溢流过程井筒气液两相流流动规律研究  

Study on the Flow Law of Gas-liquid Two-phase in Wellbore during Overflow Numerical Simulation of Formation Leakage Induced Overflow

作　　者：梁爽 王鹏程[2] 杨云朋 袁立凡 李勇 Liang Shuang;Wang Pengcheng;Yang Yunpeng;Yuan Lifan;Li Yong(CNPC Research Institute of Safety&Environment Technology;CNPC Tarimu Oilfield Company)

机构地区：[1]中国石油集团安全环保技术研究院有限公司 [2]中国石油塔里木油田公司

出　　处：《油气田环境保护》2025年第1期28-32,共5页Environmental Protection of Oil & Gas Fields

摘　　要：钻井过程中地层漏失与井下溢流的发生会增大井控风险,一旦控制失效会导致井喷的发生。文章基于气体状态方程、井筒气液两相流模型,通过对地层漏失诱发的井下溢流进行数值模拟,建立由漏失所致的井筒气液两相流瞬态流动模型,并借助某井现场数据,分析溢流过程井筒中含气率、压力和气液两相流量随井深与时间的分布规律,发现初始液面高度越低,井底侵入气体的膨胀现象越明显。由钻柱落井作为启动条件,由此造成地层漏失进而诱发的溢流过程中含气率沿井深的变化呈三段式分布:井筒底部存在高含气段,流体组成以气相为主;沿着井筒向上,静液柱压力降低,气体膨胀,在高含气段气体膨胀较为明显;井筒中部为混合段,中部混合段的含气率随井深减小快速下降;继续沿着井筒向上含气率降为0,在该位置上部是纯液段。漏失引发的溢流过程中,井底压力随时间的增加呈现先增大后减小的变化特征。溢流早期阶段井底欠压,地层中气体高速侵入,致使井底压差增加;溢流中期,井底近平衡时,地层气体慢速侵入,井底压差缓慢增加;溢流后期,井口见返后,由于钻井液返出使静液柱压力减小,且井底压力减小速率逐渐增大,井口见返后的井底压差开始减小。The occurrence of formation loss and downhole overflow in the process of drilling will increase the risk of well control.Once the failure of control will lead to blowout accidents.In this paper,the downhole overflow induced by formation loss was numerically simulated.Combined with gas state equation and wellbore gas liquid two phase flow model,the transient flow model of gas liquid two phase flow in wellbore caused by leakage was established.And by the field data of a well,the distribution law between gas content,pressure and gas-liquid two-phase flow with well depth and time was analyzed.It was found that the lower the initial liquid level height was,the more obvious the expansion phenomenon of the intrusive gas at the bottom of wellbore was.In the overflow process induced by formation loss,a three-stage distribution was presented between the variation of gas content with well depth,resulting from the drill string drop as the starting condition.There was a high gas content section at the bottom of wellbore,and the fluid composition was dominated by gas phase;Upward along the wellbore,the hydrostatic column pressure decreased and the gas expanded,which was more obvious in the high gas content section.The middle part of wellbore was the mixed section,and the gas content of the mixed section decreased rapidly with the decrease of well depth.The gas content dropped to zero upward the wellbore,with pure liquid phase above this position.In the process of overflow caused by leakage,the bottom hole pressure increased first and then decreased with the increase of time.In the early stage of overflow,there was under pressure at the bottom of well,and gas entered the formation at a high speed,resulting in the increase of the pressure difference at the bottom of the well;In the middle stage of overflow,when the wellbore was nearly in equilibrium,the gas slowly invaded into the formation and the pressure difference at the bottom of the well slowly increased;In the later stage of overflow,the hydrostatic column pressure decrea

关 键 词：钻井 溢流 含气率 压力 

分 类 号：TE28[石油与天然气工程—油气井工程]