Can you, please, elaborate more on that?
I do not know about the petroleum industry, but in aeronautics, sometimes simulations running on (hundreds of) thousands of CPUs generate gigantic datasets.
For very large meshes, writing the solution and the mesh to files, and later loading them for the purpose of visualization is not only very slow (I/O dominates the whole process), but is also wasteful. The idea is to connect the simulation with a co-processing framework, like ParaView Catalyst, to display the results and to obtain derived quantities (e.g. slices) on the fly.