The Research On The Downhole Multi-state Parameters Monitoring System

Today, with the rapid development of industry, the oil demand is rising and the easyextraction oil is reducing day by day. In the process of oil collection, ESP(ElectricalSubmersible Pump), becomes the irreplaceable equipment because of the advantages of thegreat vent mete and high raise order. And, it is widely used in different kinds of oil field,such as slant well, oil extraction on sea and so on. ESP usually works at high temperature,high pressure and formidable working environment underground of the deep well. Thereliability and security of ESP play a crucial role in high yield.The research and development of the underground multi-states parameters monitoringsystem with self-owned intellectual property have the important practical value to improvethe skill level of oil collection, and to ensure the high performance of ESP. In this paper,seven state parameters of submersible pump unit, including the inlet and outlet pressure,the environmental temperature, the electrical machinery’s temperature, the vibration of Xand Y direction and the leakage current, are measured and transmitted, and the wholemonitoring system block is proposed. Using power line carrier communication technologyin this paper, the underground multi-state parameters are transmitted to equipment on earththrough the three-phase oil submersible cable. At present, converter drive is the bettermode to control ESP, but the high level harmonic interference are also brought on the cableto interrupt the signals transmission. Based on low frequency power line carriercommunication technology and the corresponding communication protocol is designed, toensure the signals on the submersible cable can not be interrupted by high frequency noise.Through the analysis and research on domestic and foreign underground monitoring technology’s materials, and combination of the high temperature, high pressure andcomplex formidable environment, designing the measure electrical circuit, and thecoupling circuit to modulate the signals onto the cable, which is suitable for thecommunication protocol. On the ground, the demodulation circuit with protection, peeledoff and filter circuit are designed, to transmit the signals to processor. Determining theunderground multi-state parameters monitoring system power supply’s scheme, which thesignals and power supply are on the same channel. Finally, compared with the differentkinds of transmission plans, through the analysis of signals transmission based on theanalog current loop, high and low frequency carrier channel’s advantages. Eventually, thesignals transmission based on low frequency carrier channel is chosen because of theunique advantages.