Abstract: Based on the first large-scale underground water-sealed oil storage facility in China， viz Huangdao underground oil storage facility， the experiments of water-rock interaction in single fractures of granite at different flow rates were performed. The characteristics of water-rock reaction were observed and the effects of Reynolds number on the dissolution rate of soluble minerals on the surface of granite were analyzed. The results show that the main mineral of the chemical reactions of granite in acidic conditions is sphene. The dominant chemical reaction between water and rock are CaTiSiO₅+4H⁺→TiO²⁺+H₄SiO₄+Ca²⁺， H₂O+CO₂HCO^-₃+H⁺ and TiO⁺₂+2H₂O→H₂TiO₃↓+2H⁺. The chemical reaction rate is the highest in the first 10 days， then gradually decreases until equilibrium states are reached. Fluid flow can significantly increase the dissolution rate of sphene， however， the reaction rate in the experiment with Reynolds number of 500 is higher than that with Reynolds number of 2500， due to higher flow rate reducing the transport rate of solute， making the macro chemical reaction rate lower.

Key words: granite, single fracture, water-rock chemical reactions, Reynolds number, dissolution rate