An Experimental and Numerical Approach to the Prediction of Collapse Resistance for Expandable Tubulars

Abstract

Abstract Expandable tubular technology is an effective method for saving on the costs of well drilling and completion. There are many applications for casing repair and slim hole casing design. The most essential aspect of post-expansion expandable tubular (EXP-T) is collapse resistance, which is affected by not only the expanded pipe properties, but also the axial restraint caused by sticking pipe in wells. This paper discusses the effect of expansion condition on the collapse and the prediction methods of the post-expansion collapse resistance by conventional formulas and numerical simulation. The test pipes for EXP-T were expanded at the various expansion ratios with/without axial restraint. Using the post-expansion pipes, full-scale collapse tests were performed. FEA (Finite Element Analysis) for pipe collapse considering the pipe geometries and the mechanical property was also carried out for predicting the collapse pressure of EXP-T after expansion. In addition, the accuracy of conventional formulas and FEM models for collapse prediction was inspected by comparing the collapse test results. These results reveal potential to improve the collapse resistance of the pipe expanded under the axial restraint. Good agreements were found between the collapse test results and the predictions by FEA are drawn.