| With the development of drilling technology,and the technical process requirements for deep wells,ultra-deep wells,horizontal wells,and directional wells,traditional drilling methods could not meet the technical requirements of drilling.As rotary steerable technology has become a necessary means to enhance the drilling process,this technology has been mastered by developed countries who has monopolized the technology of other countries.Therefore,the localization of rotary steerable technology is an essential means to improve China's drilling technology.It is of great significance to carry out rotary steerable technology research.Therefore,this article combines the major national science and technology projects named 2011ZX05021.-005 "Rotation guidance and measurement and recording while drilling,and acid gas layer testing technology and equipment",and proposes a control system for brushless motor used in the positioning assembly of the rotary guide system actuator to improve the rotary guide tool in Work stability in deep and ultra-deep wells and reduce borehole trajectory errors.This article starts with the establishment of the motor model,and builds the working state model of the motor according to the downhole environment,then completes the design of the motor control model which realizes the motor control circuit.It systematically tests the designed motor control circuit,and uses the drive circuit to perform an overall test of the entire positioning assembly hydraulic system,which meets the design requirements.At the same time,it used the test system to complete the local testing of the motor and relief valve,and achieved satisfactory results.The combination of sensors in the rotary steerable system is optimized based on it,and the borehole trajectory error is reduced through experimental verification.The main results of the thesis are as follows:The position of the motor is detected by the back electromotive force,which solves the problem that the motor has a small back electromotive force at the start of rotation and cannot directly control the motor through the back electromotive force.A delay time-adjustment scheme is designed to reduce the motor speed jitter which is generated when the speed is adjusted.A fault detection program is designed so that two fault processing methods are adopted for the motor when the motor has a speed fault.And a real-time detection system for reducing the position error generated in the control motor is designed.The sensorless brushless motor was successfully applied in the positioning assembly.Through the study of different rotary steer-measurement tools' measurement error,and designing different measurement tools to be used to calculate the error under the combination of different tools,a kind of combination of measurement tools for minimum error in drilling a horizontal well is obtained through the actual borehole trajectory for simulation and comparison.Finally,the entire experimental platform was set up to carry out systematic experiments,which can use the algorithm to correct the changes in the motor parameters,ensure the stability of the output power of the motor in the positioning assembly in the downhole,and ensure the accurate control of the hydraulic oil pump speed,which increase the average efficiency by 5 percentage points.And at the same time,the pressure output error of the three positioning assemblies was reduced by 3%,and the borehole trajectory was accurately controlled. |
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