Abstract

Because the seismic wave propagates through the subsurface, part of the elastic energy eventually ends up as heat energy. This phenomenon is known as absorption (or anelastic attenuation). The factors causing anelastic attenuation include fluid movement and grain boundary friction. The seismic quality factor (Q) quantifies the anelastic attenuation and is commonly used in assisting reservoir characterization. However, current Q-estimation approaches are mainly implemented on a poststack seismic volume. The Q-estimation approaches applied to poststack seismic data assume that the seismic data are normal incident reflections, and they do not consider the effect of the travel path on seismic attenuation. In theory, the attenuation degree of the low-frequency component should differ from the attenuation degree of the high-frequency component for large-offset seismic data. We have developed a method to qualitatively estimate seismic attenuation in the prestack seismic domain. A continuous wavelet transform is used to extract the low- and high-frequency components for the common-reflection point gathers. The difference between the amplitude of the low-frequency component and the amplitude of the high-frequency component is used to measure the seismic attenuation factor. We have determined the effectiveness of our method by applying it to synthetic and real seismic data.

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