Abstract Shale hydration and dispersion leading to wellbore instability is always a challenge in oil and gas drilling engineering. In this study, specifically designed nano-particles by grafting hyperbranched polyethyleneimine (Mw = 600) onto the surface of nano-silica particles were synthesized. The modified nano-particles were characterized with Fourier transform infrared spectrum (FT-IR), particles size distribution measurement, thermal gravimetric analysis (TGA), transmission electron microscope (TEM) and zeta potential measurement. The results indicated that after modification, the nano-particles became positively charged and showed better dispersion in water compared to pristine nano-silica particles. Shale cuttings hot-rolling dispersion test and linear swelling test as chemical inhibitive tests in combination with pressure transmission test and shale sample spontaneous imbibition test as physical plugging tests were used to evaluate the shale stabilizing performance of the modified nano-particles. The results showed that the modified nano-particles exhibited both effective chemical inhibition and physical plugging, whereas nano-silica only showed limited physical plugging. The interaction between modified nano-silica particles and shale demonstrated that the grafted hyperbranched polymer strongly adsorbed onto the clay surface via electrostatic interaction and hydrogen bonding, which resulted in effective inhibition of shale hydration and swelling. After adsorption, the modified nano-silica particles were trapped on the micropores of shale formation and prevented the fluid invasion. The dual functions of the modified nano-silica particles demonstrated a remarkable improvement of shale stability.

中文翻译：

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纳米二氧化硅接枝超支化聚乙烯亚胺提高水基钻井液中页岩稳定性

摘要 页岩水化分散导致井筒失稳一直是油气钻井工程中的难题。在这项研究中，通过将超支化聚乙烯亚胺（Mw = 600）接枝到纳米二氧化硅颗粒的表面上合成了专门设计的纳米颗粒。通过傅里叶变换红外光谱（FT-IR）、粒度分布测量、热重分析（TGA）、透射电子显微镜（TEM）和zeta电位测量对改性纳米颗粒进行了表征。结果表明，改性后的纳米颗粒带正电，与原始纳米二氧化硅颗粒相比，在水中表现出更好的分散性。采用页岩岩屑热轧分散试验和线性溶胀试验作为化学抑制试验，结合压力传递试验和页岩样品自吸试验作为物理封堵试验，评价改性纳米颗粒的页岩稳定性能。结果表明，改性纳米颗粒表现出有效的化学抑制和物理堵塞，而纳米二氧化硅仅表现出有限的物理堵塞。改性纳米二氧化硅颗粒与页岩之间的相互作用表明，接枝的超支化聚合物通过静电相互作用和氢键强烈吸附在粘土表面，从而有效抑制了页岩水化和膨胀。吸附后，改性纳米二氧化硅颗粒被困在页岩地层的微孔上，防止流体侵入。改性纳米二氧化硅颗粒的双重功能证明了页岩稳定性的显着改善。