Research and development of drill string mechanics

Drill string mechanics is the basis of the design and control of borehole trajectory, the drill string design, and the drilling parameter optimization. The development of drill string mechanics is discussed from the perspectives of the introduction of the topic, the research objective, the methods employed for the research, the motion behavior of the drill string, the fundamental equation for of drill string dynamics, the tension and torque of the drill string, the elastic stability of the drill string, the stress analysis of the bottom hole assembly, the drill string vibration and swirling. A relatively integrated theory has been developed for the drill string mechanics. The drill string statics developes rapidly with high accuracy. However, the drill string dynamics lags behind considerably, and a lot of problems have not yet been solved. Combined with the development of modern drilling technologies, a preliminary discussion is made on the prospect for the research trend of drill string mechanics. Fundamental theory research, system control theories and methods, dynamic characteristics tests, and fictitious simulation technologies will play an important role in the development of drill string mechanics.