双亲纳米SiO2颗粒的制备及提高渗吸采收率性能

以正辛基三乙氧基硅烷和3-巯基丙基三乙氧基硅烷为改性剂，以双氧水为氧化剂，在水基环境下对亲水纳米SiO2颗粒表面进行改性，得到具有磺酸基和辛基的双亲纳米SiO2颗粒，并通过红外和热重对其化学结构和热稳定性进行分析。将双亲纳米SiO2颗粒分散在地层水中制备纳米流体，并评价纳米流体的稳定性、界面性质和渗吸效率。利用核磁共振技术探究纳米流体渗吸过程中岩心孔隙内原油运移规律。结果表明，纳米流体储存30 d未出现分层现象，表现出良好的稳定性；经纳米流体处理的岩心亲水性增强。此外，双亲纳米SiO2颗粒将油水界面张力降低至1.7 mN/m；纳米流体渗吸采收率高达22.6%，渗吸初始阶段小孔隙中的原油被动用，而在渗吸后期阶段大孔隙中的原油才被动用。

Preparation and enhanced imbibition recovery factor performance of amphiphilic nano-SiO2 particles

With n-octyl triethoxysilane and 3-mercaptopropyl triethoxysilane as modifiers and hydrogen peroxide as oxidant, the surface of hydrophilic nano-SiO2 particles was modified in a water-based environment to obtain amphiphilic nano-SiO2 particles with sulfonic groups and octyl groups, and their chemical structure and thermal stability were analyzed by FT-IR and TG. The amphiphilic nano-SiO2 particles were dispersed in the formation water to prepare the nanofluid, and the stability, interface properties, and imbibition efficiency of the nanofluid were evaluated. Nuclear magnetic resonance technology was used to explore the migration rule of crude oil in core pores during the nanofluid imbibition. The results indicated that the nanofluid was stored for 30 d without delamination phenomenon and therefore exhibited good stability. The hydrophilicity of the core treated with the nanofluid was enhanced. Furthermore, the amphiphilic nano-SiO2 particles could reduce the interfacial tension to 1.7 mN/m. An imbibition recovery factor of up to 22.6% was achieved with the nanofluid. In the initial stage of the imbibition, crude oil in small pores was discharged, while in the later stage of the imbibition, crude oil in large pores was discharged.