Dynamic Analysis of Drill String and Wellbore in Ultra Short Radius Wells Based on Abaqus

Abstract

Economic and efficient ultra-short radius horizontal drilling technology is an effective technology to increase the production of old oilfields. However, the fatigue breakage of the drilling string and wellbore and the coupling vibration between the drilling string and wellbore are the critical problems encountered in its engineering applications. We took the drilling string and wellbore of an experimental simulation of ultra-short radius as the object of research, set up the mechanical and mathematical model with strong adaptability, and applied theories to analyze the force condition of the drilling string and ultra-short radius wellbore. Consequently, a 3D computational model representing the drilling string and wellbore was built. The dynamic simulation software Abaqus was utilized to simulate the working force state of the ultra-short radius wellbore and drilling string, analyze the force generated by mutual contact movement under various operating conditions, and investigate the drilling string's dynamics and stability during the tripping process. The results reveal that the drill string's rotating speed influences its tripping ability: more intense the speed, greater the decrease in axial force. Thus, the rotational speed can be changed, and the lubrication between the wellbore and drill string can be improved to reduce the force between the drill string and wellbore, which is conducive to the entry of the drill string.