Abstract: A method of acidizing a formation penetrated by a wellbore that includes the steps of injecting into the wellbore at a pressure below formation fracturing pressure a treatment fluid that includes a gelling fluid including a gelling agent and a hydrophobically-modified associative polymer, and an aqueous acid; and allowing the treatment fluid to acidize the formation.

Abstract: Methods of acidizing a subterranean formation penetrated by a wellbore that include the steps of (a) injecting into the wellbore at a pressure below subterranean formation fracturing pressure a treatment fluid having a first viscosity and including an aqueous acid and a gelling agent of Formula II: wherein R1 is (CxHy), wherein x ranges from 17 to 21 and y=2x+1 or 2x?1; R5 is hydrogen or —CH3; R6 is —CH2—CH2—CH2—; and R2, R3, and R4 are each —CH3; (b) forming at least one void in the subterranean formation with the treatment fluid; and (c) allowing the treatment fluid to attain a second viscosity that is greater than the first viscosity.