Abstract: A method can include identifying a discrete natural fracture in a three-dimensional environment that includes a reservoir modeled by a three-dimensional grid model, representing the discrete natural fracture via a multisegment model in a two-dimensional region within the three-dimensional grid model, defining at least one connection for fluid communication between the multisegment model and the three-dimensional grid model, defining boundary conditions for the multisegment model, and solving the multisegment model subject to the at least one connection and the boundary conditions to provide values for fluid flow in the two-dimensional region. Various other apparatuses, systems, methods, etc., are also disclosed.