GeolOil is designed from scratch to handle variable matrix properties.
Any "constant" parameter in any equation can be a curve in its own right.
The *Sequential Petrophysical Functions* module has a large built-in set
of 77 classic pre-defined equations and correlations for:

- Curve transforms (9 equations)
- Vshale calculations (8)
- Porosity (18)
- Permeability (7)
- Temperature and Resistivity (9)
- Water Saturation (13)
- Geomechanics (9)
- Mineral Solvers, 4 models. (Other software usually add Mineral Solvers as a separate module for purchase)

As an example consider a case of a clastic reservoir where the interpreter decides to change the reference GR value for clean sandstones (or use a variable curve instead of a constant). Then the sequence to update the water saturation curve with a single click must follow four calculations in the chained sequence:

- Update the linear Gamma Ray index curve (IGR) to account for the updated clean sandstone GR value or variable curve.
- Update a possible non linear Vshale model like Larionov, which depends on the updated curve of IGR.
- Update the effective porosity for its change in VSH.
- Update the effective shale corrected water saturation model SW like Simandoux, which depends upon VSH and PHIE.

The figure below shows the main function panel list

The figure below shows the panel to define the computed output curve

The figure below shows some predefined functions for porosity

The figure below shows a log display with the updated petrophysical interpretation