Research On Control Strategy Of Electrical Submersible Pump

With the rapid development of the world economy, the demand for oil is constantlyincreasing. Our country is very rich in oil, but with some major oil fields moving into themiddle of exploitation stage or later, the development of heavy oil become the main focusof national and international experts attention. The viscosity of heavy oil is sensitive totemperature, in order to improve recovery factor, the method of steam injection are usuallyused to reduce the viscosity of crude oil. With the application of thermal recovery, thetemperature of the crude oil is generally rises. The operating state of electrical submersiblepump will be seriously affected, meanwhile, the safe operation of electrical submersiblepump system is threatened. Therefore, higher requirements and standards of reasonablecontrol to electrical submersible pump have been proposed.Based on the introduction of heavy oil recovery, this paper combined thecharacteristics of the steam assisted gravity drainage technology, especially for theproblem high temperature steam making the temperature of crude oil higher. In order toensure electrical submersible pump continuous and efficient work, it has importantsignificance in improving the system efficiency and energy saving by controlling therunning state of electrical submersible pump reasonably according to the change ofdown-hole parameters. This article mainly includes the following content:Firstly, the theoretical analysis and research were carried aiming at the phenomenonof liquid vaporization caused by the environment of high temperature and pressure. Thenaccording to the critical conditions of evapotranspiration liquid water occurs, fuzzy expertcontrol system is established for oil production environment of high pressure andtemperature from210℃to240℃, and the advantages of fuzzy technologywere used tocope with the effects of incomplete system data, the whole system reasoning experimentwas carried out to achieve effective control to the working state of the electricalsubmersible pump through the changes of the down-hole temperature and pressure. Secondly, according to the theory of production-extraction balancing, themathematical model of motor speed and dynamic liquid level is established throughtheoretical derivation. And referring to critical condition of phase change of liquid water inhigh temperature and pressure environment, speed mathematical model under the conditionof high temperature is also established according to the actual operation of the mineenvironment, at the same time, the best running status of the motor speed with the dynamicliquid level changes were ensured to maintain it in an efficient and stable workingcondition.Finally, according to the mathematical model of motor speed dynamic and liquid levelin high temperature above, using MATLAB/SIMULINK software, the dynamic fluid levelcontrol simulation model was established. The simulation research work was carried andthe relationship between fluid level and speed under different temperature has been studied.The simulation results show that at the same liquid level, the motor speed decreases withtemperature increasing. At the same time the simulation circuit of asynchronous motorvector control system was built for simulation experiment of asynchronous motor stepchange situation in the rotational speed. The simulation results show that the system ownsgood speed regulation to meet the needs of engineering practice.