Research on Downhole Wireless Transmission Technology

The efficient transmission of down hole information without cable is an urgent problem to solve over the years, the key technology is to design the underground excitation source under the high temperature and pressure, narrow and small space, complex electromagnetic environment. The core idea is to apply power inverter technology to underground transmission system, producing down-hole excitation signal, tubing and casing used as a transmission channel, transfer the signal to the ground without cables This article carried on the detailed analysis to the sinusoidal pulse width modulation wave (SPWM), choosing high-power switch MOSFET constitute a single-phase bridge PWM inverter circuit, PWM wave produced by micro controller module CPP control switches the complementary conduction, to generate high-power sine wave pulse width modulation SPWM, using LC low-pass to filter out the harmonic components, obtain the fundamental component, that is high-powere sine signal source. Underground power supply of the entire system is required not the limited battery, but the generator with the unlimited mechanical energy converting to electricity power, so to achieve the real-time communications from down hole to surface. It enhances not only the driving capability of underground launch system, but also the data transmission capability. Laboratory and field tests prove that the system performance has meet the design requirements.