Laboratory investigation of sound induced by gas flow in porous media

This paper is devoted to studying the parameters of acoustic signals induced by fluid flow in porous media. The setup design and technique of acoustic measurements are described in detail. Sound induced by nitrogen flow in different types of carbonate rocks and sandstones is measured and analyzed. Limestone samples generate acoustic signals within a frequency range from 2 to 30 kHz. Sound in sandstone is significantly different from that in the limestone samples and occurs in a frequency range from 1 to 5 kHz. For limestone samples, sound generation is observed at lower flow rates than for sandstone due to earlier transition to a non-Darcy flow regime. From complementary analysis of hydrodynamic parameters of experiments, it is inferred that acoustic signals in rock samples appear only when the Forchheimer number exceeds values in the range 0.3–0.4. It is demonstrated that the recorded sound is mainly produced in the relatively thin near-surface zone of rock samples.