• Models for the economical viability of the geochemical flow using PDEs and a functional defined from the PDEs solution. • Analytical and numerical strategy based on theory for conservation laws to solve the general model. • Analytical optimization of the parameters of the functional with the optimization regions for polymers injection. • Introduction of a general technique for the study of economic viability of geochemical flow for different chemical species . In the oil recovery process, it is well-known that adding some types of chemical species (for instance water-soluble polymer or solvents) into the water injected into porous media can enhance the oil recovery factor for the water flood recovery method. However, the use of such chemical species in the injection process increases the overall cost; not only in regard to the cost of chemical species, but also by increasing the time to reach water breakthrough. To study this behavior, we use a system of partial differential equations that models the flow of water, oil and chemical species (soluble in water or oil) into one-directional porous media filled with oil. For the case that the chemical species is soluble only in water and for suitable initial conditions (of the Riemann type), we prove that the system’s solution projects to a single scalar equation. We use the solution of the scalar equation to define a functional called the profit functional , which allows study of the economic viability of chemical injection. This study presents a simple way to deal with this class of problems in which we dynamically obtain regions to optimize the functional solution that we defined.