Navegando por Autor "RÉGIS, Cícero Roberto Teixeira"

Agora exibindo 1 - 2 de 2

Acesso aberto (Open Access)
Inversão vinculada de dados de EMAP e MT-1D anisotrópico
(Universidade Federal do Pará, 1999-11-26) RÉGIS, Cícero Roberto Teixeira; RIJO, Luiz; http://lattes.cnpq.br/3148365912720676
We present a technique to invert magnetotelluric data. Two kinds of MT data are treated: data generated by anisotropic one-dimensional models and two-dimensional data from EMAP (ElectroMagnetic Array Profiling) surveys. In both cases we perform the inversions using approximate equality constraints to stabilize the solutions. We show the advantages and the limitations of those constraints in the inversion process. Even when the inversion is constrained, it can still be unstable. To invert the two-dimensional EMAP data we present a process that consists of three steps: 1 – The interpretation model and the initial guess for each case are derived from the filtered apparent resistivity sections which are the result of the filtering process of the EMAP method; 2 – One layer formed by small outcropping bodies (termed static shift layer) is added to the interpretation model in order to resolve the sources of static distortions that contaminate the data; 3 – The inversion is constrained by approximate equality constraints. The first two steps enable us to extract the largest possible amount of information from the data, while the use of the approximate equality constraints allow us to incorporate a priori information which has true physical or geological meaning. With these steps we obtain solutions that are stable and meaningful. We study the method in two-dimensional models as well as in real data from an EMAP line surveyed at the Paraná Basin.
Acesso aberto (Open Access)
Modelagem e filtragem de distorções estáticas em levantamentos de dipolos contínuos
(Universidade Federal do Pará, 1994-02-02) RÉGIS, Cícero Roberto Teixeira; RIJO, Luiz; http://lattes.cnpq.br/3148365912720676
Static distortions are a serius problem to the magnetotelluric method and many atempts to eliminate or to minimize them in the MT data have been tried with more or less success. This work is an overview on a new technique that deals with this problem, the EMAP method, witch is a modification of the traditional MT method in witch the measures of the electric field are made in a continuous line of dipoles equally spaced, and the data so obtained are filtered with a spatial low-pass, frequency dependent digital filter. This work is composed of two main parts, the numerical simulation of electric field data distorted by the static shift and the aplication of the spatial low-pass filter to minimize the static shift. In the first part, we use the finite elements method to simulate the response of the electric dipole witch actually makes the electric field measurements; in the second part, we aply the Hanning window as the spatial filter to treat the data.