Contact nonlinear finite element analysis of controllable universal joint flexible slender in tube

Key words:  flexible slender  beam element  universal joint  nonlinear  finite element method

Abstract:

The flexible slender with controllable universal joints in a tube (of wellbore during well drilling) can be considered as a beam-to-beam contact of nonlinear problem with the mutual transformation between the mechanism and the structure. In this study, based on the structural characteristics of the controllable universal joint, an universal joint element was constructed and its motion constraints were given, combined with 3-D beam element and contact element. A contact nonlinear finite element model between the controllable universal joint flexible rod and the outer tube was established. A modified Newton Simpson method was applied for the numerical solution of the model, and the simulation results were compared with an analytical solution in a case study, and the calculation results are in good agreement. Taking a flexible drilling tool assembly in a deflecting section of horizontal well drilling with an ultra-short radius as an example, the influence of different rotation limits of the universal joints on deformation and load transfer of the flexible drill pipe was studied. The results show that the universal joint flexible drill rod has a "line shape" deformation under the action of its own weight and torque. With the increase of rotation limit at the hinged joint, the relative rotation angle of the flexible drill rod and the contact pressure with the guide pipe gradually increase, while the torque gradually decreases.