Research on Detection Method of MWD Signal Based on Duffing Chaotic Oscillator

Amidst the course of drilling, the measurement while drilling (MWD) signal will be mixed with a large number of noise signals. These noises are mainly caused by various mechanical vibrations in the downhole. The useful signal in the MWD signal is very weak and can be easily overwhelmed by noise, resulting in a significantly low signal-to-noise ratio (SNR). In order to detect MWD signals more efficiently and accurately, the expression (-x
³
+x
⁵
) is used as the nonlinear restoring force of Duffing oscillator, and this study proposes an effective detection method based on the Duffing chaos effect. Firstly, a variable scale method is used to address the issue of the limited detection frequency of the Duffing system and the difficulty in determining the critical amplitude. Secondly, alter the initial phase of the built-in signal of the system, and the array Duffing oscillator system which can realize all-phase detection is obtained. Finally, a detection statistic based on likelihood-Halmiton system is constructed, and the steps of signal detection method based on this statistic are designed.