重晶石螯合解堵剂作用机理及其评价方法研究

Mechanism of action and evaluation of chelating agents on barite removal

以重晶石加重剂为主要成分的钻井液滤饼形成的重晶石堵塞是造成油气储层伤害、影响油气产量的主要因素之一。常规的酸化解堵措施难以溶解重晶石堵塞物,而研制高性价比的非酸螯合解堵剂并制定科学的解堵施工工艺是解决重晶石堵塞的有效工程手段。氨基多羧酸螯合剂通过与重晶石表面的钡离子形成强螯合物,促进重晶石的快速溶解,有助于解除重晶石滤饼堵塞。文章归纳了常见的氨基多羧酸螯合剂的结构特征,从螯合解堵机理角度认为DTPA对重晶石堵塞的油气井解堵效果最佳;同时分析了常用的螯合解堵剂评价方法的优缺点,建立了一套准确、简单、快捷的重晶石螯合解堵剂性能的评价方法。相比于其他评价方法,高温动态溶解率评价方法具有实验耗时短、对实验器材要求低、实验结果直观等优点,推荐使用高温动态溶解率评价方法去评价螯合解堵剂的性能。

Barite blockage-a result of the formation of a drilling fluid filter cake with barite weighting agent as the main component-is one of the main contributing factors to reservoir damage and causes major problems in oil and gas production.As conventional acidification measures fail to remove the barite blockage,finding cost-effective,non-acid chelating agents and formulating a barite removal scheme are an effective engineering means to solve the barite blockage problem.Aminopolycarboxylic acids as chelating agents bind strongly with barium ions on the surface of barite promoting the rapid dissolution of the barite filter cake.The structural characteristics of common aminopolycarboxylic acids are summarized.From the mechanistic perspective of chelating,we consider DTPA to be most effective for the barite removal in oil and gas wells.In addition,the pros and cons of commonly used evaluation methods for chelating agents are considered,and an evaluation scheme for accurate,simple,fast performance evaluation of chelating agents is established.We recommend using the high-temperature dynamic dissolution-rate measurements to evaluate chelating reagents,as it has the advantages of short experiment time,low requirements on test equipment and intuitive test results.