不同有机酸对矿物溶解的动力学实验研究

用石英、微斜长石和方解石混合颗粒模拟碎屑组分分别与不同有机酸水溶液进行溶蚀实验，以比较储集层内不同矿物在含低分子量有机酸地层水中溶解的速率，并试图探讨矿物溶蚀的微观机理。结果表明：①所有矿物颗粒都发生了不同程度的溶解，表现为颗粒失重，溶液中SiO2和金属阳离子含量增加，pH值上升。②优先溶解的是方解石，其次是硅酸盐矿物。③温度增加，硅酸盐矿物在水中的溶解度明显增加，而方解石的溶解度基本不变。④由于不同有机酸与二氧化硅和金属阳离子生成的络合物稳定性不同，因此，在不同有机酸水溶液中，矿物的溶蚀速率有较大差别。多官能团有机酸的水溶液中，不同矿物有更大的溶解；但在含有丰富Ca2＋的草酸水溶液中，由于矿物颗粒表面难溶草酸钙的沉淀，方解石的溶解变得更加困难。⑤多官能团有机酸与SiO2形成的多环螯合物由于完全取代了硅氧四面体的氧原子，在水中具有高度稳定性，可能有助于(铝)硅酸盐的溶蚀和硅元素的迁移

Experimental research on dissolution dynamics of main minerals in several aqueous organic acid solutions

An experiment on mixed mineral grains of quarts,plagioclase and calcite dissolved in several aqueous organic acid solutions was carried out.The purpose of the paper was to compare the dissolving rate of the minerals in formation water containing abundant low-molecular organic acids under reservoir condition and to probe the microcosmic mechanism of corrosion.The results indicated that all mineral grains were eroded more or less after the experiment;it exhibited that the weight of grain decreased,whereas the concentration of SiO2 and several metallic cations and pH in aqueous solution increased.Solubility of calcite was prior to that of silicate;the solubility of silicate increased obviously with the increase of experimental temperature whereas calcite remained.The fact that stability difference of different complexes formed by SiO2 and metallic cations results in the distinct difference of dissolving rates of minerals in different organic acids.Minerals were more easily dissolved in polyfunctional organic solution than in oxalic solution containing abundant Ca2 .Precipitation of insoluble calcium oxalate on the surface of mineral grains worsens dissolution of calcite.Polycyclic chelates formed by polyfunctional organic acid and SiO2 have a high degree of stability in aqueous solution due to their substitution for oxygen atoms in the silicon-oxygen tetrahedrons,and which would be conducive to the dissolving of alumino silicate and and migrating of silicon in solution.