高速注采储气库井套管螺纹密封性研究

A Study on Sealing Performance of UGS Well Casing Thread Under High-speed Injection-production

套管螺纹密封性是影响周期性高速注采作业的储库气井安全性的关键因素,因此保证储气库井的密封性完整极其重要。需要重点研究储气库井注采过程中对其套管柱密封性的影响,特别是循环注采过程中产生的交变载荷对储气库套管柱特殊螺纹接头密封结构性能的影响。基于有限元法理论,针对中国北部某储气库井所选用的特殊螺纹接头,结合储气库井实际工况和现场数据,建立套管接头螺纹有限元计算模型,研究了循环注采条件下,温度、注采压力、轴向载荷及点蚀对储气库套管螺纹密封状态的影响。结果表明,温度对套管螺纹接头的结构完整性和密封完整性影响较小,注采压力、轴向载荷和点蚀对其影响较大,需控制在一个较低值。研究可为储气库井套管柱密封失效判定及其套管柱设计提供参考。

The sealing of casing thread is a key factor affecting the safety of UGS(Under Gas Storage)well for periodic highspeed injection and production operation,so the integrity of sealing of gas storage well is extremely important.It is necessary to focus on the influence of gas storage well injection and production process on the sealing property of the string,especially the variation law of the special thread joint sealing structure performance of the UGS string caused by the alternating load in the process of circulating injection and production.Based on the theory of finite element method,combined with the actual working condition of the UGS well and field data of a special thread joint used in a UGS well in northern China,a special thread joint finite element calculation model is established and the cycle injection-production condition,temperature,injection-production pressure,axial load and pitting of the effects of the casing thread seal UGS is studied.The results show that the temperature has little effect on the structural integrity and sealing integrity of the casing thread joint,but the injection-production pressure,axial load,and pitting have a great effect on it,which should be controlled at a low value.This study can provide a reference for sealing failure determination and pipe string design of gas storage wells.