The Development Of Vortex Flowmeter Of Supercritical Carbon Dioxide Used In Oilfield Downhole With Special Shaped Pipe

Vortex shedding flowmeter uses fluid vibration to measure the flow.Due to its simple structure,easy maintenance and many other advantages,vortex shedding flowmeter plays an important role in the fields of petroleum,chemical,power and other industries.Due to its advantage in structure,the measurement performace in tiny-diameter pipelines of vortex shedding flowmeter with abnormity cross section exceeds the ordianary one.However,lots of problems remain,especially on the condition of lower flow rate,vortex flowmeter is influenced by many kinds of interference noises,signal-to-noise rate is low and measurement is hard to realize,which cause the measurement lower limit is rather higher in applications and range ratio of simulated vortex is only 1:10,much further away from the theoretic range ratio of 1:100.Most of researches mainly focus on the vortex flowmeter of larger diameter and circular cross section,flowmeters of tiny diameter and abnormity cross section are rarely involved.Based on abnormal section pipe and the requirements of qualifiedflow,a narrow-diameter-pipe vortex flowmeter is designed for measuring mass flow of supercritical carbon dioxide.Meanwhile,The real flow experiments are designed and carried out.The research is completed as following:1.According to the requorements of limited flow rage of profiled pipe flowmeter flow calculation of the lower limit is carried out,and based on the pipe size set,the simulation test and verify are conducted.And then comparing the simulation data with theoretical data,futher optimize size will be received.2.For the measurement of supercritical carbon dioxide quality flow rate,in this project Peng-Robinson formula is used to do density compensation to supercritical carbon dioxide flow rate measurement,the disadvantage that traditional density compensation method can not fit the wide range of changes in industrial conditions and satisfy the precision demand is overcome,measurement precision is raised,which makes vortex flowmeter fit the range of supercritical carbon dioxide quality measurement and extends the application range of vortex flowmeter.3.The hardware design and software design are finished,and the mass flow measurement of supercritical carbon dio xide is realised.Meanwhile it can achieve a lower range limit,broaden the range ratio,and meet the requirements of the project.4.The vortex flowmeter of supercritical carbon dioxide designed in this paper is used for oil well measuring,and can adapt to the environment of high temperature and high pressure.The whole system has high reliability and stability,low power consumption and short processing time.What is more,the water flow test in Tianjin University experimental flow device,ground test and simulated experiment in Dongying have been conducted,and oilfield downhole field experiment is on the schedule.