A Numerical Study of Dynamic Capillary Pressure Effect for Supercritical Carbon Dioxide-Water Flow in Porous Domain

摘要

Numerical simulations for core-scale capillary pressure (P°)-saturation (S) relationships have been conducted for a supercritical carbon dioxide-water system at temperatures between 35° C and 65°C at a domain pressure of 15 MPa as typically expected during geological sequestration of CO2. As the P°-S relationships depend on both S and time derivative of saturation (dS/dt) yielding what is known as the "dynamic capillary pressure effect" or simply "dynamic effect," this work specifically attempts to determine the significance of these effects for supercritical carbon dioxide-water flow in terms of a coefficient, namely dynamic coefficient (x). The coefficient establishes the speed at which capillary equilibrium for supercritical CO2 (scCO2)-water flow is reached. The simulations in this work involved the solution of the extended version of Darcy's law which represents the momentum balance for individual fluid phases in the system, the continuity equation for fluid mass balance, as well as additional correlations for determining the capillary pressure as a function of saturation, and the physical properties of the fluids as a function of temperature.