定向气井临界携液流量预测新模型

A new prediction model for critical liquid-carrying flow rate of directional gas wells

针对定向井气体携液机理不清、临界携液流量预测误差较大等问题,基于定向井筒中液膜的受力状况,考虑气芯与液膜之间的剪切力、液膜与管壁之间的剪切力、流体重力和液膜前后的压差等作用,建立了定向气井临界携液流量预测模型,并推导了该预测模型相对于Turner模型的修正系数。敏感性分析结果表明,修正系数主要与油管内径和井斜角有关,受管壁摩擦系数的影响较小;同时还给出了修正系数速查表,以便于实际中使用。现场实例计算分析结果表明：①所建立的预测模型计算误差小于5%,与定向气井临界携液流量常用计算模型相比,计算精度提高10.03%～48.72%;②计算结果与现场生产实际更加吻合,可准确地预测定向气井的临界携液流量。该研究成果对定向气井合理配产、携液动态预测具有指导意义和实用价值。

In order to understand the liquid-carrying mechanism of directional gas wells and reduce the prediction error of critical liquid-carrying flow rate, we established a new model which could predict the critical liquid-carrying flow rate of directional gas wells by analyzing the force on liquid film in directional boreholes, including the shear force between gas column and liquid film, the shear force between liquid film and inner wall, and the gravity and the pressure drop along liquid film. Then, a correction coefficient between this prediction model and Turner model was derived. It is shown from sensitivity analysis that the correction coefficient is mainly influenced by tubing 1D （intemal diameter） and deviation angle, but less influenced by pipe friction factor. Furthermore, a look-up correction coefficient table was given for the convenience in practical application. It is indicated from the case calculation analysis that the calculation error of this prediction model is less than 5% and its calculation accuracy is 10.03 48.72% higher than that of other common models for liquid-carrying flow rate of directional gas wells. The calculation result of this model is more consistent with practical production data. It is demonstrated that the liquid-carrying flow rate of directional gas wells can be predicted accurately by using this new model. The research achievements in this paper are of vital guiding significance and practical value in reasonable proration and liquid-carrying dynamic prediction of directional wells.