Integrated prediction of deep-water gas channels using seismic coloured inversion and spectral decomposition attribute, West offshore, Nile Delta, Egypt

Abstract

ABSTRACT In the West Delta Deep Marine (WDDM) concession many important gas reservoirs have been recently discovered. To improve the possibility of discovering new natural gas resources, an integrated prediction method approach is used in this study to identify the deep-water gas reservoirs. Post-stack seismic coloured inversion and the spectral decomposition attribute, combined with composite logs of five wells, are used to indicate the lateral and vertical variations of the gas channels in El Wastani Formation. Data conditioning and petrophysical analysis are performed. Both techniques help and improve visual evidence to detect gas channels. Coloured inverted seismic profile show relatively low impedance zones represent the gas channels. Spectral decomposition attribute solves the problem related to thin gas-sand layers through three different frequency magnitude values. The spatial distribution of the gas-channels properties indicates a good calibration at the well location with the effective porosity in the range of 15–35%. Comparing the results of the coloured seismic inversion with the spectral decomposition attribute, the low-frequency range through the spectral decomposition analysis is consistent with the low impedance values represents the gas channels. Furthermore, the methodology followed in the current study is advantageous to identify the gas reservoirs in various basins with similar geological settings.