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闫 晋,倪小明,郭盛强,等. 天然气储层裂隙中气−液两相流的流态转变条件数学模型[J]. 煤炭科学技术,2024,52(6):155−164. doi: 10.12438/cst.2023-1054
引用本文: 闫 晋,倪小明,郭盛强,等. 天然气储层裂隙中气−液两相流的流态转变条件数学模型[J]. 煤炭科学技术,2024,52(6):155−164. doi: 10.12438/cst.2023-1054
YAN Jin,NI Xiaoming,GUO Shengqiang,et al. Mathematical model for flow regime transition conditions of gas-liquid two-phase flow in natural gas reservoir fracture[J]. Coal Science and Technology,2024,52(6):155−164. doi: 10.12438/cst.2023-1054
Citation: YAN Jin,NI Xiaoming,GUO Shengqiang,et al. Mathematical model for flow regime transition conditions of gas-liquid two-phase flow in natural gas reservoir fracture[J]. Coal Science and Technology,2024,52(6):155−164. doi: 10.12438/cst.2023-1054

天然气储层裂隙中气−液两相流的流态转变条件数学模型

Mathematical model for flow regime transition conditions of gas-liquid two-phase flow in natural gas reservoir fracture

  • 摘要: 气−液两相在储层裂隙中流动时可能存在气泡流、段塞流、环雾流等流态,查明流动时流态转变条件能为气−液两相流流态形成机理研究提供依据,有助于天然气井的生产管控。根据气−液两相流不同流态的流动特点,结合连续介质控制理论和动量守恒原理,构建了气泡流−段塞流−环雾状流等流态之间转变的数学模型,确定了各流态间变化的临界条件和主控因素,通过气−液运移产出微观流动物理模拟试验验证了所建数学模型的准确性。结果表明:气−液两相在裂隙中的流态转变是气/液相的物理性质、注气通道孔径、裂隙流动通道孔径、气相流体流速、液相流体流速等因素耦合作用的结果。气泡流与段塞流能否转变主要取决于初生气泡大小、流动通道空间、液相界面波高度;段塞流与环雾流间能否转变取决于气相流体能否击碎液相流体并使之悬浮。不同流态间转变的主要控制因素不同:气泡流与段塞流相互转变的主控因素为裂隙系统的孔径,注气通道孔径越大、流动通道孔径越小,越容易发生段塞流;段塞流与环雾流相互转化的主控制因素为流体流速、气/液相流体的物理性质,气/液相对速度越大、气/液密度差越小、液相表面张力越小,越容易发生环雾流。研究成果能够为天然气储层裂隙中气−液两相流态形成机理和天然气运移产出研究提供理论依据。

     

    Abstract: The flow of gas-liquid two-phase flow in reservoir fractures may exhibit various flow regimes, such as bubble flow, slug flow, and annular mist flow. Identifying the conditions for the transition between these flow regime is essential for understanding the formation mechanism of gas-liquid flow and has significant implications for the production pipeline management of natural gas Wells. Based on the flow characteristics of different flow regimes of gas-liquid two-phase flow, combined with the theory of continuous medium control and the principle of momentum conservation, transformation mathematical models between flow regimes such as bubble flow, slug flow, and annular mist flow were established. The decisive conditions and key controlling variable that govern the transitions between various flow regimes have been precisely identified. Furthermore, the precision of the mathematical model was rigorously validated through microscopic physical simulation experiments focused on gas-liquid transportation. The results indicated that, the flow state transition of gas-liquid two-phase flow in fractures was the result of the coupling effect of factors such as the physical properties of the gas/liquid phase, the pore size of the gas injection channel, the pore size of the fracture flow channel, the gas phase fluid velocity, and the liquid phase fluid velocity. The transition between bubble flow and slug flow mainly depended on the size of the initial bubble, the flow channel space, and the height of the liquid phase interface wave. The transition between slug flow and annular mist flow depended on whether the gas phase fluid can break down the liquid phase fluid and suspend it. The main control factors for the transition between different flow states were different. The pore size of the fracture system was one of the most important factors in the mutual transformation of bubble flow and slug flow, when the injection channel aperture was larger and the flow channel aperture was smaller, it was more likely to form slug flow. The mutual transformation between slug flow and annular mist flow was primarily influenced by fluid velocity and the physical properties of gas/liquid phase fluids. A higher relative velocity between the gas-liquid phases, a smaller density difference between the phases, and a lower liquid surface tension all increase the likelihood of forming annular mist flow. These research findings established a theoretical foundation for understanding the mechanism of gas-liquid two-phase flow formation in reservoir fractures and natural gas transport production.

     

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