초록 ▼

An evaporation based method of treating produced water from heavy oil production. A produced water from heavy oil recovery operations treated by first removing oil and grease to a desired level, preferably to about twenty parts per million, or less. If necessary, the pH is then adjusted, normally do

An evaporation based method of treating produced water from heavy oil production. A produced water from heavy oil recovery operations treated by first removing oil and grease to a desired level, preferably to about twenty parts per million, or less. If necessary, the pH is then adjusted, normally downward and by acid addition, to release at least some carbonate alkalinity as free carbon dioxide. Preferably, all non-hydroxide alkalinity is removed, or substantially so, by introducing the feedwater into a decarbonator. Feedwater is introduced into an evaporator, and the feedwater is evaporated to a selected concentration factor to produce (1) a distillate having a small amount of residual solutes, and (2) evaporator blowdown containing residual solids. Distillate may be directly used for steam generation in a once-through steam generator, or polished by ion exchange or electrodeionization prior to feed to a packaged boiler. In either case, 100% quality steam is produced, directly in indirectly, for downhole use.

대표청구항 ▼

The invention claimed is: 1. A method of producing steam for downhole injection in the recovery of heavy oil, said method comprising: (a) providing an oil/water mixture gathered from an oil/water collection well, (b) substantially separating oil from said oil/water mixture to provide an oil product

The invention claimed is: 1. A method of producing steam for downhole injection in the recovery of heavy oil, said method comprising: (a) providing an oil/water mixture gathered from an oil/water collection well, (b) substantially separating oil from said oil/water mixture to provide an oil product and an oil containing produced water; (c) de-oiling said oil containing produced water to at least partially provide an evaporator feedwater, said evaporator feedwater comprising water, dissolved solutes, and dissolved gases, said dissolved solutes comprising silica (d) heating said evaporator feedwater to remove at least some of said dissolved gases; (e) injecting said evaporator feedwater into an evaporator, and concentrating said evaporator feedwater to produce a concentrated heated brine, said evaporator having a plurality of heat transfer surfaces; (f) maintaining the pH of said concentrated heated brine as necessary to maintain solubility of silica therein at a selected concentration factor; (g) distributing said brine on a first surface of at least one of said plurality of heat transfer surfaces to generate a steam vapor; (h) discharging at least some of said brine as an evaporator blowdown stream; (i) slightly compressing said steam vapor to produce a compressed steam vapor; (j) directing said compressed steam vapor to a second surface of at least one of said plurality of heat transfer surfaces to condense said compressed steam vapor and to form a distillate; (k) collecting said distillate; (l) introducing said distillate into a boiler, to produce (i) steam, (ii) a boiler blowdown stream, said boiler blowdown stream comprising water and residual dissolved solids. (iii) adding said boiler blowdown stream to said evaporator feedwater prior to the step of heating said evaporator feedwater; (m) injecting said steam in injection wells to fluidize oil present in a selected geological formation, to produce an oil and water mixture for collection at a production well; (n) gathering said oil and water mixture. 2. The method as set forth in claim 1, wherein said evaporator feedwater further comprises at least some non-hydroxide alkalinity, further comprising prior to heating said evaporator feedwater, lowering the pH of said evaporator feedwater by the addition of acid thereto, so as to produce at least some free carbon dioxide, in order to remove at least some non-hydroxide alkalinity from said evaporator feedwater. 3. The method as set forth in claim 1, further comprising cooling said evaporator distillate prior to feeding of said distillate to a boiler. 4. The method as set forth in claim 3, further comprising removing at least some residual solutes from said distillate to produce a substantially solute free boiler feedwater stream. 5. The method as set forth in claim 4, wherein said method further comprises heating said substantially solute free treated boiler feedwater stream before introducing said stream into said boiler. 6. The process as set forth in claim 1, wherein during concentrating said evaporator feedwater, the pH of said concentrated heated brine circulating in said evaporator is maintained to at least 10. 5. 7. The process as set forth in claim 1, wherein during concentrating said evaporator feedwater, the pH of said concentrated heated brine circulating in said evaporator is maintained to between about 11 and about 12. 8. The process as set forth in claim 1, wherein during concentrating said evaporator feedwater, the pH of said concentrated heated brine circulating in said evaporator is maintained to 12 or above. 9. The process as set forth in claim 1, or in claim 4, wherein said evaporator feedwater further comprises calcium, and wherein a seeded-slurry is maintained for preferential precipitation of said calcium to said seeds rather than to said heat transfer surfaces of said evaporator. 10. The process as set forth in claim 6, or in claim 7, wherein pH is maintained by the addition of sodium hydroxide. 11. The process as set forth in claim 2, wherein lowering the pH of said evaporator feedwater is accomplished by addition of sulfuric acid or hydrochloric acid. 12. The process as set forth in claim 1, wherein said evaporator is a falling-film type evaporator. 13. The process as set forth in claim 1, wherein said evaporator is a forced-circulation type evaporator. 14. The process as set forth in claim 12 or in claim 13, wherein said heat transfer surfaces are tubular. 15. The process as set forth in claim 14, wherein said evaporator feedwater is concentrated in the interior of said tubular heat transfer surfaces. 16. The process as set forth in claim 12 or in claim 13, wherein said evaporator comprises a mechanical vapor recompression evaporator. 17. The process as set forth in claim 1, further comprising returning said boiler blowdown stream to said evaporator feedwater. 18. The process as set forth in claim 1, wherein said distillate comprises water and residual solutes. further comprising removing said residual solutes from said distillate in an electrodeionization treatment unit to produce (a) a substantially solute free distillate for feed to said boiler, and (2) a solute containing reject stream. 19. The process as set forth in claim 18, further comprising returning said electrodeionization reject stream to said evaporator feedwater stream for treatment in said evaporator. 20. The process as set forth in claim 1, further comprising the step of injecting said evaporator blowdown stream in a deep-well. 21. The process as set forth in claim 1, further comprising the step of treating said evaporator blowdown stream in a crystallizer. 22. The process as set forth in claim 1, further comprising the step of treating said evaporator blowdown stream in a spray dryer, to produce dry solids from said evaporator blowdown stream. 23. The process as set forth in claim 1, further comprising, before heating said evaporator feedwater, removing oil from said evaporator feedwater stream to a selected concentration. 24. The process as set forth in claim 23, wherein the selected concentration of oil in said evaporator feedwater comprises less than about twenty parts per million. 25. The process as set forth in claim 24, further comprising removing residual solutes in said evaporator distillate in an ion exchange resin. 26. The process as set forth in claim 25, 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 to treat said ion exchange regenerant stream in said evaporator. 27. The process as set forth in claim 1, wherein said boiler comprises a packaged boiler. 28. The process as set forth in claim 1, wherein said boiler comprises a once-through steam generator which produces about 80% quality steam. 29. The process as set forth in claim 28, further comprising, after said once through steam generator, separating steam and liquid from said about 80% quality steam, to produce a steam stream having substantially 100% quality. 30. The process as set forth in claim 29, wherein said 100% steam quality stream is injected in said injection wells. 31. The process as set forth in claim 29, wherein said step of separating said about 80% steam comprises producing a liquid stream containing dissolved solutes, and wherein said liquid stream is flashed to produce a still further concentrated liquid containing dissolved solutes. 32. The process as set forth in claim 31, further comprising adding said still further concentrated liquid containing dissolved solutes from flashing to said evaporator feedwater.