A computer-implemented method for simulating and managing a chemical enhanced oil recovery process, the method comprising: receiving a geological model of a subsurface reservoir where a chemical enhanced oil recovery process is to be performed, the geological model segmenting the subsurface reservoir into a grid having a plurality of cells and defining a volume of surfactant, a volume of water and a volume of oil within each of the plurality of cells; using the model to simulate the chemical enhanced oil recovery process by, at a plurality of sequential times: determining a surfactant concentration for each cell based on the volume of surfactant and the volume of water within each of the plurality of cells and independently from the volume of oil within each of the plurality of cells; simulating fluids flowing in the subsurface reservoir by modeling introduction of water and surfactant and modeling flow of all fluids within the reservoir based on the determined surfactant concentration; and predicting production rates of fluid based on the simulation of fluid flow; and based on the simulation: optimizing the simulated chemical enhanced oil recovery process by adjusting one or more parameters of the simulation; or determining one or more operational parameters for an oil recovery system, the oil recovery system being for performing the chemical enhanced oil recovery process, for provision to the oil recovery system to manage the chemical enhanced oil recovery process. receiving a geological model of a subsurface reservoir where a chemical enhanced oil recovery process is to be performed, the geological model segmenting the subsurface reservoir into a grid having a plurality of cells and defining a volume of surfactant, a volume of water and a volume of oil within each of the plurality of cells; using the model to simulate the chemical enhanced oil recovery process by, at a plurality of sequential times: determining a surfactant concentration for each cell based on the volume of surfactant and the volume of water within each of the plurality of cells and independently from the volume of oil within each of the plurality of cells; simulating fluids flowing in the subsurface reservoir by modeling introduction of water and surfactant and modeling flow of all fluids within the reservoir based on the determined surfactant concentration; and predicting production rates of fluid based on the simulation of fluid flow; and based on the simulation: optimizing the simulated chemical enhanced oil recovery process by adjusting one or more parameters of the simulation; or determining one or more operational parameters for an oil recovery system, the oil recovery system being for performing the chemical enhanced oil recovery process, for provision to the oil recovery system to manage the chemical enhanced oil recovery process. determining a surfactant concentration for each cell based on the volume of surfactant and the volume of water within each of the plurality of cells and independently from the volume of oil within each of the plurality of cells; simulating fluids flowing in the subsurface reservoir by modeling introduction of water and surfactant and modeling flow of all fluids within the reservoir based on the determined surfactant concentration; and predicting production rates of fluid based on the simulation of fluid flow; and based on the simulation: optimizing the simulated chemical enhanced oil recovery process by adjusting one or more parameters of the simulation; or determining one or more operational parameters for an oil recovery system, the oil recovery system being for performing the chemical enhanced oil recovery process, for provision to the oil recovery system to manage the chemical enhanced oil recovery process. optimizing the simulated chemical enhanced oil recovery process by adjusting one or more parameters of the simulation; or determining one or more operational parameters for an oil recovery system, the oil recovery system being for performing the chemical enhanced oil recovery process, for provision to the oil recovery system to manage the chemical enhanced oil recovery process.