The Technical Research Of Multi-channel Energy Spectrum Analysis Based On X-ray

In order to measure the phase holdup of oil and gas water phase,the principle of X ray multichannel energy spectrum analysis is studied,and an equivalent model of oil-gas-water three phase flow is established in this paper.According to the attenuation law of X ray transmission medium,the formula for calculation of oil,gas and water content is derived.The Monte Carlo simulation software MCNP5 is used to simulate the actual oil and gas water three phase flow model,and the oil gas and water content is calculated according to the derived formula,then the calculation results are analyzed.The system mainly consists of X ray generation part,which is composed of high voltage source,filament current source and X ray tube,and X ray detection and multichannel spectrum analysis part.The high voltage source provides the DC high voltage between the two poles of the X ray tube,the filament current source provides the filament current to produce the electron,the tungsten target and the molybdenum target X ray tube are selected to produce the high and low two levels of X rays.The high voltage source adopts the full bridge resonant converter and the multiple voltage rectifier circuit as the main body,and combines the feedback control circuit to output stable DC high voltage.The filament current source adopts Buck switch power supply structure,and combines sampling and feedback circuit to output stable current.Through testing the actual X ray tube,the high voltage source can output the highest 80 kV adjustable DC voltage,and the filament current source can output 0.8 to 2.0A current,which meets the requirements of X ray generation.X ray detection and multichannel energy spectrum analysis part are used for X ray reception and processing,then X ray multichannel data are obtained.The NaI crystal detector receives the X ray light signal and convert it into the voltage signal outputted,the voltage signal is amplified to the appropriate input voltage of the ADC(analog to digital converter)by the signal regulating circuit,then the analog signal transfered to FPGA is digitized by ADC,the multichannel energy spectrum data is obtained by digital signal processing and stored in the dual port RAM in FPGA.The data in the dual port RAM is readed,displayed and stored by ARM,then sent to the upper computer for further processing to obtain the phase volume fraction of oil-gas-water three phase flow.The simulation system of oil-gas-water three phase flow is built in the laboratory.Six tests are carried out under the same oil and gas water fraction.The results show that the designed system can measure the fraction of oil,gas and water phase,and the absolute error is less than 4.1%.It proves the feasibility of the system and provides a solution for the measurement of the fraction of oil-gas-water three phase flow in the petroleum industry.