Navegando por Autor "MONTES VIDES, Luis Alfredo"

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Determinação das velocidades intervalares usando a teoria paraxial do raio: aproximação de segunda ordem dos tempos de trânsito
(Universidade Federal do Pará, 1998) MONTES VIDES, Luis Alfredo; SÖLLNER, Walter Franz
In this work a method was developed to solve the inverse seismic problem in models consisting of isotropic and homogeneous layers separated by smooth interfaces, which determines the interval velocities in depth and calculates the geometry of the interfaces. The traveltime is expressed by a function with parameters referred to a coordinated system fixed at the central ray, and numerically estimated at the superior surface of the model in the vicinity of the normal ray. The function is later recalculated at the anterior interface limiting the unknown layer, through a process which determines the characteristic function in depth. The characteristic function of the traveltimes evaluated at the anterior interface allows to know the interval velocity of the layer and the geometry of the posterior interface where the normal reflection takes place. The procedure is repeated recursively at deeper layers getting the complete solution without a priori knowledge but the upper determined layers. Computer’s programs expressing the algorithm of the method were developed and tested with synthetic seismic data, generated through models with structural factions very common in geological sections, obtaining the interval velocities in depth with considered acceptable errors and reconstructing the interfaces. A sensibility analysis was done in order to verify the stability of the two methods. The empirical range of applicability of hyperbolic dynamic corrections was taken for the range of applicability of the developed method.