Abstract In this paper, we develop three methods to achieve reliable closed-loop, tool face control for directional drilling operations. This is a necessary step to achieve closed-loop, automated directional guidance. Our algorithms combine existing industry top-drive controllers with new control approaches. The torsional model we use for the drill string has been field validated and takes into account the Coulomb friction between the drill string and the borehole. These distributed friction terms are either assumed known (or measured) or can be estimated using a state-observer. In this work, we improve such a state-observer to obtain an estimation of the tool face orientation in real-time. We then propose different approaches to control the tool face. The first method is based on a feed-forward control law. It uses the flatness of the model and the estimation of the orientation to generate an admissible trajectory which is then tracked. In the second procedure, we require a stable rotation off-bottom before smoothly changing the reference to zero to stop bit rotation. This change of reference induces a change of orientation that can be estimated and finally compensated by repeating the procedure. Finally, the last method uses a series of trapezoidal setpoint inputs – bumps – to calculate the change in downhole tool face per change in surface orientation before arriving at the correct tool face after three iterations. These three algorithms are illustrated in simulations of field scenarios and their effectiveness and limitations, depending on the reliability and availability of downhole orientation data, are discussed.

中文翻译：

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钻头离底的闭环工具面控制

摘要 在本文中，我们开发了三种方法来实现定向钻井作业的可靠闭环工具面控制。这是实现闭环、自动定向引导的必要步骤。我们的算法将现有的工业顶驱控制器与新的控制方法相结合。我们用于钻柱的扭转模型已经过现场验证，并考虑了钻柱和钻孔之间的库仑摩擦。这些分布的摩擦项要么假设为已知（或测量），要么可以使用状态观察器进行估计。在这项工作中，我们改进了这样的状态观察器，以实时获得工具面方向的估计。然后我们提出了不同的方法来控制工具面。第一种方法基于前馈控制律。它使用模型的平坦度和方向的估计来生成可接受的轨迹，然后对其进行跟踪。在第二个过程中，我们需要在平稳地将参考值更改为零以停止位旋转之前稳定旋转离底。这种参考的变化会引起方向的变化，可以通过重复该过程来估计并最终补偿该方向的变化。最后，最后一种方法使用一系列梯形设定点输入（颠簸）来计算井下工具面在三次迭代后到达正确工具面之前每次表面方向变化的变化。这三种算法在现场场景的模拟中进行了说明，并讨论了它们的有效性和局限性，这取决于井下定向数据的可靠性和可用性。