The pore geometry and saturation effects on the modeling elastic properties of carbonate rocks

Rock Physics studies can collaborate to identify the carbonate’s pore system heterogeneities, allowing the prediction of elastic parameters and seismic velocities in time-lapse modeling. This work is based on the effective medium theories and Gassmann’s model to characterize and classify porosity according to the pore types. The methodology was applied in the Glorieta-Paddock carbonate reservoir at the Vacuum field, New Mexico, to estimate elastic properties under dry and saturated conditions. The results indicated the greatest potential of Upper Paddock formation to store fluids and increased seismic sensitivity due to the interparticle pore aspect under the influence of microcracks in limestone, reflecting a lower stiffness rock and increasing seismic sensibility for fluid saturation. The Lower Paddock and Glorieta formations consist of dolomite with interparticle pore aspect under influence of spherical pore shapes, showed a reduction in seismic sensitivity due to the increase of rock stiffness. Under the conditions imposed in this study, we verified that the application of the effective medium theories, specially the KT model, proved to be better than Gassmann’s model to express seismic velocity anomalies.