Study on Dynamic Vibration Characteristics of Drill String in Extended Reach Well

Drill string vibration is one of the main causes of drill string damage during drilling. It is very important to study the vibration characteristics of drill string and the influence of parameters such as WOB and rotary speed to reduce the fatigue failure of drill string. In order to grasp the dynamic safety of the drill string, a finite element model of full-well drill string is set up, which is suitable for actual drilling track and drill string combination. The model takes into account various factors such as non-linear contact between drill string and wellbore, viscous damping of drilling mud to drill string movement, and drill-rock interaction, which makes simulation analysis closer to practical conditions. The HHT method and the node iteration method were applied for analyzing the axial and lateral acceleration of the drill string to understand the vibration safety of the drill string. The results show that the lateral acceleration of drill string is greater than the longitudinal acceleration, and the lateral vibration is stronger at the bottom of wellbore. With the increase of drilling fluid density、WOB and the rotation speed, the vibration of drill string more and more intense.