纳米液硅防窜水泥浆体系性能研究及应用

Performance Research and Application of Liquid Nano-silica Anti-channeling Cement Slurry System

在石油工程领域,近几年国内新兴起纳米液硅水泥浆体系。系统性地研究了该水泥浆体系以流态、塑态、固态存在时的各项关键性能。纳米液硅颗粒尺度小,比表面积大,具有增黏提切作用,水泥浆体系以流态存在时比普通水泥浆体系具有更好的基础性能,幂律指数为0.69,稠度系数为0.45 Pa·s^(n),API失水36 mL,无自由液,无沉降现象。纳米液硅颗粒的堵塞作用与促凝作用提升水泥浆体系向塑态转变时的防窜性能,气窜因子SPN值为1.3,比普通水泥浆体系低62.9%,静胶凝强度由48 Pa发展至240 Pa的时间为7 min,模拟实验中无窜流现象发生。纳米液硅颗粒能增加水泥石致密性,并参与水泥水化反应修复水泥石内部微裂隙、微缺陷,固态水泥石力学性能也明显优于普通水泥石。纳米液硅加量15%,龄期7 d时的水泥石弹性模量为8.3 GPa,降低幅度为38.9%,水泥石强度为53 MPa,提高幅度为35.9%,渗透率为0.007×10^(-3)μm^(2),比普通水泥石降低90.9%。纳米颗粒具有限位支撑作用,纳米液硅水泥浆体系转变为塑态、固态后具有更低的水化收缩率,分别为1.26%、0.34%。最后,介绍了纳米液硅水泥浆体系在顺北油田的应用情况,累计应用153井次,平均固井优良率为91.7%,主要解决了产层套管固井的桑塔木高压水层与辉绿岩盐水层窜流难题。

Liquid nano-silica anti-channeling cement slurry system is widely applied by Sinopec recent years.The key properties of the slurry system in the presence of fluid,plastic and solid state are systematically studied.Experiments show that,the liquid nano-silica particle size is small and the specific surface area is large.The cement slurry system has better basic properties than the ordinary cement slurry system in the presence of flow state,such as,power-law index 0.69,consistency coefficient 0.45 Pa·s^(n),API water loss 36 mL,no free liquid,no sedimentation.Blocking and procoagulant effect of nano liquid-silica particles can improve anti-channeling performance of cement slurry system during plastic transformation.The SPN value of gas channeling factor is 1.3,which is 62.9%lower than that of ordinary cement slurry system.The time of static gel strength developing from 48 Pa to 240 Pa is 7 min.There is no channeling phenomenon in the simulation experiment.Liquid nano-silica particles can increase the compactness of cement stone,and repair the internal micro cracks and micro defects of cement stone by participating in cement hydration reaction.The mechanical properties of solid cement stone are also significantly better than ordinary cement stone.When the dosage of liquid nano silica is 15%and the age is 7 d,the elastic modulus of cement is 8.3 GPa,the decrease is 38.9%,the strength of cement is 53 MPa,the increase is 35.9%,and the permeability is 0.007×10^(-3)μm^(2),which is 90.9%lower than that of ordinary cement.Nanoparticles have the role of limiting support.The nano-liquid silicon cement slurry system has lower hydration shrinkage after being transformed into plastic and solid.The plastic state shrinkage and solid state shrinkage are 1.26%,0.34%lower than that of ordinary cement slurry.Finally,the application of liquid nano-silica cement slurry system in Shunbei Oilfield is introduced.The cumulative application of more than 150 wells,the average cementing excellent rate is 91.7%,which mainly solves the channeling problem of Sangtamu high pressure water layer and diabase salt water layer in production casing cementing.