Dynamic analysis of bottom hole assembly with external vibrating force excitation

Abstract

As a Vibration Assisted Rotary Drilling (VARD) tool, the newly developed Down-hole Oscillating Device (DOD) is designed for the purpose of improving drilling efficiency. The performance of the DOD was studied theoretically in this thesis. Computational Fluid Dynamics (CFD) simulation is conducted to thoroughly investigate the axial vibration force generated by the DOD. Parametric analysis is then conducted to study whether different drilling fluids can vary the DOD output. Afterwards, dynamic Bottom Hole Assembly (BHA) models are built to evaluate how this additional vibration force affects drilling. In this thesis, both a single rigid body model and finite element model of the BHA are established. Some other simulations are conducted with the finite element model to investigate how various external vibration forces influence drilling enhancement.