Produced water treatment and solids precipitation from thermal treatment blowdown

Patent metadata

Field	Value
Publication number	US-10132145-B2
Application number	US-201314428213-A
Country	US
Kind code	B2
Filing date	Aug 22, 2013
Priority date	Sep 13, 2012
Publication date	Nov 20, 2018
Grant date	Nov 20, 2018

Abstract

Produced water, for example from a steam assisted gravity drainage (SAGD) or cyclic steam stimulation (CSS) heavy oil recovery operation, is treated to recover water that is re-used to create steam. The produced water is treated in one or more thermal treatment devices such as an evaporator and a crystallizer. The thermal treatment produces a slurry comprising dispersed or dissolved salts and organic compounds. A water-miscible solvent for one or more of the organic compounds, for example methanol, is added to the slurry. The solids precipitate and are separated from the slurry. The solvent may be recovered for re-use in treating more slurry.

First claim

The invention claimed is:

1. A process for extracting oil comprising the steps of:
a) producing steam;
b) injecting the steam into a formation comprising oil;
c) withdrawing a mixture of water and oil from the formation;
d) separating produced water from the mixture of water and oil;
e) treating the produced water to produce a distillate and a concentrate, the concentrate containing one or more salts and one or more organic compounds;
f) using the distillate to produce additional steam for injection into the formation;
g) mixing a solvent of the one or more organic compounds with the concentrate;
h) after step g), separating precipitated solids comprising the one or more salts from the mixture; and
i) recovering the solvent from the mixture with the concentrate and mixing recovered solvent with additional concentrate from step e).

2. The process of claim 1 wherein the oil is heavy oil or bitumen.

3. The process of claim 1 , wherein steps a), b), and c) are part of a steam assisted gravity drainage (SAGD) or cyclic steam stimulation (CSS) operation.

4. The process of claim 1 wherein step e) comprises treating the produced water with an evaporator to produce an evaporator blowdown and treating the evaporator blowdown in a crystallizer to produce the concentrate.

5. The process of claim 1 wherein the solvent comprises methanol.

6. The process of claim 1 wherein the precipitated solids comprise silica.

7. The process of claim 1 comprising a step of removing the concentrate from the process after the steps of recovering solvent and separating precipitated solids.

8. The process of claim 1 comprising treating the one or more organic compounds in the concentrate and returning treated concentrate to the process at or upstream of step e).

9. A method for treating a mixture of water, one or more salts in solution and one or more organic compounds, the method comprising the steps of:
a) removing water from the mixture to produce a concentrate, wherein the concentrate contains one or more of the organic compounds and one or more of the salts at a super-saturated concentration;
b) mixing the concentrate with a solvent of the one or more organic compounds;
c) removing solids comprising precipitates of the one or more salts previously at super-saturated concentrations from the concentrate; and
d) recovering at least some of the solvent from the mixture of concentrate and solvent.

10. The method of claim 9 further comprising a step of mixing recovered solvent with additional concentrate from step a).

11. The method of claim 9 wherein the water comprises produced water.

12. The method of claim 11 wherein the produced water is extracted from a heavy oil containing formation after injecting steam into the formation.

13. The method of claim 9 wherein the concentrate comprises blowdown from one or more thermal treatment devices.

14. The method of claim 13 wherein the thermal treatment devices comprise an evaporator and a crystallizer.

15. The method of claim 9 further comprising a step of treating at least some of the concentrate after step c) to oxidize or remove the one or more organic compounds and returning the treated concentrate to step a).

16. The method of claim 9 wherein the concentrate at step a) is an aqueous composition comprising at least 40 wt % of total dissolved solids (TS).

17. The method of claim 9 wherein the mass of the solvent is at least equal to the mass of the concentrate.

18. The method of claim 9 wherein the solvent is selected from the group consisting of a) methanol and b) ethanol.

19. The method of claim 9 wherein the mixture resulting from step b) has a temperature of 40 degrees C. or more, wherein the temperature of the mixture is below the boiling point of the solvent.

20. The method of claim 9 wherein the solids further comprise the one or more organic compounds.

21. An apparatus for treating produced water comprising:
a) one or more thermal treatment devices configured to treat the produced water and produce a blowdown stream;
b) a solvent mixing vessel, the solvent mixing vessel in communication with the blowdown stream;
c) a solvent feeding system in communication with the solvent mixing vessel, the solvent feeding system having a solvent for one or more organic compounds;
d) a solid-liquid separation device; and
e) a solvent recovery system downstream of the solvent mixing vessel.

22. The apparatus of claim 21 further wherein the solid-liquid separation device is incorporated with, or downstream of, the solvent mixing vessel.

23. The apparatus of claim 21 wherein the one or more thermal treatment devices comprise two or more thermal treatment devices in series.

24. The apparatus of claim 23 wherein the two or more thermal treatment devices comprise an evaporator and a crystallizer.

25. The apparatus of claim 21 wherein the solvent recovery system comprises a heat exchanger to cool recovered solvent.

26. The apparatus of claim 21 further comprising a treatment system adapted to oxidize or remove organic compounds downstream of the solvent recovery system.

27. A process for treating produced water from heavy oil extraction comprising the steps of:
a) de-oiling the produced water;
b) treating the de-oiled produced water in an evaporator to produce an evaporator blowdown;
c) treating the evaporator blow down in a crystallizer to produce a crystallizer blowdown;
d) adding a solvent selected from the group consisting of methanol and ethanol to the crystallizer blowdown;
e) separating solids from the crystallizer blowdown; and
f) after step d), recovering at least some of the solvent from the crystallizer blowdown.

28. The process of claim 27 further comprising a step of cooling the recovered solvent such that in step d) the recovered solvent cools the crystallizer blowdown to below the boiling point of the solvent.

29. The process of claim 27 wherein step d) comprises producing a mixture of the solvent and crystallizer blowdown having a temperature of 40 degrees C. or more, wherein the temperature of the mixture is below the boiling point of the solvent.

30. The process of claim 27 further comprising a step of treating the crystallizer blowdown to remove or oxidize one or more organic compounds in the slurry and returning treated slurry to, or upstream of, step b).

Assignees

• Bl Technologies Inc

Inventors

• Xia Jiyang
• Peng Wenqing
• Yang Hai
• Liu Chunjie
• Wei Chang
• Cai Wei
• Sun Yiwen

Classifications

• B01D11/0288

  Applications, solvents · CPC title

• B01D2009/0086

  Processes or apparatus therefor · CPC title

• E21B43/40

  Separation associated with re-injection of separated materials {(E21B43/385 takes precedence)} · CPC title

• C02F1/42

  by ion-exchange (ion-exchange in general B01J) · CPC title

• E21B43/2406 Primary

  Steam assisted gravity drainage [SAGD] · CPC title