In Neogene geologic settings, seismic resolution plays an important role in the static characterization of large stratigraphically complex reservoirs. Attenuation of high frequencies due to absorption and scattering of waves propagating through the subsurface contributes to the loss of seismic resolution, resulting, in particular, to a poor delineation of thin beds. This case history comprised the resolution enhancement of seismic data from one petroleum field located in the southern Gulf of Mexico. We applied discrete wavelet transform-based multiresolution analysis to identify frequency components in the data that required spectral enhancement. The resulting enhanced power spectrum contains a higher frequency content, which made it possible to identify new heavy oil (11°–23° API) reservoirs located in thin sandstones of deltaic sedimentary environments. The methodology used here helped us to cope with the attenuation problem.

Scattering and diffraction of P and SV waves caused by parallel oriented cracks located near to a free surface are investigated in this work. The Indirect Boundary Element Method (IBEM) was applied for studying the wave propagation phenomena in a half-plane model that contain the cracks. Various incidence angles of P and SV waves are considered. Sometime before it has been reported that a near free-surface crack generates scattered surface waves whose amplitude spectra show conspicuous resonance peaks. Such effect has been attributed to local resonances originated in a virtual layer between the shallowest crack and the free surface. For our case of two parallel crack system, where cracks are located at different depths, the amplitude spectra show additional peaks, which can be associated with the presence of the second crack. Given similar sizes between these two cracks, the characteristic resonance frequency observed at the free surface corresponds mainly to the equivalent layer formed by the shallowest crack and the free surface. However, when the deepest crack becomes sufficiently large with respect to the shallow crack, two resonance characteristic frequency peaks appear in the measured spectra at the free surface. Some examples including a three crack system are also illustrated in our work. The identification and characterization of the seismic response for the scattered field generated by the second and third crack has been an intricate task and, the time domain interpretation of traces becomes quite complicated. The results in this paper have been validated against some other reported from classic papers. In order to show the seismic response and multiple scattering effects due to the presence of systems of cracks, calculations in frequency and time domain are provided.

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Multiresolution analysis, based on the discrete wavelet transform, is here incorporated in seismic signal processing. This analysis technique enables decomposing a seismic signal, in different frequency bands, and thus to analyze the information contained in these frequency bands. Multiresolution analysis allows visualizing in the time domain the information contained in the frequency bands. Wavelets commonly used in the discrete wavelet transform present an overlay between scales, this constitutes an aliasing effect that gives rise to spurious effects. Vaidyanathan wavelet minimizes the overlay between scales. We applied this wavelet to synthetic data and to a 3D seismic cube. Accordingly, spurious effects from aliasing generated by overlay between scales are minimized with the Vaidyanathan wavelet.