络合法去除油田硫酸钡的研究与应用

以二乙烯三胺五乙酸（DTPA）为螯合剂主剂，配以氢氧化钾中和至pH值为13，并添加一定量的无机盐，对重晶石粉末进行溶出研究。结果表明，在DTPA质量分数一定的情况下，由于溶液黏度影响，钾盐的助溶效果为钠盐的2倍；随着无机盐质量分数的增加，碳酸钾、氟化钾和氯化钾对重晶石的助溶效果相应增加，碳酸钾添加量为10%时，溶出率达到最高的47.79%；反应4 h时，由于重晶石结块导致反应面积增大，碳酸钾的助溶效果比氟化钾高10.56%；反应12 h时，反应趋于完全，由于盐效应影响反应终点，氟化钾的助溶效果比碳酸钾高12.39%；对DTPABa3-离子进行了计算机模拟，得到了其稳定构象，并分析了钡离子络合常数低的原因；最终将该螯合剂应用于某堵塞油井，并对返排液中的无机盐组分、硫酸盐沉淀组分进行了XRD分析，并在沉淀中检测出钡元素，证明油井解堵成功，应用良好。 

Study and Application of Removing Oilwell Barium Sulphate through Complexing Method

The chelating agent used was mainly composed of diethylene triamine pentacetic acid (DTPA). It was neutralized with KOH until the pH was 13, and then treated with a certain amount of inorganic salts. This solution was used to dissolve out barite powders. The experimental results showed that, at a certain mass ratio of DTPA, the efficiency of potassium salts as solubilizing agent was 2 times of that of sodium salts due to the effect of the solution viscosity. Increasing the mass ratio of the inorganic salt, the efficiencies of potassium carbonate, potassium fluoride and potassium chloride as solubilizing agents in dissolving barite were correspondingly enhanced. At 10% of potassium carbonate, 47.79% of barite was dissolved. After 4 h of reaction, the conglomeration of barite led to an increase in reaction area, increasing the solubilizing efficiency of potassium carbonate to a value that was 10.56% higher than that of potassium fluoride. After reacting for 12 h, the reaction tended to complete, the solubilizing efficiency of potassium fluoride was instead higher than that of the potassium carbonateby 12.39% because of the salt effect on the reaction endpoint. The steady configuration of the DTPABa3-ions was obtained through computerized simulation, and the cause of low complexation constant of barium ions was analyzed. A chelating agent was chosen based on the study and was used on a well blocked with barite. The flowback fluid was analyzed for inorganic salts and precipitated sulphate using XRD. Barium was found in the precipitates, indicating that the well was successfully unblocked.