Two-side estimates of rigidity and strength of casing centralizer

Abstract

The problem of the interaction of elastic rod casing centralizers with the wellbore wall is considered. The paper aims at studying the influence of the axial mobility of the centralizer’s ends on the parameters of its rigidity and strength. These characteristics are necessary to assess the possibility of the casing string and quality of well completions. Classical linear theory of shallow rods is used to model operating link of the centralizer. Physically the rod is taken for inextensible along the axis and elastic for bending. The stress-strained state of the arcuate rod with various fastening options in the conditions of point contact is studied. Analytical dependences between the contact force and the mutual convergence of the casing string and the borehole wall, as well as formula for the equivalent stress are determined. A way of fastening the rod along the axis of the pipe significantly affects these characteristics, in particular, presence or absence of reciprocal displacements of the ends of the rod in the axial direction. The engineering formulas of two-side estimations of rigidity and strength of real centralizers’ designs are obtained.