Using a complex emulsion for treating a subterranean formation, such as to dissolve minerals therein (e.g. carbonates, scales, and/or filter cake) to improve permeability, substantially improves post treatment fluid clean-up for improved hydrocarbon production. The complex emulsion is made by mixing an acid aqueous phase with an oil external microemulsion to give an initial product, where the acid aqueous phase is an external phase and the microemulsion is an internal phase. Then the initial product is mixed with a second oil (e.g. xylene, diesel, toluene, kerosene, other aromatics, refined hydrocarbons and the like) containing an emulsifier to make a complex emulsion.