There appears to be a worrying problem arising from the use of pinch cells within Petrasim 5. As our own in-house development team had a bit of trouble getting pinch cells to produce consistent results, we were very excited to see that Petrasim allows pinched cells to be included within TOUGH2 models. However, when we build a simple pinch cell test model, it appears that the pressure gradients accross the domain are distorted by the presence of pinch cells.
Our test model:
3m x 3m domain (x,z)
8 cells - see attached page for grid geometry and results.
Boundary conditions - both sides of model are infinite volume (1E40 in vol.factor box).
Left side inf. vol. cells are increased in pressure.
Right side inf vol pressure is fixed.
The model thus simply calculates the pressure distribution accross the pinch cell and cells above and below.
The model is also isothermal - so no convective control on flow.
What we were hoping for is a linear decrease in pressure accross the domain from left to right.
Instead, we get a very confusing pressure distribution and where we get a sensible pressure gradient, we get flow in the wrong direction...
We are not sure where we are going wrong - hopefully it is us that is causing the problem, and we can continue to be excited with using pinch cells! Any advice would be most appreciated, we include an input file for TOUGH and a brief, not so neat spread sheet that shows the upsetting results.
Problematic pinch cells.htm