Design and Experiment of Turbine Generator Applied to Gas Drilling

With the maturity of electromagnetic wave transmission measurement while drilling technology, em wave transmission tools have been applied to the measurement and control of gas drilling well trajectory. However, due to the dry shaft wall and poor conductivity of gas drilling, especially the electromagnetic wave signal attenuates obviously in the formation, the transmission distance is affected. Enhance the emission power of electromagnetic waves could decrease the impact of signal attenuation, At present, measurement while drilling system is powered by battery in gas drilling, but the output of battery power is limited. The downhole generator technology can effectively improve the emission power of the signal source, However, due to the low gas density and compressibility, the conventional turbine components cannot drive the rotor shaft of the downhole generator as normal. This paper use the classical formula to determine the performance parameters of the gas drilling downhole generator body, Based on the study of the velocity vector triangle of the turbine blade in the two-dimensional flow field, analyzed the relationship between turbine output speed and torque in gas drilling conditions, then proposed to increase the torsional characteristics of turbine output by using planetary gear mechanism, through the above research, the air-drive turbine suitable for gas drilling is developed. CFD software is used to simulate the full three-dimensional flow field of the turbine, and the simulation results meet the design expectations. The test verifies that the steady-state output of the gas-driven turbine generator can reach 500 W, which meets the high-power emission requirements of electromagnetic wave transmission in gas drilling.