Prediction of Contact Force for Drill Pipe/Coiled Tubing

This paper systematically presents an approach for predicting the contact force for drill pipe/coiled tubing in vertical, deviated, and curved wells corresponding to different pipe configurations, i.e., no-buckled, sinusoidal, and helical configurations. Utilizing the Lagrange multiplier method, the equilibrium equations are obtained for pipe in vertical, deviated, and curved wells. The Lagrange multiplier represents the unit lateral contact force between the pipe and the wellbore. Solving the equilibrium equations simultaneously, the contact forces corresponding to straight, sinusoidal, and helical configurations are derived for drill pipe/coiled tubing in vertical, deviated, and curved wells, respectively.