Attenuation model and law of high-frequency drilling fluid pressure wave

The technology of transmitting high-frequency drilling fluid pressure wave information with high transmission rate. It is also one of the key technologies to achieve the automated and intelligent drilling. However, the field application of this technology is hindered by the substantial attenuation experienced by high-frequency drilling fluid pressure waves during the transmission process. Thus, exploring the attenuation characteristics of these waves is crucial for the development of high-speed transmission technology. Herein, it is assumed that the drilling fluid pressure is equivalent on the same section of drill string, and the flow rate of drilling fluid is radially distributed. On this basis, an attenuation model for high-frequency drilling fluid pressure waves was established based on the two-dimensional axisymmetric transient flow theory with the small signal analysis method, for which the applicable conditions were given. In the model, the impact of pressure wave signal parameters, drilling string dimensions, and drilling fluid properties were taken into account, and the accuracy of the model was verified through ground experiments. In addition, the effects of the frequency and transmission distance of drilling fluid pressure wave, the density and viscosity of drilling fluid, and the inner diameter of drill string on the attenuation of high-frequency pressure waves were analyzed employing this model. The analysis results demonstrate that the amplitude attenuation of high-frequency drilling fluid pressure waves increases exponentially with higher pressure wave frequencies, longer transmission distances, and greater drilling fluid viscosity. Moreover, the amplitude attenuation is primarily influenced by the wave frequency, gradually decreasing as the density of drilling fluid and the inner diameter of drill string increase. Generally, this study could offer theoretical guidance for developing the transmission technology of high-frequency drilling fluid pressure wave information.