网状交联聚阳离子型黏土膨胀抑制剂及其作用机理

以二甲胺、环氧氯丙烷为原料，加入交联剂，合成网状交联型聚阳离子化合物黏土膨胀抑制剂，以膨润土的线性膨胀率为评价指标，优化抑制剂的合成条件，筛选出对膨润土具有较好抑制性能的抑制剂。采用防膨实验、泥球实验、钻井液性能评价实验等，综合评价所筛选出的抑制剂DEM-8对黏土稳定性能的影响。防膨实验显示0．8％DEM-8防膨率高达92．3％，泥球实验与钻井液性能评价实验表明该聚阳离子化合物有较强的抗黏土水化膨胀功能，并且能提高改性淀粉的抗温性。采用离子交换实验、扫描电镜（ SEM）、热重分析（ TGA）及X-射线衍射（ XRD）等手段深入探讨了所合成黏土膨胀抑制剂的作用机理。研究表明，该聚阳离子型化合物与黏土中的可交换阳离子迅速发生交换，通过静电引力吸附于黏土表面和层间，进一步通过氢键作用、锚固作用以及疏水作用等实现对黏土的束缚，从而有效抑制黏土的水化分散膨胀。

Network polycationic clay swelling inhibitor and its inhibition mechanism

Dimethylamine and epichlorohydrin used as raw materials ,adding a cross -linked agent ,a kind of cross -linked polycation compounds were synthesized as clay swelling inhibitor .Taking the linear expansion rate of bentonite as e-valuation index ,the synthetic conditions were optimized ,and a suitable inhibitor for bentonite was screened .Properties of the inhibitor (DEM-8) were evaluated by anti -swelling experiment,mud ball experiment,evaluation experiment of drill-ing fluid properties,etc.Experimental results showed that an anti -swelling rate of 0.8%DEM-8 reaches up to 92.3%. The mud ball experiment and the evaluation experiment of drilling fluid properties further proved that DEM -8 has stronger inhibitive capability to bentonite hydration swelling and dispersion and can improve temperature tolerance of modified starch .The inhibition mechanism of the polyamine was studied thoroughly by the means of ion exchange method ,scanning electron microscope (SEM),thermogravimetric analysis (TGA) and X-ray diffraction (XRD),etc.The results demon-strated that exchangeable cations inside clay were rapidly exchanged with the polycation compounds ,and the cations were adsorbed on clay surface through electrostatic interaction .In addition ,the polycation compounds inhibit effectively the hy-dration or swelling of clays mainly owing to hydrogen bonding ,anchoring effect and hydrophobic effect ,etc.