Using frequency-dependent AVO inversion to predict the “sweet spots” of shale gas reservoirs
Abstract Shale gas is an unconventional hydrocarbon resource with huge potential. Using geophysical methods to predict “sweet spots” is the key to commercial exploration of shale gas. At present AVO technology is one of most widely used geophysical techniques to find shale gas reservoirs with high abundance. However, the effects of the dispersion of actual mediums are neglected by conventional AVO inversion. Recent experiments have shown that in gas-bearing strata, the dispersion may be rather remarkable. In this paper, we develop a frequency-dependent AVO inversion scheme, which includes seismic dispersion in real rock medium, to predict the “sweet spots” of shale gas reservoirs. Application of the inversion has been made to the shale gas in the south of Jiaoshiba area to test the validity. Comparing the results of the frequency-dependent AVO inversion and well production, we find that regions with high dispersion gradients correlate well with places with high production of shale gas. Therefore we conclude that the frequency-dependent AVO may be a workable approach to detect the “sweet spots” of shale gas reservoirs.