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. The manufacture of synthetic rock samples has a great importance in the study of the elastic properties of the rocks based on the variation of heterogeneities. For this work we constructed synthetic sandstones with different number of heterogeneities in the samples. We analyzed all samples from ultrasonic point of view (in dry and saturated condition). In total, twelve heterogeneous samples and an isotropic sample for reference were constructed. The heterogeneous samples were divided in three groups (A, B and C): group A with heterogeneities of 3.75-4.25 mm in diameter, group B with heterogeneities of 5-6 mm in diameter and group C with heterogeneities of 6.5-7.5 mm in diameter. From the first arrival picking on P- and S-waveforms, we calculated VP and VS velocities. We also compared the experimental velocities with ones predicted by the theoretical models of modified Maxwell-Garnett and the Kuster-ToksA¶z models. The theoretical predictions were made for the P and S velocities for the dry and saturated cases. In general, we noted that the best fit between the theoretical and experimental values occurred for the prediction of the modified Maxwell-Garnett model. Keywords: ultrasonic waves, effective model theories, synthetic samples, heterogeneous media. RESUMO. A fabricacao de amostras de rochas sinteticas tem uma grande importância no estudo das propriedades elasticas das rochas com base na variacao de heterogeneidades. Para este trabalho construimos arenitos sinteticos com diferentes numeros de heterogeneidades nas amostras. Analisamos todas as amostras do ponto de vista ultrassonico (em condicao seca e saturada). No total, foram construidas doze amostras heterogeneas e uma amostra isotropica para referencia. As amostras heterogeneas foram divididas em tres grupos (A, B e C): grupo A com heterogeneidades de 3,75 a 4,25 mm de diâmetro, grupo B com heterogeneidades de 5 a 6 mm de diâmetro e grupo C com heterogeneidades de 6,5 a 7,5 mm de diâmetro. A partir das escolhas de primeira chegada, tomando as formas de onda P e S, calculamos as velocidades VP e VS. Tambem comparamos as velocidades experimentais com as previstas pelos modelos teoricos dos modelos de Maxwell-Garnett e Kuster-ToksA¶z modificados. As previsoes teoricas foram feitas para as velocidades P e S para os casos seco e saturado. Em geral, notamos que o melhor ajuste entre os valores teoricos e experimentais ocorreu para a predicao do modelo de Maxwell-Garnett modificado. Palavras-chave: ondas ultrassonicas, teorias de modelos efetivos, amostras sinteticas, meios heterogeneos.

THEORETICAL AND EXPERIMENTAL ANALYSIS OF ULTRASONIC WAVES PROPAGATION ON SYNTHETIC SANDSTONES WITH SPHERICAL HETEROGENEITIES