Experimental Study of Statistical Characteristics of the High-Frequency Vibrations of a Drill-String Bottom

We present the results of direct measurement of vibrations of the drill-string bottom structures in the drilling process. Special attention during the measurements is paid to the high-frequency part of the vibration spectrum. The vibrations were recorded using a specially manufactured downhole noise recorder with an integrated three-component accelerometer and the temperature and externalpressure sensors. This recorder was adapted for embedding directly into the drill string in the bottomhole assembly area. Vibration signals were recorded in a frequency interval of up to 25 kHz. The full-scale measurements were performed for all possible borehole operations carried out for both controlled (horizontal) and vertical drilling. This work presents the distribution functions and power spectral densities of vibration noise for various drilling operations and conditions.