无土相油基钻井液用增黏提切剂的合成及性能

Synthesis and properties of a tackifying and shear strength-improving agent for clay-free oil-based drilling fluids

采用乳液聚合法制备出适用于无土相油基钻井液的增黏提切剂，考察了单体配比、单体加量、引发剂加量、交联剂加量、乳化剂加量、反应温度及反应时间对产物增黏提切性能的影响；采用FTIR、纳米激光粒度分析仪及金相电子显微镜对该增黏提切剂的结构和粒径进行了表征，并对其在柴油及无土相油基钻井液体系中的性能进行了评价。优化出最佳合成条件为：单体配比n（甲基丙烯酸十六酯）∶n（苯乙烯）=5∶5，单体加量（w）为30%～35%，引发剂过硫酸钾加量（w）为0.7%～0.9%，交联剂二乙烯基苯加量（w）为0.6%～0.8%，反应温度80～85℃，反应时间6～7 h，乳化剂配比m（十二烷基苯磺酸钠）∶m（OP-10）=1∶1.5，乳化剂加量（w）为5%～6%。表征结果显示，该增黏提切剂平均粒径在96 nm左右。实验结果表明，当其加量为柴油的3%（w）以上时，基浆动塑比在0.5以上，在80～160℃内变化不大，150℃下连续老化72 h性能稳定；在149℃、55.5 MPa下，该增黏提切剂在柴油中的动塑比为0.470，在无土相油基钻井液体系中的动塑比为0.200，具有更好的悬浮稳定性能。

A tackifying and shear strength-improving agent which could be used in clay-free oil-based drilling fluids was synthesized through emulsion polymerization. The effects of monomer ratio, monomer dosage,crosslinking agent dosage,initiator dosage,emulsifier dosage, reaction temperature and time on the performances of the product were investigated. Its structure and particle size were characterized by FTIR,nano particle size analyzer and metallographic electron microscope,and its performances diesel oil and clay-free oil-based drilling fluid were evaluated separately. The optimized synthesis conditions were n（hexadecyl methacrylate）∶n（styrene） of 5∶5,monomer dosage of 30%（w）-35%（w）,initiator potassium persulfate dosage of 0.7%（w）-0.9%（w）,crosslinking agent divinyl benzene dosage of 0.6%（w）-0.8%（w）,temperature of 80-85℃, time of 6-7 h,and composite emulsifier dosage of 5%（w）-6%（w） with m（sodium dodecyl benzene sulfonate）∶m（OP-10） of 1∶1.5. The characterization results showed that the average particle size of the tackifying and shear strength-improving agent was about 96 nm. The experimental results indicated that,when the addition of the tackifying and shear strength-improving agent was more than 3%of diesel oil,the ratio of the yield point to the plastic viscosity was above 0.5 and changed little in the temperature range of 80-160℃;its properties remained stable after continuous aging at 150℃for 72 h. Under the conditions of 149℃and 55.5 MPa,the ratios of the yield points to the plastic viscosities in diesel oil and clay-free oil-based drilling fluid were 0.470 and 0.200,respectively,with good suspension stability.