Method of acidizing a subterranean formation with diverting foam or fluid

Abstract From the Canadian patent

A method of acidizing a subterranean formation with a diverting agent composed of a gelled or thickened viscoelastic foam or fluid generated from (i.) an amidoamine oxide gelling agent and (ii.) an acid or foam water and/or brine. The gelled or thickened foam or fluid may be generated in-situ or introduced directly into the formation by mixing of the amidoamine oxide gelling agent and acid or foam water and/or brine. As the acid spends the acidizing fluid thickens. When the acid is further spent the fluid viscosity declines eventually returning to a low viscosity state allowing for easy cleanup. The process allows for selective acidizing of less permeable zones of the formation and more …