随钻堵漏用疏水缔合聚合物的作用机理分析

摘要

针对常规堵漏材料难以对非均质强的渗透地层实现随钻封堵的难题,以长碳链烷基二甲基烯丙基氯化铵、丙烯酰胺、N-乙烯基吡咯烷酮和丙烯酸为单体,通过调整引发剂比例和种类及反应条件后,合成了一种随钻堵漏用疏水缔合聚合物JD.通过红外光谱表征,合成产物为4种单体的共聚物.分别对0.3％和0.6％的JD溶液及加有0.3％JD的4％膨润土浆进行透射电镜分析表明,聚合物分子之间通过疏水缔合形成了类似胶束的疏水缔合结构,其尺寸约为0.1～0.2 μm,同时疏水缔合聚合物与膨润土之间形成了动态网架结构,这正是其具有优良封堵性能的原因.通过使用FEIQuanta200F场发射环境扫描电镜测试得到,加入JD后的滤饼表面有大量聚合物形成的网架结构.静态封堵结果表明,在钻井液体系中加入0.3％JD,粒径为0.45～0.90 mm砂床的漏失量降低82％,粒径为0.22～0.45 mm与0.12～0.22 mm砂床可完全封堵,即JD可对不同漏失情况的砂床实现有效封堵,使钻井液可以随钻封堵非均质性渗透地层.配伍性评价表明,JD与SMP-Ⅱ、SPNH、聚合醇有良好的复配效果,与Redu1、NH4-HPAN、乳化沥青复配黏度和切力有所增大,因此JD更适用于黏度和切力不太高的体系.%A hydrophobically associating polymer,JD,has been synthesized with long chain alkyl dimethyl allyl ammonium chloride,acrylamide,N-vinyl pyrrolidone and acrylic acid in a certain ratio of initiators and a certain polymerization condition.JD was developed to deal with the difficulties in plugging highly heterogeneous permeable formations with conventional lost circulation materials (LCMs).IR characterization showed that JD was a copolymer of the four monomers.Analyses of a 0.3％ JD solution,a 0.6％ JD solution and a 4％ bentonite slurry containing 0.3％ JD with transmission electron microscope (TEM) demonstrated that a micelle-like hydrophobically associating structure,with sizes between 0.1-0.2 μm,was formed among the polymer molecules.Meanwhile,a dynamic network was formed between the molecules of JD and bentonite particles,a reason for JD to have superior plugging performance.Using FEI's Quanta200F (a field emission environmental scanning electron microscope) to examine the mud cake formed by a JD treated drilling fluid,it was found that a network structure was generated on the surface of the mud cake by the polymer molecules.In static plugging experiment with a drilling fluid treated with 0.3％ JD,it was found that mud losses through a 0.45 mm-0.90 mm sand bed was reduced by 82％,and sand beds of 0.22 mm-0.45 mm and 0.12 mm-0.22 mm were completely plugged,with almost no mud loss.This meant that JD can be used to plug heterogeneous permeable formations to prevent mud losses of different rates.In laboratory experiments,JD showed good compatibility with SMP-Ⅱ,SPNH and poly glycols.When mixed with Redul,NH4-HPAN and emulsified asphaltene,the viscosity and the gel strengths of the mixtures were increased to some extent,making JD more suitable for use in drilling fluids with moderate viscosity and gel strengths.