Nanoparticles with high surface energy and chemical activity have drawn substantial attention in petroleum industry. Recently, Janus nanoparticles exhibited tremendous potential in enhanced oil recovery (EOR) due to their asymmetric structures and properties. In this study, a series of amphiphilic pseudo-Janus@OTAB (PJ@C18) nanoparticles with different concentrations of stearyltrimethylammoium bromide (OTAB) were successfully fabricated. The structures and properties of PJ@C18 were characterized by Fourier transform infrared spectroscopy and ζ-potential measurements. Based on the emulsification experimental results, the interaction models and the self-assembly behavior between hydrophilic nanoparticles (SiO₂@NH₂) and OTAB molecules at the oil/water interface were proposed, which was further confirmed via the measurements of the contact angle and dynamic interfacial tension. Interestingly, it was found that the change of pH value from 7.5 to 4.0 caused the type reversal of the PJ@C18-1000 stabilized Pickering emulsions. Furthermore, the PJ@C18-1000 stabilized Pickering emulsion system with excellent salt and temperature tolerances (10000 mg·L⁻¹, 90 °C) significantly improved the oil recovery in the single-tube (more than 17%) and double-tube (more than 25%) sand pack model flooding tests. The findings of this study could help to better understand the construction mechanism of pseudo-Janus silica/surfactant assembly and the potential application of PJ@C18-1000 stabilized Pickering emulsions for EOR.

具有高表面能和化学活性的纳米颗粒在石油工业中引起了广泛关注。最近，Janus 纳米粒子由于其不对称的结构和性质，在提高石油采收率（EOR）方面表现出巨大的潜力。在这项研究中，成功​​地制备了一系列具有不同浓度十八烷基三甲基溴化铵（OTAB）的两亲性伪Janus@OTAB（PJ@C18）纳米颗粒。PJ@C18 的结构和性质通过傅里叶变换红外光谱和 ζ 电位测量表征。基于乳化实验结果，亲水性纳米粒子（SiO ₂ @NH ₂)和油/水界面上的OTAB分子被提出，这通过接触角和动态界面张力的测量得到了进一步证实。有趣的是，发现 pH 值从 7.5 到 4.0 的变化导致 PJ@C18-1000 稳定的 Pickering 乳液的类型反转。此外，PJ@C18-1000稳定的Pickering乳液体系具有优异的耐盐性和耐温性（10000 mg·L ^-1 , 90 °C），显着提高了单管（超过17%）和双管的采油率（超过 25%）沙包模型注水试验。本研究的结果有助于更好地理解伪Janus二氧化硅/表面活性剂组装的构建机制以及PJ@C18-1000稳定的Pickering乳液在EOR中的潜在应用。