OIL RECOVERY METHOD

A method for selecting an aqueous displacement fluid comprising an aqueous solution of dissolved phosphate species includes obtaining reservoir parameters for a reservoir, receiving an input comprising a permitted loss of dissolved phosphate species resulting from mixing of the aqueous displacement fluid and resident water following injection of a selected pore volume of the aqueous displacement fluid, selecting an aqueous displacement fluid, and determining that a composition of the aqueous displacement fluid is within an operating envelope using the reservoir parameters and the permitted loss of dissolved phosphate species. The reservoir parameters include physical characteristics of the reservoir and chemical characteristics of the resident water. The operating envelope defines boundary conditions for one or more parameters of the composition of the aqueous displacement fluid to limit a loss of dissolved phosphate species upon injection into the reservoir to less than or equal to the permitted loss.