Research On Downhole Flow Control And Communication Technologies Of Intelligent Completion System

As an important raw material for industrial production,oil is regarded as strategic material by all countries in the world.China's dependence rate on foreign oil is increasing year by year,so it is urgent to improve the oil and gas recovery.Due to the complex geological conditions of reservoir,it is necessary to use multi-layer well,branch well and horizontal well to realize uniform and reasonable exploitation of downhole reservoir.However,when using conventional completion technology in the production of these complex structural wells,it is difficult to realize the real-time monitoring and control of underground production,not to mention the heavy workload and high difficulty.Therefore,there's a need to develop intelligent completion system,reducing construction intensity and improving the meticulous production.China has not developed a smart completion system yet.Foreign countries has developed different intelligent completion systems applied to different types of oil wells,but those technologies are expensive and the systems are huge,still needed to be further improved.Based on the analysis of intelligent completion technology and system,a set of all-electric intelligent completion system scheme for Chinese characteristics is proposed.It is aimed at the research of downhole flow control technology and communication technology,and the corresponding hardware and software systems are developed,followed by a series of function experiments and system comprehensive tests.The main contents of this paper are as follows:Firstly,based on the composition and function analysis of the intelligent completion system,a new intelligent completion system is designed,including downhole flow control valve mechanical design,downhole control system design,power supply system design and information transmission system design,followed by the overall scheme of the all-electric intelligent completion system.Secondly,the research on the zonal flow control technology is carried out.Based on the structure of the downhole flow control system,the flow control strategy is proposed and its control algorithm based on fuzzy PID is studied.The control system model is established and the simulation of the control system is carried out in Simulink.The results show that the control system has good control performance.Then,in order to improve the reliability of signal transmission of the intelligent completion system,channel impedance and transmission attenuation are further studied.Based on the transmission model of single core logging cable,the channel attenuation model is established,and impedance matching of the communication system is carried out.Finally,the hardware of the control system is designed and developed,and the corresponding system software is developed.The flow valve control experiment and power line carrier communication experiment are carried out in laboratory.And the control and communication system integration tests are conducted.The intelligent completion system proposed in this paper has been verified experimentally,and the indoor experiments show that the whole system has good overall performances.Although the intelligent completion system designed has achieved all the functions,there are still some deficiencies in theoretical research and practical application.At the end,the summary of the paper was made and the focuses of further research were put forward.