The Influence of Attenuation on Frequency Component of Seismic Signals

The nature of the frequency response depends strongly on the AVO behavior at an interface. In order to understand and predict the seismic response to fluid saturation for Class IV sands, we performed Synthetic geological models with a hydrocarbon-bearing zone .The synthetic seismic sections were produced by performing offset acoustic ray-tracing in GX Technology’s GX-II 2D forward modeling package based on existing well log information close to the study area, which can effectively model the characteristics of attenuation and frequency-dependent reflection. We use S-Transform time-frequency signal analysis to transform the seismic data centered within a time window to the time-frequency domain and then sort the frequency gathers to common frequency cubes. we observe the characteristics of the seismic low-frequency shadow in the common frequency cubes. Reservoir simulations reveal that the main mechanism of seismic low frequency shadows is attributed to high attenuation of the medium to high seismic frequency components caused by absorption in the hydrocarbon-filled reservoir. After modeling and validation of the technique with synthetic data, seismic analysis supported with SD technologies was performed to evaluate prospects located in real data. Results from a practical example show that it is possible to identify Athe reservoir by the low-frequency shadow.