Abstract Water-insoluble polyoxyalkylene graft copolymers are effective anti-foam agents for reducing foaming in crude oil/gas separators The copolymers are of formula: wherein R is an ethylene, propylene or butene group or a mixture thereof; R' is a hydrocarbyl group containing 1 to 8 carbon atoms; R" is a hydroxyl group, an alkoxy group or an alkyl group containing 1 to 8 carbon atoms; (a) is a number in the range 100 to 250; (b) is a number in the range 1 to 6; (c) is a number in the range 1 to 10: and (d) is a number in the range 10 to 100. They are particularly useful in breaking microgas dispersions and foams resulting from crude oils with a high gas to oil ratio.
A method for separating crude oil containing associated gas into liquid oil and free gas in the presence of an anti-foam agent characterised by the fact that the anti-foam agent is a water-insoluble polysiloxane polyoxyalkylene graft copolymer wherein R is an ethylene, propylene or butene group or a mixture thereof; R' is a hydrocarbyl group containing 1 to 8 carbon atoms; R" is a hydroxyl group, an alkoxy group or an alkyl group containing 1 to 8 carbon atoms; (a) is a number in the range 100 to 250; (b) is a number in the range 1 to 6; (c) is a number in the range 1 to 10; and (d) is a number in the range 10 to 100.
Claim 2
Independent Claim
120 words
A method for separating crude oil containing associated gas into liquid oil and free gas in the presence of an anti-foam agent characterised by the fact that the anti-foam agent is a water-insoluble polysiloxane polyoxyalkylene graft copolymer wherein R is an ethylene, propylene or butene group or a mixture thereof; R' is a hydrocarbyl group containing 1 to 8 carbon atoms; R" is a hydroxyl group, an alkoxy group or an alkyl group containing 1 to 8 carbon atoms; (a) is a number in the range 100 to 250; (b) is a number in the range 1 to 6; (c) is a number in the range 1 to 10; and (d) is a number in the range 10 to 100.
Claim 3
Dependent Claim
20 words
A method according to claim 1 wherein the ratio of (a) to (d) is in the range 2:1 to 15:1.
Claim 4
Independent Claim
15 words
A method according to either of the preceding claims wherein R is an ethylene group.
Claim 5
Independent Claim
15 words
A method according to any of the preceding claims wherein R' is a methyl group.
Claim 6
Independent Claim
15 words
A method accordir.g to any of the preceding claims wherein R" is a hydroxyl group.
Claim 7
Dependent Claim
22 words
A method according to claim 5 wherein the ratio of silicon atoms to hydroxyl groups is in the range 2:1 to 16:1.
Claim 8
Independent Claim
23 words
A method according to any of the preceding claims wherein the siloxane content of the copolymer is in the range 30-70% by weight.
Claim 9
Independent Claim
27 words
A method according to any of the preceding claims wherein the copolymer is present in amount 0.1 to 20 ppm expressed on the basis of active ingredient.
Claim 10
Dependent Claim
18 words
A degassed crude oil containing a polysiloxane polyoxyalkylene graft copolymer as defined in any of the preceding claims.
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