Interfacial Tension and Contact Angle Measurements for the Evaluation of CO_2-Brine Two-Phase Flow Characteristics in Porous Media

摘要

It is of great importance to investigate gas and water flow characteristics to better understand the geological CO_2 sequestration process. The interfacial tension between CO_2 and brine and the wettability of reservoir rocks are the most important parameters for two-phase flow in porous media that have a significant influence on the capacity of CO_2 storage. In this paper, we present a set of interfacial tension data between CO_2 and a sodium chloride (NaCl) solution and the contact angle data between CO_2, NaCl and quartz by using a visual experimental method at multiple pressure, temperature and salinity conditions. We also performed simulations of CO_2 and NaCl solution two-phase flow in quartz bead-packed beds by introducing interfacial tension and contact angle data into the pore network model to evaluate the relative permeability and capillary pressure. We found that the phase alternation of CO_2 from a gas to its supercritical state has a significant influence on the wettability of pore surfaces and thus governs the capillary trapping mechanism. This indicates that CO_2 sequestration efficiency in a saline aquifer will be greatly affected while CO_2 is in its different phase states. The simulation results showed that a pore network model is available for the study of CO_2 and brine two-phase flow characteristics in porous media.