A process for mineral oil production, in which an aqueous formulation comprising at least one water-soluble, hydrophobically associating copolymer is injected through at least one injection borehole into a mineral oil deposit, and crude oil is withdrawn from the deposit through at least one production borehole, wherein
- the water-soluble, hydrophobically associating copolymer comprises
- (a) 0.1to 15% by weight of at least one monoethylenically unsaturated, hydrophobically associating monomer (a) selected from the group of
- H2C═C(R1)—R2—O—(—CH2—CH(R3)—O—)k—(—CH2—CH(R4)—O—)l—R5 (I),
- H2C═C(R1)—O—(—CH2—CH(R3)—O—)k—R6 (II),
- H2C═C(R1)—(C═O)—O—(—CH2—CH(R3)—O—)k—R6 (III),
- where the —(—CH2—CH(R3)—O—)k and —(CH2—CH(R4)—O—)1units are arranged in block structure in the sequence shown in formula (I) and the radicals and indices are each defined as follows:
- k:
- a number from 15to 30,
- l:
- a number from 5to 25,
- R1:
- H or methyl,
- R2:
- a single bond or a divalent linking group selected from the group of —(CnH2n)—[R2a], —O—(Cn′H2n′)—[R2b] and —C(O)—O—(Cn″H2n″)—[R2c], where n, n′ and n″ are each natural numbers from 1 to 6,
- R3:
- each independently H, methyl or ethyl, with the proviso that at least 50mol% of the R2 radicals are H,
- R4:
- each independently a hydrocarbyl radical having at least 2 carbon atoms or an ether group of the general formula —CH2—O—R4′, where R4′ is a hydrocarbyl radical having at least 2carbon atoms,
- R5:
- H or a hydrocarbyl radical having 1to 30carbon atoms,
- R6:
- an aliphatic and/or aromatic, straight-chain or branched hydrocarbyl radical having 8to 40carbon atoms,
- and also
- (b) 85to 99.9% by weight of at least two monoethylenically unsaturated, hydrophilic monomers (b) different than (a), where the monomers (b) comprise
- (b1) at least one uncharged, monoethylenically unsaturated, hydrophilic monomer (b1), selected from the group of (meth)acrylamide, N-methyl(meth)acrylamide, N,N′-dimethyl(meth)acrylamide or N-methylol(meth)acrylamide, and
- (b2) at least one anionic, monoethylenically unsaturated, hydrophilic monomer (b2) which at least one acidic group selected from the group of —COOH, —SO3H and —PO3H2 and salts thereof, wherein at least one monomer comprising —SO3H groups or a salt thereof is present,
- wherein the uncharged monomers (b1) are used in an amount of 30to 95% by weight and the anionic monomers (b2) in an amount of 4.9to 69.9% by weight, where the proportions are each based on the total amount of all monomers in the copolymer,
- the copolymer has a weight-average molecular weight Mw of 1*106 g/mol to 30*106 g/mol,
- the amount of the copolymer in the formulation is 0.02 to 2% by weight, and
- the temperature of the mineral oil deposit is 40 to 90° C.