Conserving fresh wash water usage in desalting crude oil

Patent metadata

Field	Value
Publication number	US-10703989-B2
Application number	US-201715719884-A
Country	US
Kind code	B2
Filing date	Sep 29, 2017
Priority date	Sep 29, 2017
Publication date	Jul 7, 2020
Grant date	Jul 7, 2020

Abstract

Methods for conserving the use of fresh wash water in crude oil desalting are described. A crude oil stream including salt mixes with a wash water stream to form an emulsion. The emulsion flows to a desalter, and the wash water coalesces to reform the wash water stream and to transfer at least a portion of the salt from the crude oil stream to the wash water stream. The crude oil stream with reduced salt content separates from the wash water stream. The effluent, which includes the wash water stream, flows from the desalter to a processing unit. The effluent is processed to reduce a concentration of salt in the effluent to be substantially equal to or less than a concentration of salt in the wash water stream. At least a portion of the processed effluent mixes with the crude oil stream before the emulsion flows to the desalter.

First claim

What is claimed is:

1. A method comprising:
mixing a crude oil stream comprising salt with a wash water stream to form an emulsion of wash water in crude oil;
flowing the emulsion to a desalter;
in the desalter:
coalescing the wash water to reform the wash water stream and to transfer at least a portion of the salt from the crude oil stream to the wash water stream, and
separating the crude oil stream with reduced salt content from the wash water stream to which at least the portion of the salt is transferred;

flowing an effluent comprising the wash water stream, to which at least the portion of the salt is transferred, from the desalter to a processing unit;
in the processing unit, processing the effluent to reduce a concentration of salt in the effluent to be substantially less than a concentration of salt in the wash water stream; and
mixing at least a portion of the processed effluent with the crude oil stream before flowing the emulsion to the desalter.

2. The method of claim 1 , wherein mixing the crude oil stream with the wash water stream comprises:
flowing the crude oil stream in a crude oil flowline to the desalter; and
flowing the wash water stream in a wash water flowline to the crude oil flowline before the desalter.

3. The method of claim 2 , wherein mixing at least the portion of the processed effluent with the crude oil stream comprises flowing an effluent stream from the processing unit to the crude oil flowline before the desalter.

4. The method of claim 2 , wherein mixing at least the portion of the processed effluent with the crude oil stream comprises flowing an effluent stream from the processing unit to the wash water flowline before mixing the crude oil stream with the wash water stream.

5. The method of claim 2 , wherein the effluent comprises crude oil, and processing the effluent comprises:
deoiling the effluent to remove at least a portion of the crude oil from the effluent; and
desalinating the effluent to reduce the concentration of salt in the effluent.

6. The method of claim 5 , wherein desalinating the effluent to reduce the concentration of salt in the effluent comprises performing reverse osmosis or an evaporation and condensation process on the effluent.

7. The method of claim 6 , wherein the reverse osmosis is performed at a temperature of up to substantially 60° C.

8. The method of claim 5 , wherein deoiling the effluent to remove at least the portion of the crude oil from the effluent comprises:
flowing the effluent to a gravity separator, a cyclone separator, an induced gas floatation tank, an ultrafiltration unit, or a combination thereof;
separating at least the portion of the crude oil in the effluent from a remainder of the effluent; and
mixing the separated portion of the crude oil with the crude oil stream before flowing the emulsion to the desalter.

9. The method of claim 8 , wherein the effluent comprises dissolved acid gas, and deoiling the effluent comprises stripping the effluent to remove at least a portion of the dissolved acid gas.

10. The method of claim 8 , wherein the effluent comprises dissolved organics, and deoiling the effluent comprises adsorbing at least a portion of the dissolved organics from the effluent on a macro-porous resin.

11. The method of claim 10 , wherein at least the portion of the dissolved organics are adsorbed on the macro-porous resin at a temperature of substantially 60° C.

12. A method comprising:
flowing a mixture of a crude oil stream comprising salt and a wash water stream to a desalter;
in the desalter:
reducing a quantity of salt in the crude oil stream,
increasing a quantity of salt in the wash water stream, and
separating the crude oil stream with reduced salt content from the wash water stream with increased salt content;

flowing an effluent comprising the wash water stream with increased salt content to a processing unit;
in the processing unit:
deoiling the effluent to remove at least a portion of crude oil from the effluent, and
after the deoiling, desalinating the effluent to reduce a quantity of salt in the effluent, such that a concentration of salt in the effluent is substantially less than a concentration of salt in the wash water stream; and

mixing at least a portion of the processed effluent from the processing unit with the crude oil stream before flowing the mixture of the crude oil stream and the wash water stream to the desalter.

13. The method of claim 12 , further comprising mixing the crude oil stream with the wash water stream before flowing the mixture of the crude oil stream and the wash water stream to the desalter.

14. The method of claim 13 , wherein mixing the crude oil stream with the wash water stream comprises:
flowing the crude oil stream in a crude oil flowline to the desalter; and
flowing the wash water stream in a wash water flowline to the crude oil flowline before the desalter.

15. The method of claim 14 , wherein mixing at least the portion of the processed effluent from the processing unit with the crude oil stream comprises flowing an effluent stream from the processing unit to the wash water flowline before mixing the crude oil stream with the wash water stream.

16. The method of claim 14 , wherein mixing at least the portion of the processed effluent from the processing unit with the crude oil stream comprises flowing an effluent stream from the processing unit to the crude oil flowline before the desalter.

17. The method of claim 14 , wherein the effluent comprises crude oil, suspended solids, hydrogen sulfide, and dissolved organics, and deoiling the effluent comprises:
ultrafiltering, separation, induced gas floatation, or a combination thereof to remove at least a portion of the crude oil and at least a portion of the suspended solids from the effluent;
stripping the effluent to remove at least a portion of the dissolved hydrogen sulfide from the effluent; and
adsorbing at least a portion of the dissolved organics from the effluent on a macro-porous resin.

18. The method of claim 17 , further comprising mixing the removed portion of the crude oil from the effluent with the crude oil stream before mixing the crude oil stream with the wash water stream.

19. The method of claim 14 , wherein desalinating the effluent comprises performing reverse osmosis or an evaporation and condensation process on the effluent.

20. The method of claim 19 , wherein the reverse osmosis is performed at a temperature of substantially 60° C.

Assignees

• Saudi Arabian Oil Co

Inventors

• Koleshwar Vilas S
• Albluwi Saif F

Classifications

• B01D17/06

  Separation of liquids from each other by electricity · CPC title

• C10G33/00

  Dewatering or demulsification of hydrocarbon oils (by distillation C10G7/04) · CPC title

• C10G2300/203

  Naphthenic acids, TAN · CPC title

• C10G31/11

  by dialysis · CPC title

• B01D17/047

  with separation aids · CPC title