Abstract: Restricted by the low resolution of seismic data,the identification of the top and bottom of a single sand body is difficult in the composite superposed sand bodies of the Guantao Formation in the Bohai S oil field.Moreover,in the time-space domain, sandstones with similar seismic reflection characteristics have very different fluid types,and the oil-water relationship is very complicated. In view of such a situation,based on the two-phase medium theory and the theory of viscous dispersion wave equation,the authors first carried out the time-frequency analysis of the generalized S transform,and selected the low-frequency and high-frequency attribute bodies with reference to the seismic reflection characteristics of the drilling well.Secondly,the top and bottom of the reservoir were accurately identified.Then the analysis of the difference of the spectrum characteristics of oil and water was conducted.The result shows that the seismic responses of the oil and water layers in the frequency domain have obvious characteristics,and the frequency-type attributes are more sensitive to the high-frequency attenuation of seismic waves.By optimizing the low-frequency and high-frequency attribute volume data of the main oil layer of the oil field and the plane data of the spectral attenuation difference between the top and bottom of the reservoir,a new fluid identification factor was jointly constructed to identify oil and water and achieved better results to help the remaining deployment and implementation of more than 10 development wells.