Dynamic Effects in Multiphase Flow: A Pore-scale Network Approach

Abstract

Current theories of multiphase flow rely on capillary pressure and saturation relationships that are commonly measured under static conditions. To incorporate transient behaviour, new multiphase flow theories have been proposed. These include an extended capillary pressure-saturation relationship that is valid under dynamic conditions. In this relationship, the difference between the two fluid pressures is called dynamic capillary pressure, and is assumed to be a function of saturation and its time rate of change. The dependency is through a so-called damping coefficient. In this work, this proportionality between capillary pressure and saturation rate of change is investigated using a pore-scale network model. It consist of a three-dimensional network of tubes (pore throats) connected to each other by pore bodies. The pore bodies are spheres and pore throats are cylinders. Numerical experiments are performed wherein typical experimental procedures for both static and dynamic measurements of capillary pressure-saturation curves are simulated. The value of the damping coefficient is determined for one realisation of our network model. Then, the effect of different averaging domains on capillary pressure-saturation curves is investigated.