Method to produce a scale inhibitor

1. 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 C 1 -C 6 -alkyl, and

(II) from 1 to 95% by weight structural units of formula (II)

wherein

R4 is hydrogen or C 1 -C 6 -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.

2. The method of claim 1 wherein a viscosity of the viscosified treatment fluid after breaking in measure (iii) is less than 5 mPas.

3. The method of claim 1 , wherein the water soluble synthetic polymer material is selected from the group consisting of polymers containing:

(I) 10 to 90% by weight of structural units of formula I, and

(II) 1 to 80% by weight of structural units of formula II,

referred to a total mass of the polymer, with the proviso that the percentage of the structural units of formulae (I) to (II) refer to a total mass of the copolymer and a percentage of the structural units of formulae (I) to (II)-amounts to 100%.

4. The method of claim 1 , wherein a quantity of the synthetic polymer ranges from 0.01 to 10% by weight, referred to a total mass of aqueous polymer solution.

5. The method of claim 1 , wherein the breaker compound is selected from the group of inorganic peroxides, persulfates, percarbonates, and perborates.

6. The method of claim 1 , wherein a quantity of the breaker compound ranges from 0.001 to 5% by weight, referred to a total mass of aqueous polymer solution.

7. The method of claim 1 , wherein the viscosified treatment fluid containing at least a synthetic water soluble gelling agent contains multivalent metal ion.

8. The method of claim 1 , wherein the viscosified treatment fluid is injected as hydraulic fracturing fluid.