Casing drilling has been recognized as a practical method to reduce drilling costs and avoid particular drill string problems that often occur in conventional drilling processes. To gain a better understanding of the whirling motion of rotating casing, the energy method was adopted to calculate the critical whirling speeds of casing for both pinned-pinned and fixed-fixed types of support. The calculated critical whirling speed of rotating casing for fixed-fixed supports was found to be 2.35 tunes than that of pinned-pinned supports. To observe the motion patterns of rotating casing in different cases, experiments were conducted in a transparent wellbore. Rotary speed and inclination angle were found to be the two main factors that affect the motion pattern of rotating casing. For the case of 300 gallons per minute (gpm) flow rate with annular fluid of water whirling motion was observed to initiate with a rotation speed of 120 rpm. Steady whirling motion was observed at ~155 rpm and higher With increasing inclination angles, whirling motion was found less likely to occur The backward whirling was not observed in the experiments because the friction between casing and simulated wellbore was not large enough. The variations of torque as a function of rotary speed at different flow rates, inclination angles, and rates of penetration (ROP) were also investigated, and the results were found useful for predicting the quality of borehole cleaning. It was shown that flow rate, inclination angle, and ROP have notable influence on the torque required to rotate casing. With increasing inclination angle, torque was found to increase and reach the maximum value at the horizontal position. For a given ROP, torque was found to decrease with increase in flow rate. For a given flow rate, torque was found to increase with increased ROP.

中文翻译：

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模拟套管钻进旋转运动及扭矩与转速关系的试验研究

套管钻井已被公认为降低钻井成本并避免常规钻井过程中经常出现的特定钻柱问题的实用方法。为了更好地理解旋转套管的涡旋运动，采用能量法计算了销钉和固定式支座的套管临界涡旋速度。经计算，固定支架的旋转套管临界转速比销钉支座高 2.35 曲。为了观察不同情况下旋转套管的运动模式，在透明井筒中进行了实验。发现旋转速度和倾角是影响旋转套管运动模式的两个主要因素。对于每分钟 300 加仑 (gpm) 的流速，观察到环形流体的水旋转运动以 120 rpm 的转速开始。在~155 rpm 和更高时观察到稳定的旋转运动 随着倾斜角的增加，发现旋转运动发生的可能性较小 在实验中没有观察到反向旋转，因为套管和模拟井眼之间的摩擦力不够大。还研究了在不同流速、倾角和穿透率 (ROP) 下作为转速函数的扭矩变化，发现结果可用于预测钻孔清洁质量。结果表明，流速、倾角和 ROP 对旋转套管所需的扭矩有显着影响。随着倾斜角度的增加，发现扭矩增加并在水平位置达到最大值。对于给定的 ROP，发现扭矩随着流速的增加而降低。对于给定的流速，发现扭矩随着 ROP 的增加而增加。