改性乙烯醋酸乙烯酯共聚物对水泥浆性能的影响

Effect of Modified Ethylene Vinyl Acetate Copolymer on the Property of Cement Slurry

岳跃展 杨远光 杨生荣 张凯敏 张 亮

YUE Yuezhan YANG Yuangang YANG Shengrong ZHANG Kaimin ZHANG Liang

针对水泥环脆性较高， 在固井后的施工作业中其完整性易遭受破坏的问题， 将用太古油改性的 EVA （乙烯醋酸乙烯酯共聚物） 作为增韧材料加入油井水泥中， 研究了其对油井水泥浆体系常规性能和力学性能的影响， 分析了其对水泥石力学特性的影响机理。结果表明， 改性 EVA与水泥浆的相容性较好， 其对浆体的流动性、 失水量影响较小， 水泥浆稠化时间随改性 EVA掺量增加而延长； 改性 EVA对水泥石抗压强度影响较小， 但能提高水泥石的抗折强度和韧性， 当改性 EVA加量为 3%时， 水泥石 75℃养护 3 d的抗折强度提高 4.4%， 压折比减小 28.0%，掺量为 4%时， 水泥石弹性模量降低 39.5%。改性 EVA水解产物和水泥水化产物相结合， 生成的晶体和脱水聚合物使水泥石内部结构更加致密， 减小或消除了水泥石内应力集中， 阻止了裂缝扩展， 改善了水泥石的力学特性。图6表3参13

Aiming at the problem that cement sheath integrity was easily broken during construction because of its high brittleness， toughen cement slurry was developed by ethylene vinyl acetate（EVA）copolymer modified by Turker red oil. The effect of modified EVA on general and mechanical properties of cement slurry was studied and the effect mechanism on the mechanical properties of set cement was analyzed. The results showed that modified EVA had good compatibility with cement slurry，its influence on the fluidity and water loss of slurry was less. The thickening time of cement slurry prolonged with increasing modified EVA dosage. Modified EVA had slight impact on the compressive strength of set cement，but it could improve the flexural strength and toughness of set cement. The flexural strength of set cement improved by 4.4% after curing 3 days at 75℃ and the ratio of compressive strength to flexural strength decreased 28.0% when the dosage of modified EVA was 3%. When the dosage of modified EVA was 4%，the elastic modulus of set cement decreased 39.5%. Crystal and polymer generated after hydrolysate of modified EVA combined with hydration products of cement，which made the internal structure of set cement become denser，decreased or removed the stress concentration，prevented crack propagation，and improved the mechanics characteristic of set cement.

10.19346./j.cnki.1000-4092.2017.01.004