The increasing demands for oil and gas and associated difficult drilling operations require oil-based drilling fluids that possess excellent rheological properties and thermal stability. The objective of the present work was to investigate the rheological properties and thermal stability of organo-montmorillonite (OMnt) modified with various surfactants and under various loading levels in oil-based drilling fluids, as revealed by the interaction between organic surfactants and montmorillonite. The influence of the structural arrangement of surfactants on the thermal stability of organo-montmorillonite (OMnt) in oil-based drilling fluids was also addressed. OMnt samples were prepared in aqueous solution using surfactants possessing either a single long alkyl chain two long alkyl chains. OMnt samples were characterized by X-ray diffraction, high-resolution transmission electron microscopy, thermal analysis, and X-ray photoelectron spectroscopy. Organic surfactants interacted with montmorillonite by electrostatic attraction. The arrangements of organic surfactants depended on the number of long alkyl chains and the geometrical shape of organic cations. In addition to the thermal stability of surfactants, intermolecular interaction also improved the thermal stability of OMnt/oil fluids. A tight paraffin-type bilayer arrangement contributed to the excellent rheological properties and thermal stability of OMnt/oil fluids. The deterioration of rheological properties of OMnt/oil fluids at temperatures up to 200°C was due mainly to the release of interlayer surfactants into the oil.

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表面活性剂与蒙脱石的相互作用及其对油基钻井液中有机蒙脱石性质的影响

对石油和天然气日益增长的需求以及相关困难的钻井作业需要具有优异流变特性和热稳定性的油基钻井液。本工作的目的是研究用各种表面活性剂改性的有机蒙脱石 (OMnt) 在油基钻井液中不同负载水平下的流变特性和热稳定性，正如有机表面活性剂和蒙脱石之间的相互作用所揭示的那样。还讨论了表面活性剂的结构排列对油基钻井液中有机蒙脱石 (OMnt) 热稳定性的影响。OMnt 样品是在水溶液中使用具有单个长烷基链或两个长烷基链的表面活性剂制备的。OMnt 样品通过 X 射线衍射表征，高分辨率透射电子显微镜、热分析和 X 射线光电子能谱。有机表面活性剂通过静电引力与蒙脱石相互作用。有机表面活性剂的排列取决于长烷基链的数量和有机阳离子的几何形状。除了表面活性剂的热稳定性外，分子间相互作用还提高了 OMnt/油流体的热稳定性。紧密的石蜡型双层排列有助于 OMnt/油流体的优异流变特性和热稳定性。OMnt/油流体在高达 200°C 的温度下流变特性的恶化主要是由于层间表面活性剂释放到油中。有机表面活性剂通过静电引力与蒙脱石相互作用。有机表面活性剂的排列取决于长烷基链的数量和有机阳离子的几何形状。除了表面活性剂的热稳定性外，分子间相互作用还提高了 OMnt/油流体的热稳定性。紧密的石蜡型双层排列有助于 OMnt/油流体的优异流变特性和热稳定性。OMnt/油流体在高达 200°C 的温度下流变特性的恶化主要是由于层间表面活性剂释放到油中。有机表面活性剂通过静电引力与蒙脱石相互作用。有机表面活性剂的排列取决于长烷基链的数量和有机阳离子的几何形状。除了表面活性剂的热稳定性外，分子间相互作用还提高了 OMnt/油流体的热稳定性。紧密的石蜡型双层排列有助于 OMnt/油流体的优异流变特性和热稳定性。OMnt/油流体在高达 200°C 的温度下流变特性的恶化主要是由于层间表面活性剂释放到油中。除了表面活性剂的热稳定性外，分子间相互作用还提高了 OMnt/油流体的热稳定性。紧密的石蜡型双层排列有助于 OMnt/油流体的优异流变特性和热稳定性。OMnt/油流体在高达 200°C 的温度下流变特性的恶化主要是由于层间表面活性剂释放到油中。除了表面活性剂的热稳定性外，分子间相互作用还提高了 OMnt/油流体的热稳定性。紧密的石蜡型双层排列有助于 OMnt/油流体的优异流变特性和热稳定性。OMnt/油流体在高达 200°C 的温度下流变特性的恶化主要是由于层间表面活性剂释放到油中。