Patent ID: 8794327

Claim:
An enhanced oil recovery method using injection of aqueous polymer solutions into reservoir rock, comprising the following stages: a) injecting a first aqueous solution of non-associative hydrophilic polymers into a reservoir in a predetermined proportion so that they adsorb on the reservoir rock, the injection of the non-associative polymer into the reservoir creating a first layer comprising the non-associative polymers, the non-associative polymers of said first layer having a molar mass ranging between 20.10 3 and 40.10 6 g/mol; and then b) injecting a second aqueous solution of associative polymers into the reservoir for oil recovery, with limited adsorption considering the adsorption of said non-associative polymers of said first solution, the injection of the associative polymers into the reservoir creating a second layer comprising the associative polymers, the associative polymers of said second layer having a molar mass ranging between 20.10 3 and 20.10 6 g/mol.