Abstract
We investigate experimentally and numerically suppression of drill-string torsional vibration while drilling by using a sliding mode control. The experiments are conducted on the novel experimental drilling rig developed at the University of Aberdeen [1] and using PDC commercial drill-bits and real rock-samples. A mathematical model of the experimental setup which takes into account the dynamics of the drill-string and the driving motor, is proposed. Then a sliding mode control method is employed to suppress stick-slip oscillations. The experimental and numerical results considering a time delay of the actuator are in a close agreement. Stick-slip vibration is eliminated and significant reduction in vibration amplitude has been observed when using the controller.
Highlights
During a downhole drilling process excessive vibrations can occur, which in most cases have a negative impact on the effectiveness of the process and the drilling equipment [2]
Such vibration may lead to an accelerated wear and premature damage of the expensive drilling equipment
Often different dynamic effects such as bit-bounce, stick–slip, forward and backward whirls may appear in the drilling process
Summary
During a downhole drilling process excessive vibrations can occur, which in most cases have a negative impact on the effectiveness of the process and the drilling equipment [2]. Such vibration may lead to an accelerated wear and premature damage of the expensive drilling equipment. Often different dynamic effects such as bit-bounce, stick–slip, forward and backward whirls may appear in the drilling process. In most studies the cutting process is simulated by a friction between two disks [3]. Firstly, a 2-DOF lumped mass model is developed using the torque-on-bit curves, which capture both the frictional and cutting compo-
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