Items missing from model (cells and/or faults)

The viewer starts, but why can I only see a few (or no) cells?

First check the cells have been switched on:

Toggle Show Cells option "on" in the ViewGen Edit menu.

Are all (or most) of the cells are inactive?

This can be checked by switching on inactive cells. Click on Edit->Cell Controls...->Cell views-Inactive only, and press Apply. Cells may be inactivated because:-

The Coordinate system was incorrect. This results in cells that have a negative volume as they are inside out. To correct this, change the TGAXES keyword by closing ViewGen, launching WizGen, selecting the relevant layout of the input data on the Coordinate System page and saving the setting to modify the coordinate system.

Less likely causes are:

The MINPV keyword has been set too large and exceeds the net pore volume of most of the cells (see Cell pore volume cutoff setting on the Miscellaneous Options page of WizGen).

Data in the ACTNUM section is incorrect and excludes most of the cells (if the ACTNUM keyword is included in the parent Eclipse model, it should also be included in the TransGen model via the Included Data page of WizGen).

PORO, NTG, or Permeability (eg. PERMX) data have been set to zero in error.

Why are a few cells which I expected to see absent?

Cells may be inactivated for a variety of reasons:

One of the commonest reasons for a few cells to be missing is that they are geometrically invalid. When COORD lines cross, it is possible for the front of a cell to be behind the back of another resulting in a cell that is largely inside out. These cells will be reported in the ViewGen log as having large negative volumes. It is possible to switch on inactive cells only to check their positions and select groups of COORD lines to check if they do indeed cross.

Another cause is that the Coordinate system was incorrect which again results in cells being inside out. Generally large numbers of cells would be missing in this situation. To correct this, change the TGAXES keyword by closing ViewGen, launching WizGen, selecting the relevant layout of the input data on the Coordinate System page and saving the setting to modify the coordinate system.

Other possible causes are:-

The parameters defining the Lower limits for the MINPV or TGVOLERR keywords have been set too large and exceeds the volumes of these of the cells - check the Cell pore volume cutoff and/or Cell volume error tolerance settings on the Miscellaneous Options page of WizGen.

Data in the ACTNUM section is incorrect and some of the cells which should be active have been inactivated.

Some PORO, NTG or permeability data have been set to zero in error, possibly by an incorrect COPY, BOX, or EQUALS keyword.

The viewer starts, but I can see too few (or no) faults?

First check the faults have been switched on:

Toggle the Show faults option "on" in the ViewGen Edit menu and that some Property or Outline Fault Views option has been toggled "on" in the Fault Controls menu.

Check if the cells required to generate the missing faults are inactive:

This can be checked by switching "off" all active cells and switching "on" the inactive cells. Click on Edit->Cell Controls...->Inactive only, and press apply. Cells may be inactivated because:

The Coordinate system was incorrect. This results in cells that have a negative volume as they are inside out. To correct this, change the TGAXES keyword by closing ViewGen, launching WizGen, selecting the relevant layout of the input data on the Coordinate System page and saving the setting to modify the coordinate system.

A Less likely cause is:
The ZCORN data is incorrect and does not contain offsets between grid-block faces.