Differential acoustical resonance spectroscopy: an experimental method for estimating acoustic attenuation of porous media

Abstract

A new acoustic method of estimating attenuation in rocks is presented. This method, called Differential Acoustic Resonance Spectroscopy or DARS, uses the perturbation caused by a small sample of rock to the and resonant frequency of a fluid‐filled cavity resonator. The changes in the resonant frequency and quality factor are interpreted to characterize the velocity and attenuation properties of the rock sample. The frequency of DARS operation is determined by the size of the fluid‐filled cavity, not the size of the rock sample;therefore, DARS can be used to measure an acoustically small sample in the laboratory at relatively low frequencies. Moreover, the sample may be irregularly shape so long as its size is small in comparison to the cavity volume. This paper describes the DARS concept, theory of operation, and some attenuation results for small porous samples at a frequency near 1 kHz.