新型两性离子固井降失水剂的合成与性能评价

以丙烯酰胺（AM）、丙烯酸（AA）、2-丙烯酰胺-2-甲基丙磺酸和一种新型阳离子单体（X）为原料，采用自由基水溶液聚合法，通过正交实验，优选出最佳合成工艺，合成出一种新型耐盐、抗高温、适用温度范围广的降失水剂TSM-1。用红外光谱、核磁共振和热失重分析对其进行表征，并对添加降失水剂TSM-1水泥浆体系的综合性能进行评价。实验结果表明，聚合物TSM-1中含有4种单体的特征官能团，热稳定性高。降失水剂TSM-1缓凝效果弱，不影响水泥石强度，TSM-1与不同类型水泥和固井缓凝剂配伍好，综合性能优异。由于在聚合物分子结构中引入一种功能性阳离子单体，合成的降失水剂TSM-1有较宽的适用范围，最高可达200℃，可控制饱和盐水水泥浆失水量在50 mL以内，满足固井施工要求。通过化学分析、扫描电镜等方法得出降失水剂作用机理为:两性离子通过多点吸附作用牢牢吸附在水泥颗粒表面，形成一层吸附膜，在失水压差下，吸附膜被挤压、充填于水泥颗粒孔隙中，堵塞失水通道、降低泥饼渗透率，从而控制失水量。 

Synthesis and Evaluation of a New Amphoteric Filter Loss Reducer for Cement Slurry

A salt-resistant, high temperature filter loss reducer TSM-1 has been developed through radical aqueous solution polymerization, with acrylamide (AM), acrylic acid (AA), 2-acrylamide-2-methyl propane sulfonic acid and a new cationic monomer (X) as raw materials. The synthesis process was optimized through orthogonal experiment. TSM-1 was characterized with IR spectrometry, NMR and thermogravimetric analysis, and the overall properties of cement slurries treated with TSM-1 were evaluated. Laboratory experimental results show that the molecules of TSM-1 have the characteristic functional groups of the four monomers, rendering TSM-1 good thermal stability. TSM-1 has weak retarding effects, meaning that it does not affect the strength of set cement. TSM-1 is compatible very well with retarding agents commonly used in oil well cement. The introduction of the functional cationic monomer into the molecules of TSM-1 renders TSM-1 a wide working temperature range; the highest temperature under which TSM-1 works properly is 200℃. With TSM-1, the filtration rate of cement slurry formulated with saturated saltwater can be controlled within 50 mL, satisfying the needs for well cementing. Chemical analysis and SEM analysis of TSM-1 indicate that the mechanisms under which TSM-1 functions are that the amphoteric ions are firmly adsorbed on the surface of cement particles through multipoint adsorption, thereby forming a layer of adsorption film. Under the filtration pressure, the adsorption film is pressed and fills into the spaces between cement particles. As such, the water loss channel is plugged and the permeability of mud cakes reduced, thereby reducing water loss of cement slurry.