Abstract

The effect of wavelet phase rotation on post inversion in X-field Niger Delta has been investigated. This paper demonstrates the influence of wavelet phase employed in model based seismic inversion. It presents the problem associated with variation in wavelet phases employed in post-stack model based seismic inversion which affect the discrimination of litho-fluid contrast from inverted seismic volume. The study was carried out using 3D post stack seismic data and well logs from three (3) exploratory wells in the study area. The data was inverted into acoustic impedance (P–impedance) using five different wavelets with 0, 15, 30, 45 and 60° phases for each inversion process. The inverted P-impedance slices result for the different wavelet phases were compared and the effect of each wavelet on the inverted section was deciphered. Small decrease in impedance error was observed for zero degree (0°) and minimum (15 to 30°) wavelet phase. Alternatively, inverted P–impedance section using 45 and 60° wavelets phase depict high error in the impedance and less correlation coefficient with increase in the synthetic error. This study thus recommends zero degree (0°) or minimum phase (15 to 30°) wavelets for interpretation in the study area as the degree of variation in input wavelet greatly affects the inverted acoustic impedance results.

Key words: Niger Delta, wavelet, well logs, seismic data, stack inversion