Research On The High Gas Rate Multiphase Flowmeters Based On Multi-sensors

Multiphase flow exists widely in chemical, petroleum, electricity and other fields,especially in the oil industry, from crude oil extraction, transportation, processing of crude oil are closely related with the multiphase flow, therefore, high-precision measurement of multiphase flow significant. However, due to the complexity of multiphase flow pattern, composition changing, now has the practical value of the multiphase flow meter is still small.With the exploitation of gas well, high gas content measurement of multiphase flow research in the field become one of the key issue. In recent decades, scholars from various countries working hard to study multiphase flow, but most of these studies for soft drinks or low void fraction two-phase two-phase flow to establish some model of high gas multiphase flow often exist when computing the total flow rate and low precision phase flow problems, can not meet the site requirements.As many a lot of crude oil associated gas in the past, methods such as Coriolis mass flow meter is not working properly bring huge measurement error. In this paper, using multi-sensor combination of measurement methods, Multi-sensor integrated measuring method in theory can solve the problem of high containing gas rate. Use sensors to three physical parameters of multiphase flow (dielectric constant, conductivity and rf absorption rate), established three equations and be a formula simultaneous into equations of each phase, the calculated in points rate; Then measured by related law of fluid flow (gas phase velocity and liquid velocity), and phase points rate multiplication, concluded that every phase flow. This paper deduced multi-phase dielectric constant, conductivity, rf absorptance formula, Capacitance measurement modules for some design AD7746 and FPGA chips based on the measurement circuit composed; To set values for the tiny capacitors made static testing; Calculating the capacitance sensor, and design the Labview virtual instrument based on environmental program and the computer to carry on the serial communication with different proportion of oil and gas, the measurement of gas rate, the measured results in PC display.Experimental results show that for small capacitance value has high accuracy,accurate to 4fF; For containing gas rate of oil and gas in 80 percent below two phase measurements more satisfied. In addition the scheme has wide measuring range, small size, high precision and low costs, the experiments show this method has a certain practical value, the study of multiphase flow meter offers a new way.