Microfluidic experimental study on clay particle migration and pore-throat clogging: Implications for hydrate-bearing clayey-silty sediments

Hydrate dissociation significantly changes pore water salinity and fluid flow conditions in clayey-silty sediments, triggering the migration of clay particles. However, previous studies have predominantly used spherical SiO2 particles as substitutes for clay minerals, leaving the migration and clogging behavior of actual clay particles, and its quantitative characterization, largely unresolved. In this study, microfluidic experiments were systematically conducted to investigate the migration and clogging behaviors of clay and SiO2 particles under various conditions, including different pore-particle diameter ratios, particle mass fractions, flow rates, gas–water ratios, and salinities. The results show that clay particles exhibit significantly lower critical clogging mass fractions (e.g., 0.2%–0.4% at a pore-throat diameter of 50 μm) than SiO2 particles (0.6%–1.0% under the same pore-throat diameter), indicating that SiO2-based proxies may systematically underestimate the risk of pore clogging. Moreover, clay-induced clogs demonstrate greater structural stability, whereas SiO2-induced clogs are prone to “clogging instability” under dynamic flow conditions. Mechanistic analysis reveals that clay migration is governed by electrostatic forces and salinity-dependent double-layer effects, whereas SiO2 migration is fluid-controlled. These quantitative findings provide a more accurate framework for predicting permeability damage in hydrate-bearing clayey-silty sediments.