1. A machine adapted to supply 2.5 dimension simulations, the machine comprising: a first computer server associated with a data pre-processor defining a pre-processing server, the pre-processing server having a processor and non-transitory memory and being adapted to send and receive data; a second computer server associated with computer storage and defining a file server; the file server having non-transitory file server memory and being adapted to send and receive data; and a computer program product stored on the memory and including instructions that when executed by the processor cause the pre-processing server to perform a process of generating a grid and a process of encoding the grid to be stored on the file server, the instructions comprising the steps of: projecting static properties of the reservoir, including external and internal boundaries, onto a top surface of a future grid, constructing a 2D unstructured grid along the top surface of the future grid using static properties of the reservoir, the 2D unstructured grid having cells and the cells having vertexes defining the cell boundaries, reconstructing the 2D unstructured grid along a bottom surface of the future grid; constructing a vertical line the thickness of the reservoir through the future grid, to join the corresponding vertexes in the 2D unstructured grids on the top and bottom surfaces; creating markers along the vertical line, the markers corresponding to each layer in the reservoir and being defined using a location of each layer's horizon; duplicating vertexes on the top and bottom layers when a vertical fault line is to be modeled, the duplicated vertexes generating parallel vertical lines, and the parallel vertical lines having different markers thereon; copying the 2D, unstructured grid created for the top layer to each reservoir layer, the 2D unstructured grid being located at each marker to thereby create a 2.5 D grid; and assigning each grid cell vertex and each grid cell an index and storing each grid cell and grid cell index in memory using compressed spare row format.