A Robust Fluid Identification Technique based on Frequency-Dependent AVO Inversion

Abstract

Summary Fluid identification using dispersion attribute of seismic data is critical for the reservoir exploration. Frequency-dependent amplitude variation with offset (FAVO) inversion method is an effective approach to estimate seismic dispersion characteristics from pre-stack seismic gathers of partially fluid-saturated reservoirs. However, existing methods neglect this problem that extracting dispersion information directly from seismic data will introduces uncertainty into the inversion results due to the fact that velocity dispersion is caused by numerous elastic and an-elastic subsurface mechanisms. For this reason, we propose a robust fluid identification technique, which is more robust and has higher precision due to the addition of P- and S-wave velocity ratio constraint to the conventional frequency-dependent AVO inversion. In this study, the theoretical model test proves that the P- and S-wave velocity ratio has a significant influence on the prediction results of frequency-dependent AVO inversion. The test results of well-side trace also show that the prediction results of the improved method have higher accuracy due to the constraints of prestack AVO inversion results. This study provides a new idea for improving the accuracy of frequency-dependent AVO inversion.