Patent ID: 8071511

Claim:
A method for treating a downhole wellbore tubular or subsurface completion equipment, the method comprising the steps of: (A) determining the likelihood of the presence of scale in the downhole wellbore tubular or subsurface completion equipment; (B) forming or providing a treatment fluid comprising: (i) water; (ii) a chelating agent capable of forming a heterocyclic ring that contains a metal ion attached to at least two nonmetal ions; and (iii) a viscosity-increasing agent, wherein the viscosity-increasing agent comprises a polymeric material and wherein the viscosity-increasing agent is at a concentration in the treatment fluid that is at least sufficient to make the viscosity of the treatment fluid greater than 5 cP when measured at 511 reciprocal seconds on a Fann 35A model viscometer with a number 1 spring and bob; (C) introducing the treatment fluid into the downhole wellbore tubular or the subsurface completion equipment; (D) allowing the treatment fluid sufficient time to dissolve scale in the downhole wellbore tubular or the subsurface completion equipment; and (E) flowing back the treatment fluid from the downhole wellbore tubular or the subsurface completion equipment without breaking the viscosity of the fluid.