Permeability to gas can be measured in a variety of ways, the expected permeability range of your samples will determine which method is best suited to your needs.
Permeability to gas can be measured in a variety of ways, the expected permeability range of your samples will determine which method is best suited to your needs
The original process that was develop based on Darcie's law, permeability is calculated by knowing the flow rate of a given gas at a known pressure drop across the sample. By using a controlled back pressure system this test can be extended to determine a Klinkenberg corrected Permeability value using procedures set out in the original work by Klinkenberg et al
Unsteady State: Pressure Decay
The unsteady state method has grown in population as the need for quick reliable permeability below 1mD become necessary. A volume of gas at a known pressure is released into the sample and the pressure decay over time is measured, differentiation of the pressure decay curve over time allows for a Klinkenberg permeability to be determined. Ideally suited for samples 1D to 1mD
Unsteady State: Transient Pulse Decay
For ultra low permeability measurements the Transient Pulse Decay Method, where the time taken for a low-pressure pulse is measured to determine permeability. Ideally suited for samples 1mD to 10nD
All sample can be measured at a vaiety of net confining pressures to better simulate down whole permeaiblites.