Design And Research On Optical Fiber Probe Void Fraction Meter Used In Oil-gas-water Three Phase Flow

Oil is one of the most important energy sources in the modern world, It plays a pivotalrole in society development and economy construction process. However, as the deepening ofdomestic oilfield development, The flow characteristic of the oil well output profile hassignificantly changed, Multiphase flow phenomenon become increasingly common. Thissituation lead to existing producing liquid profile measuring instruments and technology cannot adapt to the new test environment. Currently, there are several methods like ray method,supersonic method, high-speed photography method measuring void fraction in and abroad,but every method has its own limitation. However, when using optical fiber-probe sensor, theinformation carrier is light and has no relation with the resistivity and dielectric constant ofthe mixed flow, it can also achieve multipoint and multi-aspect distributed measurement, andhas strong anti-interference ability, and can working in the oil well for a long time, etc.Considering the merits of the optical fiber-probe sensor, the research of oil-gas-water voidfraction measurement based on fiber sensor has important significance.This thesis detailed why we have chosen the double-fiber coned probe structure, we usedmanual grinding method to made the probe; according to the complexity of environmentwhere the void fraction measuring instrument be used, we carefully selected light source,photoelectric detection device, designed and made fiber sensor circuit and inverting inputprecision rectification circuit; we programmed the sensor testing program. Testing datashowed when there was no light illumination, the output data was voltage signal about225V;when there was light illumination, the output data was0. Testing result indicated the sensorwe made has high sensitivity, and could be used in next experiment.In this study, a simple equipment in our lab has been built to measure void fraction ofoil-gas-water three phase flow. Under the condition that oil, gas were static, the proportion ofoil, gas was1:1, I did several experiments to measure the oil-gas-water void fraction whengas to liquid ratio was different as5%,10%,15%,20%,25%,30%. In measuring progress,measuring results can real-time display on the interface based on C#software.Though error analysis between known value and measured value, we learned that thevoid fraction error measured with the instrument I made was controlled in5%.