Research On Monitoring Technology Of Operating Condition Of Electrical Submersible Pump

Electrical Submersible Pump(ESP),as an important artificial lift equipment for oil,plays an irreplaceable role in secondary or tertiary oil recovery.Especially with the decreasing reserves of easy extraction oil day by day,there is a higher reliability demand with ESP applications because of more and more complicated well condition.ESP,as an rodless pump which works underground of deeper than l km,its reliability and running performance are affected by the high temperature,high pressure and severe vibration of well environment,so it has significant and practical value on researching ESP state monitoring to improve the reliability of ESP and to extend ESP service life.This paper,which is based on Daqing oilfield project,researched on ESP produced by Daqing Oilfield Powerlift Pump Industry Co.,Ltd,studies on the key technology and its Engineering Realization of ESP running monitoring.Some key technologies with comprehensively study and oilfield experiment have been taken while ESP is running,such as precise measurement on real signals of temperature,pressure,vibration and leakage current,long distance signal transmission,signal demodulation on surface,the displacement online identification of ESP,running status analysis and faults pre-diagnosis.Reference to the current developing of ESP multi sensor downhole tool(MDT)and special working condition,the study on how to transmit signal has been taken based on low frequency digital coding technique,and others methods like downhole status signals extraction and process and power supply for downhole MDT are also discussed.When ESP is driven by VSD,the interfere from unbalance voltage and high order harmonics to downhole signal transmission is measured and analyzed,and based on above research,corresponding hardware filter and software filtering algorithm are studied and the accuracy of parameter's measurement is improved.Displacement of the ESP is the key parameter to ESP working status.Considering the limitation of well fluid and the structure of the flow gauge,it's unrealized to measure the displacement of the oil well directly.Based on relationship between displacement and downhole pressure,motor running amp and frequency,combined characteristic curve of ESP,the real displacement are identified by applying piecewise linear approximation algorithm.For those ESP wells with high viscosity fluid and gas,the characteristic curve was calibrated before displacement identification.According to the requirements of the project and engineering demand,by combining current curve comparison and fault characteristic diagnosis,ESP running status is analyzed based on monitoring data and identified displacement.After that,aiming to three different optimizations on ESP running,corresponding parameter's adjustment methods are given.The oilfield testing has shown that these methods have useful value for extending ESP service life and improving its whole efficiency.