Low permeability measurements on small samples and drill cuttings.
- Interpretation of a gas pressure drawdown (improved GRI method).
- Precision is under the nanoDarcy and up to 500 nanoDarcy.
- The samples are put under pressure in a small chamber.
- The pressure is quickly decreased by opening a valve in a second chamber.
- Permeability is derived from the interpretation of the transient pressure.
A benchmark on several commercial measurements using the standard Gas Research Institute method has shown several problems (SCA 2019). A collaboration between TOTAL and CYDAREX has improved the GRI method and the equipment (SCA2021):
- Sample initially under pressure allowing a small variation of pressure inside the sample for a better determination of Klinkenberg correction.
- Filling of the empty space with a fine powder to reduce thermal effects linked to the decrease of pressure.
- Filling of the drawdown vessel for better temperature regulation with metallic chips.
- Mass of samples between 2 and 5 grams, single sample or granular.
- Cuttings or crushed samples with 1mm minimum size.
- Pressure up to 40 bar.
- Permeability on crushed samples below the nanoDarcy, and up to 500 nanoDarcy.
- Numerical interpretation with single or double permeability models.
- Automatic history matching using the software CYDAR.
- Fast and easy measurement.
- SCA2010-32: Permeability measurement on small rock samples, Lenormand, Bauget, and Ringot.
- SCA2019-016, Low permeability measurement on crushed rock: insights, Profice and Lenormand.
- SCA2021: to be published.