High Rate Mud Pulse Telemetry System Design

In this paper, on the basis of extensive research, combined with the existing drilling technology development, along with varieties of new measuring instruments, the successful development and the applications of underground MWD parameter increases, so we needs to transfer rate higher continuous wave signal transmission mode urgently. Aiming at the domestic mud pulse transmission technology in data transmission speed is slow, low reliability, noise processing method is not perfect, and the small amplitude signal in strong noise can’t accurate identification problem. Using CFD numerical analysis method to calculate the basic knowledge of mechanics and fluid, summed up the residual error convergence criteria and control method. Based on this topic design model, meshing, for example, model assumption, simplified analysis model related parameters setting, including boundary conditions of the mouth, export conditions, component parameter setting, etc. Then designed the structure of rotor and stator in the working mechanism of mud pulse generator, and projected the Manchester encoding mud pulse signal data information coding, then we will conclude the mud pulse power driven system; In the last use UG software to build entity model and flow model of mud pulse generator, by means of CFD software, to simulating calculate the different structure parameters and drilling parameters of mud pulse generating mechanism of flow field, in this way we can study these factors on the rotor of the hydraulic characteristics and the influence of the pulse strength, in the last,we can optimize the structure design. Conclusions are as follows: In order to easy realize the coding technology, cost savings, we combine with the actual working condition of the drilling and well logging, in the mud pulse pulsing institutions rotor motor drive system, We select the motor is a brushless dc motor. In order to guarantee the normal work of the pulse, the rotor of the maximum torque is 16.5 N?m. When the Angle of the inlet and the oil cavity alpha is less than 90 °,it can reduce the cavitation phenomenon. Especially in high speed, it can enhance the capacity of oil absorption; using the 3D drawing software UG designed variable displacement vane mud pulse system, the blade numbers is 9, the eccentricity is 2.7mm when displacement is max, blade thickness is 10.5 mm, blade width is 3 mm, radius of the stator is 35.9 mm, theoretical displacement Q = 11 l/min. When the stator moving to minimize emissions, eccentricity e 1.8 mm; When variable device works, namely the eccentricity changes, variable displacement pressure fluctuates significantly decreased after monitoring two pressure fluctuations by 1.6 bar to 0.8 bar, 3 monitoring points by 5.5 bar to 3.5 bar pressure fluctuation; Reduces the noise and vibration and extend the service life of mud pulse system.