Research On Measurement Method Of Water Content By RF Method In Oil-water Two-phase Spiral Flow

The water content of crude oil is an important index to measure the productivity of an oil well,to evaluate the production value of its reservoir,to evaluate the utilization rate of its reserve,and to draw up the development plan.On-line measurement of water content is very important for determining the reservoir of various oil well products and predicting the production life of various oil Wells.At the same time,accurate and timely online measurement data of water content from crude oil can truly reflect the performance of oil Wells,and it is of great significance to realize automatic management in the production process of oil fields in China.At present,the water content testing methods commonly used in China's petroleum industry mainly include manual sampling and distillation testing.The sampling time is long,the randomness is large,and can not be operated online.This method is time-consuming and laborious,and can not fully meet the needs of production and automatic management of oilfield enterprises.Though various types of oil water cut meter have been developed,and has obtained some research results in the oil business,but due to reasons such as process flow and technical level,they are in the process of production stability,accuracy,real-time,reliability and cost,etc,it is difficult to meet the high water content oil field production needs in the practical work.In view of the characteristics of high water cut in oil fields in China,this paper designs a water cut sensor based on radio frequency method under swirling state.Through the design of oil-water on-line separation structure,the dielectric constant of oil-water mixed phase can be measured simultaneously.Real-time water cut measurement can be realized in the whole process of oil production.It can adapt to the oil-water mixing stage under different geological conditions and different degrees of mineralization,eliminate the influence of uneven oil-water distribution in different well water cut measurement results,have better reliability and accuracy,and play a positive role in adjusting production plans and improving crude oil recovery.The main contents and conclusions are as follows:(1)Through the antenna simulation software HFSS,the rod antenna matching with the experimental system is designed,and the parameters of the antenna are optimized,as well as the casing and cyclone are optimized.(2)The model of two-phase flow in the swirling state was deduced,and the corresponding relationship between water content and measured data in the circuit was obtained,which provided a theoretical basis for static calibration tests.(3)Analyze and design the realization of the hardware circuit,complete the software writing of MCU and upper computer,and realize the real-time control,transmission and display of data.The speed and precision of hardware processing are improved.(4)The static calibration and dynamic test of oil and water were carried out on the whole experimental system.After a large number of experiments,the experimental data were analyzed and studied,and the errors in the data were optimized accordingly.The two-phase flow velocity slip model was used to modify the parameters to make the measurement results more accurate.The method can eliminate the influence of the uneven distribution of oil-water two-phase flow pattern on the measurement results and expand the measurement range of water content.The experimental results show that when the inlet oil/water two-phase mixing flow rate is 0.60?1.20m/s and the volume moisture content is higher than 43.81%,the measurement error of water content using this method is less than 5.68%.