常用外掺料对G级油井水泥体积稳定性及力学性能的影响

Effects of common admixtures on volume stability and mechanical properties of class G oil well cement slurry

针对G级油井水泥浆体体积收缩问题,对比研究了两种常用外掺料(矿渣和石英粉)对水泥浆体体积稳定性及力学性能的影响,并利用等温量热仪(ICC)、X射线衍射仪(XRD)、压汞仪(MIP)和扫描电镜(SEM)分别测试了两种外掺料对水泥水化放热速率,水泥水化产物、孔结构及水泥石微观形貌的影响。结果表明:80℃下水泥净浆体积收缩主要发生在水化早期,对应水泥石早期抗压强度、抗折强度增长迅速;掺入30%比表面积为340m^2/kg的矿渣部分改善浆体体积收缩,150 d线收缩率较净浆减小32%,早期抗压强度、抗折强度减小,后期强度增大并超过净浆;掺入30%比表面积为710m^2/kg的石英粉加剧了浆体体积收缩,150d线收缩率较净浆增大40%,早期抗压强度、抗折强度远低于净浆及掺30%矿渣水泥。长期水养后部分超细SiO2参与反应,加之细颗粒的填充作用使其150 d力学强度超过净浆及掺30%矿渣水泥,即水泥石力学强度不仅与外掺料活性有关,还与其粒径分布和养护龄期密切相关。

Based on shrinkage for class G oil well cement slurry in using process,effects of two common admixtures(slag and quartz powder)on volume stability and mechanical properties of class G oil well cement slurry were contrasted,and effects of two common admixtures on early exothermic rate of hydration,hydration products,pore structure and microstructure were characterized by isothermal conduction calorimetery(ICC),X-ray diffraction analyzer(XRD),mercury intrusion porosimetry(MIP)and scanning electron microscope(SEM).The results show that at the temperature of 80℃,the main shrinkage of class G oil well cement slurry occurred during early hydration period,and the early compression strength,flexural strength of cement paste increased rapidly;The volume shrinkage of cement slurry with 30%slag(340 m^2/kg)has reduced,the linear shrinkage(150 d)reduced by 32%.the early compression strength,flexural strength of cement paste with 30%slag decreased,but the last strength increased even more than the strength of pure cement paste;The volume shrinkage of cement slurry with 30%quartz powder(710 m^2/kg)increased,the linear shrinkage(150 d)increased by 40%and the early compression strength,flexural strength of cement paste with 30%quartz powder lower than that of pure cement paste and cement paste with 30%slag.After long term water-bath curing,part of super fine SiO2 involved in the reaction,and favorable grain composition make the strength(150 d)of cement paste with 30%quartz powder higher than that of pure cement paste and cement paste with 30%slag,so the strength of cement paste was influenced by not only the acticity of admixtures but also the particle size and curing age.