碳纳米管改性水泥石力学性能研究

随着非常规油气的勘探开发,超深井、复杂井、页岩气井等对固井质量的要求越来越高,现有水泥基材料性能已经不能满足要求,需要探索新型材料在水泥基材料中的应用以及对水泥石的性能改造。从碳纳米管自身的特点出发,制备稳定性较好的碳纳米管分散液,通过水泥石抗压强度、抗折强度测试、单轴三轴力学性能实验以及微观结构测试对碳纳米管的加量范围、分散效果进行了讨论,分析碳纳米管对水泥石力学性能的影响规律。实验结果表明,0.05%~0.1%碳纳米管加量能够提高水泥石的抗压、抗折性能,并且随着龄期的增长其增强效果更加明显;碳纳米管能够降低水泥石的弹性模量,同时增大塑性形变,使水泥石韧性增加;碳纳米管对微观结构的增强增韧机理表现为拨出、桥联、纳米诱导效应和网状填充效应,经过分散的碳纳米管与基体的相容性较好。 

Study on Mechanical Performance of Set Cement Modified with CNT

The development of unconventional petroleum is demanding more and more rigorous requirements on the job quality of cementing ultra-deep wells, complex wells and shale gas wells. Most of the cementing materials cannot satisfy these requirements and study should be done to find out new cementing material for field application or improvement of the performance of set cement. A carbon nanotube (CNT) dispersion has been developed with good stability for use in cement slurry. Laboratory experiments on cement slurries treated with the developed CNT, such as compressive strength test, flexural strength test, uniaxial/triaxial mechanical properties test and micro structure determination, were conducted to determine the treatment concentration of the CNT, to understand the dispersing effect of the CNT, and to analyze how CNT affects the mechanical property of set cement. It was found, through these experiments, that addition of 0.05%-0.1% CNT in cement slurry enhanced the compressive strength and flexural strength of set cement, and the effects of CNT on the two strengths were increasing with time. CNT was found to be able to reduce the elastic modulus of set cement and to improve the toughness of set cement by increasing its plastic deformation. Mechanisms in which the CNT increases the strength and toughness of the micro structure of set cement are pulling, bridging, nano-inductive effect and network filling effect. Dispersed CNT has good compatibility with cement slurry.