Patent ID: 8895481
Filing Date: 2014-11-25
Classification: C09K,C23F

Abstract:
1. A method of treating a wellbore, the method comprising introducing an acid treatment fluid through the wellbore, the treatment fluid comprising from 0.5 to 5.5% by weight of a zwitterionic viscoelastic surfactant, an acid in an amount more than 15% by weight to provide the treatment fluid with an initial pH of ≦0 and a rheology enhancer selected from at least one of a polyvinyl ester, a polyvinyl acetate, a polyacrylate and a sulfonate-containing polymer, and combinations thereof, the zwitterionic viscoelastic surfactant comprises a surfactant or mixture of surfactants having the formula: wherein R is an alkyl group that contains from about 17 to about 23 carbon atoms which may be branched or straight chained and which may be saturated or unsaturated: a, b, a′, and b′ are each from 0 to 10 and m and m′ are each from 0 to 13, a and b are each 1 or 2 if m is not 0 and (a+b) is from 2 to 10 if m is 0: a′ and b′ are each 1 or 2 when m′ is not 0 and (a′+b′) is from 1 to 5 if m′ is 0; (m+m′) is from 0 to 14; and CH