Abstract: Improved reservoir simulation methods and systems are provided that employ a new velocity model in conjunction with a sequential implicit (SI) formulation or Sequential Fully Implicit (SF) formulation for solving the discrete form of the system of nonlinear partial differential equations. In embodiments, the new velocity model employs a fluid transport equation part based on calculation of phase velocity for a number of fluid phases that involves capillary pressure and a modification coefficient. In embodiments, the modification coefficient can be based on a derivative of capillary pressure with respect to saturation. In another aspect, the new velocity model can employ an estimate of the phase velocity of the water phase vw_est that is based on one or more derivatives of capillary pressure of the water phase as a function of water saturation.

Abstract: Embodiments of conservative, sequential fully implicit compositional reservoir simulation are disclosed where 1) pressure, 2) saturation, 3) component balance, and 4) phase equilibrium are computed sequentially to solve for movement of liquid and gas phases over a series of time-steps until convergence to represent fluid flow within the subterranean reservoir. All molecular components in each of the liquid and gas phases are fixed to move with an equivalent phase velocity. Thermodynamic fluxes are accounted for when computing phase equilibrium by computing a difference between fluid volume and pore volume. A hybrid upwinding scheme can be employed to reorder cells based on upwind direction to improve the saturation convergence, especially when phase equilibrium significantly alters the cell properties.

Abstract: Improved reservoir simulation methods and systems are provided that employ a new velocity model in conjunction with a sequential implicit (SI) formulation or Sequential Fully Implicit (SF) formulation for solving the discrete form of the system of nonlinear partial differential equations. In embodiments, the new velocity model employs a fluid transport equation part based on calculation of phase velocity for a number of fluid phases that involves capillary pressure and a modification coefficient. In embodiments, the modification coefficient can be based on a derivative of capillary pressure with respect to saturation. In another aspect, the new velocity model can employ an estimate of the phase velocity of the water phase ?w_est that is based on one or more derivatives of capillary pressure of the water phase as a function of water saturation.

Abstract: A projection-based embedded discrete fracture model (pEDFM) method for simulation of flow through subsurface formations. The pEDFM includes independently defining one or more fracture and a matrix grids, identifying cross-media communication points, and adjusting one or more matrix-matrix and a fracture-matrix transmissibilities in a vicinity of a fracture network. The pEDFM allows for accurately modeling the effect of fractures with general conductivity contrasts relative to the matrix, including impermeable flow barriers. This may be achieved by automatically adjusting the matrix transmissibility field, in accordance to the conductivity of neighboring fracture networks, alongside the introduction of additional matrix-fracture connections.