Abstract: To address the challenges associated with the rapid gelation of silicate gels, which can readily cause wellbore blockage and formation damage and thus hinder efficient fluid diversion, this study proposes a temperature-salt dual-responsive microgel system. The approach involves loading sodium silicate onto NIPAM-based thermoresponsive copolymer microgels and subsequently encapsulating them with chitosan to construct the dual-responsive microgels. Through orthogonal experimental design, the optimal synthesis conditions for the thermoresponsive microgel carrier were determined as follows:a Span-80/Tween-80 composite emulsifier system, emulsifier dosage of 7.5 wt %, oil-to-water ratio of 4∶1, crosslinker dosage of 0.5 %, stirring speed of 400 r/min, and SA monomer content of 10 % . Using the characterization techniques such as FTIR, ¹H NMR, and SEM, it has been confirmed that the microgels possess a unique porous cavity architecture, which provides a structural foundation for efficient sodium silicate loading. Phase transition behavior analysis shows that the thermoresponsive microgels exhibit excellent hydration and swelling performance at low temperatures, while undergoing volume shrinkage above the lower critical solution temperature (LCST). The chitosan-coated dual-responsive microgels extend the sodium silicate release duration to 10 days. Under reservoir temperature conditions, the temperature-salt responsive microgel system forms a microgel/silicate composite gel, achieving a core plugging efficiency of over 60 %, demonstrating strong potential for deep fluid diversion applications.

Key words: NIPAM-based thermoresponsive microgel, sodium silicate, loading-release behavior, temperature-salt dual-responsive microgel, flow characteristics

摘要： 针对硅酸盐凝胶成胶反应速率快、容 易造成井筒堵塞和储层伤害、难以实现高效液流转向的问题,提出利用NIPAM系共聚温敏微凝胶负载硅酸钠,结合壳聚糖包裹温敏微凝胶构建温盐双响应微凝胶。通过正交试验确定了温敏微凝胶载体的最佳合成条件:乳化剂选择Span-80/Tween-80复合体系;乳化剂用量为7.5%;油水比为4∶1;交联剂用量为0.5%;搅拌速度为400 r/min;SA单体含量为10% 。利用红外光谱(FITR)、核磁共振氢谱(¹H NMR)、扫描电镜(SEM)等技术表征方法,证实了微凝胶特殊的多孔空腔结构可为硅酸钠的高效负载提供结构基础。相变行为研究结果表明,温敏微凝胶低温下具有良好水化溶胀性能,当温度高于相变温度(LCST)时温敏微凝胶可通过相变实现体积收缩,利用壳聚糖为包覆材料构建的温盐双响应微凝胶释放硅酸钠时间可延长至10 d,温盐双响应微凝胶体系在油藏温度下温盐响应形成的微凝胶/硅酸盐凝胶复合体系对岩心封堵率超过60%,具备深部液流转向应用前景 。

关键词: NIPAM系温敏微凝胶, 硅酸钠, 负载-释放规律, 温盐双响应微凝胶, 渗流特性