分子模拟有机胺页岩抑制剂碳链长度对抑制性能的影响

Molecular Simulation for the Effect of Organic Amine Shale Inhibitor’s Carbon Chain Length on Its Inhibition Performance

有机胺钻井液体系近年来在国内外备受关注,其实质是应用了新的有机胺页岩抑制剂,因此更高效地研发胺类抑制剂是有机胺钻井液技术发展的关键。为研究有机胺类页岩抑制剂碳链长度对其抑制性能的影响规律和其抑制作用产生的作用机理,通过分子模拟方法研究了不同直链状有机胺分子——乙二胺、1,4-丁二胺、1,6-己二胺、1,8-辛二胺、1,10-癸二胺的抑制性能变化规律,并通过分子动力学方法研究了有机胺页岩抑制剂对Na-蒙脱石水化抑制的作用机理以及有机胺页岩抑制剂对蒙脱石晶体力学性质的影响。结果表明,这些有机胺分子的抑制性能有明显的差异,1,6-己二胺的水化抑制效果最佳,乙二胺和1,10-癸二胺的抑制效果较差。可见,分子结构为直链状且两端为胺基的有机胺分子的水化抑制性随碳链长度的增加呈先增后减的趋势,且在含有6个碳原子(1,6-己二胺)时水化抑制效果和蒙脱石力学性能均达到最佳。

The organic amine base drilling fluid system has attracted much attention at home and aboard in recent years.Its essence is the application of new organic amine shale inhibitor.Therefore,the development of efficient amine shale inhibitor is the key to the development of organic amine base drilling fluid technology.Organic amine molecules of linear chain with smaller molecular weight,such as ethylenediamine,1,4-butanediamine,1,6-hexanediamine,1,8-octanediamine and 1,10-decanediamine,are selected as research objects.And organic amine shale inhibitor molecular models with different carbon chain length and sodium montmorillonite crystal model are constructed by molecular simulation.The inhibition mechanism of organic amine shale inhibitor on hydration of sodium montmorillonite and the effect of organic amine shale inhibitor on the mechanical properties of montmorillonite crystals are studied by molecular dynamics method.The results showed that there were obvious differences in the inhibition properties of these organic amines.The hydration inhibition effect of 1,6-hexanediamine was the best,while that of ethylenediamine and 1,10-decanediamine was the worst.In details,the hydration inhibition of organic amine molecules increases with the increase of the carbon chain length,and the hydration inhibition effect of organic amine molecules and mechanical properties of montmorillonite crystal are the best when the carbon chain contains 6 carbon atoms (1,6-Hexanediamine),then the hydration inhibition of carbon amine molecules decreases with the increase of carbon chain length.