考虑摩阻的圆弧井卡点深度计算模型研究

摘要

管柱卡点深度计算对整个大修工艺具有重要意义.现有的卡点计算模型忽略了井斜和动摩擦因数对卡点深度计算的影响,造成卡点深度计算与实际情况出现较大误差.鉴于此,基于胡克定律和微积分原理,在考虑圆弧井井斜及动摩擦的影响下,建立了单一与复合管柱卡点深度计算模型,并给出了相应的数学解.对比分析结果表明:该模型能够更好地描述卡点深度与管柱伸长量之间的关系,使得卡点深度计算更为精确;现场作业中若忽略这种计算差异,会导致管柱在受拉时达到抗拉强度极限而损坏管柱,且在需要使用倒扣工艺解卡时会影响倒扣精度,造成不必要的井下二次事故.研究结果对大修倒扣工艺的现场应用具有一定的指导意义.%The calculation of the free point depth of tubular is of great significance to the entire workover process.The previous calculation model does not take the well inclination and dynamic friction factor into consideration,resulting in a large error.Based on the Hooke's law and the principle of calculus,considering the well inclination and the dynamic friction of the circular arc well,the free point depth calculation model of the single-pipe string and the composite pipe string was established.Corresponding mathematical solutions were then given.Comparative analysis showed that the model could better describe the relationship between the free point depth and the elongation of pipe string,and make the calculation more accurate.If this calculation difference is neglected in the field work,pipe string may be pulled to the ultimate tensile strength to cause failure,and back-off accuracy would be affected in pipe free operation,resulting in unnecessary subsequent downhole accidents.The study results could provide guidance to the on-site application of workover back-off process.