氧化石墨油井水泥基复合材料的力学性能研究

Mechanical Properties of Graphite Oxide Oil Well Cement-based Composite Material

针对油井水泥石易脆裂而导致油气井水泥环层间封隔失效这一问题,实验研究了氧化石墨对油井水泥石力学性能的增强效果。利用SEM、EDS和XRD等手段对氧化石墨增强水泥石进行了表征,并探讨了氧化石墨增强机理。实验结果表明:氧化石墨可显著增强水泥石力学性能,氧化石墨掺量为0.05%时,增强水泥石的28 d抗压、抗折和劈裂拉伸强度较纯水泥石分别提高68.63%、17.44%和159.12%;氧化石墨对水泥浆的应用性能无不良影响,反而有助于改善水泥浆的沉降稳定性并降低水泥浆失水量。机理分析结果表明:水泥石在受外力破坏时,氧化石墨层内、层间均出现损伤;一方面氧化石墨层内破坏时其化学键必然断裂而耗能,另一方面氧化石墨层间剥离时需克服层间作用力而耗能,氧化石墨主要通过上述两方面的作用增强水泥石力学性能。研究结果可为解决油井水泥石易脆裂问题提供理论参考。

The effect of graphite oxide on the mechanical properties of oil well cement was experimentally studied, aiming at the zonal isolation failure in oil and gas wells due to the brittleness of oil well cement stone. SEM, EDS and XRD were used to characterize the graphite oxide reinforced cement, and the strengthening mechanism of graphite oxide was also discussed. The experimental results showed that graphite oxide could significantly enhance the mechanical properties of cement stone, and the 28 d compressive, flexural and splitting tensile strength of cement stone containing 0.05 % graphite oxide were increased by 68.63% , 17.44% and 159.12% respectively, compared to the control samples; graphite oxide had no bad effect on the application properties of cement slurry, but was helpful to improve the stability of cement slurry and reduce the fluid loss. Mechanism analysis results showed that the inter-layer and intra-layer of graphite oxide were both damaged, when the cement stone was destroyed force; on the one hand, when damage occured within graphite oxide layer, chemical bonds by external of graphite oxide must have been broken, leading to a large amount of energy consumption, on the other hand, the force between the layers of graphite oxide must have been overcome when interlaminar peeling happened, which would lead large amounts of energy consumption as well, the mechanical properties of the cement stone were mainly enhanced by this two aspects. The research results can provide a theoretical reference for solving the brittle fracture of oil well cement stone.