CTAB诱导膨润土乳液转相机理及其在可逆乳化油基钻井液中的应用

Phase transition mechanism of CTAB inducing bentonite emulsion and its application in reversible emulsification oil-based drilling fluids

针对目前油基钻井液对油井完井损害问题,结合Pickering乳液高稳定性的特点,通过改变表面活性剂CTAB的浓度,采用原位活化工艺制备了具有不同表面润湿性的膨润土固体颗粒,研究了CTAB诱导膨润土乳液转相机理。Zeta电位及接触角的变化表征膨润土颗粒亲水、亲油性及表面润湿性的变化;膨润土乳液体系电导率及微观形貌的变化表征乳液转相行为。实验结果表明,通过改变CTAB浓度可实现对膨润土颗粒表面润湿性的改变,进而诱导膨润土乳液发生两次相转变行为。应用性能研究表明,该可逆乳化油基钻井液体系热稳定性良好,滤失量小,解决了传统油基钻井液对油井完井的损害问题。

This study focused on the current oil-well completion damage made by oil-based drilling fluids.Based on the high-stability characteristic of Pickering emulsion,and through changing the concentration of surfactant CTAB,the bentonite solid particles with different surface wettability were prepared using the in-situ activation technology,so as to study the phase transition mechanism of CTAB inducing bentonite emulsion.The hydrophilicity,hydrophobicity and surface wettability changes of bentonite particles were characterized by Zeta potential and contact angel changes,and the emulsion phase-transition behavior was featured by changes in the conductivity and micro-morphology of bentonite emulsion system.The experiment results show that the surface wettability changes of bentonite particles can be achieved by changing CTAB concentration,and then twice phase transition behaviors can be induced in bentonite emulsion.Moreover,the research on application performance indicates that this reversible emulsion oil-based drilling fluid system has favorable thermal stability with small filtration,so as to avoid the damage to the oil-well completion caused by traditional oil-based drilling fluids.