Determination of Pipe Pullback Loads in Horizontal Directional Drilling Using an Advanced Computational Dynamic Model

Abstract

While several procedures or guidelines for predicting pullback loads in pipe installation using the horizontal directional drilling (HDD) technique have been developed, they are based on static assumptions and are approximate analytical or empirical methods. Because of the nature of HDD, determination of the pipe pullback loads is a complex dynamic problem. This paper presents a new dynamic model to simulate the pipe pullback process and numerically calculate the pipe pullback loads in HDD installation, where the pipes are modeled by three-dimensional Euler-Bernoulli flexible beam elements based on an absolute nodal coordinate formulation and the interaction between the pipes and the borehole/ground surface is described by a local contact model using the nonlinear Hertz contact theory. To evaluate the method presented, a typical case of HDD installation is examined. The analytical solution of the case in the steady state is derived to validate the method presented. Numerical results for such useful details as the pulling force, the transient and steady-state axial forces at different locations of the pipes, and the axial stresses in the pipes during and after installation are provided.