To overcome the persistent challenge of unstable water control efficacy observed in field tests for high-temperature, high-salinity gas reservoirs with excessive water production, the performance mechanism of a developed in-situ self-emulsifying nanoparticle-enhanced, oil-selective water control agent was investigated. Using a high-temperature and high-pressure micro-shear emulsification method that simulated reservoir conditions, the interfacial structure and dynamic/static structural stability of the generated Pickering emulsion were examined. The synergistic effect strength differences in forming Pickering emulsions among different water control system compositions were compared. Results indicate that the synergy between nanoparticles and emulsifier can form a highly internal W/O Pickering emulsion with formation water four times its own volume. This emulsion exhibits tolerance to high temperature and high salinity, possessing solid-like structural properties. Furthermore, the highly stable three-dimensional structure formed by nanoparticle aggregation within the continuous oil phase imparts strong dynamic structural stability to the water control system. Rheological curves show that the initial deformation of the Pickering emulsion causes the fracture of the three-dimensional structure in the continuous phase, leading to the directional arrangement of nanoparticles and the formation of a more stable multi-point connection structure. This increases the critical strain at which water control capability remains stable during water phase blockage. The findings provide deeper insights into the in-situ emulsification process and the water control mechanism of Pickering emulsions, establishing a theoretical foundation for their improvement.
SUN Xiang-yu, WANG Shi-yao, WEN Jing, XIAO Chuan-min, GE Ji-jiang, YUAN Meng.
Mechanism of High-efficiency Water Control by In-situ Emulsified Pickering Emulsions[J].
Science Technology and Engineering, 2026, 26(20): 8606-8613 DOI:10.12404/j.issn.1671-1815.2506552
通过共聚焦激光扫描显微镜(cryogenic scanning electron microscopy,Cryo-SEM)大量观测对比,发现对于产生能强协同作用的乳化体系形成的Pickering乳状液,其乳状液连续相中的致密交联结构是连续的三维网络结构,液滴被包裹在三维结构中。单纯乳化剂形成的乳状液无法形成这种三维结构,表明纳米颗粒是生成三维结构的基础,如图4(a)所示。观察具有三维结构的乳状液中的单独液滴,可以发现三维结构断裂留在液滴上的纳米颗粒连接骨架,该骨架是由吸附在液滴界面填充乳化剂间隙的纳米颗粒延伸出来的树枝状结构,如图4(b)所示。连续相中的纳米颗粒通过颗粒间疏水作用和范德华力进行聚集,形成链状或絮状的初级结构,大量初级结构相互穿插和纠缠形成了交联支架式三维结构,并与界面上吸附的纳米颗粒联结。形成的三维网络填充在油相中大幅限制了油相分子自由流动的同时也将乳状液液滴封锁在其中,阻止了液滴的聚并和沉降,因此三维骨架连接的团簇状乳状液整体不易被破坏, Pickering乳状液静态结构稳定性强。
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