Study on the Characteristics of Gas–Liquid Two-Phase Flow in Shale Gas Horizontal Wells—Taking Changning Block as an Example

At present, more than 50% of the horizontal wells in Changning block have entered the middle and late stage of low gas production, and the gas is difficult to produce with liquid. For such gas wells with a complex wellbore structure, multiple wellbore flow patterns and complex pressure distribution, the corresponding gas–liquid distribution characteristics and liquid carrying capacity are not yet mature. Therefore, based on the establishment of a large-scale experimental simulation device for air–water two-phase flow in horizontal wells with a horizontal section–inclined section–vertical section, this paper studies the gas–liquid distribution characteristics and liquid carrying capacity of shale gas horizontal wells through gas–liquid two-phase flow experiments. The variation and distribution characteristics of gas–liquid two-phase flow pattern in horizontal wellbore are mastered. When the gas flow rate in the horizontal section is less than 20 m3/h, and the gas flow rate in the vertical section and the deflecting section is less than 30 m3/h, churn flow occurs and effusion occurs. It is found that the deflecting section of each well section is the most difficult to carry liquid, and the horizontal section is the easiest to carry liquid. When the critical carrying liquid is in the horizontal section, the vertical tube accumulates liquid, and the oblique section accumulates liquid simultaneously. This result is not only crucial to improve the production of gas wells in Changning block but also provide guidance for the production of shale gas horizontal wells in the middle and late low gas production stages.