Gas Bubble Nucleation and Migration in Soils—Pore-Network Model Simulation

Abstract

Sediment can be de-saturated by introducing gas bubbles, which is found in various applications such as methane gas generation in landfill, microbial-induced gas bubble formation, air sparing method for soil remediation, heavy oil depressurization for carbon recovery, and gas production from hydrate bearing sediment. The gas introduction method (e.g., nucleation and injection) and migration and trapping of gas bubbles affect the hydraulic conductivity, residual gas saturation, and the stability of these gassy sediments. In this study, the pore-network model is used to investigate gas bubble migration in porous media. Gas bubbles are introduced by mimicking either nucleation or injection. Based on the known gas bubble behavior available in the literature, numerical algorithms are developed to simulate the migration and trapping of gas bubbles in pore-network model. The effect of gas bubble size distribution and pore size distribution on residual saturation is investigated. The results show that gas bubble size distribution becomes wider as gas bubbles coalesce to each other during migration. And the residual gas saturation increase with increasing bubble size and permeability reduction becomes apparent as the gas bubble size and the number of generated gas bubble increase.