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Asalaam o Aalikum,
Dear Sir,
I am interested in determination of permeability using wireline logs. Sir, how we can find irreducible  water saturation from wireline logs. In all empirical relations, (Whyllie and Rose, Timur, Coates)Swirr is involved.
Another thing to ask is, In article, "Porosity-preserving chlorite cements in shallow-marine volcaniclastic sandstones: Evidence from Cretaceous sandstones of the Sawan gas field, Pakistan", Helium porosity and Core porosity is given which have significant difference from each other. Why there is  difference between PHI-Helium and PHI-Core for same core sample? (I have determined PHI_ND which was matching good with PHI-Helium).
Thanks a lot for your time Sir.

Hi Atif,

For irreducible water saturation you should ideally have a core but if you don't have core Swirr then you can calculate it by, SWirr = 1(((C**2)*(PERM**1/2))/((100*PHIE)**2))+1. Usually you include a core to well log calibration step to derive your Coates coefficent (C). Common numbers for this coefficient are 8-11 depending on your porosity to permeability transform.

How is PHI-core calculated? I have not seen the article you mentioned but we can dig into why they are different from each other. You need to provide how much the calculations were performed. You may find this link helpful.




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Syed Anjum Shah


I would love to answer questions related to petrophysics which includes conventional as well as unconventional reservoirs. I will avoid answering NMR, CMR and acoustic processing techniques as these are not my area of experties.


Petrophysics and source rock maturity modelling are the fields of great interest. Petrophysics includes, experience in single and multi-well interpretation including thin-beds, carbonates, complex mineral reservoirs, LRLC pay reservoirs, Shale Gas plays. Logging program creation. Operations support. Core analysis. Mud log analysis. Geomechanical data integration for well stability, placement, and completion type.

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Msc Geology 2006

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