Exploring the nonlinear dynamics of a horizontal drillstring subjected to friction and shocks effects

Abstract

This paper presents a model to describe the nonlinear dynamics of a drillstring in horizontal con guration, which is intended to correctly predict the three-dimensional dynamics of this complex structure. This model uses a beam theory, with e ects of rotatory inertia and shear deformation, which is capable of reproducing the large displacements that the beam undergoes. Also, it considers the e ects of torsional friction and normal shock due to the transversal impacts between the rotating beam and the borehole wall, as well as, the force and the torque induced by the bit-rock interaction. This is done as a rst e ort to solve a robust optimization problem, which seeks to maximize the rate of penetration of the drillstring into the soil, to reduce the drilling process costs. Numerical simulations reported in this work shown that the developed computational model is able to quantitatively well describe the dynamical behavior of a horizontal drillstring, once its reproduces some phenomena observed in real drilling systems, such as bit-bounce, stick-slip, and transverse impacts.