研究超支化聚乙烯亚胺作为水基钻井液高性能页岩抑制剂的应用潜力,通过膨润土线性膨胀实验、造浆实验、沉降实验以及泥页岩热滚回收实验等手段对不同相对分子质量聚乙烯亚胺的抑制性能进行评价,考察不同相对分子质量聚乙烯亚胺对无土相钻井液体系性能的影响.结果表明:超支化聚乙烯亚胺能够有效抑制膨润土和泥页岩的水化分散,其中相对分子质量为600和750000的聚乙烯亚胺抑制效果相对最强;低相对分子质量聚乙烯亚胺主要通过抑制膨润土晶层膨胀以及中和膨润土颗粒外表面负电荷来抑制膨润土的水化膨胀、分散,而高相对分子质量聚乙烯亚胺主要通过超支化分子链的架桥作用抑制膨润土颗粒的分散;高相对分子质量聚乙烯亚胺尽管抑制性优异,但是与阴离子聚合物类处理剂配伍性较差,而低相对分子质量聚乙烯亚胺对体系的流变性和滤失量基本没有负面作用,甚至能够小幅提高体系切力,改善体系的携岩和悬浮加重材料的能力.%The application potential of Hyper-branched poly( ethyleneimine) ( PEI) as high-performance shale inhibitor in water-based drilling fluid was studied. The inhibitive performance of PEIs with different relative molecular weight was evalua-ted by bentonite linear swelling test, inhibition test, sediment test, and shale dispersion test, through which the influence of PEIs with different relative molecular mass on the performance of clay-free drilling fluid was investigated. The results indicate that PEI can effectively inhibit the hydration dispersion of bentonite and shale. Among all the tested samples, it is found that PEIs with molecular weight ranging from 600 to 750000 show the best inhibitive performance. For the PEI with low molecular weight the hydration swelling and dispersion of bentonite is inhibited through inhibiting crystalline swelling and neutralizing negative charges on outer surfaces of bentonite crystals. However, PEI with high molecular weight PEI inhibits the swelling and dispersion of bentonite through bridging effect of hyper-branched polymer chains. Although the inhibitive performance of PEI with high molecular weight is excellent, its compatibility with negative charged polymer-typed additives is poor. Howev-er, PEI with low molecular weight has no negative effect on the rheology and the filtrate loss of drilling fluid. Also, it can in-crease the shearing force of the system slightly and improve the capacity of carrying and suspending rock debris and weighting material.
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