Analysis and Application of Wave-induced Relative Pore Fluid Pressure in Poroelastic Rocks

Understanding the effect of reservoir petrophysical properties on wave-induced fluid pressure is crucial for fluid discrimination in seismic exploration. However, subsurface rocks typically contain multiple pore types filled with different fluids, and the resulting complexity of reservoir petrophysical properties limits effective pore-fluid identification. To elucidate pore-fluid pressure variations, a porous rock physics model is developed, introducing a relative fluid pressure parameter to quantify wave-induced pressure changes. This parameter reliably captures fluid pressure responses across diverse pore structures and provides a crucial foundation for accurate fluid identification. Our analysis shows that fluid mobility, along with heterogeneity in pore structure and fluid distribution, governs pore-fluid pressure. The relative fluid pressure is generally higher in cracks than in stiff pores, with both exhibiting pronounced sensitivity to gas-bearing reservoirs. The proposed relative fluid pressure acts as an intermediate parameter linking complex reservoir petrophysical properties to seismic responses, providing a fluid pressure-based approach for precise characterization of fluids in hydrocarbon-bearing reservoirs.