Worn-casing burst strength after cement sheath defect

Casing wear and cementing defect are the inevitable phenomenon during drilling process. The similarity criterion is applied to design the similar model of the worn-casing. The combination experiments were executed for different cementing quality defects and different worn-casings. Then the result of the experiment and the finite element analysis are compared to study the model casing burst strength. Extending the model casing to prototype, finite element method is used to calculate the internal pressure strength of the cement-casing-formation system at different deficiency scope of cement sheath and different wear loss. The results show that the cement sheath would decrease the internal pressure strength of the casing, and the smaller the deficiency scope is, the greater the stress concentration is.