酰胺改性碳纳米管对固井水泥浆性能的影响

为提高无分散剂条件下碳纳米管在固井水泥浆中的分散性，对碳纳米管表面进行酰胺化改性并进行了红外表征，通过水泥石中不同区域导电性的差异程度来评价其分散效果，同时考察了酰胺化碳纳米管对固井水泥力学性能和综合性能的影响。研究表明，碳纳米管分散剂（阿拉伯胶）加量大时对水泥浆存在缓凝、沉降等消极影响，使得水泥石强度降低51.4%，上下密度差达1.309 g/cm3；对碳纳米管进行酰胺改性后，无分散剂条件下可实现碳纳米管在水泥浆中的均匀分散，空间导电率方差与未改性相比降低为原来的0.1%以下；改性材料的水润湿性更强，掺入0.06%酰胺化碳纳米管可使固井水泥浆的抗压强度、抗折强度、抗拉强度、抗冲击功分别提高33%、30%、61%、33%。酰胺化碳纳米管对固井水泥浆的稠化、析水、失水等综合性能均无影响，同时可分别降低水泥石渗透率和孔隙度达22.9%和25.5%。结果表明，酰胺化碳纳米管在无分散剂条件下能够均匀分散于固井水泥浆中，并且提高其力学性能，具有一定的应用前景。 

Effects of Amide-modified CNTs on Properties of Cement Slurry

To understand the factors affecting the dispersibility of the carbon nanotubes (CNTs) in cement slurries containing no dispersants, the CNTs was amide-modified on its surface and the modification was characterized by IR. The dispersibility of CNTs was evaluated through the electro-conductivity difference in different zones of set cement, and the effects of the amidated CNTs on the mechanical property and the overall performance of the set cement were also evaluated. The studies showed that dispersant for CNTs (gum Arabic) at high concentrations rendered negative effects on the retardation and settling properties of cement slurries, reducing the strength of the set cement by 51.4% and the density difference between the top and the bottom of a cement column was as high as 1.309 g/cm3. Amidated CNTs can be evenly dispersed in a cement slurry with no dispersant. CNTs after amidation had its spatial conductivity variance reduced by at least 1000 times. The amidated CNTs had stronger water wettability. A cement slurry treated with 0.06% amidated CNTs had its compressive strength, rupture strength, tensile strength and impact resistance increased by 33%, 30%, 61% and 33%, respectively. The amidated CNTs had no effect on the thickening, free water and filtration rate of cement slurries. It reduced the permeability and porosity of a set cement by 22.9% and 25.5% respectively. It was concluded that in cement slurries with no dispersants, the amidated CNTs can be evenly dispersed and can improve the mechanical performance of the cement slurries. This property renders the amidated CNTs application prospects in well cementing.