扭转振动工具滑模控制降黏分析

在深部硬地层钻井领域,扭转振动工具具有破岩效果明显和抑制钻头黏滑的作用,但其相应的降黏机理和控制机理研究还不完善。为此,在现有通过扭转振动工具解决黏滑问题的基础之上,建立了钻柱系统的扭转振动方程,提出U1和U2两种滑模控制降黏方法,并在有工具作用时,结合理论方程、给定参数对两种控制方式的降黏效果进行了分析。结果表明:当存在参数摄动时,钻柱系统处于黏滑状态附近,参数的变化会导致钻柱系统的脆弱性,钻柱系统需要加以控制;两种滑模控制方式均能有效对钻柱的黏滑振动进行控制;通过对在不同条件下各控制器的控制性能、鲁棒性的对比可知,滑模控制方式U2整体控制性能较好,且滑模控制方式U2具有更强的鲁棒性,有利于提高钻柱系统的稳定性和可靠性。

Viscosity reduction analysis of the sliding mode control of a drill string system with a torsional vibration tool

In the deep hard formation drilling field, the application of a torsional vibration tool has the effect of rock breaking and stick slip inhibiting, however, the study on the corresponding viscosity reduction mechanism and control mechanism has not yet been well provided.On the basis of a drill string system model with the torsional vibration tool, the effect of viscosity reduction of the stick-slip control method was studied.Two sliding mode control methods, U 1 and U 2, were designed.Making use of the control equations and giving proper parameters, the viscosity reduction effect and the stability of the two control modes were analyzed.The results show that both sliding mode control methods can effectively control the stick-slip vibration of the drill string.By comparing the control performance and robustness of the two controllers under different conditions, it is found the sliding mode control U 2 has better overall control performance and stronger robustness, which is beneficial to improve the stability and reliability of the drill string system.