Study On The Modeling And The Hydromechanics Of The Fluid In The Auto Anti-Deviation Drilling System

When the automatic anti-deviation drilling system is in operation ,a relative rotate speed is needed between the steerable sleeve and the drill string to produce essential anti-deviation powers.The steerable sleeve rotates as a result of the friction torque exerted by the bearing connecting the sleeve and the drill string,while the backtracking muds pass through the sleeve and produce a reverse torque preventing the sleeve from rotating,which is a key factor to ensure a relative rotate speed between the sleeve and the drill string.To know more about the characteristics of the down-hole muds in the automatic anti-deviation drilling system and explore the value of the reverse torque and its factors,we need to study the flow field of the down-hole muds both theoretically and with simulation.At first,the flow field of the down-hole muds was analyzed and caculated with hydrodynamic theories,providing the essential foundation for the subsequent simulation.Then the CFD software Fluent was used to model the flow field of the down-hole muds,and explore the flow characteristics.The theoretical analysis,the simulation results and the experimental figures were studied by contrast and the characteristics of the down-hole muds were found out.The simulation results indicated that the value of the reverse torque depends on several factors such as the mud flux, the sleeve rotate speed and so on ,and as long as the rotate speed of the drill string exceeds the critical rotate speed , the reverse torque by the muds to the sleeve is sufficient to produce a relative rotate speed between the sleeve and the drill string.The dynamic analysis of the flow field of the down-hole muds in the automatic anti-deviation drilling system is very important to the regular operation of the automatic anti-deviation drilling tools.The characteristics of the down-hole muds in the automatic anti-deviation drilling system were studied both theoretically and with simulation,the operation condition of the steerable sleeve was explored and analyzed,and a solution to preventing the steerable sleeve and the drill string rotating with identical speed was advanced.