螺杆钻具推力轴承的载荷研究

Load on the thrust bearings of downhole screw motors

离井底循环钻井液时,螺杆钻具传动轴向下的作用力由上轴承承受。一般随着钻压的增加上轴承的载荷有所减小。下轴承不受力。钻井工艺希望的钻头水眼压降对上轴承会造成很大的栽荷,故螺杆钻具都需说明钻头水眼压降的许用的最大值。设计时选用小限流直径、大导程,使用时用大钻压、大水眼、小钻头等措施均能减轻轴承栽荷。工作时万向轴壳体受拉而不受压,因此铰接螺杆钻具所装的铰链能提高钻具的通过性而无确定的造斜能力。

When the drilling fluid circulates at the time that the drill bit is off-bottom, the downward force exerted by the drive shaft of the downhole screw motor is recieved by the upper thrust bearing. As the drilling pressure increases, the load on the upper bearing decreases. The lower thrust bearing is provided for receiving the drilling pressure. For reducing the load on the upper bearing, it is recommended to select small flow control diameter and large lead in design and high drill pressure and small-size bit with large nozzles by application.