Reduced corrosion iron sulfide scale removing fluids

• US 10,457,850 B2
• Filed: 08/07/2017
• Issued: 10/29/2019
• 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
• Primary Examiner(s): Bhushan, Kumar R
• Application Number:
  US15/670,826
• Publication Number:
  US 20190040300A1
• Time in Patent Office: 813 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 metal, where the scale comprises iron sulfide scale, the composition consisting of:

an aqueous hydrogen peroxide solution comprising hydrogen peroxide, where the hydrogen peroxide is present at about between 0.5% and about 1.5% by weight of the composition; and

an acidic solution comprising at least one acid, where the acidic solution comprises acetic acid present at about between 0.25% and about 2.5% by weight of the composition, 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 the iron sulfide scale is removed from the 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, and where the balance of the composition is at least about 90 weight % water to form a dilute, low-corrosivity solution mixture.

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

C.

3. The composition according to claim 2, 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.

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

mixing the low-corrosivity composition of claim 1 to form a mixture;

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

promoting contact between the mixture and the metal comprising iron sulfide scale at the elevated temperature greater than room temperature such that 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.

5. The method according to claim 4, further comprising the step of adding a hydrogen peroxide stabilizer.

6. The method according to claim 5, where the hydrogen peroxide stabilizer is selected from the group consisting of:

stannates;

acetanilide;

phenol;

pyrophosphates;

nitrate;

organophosphonates; and

combinations thereof.

7. The method according to claim 6, where the hydrogen peroxide stabilizer comprises sodium stannate.

8. The method according to claim 4, 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.

9. The method according to claim 4, where the elevated temperature greater than room temperature is at least about 95°

C.

10. The method according to claim 9, where corrosion to the carbon steel is less than about 0.05 lbs/ft² after about 6 hours of promoting contact.

11. The method according to claim 4, where the step of applying the mixture to the metal comprising iron sulfide scale is performed in a wellbore used in hydrocarbon production operations.