EXPERIMENTAL-STUDY OF ULTRASONIC-WAVES AT TENUATION IN POROUS ROCKS

The attenuation of an ultrasonic wave in porous rocks has been measure d by means of a spectral analysis technique in the frequency range 100 kHz-1 MHz. Experimental results, after compensation for the geometric divergence of the emitted ray beam, are presented for three types of rocks. They display two characteristics, essentially related to the na ture and the structure of the probes: the quality factor Q does not de pend on frequency (Q is Fairly constant in the whole range of explorat ion); and the attenuation remains high. Experimental data are also com pared to predictions obtained from different models, but only Stoll's composite model gives predictions in fair agreement with experiments.