Branched viscoelastic surfactant for high-temperature acidizing

Abstract

A treatment fluid for use in a subterranean formation penetrated by the wellbore of a well includes: (i) water; (ii) a strong acid; and (iii) a branched viscoelastic surfactant having a hydrophobic portion with a total of 16 to 20 carbons; wherein the pH of the treatment fluid is less than 0.5; and wherein the viscosity of the treatment fluid is less than 5 cP at 40 sec-1. A method of treating a zone of a subterranean formation penetrated by a wellbore includes the steps of forming the treatment; (B) introducing the treatment fluid through the wellbore into the zone; and (C) allowing time for the strong acid in the treatment fluid to spend in the formation. Such a treatment fluid shows good rheological properties at temperatures above 93° C. (200° F.).

What is claimed is: 
     
         1 . A treatment fluid for use in a subterranean formation penetrated by the wellbore of a well, the treatment fluid comprising:
 (i) water;   (ii) a strong acid; and   (iii) a branched viscoelastic surfactant having at least one hydrocarbon branch of 16 to 20 carbons;   wherein the treatment fluid has an initial pH of less than 0.5; and   wherein the treatment fluid has a viscosity of less than 5 cP at 40 sec −1  at the initial pH.   
     
     
         2 . The treatment fluid according to  claim 1 , wherein the strong acid comprises hydrochloric acid. 
     
     
         3 . The treatment fluid according to  claim 1 , wherein the treatment fluid does not include hydrogen fluoride. 
     
     
         4 . The treatment fluid according to  claim 1 , wherein the branched viscoelastic surfactant comprises a viscoelastic surfactant having a nitrogen atom with short chain alkyl groups. 
     
     
         5 . The treatment fluid according to  claim 1 , wherein the branched viscoelastic surfactant comprises a quaternary of a branched fatty acid substituted amidoamine. 
     
     
         6 . The treatment fluid according to  claim 5 , wherein the branched viscoelastic surfactant comprises N-Ethyl-N,N-Dimethyl-[(3-Oxoisooctadecyl)Amino]-1-Propanaminium Ethyl Sulfate. 
     
     
         7 . The treatment fluid according to  claim 1 , wherein the treatment fluid additionally comprises: a corrosion inhibitor. 
     
     
         8 . The treatment fluid according to  claim 7 , wherein the corrosion inhibitor is selected from the group consisting of: an aldehyde, quaternary quinolinium, and any combination thereof. 
     
     
         9 . The treatment fluid according to  claim 7 , wherein the treatment fluid additionally comprises: a corrosion inhibitor intensifier. 
     
     
         10 . The treatment fluid according to  claim 9 , wherein the corrosion inhibitor intensifier comprises formic acid.