Development Of Ball-throwing Type Intelligent Control Separate Switch In Downhole

Separate layer production is an effective way to reduce the interference between the oil layers and improve oil recovery,the key technology is how to control the switching of the underground multi-objective reservoir valve effectively.According to the defect of current mainstream of hydraulic,cable and fixed program downhole intelligent switches,we design a ball-throwing type downhole intelligent switch control system based on RFID(Radio Frequency Identification)radio frequency technology with the requirements of actual process and monitoring and controlling.The main work includes:After the special environment with high temperature,high pressure,highly corrosive,small space and multi-interference in downhole have been considered,a variety of short-range wireless communication modes have been analyzed,the system has been designed as following.Two balls needs to be thrown into the oil tube during the entire process.Firstly,a wake ball has been thrown to wake up the downhole controller,and then a signal ball should been thrown with the command of opening or closing the target reservoir development valve to control the downhole target layer switch valve.The hardware of this system,including instructions reader and writer aboveground,small ball and controller downhole,has been designed and fabricated.Non-ferromagnetic materials tungsten steel tubing has been used as test tubing,winding and installation method of downhole antenna has been determined after modeling and simulation of antenna.For increasing the effective communication distance between downhole controller and the ball,class B resonance power amplifier has been adopted to magnify the downhole electromagnetic energy.For the requirements of low power in downhole,diode envelope detector has been used to demodulate the receive data in downhole.For saving the overall power consumption caused by downhole controller,low power mode converting to working mode has been adopted.The software of this system,including instructions reader and writer aboveground,controller downhole and PC software,has been designed and implemented.Considering the passive components and the limitation of signal power in the balls,Manchester code has been adopted in signal emission and pulse width code has been used in signal reception for improving the anti-interference performance and decreasing the error rate.Coding and decoding have been realized by software,the volume of downhole circuit has been minished and the allomeric function has not been influenced.Speed has been tested in experimental prototype,the maximum falling speed of the ball with normal communication has been determined,this speed can be used as a reference in subsequent weighting.This machine has been simulation tested underwater,the results show that,communication between the ball and downhole controller runs well,and the downhole switch valve has been controlled effectively.The overall design can satisfy the system request fully.