SM气田气井普遍产水，导致井筒积液，需要进行排液。目前在积液预测方面的研究都比较难应用于实际生产中，且可推广性较差。采用数值模拟的方法模拟得到了SM气田井筒的临界携液流速，并将其推广到57口气井，且预测精度较高。基于MATLAB软件建立了3个高精度多相流瞬态井筒模型进行模拟分析。模拟结果表明，SM气田气井的临界携液流速为3.07 m/s左右；当气井流速大于临界携液流速时，井筒内各项流动参数很快达到稳态，且持液率在2.5%以下，认为此时不积液；当气井流速小于临界携液流速时，井筒持液率较高，且高持液率管段压力损失较多。根据此临界携液流速绘制出1.38 in（1 in = 2.54 cm）和1.61 in油管的临界携液流量图版。将该图版应用于现场，预测精度达89.5%，可用于指导现场排液工作。

Gas wells in the SM gas field generally produce water, resulting in liquid accumulation in the wellbore and the need for liquid drainage. Currently, studies on liquid accumulation prediction are rather difficult to be applied in actual production and have poor generalization. The critical liquid-carrying flow rate of the wellbore in the SM gas field was obtained through numerical simulation and extended to 57 gas wells, with relatively high prediction accuracy. Three high-precision multiphase flow transient wellbore models were established based on MATLAB software for simulation analysis. The simulation results indicate that the critical liquid-carrying flow rate of gas wells in the SM gas field is approximately 3.07 m/s. When the gas well flow rate is greater than the critical liquid-carrying flow rate, various flow parameters in the wellbore quickly reach a steady state, and the liquid holdup is below 2.5%, suggesting no liquid accumulation at this time. When the gas well flow rate is less than the critical liquid-carrying flow rate, the liquid holdup in the wellbore is high, and the pressure loss in the high liquid holdup pipe section is considerable. Based on this critical liquid-carrying flow rate, the critical liquid-carrying flow rate diagrams for 1.38 in(1 in = 2.54 cm) and 1.61 in tubing are plotted. When this diagram is applied to the field, the prediction accuracy reaches 89.5% and can be used to guide the on-site liquid drainage work.