| Modern oil and gas drilling system requires to transfer the data from well to ground in high accuracy and high speed with limited energy. The oscillating mud pulser is one of core MWD/LWD components. The oscillating mud pulser is, mainly, made of stator and rotator. Relative motion between stator and rotator leads to complex transformation of drilling fluid. Drilling fluid mainly consists of water and fine sand. The drilling fluid flows fast around the stator and rotator, and the turbulence effect is clear. As a result, hydraulic characteristic on rotor is complex, which is not easy to fully understand.Firstly, this thesis introduces the current situation of LWD/MWD and the development trends of multiphase theory. Then, this research points out that it is necessary to take the effect of multiphase into the research of oscillating mud pulser, and essential equations of fluid dynamics applied in the area of oscillating mud pulser is also introduced. Secondly, the theory of the steady-state hydraulic torque had been used to analyze the hydraulic torque on the rotor in the present study. Finally, hydraulic torque was analyzed by a CFD software, and comparisons are made for numerical results between the multiphase flow and the water only. The effect of multiphase to the oscillating mud pulser is also discussed. The numerical results shows that the multiphase effect is a must to be taken into consideration. |
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