Abstract: A methodology for modeling oil/water or gas/water paleo zone reservoir properties for hydrocarbon management is provided. Reservoir simulations in a subsurface, such as in an oil region bounded by a gas cap and a water region, may use an initial reservoir simulation model. The methodology determines one or both of the oil/water or gas/water interfaces to honor the equilibrium state of the subsurface. The current configuration of the subsurface may be the result of one or more processes, such as a drainage process and an imbibition process, each of which have different associated curves reflecting the physical phenomena of the fluid/rock properties in the subsurface. The methodology honors the physical process, including comporting with the different curves and with the available data, in order to determine the current state of the subsurface, including one or both of the oil/water or gas/water interfaces.

Abstract: A method of performing a simulation of a subsurface hydrocarbon reservoir. The reservoir is approximated by a reservoir model having a plurality of cells. Each cell has an equation set representing a reservoir property. An initial guess is provided to a solution for a system of equations formed using the equation set for each of the cells. An iterative root-finding method and the initial guess are used to solve for a solution to the system of equations. When the number of non-converged cells is greater than a predetermined amount, neighboring converged cells are added to the non-converged cells. Parts of the method are repeated, substituting the solved solution for the initial guess and the equation sets corresponding to the non-converged cells for the first system of equations, until substantially all equation sets satisfy the convergence criterion. The solved solution is outputted as a simulation of the subsurface reservoir.

Abstract: A method for performing a simulation of a subsurface hydrocarbon reservoir is disclosed. Each cell in a reservoir model has an equation set representing a reservoir property. A stability limit is determined for each cell. Each cell is assigned to an explicit or implicit formulation. A solution to the system of equations is solved for using an initial guess and an explicit or implicit formulation. A stability limit is calculated for the converged cells. When the number of unconverged cells is greater than a predetermined amount, a reduced nonlinear system is constructed with a list of unconverged cells. The reduced nonlinear system is solved with the implicit formulation, and other cells are solved with the explicit formulation. Parts of the method are repeated until all equation sets satisfy a convergence criterion and a stability criterion, and the solved solution is output.

Abstract: A method for performing a simulation of a subsurface hydrocarbon reservoir is disclosed. Each cell in a reservoir model has an equation set representing a reservoir property. A stability limit is determined for each cell. Each cell is assigned to an explicit or implicit formulation. A solution to the system of equations is solved for using an initial guess and an explicit or implicit formulation. A stability limit is calculated for the converged cells. When the number of unconverged cells is greater than a predetermined amount, a reduced nonlinear system is constructed with a list of unconverged cells. The reduced nonlinear system is solved with the implicit formulation, and other cells are solved with the explicit formulation. Parts of the method are repeated until all equation sets satisfy a convergence criterion and a stability criterion, and the solved solution is output.

Abstract: A method of performing a simulation of a subsurface hydrocarbon reservoir. The reservoir is approximated by a reservoir model having a plurality of cells. Each cell has an equation set representing a reservoir property. An initial guess is provided to a solution for a system of equations formed using the equation set for each of the cells. An iterative root-finding method and the initial guess are used to solve for a solution to the system of equations. When the number of non-converged cells is greater than a predetermined amount, neighboring converged cells are added to the non-converged cells. Parts of the method are repeated, substituting the solved solution for the initial guess and the equation sets corresponding to the non-converged cells for the first system of equations, until substantially all equation sets satisfy the convergence criterion. The solved solution is outputted as a simulation of the subsurface reservoir.

Abstract: A field operating policy for a subsurface region is optimized by setting initial policy parameters for the subsurface region. Fluid flow within a subsurface region is simulated, wherein the simulation includes optimizing an objective function for field operating policy, the objective function corresponding simultaneously to the modeled fluid flow characteristics of one or more wellbores within the subsurface region and relating to at least one production system performance parameter. Optimizing the objective function for field operating policy may include optimizing the initial policy parameters for the subsurface region with an over time optimization technique, wherein the policy parameters are optimized for a predetermined policy period. An enhanced value of the objective function is determined at each timestep within the predetermined policy period.