Collapse Behavior of Casings: Measurement Techniques, Numerical Analyses and Full Scale Testing

Abstract

The production of steel OCTG products with guaranteed external collapse pressure (high collapse casing) requires the implementation of an accurate process control. To develop that process control it is necessary to investigate how different parameters affect the external collapse pressure of pipes. Two dimensional finite element models provide an useful tool for performing the "first approach" parametric studies; however a bidimensional representation of the tube geometry (as used in many analytical and semi-empirical formulas) is not enough for determining the external collapse pressure of casings. We use three dimensional models to further investigate the effects of the casing geometry on its external collapse pressure. To acquire the data that dscribes the geometry of casing samples, we have developed an imperfections measurement system following previous developments by Yeh and Kyriakides. We also present finite element models of OCTG connections which are used as a tool for the evaluation of connections collapse pressure.