油-气-水三相流水平井携液临界气量计算方法

川西中浅层水平井不同程度产液，当气井积液时，需实施泡排等工艺技术排液后才能稳产，而判断积液最简单的方法是计算气井携液临界气量，气井携液临界气量计算常用液滴或液膜模型，此两种模型均基于液滴或液膜反转作为判断积液标志而建立，应用结果与实际符合率较低。针对以上问题，开展了水平井积液规律模拟实验及相关模型研究，结果表明，液滴或液膜反转时，井筒均未积液，以液滴或液膜反转判断积液建立的模型计算的积液时间比实际偏早，进而基于实验现象，分析气体带液能力，建立新的气井积液判断标准；倾斜段携液临界气量随井斜角度的变化先增加后减少，40°时携液临界气量最大；基于实验测试数据，考虑含油率、井斜角对携液临界气量的影响，建立了携液临界流量计算模型，应用于中浅层水平井油—气—水三相流井筒积液判断，符合率91.4%，在同类气井具推广应用价值。

Method for Calculating Critical Liquid Carrying Flow Rate of Oil-gas-water Three-phase Horizontal Wells

Horizontal wells located in medium-shallow layers of western Sichuan produce fluids to varying extents. When wells suffer from liquid loading, engineers must implement foam assisted lift or other technologies to stabilize the production. The easiest way to recognize liquid loading is to calculate the critical gas flow rate of gas wells. Two commonly used models for critical liquid carrying flow rate calculation are droplet and liquid film models, and the two models are established based on droplets or liquid film reversal as the onset of liquid loading. However, the result by the two models do not match well with observations in gas wells is low in the research area. To solve this problem, experimental investigation on liquid-loading behavior in horizontal gas wells and corresponding modeling study have been conducted. The results indicate that liquid is not yet loaded in wellbore when the droplets or liquid film are reversed. Therefore, predicted liquid-loading onset by the two models is too conservative. Then, a new criterion of liquid-loading onset is proposed based on the observed flow phenomenon and dragging capability of gas core. With the decrease of inclination, the measured critical gas flow rate increases first and subsequently decreases, reaching maximum at inclined angle of about 40°. Based on measured data and considering the effect of oil cut and inclined angle, a new liquid-loading predicting model was established. The new model was applied to prediction of liquid loading in wellbore of horizontal wells in the medium-shallow layers with oil-gas-water three-phase flow. The accuracy of the new model is 91.4%, suggesting that it is worth promoting and applying in similar gas wells.