Dynamic evaluation method of anti-deflection characteristics of double-stabilizer pre-bending BHA

Deviation control and fast drilling of vertical well has always been a difficult problem in the field of drilling. Pre-benting BHA technolog uses pre-bending structure to guide BHA deformation to produce large dynamic deflection reduction force, so as to realize the purpose of dynamic deviation prevention and fast drilling. However, the dynamic quantitative evaluation of deviation prevention characteristics of pre-bent BHA is still a difficult problem. Based on the dynamic model established by Jansen, the dynamic lateral force model at the bit is established. The eddy trajectory data of section A obtained from simulation is applied to the calculation of dynamic lateral force. Finally, the anti-deviation characteristics of this kind of drilling tools are evaluated quickly and intuitively through whirl trajectory diagram, dynamic lateral force distribution time history diagram and average dynamic lateral force. The simulation results show that: （1）With the increase of well deviation angle, the force of reducing inclination increases; （2）With the increase of rotating speed, the anti-deviation characteristics of drilling tools can be divided into three stages: stable, unstable and losing the ability of reducing deviation;（3） Under different inclination angles, the first and second critical speeds increase with the increase of well deviation angle. Through the study of the above models and laws, the mechanism of deviation prevention and declination of the pre bent BHA with double stabilizers is further revealed, which is of great significance to the application of pre bent BHA in the field.