Research And Design On Two-phase Flow Measurement Unit Over Real-time Cross-correlation Algorithm

Oil and gas are one of the most important resources in marine mineral resources.Submarine oil reserves accounted for nearly half of the global oil reserves,but due to the current technology is not yet mature,there are many technical problems to be solved,so the marine mineral resources has not been rational exploitation and full use.In recent years,countries continue to invest a lot of manpower and resources to exploit offshore oil resources.In order to reduce the pressure of fuel shortage.In order to achieve better control and planning of the oil and mining speed of each oil well,it is usually necessary to monitor the flow parameters such as oil and gas flow and flow rate in the pipeline during the development of submarine resources.The flow of resources in the well is usually a multiphase flow.The measurement of the multiphase fluid is mainly due to the measurement of the flow rate of each component in the fluid and the real-time measurement of the fluid velocity.First,in order to measure the flow parameters of each component in the fluid,taking into account the cost of mining,as far as possible the use of non-separable component measurement method,then the need to select the appropriate structure and size of the sensor,so that the sensor within the required range of precision The field has a relatively uniform induction.Secondly,in order to achieve real-time measurement of fluid flow rate,we need to optimize the measurement algorithm,and the corresponding selection of high-performance hardware,to improve the system speed.Aiming at the measurement demand of multi-phase flow,a double-screw plate capacitance sensor model is established.The error of the screw capacitive sensor does not exceed 2.5%.The measured fluid flow rate is usually between 20 m/s and 200 m/s.Process conditions are usually in the range of 10m3/d to 200m3/d,the pressure between 0.7Mpa to 2.0Mpa,the temperature between25 o C to 80 o C.The working principle and characteristics of the spiral capacitive sensor are expounded and analyzed,and the structural parameters of the sensor are analyzed in detail.Aiming at the real-time of velocity measurement,several fast cross-correlation algorithms arediscussed,including the rapid correlation between string-parallel algorithm,rough search and exact search and the discussion of fast fourier transform algorithm.At the same time,the algorithm of the part of peak searching of the cross correlation value is optimized to improve the search efficiency.And the correctness and verification of the algorithm are carried out.The CAV424 capacitive signal detection integrated circuit is used to detect the signal of the sensor,and the information obtained by the STM32 microprocessor is calculated by cross correlation calculation.The flow rate and flow rate of the biphasic flow are obtained,and the result is calculated by the serial port dedicated visual display.In this paper,the basic flow pattern of the fluid is summarized,and the theoretical basis of the cross-correlation function and the cross-spectral density is discussed.The accuracy and error of the cross-correlation system are discussed,and the main factors of the error are analyzed.The cross correlation algorithm is verified by MATLAB with typical simulation signals.The accuracy and real-time performance of the speed measurement device based on the fast correlation algorithm are tested,and the hardware circuit and the host computer platform are built.The innovation of this paper is as follows: Firstly,the double helix plate capacitor used in deepsea oil recovery sensor,both with a corrosive fluid can not contact with the measurement,easy to outsource in the outer wall of the pipeline,but also to ensure that the sensor has Uniform sensitivity,when the fluid flows through the sensor can produce a relatively uniform field,to a certain extent,simplifies the signal processing and calculation.Secondly,the combination of optimized fast cross correlation algorithm and double helix plate capacitor,is the real-time measurement system to achieve non-contact measurement,and has a real-time measurement.