Porosity and Pore-Type Estimation from Seismic Data Using the Xu-Payne Multi-Porosity Model for Carbonate Reservoir

Carbonate reservoir has complex pore structure. The popularXu-Payne multi-porosity model has been widely used to quantitatively characterize pore-type distribution from logging data and experimental data. But it remains a great challenge to perform the pore-type inversion from seismic data while using the Xu-Payne model because accurate porosity and saturation can not be pre-given like well observations. In this paper, we present a two-step method to estimate the porosity and saturation and quantitatively characterize pore-type distribution from seismic data for carbonate reservoirs. Firstly, the pore systems of carbonate reservoir are treated as single porosity system with an effective pore aspect ratio. The porosity, fluid saturation and effective pore aspect ratio are simultaneously inverted from the inverted elastic properties by integrating Gassmann equations and the differential effective medium analytical model. Secondly, the pore systems of carbonate reservoir are treated as triple-porosity system that the Xu-Payne multi-porosity model defines. The porosities of three pore types can be inverted using the inverted elastic and physical properties as input. The real application shows that the proposed rock physics modelling and inversion method can yield a good quantitative estimation of porosity and characterization of pore-type from well log data and seismic data.