Hydrocarbon exploration and production activities are guaranteed through various operations including the drilling process, which is realized by using rotary drilling systems. The process involves crushing the rock by rotating the drill bit along a drill string to create a borehole. However, during this operation, violent vibrations can occur at the level of the drill string due to its random interaction with the rocks. According to their axes of occurrence, there are three types of vibrations: axial, lateral, and torsional, where the relentless status of the torsional vibrations is terminologically known as the stick-slip phenomenon. Such a phenomenon can lead to increased fatigue of the drill string and cause its abortive fracture, in addition to reducing the efficiency of the drilling process and consequently making the exploration and production operations relatively expensive. Thus, the main objective of this paper is to eliminate the severe stick-slip vibrations that appear along the drill string of the rotary drilling system according to the LQG observer-based controller approach. The rock–bit interaction term is highly nonlinear, and the bit rotational velocity is unmeasurable; an observer was first designed to estimate the unknown inputs of the model, and then the controller was implemented in the drill string model with 10 degrees of freedom. The estimation process was essentially based on surface measurements, namely, the current and rotational velocity of the top drive. Thereafter, the performance of the proposed observer-based LQG controller was tested for different simulation scenarios in a SimScape/Matlab environment, for which the controller demonstrated good robustness in suppressing the severe stick-slip vibrations. Furthermore, the simulation and experimental results were compared to other controllers designed for the same model; the proposed observer-based LQG controller showed better performance, and it was less sensitive to structured disturbances than H∞. Thence, it is highly recommended to use the proposed approach in smart rotary drilling systems.

中文翻译：

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使用基于观测器的 LQG 控制器抑制钻柱粘滑振动

油气勘探和生产活动通过各种作业得到保证，包括使用旋转钻井系统实现的钻井过程。该过程包括通过沿钻柱旋转钻头以形成钻孔来破碎岩石。然而，在此操作过程中，由于钻柱与岩石的随机相互作用，可能会在钻柱的水平上发生剧烈振动。根据它们的发生轴，存在三种类型的振动：轴向、横向和扭转，其中扭转振动的无情状态在术语上称为粘滑现象。这种现象会导致钻柱的疲劳增加并导致其失效断裂，除了降低钻井过程的效率并因此使勘探和生产操作相对昂贵之外。因此，本文的主要目的是根据基于 LQG 观测器的控制器方法消除旋转钻井系统钻柱沿线出现的严重粘滑振动。岩石-钻头相互作用项是高度非线性的，钻头转速无法测量；首先设计了一个观测器来估计模型的未知输入，然后控制器在具有10个自由度的钻柱模型中实现。估计过程基本上基于表面测量，即顶驱的电流和旋转速度。此后，在 SimScape/Matlab 环境中针对不同的仿真场景测试了所提出的基于观察器的 LQG 控制器的性能，该控制器在抑制严重的粘滑振动方面表现出良好的鲁棒性。此外，将仿真和实验结果与为同一模型设计的其他控制器进行了比较；所提出的基于观测器的 LQG 控制器表现出更好的性能，并且它对结构化扰动的敏感性低于 H∞。因此，强烈建议在智能旋转钻井系统中使用所提出的方法。将仿真和实验结果与为同一模型设计的其他控制器进行了比较；所提出的基于观测器的 LQG 控制器表现出更好的性能，并且它对结构化扰动的敏感性低于 H∞。因此，强烈建议在智能旋转钻井系统中使用所提出的方法。将仿真和实验结果与为同一模型设计的其他控制器进行了比较；所提出的基于观测器的 LQG 控制器表现出更好的性能，并且它对结构化扰动的敏感性低于 H∞。因此，强烈建议在智能旋转钻井系统中使用所提出的方法。