Reduced Corrosion Iron Sulfide Scale Removing Fluids

• US 20190040300A1
• Filed: 08/07/2017
• Published: 02/07/2019
• Est. Priority Date: 08/07/2017
• Status: Active Grant

• Current Assignee: Saudi Arabian Oil Company (Government of Saudi Arabia)
• Original Assignee: Saudi Arabian Oil Company (Government of Saudi Arabia)
• Inventors: Sun, Hejian, Li, Leiming, Liang, Feng
• Granted Patent: US 10,457,850 B2
• Time in Patent Office: Days
• CPC Class Codes: C09K 2208/20 Hydrogen sulfide elimination
• CPC Class Codes: C09K 2208/32 Anticorrosion additives
• CPC Class Codes: C09K 8/532 Sulfur
• CPC Class Codes: C09K 8/54 Compositions for in situ inhibition of corrosion in boreholes or wells
• CPC Class Codes: C23G 1/088 solutions containing organic acids
• CPC Class Codes: E21B 37/06 using chemical means for preventing or limiting , e.g. eliminating, the deposition of paraffins or like substances

Abstract

A low-corrosivity composition suitable for dissolving scale on metals. The scale includes iron sulfide scale. The composition includes an aqueous hydrogen peroxide solution comprising hydrogen peroxide; and an acidic solution comprising at least one acid, where the hydrogen peroxide and acid are present at concentrations such that the hydrogen peroxide does not break down to form visible bubbles at about room temperature, where the hydrogen peroxide and acid are present at concentrations such that iron sulfide scale is removed from a metal with iron sulfide scale, after the composition contacts the metal and iron sulfide scale at an elevated temperature greater than room temperature, and where the hydrogen peroxide and acid are present at concentrations such that pitting is not caused on the metal, the metal comprising carbon steel.

Claims

1. A low-corrosivity composition suitable for dissolving scale on metals, where the scale comprises iron sulfide scale, the composition comprising:

an aqueous hydrogen peroxide solution comprising hydrogen peroxide; and

an acidic solution comprising at least one acid, where the hydrogen peroxide and acid are present at concentrations such that the hydrogen peroxide does not break down to form visible bubbles at about room temperature,

where the hydrogen peroxide and acid are present at concentrations such that iron sulfide scale is removed from a metal with iron sulfide scale, after the composition contacts the metal and iron sulfide scale at an elevated temperature greater than room temperature, and

where the hydrogen peroxide and acid are present at concentrations such that pitting is not caused on the metal, the metal comprising carbon steel.

2. The composition according to claim 1, further comprising a hydrogen peroxide stabilizer.

3. The composition according to claim 2, where the hydrogen peroxide stabilizer is selected from the group consisting of:

stannates;

acetanilide;

phenol;

pyrophosphates;

nitrate;

organophosphonates; and

combinations thereof.

4. The composition according to claim 3, where the hydrogen peroxide stabilizer comprises sodium stannate.

5. The composition according to claim 1, where the acidic solution comprises acetic acid.

6. The composition according to claim 1, where the composition further comprises a component selected from the group consisting of:

a viscosifying agent;

a chelating agent;

a surfactant;

a foaming agent; and

combinations thereof.

7. The composition according to claim 5, where the hydrogen peroxide is present at about between 0.5% and about 1.5% by weight of the composition and where the acetic acid is present at about between 0.25% and about 2.5% by weight of the composition.

8. The composition according to claim 1, where the elevated temperature greater than room temperature is at least about 95°

C.

9. The composition according to claim 8, where corrosion to the carbon steel is less than about 0.05 lbs/ft² after about 6 hours of the composition contacting the metal and iron sulfide scale at the elevated temperature.

10. A low-corrosivity method suitable for dissolving scale on metals, where the scale comprises iron sulfide scale, the method comprising the steps of:

mixing an aqueous hydrogen peroxide solution comprising hydrogen peroxide and an acidic solution comprising at least one acid to form a mixture, where the hydrogen peroxide and acid are present at concentrations such that the hydrogen peroxide does not break down to form visible bubbles at about room temperature;

applying the mixture to a metal comprising iron sulfide scale; and

promoting contact between the mixture and the metal comprising iron sulfide scale at an elevated temperature greater than room temperature such that at least a portion of the iron sulfide scale is removed from the metal after the composition contacts the metal and iron sulfide scale at the elevated temperature greater than room temperature, where the hydrogen peroxide and acid are present at concentrations such that pitting is not caused on the metal, the metal comprising carbon steel.

11. The method according to claim 10, further comprising the step of adding a hydrogen peroxide stabilizer.

12. The method according to claim 11, where the hydrogen peroxide stabilizer is selected from the group consisting of:

stannates;

acetanilide;

phenol;

pyrophosphates;

nitrate;

organophosphonates; and

combinations thereof.

13. The method according to claim 12, where the hydrogen peroxide stabilizer comprises sodium stannate.

14. The method according to claim 10, where the acidic solution comprises acetic acid.

15. The method according to claim 10, further comprising the step of adding at least one component selected from the group consisting of:

a viscosifying agent;

a chelating agent;

a surfactant;

a foaming agent; and

combinations thereof.

16. The method according to claim 14, where the hydrogen peroxide is present at about between 0.5% and about 1.5% by weight of the mixture and where the acetic acid is present at about between 0.25% and about 2.5% by weight of the mixture.

17. The method according to claim 10, where the elevated temperature greater than room temperature is at least about 95°

C.

18. The method according to claim 17, where corrosion to the carbon steel is less than about 0.05 lbs/ft² after about 6 hours of promoting contact.

19. The method according to claim 10, where the step of applying the mixture to a metal comprising iron sulfide scale is performed in a wellbore used in hydrocarbon production operations.