Direct Imaging of Bubble Ripening in Two-dimensional Porous Media Micromodels

Abstract

Carbon geo-sequestration technology is expected to play a significant role to reduce anthropogenic emission and achieve negative emission in the long term. The subsurface storage potential of CO2 is largely dominated by capillary action that generates a so-called residual phase in the pores of the rock in the form of disconnected bubbles. Understanding the temporal and spatial evolution of this residual phase is key to ensure the long-term storage security of CO2. To understand the factors affecting the stability of residually trapped CO2, we make direct observations of the interactions of a population of air bubbles surrounded by undersaturated water in a regular 2D porous medium micromodel at isothermal conditions. Mass transfer between neighbouring bubbles is shown to start at ~10 times bulk diffusive time scale and to correlate with the capillary pressure gradient between bubbles.