Experiment on the Stuck-Point Prediction of Drill String
钻柱卡点预测实验

Stuck-point prediction is the key to deal with stuck accidents. Two types of drill string were designed by using pipe torsional deformation characteristics. One is the single string without drill stem joints, and the other one is the assembly string with drill stem joints. Calculation formulas were established, respectively to predict the depth of stuck-point (DSP). Loading experiments were carried out on the experimental platform of pipe mechanics. Equipment's accessories were used in experiments, such as four-component sensors, wireless data transportation system, HP data sampling system and relevant data processing software. Experimental results are presented as follows: the relative error is -1.88% for single string, is -3.8% for assembly string without taking into account the effect of joints, and is -1.02% for assembly string taking into account the effect of joints. Experimental results show that the torsion method can be used to predict the stuck-point of drill string in vertical wells, the precision of prediction is affected by joints and the upset parts to assembly string, and the prediction precision is higher when Calculation formulas with modified coefficient are used.