THICKNESS ESTIMATION USING GRADIENT OF SPECTRAL AMPLITUDES FROM SPECTRAL DECOMPOSITION

摘要

This paper presents a novel approach for estimating thin bed thickness by using gradient of spectral amplitudes resulting from spectral decomposition. The gradient is calculated from the differences between amplitude spectrums at two adjacent frequencies. The technique is based on the concept that seismic reflections from a thin bed have characteristic signatures in the frequency domain. Thicker beds have shorter period spectral notches than thinner beds have. Consequently, steeper gradients of spectral amplitudes represent thicker beds and lower gradients represent thinner beds. In this paper, the Discrete Fourier Transform (DFT) method was used for spectral decomposition. The application of the technique for mapping thin bed distribution is presented. The gradient of spectral amplitude has been found to have better correlation to thickness than the conventional spectral amplitude.