Method for controlling the migration of formation fines

A method for averting and/or delaying and/or limiting and/or preventing the migration of fines in a geological formation, said method comprising bringing the formation into contact with one or more copolymers comprising:

• at most 40 mol % of monomeric units derived from one or more cationic monomers of formula (Ia) and/or (Ib)
• CH2═C(R4)—C(═O)—Y—(CH2)m—W(R1)(R2)(R3), X− (Ia)
• [CH2═CH—CH2]n—N+(R1)(R2)(R3)(2−n), X− (Ib)
• in which
• R4 represents a hydrogen atom or a methyl radical,
• R1, R2 and R3, which may be identical or different, represent an ethyl radical or a methyl radical,
• m represents an integer between 1 and 4,
• n represents 1 or 2,
• Y represents O, and
• X− represents an anion chosen from bromide or chloride ions,
• at least 60 mol % of monomeric units derived from one or more neutral monomers of formula (II)
• CH2═C(R5)—C(═O)—N(R6)(R7) (II)
• in which
• R5 represents a hydrogen atom or a methyl radical,
• R6 and R7 represent, independently of one another, a hydrogen atom or an alkyl radical comprising from 1 to 4 carbon atoms, which is optionally substituted with a hydroxyl group,
• wherein the sum of the repeating units derived from the cationic monomer of formula (Ia) and/or (Ib) and the repeating units derived from the neutral monomer of formula (II) represents at least 95 mol % of the total sum of the repeating units of the copolymer, and the copolymer does not comprise organosilane units,
• wherein the copolymer has an average molar mass ranging from 3×106 g·mol−1 to 12× 106 g·mol−1, and
• wherein the method does not comprise injecting of acidic compounds into the geological formation, and
• wherein the copolymers are in a carrier fluid that does not comprise at least one of methanol, ethanol and isopropanol.

A method for averting and/or delaying and/or limiting and/or preventing the migration of fines in a geological formation, said method comprising bringing the formation into contact with one or more non-crosslinked copolymers comprising:

• at most 40 mol % of monomeric units derived from one or more cationic monomers of formula (Ia) and/or (Ib)
• CH2═C(R4)—C(═O)—Y—(CH2)m—W(R1)(R2)(R3), X− (Ia)
• [CH2═CH—CH2]n—N+(R1)(R2)(R3)(2−n), X− (Ib)
• in which
• R4 represents a hydrogen atom or a methyl radical,
• R1, R2 and R3, which may be identical or different, represent an ethyl radical or a methyl radical,
• m represents an integer between 1 and 4,
• n represents 1 or 2,
• Y represents O, and
• X− represents an anion chosen from bromide or chloride ions,
• at least 60 mol % of monomeric units derived from one or more neutral monomers of formula (II)
• CH2═C(R5)—C(═O)—N(R6)(R7) (II)
• in which
• R5 represents a hydrogen atom or a methyl radical,
• R6 and R7 represent, independently of one another, a hydrogen atom or an alkyl radical comprising from 1 to 4 carbon atoms, which is optionally substituted with a hydroxyl group,
• wherein the sum of the repeating units derived from the cationic monomer of formula (Ia) and/or (Ib) and the repeating units derived from the neutral monomer of formula (II) represents at least 95 mol % of the total sum of the repeating units of the copolymer, and the copolymer does not comprise organosilane units,
• wherein the copolymer is solubilized at a concentration of 1000-4000 ppm in 1% KCl,
• wherein the copolymer is provided in a powder form having a particle size within the range of 250 microns to 1 mm,
• wherein the copolymer has an average molar mass ranging from 3×106 g·mol−1 to 12×106 g·mol−1, and
• wherein the method does not comprise injecting acidic compounds into the geological formation.