Analysis Of The Key Factors Affecting The Accuracy Of Water Cut Measurement Of Crude Oil By Radio Frequency Method

The water cut of crude oil is an important parameter for the implementation of intelligent production in oil field,which has a guiding role in the production process of water injection well.According to the measurement of water content,the best mining strategy of each production layer can be formulated,and the mining plan can be adjusted to meet the needs of multi reservoir optimal mining.The accurate measurement of water cut of crude oil is the solid foundation of intelligent completion technology such as layered production,layered testing and layered control.The purpose of this paper is to analyze the key factors that affect the accuracy of water cut measurement of crude oil by RF method.Based on the electric field characteristics of high frequency electromagnetic wave propagating in oil-water medium,the problems of traditional measurement model based on monopole parallel dual antenna are analyzed,and the water content measurement model based on spiral antenna structure is proposed.The electromagnetic field changes of spiral antenna structure in oil-water medium with different water content ratio are simulated by using COMSOL multi physical field simulation software,The feasibility of the water cut measurement model of the spiral antenna structure is verified,and the measurement range and sensitivity of the water cut are improved;the structure of the measurement device is optimized to make the water cut measurement instrument more suitable for the field conditions of the oil field;and the nonlinear compensation algorithm is designed according to the displacement characteristics of the dielectric constant of the fluid characteristics,which reduces the error of the water cut measurement.The modules of the water content measurement circuit system are debugged in cascade,and the RF signal source,modulation and demodulation,data communication and other circuits are improved,so that the water content measurement device can work stably in the high temperature and high pressure underground environment.The indoor cycle test platform was built and the water content measurement experiment was carried out.The experimental results show that the measurement error of water content in the whole range is less than 5%.The water cut measuring instrument has been tested in the field pipeline of oil field.The field application shows that it is stable,reliable and fast in response.The instrument provides reliable measurement data for digital oil field and intelligent completion technology.