耐盐胶乳水泥浆体系的室内研究

An experimental study of a salt-tolerant latex cement slurry system

胶乳水泥浆体系已广泛应用于大位移井、分支井、大斜度井、调整井和小井眼井等疑难井的固井,用以提高水泥浆的防气窜和控制失水能力,同时改善水泥石的胶结性能、韧性和防腐蚀能力。但是,由于盐的存在会使胶乳双电层的zeta电位降低,从而破坏胶乳的稳定性,导致胶乳在盐水中发生絮凝,因而限制了其在含盐岩层(盐层、盐膏层、盐水层)和水敏地层等复杂井的使用。针对这一难题,实验室研发并在国内首报了一种耐盐胶乳水泥浆体系,采用动态光散射、Zeta电位仪、差示扫描热分析仪以及热重分析仪对其粒径、稳定性、玻璃化温度以及热稳定性进行了分析描述;还开发了配套的耐盐缓凝剂以及降失水剂,并研究了盐含量为15%BWOW时耐盐胶乳水泥浆体系的性能。对该耐盐胶乳水泥浆体系性能的研究结果表明:①能耐饱和氯化钙溶液、饱和盐水以及耐250℃高温;②具有流变性好、失水量小、防气窜等优点;③可满足含盐岩层井和含水敏地层井固井要求。

The latex cement slurry has been widely used in the cementing of extended-reach wells,multi-lateral wells,high-angle deviated wells,adjustment wells,and slim wells,to reduce gas channeling and fluid loss and to improve the bonding property,ductility,and corrosion control performance of the cement stones.But if salt is introduced into the latex,the zeta potential of the electric double layers will be lowered,the latex stability will be destroyed,and latex flocculation will take place inside the salt water,as a result,the latex application will be limited in salt beds,salt-gypsum beds,deep aquifer,and water-sensitive formations.For this,a salt-tolerant latex cement slurry system is developed in laboratory and reported for the first time in China.The grain size,stability and vitrification,and thermal stability of this latex cement slurry are analyzed and described by the Dynamic Light Scattering(DLS),the Zeta Potential Analyzer,the Differential Scanning Calorimeter(DSC),and the Thermogravimetric Analyzer(TGA).The salt-tolerant latex cement slurries,composed of API G class cement,latex L,defoamer DF,dispersant D,retarder R,fluid-loss control agent F,are prepared successfully.The properties of the salt-tolerant latex cement slurry and the subsequent set cements are also investigated.The results indicate the latex L is compatible with the saturated solutions of calcium chloride and sodium chloride and does not thermally degenerate until 250℃.The slurries prepared of the 17%BWOC latex,15% BWOW aqueous solutions of sodium chloride and subsequent set cements can exhibit many advantages such as good rheology,low fluid-loss control,anti-migration and meliorated toughness.In the presence of other additives like fluid-loss control agent,set retarder etc.,this cement slurry system can be tailored to meet the requirements of cementing for the wells with salt-gypsum beds or water-sensitive beds.