裂隙水岩反应特征与雷诺数对溶解速率的影响

Characteristics of Water-Rock Reaction and Effect of Reynolds Number on Dissolution Rate for Fractures

以中国首个地下大型水封油库——黄岛油库为依托,在不同雷诺数条件下进行花岗岩单裂隙水岩相互作用试验,分析花岗岩单裂隙水岩反应特征和雷诺数对花岗岩表面可溶矿物溶解速率的影响.研究结果表明,在酸性条件下花岗岩发生化学反应的主要矿物为榍石;水岩之间发生的最主要化学反应为CaTiSiO5+4H^+→TiO2++H4SiO4+Ca^2+,H2O+CO2■HCO3^-+H^+和TiO^2++2H2O→H2TiO3↓+2H^+;0~10 d内水岩化学反应最强烈,随后逐渐降低,直至达到平衡;流体流动能显著提升榍石的溶解速率,相比Re=2500工况,Re=500工况下流体流动对榍石溶解速率的影响更大,这是由于较高的流速降低了溶质运移速率,使得宏观化学反应速率降低.

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+Ca^2+,H2O+CO2■HCO3^-+H+and TiO2^++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.