A tool for predicting the saturation of water and the size distribution of water and air in pores

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Terms

porosity Φ_pore (%) = total pore volume / total rock volume * 100

S_pore (%): the percentage at which the pore with a radius r is filled with water

Φ_water: The water content of the pore with a radius r (percentage of water volume to total rock volume)

For each pore radius, Φ_water (%) = Φ_pore (%) * S_pore (%) / 100

predicted water saturation (%) = total of predicted Φ_water (%) / total porosity (%) * 100

How to use

To perform a trial calculation, press the "Example" button and then the "Calculate" button .

To calculate using your data, enter values in the light blue cells ("total rock height", "grain diameter", "pore radius", "porosiy") and then press "Calculate".

If you are using a spreadsheet, you can copy and paste the data directly by making the first column the "pore radius" data and the second column the "porosity" data, and copying them at once (not separately).

You may try with a total rock height of 10 mm and a grain diameter of 200 μm, if these values are unknown.

If your data is "pore radius" versus "cumulative pore volume percentage (%) (final value = total porosity (%))", calculate the pore volume percentage (%) for each radius and enter it in the table.

At present, if the main pores have radii greater than a few μm, more accurate results can be expected by performing α correction using the default value of α. If the main pores have radii less than a few μm, there is a possibility that the α correction will significantly underestimate Φ_water.

This tool is most suitable for predicting the initial state when water permeates into the pores due to capillary action. Over time, the trapped air may gradually dissolve into the pore water, causing the size distribution of water and air to change. In the case of gases that dissolve easily into water, such as carbon dioxide, this change may be even faster.

For more details on the model, see Yokoyama et al. (2023) Size distributions of water and air in rock pores induced by capillary rise: experiments and modeling. Transport in Porous Media, vol. 148, 67-93.