Helical buckling of pipe with connectors in vertical wells

The effect of connectors on pipe buckling is acknowledged, but has received Little attention. Lubinski analyzed the effect of connectors on pipe in te nsion in a curved borehole, while Paslay and Cernocky extended this analysi s to pipe in compression. These papers indicate that bending stresses are g reater due to connector standoff. However, these papers do not consider a b uckled pipe. This paper presents an analytic solution of the beam-column equations in th ree dimensions for a helically buckled pipe with connectors in a vertical w ell. For low axial compression, the solution approximates helically buckled pipe without connectors, however, at higher axial forces, the effects of c onnectors on contact forces and bending stress becomes significant. Sag bet ween connectors is calculated so that pipe body contact between connectors can be determined. Applications include the analysis of bottomhole assemblies, drillpipe, casi ng, and tubing. The solutions are simple formulas that are suitable for han d calculations.