高密度水泥浆高温沉降稳定调控热增黏聚合物研制与性能

在深井/超深井固井过程中，井底高温加剧了水泥浆中颗粒的布朗运动、降低了水泥浆内部黏滞力，高密度水泥浆更易发生沉降失稳甚至严重分层，影响固井质量和安全。现有改善高温高密度水泥浆稳定性方法存在着"低温增稠、高温变稀"缺陷，为此，在丙烯酰胺（AM）、2-丙烯酰胺基-2-甲基丙磺酸（AMPS）共聚基础上引入耐高温N，N-二甲基丙烯酰胺（DMAA）单体、憎水单体（HCZW-50），采用水溶液自由基共聚法，合成出具有优秀热增黏特性的新型聚合物（TV-1），利用红外光谱、核磁共振、热重分析、凝胶渗透色谱、冷冻扫描电镜等分析了TV-1的结构、热增黏机理等，评价了TV-1对高密度水泥浆高温沉降稳定性的调控规律。研究结果表明：TV-1聚合物耐温性能优异，在20~150℃温度范围内，表观黏度随温度的升高显著增加，其独特的热增黏特性有助于防止高温高密度水泥浆沉降，在155℃下TV-1可将高密度水泥浆上、下密度差控制在0.03 g/cm³之内，为高温高密度水泥浆沉降稳定性调控提供了一种新方法，有利于提高深井/超深井固井质量，降低固井风险。

Development and performance of thermo-viscosifying polymer for high temperature sedimentation control of high density cement slurry

In the cementing process of deep/ultra-deep well, the bottom-hole high temperature intensifies the Brownian motion of particles in the cement slurry and reduces the viscous force inside the cement slurry. High-density cement slurry is more prone to settlement instability or even serious stratification, which affects cementing quality and safety. The existing methods for improving the stability of high-temperature and high-density cement slurry have the defect of "thickening at low temperature and thinning at high temperature". For this reason, this study introduces high temperature resistant N,N-Dimethylacrylamide(DMAA)monomer, hydrophobic monomer (HCZW-50)based on the copolymerization of acrylamide (AM) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS), and synthesizes a new type of polymer with excellent thermoviscosifying properties (TV-1)using the water solution free radical copolymerization method. Using infrared spectroscopy, nuclear magnetic resonance, thermogravimetric analysis, gel permeation chromatography, and freeze scanning electron microscopy, this paper analyzes the structure and thermoviscosifying mechanism of TV-1, and evaluates the control law of TV-1 to the stability of high temperature sedimentation of high-density cement slurry. The results show that TV-1 polymer has excellent temperature resistance; in the temperature range of 20-150 ℃, the apparent viscosity increases significantly with the increase of temperature. Its unique thermoviscosifying property helps prevent the settlement of high-temperature high-density cement slurry. At 155 ℃, TV-1 can control the difference of density of high-density cement slurry within 0.03 g/cm³, which provides a new method for adjusting the settlement stability of high-temperature and high-density cement slurry, which is beneficial to improve the cementing quality of deep/ultra-deep well and reduce cementing risks.