1. A method of simulating fluid flow in a subterranean structure containing fracture corridors, comprising: representing the subterranean structure using a model, wherein the model includes a first grid and a second grid, wherein the first grid includes background geological information of the subterranean structure, and wherein the second grid includes the fracture corridors, and wherein the first and second grids are combined to form a simulation grid; and performing, by a processor, a streamline simulation using the model.