Capillary pressure & 2-phase properties

The SatuDict module deals with the distribution of two distinct fluid phases (gas or liquid) in porous materials. Saturation with these fluid phases alters the properties of the porous media, such as flow permeability, diffusivity, thermal conductivity, and electrical conductivity. These properties come to depend on the saturation of the media, and are considered as relative or effective.

The SatuDict module simulates the distribution of two immiscible fluid phases where capillary forces are dominating. SatuDict computes saturation-dependent material properties, such as capillary pressure curves, relative permeability, relative diffusivity, relative thermal conductivity, relative electrical conductivity, and resistivity index. Additional post-processing of the results allow to fit Thomeers model for Mercury Intrusion Capillary Pressure (MICP) curves or fit Archie's law for resistivity index.

• Simulation of entire hysteresis cycle and relative permeability under mixed-wet conditions of rocks.
• Resistivity index and exponents m and n, including thin water films of rocks.
• Mercury intrusion and extrusion and unresolved porosity of rocks.
• Capillary pressure and fluid distributions for personal care and hygiene materials.
• Electrolyte intrusion in battery electrodes.
• Relative gas diffusivity in gas diffusion layers (GDL) for fuel cell design.

The SatuDict module predicts two-phase flow using a Pore Morphology Method-based algorithm and it is a hybrid of geometry-based simulations, i.e., morphological operations and physics-based simulations.

The result of the Pore Morphology Method (PMM) is a sequence of quasi-stationary two-phase fluid distributions, which are used to compute the saturation-dependent properties. The method allows to consider single or multiple contact angles at pore-solid interfaces. In addition, mixed wettability is considered where contact angles smaller and larger than 90° are present within the same structure.

SatuDict provides a quasi-stationary and a dynamic method where the dynamic method captures fluid distributions between two quasi-stationay states. This allows to increase the number of computed steps with more accuracy.

The capillary pressure curve is computed based on the predicted fluid distributions using the Young Laplace equation. For each fluid distribution, the layered fluid saturation is computed as post-processing to provide information about the penetration depth.

Mercury intrusion (MICP) and mercury extrusion (MECP) are both calculated using the PMM and the Young-Laplace equation.

The MICP simulation results provide information on the pore throats sizes, and the MECP about the pore bodies. Additionally, the residual mercury remaining in the pore space is determined.

For mercury intrusion, it is possible to apply the Thomeer model, for the prediction of the non-resolved porosity, the displacement pressure, and a pore geometry factor.

The relative (and effective) permeability is predicted using the fluid distributions and the flow solvers which are also available in FlowDict. The relative permeability is predicted for the invading and displaced fluid phase separately.

Similar to the relative permeability, the relative gas diffusivity is predicted using the fluid distributions and diffusion solvers available in SatuDict. The relative diffusivity is predicted for the invading and displaced fluid phase separately.

The relative thermal conductivity is predicted based on the fluid distributions and the conduction solvers, which are also available in ConductoDict.

The resistivity index and relative electrical conductivity are predicted based of the fluid distributions and the conduction solvers available in ConductoDict.

In addition, thin water films smaller than the voxel length are considered in the simulation where mixed voxels are introduced at oil-solid interfaces. As post-processing, the Archie's parameters -  namely the saturation and cementation exponents - are computed based on Archie's law.