Differential Acoustic Resonance Spectroscopy (DARS) Measurements

The objective of current research is to discuss the experimental relation between permeability and compressibility of eight natural and artificial porous samples estimated by two distinct laboratory set-ups. The first method to calculate compressibility is the conventional ultrasonic measurement (~ 1 MHz) of the dry rock velocities. The second is the so-called Differential Acoustic Resonance Spectroscopy (DARS) set-up (~ 1 kHz), which relies on the shift in resonance frequency between an empty and a sample-loaded fluid-filled cylindrical resonator. We conclude that for the five reference solids and three low-permeable samples the compressibility estimated by both methods are comparable. However, for one medium- and four high-permeable samples the compressibility estimated by both methods differs. Apparently, the compressibility measured by the DARS-method is related to the permeability of the sample.