黏弹性表面活性剂CTAB在钻井液中的应用

Application of Viscoelastic Surfactant CTAB in Drilling Fluid

蒋官澄 张 强 张志行

JIANG Guan-Cheng ZHANG Qiang ZHANG Zhi-Hang

实验研究了阳离子型黏弹性表面活性剂十六烷基三甲基溴化铵（CTAB）溶液的流变性、抗温性、降滤失性及配套破胶剂的破胶性能。室内实验结果表明：将2%CTAB与3%助剂水杨酸钠NaSal混合的基液在剪切速率170 s-1、温度25℃、pH=7的情况下混合均匀后能迅速增黏至160 mPa·s；加入少量复合降滤失剂LA（水解聚丙烯腈铵（NH4-HPAN）和磺化酚醛树脂（SMP-Ⅱ）混合而成的复合体系）可显著降低其常温常压滤失量；高效破胶剂Br的破胶性能良好，破胶剂的黏度降至1-3 mPa·s。同时室内研究了以阳离子型黏弹性表活性剂CTAB为主剂的钻井液体系——表面活性剂胶束钻井液DIF-a：1.5%CTAB + 2.0%NaSal+1.2%复合降黏剂LA + 0.5%黄胞胶XC，结果表明：在钻探碳酸盐岩地层时钻井液体系DIF-a产生的流动摩阻小、降滤失性能较好，且钻完井后利于返排，储层渗透率保留率可以达到91.41%，大大降低外部流体对储层造成的损害。

The properties of cationic viscoelastic surfactant CTAB solution, including rheology, temperature resistance, fluid loss and gel breaking performance of matched breaker through experiments, were studied. Experimental results showed that viscosity of the system, prepared by mixing 2% CTAB with 3% additives sodium salicylate(NaSal), increased to 160 mPa·s at the shear rate of 170 s-1, at the temperature of 25℃ and at pH value of 7. The filter loss droped greatly at the existence of a few fluid loss agent LA, composed of hydrolyzed polyacrylonitrile ammonium (NH4-HPAN) and sulfonated phenolic resin (SMP-Ⅱ). The viscosity of the gel breaking fluid was significantly reduced to 1—3 mPa·s when a gel breaker Br was added, which showed a good performance on the gel breaking. A new drilling fluid system with cationic viscoelastic surfactant CTAB as the main agent——surfactant micellar drilling fluid DIF-a (1.5%CTAB+2.0%NaSal+1.2% compound additive agent LA+0.5% xanthan gum XC) was studied. The results showed that small flow friction, good fluid loss performance as well as easier flowback after completion was generated using drilling system DIF-a when drilling in carbonate formation. Ultimately, the retention rate of the reservoir permeability could reach up to 91.41% and reservoir damage of the external fluid was greatly reduced.