Reservoir causes energy density anomalies of seismic signal which could be utilized to detect reservoirs. Teager energy in time-frequency domain is derived from generalized S-transform in this paper. Analysis of real seismic traces shows that Teager energy distribution in time-frequency domain possesses higher time-frequency localization and temporal resolution. 3D seismic data demonstrates that ITDE can depict reservoir location, and characterize the spatial distribution and internal heterogeneity of reservoirs. ITDE can be used as a new instantaneous spectral attribute in reservoir characterization.