This work attempts to identify the characteristics of gas and liquid transport under different horizontal borehole trajectories in order to promote the efficient production of coalbed methane (CBM). The software Fluent was applied to simulate the two-phase gas and liquid transport under different horizontal sections of borehole trajectories, and the gas-liquid transport features under four types of horizontal section borehole trajectories (upward inclined, downward inclined, bow shaped, and spoon shaped) were obtained. We also analyzed the retention effects of liquids in the horizontal section under the four types of borehole trajectories, and proposed the drainage and production technology for efficient gas and liquid production. The results show that under different gas-liquid flow rate ratios, there were flow states in the upward inclined wellbore trajectory, including bubble flow, laminar flow, and annular mist flow. These flow states such as bubble flow, laminar flow, slug flow, dispersed flow, and annular mist flow were observed in the downward inclined and bow shaped wellbore trajectories. There were laminar flow, slug flow, and annular mist flow in the trajectory of the spoon shaped wellbore. The liquid retention intervals for the four types of wellbore trajectories, namely upward inclined, downward inclined, bow shaped, and spoon shaped, were 670~700 m, 0~300 m, 0~180 m, 650~700 m, and 0~320 m, respectively. The proportions of retention areas were 4.28%, 42.86%, 32.86%, and 45.71%, respectively. During annular mist flow, the gas carrying effect can promote liquid production and reduce the retention effect of liquid. When the gas-liquid flow rate ratio was 6.667, it can transition from slug flow to annular mist flow. During the gas production stage of coalbed methane wells, by adjusting the casing pressure and bottomhole flow pressure in the actual production process, the daily gas production of coalbed methane wells can be rapidly increased, which can achieve efficient production of gas and liquid. This research result can provide a theoretical basis for the CBM drainage and production wells in different horizontal wellbore trajectories during the gas production stage.

horizontal section borehole trajectory  /  gas and liquid transport characteristics  /  retention effects of liquids  /  drainage and production technology  /  coalbed methane