Carbon Dioxide Capture, Utilization & Sequestration Technical Section

Hi Eric,

Thanks for your question. CO2-brine relperm has been a topic of research for at least 15 years and there are several literature papers available. However, as with any data in the literature it really pays to carefully consider the quality of the data and the applicability to your situation.

Before diving into literature papers it's worth revisiting the parameters that effect the relperms – which are primarily the wettability of the rock-fluid system and the characteristics of the porous media itself. For wettability there are papers which indicate that CO2-brine systems remain largely water-wet, except for rocks that contain a large amount of organic material (e.g. coal, bitumen) or have previously contained an oil charge that altered the wettability of the system. You could refer to this reference for example:
CO2 wettability of seal and reservoir rocks and the implications for carbon geo‐sequestration - Iglauer - 2015 - Water Resources Research - Wiley Online Library
Next the rock properties (e.g. tortuosity, porosity etc) would impact the relperms in the classical sense many of us are familiar with for water-wet hydrocarbon systems (e.g. a tighter rock would have a higher irreducible water saturation and the Corey exponent of the wetting brine phase would be higher).

With the understanding of wettability and the rock's characteristics I would suggest you can then start screening legacy (hydrocarbon-water) data for analogues. It is often the case that a lot of that data (so long as it is good quality) can be analogous for CO2-brine behaviour.
Finally, I would look to complement the summarised analogue hydrocarbon-brine data with some CO2 specific data – either through direct measurement or through a review of the CO2 literature. I have not worked the Appalachian Basin personally but there are high quality CO2 relperm datasets published from universities including Wyoming (Prof. M.Piri), Stanford (Prof. S.Benson) and Imperial College London (Prof. M.Blunt, Dr S.Krevor). As with any SCAL data set I would be checking to see that the report includes raw data (effluent volumes and pressure drops versus time, in-situ saturation monitoring by x- or gamma-ray) and has used appropriate procedures (e.g. care must be taken with unsteady-state floods if the CO2 and brine are not properly equilibrated as saturation changes can occur through dissolution) in order to judge the quality of the final relperms.

Hopefully this acts as a useful starting off point – all the best pulling your dataset together.