Method

Abstract

The invention provides a method for increasing the retention of a scale inhibitor within a hydrocarbon producing system, including 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.

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.