Integrated Rock Physics Modeling

Fluid and rock property analysis, modeling, and substitution

Ω-Reservoir technologies and workflows for signal processing of seismic data provide an interactive environment for building and evaluating rock physics models for use in inversion, seismically driven reservoir characterization, and 4D time-lapse studies. Rock physics modeling also allows the user to perform rock property and fluid substitution as part of 3D and 4D feasibility and calibration studies.

Rock physics model building

The model building functionality allows execution of rock physics models by calling predefined theoretical or empirical models from an extensive library or by implementing new user-defined models. This iterative process relies on the skill of the analyst and uses an advanced rock physics calculator that provides an interactive analysis and viewing interface.

Fluid substitution

The fluid substitution functionality allows generation of new compressional and shear sonic waves, as well as density under different saturation conditions (fluid type, pressure, and temperature). The fluid substitution is implemented in a form where the typically unknown, dry rock bulk modulus is not required. By algebraically eliminating the dry rock modulus from the Gassmann equation, all that is needed is compressional velocity, shear velocity, and density of the rock, plus bulk modulus of the fluid mix under in situ conditions and the porosity and mineral bulk modulus.

Estimating the compressional velocity, shear velocity, and density for the new reservoir conditions requires only the bulk modulus of the new fluid mix under the new temperature and pressure. The fluid properties are calculated using the Batzle and Wang empirical relationships. The fluid moduli are adiabatic estimates appropriate for dynamic wave propagation and are significantly different from the isothermal fluid moduli used in reservoir engineering. An easy-to-use drop-in and drop-out user interface panel allows rapid fluid substitution.

Applications

Integrated rock physics modeling is used in many different applications and workflows, such as

• seismic reservoir characterization (lithology, saturation, porosity, and others)
• 4D feasibility and modeling
• AVO and AVOZ modeling
• log calibration, generation, and rejuvenation
• pressure prediction
• subsidence and borehole stability
• fracture detection, orientation, and mapping
• permeability inversion.