水基钻井液低温流变性调控用温敏聚合物研制及性能评价

在深水钻井过程中，水下的低温、高压环境使钻井液黏度迅速增加，造成当量循环密度（ECD）增大，由此引发井塌、井漏以及压力控制难等问题。采用乙烯基己内酰胺（NVCL）作原料，偶氮二异丁腈（AIBN）作引发剂，通过自由基聚合的方式对深水水基钻井液低温流变性具有调控作用的温敏聚合物-聚N-乙烯基己内酰胺（PVCL）进行合成。通过红外光谱、凝胶渗透色谱等方法对PVCL进行了结构表征和分子量测定，并研究了矿化度、pH值、PVCL浓度等因素对其低临界溶解温度（LCST）的影响。实验结果表明，PVCL有着较强的抗温、抗盐能力，能够使水基钻井液塑性黏度、表观黏度和动切力在4~60℃范围内变化减小50%。

Development and performance evaluation of thermo-sensitive polymer for low-temperature rheology control of water-based drilling fluid

In the process of deep water drilling, the viscosity of drilling fluid increases rapidly due to underwater low-temperature and high-pressure environment, which results in the increase of equivalent circulation density (ECD). Therefore, the problems such as well collapse, loss and pressure control have been induced. Adopting NVCL as material and AIBN as initiating agent, the thermo-sensitive polymer-poly N-vinyl caprolactam (PVCL)applicable for low-temperature rheology control of deep water-based drilling fluid is synthetized by the means of free-radical polymerization. Using methods such as the IR spectrum and gel permeation chromatography (GPC), the structure characterization and molecular weight determination of PVCL are conducted. Moreover, a research is done on how the factors such as salinity, pH value and PVCL concentration influence the lower critical solution temperature (LCST). The experiment results show that PVCL has high temperature resistance and salt tolerance, leading to the changes in plastic viscosity, apparent viscosity and yield point of water-based drilling fluid decreased by 50% within the temperature of 4-60℃