Inorganic deposit inhibitors, in particular in oil wells, particularly in high pressure/high temperature conditions
OwnerChristian Hurtevent, Rosangela Pirriinventors
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Abstract
The invention concerns inorganic deposit inhibitors, in particular in oil wells. Said inhibitors comprise a water soluble copolymer consisting of (in mol % of polymerised monomers): a) 5 to 95% of styrenesulphonic acid or one of its salts; b) 5 to 95% of vinylsulphonic acid or one of its salts; c) 0 to 20% of one or several non-ionizable unsaturated monomers. They are particularly efficient against calcium carbonate and/or barium sulphate deposits. They are capable of being used in accordance with a so-called squeeze process in HP/MT conditions with desorption compatible with the desired treatment duration.
Claims10
1- water soluble copolymer comprising (in mole % of polymerised monomers):
- a) 5 to 95% of styrenesulphonic acid or one of its salts;
- b) 5 to 95% of vinylsulphonic acid or one of its salts;
- c) 0 to 20% of one or several non-ionisable unsaturated monomers, with the exception of monomers of the following formula:
- 1
- wherein R1 and R2 are, independently of each other, a hydrogen, a C1 to C4 alkyl, an ammonium ion or an alkali metal or alkaline earth metal ion.
2- Copolymer according to claim 1, consisting of (in mole % of polymerised monomers):
- a) 10 to 45% of styrenesulphonic acid or one of its salts;
- b) 55 to 90% of vinylsulphonic acid or one of its salts.
3- Copolymer according to claims 1 or 2, wherein all or part of the sulphonic acids are replaced by their alkaline metal salts or their ammonium salts or their quaternised amine salts.
4- Copolymer according to any of claims 1 to 3, wherein the styrenesulphonic acid is 4-styrenesulphonic acid.
5- Copolymer according to any of claims 1 to 4, with a molar mass (by number) between 3 000 and 50 000 and preferably between 5 000 and 30 000.
6- Copolymer according to any of claims 1 to 5, with a dispersity index Mw/Mn less than or equal to 3.
7- Inorganic deposit inhibitor consisting of a copolymer according to any of claims 1 to 6.
8- Process for preparing a copolymer according to any of claims 1 to 6, wherein it comprises polymerising monomers in aqueous, water/alcohol or alcohol solution, in the presence of a free radical initiator and at a temperature of between 40 and 120° C.
9- Use of the inorganic deposit inhibitor according to claim 7 in oil wells.
Use according to claim 9 according to the squeeze process, consisting in injecting sea water into the well, then injecting the fluid containing the inhibitor into the well and injecting once again a flow of sea water.
Dependencies are inferred from the claim text.