气水两相下降流中泡状流与段塞流转换边界研究

Study on the Transition Boundary between Bubbly Flow and Slug Flow in Gas-Water Two-Phase Descending Flow

针对塔河油田气水混注驱替“阁楼油”过程中泡状流与段塞流转换边界不清的问题,利用数值模拟方法对气水两相下降流中泡状流与段塞流进行了模拟分析。结果表明:在气相表观流速为0.01~1.00 m/s、液相表观流速为0.03~2.00 m/s、管径为76 mm的模拟条件下,管道中主要为泡状流和段塞流;与模拟结果相比,Barnea、Kokal、薛玉卿模型预测的转换边界偏小,Bhagwat和Yijun模型预测的转换边界偏大;随着气相表观流速增加,泡状流向段塞流转换时所需液量逐渐增大;在低液量条件下,越靠近管道中心,气泡数量越多,空隙率越大;随液量增加,单个小气泡体积减小,气泡在整个管道横截面上分布越均匀。基于漂移模型,考虑气泡群滑脱速度,建立了新的泡状流与段塞流转换边界模型,216组文献数据验证结果显示,新模型准确率为95.37%,准确度较高。建立的泡状流—段塞流转换边界模型,不仅可提高井筒压力、温度模型的计算精度,同时对塔河油田现场注入井井口参数优化、注入设备优选和提高“阁楼油”驱替效率有很好的理论指导意义。

To address the problem of unclear transition boundary between bubbly flow and slug flow in the process of gas-water mixed injection to displace the"attic oil"in the Tahe Oilfield,the numerical simulation method was used to simulate and analyze the bubbly flow and slug flow in the gas-water two-phase descending flow.The results show that:under the simulation conditions of gas-phase apparent flow rate of 0.01-1.00 m/s,liquid-phase apparent flow rate of 0.03-2.00 m/s,and pipe diameter of 76 mm,the pipeline is mainly characterized by bubbly flow and slug flow;compared with the simulation results,the transition boundary predicted by the Barnea,Kokal,and Xue Yuxing models is small,and that predicted by the Bhagwat and Yijun models is large;with the increase of the gas-phase apparent flow rate,the liquid volume required for the transition from bubbly flow to slug flow gradually increases;under the condition of low liquid volume,the closer to the center of the pipeline,the higher the number of bubbles and the larger the void ratio;with the increase of liquid volume,the volume of individual small bubbles decreases,and the more uniformly the bubbles are distributed throughout the cross-section of the pipeline.Based on the drift model,a new bubbly flow-slug flow transition boundary model was established by considering the bubble group slipping velocity,and 216 sets of literature data validation results show that the accuracy of the new model is 95.37%,which is high.The established bubbly flow-segment plug flow transition boundary model cannot only improve the calculation accuracy of the wellbore pressure and temperature model,but also has a good theoretical significance for the optimization of wellhead parameters,the selection of injection equipment,and the improvement of the efficiency of"attic oil"displacement in the field of Tahe Oilfield.