气举柱塞偏心环空间隙流场数值分析  

Numerical Analysis of Flow Field in Eccentric Annular Clearance of Gas-lift Plunger

作　　者：田柯 高尔斯 王汉 崔璐[1] 窦益华[1] TIAN Ke;GAO Er-si;WANG Han;CUI Lu;DOU Yi-hua(College of Mechanical Engineering, Xi'an Shiyou University, Xi'an 710065, China;Linfen Branch of PetroChina Coalbed Methane Company Limited, Linfen 042300, China;Engineering Technology Research Institute, Petro China Southwest Oil and Gas Field Company, Chengdu 610031, China)

机构地区：[1]西安石油大学机械工程学院,西安710065 [2]中国石油煤层气有限责任公司临汾分公司,临汾042300 [3]中国石油西南油气田分公司工程技术研究院,成都610031

出　　处：《科学技术与工程》2021年第36期15446-15453,共8页Science Technology and Engineering

基　　金：陕西省教育厅专项科研计划项目(20JK0836);西安石油大学研究生创新与实践能力培养计划(YCS20213181)。

摘　　要：柱塞气举利用井底压差推动柱塞沿井筒运动,依靠柱塞与管壁间隙密封举升上部液体至井口,达到排水采气目的。目前,针对柱塞实际运动中发生偏心对气举密封的影响认识不够清晰,导致无法进一步优化柱塞密封结构和工艺参数。为此,利用气液两相分层流动数值计算方法,讨论了紊流槽内相含率和速度场变化规律,并分析其多道密封机理,获得不同偏心距导致的环空间隙差异条件下柱塞密封效果。结果表明:当柱塞与油管轴线处于同心状态作业时,根据特定场合设计的柱塞外壁紊流槽的密封效果可以满足气举要求,但由于柱塞运动时很难保证同心,随偏心距逐渐增大,柱塞与油管间隙增大导致其密封效果逐渐变差。在偏心距为0.9 mm时,窜气量相比同心状态增加140.33%,大量气体发生滑脱;偏心距为1.5 mm时,液体以0.29 kg/s的速度泄露至柱塞下方区域。故偏心状态对气举柱塞密封性能的影响不容忽视,对此修正柱塞偏心环空状态下的运动方程,以探究柱塞偏心后对启动压力和单次循环排液量的影响。The gas-lift plunger is driven by the pressure difference of bottom hole to move along the wellbore,and the upper liquid is lifted to the wellhead by sealing between the plunger and the pipe wall,which can achieve the purpose of drainage and gas recovery.At present,the influence of the eccentricity on seal is not clearly recognized in the actual movement of the plunger,resulting in the plunger sealing structure and process parameters that cannot be further optimized.Using the numerical calculation method of gas-liquid two-phase stratified flow,the variation law of the phase holdup and velocity field in the turbulent flow groove was discussed,the multi-channel sealing mechanism was analyzed,and the plunger sealing effect in the difference annulus gap caused by different eccentricity was obtained.The results show that the sealing effect of the turbulence groove on the outer wall of the plunger can meet the requirements of gas lift when the plunger axis coincides with the tubing axis.However,it is difficult for the plunger to ensure concentric motion.So with the increase of eccentricity,the increased clearance between plunger and tubing wall will lead to the gradual deterioration of the sealing effect of turbulent groove.When the eccentricity is 0.9 mm,the gas channeling volume increases by 140.33%compared with the concentric state,and a large amount of gas slippage occurs.When the eccentricity is 1.5 mm,the liquid leaks into the lower region at a rate of 0.29 kg/s.Therefore,the influence of eccentric state on the sealing performance of gas lift plunger cannot be ignored.The motion equation of eccentric plunger in annulus is modified to investigate the influence of eccentric plunger on starting pressure and single cycle drainage volume.

关 键 词：气举柱塞 密封机理 偏心环空 气液两相流 数值模拟 

分 类 号：TE377[石油与天然气工程—油气田开发工程]