Water treatment method for heavy oil production using calcium sulfate seed slurry evaporation

• US 20050279500A1
• Filed: 06/08/2005
• Published: 12/22/2005
• Est. Priority Date: 05/07/1999
• Status: Active Grant

• Current Assignee: GE Ionics Incorporated (Veolia Environnement SA)
• Original Assignee: GE Ionics Incorporated (Veolia Environnement SA)
• Inventors: Heins, William F.
• Granted Patent: US 7,438,129 B2
• Time in Patent Office: Days
• US Class Current: 166/266
• CPC Class Codes: C02F 1/02 by heating methods of steam generation F22B; preheating boiler feed-water or accumulating preheated boiler feed-water F22D
• CPC Class Codes: C02F 1/04 by distillation or evaporation
• CPC Class Codes: C02F 1/041 by means of vapour compression
• CPC Class Codes: C02F 1/048 Purification of waste water by evaporation
• CPC Class Codes: C02F 1/08 Thin film evaporation
• CPC Class Codes: C02F 1/40 Devices for separating or removing fatty or oily substances or similar floating material cleaning or keeping clear the surface of open water from oil or like materials E02B15/04; devices in sewers for separating liquid or solid substances from sewage E03F5/14, e.g. for use in drains leading to the sewer E03F5/16
• CPC Class Codes: C02F 1/42 by ion-exchange ion-exchange in general B01J
• CPC Class Codes: C02F 1/46 by electrochemical methods
• CPC Class Codes: C02F 1/469 by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
• CPC Class Codes: C02F 1/56 Macromolecular compounds
• CPC Class Codes: C02F 1/66 by neutralisation; pH adjustment for degassing C02F1/20; using ion-exchange C02F1/42; for flocculation or precipitation of suspended impurities C02F1/52; for removing dissolved compounds C02F1/58
• CPC Class Codes: C02F 2103/023 Water in cooling circuits
• CPC Class Codes: C02F 2103/10 from quarries or from mining activities
• CPC Class Codes: C02F 2103/365 from petrochemical industry (e.g. refineries)
• CPC Class Codes: C02F 9/00 Multistage treatment of water, waste water or sewage
• CPC Class Codes: E21B 43/2406 Steam assisted gravity drainage [SAGD]
• CPC Class Codes: E21B 43/2408 SAGD in combination with other methods
• CPC Class Codes: Y10S 159/901 Promoting circulation
• CPC Class Codes: Y10S 203/17 Saline water conversion

Abstract

A process for treating produced water to generate high pressure steam. Produced water from heavy oil recovery operations is treated by first removing oil and grease. Feedwater is then acidified and steam stripped to remove alkalinity and dissolved non-condensable gases. Pretreated produced water is then fed to an evaporator. Up to 95% or more of the pretreated produced water stream is evaporated to produce (1) a distillate having a trace amount of residual solutes therein, and (2) evaporator blowdown containing substantially all solutes from the produced water feed. The distillate may be directly used, or polished to remove the trace residual solutes before being fed to a steam generator. Steam generation in a packaged boiler, such as a water tube boiler having a steam drum and a mud drum with water cooled combustion chamber walls, produces 100% quality high pressure steam for down-hole use.

Claims

1. A process for producing steam for downhole injection in the recovery of heavy oil, said process comprising:

(a) providing an oil/water mixture gathered from an oil/water collection well;

(b) separating oil from said oil/water mixture to provide an oil product and a produced water product containing oil therein;

(c) de-oiling said oil containing produced water product to at least partially provide an evaporator feedwater stream, said evaporator feedwater stream comprising water, dissolved gases, and dissolved solutes, said dissolved solutes comprising calcium, sulfate, and silica;

(d) providing an evaporator having a plurality of heat transfer elements, a liquid containing sump reservoir, and a recirculating pump to recycle liquid from said sump into a heat transfer relationship with said heat transfer elements;

(e) acidifying said feedwater to convert alkalinity to carbon dioxide, and steam stripping said carbon dioxide and said dissolved gases from said evaporator feedwater stream;

(f) injecting said evaporator feedwater stream into said evaporator and evaporating a portion of said feedwater stream to produce a concentrated brine;

(f) recirculating said concentrated brine in said evaporator, said concentrated brine comprising a slurry comprising water, dissolved solutes, calcium sulfate. and silica crystals;

(g) distributing said concentrated brine on a first surface of at least one of said plurality of heat transfer elements to generate a steam vapor;

(h) slightly compressing said steam vapor to produce a compressed steam vapor;

(i) directing said compressed steam vapor to a second surface of at least one of said plurality of heat transfer elements to condense said compressed steam vapor and to form a distillate

(j) collecting said distillate stream;

(k) discharging at least some of said concentrated brine as an evaporator blowdown stream;

(l) introducing said distillate stream into a steam generator, to produce

(i) high pressure steam,

(ii) a boiler blowdown stream, said boiler blowdown stream comprising water and residual dissolved solids;

(m) injecting said high pressure steam in an injection well to fluidize oil present in a selected geological formation, to produce an oil and water mixture;

(n) gathering said oil/water mixture.

2. The process as set forth in claim 1, wherein said distillate stream comprises residual solutes, further comprising the step of removing residual solutes from said distillate stream to produce a substantially solute free distillate stream.

3. The process as set forth in claim 2, wherein said residual solutes in said distillate comprise non-volatile total organic carbon constituents.

4. The process as set forth in claim 2, wherein said residual solutes in said distillate comprise hardness.

5. The process as set forth in claim 2, further comprising the step of cooling said evaporator distillate prior to removal of said residual solutes.

6. The process as set forth in claim 5, wherein said method further comprises the step of heating said substantially solute free treated boiler feedwater stream before introducing said stream into said boiler.

7. The process as set forth in claim 2, wherein said residual solutes in said distillate are removed via ion exchange treatment.

8. The process as set forth in claim 2, wherein said residual solutes are removed via membrane separation, wherein a solute containing membrane reject stream is produced.

9. The process as set forth in claim 8, wherein said membrane separation method comprises electrodeionization.

10. The process as set forth in claim 1, further comprising the step of removing said residual solutes from said distillate stream in an electrodeionization treatment unit to produce (a) a substantially solute free feedwater and (2) a solute containing reject stream.

11. The process as set forth in claim 10, further comprising, before injecting said evaporator feedwater stream into said evaporator, returning said electrodeionization reject stream to said evaporator feedwater stream for treatment in said evaporator.

12. The process as set forth in claim 8, wherein said membrane separation method comprises reverse osmosis.

13. The process as set forth in claim 1, wherein said process further comprises the step of adding said boiler blowdown stream to said evaporator feedwater.

14. The process as set forth in claim 1, wherein said evaporator further comprises a sump reservoir, and wherein said boiler blowdown is directly injected into said sump reservoir.

15. The process as set forth in claim 1, wherein said boiler blowdown is injected into said recirculating brine at a location upstream of said recirculation pump.

16. The process as set forth in claim 1, wherein said evaporator feedwater further comprises dissolved gases, and wherein said process further comprises heating said evaporator feedwater to remove at least some of said dissolved gases from said evaporator feedwater, prior to injection of said feedwater into said evaporator.

17. The process as set forth in claim 9, wherein said boiler blowdown stream is added to said evaporator feedwater before heating said evaporator feedwater.

18. The process as set forth in claim 1, wherein the pH of the recirculating brine is raised to a pH of at least 7.5 by adding a selected base to said liquid sump reservoir.

19. The process as set forth in claim 18, wherein said evaporator further comprises a feed tank, and wherein the pH of the recirculating brine is raised to a pH of at least 8.5 by adding a selected base to said liquid sump reservoir.

20. The process as set forth in claim 1, wherein the pH of the recirculating brine is raised to a pH of at least 7.5 by injection of a selected base into said recirculating brine.

21. The process as set forth in claim 1, wherein the pH of the recirculating brine is raised to a pH of at least 8.5 by injection of said selected base to said recirculating brine.

22. The process as set forth in claim 21, wherein said selected base is injected into said recirculating liquid prior to said recirculating pump.

23. The process as set forth in claim 18, wherein said selected base comprises sodium hydroxide.

24. The process as set forth in claim 1, wherein said evaporator is a falling-film type evaporator.

25. The process as set forth in claim 1, wherein said evaporator is a forced-circulation type evaporator.

26. The process as set forth in claim 24, wherein said heat transfer elements are tubular elements having an interior surface and an exterior surface.

27. The process as set forth in claim 26, wherein said heat transfer elements are tubular elements having an interior surface and an exterior surface.

28. The process as set forth in claim 27, wherein said evaporator feedwater is concentrated at the interior surface of said tubular heat transfer elements.

29. The process as set forth in claim 24 wherein said evaporator comprises a mechanical vapor recompression evaporator.

30. The process as set forth in claim 25 wherein said evaporator comprises a mechanical vapor recompression evaporator.

31. The process as set forth in claim 1, further comprising the step of treating said evaporator blowdown stream in a crystallizer.

32. The process as set forth in claim 1, further comprising the step of treating said evaporator blowdown stream in a spray dryer.

33. The process as set forth in claim 1, further comprising removing oil from said feedwater stream to a selected oil concentration before injecting said evaporator feedwater stream into said evaporator.

34. The process as set forth in claim 33, wherein the selected concentration of oil in said feedwater stream comprises less than about twenty parts per million.

35. The process as set forth in claim 7, further comprising the step of regenerating said ion exchange resin to generate an ion exchange regenerant stream, and still further comprising returning said ion exchange regenerant stream to said evaporator feedwater prior to injecting said evaporator feedwater into said evaporator.

36. The process as set forth in claim 1, wherein said boiler comprises a packaged boiler.

37. The process as set forth in claim 36, wherein said packaged boiler comprises a water tube boiler.

38. The process as set forth in claim 1, wherein said boiler comprises a once-through steam generator.

39. The process as set forth in claim 38, further comprising, generating steam in said once through steam generator, the step of separating steam and liquid, to produce a steam stream having substantially 100% steam quality.

40. The process as set forth in claim 39, wherein said 100% steam quality stream is injected in said injection wells.

41. The process as set forth in claim 39, wherein said step of separating said steam and said liquid comprised producing a liquid stream containing dissolved solutes, and wherein said liquid stream is flashed at least once to produce a still further concentrated residual liquid containing dissolved solutes.

42. The process as set forth in claim 41, further comprising the step of adding said residual liquid stream containing dissolved solutes to said evaporator feedwater stream.

43. A process for treatment of a produced water stream resulting from the production of oil from heavy oil reserves, said produced water stream comprising dissolved solutes including calcium, sulfate, silica, alkalinity, and non-condensable gases, and wherein said treatment comprises:

(a) acidification of said produced water stream, to remove alkalinity by conversion to free carbon dioxide;

(b) steam stripping said produced water stream to remove said non-condensable gases and said carbon dioxide produced in said alkalinity removal step;

(c) evaporation of said produced water stream to produce a slurry comprising water, dissolved solutes, calcium sulfate, and silica, to generate (i) a distillate stream at about 95% or more by volume of said produced water stream and (ii) a blowdown stream at about 5% or less by volume of said produced water stream;

(d) generating a steam stream at about 100% quality and at about 1000 pounds per square inch pressure or more from said distillate stream, and wherein said steam stream comprises at least about 70% by weight of said distillate stream, and generating a blowdown stream of at least about 30% or less by weight of said distillate stream.

44. The process as set forth in claim 43, wherein said steam stream comprises at least 95% by weight of said distillate stream.

45. The process as set forth in claim 44, wherein said steam stream comprises at least 98% by weight of said distillate stream.

46. The process as set forth in claim 45, where said blowdown stream is added to and mixed with said produced water stream prior to evaporation of said produced water stream.

47. The process as set forth in claim 43, wherein evaporation of said produced water stream is accomplished in a falling film evaporator.

48. The process as set forth in claim 43, wherein the produced water stream treated with acid to lower the pH to convert alkalinity to free carbon dioxide.

49. The process as set forth in claim 43, wherein said evaporate comprises a heat transfer surface, and wherein said slurry of calcium sulfate and silica is maintained at a preselected concentration for preferential precipitation of said calcium, said sulfate, and said silica to said seeds rather than to said heat transfer surfaces of said evaporator.