Process for recovering oil and treating resulting produced water with ceramic membranes

1. A method of recovering oil from an oil well and treating resulting produced water, comprising:

recovering an oil-water mixture from the oil well;

separating the produced water from the oil-water mixture;

directing the produced water to and through a ceramic membrane having a porous structure;

filtering the produced water with the ceramic membrane to produce a permeate stream and a retentate stream;

cleaning the ceramic membrane in online and offline modes comprising:

a. in the online mode periodically backflushing the ceramic membrane with an aqueous media having a pH of 13 or greater and a temperature of 60° C. or greater:

b. in the offline mode, backpulsing or statically cleaning the ceramic membrane by performing:

i. one or more clean-in-place operations utilizing an aqueous alkaline media having a pH of 13 or greater and a temperature of 60° C. or greater;

ii. one or more clean-in-place operations utilizing an aqueous acidic media containing approximately 0.25% to approximately 2.0% dissolved citric acid; and

iii. one or more clean-in-place operations utilizing a liquid hydrocarbon solution.

2. The method of claim 1 wherein the aqueous acidic media contains approximately 0.25% to approximately 2.0% dissolved citric acid.

3. The method of claim 1 wherein the time period for cleaning the ceramic membrane in the online mode is approximately 5 to approximately 30 minutes and wherein the time period for cleaning the ceramic membrane in the offline mode is approximately 20 minutes to approximately 24 hours.

4. The method of claim 1 including backpulsing the aqueous alkaline media, aqueous acidic media, or the liquid hydrocarbon solution from a permeate side through the ceramic membrane to a retentate side of the ceramic membrane; and soaking the ceramic membrane in the aqueous alkaline media, aqueous acidic media, or the liquid hydrocarbon solution.

5. The method of claim 1 including removing free oil and emulsified oil from the produced water with the ceramic membrane.

6. The method of claim 1 including initiating cleaning the ceramic membrane when the permeability of the ceramic membrane is less than 20% of initial clean water permeability.

7. The method of claim 1 including initiating cleaning by online backflushing at a frequency of approximately once per 4 hours to once per 48 hours.

8. The method of claim 1 including online backflushing with an aqueous alkaline media containing approximately 0.40% wt. to approximately 10.0% wt. of dissolved sodium hydroxide.

9. The method of claim 8 including heating the aqueous alkaline media to a temperature of approximately 90° C. to approximately 105° C. and backflushing the ceramic membrane with the heated aqueous alkaline media.

10. The method of claim 1 wherein the offline clean-in-place cleaning of the ceramic membrane is conducted in a crossflow mode.

11. The method of claim 1 wherein the offline clean-in-place cleaning of the ceramic membrane is conducted in a static or soaking mode.

12. The method of claim 1 wherein the clean-in-place aqueous alkaline media includes approximately 0.40% wt. to approximately 10.0% wt. of dissolved sodium hydroxide.

13. The method of claim 1 wherein the liquid hydrocarbon clean-in-place media includes one or more of the compounds xylene, toluene, benzene, diluents, or petroleum distillates.

14. The method of claim 13 wherein the liquid hydrocarbon clean-in-place media is neat xylene.

15. The method of claim 1 wherein in the offline mode the method includes soaking the ceramic membrane with the liquid hydrocarbon solution.

16. The method of claim 1 wherein after cleaning the ceramic membrane with the liquid hydrocarbon solution, the method includes rinsing the ceramic membrane with a water-miscible liquid organic.

17. The method of claim 16 wherein the water-miscible liquid organic comprises acetone.

18. A method of recovering oil from an oil well and treating resulting produced water, comprising:

recovering an oil-water mixture from the oil well;

separating the produced water from the oil-water mixture;

directing the produced water to and through a ceramic membrane having a porous structure;

filtering the produced water with the ceramic membrane to produce a permeate stream and a retentate stream;

cleaning the ceramic membrane in online and offline modes comprising:

a. in the online mode periodically backflushing the ceramic membrane with an aqueous media having a pH of 13 or greater and a temperature of 60° C. or greater:

b. in the offline mode, backpulsing or statically cleaning the ceramic membrane by performing:

i. one or more clean-in-place operations utilizing an aqueous alkaline media having a pH of 13 or greater and a temperature of 60° C. or greater;

ii. one or more clean-in-place operations utilizing an aqueous acidic media; and

iii. one or more clean-in-place operations utilizing a liquid hydrocarbon solution;

c. wherein the time period for cleaning the ceramic membrane in the online mode is approximately 5 to approximately 30 minutes and wherein the time period for cleaning the ceramic membrane in the offline mode is approximately 20 minutes to approximately 24 hours.

19. A method of recovering oil from an oil well and treating resulting produced water, comprising:

recovering an oil-water mixture from the oil well;

separating the produced water from the oil-water mixture;

directing the produced water to and through a ceramic membrane having a porous structure;

filtering the produced water with the ceramic membrane to produce a permeate stream and a retentate stream;

cleaning the ceramic membrane in online and offline modes comprising:

a. in the online mode periodically backflushing the ceramic membrane with an aqueous media having a pH of 13 or greater and a temperature of 60° C. or greater:

b. in the offline mode, backpulsing or statically cleaning the ceramic membrane by performing:

i. one or more clean-in-place operations utilizing an aqueous alkaline media having a pH of 13 or greater and a temperature of 60° C. or greater;

ii. one or more clean-in-place operations utilizing an aqueous acidic media; and

iii. one or more clean-in-place operations utilizing a liquid hydrocarbon solution;

c. initiating cleaning the ceramic membrane when the permeability is less than 20% of initial clean water permeability.

20. A method of recovering oil from an oil well and treating resulting produced water, comprising:

recovering an oil-water mixture from the oil well;

separating the produced water from the oil-water mixture;

directing the produced water to and through a ceramic membrane having a porous structure;

filtering the produced water with the ceramic membrane to produce a permeate stream and a retentate stream;

cleaning the ceramic membrane in online and offline modes comprising:

a. in the online mode periodically backflushing the ceramic membrane with an aqueous media having a pH of 13 or greater and a temperature of 60° C. or greater:

b. in the offline mode, backpulsing or statically cleaning the ceramic membrane by performing:

i. one or more clean-in-place operations utilizing an aqueous alkaline media having a pH of 13 or greater and a temperature of 60° C. or greater;

ii. one or more clean-in-place operations utilizing an aqueous acidic media; and

iii. one or more clean-in-place operations utilizing a liquid hydrocarbon clean-in-place media comprising neat xylene.

21. A method of recovering oil from an oil well and treating resulting produced water, comprising:

recovering an oil-water mixture from the oil well;

separating the produced water from the oil-water mixture;

directing the produced water to and through a ceramic membrane having a porous structure;

filtering the produced water with the ceramic membrane to produce a permeate stream and a retentate stream;

cleaning the ceramic membrane in online and offline modes comprising:

a. in the online mode periodically backflushing the ceramic membrane with an aqueous media having a pH of 13 or greater and a temperature of 60° C. or greater:

b. in the offline mode, backpulsing or statically cleaning the ceramic membrane by performing:

i. one or more clean-in-place operations utilizing an aqueous alkaline media having a pH of 13 or greater and a temperature of 60° C. or greater; and

ii. one or more clean-in-place operations utilizing an aqueous acidic media;

c. in the offline mode, soaking the ceramic membrane with a liquid hydrocarbon solution.