A perturbation method for elastic-isotropic inversion--a proposal

Carlos A. Cunha Filho

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ABSTRACT

Several methods for elastic inversion have been applied in recent years, based on the optimization of either the fitting between the predicted and recorded data, or the fitting between the model-predicted and data-retrieved reflectivity series. In both cases, the model is usually described by a stack of layers that controls the kinematics and the dynamics of the physical process. I propose a method in which geometrical and physical effects are decoupled, so that the part of the model responsible for the dynamics can be modified without introducing any change on the kinematically-related part of the model. The model is characterized by a background medium, with smoothly-varying elastic properties, and an arbitrary number of perturbation layers. Each perturbation layer is responsible for the introduction of two reflections, whose amplitudes depend only on the contrast between the properties of the layer and the local properties of the background model. In addition to the kinematics-dynamics uncoupling, the number of unknown parameters necessary to describe the two reflections of a layer (top and bottom) is reduced to less than a half of the number required by usual model-description methods.