Experimental observations of fracture dissolution: The role of Peclet number on evolving aperture variability

Dissolution of the surfaces of rock fractures can cause significant alteration of the fracture void space (aperture) and fracture permeability ( k ). Both surface reaction rates and transport of reactants within the fracture can limit local dissolution. We investigated the role of Peclet number ( Pe ), a measure of the relative importance of advective and diffusive transport of reactants, on fracture dissolution in two identical transparent analog fractures with different initial values of Pe ( Pe o ). High‐resolution light‐transmission techniques provided direct measurements of the evolving aperture field during each experiment. For Pe o = 54 distinct dissolution channels formed, while for Pe o = 216 we measured minimal channeling and a reduction in short wavelength aperture variability. The nature of the dissolution patterns strongly influenced the relative increase in k . A 110% increase in the mean aperture due to dissolution resulted in estimated permeability increases of 440% and 640% for the Pe o = 54 and Pe o = 216 experiments, respectively.