A S-wave Spectral Decomposition Hydrocarbon Detection Method Based on P-wave and S-wave Source and Its Application

Abstract

S-wave source vector exploration is a promising technology in future seismic exploration. Conventional P-wave and S-wave joint inversion methods for hydrocarbon detection are limited in some aspects. First, P-wave and S-wave joint inversion is mainly based on the converted wave theory, but no theoretical support for S-wave generated by S-wave source. Second, the inversion method is complex and difficult to operate. Because P-wave and S-wave from S-wave source should accurately match with each other, without an effective approach, it has to follow the method of P-wave matching with converted wave, so it is not helpful to extensive application. This paper proposes a comprehensive s-wave spectral decomposition hydrocarbon detection method based on p-wave and s-wave source. First, the velocity ratio of P-wave to S-wave (Vp/Vs ratio) is derived to be equal to the frequency notch period ratio of P-wave to S-wave, and approximately equal to the dominant frequency ratio of P-wave to S-wave. Second, spectral decomposition is conducted at the target layer to obtain the tuning frequency spectra of P-wave and S-wave seismic data, respectively, and the dominant frequencies of P-wave and S-wave are automatically identified. Third, the Vp/Vs ratio and Poisson's ratio are calculated according to the dominant frequency ratio of P-wave to S-wave for final hydrocarbon detection. This method is independent on well data and accurate matching of P-wave with S-wave data, it is simple, quick and efficient. It’s widely applicable in any areas more or less explored. Application in an oilfield in western China has obtained effective results.