Well treatment comprising a polymer formed from a diallyl ammonium salt and a scale inhibitor

1. A method for increasing the retention of a scale inhibitor within a hydrocarbon producing system, said method comprising contacting said system with a polymer formed from a diallyl ammonium salt and with said scale inhibitor, wherein said polymer formed from a diallyl ammonium salt has a molecular weight of greater than 50,000.

2. A method as claimed in claim 1 , wherein said scale inhibitor is polymeric.

3. A method as claimed in claim 2 , wherein said scale inhibitor is formed from monomers of formula (IV):

wherein

R 3 is —CO 2 Z, —SO 3 Z, —PO 3 Z 2 or an alkyl or aryl group substituted with at least one —CO 2 Z, —SO 3 Z or —PO 3 Z 2 group in which Z is a hydrogen atom or a univalent metal atom;

R 4 , R 5 and R 6 are each independently hydrogen, an optionally substituted alkyl or aryl group having from 1 to 6 carbon atoms or a group R 3 as hereinbefore defined.

4. A method as claimed in claim 1 , wherein said method comprises squeeze treating said system by introducing said polymer formed from a diallyl ammonium salt and said scale inhibitor into said system and shutting them in a well for at least 1 hour prior to putting the well back into production.

5. A method as claimed in claim 1 , wherein said polymer is formed from monomers of formula (I):

wherein

R 1 and R 2 are each independently hydrogen or substituted organic radicals having from 1 to 20 carbon atoms,

each R is independently selected from hydrogen and organic radicals having from 1 to 20 carbon atoms; and

X is a counterion which may optionally be covalently bonded to either R 1 or R 2 .

6. A method as claimed in claim 1 , wherein said polymer is a homopolymer formed from diallyl dimethyl ammonium chloride.

7. A method as claimed in claim 1 , wherein said scale inhibitor comprises at least one anionic group.

8. A method as claimed in claim 1 , wherein said polymer is applied as a dispersion or solution in a liquid carrier.

9. A method as claimed in claim 1 , wherein said scale inhibitor is applied as a dispersion or solution in a liquid carrier.

10. A method as claimed in claim 1 , wherein said polymer and said scale inhibitor form a solid within the hydrocarbon producing system.

11. A method as claimed in claim 1 , wherein said polymer is applied as a solution having a pH of 1 to 6.

12. A method as claimed in claim 1 , wherein said scale inhibitor is applied as a solution having a pH of 1 to 3.

13. A method as claimed in claim 1 , wherein said polymer formed from a diallyl ammonium salt has a molecular weight of between 55,000 to 2,000,000.

14. A method as claimed in claim 1 , wherein said scale inhibitor comprises at least one carboxylate group.

15. A hydrocarbon well treatment composition comprising:

a carrier liquid;

a homopolymer formed from a diallyl ammonium salt having a molecular weight of greater than 50,000, wherein the concentration of said homopolymer is 1 to 10 wt%; and

a scale inhibitor.

16. A composition as claimed in claim 15 , wherein said polymer formed from a diallyl ammonium salt has a molecular weight of between 55,000 to 2,000,000.

17. A kit for increasing the retention of a scale inhibitor within a hydrocarbon producing system, said kit comprising:

a polymer formed from diallyl ammonium salt having a molecular weight of greater than 50,000; and

separately from the polymer a scale inhibitor.

18. A kit as claimed in claim 17 , wherein said polymer formed from a diallyl ammonium salt has a molecular weight of between 55,000 to 2,000,000.