Abstract:

With the production of the Puguang gas field, low-liquid-loading gas-oil two-phase flow present in wet gas pipelines is one of the typical occurrences of three-phase flow in the oil and gas industry.Wet gas transportation pipelines often contain water and hydrocarbon condensates, which leads to the occurrence of low-liquid-loading three-phase flow.However, small amounts of condensates can lead to a significant increase in pressure drop along a pipeline.In-situ liquid holdups are important for determining pigging frequency and designing receiving facilities.The development of a hydrodynamic model for the wet gas gathering pipelines has become a key problem.According to fluid hydrodynamics, a hydrodynamic model for complex terrain was developed, and the closure correlationships corresponding to the model were given, which was suitable for the calculation of the low-liquid-loading two-phase flow in pipelines.The indoor test was done to verify the pressure and liquid holdup calculations.With the experimental data, the gas-wall friction factor, gas-oil interfacial friction factor and gas-liquid interface shape relationships were optimized, and a new gas-oil interfacial friction factor combined relationship and gas-liquid interface shape was established. By the comparative analysis of calculation model and experimental data, the proposed flow pattern criteria and the model for liquid holdup and pressure gradient were validated.The field production results were also collected to test the calculated results of the model.The pressure results were in the relative  error ±5%, the accumulated liquid results were in the relative error ±10%, which agreed fairly well with the production data.The developed model can be used for low-liquid-loading calculation.