The main objective of exploration geophysics for hydrocarbons is to provide trustworthy images the subsurface, which could indicate potential reservoirs. Exploration seismology, better known as seismics applied area most employed subsurface imaging. And within tomography was incorporated a method data inversion. In this work we use geophysical diffraction where input scattered acoustic field measured at receivers, and velocity two dimensional medium inversion output. Since an ill-posed...

A bstract The pioneering work of E. T. Jaynes in the field Bayesian/Maximum Entropy methods has been successfully explored a number disciplines. principle maximum entropy (PME) is remarkably powerful and versatile leads to results which are devoid spurious structure. Minimum relative (MRE) method all important attributes maximum‐entropy (ME) approach with advantage that prior information may be easily included. These ‘soft’ constraints play fundamental role solution underdetermined problems....

Density differences among subsurface rocks cause variations in the gravitational field of Earth, which is known as gravity anomaly. Interpretation these anomalies allows assessment probable depth and shape causative body. For several decades, data were acquired on surface, but after scientific technological advances last geopotential models developed, including observations a global scale through space satellite missions. This paper investigated Moho structure region Recôncavo-Tucano-Jatobá...

Detrended fluctuation analysis and detrended cross-correlation are used in this study to identify characterize correlated data. The objective of these two techniques is separate different fluctuations from the contributions due external trends by evaluating autocorrelation exponents, order determine if scale properties persist with size series. Two new methodologies were extended coefficients for local analysis, which we call \textit{automatic search procedure.

In this work we present several regularization techniques for the solution of geophysical ill-posed inverse problems, in case discrete data and model parameters. particular, Twomey (1963) algorithm Is applied to Invert synthetic tomographic data, both noise-free corrupted by noise. This based on a smoothness criterion where second differences parameters are minimum. The selection parameter also considered, practical trial error procedure suggested an optimal parameter, behaviour RMS misfit...

In this study, we intend to understand the climatic behavior of southern region Mozambique in face evidences climate change at global level. Time series precipitation and extreme temperatures related 1960-2018 were used. We performed characterization rainy season behavior, analysis periodicity long-term variability determination trend fluctuations temperatures. The results analyzes are current observations projections contained fifth assessment report Intergovernmental Panel on Climate...

P032 Application of GCV in Geophysical Diffraction Tomography E. Santos (CEFET/BA and Stanford University) & A. Bassrei* (Federal University Bahia) SUMMARY Since inverse problems are usually ill-posed it is necessary to use some method reduce their deficiencies. The that we choose the regularization by derivative matrices. When a first matrix used order called first. Then second when formed differences zero means identity. There an important issue which selection

We consider the conjugate gradient method for normal equations in solution of discrete ill-posed problems arising from seismic tomography. use a linear approach traveltime tomography that is characterized by an ill-conditioned system whose unknowns are slownesses each block computational domain. The algorithms considered this work regularize stopping early iteration. They do not depend on singular-value decomposition and represent attractive economic alternative large-scale problems. review...

A parallel hybrid scheme combining a particle swarm optimization (PSO) algorithm with the regularized Gauss-Newton (RGN) method is proposed as means to invert gravity data estimate depth of sedimentary basin in which density contrast varies parabolically depth. Such has potential exploit advantages both methods. In scheme, PSO was implemented construct an initial for RGN method. The former allows rapid build-up large-scale model features, whereas latter adjusts finer features. accuracy this...

ABSTRACT. Regardless of whether the cause greenhouse effect is anthropogenic, carbon dioxide (CO2) exacerbates global warming because it contributes directly to increased temperature planet. In a geologic context, CO2 can occur in conjunction with porous oil reservoirs...Keywords: seismic diffraction tomography, reservoir monitoring, Gassmann’s equation, injection RESUMO. Independentemente se causa do efeito de estufa é antropogênico, o dióxido carbono agrava aquecimento porque contribui...

We present an inversion procedure for electromagnetic scattering, based on the powerful and flexible technique called coupled-dipole method combined with optimization algorithm. This permits us to realize imaging of dielectric objects whose dimensions are comparable incident wavelength is shown be efficient corrupted data (scattered electric field). The feasibility this in a synthetic example which scattered field Gaussian noise. Two methods used invert recover refractive index medium:...

In this paper we present an inversion procedure for electromagnetic scattering, based on the coupled-dipole method (CDM) combined with algorithm making use of singular value decomposition associated a regularization factor. This permits to obtain images non-homogeneous dielectric objects whose dimensions are comparable incident wavelength. The feasibility is showed in two synthetic examples using CDM 257 and 515 dipoles, spherical inclusion. also works if scattered electric field, which...

Os problemas inversos da Geofísica geralmente podem ser formulados como um sistema de equações lineares. Tais são mal-postos, isto é, suas soluções condicionadas pelos aspectos existência, unicidade e estabilidade. A tomografia sísmica é uma tipo especial problema inverso, que permite estimar função a partir integral linha mesma. Na tempos trânsito, objeto deste trabalho, incógnita do problema, ou seja, o vetor parâmetro modelo, distribuição bidimensional vagarosidades, obtida conhecimento...

Summary It is present an efficient parallel algorithm for the inversion of 3-D gravity data, which goal to estimate depth a sedimentary basin in density contrast varies parabolically with depth. The efficiency methods applied interpretation basins depends on number data and model parameters be estimated, making it very poor when large. We simulation results synthetic inspired real situation, taking advantage Levenberg-Marquardt implemented using both MPI OpenMP. Lanczos bidiagonalization...

Summary Generalized simulated annealing (GSA) is an optimization technique for locating the global optimum, which contains both classical (SA) and fast (FSA) as particular cases. In this paper, GSA was applied to invert gravity data obtain geometry of 2D basement relief. The behaviour algorithm its comparison with modified particle swarm (PSO) were studied by simulations synthetic data. results obtained from inversion show that PSO schemes give similar results. However, calibrating algoritm...

O imageamento sísmico em profundidade é um desafio áreas geologicamente complexas, onde a velocidade sísmica apresenta variação lateral. Porém, para se obter sucesso no necessário que tenha uma estimativa confiável do modelo de velocidade. A estereotomografia ferramenta efetiva alcançar esse propósito. Também denominada tomografia inclinação, ela utiliza as vagarosidades e os tempos trânsito selecionados famílias fonte comum receptor comum. Nós avaliamos alternativa da construção...

PreviousNext No Access11th International Congress of the Brazilian Geophysical Society & EXPOGEF 2009, Salvador, Bahia, Brazil, 24-28 August 2009Critério da Validação Cruzada Generalizada na Escolha do Parâmetro Ótimo: Aplicação em Tomografia Linear de Tempos TrânsitoAuthors: Naiane Pereira OliveiraAmin BassreiNaiane OliveiraIF/UFBA CPGG/UFBA and Amin BassreiIF/UFBA CPGG/UFBAhttps://doi.org/10.1190/sbgf2009-296 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack...