双亲纳米SiO_(2)颗粒的制备及提高渗吸采收率性能

Preparation and enhanced imbibition recovery factor performance of amphiphilic nano-SiO_(2) particles

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SiO_(2)颗粒表面进行改性,得到具有磺酸基和辛基的双亲纳米SiO_(2)颗粒。通过FTIR和TG对其化学结构和热稳定性进行了分析。将双亲纳米SiO_(2)颗粒分散在地层水中制备了纳米流体,对其稳定性、界面性质和渗吸效率进行了评价。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30d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SiO_(2)颗粒(含量为0.05%,以地层水质量为基准)将油水界面张力降低至1.7mN/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。

Hydrophilic nano-SiO_(2) particles were modified using n-octyl triethoxysilane and 3-mercaptopropyl triethoxysilane as modifiers and hydrogen peroxide as oxidant in a water-based environment to obtain amphiphilic nano-SiO_(2) particles containing sulfonic groups and octyl groups.The chemical structure and thermal stability were analyzed by FTIR and TG.The amphiphilic nano-SiO_(2) particles were dispersed in the formation water to prepare nanofluid,and the stability,interface properties,and imbibition efficiency of nanofluid were evaluated.The migration rule of crude oil in core pores during nanofluid imbibition was explored by nuclear magnetic resonance technology.The results indicated that the nanofluid was stored for30 d without delamination phenomenon and therefore exhibited good stability.The hydrophilicity of the core treated with the nanofluid was enhanced.Furthermore,the amphiphilic nano-SiO_(2) particles(content of 0.05%,based on the mass of formation water)could reduce the interfacial tension between oil and water to 1.7 mN/m.An imbibition recovery rate of up to 22.6% was achieved with the nanofluid.The crude oil in small pores was discharged in the initial stage of imbibition,while that in large pores was discharged in the later stage of imbibition.