Method of inhibiting scale in a geological formation

1. A method of inhibiting scale in a geological formation comprising:

(a) depositing an organosilane on a surface of the geological formation;

(b) delivering a nano-material comprising carboxy-functionalised multi-wall carbon nanotubes or fullerene to the surface of the geological formation whereby to cause adherence by a chemical interaction between the nano-material and the organosilane, wherein the nano-material provides one or more adsorption sites for a polycarboxylic acid-based scale inhibitor;

(c) emplacing a quantity of the polycarboxylic acid-based scale inhibitor in the geological formation so that an amount of the polycarboxylic acid-based scale inhibitor is adsorbed by the nano-material; and

(d) inhibiting scale in the geological formation by sustained release of the amount of the polycarboxylic acid-based scale inhibitor from the nano-material into the geological formation.

2. The method as claimed in claim 1 , wherein the nano-material comprises carbon nanotubes having a linear dimension in the range from 0.5 nm to 2000 nm.

3. The method as claimed in claim 1 , wherein the nano-material comprises carbon nanotubes including one or more defects.

4. The method as claimed in claim 1 , wherein the organosilane chemically bonds to the geological formation when it is deposited on the surface of the geological formation.

5. The method as claimed in claim 1 , wherein the organosilane is a binder.

6. The method as claimed in claim 1 , wherein the organosilane has an amino group.

7. The method as claimed in claim 1 , wherein the chemical interaction between the nano-material and the organosilane is a chemical bond.

8. The method as claimed in claim 7 , wherein the chemical bond between the nano-material and the organosilane includes an amide bond.

9. The method as claimed in claim 1 , wherein the polycarboxylic acid-based scale inhibitor is polyphosphinocarboxylic acid or diethylenetriamine-penta-methylene phosphonic acid.

10. The method as claimed in claim 1 , wherein step (c) comprises the sub-steps:

(c)(i) pumping the quantity of the polycarboxylic acid-based scale inhibitor into the geological formation via a well;

(c)(ii) shutting in the well until the amount of the scale inhibitor is adsorbed by the nano-material; and

(c)(iii) re-opening the well.

11. The method as claimed in claim 1 , further comprising:

(e) emplacing a further quantity of the polycarboxylic acid-based scale inhibitor in the geological formation so that a further amount of the polycarboxylic acid-based scale inhibitor is adsorbed by the nano-material.

12. The method as claimed in claim 11 , further comprising:

(f) inhibiting scale in the geological formation by sustained release of the further amount of the polycarboxylic acid-based scale inhibitor from the nano-material into the geological formation.

13. A kit of parts for performing the method as claimed in claim 1 , the kit of parts comprising:

an organosilane;

a nano-material comprising carboxy-functionalised multi-wall carbon nanotubes or fullerene capable of adhering to the organosilane by a chemical interaction between the nano-material and the organosilane wherein the nano-material provides one or more adsorption sites; and

a polycarboxylic acid-based scale inhibitor capable of adsorbing to the adsorption sites on the nano-material.

14. A kit of parts as claimed in claim 13 , wherein the nano-material is carbon nanotubes.

15. The method as claimed in claim 1 , wherein the carbon nanotubes comprise nano-particles which have a linear dimension in the range from 0.5 nm to 2000 nm.

16. The method as claimed in claim 15 , wherein the nano-particles include one or more defects.

17. A method of inhibiting scale in a geological formation as claimed in claim 1 , wherein the nano-material is carbon nanotubes.