Re: How to establish core calibration constant in swi versus
For Q1 I don't have an answer.
For Q2 I can comment the following: If your FZI vs porosity plot is showing a lot a scater you're probably dealing with multiple flow units or facies. At least that is what FZI let's you investigate. Ideally you should see seperate clouds that you or your geologist can relate to different genetic facies.
If you can link it to facies and they have a geological meaning you could distribute them through your model. Then, maybe each facies might have a different water saturation character and a different irreducable water saturation.
You could also check if you are dealing with total porosity or effective porosity. Also, are you comparing core data to log data. Can you crossplot FZI versus vshale? Does that help?