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1. A composition based on anionic polymers or water-soluble amphoteric (co)polymers, wherein the composition is suitable for viscosifying injection fluids for enhanced oil recovery and contains at least 30% by weight of a polymer, and at least three stabilizing agents selected from the group consisting of oxygen reducing agents, precipitating agents, free radical scavengers, complexing agents, and sacrificial agents, the stabilizing agents being suitable for preventing the chemical degradation of the polymer once the polymer is introduced into the injection fluid,
wherein the polymer used contains:
a) at least one monomer selected from non-ionic monomers based on an acrylamide, acrylic, vinyl, allyl or maleic backbone and having a polar non-ionic side group,b) and optionally one or more ionic monomers selected from the group consisting of anionic monomers based on an acrylamide, acrylic, vinyl, allyl or maleic backbone and, having a carboxylic function, a sulphonic acid function; cationic monomers based on acrylamide, acrylic, vinyl, allyl or maleic having an amine or quaternary ammonium function, optionally combined withc) a hydrophobic monomer based on an acrylamide, acrylic, vinyl, allyl or maleic backbone, having a side hydrophobic function selected from the group consisting of derivatives of acrylamide, N,N-dialkylacrylamides, derivatives of acrylic acid, and vinyl monomers,d) and a branching/crosslinking agent selected from the group consisting of methylene bisacrylamide (MBA), ethylene glycol diacrylate, polyethylene glycol dimethacrylate, diacrylamide, cyanomethylacrylate, vinyloxyethylacrylate and methacrylate, triallylamine, formaldehyde, glyoxal, compounds of the glycidylether type and epoxides,e) and a surfactant monomer based on an acrylamide, acrylic, vinyl, allyl or maleic backbone and, having a structure bearing both hydrophilic and hydrophobic functions, and wherein:
the free radical scavengers are selected from the group consisting of diethyl thiourea, dimethyl thiourea, mercaptobenzothiazole and mercaptobenzoimidazole;the oxygen reducing agents are selected from the group consisting of sulphites bisulphites, metabisulphites, dithionite, hydrazine and derivatives thereof, carbohydrazides, and sodium erythorbate;the sacrificial agents are selected from the group consisting of glycerol, propylene glycol, trimethyleneglycol, isopropanol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2,4-butanetriol, pentaerythritol (PETA), trimethylolethane, neopentylglycol, 1,2-pentanediol, 2,4-pentanediol, 2,3-pentanediol, trimethylolpropane, 1,5-pentanediol, and polyvinyl alcohol partially or totally hydrolyzed;the complexing agents are selected from the group consisting of polyacetates, polycarboxylates, polyaspartates, polyphosphates, polyphosphonates, polysuccinates, ethylene-diamine-tetraacetic acid (EDTA), Hepta sodium salt of diethylene triamine penta (methylene phosphonic acid) (DTPMP.Na7), maleic acid, nitrilotriacetic acid (NTA), and oxalic acid; andthe precipitating agents are selected from the group comprising hydroxides, carboxylates, carbonates, arsenates, cyanurates, phosphorus derivatives and sulphur derivatives, and wherein the composition is in the form of a powder, a bead, or a reverse emulsion. |
