Abstract Non-ionic surfactants have been used as a rheology control additive in drilling fluids to prevent flocculation of solids, such as organoclays, and maintain mud dispersion. Here, the fundamental phenomena involved in non-ionic surfactant adsorption on organoclays and how it affects the rheology of synthetic-based drilling fluids were elucidated by the analysis of molecular descriptors and Monte Carlo simulations. Using the Random Forests machine learning algorithm software, the non-ionic surfactant adsorption on organoclays was found to be affected mainly by the hydrophobicity and molecular shape of hydrophobic chains of non-ionic surfactants. Molecular descriptor calculations indicated that the hydrophobic interaction and van der Waals forces are dominant factors. Then, the Monte Carlo simulations provided the empirical effect of the non-ionic surfactant hydrophobic chains on their self-assembly to organoclays. Molecules with two chains were found to be easily adsorbed to the surface due to molecular size, while molecules with three and four chains occupy more sites and interact with each other more frequently, forming larger clusters. Consequently, non-ionic surfactants with more hydrophobic chains were predicted to improve rheology of drilling fluids and form stable mud emulsions. This approach is useful in predicting the effects of new additive in drilling fluid formulation.

中文翻译：

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通过分子描述符和蒙特卡罗随机游走模拟研究钻井液中有机粘土对非离子表面活性剂的吸附

摘要 非离子表面活性剂已被用作钻井液中的流变控制添加剂，以防止有机粘土等固体絮凝，并保持泥浆分散。在这里，通过分子描述符分析和蒙特卡罗模拟阐明了非离子表面活性剂吸附在有机粘土上的基本现象及其如何影响合成钻井液的流变学。使用随机森林机器学习算法软件，发现非离子表面活性剂在有机粘土上的吸附主要受非离子表面活性剂疏水链的疏水性和分子形状的影响。分子描述符计算表明疏水相互作用和范德华力是主要因素。然后，Monte Carlo 模拟提供了非离子表面活性剂疏水链对其自组装成有机粘土的经验影响。发现具有两条链的分子由于分子大小而容易吸附到表面，而具有三条和四条链的分子占据更多位点并且彼此更频繁地相互作用，形成更大的簇。因此，预测具有更多疏水链的非离子表面活性剂可改善钻井液的流变性并形成稳定的泥浆乳液。这种方法可用于预测新添加剂在钻井液配方中的作用。而具有三链和四链的分子占据更多的位点并更频繁地相互作用，形成更大的簇。因此，预测具有更多疏水链的非离子表面活性剂可改善钻井液的流变性并形成稳定的泥浆乳液。这种方法可用于预测新添加剂在钻井液配方中的作用。而具有三链和四链的分子占据更多的位点并更频繁地相互作用，形成更大的簇。因此，预测具有更多疏水链的非离子表面活性剂可改善钻井液的流变性并形成稳定的泥浆乳液。这种方法可用于预测新添加剂在钻井液配方中的作用。