A machine for simulating a production characteristic for a plurality of oil or gas wells defined by a grid of a reservoir, the machine comprising: a plurality of separate application servers having one or more processors and memory with computer readable instructions stored thereon, the plurality of application servers each being assigned one or more sub-domains of the grid and including computer programs, operable by the one or more processors, for performing a process of re-ordering a local cell identification reference for each of a plurality of cells associated with the one or more sub-domains using characteristics of the cell and location within the one or more sub-domain, the plurality of cells having faces that are formed equidistant to each of a plurality of points corresponding to a geological characteristic of a subsurface, and a process of simulating at least one production characteristic of the reservoir; the computer readable instructions, operable by the one or more processors, for: creating an initial local cell identification reference for each of the plurality of cells in the sub-domain, each local cell identification reference being mapped to an original index assigned to each of the plurality of cells, calculating transmissibility between each of the plurality of cells in the sub-domain using grid data, well data and permeability data read into the memory of the plurality of separate application servers responsive to the initial local cell identification reference, determining one or more other sub-domains adjacent the one or more sub-domains, and which of the plurality of grid cells share at least one face with grid cells of the one or more other sub-domains, re-indexing each of the plurality of grid cells according to whether the grid cell shares at least one face with grid cells of the one or more other sub-domains, re-indexing each of the plurality of grid cells according to the transmissibility of each of the plurality of grid cells, and transmitting simulation data between the grid cells sharing at least one face with the one or more other sub-domains adjacent the sub-domain with the one other sub-domain. creating an initial local cell identification reference for each of the plurality of cells in the sub-domain, each local cell identification reference being mapped to an original index assigned to each of the plurality of cells, calculating transmissibility between each of the plurality of cells in the sub-domain using grid data, well data and permeability data read into the memory of the plurality of separate application servers responsive to the initial local cell identification reference, determining one or more other sub-domains adjacent the one or more sub-domains, and which of the plurality of grid cells share at least one face with grid cells of the one or more other sub-domains, re-indexing each of the plurality of grid cells according to whether the grid cell shares at least one face with grid cells of the one or more other sub-domains, re-indexing each of the plurality of grid cells according to the transmissibility of each of the plurality of grid cells, and transmitting simulation data between the grid cells sharing at least one face with the one or more other sub-domains adjacent the sub-domain with the one other sub-domain.