Research on time-frequency analysis method of drill string vibration logging technology

In order to extract effective signals during rock breaking, drill string vibration logging technology was adopted, and three component accelerometer was installed behind the drill bit to collect vibration signals during rock breaking. Different time-frequency analysis methods such as short-time Fourier transform, wavelet transform and Hilbert-Huang transform are used to analyze the numerical simulation signal processing to compare the advantages and disadvantages of various analysis methods in terms of time resolution and frequency resolution. By comparing the characteristics of different time-frequency analysis methods, it is decided to use the short-time Fourier transform to analyze the actual data of a mine in Guizhou，the position of lithology change and the change of working state of drilling rig are determined according to the characteristics of time-frequency signals in different positions. The study results show:when rock breaking is compared with coal breaking, the energy below 200 Hz is more than 5 times stronger than that of coal breaking. The energy at 400 Hz and 800 Hz position of energy are more obvious, coal breaking can only see very little energy in the corresponding position, and coal breaking above 800 Hz has no energy. The drilling rig has little energy at 200 Hz and 400 Hz, and its energy value is less than 1% of that at breaking rock and coal. When the drilling rig advances and retreats horizontally, there is only the inherent low frequency of the original rig working below 10 Hz.The division of lithology and determination of drilling rig working status by drill string vibration logging technology can provide strong technical support for actual mine drilling.