View Full Version : Criticism of Eclipse's way of calculating initial equilibrium

05-04-2015, 10:24 AM
I'm a student studying reservoir engineering, and as part of my master thesis I'm supposed to criticize the way Eclipse calculates the initial conditions in the reservoir. Eclipse has several ways to do this, and I guess each way has its pros and cons. The emphasis will be on equilibration, and not on enumeration and restart runs.
Do any of you have some comments or some criticism of the way Eclipse calculates initial conditions? What assumptions does Eclipse make, and what errors do these assumptions lead to, compared to reality?


05-05-2015, 10:28 AM
Hello if you are a student then you need to read ...
All this you are asking is in the eclipse technical describtion
if you do not have this tell me and i will send you materials

05-05-2015, 10:35 AM
Yeah, thanx, I have Eclipse Technical Description available. But will you say that the emphasis should be on the capillary pressure curves?
Does Eclipse work with negative capillary pressures? Does the default method in Eclipse not take wettability variations into account? For instance, often only a primary drainage capillary pressure curve is assigned to the model, and assumed no hysteresis. If something happened in the reservoir before discovery that made the OWC raise (so there exists a paleo contact), how can you obtain equilibrium without hysteresis?

05-05-2015, 12:07 PM
Read the section about initialization.
There a lot otions how you can initialise the eqile
by negative cap pressures you mean hysteris?
just read the manual dijest what you understand in the form of document
and post here for others to read

05-05-2015, 12:20 PM
Yeah, I know there are a lot of options of how to initialize. The default method is by the EQUIL keyword, where saturations are calculated by inverse look-up of the capillary pressure curves assigned in the saturation functions (SWOF/SWFN). My question is really what do you think is unrealistic about this algorithm?
Is it the way the capillary pressure data normally is assigned to a model (normally only capillary primary drainage curve, assuming no hysteresis)? That this does not take into account wetting properties of the reservoir, or the saturation history?
Or what do you think is unrealistic about this approach?

05-07-2015, 10:50 AM
The main thing i dislike is that there are filed where you do not have any presence of water . So the migration of the oil in this fields are not inline with the main theory that first there was a water then oil became and start to displace the water by capillary forces which is a function of density wettability angle and surface tension. But your question is very broad and it ends in the oil bearing mother rocks and open main question - what are the nature of oil is it organic or not organic. I think that you need to emphasize your work on something that then can be implemented in industry rather that stress philosophy. Nothing personal i am an engineer and like to solve problems which then will help others people in there work and i wish you the same. Good luck.

05-07-2015, 07:46 PM
iespe, perhaps you could look onto how reservoirs with tilted contacts initialised, also could be more flexible. But as temr said you can still use this 'not perfect' tool to solve complex problems by making assumptions, simplifying etc...
would be interesting to see your conclusions on hysteresis in eclipse, please consider posting/sharing here!