摘要
在陆上井下双梯度控压钻井过程中气侵是面临的主要挑战之一。研究气侵过程中,井筒气-液两相流动规律对气侵检测与处理具有重要意义。因此,文中基于钻井液、气体和空心球的质量、动量和能量守恒方程,考虑变梯度参数引起的环空变质量流动和井筒多相流行为,建立了井下双梯度控压钻井气侵条件下的全瞬态气-液两相流新模型,并利用该模型分析了井下双梯度控压钻井气侵过程中井筒内的气-液两相流动规律。模拟结果表明:变梯度参数不仅会改变气相体积分数和当量循环密度(ECD),而且能够影响气侵演变规律;井下双梯度控压钻井环空ECD整体上近似呈“折线形”分布,能够更好地适应深层超深层的窄安全密度窗口;将空心球比例、旋流分离器位置和分离效率相结合,能够灵活地调整环空ECD分布。该研究对使用井下双梯度控压钻井解决陆上窄安全密度窗口地层的钻井难题具有重要的理论和工程意义。
Gas invasion is one of the main challenges in the process of downhole dual-gradient controlled pressure drilling on land.The study of the gas-liquid two-phase flow law in the wellbore during gas invasion has a vital importance for gas invasion detection and treatment.In this paper,based on the energy conservation equations,momentum and quality of drilling fluid,gas and hollow sphere,the new model of total transient gas-liquid two-phase flow under gas invasion conditions of downhole dual-gradient controlled pressure drilling is established by considering the variable mass flow in annulus caused by variable gradient parameters and the multi-phase flow behavior in wellbore.With this model,the gas-liquid two-phase flow law in the wellbore during gas invasion of downhole dual-gradient controlled pressure drilling was analyzed.The simulation results show that:the variable gradient parameters will not only change the volume fraction and equivalent circulation density(ECD)of the gas phrase,but also affect the evolution of gas invasion.The annular ECD distribution in downhole dual-gradient controlled pressure drilling is approximately"broken line",which can better adapt to the narrow safety density window in deep and ultra-deep layers.The distribution of annular ECD can be flexibly adjusted by combining the concentration of hollow spheres,the position of cyclone separator and the separation efficiency.The research has significant theoretical and engineering significance for solving the drilling problem of narrow safe density window formation on land by using downhole dual-gradient controlled pressure drilling.
作者
蒋振新
李军
郭勇
吴德胜
时培忠
杨宏伟
张更
JIANG Zhenxin;LI Jun;GUO Yong;WU Desheng;SHI Peizhong;YANG Hongwei;ZHANG Geng(Oil Production Technology Research Institute,Xinjiang Oilfield Company,PetroChina,Karamay 834000,China;China University of Petroleum(Beijing)at Karamay,Karamay 834000,China;College of Petroleum Engineering,China University of Petroleum(Beijing),Beijing 102249,China)
出处
《断块油气田》
CAS
CSCD
北大核心
2024年第5期936-944,共9页
Fault-Block Oil & Gas Field
基金
中石油集团公司重大专项“砾岩油藏规模上产与提高采收率关键技术研究”(2023ZZ24-05)。
关键词
双梯度控压钻井
气侵
井筒多相流
当量循环密度
dual-gradient controlled pressure drilling
gas invasion
multiphase flow in wellbore
equivalent circulating density
