This paper describes new theoretical results for prediction of buckling behavior of tubulars in inclined wellbores. Using conservation of energy and the principle of virtual work improved equations for buckling and post-buckling conditions are derived. The effect of torque on the buckling process is considered. Practical examples are provided showing the influence of torque on the critical buckling force. The equations for critical buckling force reduce to those previously derived when torque is set to zero and weightless strings are considered.

Keywords:
lbf, substitution, relation, displacement, equilibrium, drillstring design, axial, inclination angle, directional drilling, society of petroleum engineers
Subjects:
Wellbore Design, Drillstring Design, Drilling Operations, Wellbore integrity, Drill pipe selection, Directional drilling
Copyright 1995, Society of Petroleum Engineers
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