使用气动卡瓦钻杆变形原因分析

Analysis of the Deformation Causes of Drill Pipe with Pneumatic Slips

气动卡瓦具有操作简便、大幅提高钻井效率的优势,但在使用过程中存在钻杆变形的问题。文章阐明了气动卡瓦的工作原理,测量了钻杆变形后的尺寸并分析了气动卡瓦夹持钻杆本体的受力情况。根据塑性区内最小压力挤毁公式计算了φ139.7mm钻杆的最小挤毁压力,并与使用过程中φ139.7mm钻杆承受的压强进行对比。基于理论计算的结果,从钻杆动力钳卸扣、DB吊钳卸扣和气动卡瓦推荐取值三个方面分析了钻杆变形的原因。基于钻杆变形的原因,确定了气动卡瓦的安全系数,气动钻杆卡瓦推荐φ139.7mm钻杆的最大起下钻吨位为180t。同时在气动卡瓦使用过程中确保钻杆坐卡的平稳且居中。坚持动力钳卸扣,卸不开扣时及时采用吊卡坐卡后用DB吊钳卸扣。在坐卡吨位较高时及时转换为用吊卡起下钻,确保安全使用钻具。采用上述措施后,川东钻探公司后续井气动卡瓦使用过程再未出现过钻杆夹持部分变形,显著提高了钻井作业的效率。

Pneumatic slip has the advantages of easy operation and improved drilling efficiency.However,there is a problem of deformation of drill pipe when pneumatic slip is used in drilling operations.The working principle of pneumatic slip was clarified in this paper.The size of the drill pipe after deformation was measured.The force of the drill pipe was analyzed when the pneumatic slip clamped the drill pipe.According to the minimum squeeze pressure formula in the plastic zone,the minimum squeeze pressure of 139.7 mm drill pipe was calculated.The pressure generated by the pneumatic slip squeezing the drill pipe was compared with the minimum squeeze pressure.According to the theoretical calculation results,the reasons for the drill pipe deformation were analyzed through three aspects of drill pipe power tong shackles,DB tongs shackles and pneumatic slip recommended values.Based on the reason of the drill pipe deformation,the safety factor of pneumatic slip was determined.The maximum tonnage of the 139.7 mm drill pipe is 180 tons.When pneumatic slips are used to fix the drill pipe,the drill pipe should be kept centered.Power tongs are often used for shackles.When the buckles cannot be detached,the DB tongs are used for shackles.In order to ensure the safety of the drilling tool,the elevator is used to make a trip when the weight of the drilling tool is high.After the above measures were adopted,the pneumatic slips in subsequent wells did not have the deformation of the drill pipe clamping part.Drilling efficiency has been significantly improved.