气井涡流携液机理和携液效率数值模拟研究

Numerical Simulation on Fluid-carrying Mechanism and Efficiency of Vortex Flow in Gas Wells

针对目前气井涡流携液机理和效率认识不清,现场工程设计与分析主要依据经验,影响应用效果等问题,运用Auto CAD和Fluent流体模拟软件,建立了涡流工具气液两相流场模型,分析了气液混合物通过涡流工具前后的流动轨迹、流型变化特征和携液效率变化规律。研究结果表明,涡流工具将气液两相雾流转换为螺旋环流,液体以液膜形式沿管壁螺旋向上流动,而气体在油管中心以更高的速度流动。这种流态能够降低流动过程中的压力损失24.3%,提高流体速度13.5%,减小持液率3.3%,减弱气液两相之间的滑脱,提高气体携液能力。研究结果为涡流工具有效解决气井开采初期井底积液,提高地层能量利用率,以及延长气井自喷期提供了理论依据。

At present, there is still no clear understanding on the mechanism and efficiency of vortex flow in gas wells. Field engineering design and analysis is mainly based on experience, which influences the application effi- ciency of vortex tools. In order to solve these problems, the AutoCAD and Fluent software are applied to establish a gas-liquid flow field model. With this model, flow track, variation of flow pattern and fluid-carrying efficiency of gas- liquid mixture through vortex tools are analyzed. The research results show that the flow pattern is transformed from gas-liquid mist flow into helical annular flow by vortex tools, liquid moves upward spirally along the tubing wall in a liquid membrane way, and gas moves in the center of the oil tubing at a higher speed. This flow status lowers pressure drop by 24. 3%, increases flow rate by 13.5% and decreases liquid holdup by 3.3% during the flowing process, which will weaken slippage between gas and liquid, and enhance fluid-carrying ability of gas. The results will provide theoretical basis for solving problems of liquid loading at the bottom of gas wells at initial stage of production with vortex tools, improving formation energy availability and extending the natural flow period of gas wells.