欠平衡钻井正气举过程井筒瞬态流动数值模拟  

Transient flow characteristics of gas lift in underbalanced drilling

作　　者：魏纳[1] 孟英峰[1] 李皋[1] 李永杰[1] 徐朝阳[1] 李红涛[1] 

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室,成都610500

出　　处：《石油学报》2014年第1期166-171,共6页Acta Petrolei Sinica

基　　金：国家重大科技专项(2011ZX05021-003);国家重点基础研究发展计划(973)项目(2010CB226700);国家自然科学基金项目(No.51204140;No.51104124;No.51334003;No.L1322021);四川省教育厅科技项目(13ZB0189);油气藏地质及开发工程国家重点实验室(西南石油大学)开放课题(PLN1309)资助

摘　　要：正举法气举作业的实施效果直接决定着欠平衡钻完井施工的成败,特别是气举过程中的井下压力动态演变,关系到整个作业过程中的井控安全。正举法气举作业的实质是在井下停止循环的初始条件下氮气连续气举作业,井下流体由静止状态到气体穿越液体滑脱至井口的不同于常规稳态流动的瞬态气液两相流动。针对这一特殊流动研究,完成了停止循环开井条件下气举时井下瞬态气液两相流动特征参数变化数值模拟计算方法和数学求解模型的建立,通过实际井数值计算连续气举时井下瞬态气液两相流特征参数变化得出规律性认识,如氮气沿井眼滑脱上升运动速度逐步加大、顶出钻井液随时间的增多、井底流压瞬时波动在初始阶段最大等。研究成果丰富了欠平衡氮气钻完井施工正举法气举作业的井筒流动模型体系和压力控制方案,增强了该特殊流动规律的认识,为井控安全提供了理论保障。The implementation of gas-lift operation directly determines the success or failure of the completion of construction in un- derhalanced drilling. In particular, dynamic changes in downhole pressure are related to the security of well control in the entire op- eration process. The essence of gas-lift operation is that under the initial downhole conditions after the stop of well circulation, gas- lift operations are continued by nitrogen; when the gas crosses downhole fluid in a static state, the fluid slips to the borehole and turns to a transient gas-liquid two-phase flow that is different from routine steady flow. A calculation method and a mathematical model are established for numerical simulation of characteristic parameter changes in the downhole transient gas-liquid two-phase flow during continuous gas lift after the stop of well circulation. Characteristic parameter changes in the downhole transient gas-liq- uid tow-phase flow during continuous gas lift are calculated from measured data of actual well, from which the following patterns are summarized： （1） The speed of nitrogen slipping upward along the borehole rises gradually; （2） The volume of drilling fluid ejected grows over time; and （3） The transient fluctuation in bottomhole flow pressure is greatest at the initial phase. The results contribute to the improvement of wellbore flow model system and pressure control program in gas lift operations after completion of construc- tion in underbalanced nitrogen drilling, provides new insights to the characteristics of the special flow, and ensures the security of well control in gas-lift operations.

关 键 词：欠平衡钻井 停止循环 气举 瞬态流动 数值模拟 

分 类 号：TE21[石油与天然气工程—油气井工程]