酸化体系中石英的稳定性实验研究

利用X’Pert PRO X-射线衍射分析仪、分光光度仪等手段,系统评价了石英在60℃条件下,与5%HCl、5%HCl＋0.5%HF、5%HCl＋1.0%HF、0.5%HF、1.0%HF、8%HBF4和5%HCl＋7%HBF4七种常见酸体系反应的化学行为,重点分析了酸液中可溶硅离子浓度变化特征及影响因素。研究表明：石英与HF酸、土酸反应快速强烈,前2h硅离子浓度波动大,是硅质沉淀形成的主要时期;与氟硼酸体系反应慢,达最大反应强度长于12h。酸蚀后矿物结构无明显变化,可溶硅离子浓度与长石矿物、粘土矿物上述酸化体系中平均浓度相近。通过快速返排残酸,使用低浓度的HF酸进行酸化,采用过量的后置酸液以及在酸化液中加入相应的阻垢剂可预防砂岩酸化时硅质沉淀的产生。

Study on Stability of Quartz in Acidization System

The chemical reactions of quartz with the seven acid systems,such as 5%HCl,5%HCl + 0.5%HF,5%HCl + 1.0%HF,0.5%HF,1.0%HF,8%HBF4,5%HCl+7%HBF4,at 60℃,have been systematically investigated by utilizing X’Pert PRO X-ray and spectrophotometer measurement.The concentration variation feature and influencing factor of solvable Si ion in acid liquor have been especially analyzed.It is concluded that under the experiment conditions,the reactions of HF/mud acid with quartz are very fast and intensive,especially in the initial 2 hours,Si ion concentration have changed large.This is the main time of silicon precipitation.The reaction with fluoride boric acid is slow,the time of reaching maximum reaction intensity is longer than 12h;the quartz crystal structure after acid etching didn’t change obviously,however,all crystal faces of quartz are significant difference in acid.Through flowing back residual acid quickly,acidizing by low-concentration HF acid,and using excess post acid liquid as well as adding the appropriate scale inhibitors can prevent the production of silicon precipitation in sandstone acidification.