胶乳对水泥石三轴力学形变能力的作用

Improvement of latex on mechanical deformation capability of cement sheath under triaxial loading condition

针对套管、水泥环、地层三者间形变不协调而引起油气井生产后期层间封隔失效的问题,采用美国GCTS公司三轴岩石力学测试系统RTR-100,准确地测定了在三轴应力直接加载及三轴应力多周循环两种加载方式下水泥石的力学形变能力。实验结果表明,水泥浆中添加一定量的SBR胶乳,在降低油井水泥石抗压强度的同时增大了油井水泥石在低应力作用下的弹性形变和在高应力下的塑性形变,提高水泥石抗冲击破坏的能力。

The deformation of cement sheath is often inconsonant with that of casing and formation. The mechanical deformation capability of cement sheath was accurately measured under the two conditions of triaxial stress directly loading and triaxial stress cycle loading by the triaxial rock mechanical test system RTR-100 of American GCTS Corporation. Experiment results showed that some doze of SBR latex could improve the mechanical deformation capability of cement sheath and decrease the compressive strength of that. The elastic deformation capability at low stress and the plastic deformation capability at high stress could also increase. Then the impact resistance strength could increase. The improvement of mechanical deformation capability of cement sheath and its accurate measurement are favorable for the coupling design of casing-cement sheath-formation deformation and ensuring the integrity and zonel sealing property of cement sheath.