Real-rock microfluidic platform for quantifying chemical dissolution and mechanical erosion in a multiphase environment

Fluid-rock interactions involving chemical dissolution, mechanical erosion, and multiphase flow are central to a wide range of geological and engineering processes, yet they remain poorly understood due to the lack of integrated <i>in situ</i> observation tools. Existing methods often compromise between spatial resolution and temporal dynamics. Here, we develop a real-rock microfluidic platform that enables simultaneous visualization and quantification of erosion dynamics in multiphase reactive systems. The platform integrates fluorescence microscopy, micro-particle image velocimetry, and ion chromatography to monitor the coupled evolution of solid-liquid-gas interfaces and flow velocity fields at micrometer-scale resolution. Microfluidic chips fabricated directly from limestone preserve natural mineral heterogeneity, and the platform enables direct observation of rock surface evolution and multiphase flow behavior. This facilitates decoupled analysis of chemical dissolution and mechanical erosion-two processes often difficult to isolate in traditional systems. Using this system, we investigate erosion during acid-rock interactions and identify a transition between two regimes-transport-limited and reaction-limited-controlled by CO₂ bubble mobility. In the transport-limited regime, immobile bubbles confine flow to thin films, enhancing dissolution and particle detachment. In the reaction-limited regime, surface-adhered bubbles shield reactive areas and reduce shear stress, suppressing erosion. We derive scaling laws that distinguish chemical and mechanical erosion rates and validate a theoretical model for the critical Péclet number marking the regime transition. This study advances understanding of erosion under multiphase flow and introduces a versatile experimental framework for probing pore-scale reactive transport. The platform can be extended to other rock types and fluids, offering a powerful tool for studying geochemical, physical, and biological processes in complex subsurface environments.