Research On The Down-hole Data Sampling And Transmission Method

With the development of oil exploration technique, oil explored methods have been developed from exploring with screw pumping unit to that with ESP(Electrical Submersible Pump), which plays an increasingly important role in oil exploration. Detecting for working state of ESP has important significance of research and great value in use to the safe operation of equipment and failure prediction.In this paper, research of the down-hole data sampling and transmission methed of ESP is conducted for ESP driven by inverter to monitor seven parameters of the submersible pump's working condition:the inlet pressure, the outlet pressure, the environment temperature, the electrical machinery's temperature, the vibration of X direction, the vibration of Y direction and the leakage current.In the working process of submersible pump unit, much higher harmonic is produced by inverter, resulting in that the data channel of ESP's multi-parameter monitoring system is full of high-frequency noise. That affects data transmission accuracy. In order to improve data transmission accuracy, this paper develops system data communication protocols according to standard serial data transfer protocol.Underground first instrumentation works at high temperature, high noise and other harsh circumstances, which affects the data acquisition accuracy of the data acquisition module. In order to reduce the effect to underground first instrument from the underground working environment, method based on the least squares is designed for sensor calibration to calibrate each sensor.Since the data signals of ground second instrumentation contains high frequency noise, in order to improve the accuracy of the data demodulation, the signal correction circuit are improved to filter and correct the data signal, and the demodulated data is fixed according to the data communication protocol of system. In order to improve software reliability, the control circuit of ground second instrumentation is designed based on embedded systemμC/OS-Ⅱ. The system with ATmegal28 as its core controller, MGLS240128 liquid crystal as its display terminal, and PS/2 keyboard as its data input device, are real-time controlled based on task priority. According to the system requirements for mass storage of data, this paper takes SD card as the storage medium, and designs storage modules based on the FAT16 file system specification.Finally, hardware reliability improves by screening components and circuit boards' aging treatment of underground first instrumentation. The system data transmission accuracy is improved through the calibration to data communication protocol of the system and the design of the reliability and accuracy of data acquisition modules. Through the system sealing experiment, system on-line experiment, system temperature experiment, system vibration experiment and system field experiment, it is proofed that the system can work at high temperature, high pressure, large amount of vibration, data channel full of high harmonics and other harsh environments.