Numerical Estimation of Hydraulic Forces on a Three-Dimensional Moving Tool-Joint Through a Coupled Fluid-Structure Interaction Model

Drill-string vibration is an important source of issues during drilling operations. Although much research has been done in the last decades, little is known about the interaction between the drill-string vibration and the fluid flow. Most of the models consider only simplified solutions therefore limiting the applicability of the results. Often, those tackle neither the complex rheological behavior of the drilling fluid nor the fluid velocity field itself. In this work, the fluid movement around a moving tool-joint is solved through the Navier-Stokes equation and the forces at the tool-joint is directly estimated from the mesoscopic properties of the fluid flow, without resorting to simplifications, e.g.: drag and lift models. To do so, a tool-joint is assumed to rotate at constant velocity, while moving with a prescribed dynamic, while the flow dynamics is obtained with the lattice-Boltzmann method. Then, the forces and torques at the structure are estimated and evaluated. The simulation results indicate that axial and lateral forces can often be uncoupled, whereas torques are dependent on the dynamics. Finally, they are compared with a reduced order method. It is found that the latter can represent the dynamic accurately for the simplest cases.