Carbon Dioxide Capture, Utilization & Sequestration Technical Section

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  • 1.  Correlation permeability - Capillary entry pressure

    Posted 04-10-2024 07:13 AM

    Dear SPE colleagues,

    I am currently pursuing a PhD project where I numerically modell the injection of supercritical CO2 into a porous aquifer. I would like to carry out parameter sweeps looking into the influence of varying permeabilities, and for that matter would like to implement a correlation into my model correlating a given permeability to a reasonable capillary entry pressure. Are any of you aware of such a correlation? Any input is much appreciated!

    Best wishes,

  • 2.  RE: Correlation permeability - Capillary entry pressure

    Posted 04-11-2024 02:07 AM
    Hello Daniel,

    If you are studying the influence of varying permeability on injection of
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    channels into the target formations from the motherbore. We see extreme
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  • 3.  RE: Correlation permeability - Capillary entry pressure

    Posted 04-12-2024 11:33 AM

    Dear Daniel,

    You've asked a simple question.  And, as always, the answer is quite complicated, and is specific to lithology.  I will try to give a detailed answer (even an equation) but want to make sure I cover the caveats to avoid generalization.  I anticipate that there are other approaches which may be better than what we use.

    As you know, we typically obtain Pc data through mercury injection tests.  There is always an error due to end-effects which is most pronounced at the entry pressure.  To overcome this problem, we plot log10(Pc) versus log10(Sw*).  Fit a straight line through most of the pore volume.  Obtain pore throat size distribution.  By extending the line to Sw*=1 we obtain Hg-Air entry pressure and convert it to oil-water Pce.

    In the past, for decent permeability rocks (~100 mD liquid perm) we found the oil-water entry pressure to be quite low (~1-2 psi).  For high permeability rocks it is practically zero.  When the calculated values are within the range of experimental error bars, it does not make sense to seek correlations.  This, I believe, is the primary reason why in literature we do not find entry pressure correlations for rocks with decent permeability.

    To find a correlation, we must investigate tight rocks with less than 1 mD (liquid perm), which may not apply to your CO2 storage study.  We do have data (for specific lithologies) but they do not span the full permeability range for generalization.  So, we must select the equation for correlation.  I assume that it follows the power law so that it may be somewhat extrapolated to higher permeability values.  Here is an (approximate) simple oil-water equation for you:

    Pce(psi) = 10.0 / SQRT [k-liquid (mD)]

    Good luck in your studies and best regards.

    Chet Ozgen

    Chet Ozgen

  • 4.  RE: Correlation permeability - Capillary entry pressure

    Posted 04-12-2024 03:01 PM


    Great project!
    My advice: be careful.
    Working for Chesapeake Energy I saw a LOT of MICP data in tight and unconventional shale rocks. There is a lot going on with entry pressure for these types of rocks. For example:
    Follow the publications of these people regarding use of MICP:

    Jeff Baldwin
    Oklahoma, USA