Patent EA-005238-B1 (EA)
Title: A novel fluid system having controllable reversible viscosity
Inventor: CHANG FRANK F
IPC: C09K8/86
Filed: 2000-10-11
Abstract: 1. A fluid for stimulating the production of hydrocarbons prepared by combining: (a) a gelling agent having the structure or a protonated/deprotonated homolog or salt thereof; and R is a hydrocarbon chain having 16-26 carbon atoms and can be saturated or unsaturated, straight or branched; wherein n is between 2 and 10, and p is between 1 and 5; (b) a co-surfactant having the structure or a protonated/deprotonated homolog or salt thereof; wherein x is between 5 and 15; and (c) an acid selected from the group consisting of hydrochloric acid, a mixture of hydrofluoric acid and hydrochloric acid, acetic acid, and formic acid. 2. The fluid of Claim 1 wherein m = 18-22, n = 2-5, and p = 1-3. 3. The fluid of Claim 2 wherein said co-surfactant is para-sodium dodecylbenzene sulfonate. 4. The fluid of any one of Claims 1-3 wherein said gelling agent is present in said fluid at a concentration of between 3 and about 5%, by weight, said co-surfactant is present in said fluid at a concentration of between about 0.3 and about 0.5%, by weight, preferably between 0.3-0.4% by weight, and wherein said acid is present in said fluid at a concentration of between about 3% and about 28%, by weight, preferably at about 25%. 5. A novel fluid system having controlled reversible viscosity, comprising a gelling agent of the formula a co-surfactant, and a dissolution agent, wherein said gelling agent is an amphoteric surfactant, having a substantially hydrophobic portion R1 in turn comprised of a hydrocarbon chain of at least about 10 carbon atoms, and a substantially hydrophilic portion N<+>R2R3CnX (Y), wherein R2 and R3 are identical or different and comprise from 1 to 3 carbon atoms, being straight or branched, saturated or unsaturated, or OH groups, and Cn is a hydrocarbon chain having from 1 to 3 carbon atoms, and X is carboxylate, phosphate, phosphonate, sulfonate or sulfate group, wherein said co-surfactant is an organic acid having a hydrophilic portion and a hydrophobic portion, and said dissolution agent is selected from the group consisting of hydrochloric, a mixture of hydrochloric and hydrofluoric acids, fluoroboric acid, nitric acid, phosphoric acid, maleic acid, citric acid, acetic acid, and formic acid, wherein said gelling agent is present in sufficient quantity to gel in the presence of an activating amount of said co-surfactant as said acid spends and multivalent cations ions are generated in situ or are deliberately added. 6. The fluid system of Claim 5 wherein R1 is a hydrocarbon chain of about 15 to about 25 carbon atoms. 7. The fluid system of Claim 6 wherein R1 is further comprised either of an amide group or a carbonyl group, located on between carbon 3 and carbon 10 numbered from the carbon atom bound to X. 8. The fluid system of Claim 7 wherein R1 is wherein m is between about 12 and about 25, preferably between about 15 and about 20, and wherein n is between 2 and 10, preferably between 2 and 8. 9. The fluid system of Claims 5-8 wherein X is comprised of a carboxylate group at its terminus. 10. The fluid system of Claim 9 wherein X is further comprised of a N or P atom within four atoms from said carboxylate group. 11. The fluid system of Claim 10 wherein X is wherein p is between 1 and 5. 12. The fluid system of any one of Claims 5-11 wherein said co-surfactant is wherein x is between about 7 and about 15.