Application of time-frequency decomposition method in the study of gas reservoir in the Sergipe-Alagoas Basin

Abstract

The sedimentary basin of Sergipe-Alagoas, located on the Brazilian east bank, presents one of the most complete stratigraphic sections of the Brazilian continental margin. Hydrocarbon exploration activities began more than 50 years ago. The recent discoveries of hydrocarbons (gas and oil of high API grade) in turbiditic reservoirs of deep waters have further awakened the exploratory interest of the basin. Problems related to the processing and interpretation of seismic data have always received great attention from the scientific community. Currently, the use of time-frequency decomposition methods of the seismic signal is of great interest. Spectral decomposition has been widely used in reservoir characterization, such as determination of layer thickness, stratigraphic visualization with seismic attributes and identification of low frequency anomalies associated with the presence of gas. The mechanism causing these anomalies is not yet well known, but they are often attributed to the high attenuation of gas filled reservoirs. The approach used for spectral decomposition combines the maximum entropy method and the Wigner-Ville distribution, based on the idea of the Burg method that uses the prediction error operator to extend the Wigner-Ville kernel sequences by applying the Fourier transform to each extended sequence, thus allowing to obtain the Wigner-Ville distribution of maximum entropy.