Abstract: A composition in the form of an emulsion is provided, the composition including: (i) a continuous oil phase; (ii) an internal aqueous acid phase adjacent the continuous oil phase; and (iii) a source of ammonium ion, wherein the ammonium ion has: (a) at least one ammonium ion; (b) an organic group with at least 40 carbon atoms; (c) at least 40 carbon atoms per ammonium ion; (d) a carbon to nitrogen ratio of at least 20 carbon atoms per nitrogen atom; and (e) at least one alkyl branch on the organic group. In addition, a method of acidizing a subterranean formation is provided, the method including the steps of: (A) forming a treatment fluid comprising a composition according to the invention; and (B) introducing the treatment fluid into the well.