Ground measurement of noise characteristics in drill string during drilling

Using the drill string in the wellbore as the information transmission channel and acoustic wave as the carrier of information transmission to realize the acoustic transmission of information in the well is an important means to realize the high-speed and accurate transmission of downhole information. However, the existence of noise in the drill string during the drilling process seriously affects the transmission rate and transmission accuracy of acoustic wave. In order to explore the characteristics of drilling noise in the drill string, the drilling noise under six different working conditions was measured on site. The results show that the frequency and intensity of drilling noise change with the change of drilling conditions and drilling parameters; During directional drilling, when drilling in normal formation, the noise frequency is mainly concentrated at 1000 Hz, when drilling in hard formation, the WOB increases, and the noise frequency will be concentrated at 6000 ∼ 8000 Hz; When combined drilling, the average intensity of low-frequency drilling noise can reach at 50 dB, while when the drilling is stopped and the pump is stopped, the intensity of low-frequency drilling noise is only 20 dB; The drilling noise is mainly concentrated in the low-frequency band of about 2000 Hz, and the strongest noise is concentrated in 800 ∼ 1200 Hz; Calculate and compare the noise intensity, select the condition of stopping drilling and pump as the best transmission condition, analyze and compare the noise frequency, and select 400 ∼ 600 Hz as the best acoustic carrier transmission frequency.