On the theory of local sounding of hydraulic fractures using pulsed pressure waves

The paper considers the evolution of a pulse signal in the annular gap between a diagnostic probe and an open well surrounded by a low-permeability fractured formation. Fractures are located along the well, and the well and the fractured-porous medium are filled with the same acoustically compressible fluid. The problem is solved numerically by the fast Fourier transform. Dispersion equations are obtained that describe the propagation of damped traveling waves in the gap, taking into account fluid filtration through longitudinal fractures. Analysis was performed of the influence of the filtration characteristics of the reservoir, hydraulic fractures, and the width of the gap between the probe body and the borehole wall on the phase velocity, the attenuation coefficient, and the evolution of pulse signals.