Research On Wireless Communication And Control System Of Downhole Tractor In Large Extended Reach Horizontal Well

Compared with ordinary wells,extended-reach horizontal wells have higher oil and gas recovery rate and greater comprehensive income,but there are also common problems such as pipe string running,difficult transportation of downhole operating instruments,and low ROP.The downhole tractor can effectively solve the problem that most of the underground operation equipment or facilities cannot reach the designated position only by gravity transportation.However,the precision of the control system of the downhole tractor and the reliability of the communication system not only determine whether the fast and precise control target can be achieved,but also restrict the application of the existing tractor and the extension of the coiled tubing.Therefore,it is necessary to study the control and communication system of the downhole tractor.The overall scheme of the control and communication system of the downhole tractor is first designed,and the motion mechanism of the downhole tractor is deeply studied based on the output model of the telescopic cylinder.Model.Based on the mathematical model of the downhole tractor,PID,fuzzy PID and fuzzy neural network PID controllers were established to control the downhole tractor by using MATLAB/Simulink.The simulation results show that the fuzzy neural network PID controller has better static and dynamic response capabilities.,Compared with the fuzzy PID controller,the rise time is reduced by 0.7s,the adjustment time is reduced by 0.6s,the peak value is 8k Pa,the overshoot is 0k Pa,the parameter adjustment overshoot is reduced by 60%,and the adjustment time is reduced by 30%.Based on the non-return-to-zero coding and negative pulse downlink mode,the coding scheme of the communication system is designed,and the influence of different riser parameters,different working fluid densities and different working fluid flow rates on the pressure fluctuation proportional coefficient of the downhole tractor system is investigated by using CFX.The analysis results show that the maximum pressure fluctuation proportional coefficient is 0.85 when the 114.3mm riser,the flow rate is 35L/s,and the working fluid density is 1.0 g/cm3;The minimum coefficient is 0.60.The research results show that: for the downhole tractor,the fuzzy neural network PID controller has better dynamic and static performance,higher stability,stronger parameter convergence ability,and higher advantages in regulating speed and error control;work The proportional coefficient of hydraulic pulse pressure fluctuation increases with the increase of the outer diameter of the standpipe,increases with the increase of the working fluid flow rate,and increases with the decrease of the working fluid density.Under the same pipe diameter,the flow rate to the working fluid pressure fluctuation ratio increases coefficients have the greatest impact.The research in this paper can be used as a reference for the development of downhole tractors and similar downhole instruments,as well as for the research on the communication system of downhole devices.