Experimental Study of the Microscopic Visualization of Gas Clogging during Groundwater Recharge

Abstract

Clogging is one of the most important factors that restricts the development and popularization of artificial groundwater recharge technology. Gas clogging is an important but often overlooked form of clogging. In this study, a high-speed image acquisition system was used to obtain high-resolution images of the migration of water and gas in the pore. The bypass flow, trapped bubbles in the H-shaped pore channel, blind end, and corner of the pore were directly observed and their clogging mechanisms were analyzed. The influences of the pore structure and gas content on the degree of gas clogging were quantified. The pore–throat size has a certain controlling effect on the movement of the gas and liquid phases. As the diameter of the pore–throat increases, the clogging effect of the gas decreases, and the relative permeability of the water (krw) increases. The pore–throat ratio exhibits a negative correlation with the relative permeability of the liquid phase, and the pore–throat sorting coefficient exhibits a positive correlation with krw. As the gas content increases, the degree of gas clogging increases, and the effect is more significant at low gas-to-liquid ratios (<1:2). These results provide theoretical support for the scientific quantitative evaluation and prediction of the occurrence of gas clogging in groundwater recharge projects.