Patent ID: 8022016

Claim:
A viscoelastic fluid, comprising: one or more cationic surfactants; one or more anionic polymers; one or more zwitterionic surfactants and/or one or more amphoteric surfactants; and water; wherein the one or more cationic surfactants is selected from the group consisting of i) quaternary salts having the following structural formula: R 1 is a hydrophobic moiety of alkyl, alkylarylalkyl, alkoxyalkyl, alkylaminoalkyl or alkylamidoalkyl, wherein R 1 has from about 18 to about 30 carbon atoms and may be branched or straight-chained and saturated or unsaturated; R 2 , R 3 , and R 5 are, independently, selected from the group consisting of an aliphatic moiety having from 1 to about 30 carbon atoms and an aromatic moiety having from 7 to about 30 carbon atoms; the aliphatic moiety being branched or straight-chained and saturated or unsaturated; wherein X is a counter-anion; ii) amines having the following structural formula: wherein R 1 , R 2 and R 3 are the same as defined above; iii) amine oxides having the following structural formula: wherein R 1 , R 2 and R 3 are as defined above; and iv) combinations thereof; wherein the one or more zwitterionic surfactants has the following structural formula: wherein R 1 , R 2 , and R 3 are as described above; R 4 is a hydrocarbyl radical with a chain length 1 to 4; and wherein the one or more amphoteric surfactants has the following structural formula: wherein R 1 , R 2 , and R 4 are as described above.