question about wettability and relative permeability

[hdashti]

are there any equation to find relation between wettability and relative permeability?

[mid]

Not really, but if you have an idea on the reservoir wettability you may be able to estimate end points and cross over just as guidance, but the need for SCAL measurements is needed, nowadays there is a new industry potential using neural network (ecore) this is now being developed and when it works you will be able to model relative permeability and any production profile using thin section slide and neural net work model

[macwalker44]

hi mid,can U help me with Ecrin software.I want to do some analysis.I appericiate

[jack]

can somebody provide literature or anything on how to generate relative permeability curves through SCAL data,any software for this.i will be very grateful to you
regards
jack

[Yegor]

I think that relative permeability don’t depend of wettability. Probably, these properties depend of pore's geometry (theory of fractal structure reservoir)

[bonz_gutguy]

i have many question of wettability,,
1) can you explain me about what the function of wettability in oil&gas field (influence/effect wettability)?
2) in college, i know the kind of wettability is water-wet, oil-wet, or neutral-wet but i find fractural-wet + mixed wet,, can you explain me about that?

thank you,,

[vinomarky]

Think of a highly polished car vs a very dirty car.

When you sprinkle water on a polished car, the water tends to bead up into balls and run off it very quickly/easily - gravity forces easily move the water. In this case the car surface is oil wet, meaning oil will preferentially coat the surface rather than water

If you took the car out on a dirt track for a week and left it to dry, then sprinkled water in it then the whole car would turn muddy - the water is being absorbed onto the mud surface rather than running off. If you were to dribble some light oil on the wet/muddy surface it would tend to run off rather than adhere. Here, the car surface has changed to water wet

So what does this mean for our reservoirs?

Well, if the reservoir is water to mixed wet (most clastics), then the irreducible fluid will be water and oil/gas will preferentially flow through it

Conversely, if the reservoir is oil to mixed wet, then the irreducible fluid will be oil and water will preferentially flow through it

To Yegor above who states that wettability does not affect rel perm, that is just wrong. For a given water saturation if the rock is water wet then water will have a lower rel perm than if it were oil wet.

[DAH7542]

I would like to add some comments on this subject, specifically regarding bonz_gutguy's question and Yegor's comment:

1. Wettability does control relative permeability, since wettability controls the relative position of fluids within the rock matrix, it controls their ability to flow (comment taken from Cobb's course notes of waterflooding).
2. There is a difference between the concepts of "Mixed or Fractional Wettability" and "Intermediate or Neutral Wettability", Anderson makes it clear, some definitions are:

- Oil or Water wet: pretty clear so far, refer to Vinomarky's comments.

- Fractional wettability: also called spotted, Dalmation or heterogeneus wettability. In this sort of wettability the rock has a variety of preferences, some parts may be oil-wet, others water-wet or neutral. This makes sense when we realize that rocks are composed of several minerals, each one with different surface chemistry. "Mixed Wettability", according to Anderson, is some sort of Fractional Wettability in which oil-wet surfaces form continuous paths through the larger pores; some other papers, like the one below by Schlumberger, generalize that Mixed Wetability is the same as Fractional Wettability.

- Intermediate Wettability: also called neutral wettability, when the rock has no strong preference for either oil or water.

I recommend the following reading:

Fundamentals of Wettability; Schlumberger, Oilfield Review

[link Point to another website Only the registered members can access]
Anderson, W. Wettability literature survey - Part 1. Available at SPE One Petro.