Hydroxy polyesters and uses as biodegradable demulsifiers
Hydroxyl polyester compounds or compositions which are useful as oilfield demulsifiers are prepared through esterifying carboxylic compounds and epoxide compounds under controlled molar ratios. The hydroxyl polyesters are useful as biodegradable demulsifiers on oil productions.
1. A process for demulsifing a water-in-oil emulsion, wherein the water-in-oil emulsion is contacted with a biodegradable demulsifier comprising an amphiphilic hydroxyl polyester, wherein the ester bond of the demulsifier is formed by the reaction of one carboxylic compound with at least two carboxylic groups on molecule with at least one epoxide compound with monoepoxide group.
2. The process of claim 1 , wherein the demulsifier comprises a block amphiphilic hydroxyl polyester.
3. The process of claim 1 , wherein the demulsifier comprises a star or branched amphiphilic hydroxyl polyester.
4. The process of claim 1 , wherein the carboxylic acid group of the demulsifier is a molar excess to another reactive organic group.
5. The process of claim 1 , wherein the molar ratio of carboxylic group to epoxide group is from 1.90:1 to 1.01:1.
6. The process of claim 1 , wherein the esterification reactions between epoxide compounds and carboxylic acid compounds are carried out in melt, solution or solution mixtures.
7. The process of claim 1 , wherein the water-in-oil emulsion is a crude oil emulsion.
8. The process of claim 1 , wherein the carboxylic acid group is a molar excess to the reactive monoepoxide group.
9. The process of claim 1 , wherein the reaction is carried out at a temperature from room temperature to 200° C. at ambient pressure with or without addition of catalyst.
10. The process of claim 1 , further comprising a filtration or centrifugation step to remove unreacted compounds or impurities.
11. A composition for demulsifying a water-in-oil emulsion, the composition comprising a biodegradable amphiphilic hydroxyl polyester, wherein the ester bond of the demulsifier is formed by the reaction of one carboxylic compound with at least two carboxylic groups on molecule with at least one epoxide compound with monoepoxide group.