Research and Validation of Pipe Acoustic Transmission Mechanism

During oil production an acoustic communication mode with downhole oil pipe as channel is one of feasible downhole control method. Based on a mechanism analysis, this paper presents a pipe acoustic transmission mechanism model. The model is derived to obtain a pipe dispersive equation. The simulation of phase velocity, group velocity and dispersion curves of three common oil pipes indicates that spectral distribution of longitudinal wave transmission in pipe presents a comb filter structure, and the passband/stopband distribution approximates periodicity and symmetry on spectrogram. The passband range, stopband range and amplitude value changes with length, cross area, density of oil pipe and joint. And the influence rule is given. Then the optimal frequency is suggested through simulation for downhole wireless communication tools design.