Dynamics and anti-friction characteristics study of horizontal drill string based on new anti-friction tool

ABSTRACT

In the drilling process of a horizontal well, the large drilling friction between the drill string and the wellbore wall can cause the phenomenon of backing pressure and reduce drilling efficiency. To reduce the drilling friction, a new anti-friction tool is proposed and then dynamics and anti-friction characteristics of the horizontal drill string are studied. According to the actual working conditions, the force analysis of the drill-string system is conducted. The dynamics model of the drill string is established and the vibration anti-friction characteristics of the drill string are studied. The numerical solution method is used to solve the dynamics model and the experimental test is conducted to verify the structural design of the new anti-friction tool. According to the theoretical calculation results, the variation law of the average friction, the vibration characteristics, and the bit rotation velocity response under different initial conditions are obtained, and the experimental test result shows that a new anti-friction tool can generate axial vibration. Through the theoretical and experimental study, the design and development of new downhole anti-friction tools can be improved, which is beneficial to solve the problem of large drilling friction in horizontal wells and can provide technical support for high-efficiency oil and gas well drilling.

KEYWORDS:

• Dynamics
• anti-friction
• horizontal well
• vibration
• drilling friction
• drill string

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [No.11102173]; the State Foundation for Studying Abroad [No.201608515039]; High-end foreign experts introduction plan [SYZ201985]; Double First-rate Foundation of Southwest Petroleum University [2019cxyb001]; Major National Science and Technology Project [No.2016ZX05038].