Generally, hydrocarbon formation will collapse if the pressure in the openhole section is more than the formation breakdown or fracture pressure. Therefore, the first step is to determine the break down pressure or fracture initiation pressure of the formation you intend to use for the lab tests. Formation fracture pressure mainly depends on the compressive stress associated with the formation rock and the strength of the formation itself. When the applied pressure exceeds both the compressive stress and formation strength the formation will break. 

In addition, you can't use any formation containing clay materials for your tests because the presence of water will lead to clay swelling unless you have chemicals/additives to inhibit clay swelling.

Thanks you for your answer but I still need a formation sketch of a lab. model that can use hot water which is cost effective

I would advise you to use CMG STARS Computer model, which has options for these calculations.

shear failure (collapse) may occur at low pore pressure for typical geomechanical environment. To model heat transfer you most likely need CMG STARS. You may also consider tNav (http://rfdyn.com/tnavigator/tnavigator-modules/thermal-compositional-simulator/).

For failure model you may use near wellbore analytical solutions for sanding in 1D/2D.

Dear M. Grzegorz,

I noticed you asked a question few hours ago about the number of if then rules in a fuzzy logic system. I see that you got the answer, so the possible combination of your inputs is the multiplication of the number of the number of MFs. eg. if you have 8 inputs, eah one have 3 MFs so the possible combination is = 3*3*3*3*3*3*3*3=3^8, if one of the has less or more MFs, you have to act accordingly.

But the problem is : should we consider all the possible combinations or just we have to add rules as much as possible by respecting the relashionsip between inputs?

I asked this question and I didn't get ay answer yet. once I get a solution of that I will let you know..

Wish you a lot of courage..