Geoelectrical and seismic prospections in hydrogeology: Model and master curves for the evaluation of porosity and water saturation

Evaluation of Porosity and Saturation Degree by Laboratory Joint Measurements of Velocity and Resistivity: A Model Improvement

“…The experimental study of the electroseismic model was conducted by comparing values of porosity (F) and saturation degree (S w ) obtained from the model (CARRARA et al, 1994) with those previously calculated by geotechnics and assumed as standards. The latter were obtained after having established specific weight (k s ), weight/volume dry (k d ) and water content (w).…”

“…The electroseismic model of CARRARA et al (1994) gives the scheme of a rocky mass as a polycomponent medium made up of matrix, clay, water and air; the percentages of which constrain the porosity and the saturation degree and thus the velocity and the resistivity. This medium may be considered as a combination of parallel elements in terms of electrical resistivity, and serial elements in terms of elastic wave propagation velocity.…”

“…A relationship between resistivity and velocity was derived which permits the calculation of F and S w for each couple of values of z and V P (Appendix A). A first experimental test of the electroseismic model (CARRARA et al, 1994) could not be considered exhaustive for the problem in question. Therefore, a further study was programmed which, highlighted the validity and the limitations of the model, allowed a correction of the formulation, rendering it more suitable for practical applications.…”

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This paper illustrates the laboratory procedures and experiments carried out on samples with different lithologies and reconstructed samples in order to test and implement an electroseismic model (CARRARA et al, 1994) which allows the evaluation of porosity and the saturation degree of rocks. The testing was conducted by comparing porosity (F) and saturation degree (S w ) values, obtained from measured resistivity (z) and elastic wave velocity (V P ) by means of appropriate formulations, with the values of F and S w previously calculated by geotechnics and employed as standards.

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Evaluation of porosity and degree of saturation from seismic and electrical data

“…An electro-seismic model is a system of equations that links some hydrological and mechanical parameters of soil to geophysical parameters. For example, Carrara et al (1994) proposed a model based on the scheme of a rock mass as a polycomponent medium made up of matrix, clay, water and air. Their model was based on the time-average model proposed by Wyllie et al (1956) for seismic velocity and the model of parallel resistors proposed by Patnode & Wyllie (1950) for electrical resistivity.…”