摘要
聚丙烯酰胺(PAM)体系水凝胶是采油中常用的堵水调剖试剂,无机微纳颗粒的引入常用于提升PAM体系水凝胶的机械性能,但其引入对凝胶耐温性能的影响则鲜有讨论.为了探索无机微纳颗粒粒径对凝胶堵剂耐温性能的影响,引入 5 种粒径分别为 15 nm、30 nm、100 nm、1 μm、10 μm的SiO2 微纳颗粒并研究其对PAM凝胶高温老化前后的弹性模量、黏性模量和拉伸强度等性质的影响.结果表明,随着SiO2 粒径的减小,凝胶耐温性能呈先增加后减小的趋势;SiO2 颗粒粒径为 30 nm时,凝胶的强度和耐温性能最好;与不含SiO2 颗粒的凝胶相比,高温老化前含粒径30 nm SiO2 颗粒的凝胶的储能模量高约2.1 倍、拉伸强度高约4.6 倍、同等应变下压缩所需应力更高;高温老化后含粒径30 nm SiO2 颗粒的凝胶储能模量高约 1.9 倍、拉伸强度高约 3.3 倍、同等应变下压缩所需应力更高.SEM扫描电镜结果表明,SiO2 颗粒粒径减小、比表面积增大,单位体积凝胶中微纳颗粒表面羟基与PAM中酰胺基形成的氢键链接越多,因此强度越高,耐温性随之提升;但粒径过小时颗粒分散性差,易于团聚,会使得上述效应减弱,因此凝胶机械强度和耐温性能下降.
Abstract
Polyacrylamide(PAM)system hydrogels are commonly used as water plugging and conditioning reagents in oil recovery.In order to explore the effect of the particle size of inorganic micro-nano particles on the temperature resistance of gel plugging agent,five kinds of SiO2 micro-nano particles with sizes of 15 nm,30 nm,100 nm,1 μm,and 10 μm are respectively added,and their effect on elastic modulus,viscous modulus and tensile strength of PAM gels before and after the high-temperature aging are evaluated.Results show that with the decreasing particle size of SiO2,the temperature resistance of the gels increases firstly and decreases then.Both the strength and temperature resistance of the gels reach the best when SiO2 particle size is 30 nm.Compared with the gels without SiO2 particles,before high-temperature aging,the storage modulus of the gels containing 30 nm SiO2 particles is about 2.1 times higher,and the tensile strength is about 4.6 times higher,and the stress required for compression is higher under the same strain;After high-temperature aging,the energy storage modulus of the gels containing 30 nm SiO2 particles is about 1.9 times higher,the tensile strength is about 3.3 times higher,and the stress required for compression is higher under the same strain.SEM results show that as the particle size of SiO2 particles decreases,their specific surface area becomes larger,and more hydrogen bonding links form between hydroxyl groups on the surface of the nanoparticles per unit volume of the gels and amide group of PAM.Therefore,the strength is higher,and the temperature resistance is improved.But if the size is too small,the dispersion of particles is poor and it is easy to agglomerate,which will weaken the above effects,and lead to drops in mechanical strength and temperature resistance of the gels.
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