Modeling of Gas Migration in Large Elevation Difference Oil Transmission Pipelines during the Commissioning Process

Oil pipeline construction and operation in mountainous areas have increased southwestern China, with oil consumption increasing. Such liquid pipelines laid continuously undulate along the terrain, resulting many large elevation difference pipe segments. Serious gas block problems often occur during commissioning process of these due to gas/air accumulation at high point pipe, which causes overpressure vibration, even safety accidents such as bursting pipes. To solve this problem, gas–liquid replacement model its numerical solution are established consideration initial formation segment compression processes a U-shaped start-up operation. Additionally, considering interactions gas-phase transfer continuous influence length, inclination angle, backpressure on air vent process, migration for is predict movement process. Finally, field production data were applied verify model. The results demonstrate that maximum deviation between calculated pressure real 0.3 MPa, critical crushing section about 0.2 Mpa. show mass multi-pipe hydraulic increase downstream pipe. This study’s achievements can provide theoretical guidance technical support safe stable undulating drops.