A two-stage process for mineral oil production from mineral oil deposits with a deposit temperature of more than 70° C. and a salinity of 20 000 ppm to 350 000 ppm, in which an aqueous formulation comprising at least one glucan with a β-1,3-glycosidically linked main chain, and side groups β-1,6-glycosidically bonded thereto and having a weight-average molecular weight Mw of 1.5*106 to 25*106 g/mol, are injected into a mineral oil deposit through at least one injection borehole and crude oil is withdrawn from the deposit through at least one production borehole. The aqueous formulation is prepared in two stages, by first preparing an aqueous concentrate of the glucan, and diluting the concentrate on site with water to the use concentration.