异电荷聚电解质自组装水凝胶在无固相煤层气钻井液中的特性

基于异电荷聚电解质之间的分子自组装,以线型阴离子聚电解质APE和超支化阳离子聚电解质CPE制备了一种高性能水凝胶。相行为研究结果表明,APE与CPE在清水中共存时将以络合物的形态析出,大量的NaCl则可通过"聚电解质效应"将络合物解离。流变性测试结果表明,通过与APE之间的强静电作用,CPE增强了APE溶液中被盐破坏的凝胶网络结构,有效改善了悬浮性与剪切稀释性。APE-CPE水凝胶具有优良的高温稳定性,在饱和盐侵下的抗温能力优于一般的阴离子及两性离子聚电解质水凝胶。APE-CPE水凝胶同时具备良好的抑制、包被性能,易被破胶剂破胶且残渣率低。以APE-CPE水凝胶为基础,研制了配方简单、使用NaCl加重的低密度无固相煤层气钻井液。

Properties of self-assembled hydrogel of oppositely-charged polyelectrolytes in solid-free coalbed methane drilling fluid

Based on self-assembly between oppositely-charged polyelectrolytes, a high-performance hydrogel is prepared utilizing linear anionic polyelectrolyte (APE)and hyperbranched cationic polyelectrolyte (CPE). The phase behavior research indicates that APE and CPE precipitate as complex coacervate in aqueous solution. The APE-CPE coacervate can be dissociated by large quantities of NaCl under "polyelectrolyte effect". Rheology tests indicate that CPE strengthens gel network of APE in brine by strong intermolecular electrostatic forces, and therefore effectively improves suspending and shear-thinning performance. Compared with common anionic and amphoteric polyelectrolyte hydrogel, APE-CPE hydrogel owns much better high-temperature stability. In addition, APE-CPE hydrogel possesses well inhibition and encapsulation performance. The gel structure can be easily broken by gel breakers, leaving low residue content. On the basis of APE-CPE hydrogel, a low-density, solid-free coalbed methane drilling fluid weighted by NaCl is prepared with simple formula.