Ostwald ripening of gas bubbles in porous media: Impact of pore geometry and spatial bubble distribution

Abstract

We study pore-scale gas bubble ripening in porous media by combining a mass transfer method based on chemical potential differences with a level-set method for updating the gas/liquid configurations. We examine the impact of pore geometry and initial gas bubble distribution on the evolution, as well as the effect of mesh refinement and numerical parameters controlling the adaptive time steps in the model. Our results show that the pore geometry has a significant impact as it determines the rate of bubble pressure change with volume, while the area for mass transfer influences the time scale of the evolution. Simulations with different spatial patterns of bubbles with high and low pressures yield different ripening behaviors, classified as local and global ripening regimes. Simulations on sandstone with volumetrically similar bubble distributions display different ripening paths depending on the initial bubble locations, emphasizing the importance of capturing displacement history before ripening investigations.