METHODS FOR RECLAIMING PRODUCED WATER

Abstract

A method for treating produced water from a fracking operation is disclosed. The produced water is first fed to a compact separator for the removal of suspended materials. This produced water is then treated for dissolved gases and suspended oils before being fed to a crystallizer where salts are separated from the produced water thereby producing fresh water for reuse or other means. Alternatively, the produced water may be fed to a disinfection system and a concentrator depending upon the composition of the produced water.

Claims

1. A method for treating produced water comprising the steps: a) Feeding the produced water to an intensified compact separator wherein suspended materials are removed from the produced water; b) Feeding the produced water to a separation system wherein dissolved gases and suspended oils are separated from the produced water; c) Feeding the produced water to a crystallizer wherein water and salts are separated from the produced water; and d) Recovering the water.

2. The method as claimed in claim 1 wherein the produced water contains 150,000 parts per million dissolved solids.

3. The method as claimed in claim 1 wherein the produced water contains dissolved and dispersed oil.

4. The method as claimed in claim 1 wherein the produced water is recovered from a fracking operation.

5. The method as claimed in claim 1 wherein the intensified compact separator is a gravity separator containing submerged plates.

6. The method as claimed in claim 5 wherein the submerged plates are corrugated.

7. The method as claimed in claim 5 wherein oil droplets are further removed from the produced water by the intensified compact separator.

8. The method as claimed in claim 1 wherein the separation system further removes dissolved gas from the produced water.

9. The method as claimed in claim 8 wherein the separation system is a flotation device.

10. The method as claimed in claim 8 wherein the suspended oils are removed from the separation system by skimming.

11. The method as claimed in claim 1 wherein water and salt are separated in the crystallizer.

12. The method as claimed in claim 11 wherein the salt is present in a brine solution.

13. The method as claimed in claim 11 wherein the brine solution is further crystallized thereby producing salt.

14. The method as claimed in claim 11 wherein fresh water is produced in the crystallizer.

15. The method as claimed in claim 1 wherein the intensified compact separator, separation system and crystallizer are mounted on a skid.

16. The method as claimed in claim 15 wherein the skid is mounted on a vehicle.

17. The method as claimed in claim 1 wherein 3 to 13 gallons per minute of produced water is treated.

18. A method for treating produced water comprising the steps: a) Feeding produced water to an intensified compact separator wherein suspended materials are removed from the produced water; b) Feeding the produced water to a separation system wherein dissolved gases and suspended oils are separated from the produced water; c) Feeding the produced water to a disinfection system wherein bacterial count of the produced water is reduced; d) Feeding the produced water to a concentrator wherein the produced water is concentrated; e) Feeding the produced water to a crystallizer wherein water and salts are separated from the produced water; and f) Recovering the water.

19. The method as claimed in claim 18 wherein the produced water contains 150,000 parts per million dissolved solids.

20. The method as claimed in claim 18 wherein the produced water contains dissolved and dispersed oil.

21. The method as claimed in claim 18 wherein the produced water is recovered from a fracking operation.

22. The method as claimed in claim 18 wherein the intensified compact separator is a gravity separator containing submerged plates.

23. The method as claimed in claim 22 wherein the submerged plates are corrugated.

24. The method as claimed in claim 22 wherein oil droplets are further removed from the produced water by the intensified compact separator.

25. The method as claimed in claim 18 wherein the separation system further removes dissolved gas from the produced water.

26. The method as claimed in claim 25 wherein the separation system is a flotation device.

27. The method as claimed in claim 25 wherein the suspended oils are removed from the separation system by skimming.

28. The method as claimed in claim 18 wherein the disinfection system is oxygen-based.

29. The method as claimed in claim 18 wherein the concentrator uses liquefied nitrogen to concentrate the produced water.

30. The method as claimed in claim 18 wherein water and salt are separated in the crystallizer.

31. The method as claimed in claim 30 wherein the salt is present in a brine solution.

32. The method as claimed in claim 31 wherein the brine solution is further crystallized thereby producing salt.

33. The method as claimed in claim 30 wherein fresh water is produced in the crystallizer.

34. The method as claimed in claim 18 wherein the intensified compact separator, separation system and crystallizer are mounted on a skid.

35. The method as claimed in claim 34 wherein the skid is mounted on a vehicle.

36. The method as claimed in claim 18 wherein 3 to 13 gallons per minute of produced water is treated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG. 1 is a schematic of the process for treating produced water per the invention.

[0049] FIG. 2 is a schematic of an alternative process for treating produced water per the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0050] FIG. 1 is a schematic of a first embodiment of the present invention. Produced water from a fracking operation A is fed through line 1 to the intensified compact separator B. The intensified compact separator B will remove suspended materials from the produced water. The produced water now with the suspended materials removed is fed through line 2 to a nitrogen-based suspended oil and dissolved gases separation unit C.

[0051] The produced water which has suspended materials as well as suspended oil and dissolved gases removed from it is fed from the separation unit C through line 3 to the compact crystallizer D. The compact crystallizer D is in fluid communication with a source of liquefied nitrogen E through line 4. The compact crystallizer D contains two cooling zones. The first zone is present in the compact crystallizer D where the produced water is separated into fresh water and a brine solution from the salt crystals that precipitate out of the produced water. The fresh water and brine solution are fed through line 5 to the second cooling separation zone F which will separate the salt from the brine allowing for recovery of salts through line 6 and fresh water through line 7. The fresh water thus recovered may be used in the fracking operation or may be used in other industrial processes. The salts may be recovered and sold or disposed of in an environmentally responsible manner.

[0052] FIG. 2 is a schematic of the process of FIG. 1 with additional unit operations present therein. Accordingly like unit operations and conveyance means will bear the same number and letter scheme as in FIG. 1.

[0053] In FIG. 2, additional unit operations of oxygen-based disinfection and concentrator are present in the schematic of FIG. 1. The produced water that exits the suspended oil and dissolved gases separation unit C is fed through line 8 to an oxygen-based disinfection unit H which will operate to remove the amount of bacteria present in the produced water.

[0054] The produced water with this lower bacterial count is fed through line 9 to a concentrator G. The concentrator G uses liquefied nitrogen and is in fluid communication with the source of liquefied nitrogen E that supplies the crystallizer D through line 4. The concentrator G will be used to concentrate the produced water when the level of dissolved solids is lower than typical levels expected of produced water. The thus concentrated produced water is fed through line 12 to the crystallizer D.

[0055] Alternatively, the produced water from the concentrator G may be fed through line 10 to the suspended oils and dissolved gases unit C for further treatment. Depending upon the level of dissolved solids and their removal, the produced water may be purified sufficiently to be considered fresh water and this fresh water is fed from the concentrator G through line 13 where it will join with the purified water of line 7 from the separation unit F.

[0056] While this invention has been described with respect to particular embodiments thereof, it is apparent that numerous other forms and modifications of the invention will be obvious to those skilled in the art. The appended claims in this invention generally should be construed to cover all such obvious forms and modifications which are within the true spirit and scope of the invention.