硅烷偶联剂改性纳米SiO2封堵剂的制备与作用机理

以正硅酸乙酯（TEOS）为硅源，氨水为催化剂，水为促进剂，苯乙胺丙基三甲氧基硅烷为表面改性剂，采用溶胶-凝胶法，制备了一种具有核壳结构的改性纳米SiO₂。借助傅立叶红外光谱（FT-IR）、激光粒度分析仪（PSDA）和透射电镜（TEM），表征了改性纳米SiO₂的分子结构，并对比了其与未改性纳米SiO₂在钻井液滤液中的粒度分布和微观形貌特征。通过模拟纳微米级孔隙地层封堵率测试实验，评价了不同纳米SiO₂对纳微米微裂隙的封堵能力，并探讨了其在钻井液中纳米级分散作用机理。实验结果表明，改性纳米SiO₂在钻井液中呈现纳米级分散，相比于未改性SiO₂而言，可有效对纳微米裂隙进行封堵；当质量百分浓度为3.0%时，对模拟纳微米级地层的封堵率达到99.21%。 

Preparation and Analyses of Nano SiO2 Plugging Agent Modified with Silane Coupling Agent

A modified nano SiO2 with core-shell structure was prepared through sol-gel method, using tetraethoxysilane (TEOS) as the source of Si, ammonia water as catalyst, water as accelerant, and phenylethylamine propyl trimethoxy silane as surface modifier. The molecular structure of the SiO2 was characterized through FT-IR, PSDA and TEM, and the modified SiO2 was compared with nonmodified SiO2 as to the particle size distribution and microscopic morphology in the filtrate of drilling fluid. Several nano SiO2 additives were evaluated by testing their capabilities to plug nano fractures on a simulator, and the mechanism of nano-dispersion of these SiO2 additives in drilling fluids was discussed. Compared to non-modified SiO2, the modified SiO2 shows nano-dispersion in drilling fluids, and can effectively plug the nano-sized fractures. At a concentration of 3.0%, 99.21%of the nano-sized fractures on the simulator were plugged.