Research progress of critical gas velocity prediction model for liquid accumulation in natural gas pipeline

The normal operation of natural gas gathering and transportation system is strongly affected by the liquid accumulation in pipelines, a common phenomenon in gas field development. Available prediction of liquid accumulation is helpful to take timely measures to reduce the harm caused thereby, and the calculation of critical gas velocity is crucial to the prediction of liquid accumulation in pipelines. The related research on prediction of critical gas velocity in pipeline was reviewed, and the limitations of minimum pressure drop model and droplet model were pointed out, with the liquid film model being provided with better applicability. Depending on the actual situation of pipeline liquid accumulation, the keys to apply the existing research achievements of pipeline liquid accumulation to production practice are as follows: selecting the pipeline liquid accumulation criteria suitable for different situations, reasonably characterizing the circumferential distribution of liquid film in pipelines at different slope angles, taking into consideration of the gas-liquid flow characteristics of large-size wet gas pipelines under complex terrain conditions, and adopting reasonable interface friction coefficient calculation formula.