Collapse strength analysis of casing design using finite element method

Accurately predicting the ultimate collapse strength is very important in the design of casings for the oil and gas industry. For an infinitely long thick walled casing subjected to external pressure, a finite element model has been proposed to achieve a better understanding of the ultimate collapse strength of casing. Careful comparison with a series of full-scale experiments has been conducted to verify the accuracy and reliability of the finite element model. In addition, several current predictive equations for casing design have been assessed using those available test data. The validation proves that, if the material behaviour and imperfection variables are known, the ultimate collapse strength of casing can be predicted to a satisfactory degree of accuracy. Major factors, which affect the collapse strength of casing, were studied and their effects on the collapse strength of casing were summarized. Regression analysis has been conducted on the basis of finite element predictions and a new design equation for casing collapse is presented.