Abstract: There are a large number of reef-flat reservoirs founded in South China Sea, which have the characteristics of deep burial, uneven oil/gas distribution and difficult exploration. Low-frequency shadow and frequency attenuation gradient are two time-frequency analysis methods based on theory of wavelet transform spectral decomposition, which are closely related with the fluid of reservoir, not only as important indicators of fluid identification, but also determining the lateral distribution of a reservoir, except for identification of its top and bottom boundaries. While as one of important methods for reservoir prediction, the wave impedance inversion can make use of the advantage of log data's high vertical resolution to effectively distinguish them. Therefore, combination of these two methods can be better to predict reservoir location in M region, and finely characterize the lateral and vertical distribution of reservoir and oil/gas enrichment range in higher accuracy of prediction.

Key words: reef-flat facies, frequency attenuation gradient, wavelet transform, time-frequency analysis, wave impedance inversion, reservoir prediction