Study On By-pass Pigging In Wet Gas Gathering Pipeline Under Complex Terrain Conditions

In the wet gas gathering pipeline,the decline of temperature and operating pressure contributes to the generation of condensate in the pipeline.In complicated mountain gathering pipeline,liquid in gas pipeline will reduce the effective transfer area and increase resistance.As a result,it will reduce pipeline transfer efficiency significantly,aggravate pipeline corrosion,increase the leaking risk,and produce hydrates under certain pressure and temperature which may cause ice barrier.One effective method is pigging regularly.However,there are some disadvantages when using regular pigs,such as liquid accumulation in the downstream of pig,terminal pressure fluctuation,increase of slug catcher level,and large pig velocity.Thus it is of significance to develop new by-pass pig.Based on studying the structure of home and aboard pigs,the by-pass pig applied in wet gas gathering system is designed reasonably.Through controlling the regime of pig downstream,the pig velocity,terminal pressure fluctuation and slug catcher level fluctuation are decreased,which reduce the pigging risk.Fluent is used to simulate the flow field of by-pass pig operated in horizontal pipe and hilly pipe.The flow field of pig tail plate in different opening situations is studied.Numeral simulation software is utilized to simulate the by-pass pig operating condition in indoor loop and M503-M502 pipe.This paper compares the pigging effect of by-pass pig in different velocity,pressure and slug flow.The relationship between pigging effect and by pass rate is also studied.According to the simulation result,the flow field in the operation is analyzed which can provide theoretical base for laboratory experiment and field apply.Ultrasonic echo signal attenuation characteristics is different in gas-fluid and fluid-solid interface.Combined with high sulfur content in puguang gas field,in order to prevent the leakage of hydrogen sulfide from leading poisoning accident,we achieve non-intrusive measurement instead of changing pipeline structure and destroying detection of liquid loading volume.We propose non-invasive way with the ultrasonic echo to test the gas liquid in non-liquid loading in the outer wall of the tube.We research and develop ultrasonic fluid monitoring device to carry out laboratory tests.Ultrasound probe monitors at different positions.Two different positions in the gas liquid interface,the echo intensity is different after several attenuation,so we can determine the height of the liquid loading.