DarcyPress: measurement of gas permeability under confining pressure on small rock samples
- Dry and clean samples.
- Size: 5-10 mm. Larger samples can be cut. Special procedure can be used for 2 mm sample.
- Permeability: 0.1 nanoDarcy (10-22 m2) to 10 Darcys.
- Confining pressure: 50 to 500 bar.
- Gas pore pressure: 0.1 to 10 bar.
The rock sample is embedded in a viscous polyester resin that does not enter into the pores.
After curing, a 2 to 5 mm disk is cut and polished.
The disk is placed in a core holder under confining pressure and the transverse permeability is measured.
- High permeabilities are measured using a standard pulse decay method.
- Low permeabilities are determined with a modified steady-state method with gas flow rate measured at outlet to avoid errors due to leaks in the system.
For stratified rocks, permeability parallel to the strata can be measured after coating the sample faces.
Data acquisition and interpretation
- Performed using the software CYDAR.
- User friendly; runs on PC (XP, Vista, W7).
- Automatic reporting: all results are exported to an Excel file.
Duration of measurements (batch of 12 clean samples)
- Transverse K: approximately 6 hours of work, with a total duration of 2 days (waiting time for resin curing and rock drying after slicing).
- For parallel K: time is doubled.