Full-frequency Band Velocity Prediction Model and Its Application on Seismic Reservoir Prediction

Differential effective medium (DEM) model is a recognized effective media model to predict P- and S-wave velocities of rocks with complex pore shapes. But it simulates very high frequency saturated rock behavior and is only appropriate under ultrasonic laboratory condition, which limits its applicability for reservoir prediction due to the effect of velocity dispersion. To solve the problem, a full-frequency velocity prediction model is proposed by coupling DEM model with a dispersion theoretical model (microstructure model) by establishing the transform relationships between the parameters of the two models. Two sets of experimental measurement data are used to validate the rationality of the full-frequency model. Finally, the model is applied to seismic reservoir prediction. The predicted velocities at ultrasonic-, sonic-, and seismic-frequency bands are respectively used for AVO analysis and prestack inversion. The analysis results show that seismic-frequency band velocities have the best reservoir prediction capability. Consequently, a heuristic thought about the rationality of appying logging velocity to well-to-seismic calibration is presented.