一根3600米长的钻柱被用于打捞落在井中的钻杆,在打捞作业中,其上部发生断裂。在这类情况下使用的钻柱都要承受很高的静载拉应力、扭应力和弯曲应力,往往达到或超过钢材的屈服极限,因此常常会发生断裂。在这种情况下,断留在井中的钻柱或钻杆接头,尤其 A 3,600-meter long drill string was used to retrieve the drill pipe that fell in the well, where the upper part fractured. Drills, which are used in such cases, are subject to high static tensile, torsional and flexural stresses, often exceeding or exceeding the yield limit of the steel, so that fractures often occur. In this case, the drill string or drill pipe joint that is left in the well is, in particular