Instantaneous spectral analysis: Detection of low-frequency shadows associated with hydrocarbons

Instantaneous spectral analysis (ISA) is a continuous time-frequency analysis technique that provides a frequency spectrum for each time sample of a seismic trace. ISA achieves both excellent time and frequency localization utilizing wavelet transforms to avoid windowing problems that complicate conventional Fourier analysis. Applications of the method include enhanced resolution, improved visualization of stratigraphic features, thickness estimation for thin beds, noise suppression, improved spectral balancing, and direct hydrocarbon indication. We have seen four distinct ways in which ISA can help in the detection of hydrocarbons: (1) anomalously high attenuation in thick or very unconsolidated gas…