Y油田盐膏层固井水泥浆及前置液性能评价

Performance evaluation of cementing slurry and preflush for salt gypsum formation in Y Oilfield

针对伊拉克Y油田盐膏层在钻进中存在的地层塑性、井壁失稳及水泥浆与钻井液配性差等问题,室内结合现场数据开展了水泥浆及配套工作液构建及优化,进行了水泥浆抗盐能力分析,对盐膏层高密度水泥浆体系的加重方式、流变性、力学性及其配套的前置液体系配伍性、抗污染能力等进行了评价。结果显示,15%NaCl溶液作为盐水基液,配置水泥浆不仅满足应用性能,还具有良好抗盐能力;确定加重剂A(复合锰矿粉类)、B(超细铁矿粉)复配比例为3∶8,得到高密度水泥浆具有良好流变性和低失水性,且在20MPa围压下,水泥石抗压强度可达30.7MPa,满足盐膏层固井要求;确定加重剂B(超细铁矿粉)、C(重晶石)复配比例为1∶1,获得冲洗液具有良好的高温稳定性、抗污染能力,同时可与水泥浆、钻井液等配伍。研究结果不仅确定了适用于伊拉克Y油田盐膏层作业的水泥浆体系,也可为高性能水泥浆设计提供思路。

In view of the problems of formation plasticity,wellbore instability and poor compatibility of cement slurry and drilling fluid in the drilling of salt gypsum layer in Iraq Y Oilfield,the construction and optimization of cement slurry and supporting working fluid were carried out indoors in combination with field data,the salt resistance of cement slurry was analyzed,and the weighting method,rheological property,mechanical property of high-density cement slurry system in the salt gypsum layer and the compatibility and pollution resistance of supporting preflush system were evaluated.The results show that 15%NaCl solution,as the salt water base fluid,can not only meet the application performance,but also have good salt resistance;The compound proportion of weighting agents A(composite manganese ore powder)and B(ultra-fine iron ore powder)is determined to be 3∶8,and the high-density cement slurry has good rheology and low water loss,and the compressive strength of cement paste can reach 30.7MPa under 20MPa confining pressure,meeting the requirements of well cementation in the salt gypsum layer;The compound proportion of weighting agent B(superfine iron ore powder)and C(barite)is 1∶1.The obtained flushing fluid has good high-temperature stability,anti pollution ability,and can be compatible with cement slurry,drilling fluid,etc.The research results not only determine the cement slurry system suitable for the salt gypsum layer operation in Iraq Y Oilfield,but also provide ideas for the design of high-performance cement slurry.