The hydration and swelling of shale formations are serious problems for well drilling. The use of an efficient shale inhibitor is one of the most important methods for overcoming the wellbore instability issue. In this work, poly-l-arginine (PArg) was synthesized and used as an efficient and biodegradable shale inhibitor. This inhibitor was systematically evaluated through measuring the swelling degree of the bentonite (Bent) pellet, the rheological behavior of the Bent suspensions, and the recovery percentage of shale cuttings. The results demonstrated that 2.0 wt % PArg could reduce the swelling degree of Bent to 70.53%, improve the shale recovery percentage to 71.40% at 180 °C, and inhibit 12.0 wt % Bent mud-making. The PArg displayed a highly inhibitive performance and excellent high-temperature resistance property, better than common inorganic KCl and organic polyether diamine. The underlying inhibition mechanism was also proposed based on measuring the variation of the interlayer spacing of the Bent, observing the exterior morphologies of Bent particles, and assessing the particle size distribution and electrokinetic potential. The results indicated that the PArg displayed its inhibitive effect mainly by adsorbing onto the Bent, encapsulating the Bent particles efficiently, and decreasing the interlayer spacing in a certain degree with 0.9 Å. This study can contribute to designing highly inhibitive water-based drilling fluids containing PArg.

中文翻译：

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聚-1-精氨酸作为稳定钻井孔的水基钻井液中的高性能和可生物降解的页岩抑制剂

页岩地层的水合作用和溶胀是钻井的严重问题。有效的页岩抑制剂的使用是克服井眼失稳问题的最重要方法之一。在这项工作中，聚升合成了精氨酸（PArg），并用作有效且可生物降解的页岩抑制剂。通过测量膨润土（Bent）颗粒的溶胀度，Bent悬浮液的流变行为以及页岩屑的采收率来系统地评估该抑制剂。结果表明，2.0 wt％PArg可以将Bent的溶胀度降低至70.53％，在180°C下可提高页岩采收率至71.40％，并抑制12.0 wt％的Bent泥浆形成。PArg具有较高的抑制性能和优异的耐高温性能，优于普通的无机KCl和有机聚醚二胺。还通过测量Bent的层间间距的变化，观察Bent颗粒的外部形态，提出了潜在的抑制机制。并评估粒度分布和电动势。结果表明，PArg主要通过吸附在Bent上，有效地包裹Bent颗粒，并在一定程度上将层间间距减小0.9来发挥抑制作用。这项研究可有助于设计含有PArg的高度抑制性的水基钻井液。