METHOD

1 . A method for increasing the retention of a scale inhibitor within a hydrocarbon producing system, said method comprising the steps of:

(i) pre-flushing said system with a liquid;

(ii) treating said system with a scale inhibitor; and

(iii) over-flushing said system with a composition comprising an ionic polymer and a liquid carrier, wherein the concentration of said ionic polymer in said composition is 5 to 50% wt.

2 . A method as claimed in claim 1 , wherein said pre-flushing and/or said treating step further comprises contacting said system with an ionic polymer.

3 . A method as claimed in claim 1 or 2 , wherein said pre-flushing step comprises contacting system with an ionic polymer.

4 . A method as claimed in any one of claims 1 to 3 , wherein said treating step further comprises treating said system with an ionic polymer.

5 . A method as claimed in any one of claims 1 to 4 , wherein said method comprises the steps of:

(i) pre-flushing said system with a liquid;

(iia) treating said system with an ionic polymer;

(iib) treating said system with a scale inhibitor; and

(iii) over-flushing said system with a composition comprising an ionic polymer and a liquid carrier.

6 . A method as claimed in any one of claims 1 to 4 , wherein said method comprises the steps of:

(i) pre-flushing said system with a liquid;

(ii) treating said system simultaneously with an ionic polymer and a scale inhibitor; and

(iii) over-flushing said system with a composition comprising an ionic polymer and a liquid carrier.

7 . A method as claimed in any preceding claim, wherein said over-flushing step further comprises over-flushing said system with an aqueous fluid.

8 . A method as claimed in any preceding claim, wherein said over-flushing step comprises:

(iiia) over-flushing said system with a composition comprising an ionic polymer and a liquid carrier; and

(iiib) over-flushing said system with an aqueous fluid.

9 . A method as claimed in any preceding claim, wherein said over-flushing step is the final step prior to a shut in period.

10 . A method as claimed in any preceding claim, further comprising the step of shutting in said system.

11 . A method as claimed in any preceding claim, wherein said ionic polymer present in said over-flush is a polyquaternary amine or a polyaminoacid.

12 . A method as claimed in claim 11 , wherein said ionic polymer present in said over-flush is a polyquaternary amine.

13 . A method as claimed in claim 12 , wherein the polyquaternary amine present in said over-flush is formed from monomers of formula (I):

wherein

each of R 1 , R 2 and R 3 is independently hydrogen or an optionally substituted organic radical having from 1 to 20 carbon atoms, preferably 3 to 12 carbon atoms, e.g. 3 to 6 carbon atoms;

R 4 is independently an optionally substituted organic radical having from 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, e.g. 1 to 6 carbon atoms; and

X is a counterion which may optionally be covalently bonded to R 1 , R 2 or R 3 .

14 . A method as claimed in claim 12 , wherein the polyquaternary amine present in said over-flush is formed from monomers of formula (II):

(wherein

R 5 and R 6 are each independently hydrogen or optionally substituted organic radicals having from 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, e.g. 1 to 6 carbon atoms;

each R is independently selected from hydrogen and organic radicals having from 1 to 20 carbon atoms, e.g. 1 to 6 carbon atoms; and

Z is a counterion which may optionally be covalently bonded to either R 5 or R 6 ).

15 . A method as claimed in claim 14 , wherein said polyquaternary amine is formed from diallyl dimethyl ammonium chloride.

16 . A method as claimed in claim 11 , wherein the ionic polymer present in said over-flush is a polyaminoacid, e.g. polyaspartate.

17 . A method as claimed in any preceding claim, wherein said scale inhibitor comprises at least one anionic group, e.g. a carboxylate group or a phosphonate group.

18 . A method as claimed in any preceding claim, wherein said scale inhibitor is a phosphonate, phosphate ester or is a polymer comprising phosphonate or phosphonate ester groups.

19 . A method as claimed in any preceding claim, wherein said scale inhibitor is polymeric.

20 . A method as claimed in any one of claims 2 to 19 , wherein the ionic polymer present in said treatment is a polyquaternary amine, preferably formed from monomers of formula (II):

(wherein

R 5 and R 6 are each independently hydrogen or optionally substituted organic radicals having from 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, e.g. 1 to 6 carbon atoms;

each R is independently selected from hydrogen and organic radicals having from 1 to 20 carbon atoms, e.g. 1 to 6 carbon atoms; and

Z is a counterion which may optionally be covalently bonded to either R 5 or R 6 ).

21 . A method of producing hydrocarbon from a hydrocarbon producing system comprising:

(a) treating said system with a method as defined in any one of claims 1 to 20 ; and

(b) placing said system back on production.

22 . An over-flush composition comprising (e.g. consisting essentially of) a carrier liquid and an ionic polymer (e.g. a polyquaternary amine) as defined in any one of claims 1 and 11 - 16 , wherein the concentration of said ionic polymer in said composition is 5 to 50% wt.