Study On Flow Measurement Technology Of Multiphase Flow Frequency Difference Method

After the oilfield has entered the secondary and tertiary oil recovery stage,the contradictions between the layers are prominent,the water content of the production layer rises,the water source is unknown,and it is difficult to plug the water.The combined production cannot fully utilize the recoverable reserves of the oil layer and cannot improve the recovery rate.Therefore,accurately figuring out the water cut and single-layer production parameters of a monitoring well in a mining block is the primary task for the oilfield to implement stratified oil production at present.By regulating the flow rate of each layer,the recovery factor can be improved.The thesis combines the characteristics of downhole oil-water mixed fluid and the working environment,combined with the technical advantages of ultrasonic in the field of fluid detection,so this paper uses the ultrasonic time difference method to measure the fluid flow,and provides the required flow parameters for the flow adjustment in the stratified oil recovery.Due to the complex factors that affect the accuracy of ultrasonic flow measurement downhole,this article mainly studies the impact of downhole ambient temperature and sensor operating frequency on the measurement accuracy.First,the COMSOL software is used to simulate and analyze the propagation and attenuation characteristics of the ultrasonic waves emitted at different frequencies in different oil-water ratio media,which is a necessary reference for selecting the best operating frequency value.Secondly,it analyzes the cause of flow measurement error caused by the temperature change of the working environment,and provides a theoretical basis for subsequent digital signal processing and compensation.Combined with the theoretical knowledge of flow regulation,the shape of the water nozzle,the structure of the control valve and the control method in the regulation system are analyzed.According to downhole conditions and fluid characteristics,a set of more accurate and effective flow adjustment structure is designed,and PID control technology is used for motor control,which can improve the response speed and control efficiency,and finally realize the purpose of real-time flow adjustment.Use the indoor simulation system to test and analyze the designed downhole flow measurement and regulation system.First of all,the temperature and pressure test of the measurement and adjustment system is carried out,and its performance meets the design requirements.Secondly,the flow measurement and flow adjustment effect are tested.According to the test data,the measurement error can reach 5% and the adjustment efficiency can be kept within 5%.Therefore,the flow measurement and adjustment system has many auxiliary effects on the stratified oil recovery process.