Speaker
Description
The use of the porous plate method for the measurement of capillary pressure is time consuming, from weeks to months. In this study we present an apparatus and a procedure that reduce drastically the duration of such measurements to around one day.
The main application is the determination of drainage capillary pressure curve by gas or oil displacement of water or brine, leading to the determination of entry pressure and pore size distribution, as an alternative to the toxic mercury injection (MICP).
Our main improvement was to design an equipment allowing the use of very thin rock samples (3-6 mm) without the need for a confining pressure. Instead of step injection, a programmed continuous pressure increase leads to a smooth Pc curve.
With gas injection, capillary pressure curves up to 35 bar (525 psi) – corresponding to 50 nm minimum pore diameter – were obtained in one day on 3 mm disk samples. The results are in good agreement with the pore size distributions measured by mercury injection for samples with permeabilities ranging from one microDarcy to several Darcy. The apparatus have also been tested to determine the pore size distribution of thin membranes and electrodes. Moreover the apparatus can be used for the determination of the resistivity index like with a standard porous plate apparatus.
For quality control, the experiment is simulated with the two-phase flow simulator CYDAR to adjust the rate of pressure increase in order to keep the pressure drop across the porous plates small compared to the capillary pressure.
Compared to mercury injection, the main drawback is the limitation in pressure corresponding to a minimum pore diameter of around 50 nm. However, this pressure range is in the domain of petroleum reservoir applications, CO2 sequestration and H2 storage.
| Country | France |
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