Experimental Analysis of Acoustic Signal Detection Using Extensional Stress Wave Along the Periodic Simulated Drillstring

Drillstring acoustic telemetry is an alternative wireless transmission method to retrieve down hole data. Based on the analysis of wave modes in drill string, the longitudinal wave is determined as the transmission medium. The experimental system is established by using simulated drill string according to the analogous principles. The excitation experiments on the effects of carrier frequencies at different receiving modes, receiver positions, transmission pulse characteristics on acoustic transmission behaviors are performed in the laboratory. Then, the data transmission is tested by applying the pulse signal excitation to the length-limited simulated drill string. The results demonstrate the transmission performance under the conditions of excitation power of 1 W, transmission rate of 77 bit/s and 6.2-meter simulated drill string via low-frequency extensional waves.