Temperature, differential pressure, and porosity inversion for ultradeep carbonate reservoirs based on 3D rock-physics templates

Ultradeep carbonate reservoirs have high temperatures and pressures, complex pressure/tectonic stress settings, and complex pore structures. These conditions make their seismic detection and characterization difficult, particularly if the signal-to-noise ratio is low, as is the case in most situations. Moreover, the high risk of deep-drilling exploration makes it impractical to carry out normal logging operations. We have developed a temperature-differential pressure-porosity (TPP) rock-physics model based on the Biot-Rayleigh poroelasticity theory to describe the wave response of the reservoir. A preliminary analysis indicates that temperature, pressure, and porosity are well correlated with wave velocity and attenuation. On the basis of this theory, we have built 3D rock-physics templates that account for the effects of TPP on the P-wave impedance, VP/VS ratio, and attenuation. The templates are calibrated with laboratory, well-log, and seismic data of the S area (Shuntuoguole uplift...