Hello. I am a student and relatively new to TOUGH2. I am trying to create a model with a series of six boreholes, each containing a u-tube shaped pipe and all the pipes are connected along the surface. I have been trying to create this model with petrasim, but as far as I can tell, wells can bend but it has trouble creating more than one bend in the pipe. Does anyone have any ideas? My other thought would be to create a very fine mesh and edit each cell to be the casing or inside of the pipe. Thank you.
As an alternative, that worked for me, you may also work directly on the TOUGH2 files (it may appear difficult at first, but the results overwhelm by far the initial discourage you may experience) and create an "artificial" well, independent of the grid, that has a reasonable number of elements (cells). Then manually create the connections between the well's cells and the connections between the wells' cells and the grid cells they belong.
You may keep these cells and the connections in the blocks ELEME and CONNE, respectively, in a place that is convenient. I usually keep the cells at the end of the bock ELEME and the connections at the beginning of the block CONNE so that I can find all of them easily and can change whatever I need. You may need to change the volumes of the elements, and the interface area and the distance between nodes and interfaces of the connection according to the dimension of the well relative to that of the cells they are in.
This sort of trick allows you to monitor easily each wells' cell during simulation and to do appropriate corrections. The only thing you have to be careful about is to keep the volume ratios between grid cells and well cells at a reasonable not-too-small value (I usually try not to go smaller than 0.1, but smaller ratios may work as well).
The part you have to be most careful is giving the initial conditions. This must be as close as possible to the real system you are trying to simulate. If TOUGH2 does not converge, it frequently means that your IC are not close enough to real. Start with a very simple grid (few cells) and then evolve from there to a more complex grid. Creating a "fantastic" "perfect" grid at first, most of the times, leads to failure…