一种大温差耐温耐盐缓凝剂的合成及性能评价

Synthesis and Performance Evaluation of a Temperature Resistance and Salt Tolerance Retarder for Large Temperature Difference Cementing

以2-丙烯酰胺基-2-甲基丙磺酸（AMPS）、丙烯酸（AA）、二烯丙基二甲基氯化铵（DMDAAC）为单体,改性蒙脱土为活性填料合成了一种有机-无机复合型大温差缓凝剂（PMC-180）。利用FTIR、XRD和TG对产物进行了结构表征,并对其应用性能进行了评价。结果表明：PMC-180具有插层剥离复合结构,初始热解温度为267.27℃。含PMC-180的水泥浆在90～180℃耐温缓凝性能和抗盐性能良好,初始稠度低于30 Bc,稠化时间可调,曲线平稳无＂鼓包＂等异常现象;含PMC-180的24 h水泥石低温强度高于14 MPa,满足长封固段固井要求。PMC-180的缓凝机理及大温差适应机理为：PMC-180通过吸附屏蔽及络合抑制作用延缓Ca（OH）_2晶核、晶体生长;PMC-180片层间距随温变化及阴阳离子竞争吸附减缓低温过渡吸附,使PMC-180具有良好的大温差适应性。

A polymer/inorganic composite retarder（PMC-180） was prepared by in-situ intercalated polymerization method using 2-crylamido-2-methylpropanesulfonic acid（AMPS）, acrylic acid（AA） and diallyl dimethyl ammonium chloride（DMDAAC） as monomers, modified montmorillonite as active polymerization filler. The as-prepared retarder was characterized by FTIR, XRD and TG. And its application performance was evaluated. The results showed that PMC-180 had an intercalation and exfoliation composite structure with an initial pyrolysis temperature of 267.27 ℃. The cement paste containing PMC-180 exhibited good retarding property, salt tolerance and temperature resistance under 90～180 ℃. The initial consistency was lower than 30 Bc and the thickening time could be regulated effectively. Furthermore, the thickening curves of different kinds of cement paste were stable without abnormal phenomenon such as bulging. The compressive strength of cement stone containing PMC-180 was greater than 14 MPa at low temperature, which could be applied to long sealing and large temperature range cementing operation. The retarding mechanism and temperature adaptation mechanism of PMC-180 were as follows： when PMC-180 was adsorbed on the surface of cement particles, the hydration adsorption and complexation reaction between PMC-180 and Ca2＋ inhibited Ca（OH）2 crystal nucleus or crystal growth.Both interlayer spacing change with temperature and competition adsorption between cations and anions in PMC-180 could effectively decrease excessive adsorption of the retarder at low temperature, which made PMC-180 have good adaptability of large temperature difference.