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. Seismic methods study the propagation of elastic wave fields inside the Earth, with the goal to provide subsurface images. In this work, the determination of the time interval velocity distribution is the main information provided. Several synthetic models were used, where one is based in a real situation, a dip section from the pre-salt region, central part of the Santos Basin, Brazil. Themethods used to determine interval velocities were based on the Dix transform, singular value decomposition (SVD) and minimum relative entropy (MRE). Dix transform showed excellent results when used in simple geological models, and was coincident to the other two methods. With the addition of a priori information, the SVD and MRE showed to be good methods for the determination of the interval velocities. When comparing SVD and MRE methods the latter showed the best results. When the a priori information is constant, the SVD and MRE methods give the same velocity estimate given from the direct application of the Dix transform. Keywords: inversion of interval velocities, singular value decomposition, minimum relative entropy, pre-salt. RESUMO . Os metodos sismicos utilizam o campo de propagacao de ondas elasticas no interior da Terra, com o objetivo de fornecer imagens da subsuperficie. Neste trabalho, a determinacao do campo de velocidades intervalares e a principal informacao a ser fornecida. Foram utilizados modelos sinteticos, sendo um deles baseado em uma situacao real, no caso uma sessao dip , na regiao do pre-sal, parte central da Bacia de Santos. Os metodos usados para determinar as velocidades intervalares foram a transformada de Dix, a decomposicao por valores singulares (SVD) e a entropia relativa minima (MRE). A transformada de Dix, quando usada em modelos geologicos mais simples apresentou excelentes resultados coincidente aos outros dois metodos. Com a adicao de estimativas a priori , o SVD e o MRE se mostraram como bons metodos para a determinacao das velocidades intervalares, sendo que o MRE apresentou os melhores resultados. Quando a informacao a priori e constante, os metodos do SVD e MRE fornecem a mesma estimativa de velocidade que e obtida pela transformada de Dix. Palavras-chave: inversao de velocidades intervalares, decomposicao por valores singulares, entropia relativa minima, pre-sal.

INVERSION OF INTERVAL VELOCITIES: APPLICATION TO A GEOLOGICAL MODEL FROM A PRE-SALT AREA