Rock Physics Module (RPM)

Rock Physics Module (RPM) is a rock physics software add-on module for PowerLog®. It integrates the well log analysis of PowerLog with rock physics elastic modeling. RPM enables a fundamental modeling approach—a petrophysical rock model is used to derive the effective elastic rock properties from fluid and mineral parameters, as well as rock structure information. The model parameters are calibrated by comparison of the synthetic to the available elastic sonic logs. RPM supports inclusion models and contact models including Stanford cemented spheres scheme 1 and 2.

Rock Physics Modeling

RPM plays a significant role in seismic AVO analysis. A common problem in AVO analysis is the fact that DT logs are available but DTS logs are not. There is therefore a need to generate quality synthetic shear sonic logs that correspond to the compressional sonic and density logs. The consistency of the elastic logs is essential for the success of an AVO seismic analysis or inversion.

The propagation of seismic waves in fluid-filled porous rock depends on the rock matrix composition and structure, as well as the properties of the pore fluids. A correct velocity estimation must therefore also depend on these factors. RPM enables a fundamental modeling approach - a theoretical rock model is used to derive the effective elastic rock properties from fluid and mineral parameters, as well as rock structure information. The model parameters are calibrated by comparison of the synthetic to the available elastic sonic logs.

In addition to a number of simple averaging methods (Wyllie, Voigt, Reuss, Hashin-Shtrikman), RPM contains the following rock physics algorithms:

• A fast approximation of Xu & White’s model
• Greenberg & Castagna’s relation
• Gassmann’s equation
• Gardner's relation
• Modified upper & lower Hashin-Shtrikman method
• Fluid-properties estimation based on Batzle & Wang

Once a rock model is constructed, fluid-substitution studies and invasion correction can be easily performed. The rock model also enables prediction of elastic curves for lithology parameters that are not present in the wells.

In addition to rock physics modeling, RPM allows you to estimate anisotropy parameters from deviated well curves and correct sonic curves for anisotropy influence.