Abstract: One or more computer-readable media include computer-executable instructions to instruct a computing system to iteratively solve a system of equations that model a wellbore and fracture network in a reservoir where the system of equations includes equations for multiphase flow in a porous medium, equations for multiphase flow between a fracture and a wellbore, and equations for multiphase flow between a formation of a reservoir and a fracture. Various other apparatuses, systems, methods, etc., are also disclosed.

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.

Abstract: One or more computer-readable media include computer-executable instructions to instruct a computing system to iteratively solve a system of equations that model a wellbore and fracture network in a reservoir where the system of equations includes equations for multiphase flow in a porous medium, equations for multiphase flow between a fracture and a wellbore, and equations for multiphase flow between a formation of a reservoir and a fracture. Various other apparatuses, systems, methods, etc., are also disclosed.

Abstract: One or more computer-readable media include computer-executable instructions to instruct a computing system to iteratively solve a system of equations that model a wellbore and fracture network in a reservoir where the system of equations includes equations for multiphase flow in a porous medium, equations for multiphase flow between a fracture and a wellbore, and equations for multiphase flow between a formation of a reservoir and a fracture. Various other apparatuses, systems, methods, etc., are also disclosed.

Abstract: A method can include providing a system of equations with associated variables that describe physical phenomena associated with a geologic formation; decoupling the system of equations to provide a system of pressure equations with associated pressure variables; solving the system of pressure equations for values of the pressure variables; and, based at least in part on the values of the pressure variables, solving the system of equations for values of the associated variables where the solving the system of equations includes applying a block approximate inverse preconditioner technique to at least blocks of mass conservation terms of the system of equations. Various other apparatuses, systems, methods, etc., are also disclosed.

Abstract: The present disclosure relates to a method to improve the performance of reservoir simulators, and to widen the range of systems that can efficiently be modeled. The present disclosure relates to determining fluid flow in a subsurface reservoir. One embodiment divides the reservoir into discrete volume elements. Fluid within the volume elements is represented, for example, by it pressure, saturation, and/or composition. For one or more fluid phases comprising the fluid, the potential for each volume element is determined. The volume elements are ordered according to their potentials for each phase comprising the fluid. A local, fully coupled time-step sequence is determined using a local conservation solution based on the potential ordering of and for each fluid phase. The fluid flow is determined using a global conservation solution based on the local, fully coupled time-step sequence.

Abstract: One or more computer-readable media include computer-executable instructions to instruct a computing system to iteratively solve a system of equations that model a wellbore and fracture network in a reservoir where the system of equations includes equations for multiphase flow in a porous medium, equations for multiphase flow between a fracture and a wellbore, and equations for multiphase flow between a formation of a reservoir and a fracture. Various other apparatuses, systems, methods, etc., are also disclosed.

Abstract: The present disclosure relates to a method to improve the performance of reservoir simulators, and to widen the range of systems that can efficiently be modeled. The present disclosure relates to determining fluid flow in a subsurface reservoir. One embodiment divides the reservoir into discrete volume elements. Fluid within the volume elements is represented, for example, by it pressure, saturation, and/or composition. For one or more fluid phases comprising the fluid, the potential for each volume element is determined. The volume elements are ordered according to their potentials for each phase comprising the fluid. A local, fully coupled time-step sequence is determined using a local conservation solution based on the potential ordering of and for each fluid phase. The fluid flow is determined using a global conservation solution based on the local, fully coupled time-step sequence.