Seismic spectral decomposition and inversion for buried channels delineation: a case study from the Asmari Reservoir, southwestern Iran

Abstract

Dense data sampling in 3D seismic surveys provides a clear image from subsurface layers, but it may fail in the cases where the thickness of a layer is below seismic resolution (e.g. thin beds and channels). Seismic spectral decomposition and inversion are among methods that can help us to delineate and study the sub-seismic resolution features. This paper shows how the buried channels of the Asmari formation in an oil field located in southwest Iran were delineated and are studied using seismic spectral decomposition and inversion. The Gabor wavelet transform was used to divide seismic frequency spectra into eight bands out of which three frequency bands with central frequencies of 24, 29, and 35 Hz have been selected for RGB blending for its perfectness in exposing the channels. Several distinct channels were detected at 15ms interval below the top of the Asmari formation. The P-impedance data coincide with the findings further giving information on lithological aspects. Detailed delineation of the channels became possible by using the Matching Pursuit Decomposition (MPD) method. In order to delineate sub-seismic resolution features, spectral decomposition is used to transform time-domain seismic data into the frequency domain and then the special elements corresponding to these subsurface features are enhanced with spectral blending.