Hao Zhitong,Liu Fengxia,Liu Zhiliang,et al.Dynamic evolution characteristics analysis and model validation of gas-liquid two-phase flow in coiled tubing[J].China Petroleum Machinery,2026,54(10):126-133.
The dynamic behaviors of gas-liquid two-phase flow in coiled tubing directly affect gas well production performance. However, existing studies are mostly limited to static flow-pattern descriptions under single operating conditions, failing to capture the internal unsteady fluctuation characteristics or reveal the continuous evolution process and transition mechanisms between different flow patterns. In this study, the gas-liquid two-phase flow in coiled tubing was simulated using Fluent software. The dynamic evolution characteristics of flow patterns were analyzed through time-domain liquid holdup signals, probability density function (PDF) curves, and cross-sectional contours, and the accuracies of commonly used engineering models in flow-pattern identification and liquid holdup calculation were compared. The results indicate that slug flow exhibits sawtooth-shaped holdup fluctuations and bimodal PDF distributions, reflecting the periodic alternation of Taylor bubbles and liquid slugs. Churn flow shows stronger randomness of liquid holdup signals, with the PDF curve transitioning to a unimodal distribution and declining to zero at a holdup of 1.0, indicating the disappearance of stable liquid slugs. Annular flow demonstrates reduced fluctuation amplitude of liquid holdup, with the PDF curve presenting a sharp and narrow unimodal, right tailing pattern, corresponding to the formation of a continuous gas core and an uneven liquid film on the pipe wall, along with droplet entrainment–deposition cycles induced by disturbance waves. Model comparison results show that the Govier-Aziz-Fogarasi model exhibits the best overall performance, with accurate identification of pseudo-slug flow and the holdup calculation errors generally below 20%. The Beggs-Brill model accurately identifies intermittent flow at low gas rates but exhibits errors exceeding 20% under some conditions. The Mukherjee-Brill model tends to misclassify churn flow as annular flow at low gas rates, with overall overestimated holdup calculations. These findings provide a theoretical basis for on-site flow-pattern recognition, liquid holdup estimation, and gas-lift injection rate optimization.
Liao Kaigui , Li Yingchuan , Yang Zhi , et al . Study on pressure drop models of gas-liquid two-phase pipe flow in gas reservoir [J]. Acta Petrolei Sinica , 2009 , 30 ( 4 ): 607 - 612 .
Li Zhonghao , Zhang Xingkai , Liao Ruiquan , et al . Research on liquid holdup measurement by conductivity method based on forced annular flow [J]. China Petroleum Machinery , 2022 , 50 ( 4 ): 101 - 110 .
Chen Wen , Luo Wei , Wang Wei , et al . New liquid holdup model of gas-liquid two-phase inclined pipe flow at medium and high flow rates considering pipe diameter [J]. Science Technology and Engineering , 2024 , 24 ( 31 ): 13359 - 13367 .
Liu Hong , Qin Wei , Hu Changquan , et al . Prediction of gas-liquid two-phase flow pattern in Huang 202H shale gas wellbore [J]. Journal of Chongqing University of Science and Technology (Natural Sciences Edition) , 2021 , 23 ( 5 ): 20 - 25 .
Xing Xuesong , Chen Huan , Yu Jifei , et al . Gas-liquid two-phase flow in large liquid horizontal gas well with different gas lift modes [J]. Science Technology and Engineering , 2022 , 22 ( 28 ): 12362 - 12369 .
Qin Feng , Tang Shenglai , Yan Zhenghe , et al . Simulation experiment of liquid carrying in whole wellbore of horizontal gas well [J]. China Petroleum Machinery , 2022 , 50 ( 2 ): 95 - 101 .
Adaze E , Al-Sarkhi A , Badr H M , et al . Current status of CFD modeling of liquid loading phenomena in gas wells: a literature review [J]. Journal of Petroleum Exploration and Production Technology , 2019 , 9 ( 2 ): 1397 - 1411 .
Kiran R , Ahmed R , Salehi S . Experiments and CFD modelling for two phase flow in a vertical annulus [J]. Chemical Engineering Research and Design , 2020 , 153 : 201 - 211 .
Li Yicheng , Hosseini M , Arasteh H , et al . Transition simulation of two-phase intermittent slug flow characteristics in oil and gas pipelines [J]. International Communications in Heat and Mass Transfer , 2020 , 113 : 104534 .
Lin Jianxin , Yu Huiyong , Lu Wenting , et al . Influence of liquid viscosity on slug flow characteristics of vertical upword pipe [J]. Science Technology and Engineering , 2021 , 21 ( 2 ): 551 - 557 .
Jing Jiaqiang , Yin Xiaoyun , Mastobaev B N , et al . Study on phase separation characteristics of gas-liquid mist flow in T-pipe [J]. China Petroleum Machinery , 2021 , 49 ( 9 ): 122 - 128 .
Ji Jian , Fu Xiaoning , Wang Yi , et al . Numerical simulation analysis of leakage flow field characteristics of gas-liquid two-phase flow pipeline [J]. Science Technology and Engineering , 2021 , 21 ( 1 ): 144 - 151 .
Xiong Zhiyi , Zhang Yun , Zhang Liwen , et al . Numerical simulation on gas-liquid two-phase fluid in coal-bed methane wellbore [J]. Journal of China University of Petroleum (Edition of Natural Science) , 2023 , 47 ( 2 ): 153 - 159 .
Qiu Xiaoxue , Zhong Guanghai , Li Xiansheng , et al . CFD simulation of flow characteristics of shale gas horizontal wells with different inclination [J]. Petroleum Reservoir Evaluation and Development , 2023 , 13 ( 3 ): 340 - 347 .
Zhang Xuliang , Zhang Chi , Zhou Bo , et al . Numerical simulation of gas-liquid two-phase flow pattern in large annulus of deep well [J]. Petroleum Drilling Techniques , 2024 , 52 ( 6 ): 37 - 49 .
Beggs H D , Brill J P . A study of two-phase flow in inclined pipes [J]. Journal of Petroleum Technology , 1973 , 25 ( 5 ): 607 - 617 .
Aziz K , Govier G W . Pressure drop in wells producing oil and gas [J]. Journal of Canadian Petroleum Technology , 1972 , 11 ( 3 ): 38 - 48 .
Mukherjee H , Brill J P . Liquid holdup correlations for inclined two-phase flow [J]. Journal of Petroleum Technology , 1983 , 35 ( 5 ): 1003 - 1008 .
张立胜 . 气液两相管流的实验研究及瞬态数值计算 [D]. 武汉 : 武汉大学 , 2020 .
Zhang Lisheng . Experimental research and transient simulation of gas-liquid pipe flow [D]. Wuhan : Wuhan University , 2020 .
He Huiqun , Ming Ruiqing , Rui Qunying , et al . Evaluation and optimization of pressure drop calculation models for CT drainage gas recovery [J]. China Petroleum Machinery , 2018 , 46 ( 10 ): 49 - 54 .