Non-Hysteretic Capillary Pressure in Multiphase Flow in Porous Media: An Experimental Investigation Using 2D Porous Micromodels

Abstract:

Multiphase flow in porous media occurs naturally in many industrial and environmental systems. Understanding the fundamental flow physics in such systems is essential for many real-life applications. Among others, capillary pressure is an important parameter for multiphase flow in porous media, which was traditionally modeled only as a function of saturation and the relationship in turn was found to be hysteretic. Extensive research has been going on for decades to investigate and mitigate the hysteresis in capillary pressure-saturation curves. Recently it has been theoretically shown that a unique relation is possible with the inclusion of a few additional variables such as interfacial area, interfacial curvature and Euler characteristic in the functional form. It is also suggested that such a functional form would work for both equilibrium and non-equilibrium conditions. However, systematic and quantitative experimental investigations and validations of such a functional form are still lacking. To this end, capillary pressure along with saturation and other geometric variables are experimentally quantified for a multiphase flow in 2D micromodels. Fabricated 2D micromodel is a powerful tool to perform such studies as it offers excellent control over porous structures, great repeatability and excellent optical access. Employing fluorescence microscopy coupled with a high-speed camera, flow configurations as well as its dynamics are captured, which are then analyzed using advanced image processing algorithms. In this presentation I will be trying to delineate techniques for 2D micromodel fabrication and simultaneous measurements of capillary pressure, velocity field, interfacial area and Euler Characteristic, thus providing a general method for 2D micromodel validation of novel theories related to capillary pressure hysteresis. The results will provide new insight into the hysteretic behavior of capillary pressure as well as validations of new functional forms.