Addition of nonionic surfactants to water soluble block copolymers to increase the stability of the copolymer in aqueous solutions containing salt and/or surfactants
View Patent ↗An aqueous fluid useful for the recovery of crude oil from a subterranean formation, which includes a composition including a mixture of water, a water soluble block copolymer, an inorganic salt and at least one member of the group of a nonionic surfactant having an HLB of less than 12, and methods for using same.
1. An aqueous solution composition comprising a mixture of:
water,
about 0.05 to 10 weight % on a wet basis at least one water soluble block copolymer water-soluble in nature and containing hydrophobic units and at least one block predominantly hydrophobic in nature,
about 0.01 to 10 weight % on a wet basis a nonionic surfactant having a hydrophilic-lipophilic balance of less than 12, and
about 0.1 to 20 weight % on a wet basis at least one inorganic salt selected from the group consisting of mono-valent ions, di-valent ions and tri-valent ions.
2. The composition according to claim 1 , wherein the predominantly hydrophobic block has hydrophilic units in an amount equal to between 0 and less than 33% by weight, with respect to the total weight of the units of the hydrophobic block.
3. The composition according to claim 1 , wherein the block polymer water-soluble in nature has hydrophobic units in an amount of less than 70% by weight with respect to the total weight of the units of the block water-soluble in nature.
4. The composition according to claim 1 , wherein the block predominantly hydrophobic in nature comes from the polymerization of a monomer mixture containing at least 80% by weight styrene.
5. The composition according to claim 1 , wherein the mass ratio of the blocks predominantly hydrophilic in nature to the blocks predominantly hydrophobic in nature is between 95/5 and 20/80.
6. The composition according to claim 1 , wherein the copolymer is at a concentration of between 0.1% and 10% by weight.
7. The composition according to claim 1 , wherein the nonionic surfactant has a hydrophilic-lipophilic balance of 2 to 10.
8. The composition according to claim 1 , wherein the nonionic surfactant is at a concentration of between 0.06% and 5% by weight.
9. The composition according to claim 1 , wherein the nonionic surfactant is selected from the group consisting of:
polyethylene oxide condensates of alkyl phenols,
condensation products from the condensation of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylene diamine products,
condensation products of aliphatic alcohols having from about 8 to about 18 carbon atoms,
long chain tertiary amine oxides corresponding to the following general formula I:
R 1 R 2 R 3 N→0 I
wherein R 1 contains an alkyl, alkenyl or monohydroxy alkyl radical of from about 8 to about 18 carbon atoms, from 0 to about 10 ethylene oxide moieties, and from 0 to about 1 glyceryl moiety, and R 2 and R 3 contain from about 1 to about 3 carbon atoms and from 0 to about 1 hydroxy group, e.g., methyl, ethyl, propyl, hydroxyethyl, or hydroxypropyl radicals;
long chain tertiary phosphine oxides corresponding to the following general formula II:
RR′R″P→0 II
wherein R contains an alkyl, alkenyl or monohydroxyalkyl radical ranging from about 8 to about 18 carbon atoms in chain length, from 0 to about 10 ethylene oxide moieties and from 0 to about 1 glyceryl moiety and R′ and R″ are each alkyl or monohydroxyalkyl groups containing from about 1 to about 3 carbon atoms;
long chain dialkyl sulfoxides containing one short chain alkyl or hydroxy alkyl radical of from about 1 to about 3 carbon atoms (usually methyl) and one long hydrophobic chain which include alkyl, alkenyl, hydroxy alkyl, or keto alkyl radicals containing from about 8 to about 20 carbon atoms, from 0 to about 10 ethylene oxide moieties and from 0 to about 1 glyceryl moiety; and
mixtures thereof.
10. The composition according to claim 1 , wherein the nonionic surfactant is selected from the group consisting of octylphenol ethoxylates, nonylphenol ethyoxylates, dodecyl phenol ethoxylates, dinonyl phenol ethoxylates, tristyrylphenol ethoxylates, isotridecyl alcohol ethoxylates, oleyl alcohol ethoxylates, mercaptan ethoxylates, sorbitol esters, ethoxylated sorbitol esters, polyethylene glycol (PEG) esters, PEG phosphate esters, ethocylated acids, alcohol esters, glycerol esters, glycol esters, diethanolamides, monoethanolamdies, alabolamides and mixtures thereof.
11. The composition according to claim 1 , wherein the composition comprises brine.
12. The composition according to claim 1 , wherein the aqueous solution composition is a gel.
13. A hydraulic fracturing fluid comprising the aqueous solution composition of claim 1 , and a proppant.
14. A method for recovering hydrocarbons from a subterranean formation, comprising introducing to the formation an aqueous fluid comprising the composition of claim 1 .
15. A method to create fissures into a subterranean formation which surrounds a well bore, comprising the step of injecting into the bore a fracturing fluid comprising a composition as defined in claim 1 .