| Rotary steering drilling technology plays an increasingly important role in the development of directional,horizontal and cluster wells.Compared with sliding steering drilling technology,it has the advantages of fast drilling speed,small friction,smooth borehole trajectory and precise closed-loop control.However,its main technology is monopolized by foreign oil companies,and there is a big gap between domestic research and foreign mature technology.In addition,the combination of rotary steering technology and slim hole drilling technology is seldom studied in China.Therefore,it is of great significance to strengthen the research of rotary steering technology for breaking through the blockade of foreign technology and strengthening the development of oil and gas fields in China.The advantages and disadvantages of various rotary steering drilling tools are compared and analyzed through literature research at home and abroad.On this basis,a design scheme of small size rotary steering actuator is proposed.Compared with conventional rotary steering drilling tools,this steering actuator innovatively uses magnetic drive device as hydraulic power source,which has the advantages of wide borehole adaptability,large deflection rates and high temperature resistance.Considering the characteristics of the design scheme and the design concept of electromechanical-hydraulic integration,the design calculation and analysis of the steering actuator are carried out through theoretical research and software simulation.According to the design scheme,the structure of the steering actuator is designed,which is mainly composed of the main skeleton,bearing and seal combination,dynamic and static hydraulic connection sleeve and hydraulic push module.The key components of the structure are analyzed by finite element method,which verifies that the main structure can meet the strength design requirements under various working conditions.The principle of well trajectory control based on deviation vector is elaborated through literature research.The characteristics of three-wing rib push plate pushing against the borehole wall are analyzed through the synthesis and decomposition of force vector.On this basis,three schemes of three-wing rib control are simulated and compared.Finally,the 60 degree zone division control scheme is optimized.The hydraulic system of steering actuator is designed,its opening method is introduced,and the condition of keeping constant pressure is demonstrated.Through the analysis of the characteristics of hydraulic system and the simulation results of PID control,the control method of variable slope and accumulation of control variables is put forward.Simulink simulation proves that the control method has the advantages of stable response,no oscillation and overshoot.The load of the pump in the hydraulic system is calculated.The calculation and selection of the magnetic drive device are completed through finite element simulation of magnetic field and dynamic matching,and the calculation of eddy current loss in the magnetic drive device is completed according to the empirical formula,which verifies the rationality of the selection.The work done in this paper provides theoretical support for the design and production of practical rotary steering drilling tools. |
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