MMIJ Annual Meeting

The trapping of gas by capillary forces in the pore space is an essential process to increase capacity and ensure the safety of carbon dioxide storage. The capillary desaturation curve describes the change in residual saturation as a function of capillary number. However, the impact of grain geometry on the capillary desaturation curve has not been conceived yet. In this work, the unconsolidated porous media with three kinds of shapes were selected. Glass beads, silica sands and plastic particles represent spherical, moderated and highly angular grains, respectively. High-resolution micro-tomography was used to obtain the morphological characterization of residual gas inside porous media. The results indicate that under low flow rate (capillary forces controlled regime), the residual gas saturation is independent of capillary number. Higher volume of gas bubbles were trapped in porous media with angular particles than spherical particles. In addition, the bubble size distribution and interfacial area were also sensitive to the particle shape. When the capillary number increases above a critical value, the residual saturation decreases sharply for all kinds of packings. The grain geometry has a weaker effect on the capillary trapping during dynamic flow regime