Classifying rock dissolution patterns using reaction persistence length and front velocity

Atefeh Vafaie , Sam Krevor

Acid–rock dissolution in carbonates underpins many natural and engineered subsurface processes. Péclet–Damköhler (Pe–Da) scaling is traditionally used to relate dissolution patterns to reaction kinetics, advection, and diffusion, but it fails to explain contrasting patterns in fluid–rock systems with similar pH. This is because Da does not capture reaction-rate changes along the flow path, and the framework omits reaction capacity, which varies widely among fluid–mineral systems. Here we revisit this problem by retaining Pe to describe the advection–diffusion balance, replacing Da with a reactive persistence length (LE) representing the spatial extent of sustained reactivity, and introducing a reaction-front velocity (Vf) incorporating reaction capacity to describe front advance. Applying this framework to published experiments involving CO2-rich water, HCl, and EDTA injection into limestone and undersaturated brine injection into salt reveals a common progression of dissolution patterns in three-dimensional Pe–LE–Vf space despite chemical and mineralogical differences. These complementary physical measures capture both reactive-front advance and the spatial persistence of reactivity.