The delimitation of the very fines lithologies from seismic data is a crucial problem in geophysics, indeed the presence of the noise in seismic traces can deteriorate information and hide important hydrocarbons accumulations. For that we have to try in this paper to use a recent technique developed by A.Arneodo and his collaborators which is the wavelet transform modulus maxima lines (WTMM) combined with the discrete wavelet transform (DWT), to denoising traces and characterize each amplitude in the seismic trace by an exponent of Holder. In order to separate information that is of a significant geological lithology variation with the various noises. Our application at VSP data shows that this technique is a powerful tool of processing.

[pt] Uma das principais etapas na exploração de petróleo é a definição de um modelo geológico que justifique a existência de uma acumulação de hidrocarbonetos. Ferramentas que possam aumentar o grau de precisão deste modelo são foco de constante estudo na indústria do petróleo. Neste contexto, recentemente, Partyka et al. apresentaram uma nova técnica que utiliza a decomposição espectral dos dados sísmicos para refinar o modelo geológico em termos de definição de espessura de camadas. Nesta pesquisa, essa técnica é estudada e testada, e é proposta a utilização da transformada S, desenvolvida por Stockwell et al., para localizar as componentes de freqüência no domínio do tempo. Os testes realizados com dados sintéticos apontam o uso da técnica de Partyka et al. para fins mais qualitativos, já que, quando os modelos dos testes são perturbados, as análises quantitativas ficam comprometidas. A transformada S mostrou bons resultados na localização das componentes de freqüência no domínio do tempo; no entanto, ela acarreta a suavização do espectro de amplitudes. Ao final deste trabalho é apresentado um exemplo da utilização da técnica em dados reais tridimensionais. / [en] One of the main steps in oil exploration is the definition of a geological model that can justify the existence of a hydrocarbon accumulation. Tools that can improve the precision of this geological model are a constant goal of the oil industry research. In this context, Partyka et al. have recently presented a new technique that uses spectral seismic data decomposition in order to improve the model's accuracy in terms of the thickness definition of geological layers. In the present research, this technique is studied and tested, and a use for the S transform is proposed to locate the frequency components in the time domain. The S transform was recently developed by Stockwell et al. The tests performed with synthetic data indicate that the technique developed by Partyka et al. provide a better qualitative response, because, when the models in the tests are disturbed, qualitative analyses are compromised. The S transform showed good results in locating the frequency components in the time domain, but it smoothes the amplitude spectrum. At the end of this work, an example of the use of this technique with real three-dimensional data is presented.