磷钨酸法测定钻井液材料中有机阳离子的探讨

Studies on the Phosphotungstic Acid Method to Determine the Organic Cations of Drilling Fluid Materials

周姝娜 湛玉玲 黄伟琴 张月华

ZHOU Shu-Na ZHAN Yu-Ling HUANG Wei-Qin ZHANG Yue-Hua

磷钨酸法是测定两性离子表面活性剂阳离子度的经典方法，经实验验证该方法可用于测定钻井液材料中的阳离子或两性离子的含量。含有有机阳离子基团的钻井液材料由于其成分复杂，试样溶液颜色较深，不易准确测定其中的有机阳离子度。本文采用钠型阳离子交换树脂对产品进行提纯，在弱酸性条件下，以刚果红为指示剂，用磷钨酸标准溶液定量测定有机阳离子度，实验相对误差是0.59%。本文介绍了方法原理、操作程序及方法验证。结果表明，采用磷钨酸法测定钻井液中的有机阳离子含量不受阴离子的干扰，而且无机阳离子对测定结果也无影响。经岩心相对回收率实验，测定结果和使用性能相吻合，结果准确可靠。

Phosphotungstic acid method is a classical method to measure the Cationic degree of zwitterionic surfactant, and the method can be also used to determine the content of cations or zwitterions of the drilling fluid materials. It is not easy to determine the organic cationic degree of drilling fluid materials containing organic cationic groups accurately due to the complex composition and the deeper colour of sample solution. In this paper, products was purified first by cation exchange resin of sodium type, then the phosphotungstic acid standard solution was used to determine the organic cation degrees quantitatively with congo red as indicator in weak acidic conditions. The experimental relative error was 0.59%. In the paper, the method, principle, operating procedure and method validation was introduced. The results showed that the organic cation content of the drilling fluid could be determined with phosphotungstic acid method, which is free of anion and inorganic cations. The core relative recovery experiment also showed that the measurement results fitted in well with the usability, and the results were reliable.