Interplay of capillarity and reactivity at rock/fluid interfaces

Capillary behavior is observed in all facets of daily life including oil wicking in oil lamps, water absorbing in paper towels, movement of ink in fountain pens, siphoning beer from primary fermentation to secondary vessel, and drainage of the tear ducts in humans, and is a function of the channel openings, fluid composition, interfacial tension, and the contact angle at the fluid/solid interface. This behavior is also quite common in geologic media (e.g., damp rising in buildings, oil retention in rocks etc.) where it controls the distribution and transport of the fluid in porous media. In multiple such scenarios, the rocks and fluid might be chemically incompatible, i.e., it can induce mineral dissolution or precipitation, modify fluid composition through geochemical reaction, and/or alter pore structure and morphology, resulting in temporal evolution of the petrophysical properties of the porous media and the fluid's physical and chemical properties. This review makes the case of the impact of reactivity during capillary action at the rock/fluid interface. This is done by first detailing the mechanisms of capillarity including the fundamental physical principles and the models incorporating capillary imbibition, identifying the key parameters which impact capillary behavior in porous media. Then a few real-world cases are discussed where reactivity is occurring at the rock/fluid interfaces and the time-scale of reactivity and capillarity is discussed with the argument made for the importance of coupling reactivity and capillarity at such interface. Finally, the key limitations of the current approach are identified and the potential way forward is discussed.