A Finite Element Analysis of Collapse of Perforated Casing

Abstract

The purpose of this paper is to report the results of finite element analyses of the collapse of perforated casing. In the study, both inline (0-deg phasing) and staggered (90-deg phasing) patterns are considered. The primary intent of the study is to illustrate the severe loss of casing cross-sectional integrity accompanying extrusion of a ductile formation into the wellbore. It is shown that, for reasonable perforation densities, the primary effect of the perforation pattern is not strength reduction of the cross section, but definition of a nonuniform loading pattern resulting from formation production. In this regard, in the presence of large-scale formation failure in the near wellbore region, it is crucial to the integrity of the casing that a solids control technique be employed.