US Patent 9255468 Chelating agent-based self-diverting acidizing fluids and methods relating thereto

Complexing-acidizing treatment fluids can be used in various subterranean treatment operations. Some methods include: providing or preparing a complexing-acidizing treatment fluid having an acid concentration of about 0.6 Molar, the complexing-acidizing treatment fluid including: an aminopolycarboxylic acid chelating agent, an aqueous base fluid, and an acid, placing the complexing-acidizing treatment fluid in a subterranean formation matrix penetrated by a well bore; allowing the acid to generate metal cations by dissolution of the subterranean formation matrix; reacting the aminopolycarboxylic acid chelating agent with the metal cations so as to form at least a plurality of aggregate blocking agents; and allowing the aggregate blocking agents to divert the complexing-acidizing treatment fluid to a main channel in the subterranean formation matrix that is distinct from a wormhole in the subterranean formation matrix.