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Steady State and Unsteady State Permeability Measurements for Tight Rocks

Steady State and Unsteady State Permeability Measurements for Tight Rocks



Permeability measurements are important for reservoir modeling, reservoir depletion policies, and log calibration. At MetaRock Laboratories, we have designed an experiment to represent the subsurface reservoir mechanisms. Discern between matrix permeability and fracture permeability, measure them, and feed this information to dual porosity reservoir models is possible with our unsteady state system. Moreover, using the pulse decay method, porosity is calculated using Boyle’s law under stress. 

Our experiment is designed to measure permeability in intact ultra-low permeability rocks. Intact rock permeability analysis has many advantages over crushed rock analysis. For instance, permeability measurements on intact plugs prevent from doing rock fabric damage. Additionally, these steady and unsteady state permeability measurements are done using gas (CO2, N2) under supercritical conditions to avoid slippage and inertial effects and eliminate the need for Klinkenberg and Forchheimer corrections. 




  • Equipment specially designed to measure steady and unsteady state permeability in intact ultra-low permeability rocks using gas (CO2, N2) under supercritical conditions. 

  • Using the unsteady state, we are able to characterize pore volume changes with stress. 

  • Ultra-low resolution (~1 nano-Darcy). 

  • Custom metallic seals prevent any leaks that could affect permeability measurement. 

  • All system components (vessels, pumps, transducers, reference volumes, etc.)  are located inside an incubator in a constant temperature environment to achieve accurate and reliable gas PVT data. 

  • Permeability measurements under effective stress.  

  • Recoverable permeability (or hysteresis point) to see how the effective stress affects the permeability of the rock.  

  • Obtain accurate permeability calibration point. 


Recommended Sample Dimensions: 


  • Length: 0.5”   

  • Diameter: 1” 

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