Method for selective treatment of microbiologically influenced corrosion (MIC) of metal surfaces

Patent metadata

Field	Value
Publication number	US-9732369-B2
Application number	US-201514809444-A
Country	US
Kind code	B2
Filing date	Jul 27, 2015
Priority date	Jul 27, 2015
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

Provided is a multi-phase process for conditionally treating MIC by evaluating whether MIC-correlating conditions exist, the degree of MIC, if present, and then applying a concomitant MIC-mitigating treatment which is adjusted in its degree of aggressiveness in proportion to MIC severity. The disclosed methodology allows, in part, for the continuous or periodic monitoring and assessment of MIC risk in petroleum-based equipment (e.g., pipeline) and the administering of a treatment that corresponds to the level of severity of the MIC resulting in a more fine-tuned, localized, and cost-effective treatment.

First claim

What is claimed is:

1. A method for selectively mitigating Microbial Influenced Corrosion (MIC) of a site of interest comprising:
(a) determining whether suitable conditions for MIC exist at the site of interest;
(b) if so, monitoring the degree of MIC severity at the site of interest;
(c) administering an MIC treatment to the site of interest that corresponds to the degree of MIC severity;

wherein the determining step (a) comprises:
(i) measuring the temperature at the site of interest, wherein if the temperature is greater than a threshold temperature, then suitable conditions for MIC do not exist and treatment is not required, but if the temperature is less than the threshold temperature, then proceed to
(ii) measuring the pH at the site of interest, wherein if the pH falls outside a threshold pH range, then suitable conditions for MIC do not exist and treatment is not required, but if the pH falls within a threshold pH range, then proceed to
(iii) measuring the flow rate at the site of interest and the water drop-out, wherein if the flow rate is greater than a threshold flow rate and there is no water drop-out, then suitable conditions for MIC do not exist and treatment is not required, but if the flow rate is less than the threshold flow rate and there is water drop-out, then proceed to
(iv) measuring the planktonic cell count at the site of interest, wherein if planktonic cell count is below a threshold cell count, then suitable conditions for MIC do not exist and treatment is not required, but if the planktonic cell count is above a threshold cell count, then proceed to
(v) determining the microbial community at the site of interest, wherein if less than a threshold percent of the total microbial population comprises species associated with MIC, then suitable conditions for MIC do not exist and treatment is not required, but if more than the threshold percent of the total microbial population comprises species associated with MIC, then proceed to the monitoring step (b) to determine the degree of MIC, and the corresponding treatment of step (c), and

wherein the monitoring step (b) comprises:
(i) measuring the biofilm biomass at the site of interest, wherein if the biofilm biomass is below a threshold biomass, then a first-level MIC treatment is administered to the site of interest, but if the measured biofilm biomass is above the threshold biomass, then proceed to
(ii) detecting the site of interest for localized corrosion, wherein if there is no localized corrosion at the site of interest, then a second-level MIC treatment is administered to the site of interest, but if there is localized corrosion, then proceed to
(iii) measuring the level of corrosion of one or more coupons, wherein if the level of corrosion is below a threshold level, then a third-level MIC treatment is administered to the site of interest, but if the level of corrosion is above the threshold level, then proceed to
(iv) detecting the presence of corrosion debris at the site of interest, wherein if no debris is present, then the third-level MIC treatment is administered, but if debris is detected then a fourth-level MIC treatment is administered,
wherein the aggressiveness of the first-level MIC treatment is lower than the second-level MIC treatment, which is lower than the third-level MIC treatment, which is lower than the fourth-level MIC treatment.

2. The method of claim 1 , wherein for the administering step (c) the MIC treatment comprises a combination of biocide application and pigging.

3. The method of claim 1 , wherein the threshold temperature of (i) is 60° C.

4. The method of claim 1 , wherein the threshold temperature of (i) is 90° C.

5. The method of claim 1 , wherein the threshold pH range of (ii) is a pH of 4-12.

6. The method of claim 1 , wherein the threshold flow rate of (iii) is 10 meters per second (m/s).

7. The method of claim 1 , wherein the threshold cell count is 10 3 cells per ml if the cell count is determined by an ATP assay.

8. The method of claim 1 , wherein the threshold cell count is 10 2 cells per ml if the cell count is determined by an SD assay.

9. The method of claim 1 , wherein the threshold cell count is 10 3 cells per ml if the cell count is determined by an qPCR assay.

10. The method of claim 1 , wherein the threshold biomass of (i) is 10 4 cells/cm 2 if measured by an ATP assay, or 10 2 cells/cm 2 if measured by an SD assay, or 10 4 cells/cm 2 if measured by a qPCR assay.

11. The method of claim 1 , wherein the localized corrosion of (ii) comprises corrosion-related pitting.

12. The method of claim 1 , wherein the threshold level of corrosion of (iii) is 1 milli-inch per year.

13. The method of claim 1 , wherein the first-level treatment comprises administering a biocide to provide a final concentration at the site of interest of 5-1000 ppm over the course of 10 minutes to 10 hours every 14-28 days in combination with pigging at least twice per year.

14. The method of claim 1 , wherein the second-level treatment comprises administering a biocide to provide a final concentration at the site of interest of 5-1000 ppm over the course of 10 minutes to 10 hours every 7-14 days in combination with pigging every 4-8 weeks.

15. The method of claim 1 , wherein the third-level treatment comprises administering a biocide to provide a final concentration at the site of interest of 5-1000 ppm over the course of 10 minutes to 10 hours every 3-7 days in combination with pigging every 2-4 weeks.

16. The method of claim 1 , wherein the fourth-level treatment comprises administering a biocide to provide a final concentration at the site of interest of 5-1000 ppm over the course of 10 minutes to 10 hours every 3-7 days in combination with pigging every week.

17. The method of claim 1 , wherein the MIC is caused by a bacterial biofilm deposited on the surface of the site of interest.

18. The method of claim 17 , wherein the bacterial biofilm is formed by anaerobic bacteria.

19. The method of claim 18 , wherein the anaerobic bacteria are selected from the group consisting of sulfate reducing bacteria, iron oxidizing bacteria, sulfur oxidizing bacteria, nitrate reducing bacteria, methanogens, and acid producing bacteria.

20. The method of claim 19 , wherein the sulfate reducing bacteria is of the genera Desulfuvibrio, Desulfotomaculum, Desulfosporomusa, Desulfosporosinus, Desulfobacter, Desulfobacterium, Desulfobacula, Desulfobotulus, Desulfocella, Desulfococcus, Desulfofaba, Desulfofrigus, Desulfonema, Desulfosarcina, Desulfospira, Desulfotalea, Desulfotignum, Desulfobulbus, Desulfocapsa, Desulfofustis, Desulforhopalis, Desulfoarculus, Desulfobacca, Desulfomonile, Desulfotigmum, Desulfohalobium, Desulfomonas, Desulfonatronovibrio, Desulfomicrobium, Desulfonatronum, Desulfacinum, Desulforhabdus, Syntrophobacter, Syntrophothermus, Thermaerobacter , and Thermodesulforhabdus.

21. The method of claim 20 , wherein the sulfate reducing bacteria is of the genera Desulfuvibrio.

22. The method of claim 1 , wherein the site of interest is a metal surface of equipment for refining, storing, or transporting of crude or processed oil.

23. The method of claim 1 , wherein the the site of interest is a metal surface of equipment for refining, storing, or transporting of natural gas.

24. The method of claim 1 , wherein the biocide is selected from the group consisting of germicides, antibiotics, antibacterials, antivirals,

Assignees

• Pilloni Giovanni
• Enning Dennis R
• Exxonmobil Res & Eng Co

Inventors

• Pilloni Giovanni
• Enning Dennis R

Classifications

• B05D3/002

  Pretreatement · CPC title

• B05D7/222

  of pipes · CPC title

• C09K8/54

  Compositions for in situ inhibition of corrosion in boreholes or wells · CPC title

• F16L58/04

  Coatings characterised by the materials used (F16L58/16 takes precedence) · CPC title

• C23F15/00

  Other methods of preventing corrosion or incrustation · CPC title