异常高压特高产气井井下管柱力学分析

MECHANICS ANALYSIS OF DOWN-HOLE STRING IN ABNORMAL HIGH PRESSURE AND HIGH-PRODUCTIVITY GAS WELL

对异常高压、特高产气井完井及生产过程中的管柱受力进行分析,是确保气井长期安全生产的重要课题之一。现有的管柱力学计算方法基本是建立在Lubinski模型的基础上,只能分析、计算封隔器坐封好后由于温度、压力的改变而产生的温度效应、活塞效应、鼓胀效应和螺旋弯曲效应,而对于封隔器坐封前后管柱受力的变化、浮力的转移、生产过程中气体的粘滞力则没有现成的计算模型。文章通过将管柱受力分解为管柱入井、假定工况不变且无位移情况下的封隔器坐封以及工况改变且有位移时的封隔器坐封三步,在逐步推理的过程中分析了克拉2气田3口异常高压、特高产气井在完井过程中的管柱受力问题,对封隔器坐封前后浮力的转移、坐封过程管柱受力的变化进行了分析计算。并且采用新方法对生产过程中气体的粘滞力进行计算,最终给出了针对异常高压、特高产气井完井及生产的安全建议。

At present,based on Lubinski model,pipe string mechanics is analyzed after packer setting,but the force changes of pipe string,transfer of buoyancy force,friction force brought by gas flowing in production can't be calculated before and after packer setting.The paper analyzed the pipe string mechanics of three gas wells in Kela 2 Gas field which have characteristics of abnormal high pressure and very high-productivity during completion,and calculated the transfer of buoyancy force and the force changes of pipe string by packer setting in free motion of the tubing,packer setting without changes in operating mode and displacement of tubing,and packer setting with changes in length of tubing.A new method is put forward to analyze and calculate the buoyancy force transfer before and after packer setting,force changes of pipe string,friction force brought by gas flowing in production.As a result,the paper offered the advice which can ensure the safe production of these gas wells.