改性碳纳米管对水泥石力学性能的影响

为满足储气库和高压油气井对水泥石力学性能的要求,优选了改性碳纳米管TNIMH4(—OH)和TNIMC6(—COOH)。考察了他们对水泥浆综合性能及水泥石力学性能的影响。通过抗压强度实验可知,掺入0.01%的TNIMH4能使水泥石强度增加4.32%;掺加0.07%的TNIMC6能使水泥石强度增加19.18%,当TNIMC6与TNIMH4加量相同时,添加TNIMC6的水泥石强度大于添加TNIMH4的水泥石强度。通过三轴岩石力学实验可知,添加TNIMC6的水泥石的三轴抗压强度比空白组增加了41.21%,弹性模量由3 692.5 MPa增加到4 366.5 MPa。通过扫描电镜观察发现,低加量的碳纳米管能在水泥石中较好地分散,随着碳纳米管含量的增加,碳纳米管在水泥石中开始出现团聚现象,增大了水泥石的不均质性,影响水泥石的强度。

Effect of Modified Carbon Nanotube on Mechanical Property of Set Cement

Abstract Two modified carbon nanotubes, TNIMH4(—OH) and TNIMC6(—COOH) were selected to satisfy the needs of natural gas storage and high pressure oil and gas well for better mechanical performance of set cement. Laboratory experiments showed that cement slurry treated with 0.01% TNIMH4 had its compressive strength increased by 4.32%, cement slurry with 0.07% TNIMC6 had its compressive strength increased by 19.18%. At the same treatment, the compressive strength of cement slurry treated with TNIMC6 was greater than that of cement slurry treated with TNIMH4. Tri-axial compressive strength experiments showed that the tri-axial compressive strength of the cement slurry treated with TNIMC6 was 41.21% greater than that of the blank cement slurry., and the elastic modulus of the cement slurry was increased from 3,692.5 MPa to 4,366.5 MPa. SEM observation showed that the nanotubes at low concentrations were dispersed evenly in the set cement, and began to agglomerate at increasing concentrations, which in turn aggravated the heterogeneity of, and hence weakened the strength of the set cement.