Porous Grain Model for Carbonate Reservoir and Its Application

Rock physics studied the link between reservoir properties, such as porosity, density, saturation, fluid type and the seismic response. Establishing of a carbonate rock physics model is more difficult because pore systems are more complex in carbonate rocks than they are in siliciastics. In this study, we offer an effective-medium model for estimating the seismic properties of low or mid-porosity carbonate. In this model, we consider carbonate sediment as a pack of porous elastic grain by using the differential-effective-medium(DEM) model to calculate the sediment grains with different pore types, then using upper Hashin-Shtrikman bound to compute the elastic moduli of a pack of these spherical grains. An example from the carbonate reservoir of Tarim Basin, northwest of China indicate that the result of this model match log data very well.