一种两性离子聚合物凝胶微球的制备与封堵性能

针对油基钻井液封堵性不足的难题，以N,N-二甲基丙烯酰胺（DAM）、2-丙烯酰胺基-2-甲基丙磺酸（AMPS）和二烯丙基二甲基氯化铵（DMDAAC）为单体，以N,N-亚甲基双丙烯酰胺（MBA）为交联剂，采用悬浮聚合法合成了一种两性离子聚合物凝胶微球。采用核磁共振氢谱对凝胶微球进行了分子结构表征，并考察了单体投料比、交联剂加量、乳化剂加量等对凝胶微球粒径与封堵性能的影响规律，最终将单体投料比优选为DAM∶AMPS∶DMDAAC=7∶1∶2，MBA加量优选为单体总质量的0.2%，乳化剂加量优选为单体总质量的3%，得到的凝胶微球平均粒径在22 μm左右。在油基钻井液中评价了微球的封堵性能，结果表明，凝胶微球在油基钻井液中的适应性良好，能够在高温下封堵尺寸为5～150 μm范围内的漏缝，效果优于氧化沥青与细目碳酸钙，是一种高性能的微米级封堵剂，具有较好的现场应用潜力。 

Preparation and Plugging Performance of Zwitterionic Polymer Gel Micro Spheres

A kind of zwitterionic polymer gel micro spheres have been prepared through suspension polymerization to address the deficiency of plugging capacity of oil based drilling fluids. The raw materials used in the polymerization include N , N -dimethyl acrylamide (DAM), 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and dimethyl diallyl ammonium chloride (DMDAAC), and the crosslinking agent for the polymerization reaction is N , N -methylene-bis-acrylamide (MBA). Using H-NMR spectrometry, the molecular structure of the polymer gel micro spheres was characterized. Effect of the molar ratio of the monomers and the concentrations of the crosslinking agent and emulsifier on the size distribution and plugging performance of the polymer gel spheres was investigated. The optimum molar ratio of the monomers for the polymerization was determined as: DAM∶AMPS∶DMDAAC = 7∶1∶2, the optimum mass concentration of MBA (based on the total mass of the monomers) was 0.2%, and the optimum concentration of the emulsifier (based on the total mass of the monomers) was 3%. The average particle size of the polymer gel micro spheres is about 22 μm. The plugging capacity of the polymer gel micro spheres was tested in oil based muds, and it was found that the polymer gel micro spheres are suitable very well to use in the oil based muds. At 150 ℃, the polymer gel micro spheres can effectively plug fractures of 5-150 μm, a plugging performance better than the combination of oxidized asphalt and fine calcium carbonate. The test results show that the zwitterionic polymer gel micro spheres are a high-performance millimeter-sized plugging agent with good field application potential.