO2 Huff and Puff in shale oil reservoir. To be significant in the simulations of CO2 Huff and Puff, considering mechanisms of aqueous solubility and aqueous phase molecular diffusion is necessary in shale reservoirs.