Pore-Scale Study of Buoyancy-Driven Gas Bubble Migration, Breakup, Trapping, and Coalescence in the Near Injection Region of Liquid Saturated Porous Media
Zhihao Zhang, Rui Wu, Changying Zhao
Abstract
The injection of gases into liquid-saturated porous media is of great interest not only to the scientific research but also to the practical applications. The dynamics of the gas–liquid two-phase flow in porous media depends on the fate of the injected gas bubble near the injection point, that is, the so-called near injection region. The fate of the injected gas bubble on the other hand is affected by the microstructure of porous media. In this work, a pore scale study is performed to shed light on the buoyancy-driven gas bubble migration, breakup, trapping, and coalescence in the near injection region of the vertically placed pore networks at the low gas injection rate. Two types of pore networks with two extreme aspect ratios, that is, the pore throat to pore body ratios, are employed. In the pore network with the pore bodies having the same sizes as the pore throats, the gas bubble breakup occurs at the injection point, and the period between two successive bubble breakups is a power function of the injection rate. In the pore network with the pore bodies much larger than the pore throats, the bubble breakup occurs mainly in the pore throats, and the Bond number and the corner film flow-based capillary number control the bubble breakup in the pore throats and the bubble coalescence in the pore bodies. Our pore-scale study provides insights into understanding the dynamics of the buoyancy-driven gas bubble flow in the liquid-saturated porous media of different aspect ratios.