Method to produce a scale inhibitor

A method for preparation of a scale inhibitor comprising:

• providing a viscosified treatment fluid containing at least water, a water soluble polymeric gelling agent, an oxidizing breaker compound, and no external scale inhibitor agent, wherein the water contains at least 1,000 ppm total dissolved solids (TDS);
• (ii) pumping the viscosified treatment fluid into a formation and
• (iii) allowing the oxidizing breaker compound to degrade the water soluble polymeric gelling agent being a synthetic polymer comprising:
• (I) at least structural units of formula (I)
• wherein
• R1, R2 and R3 independently are hydrogen or C1-C6-alkyl, and
• (II) from 1 to 95% by weight structural units of formula (II)
• wherein
• R4 is hydrogen or C1-C6-alkyl,
• R5 is hydrogen, a cation of an alkaline metal, of an earth alkaline metal, of ammonia and/or of an organic amine,
• A is a covalent C—S bond or a two-valent organic bridging group,
• after the breaker degrading the synthetic polymer into oligomeric or monomeric chain fragments;
• and
• the oligomeric or monomeric chain fragments preventing scale depositing in the formation.