of the flows and of the geometry so that their union covers the entire simulation domain and that there is a minimum overlap between two neighboring elementary grids interpolation parameters allowing connection of the flows calculated on the grid to the flows calculated on the neighboring grids are then determined on the border of each elementary grid finally flows are simulated within the reservoir and the well and the variables describing the flow on the border of the overlap zones are interpolated using the interpolation parameters application_number US 44447406 A description according to the invention the method for simulating fluid flows within a reservoir can be broken up into three main stages 1 construction of a chimera grid representing the simulation domain that is the set of the reservoir subdomain and of the subdomain of the discontinuities running through the reservoir 2 definition of interpolation formulas at the level of the overlap zone to provide continuity of the solution on the borders of the subdomains to simplify the description the discontinuities are assumed to be wells which allows to illustrate radial flows being taken into account without limiting the invention to this type of discontinuity a chimera grid is a multi block grid with overlap these grids are a set of elementary grids covering the domain being studied having as only constraints a minimum overlap and similar cell sizes in the overlap zones the main asset of this type of grid lies in the flexibility and the modularity of the definition of the grid of the models and of the numerical methods of each.