Aqueous retarded acid solution and methods for use thereof

A method, comprising:

• combining an amount of water and an acid retarding agent (RA) present at a concentration that inhibits activity of acid through a mechanism other than dilution, wherein the acid retarding agent comprises at least one salt compound, wherein at least a portion of the RA is present in solid form;
• dissolving an amount of the acid in the combined amount of water and acid retarding agent to form a non-emulsified composition, wherein the amount of acid comprises up to about 36% by weight of total weight of the composition;
• and
• using a high pressure pump to inject the non-emulsified composition into a wellbore penetrating a subterranean formation having a fracture initiation pressure;
• wherein the acid retarding agent has an estimated retardation factor of at least about 5 at a temperature of 70° F.

A method, comprising:

• combining an amount of water and an acid retarding agent (RA) present at a concentration that inhibits activity of acid through a mechanism other than dilution, wherein the acid retarding agent comprises at least one salt compound and urea, and wherein at least a portion of the RA is present in solid form;
• dissolving an amount of the acid in the combined amount of water and acid retarding agent to form a non-emulsified composition, wherein the acid is present at a concentration between about 37% and 45.7% by weight of the composition;
• and
• injecting the composition into a wellbore penetrating a subterranean formation.