Iron sulfide removal in oilfield applications

Patent metadata

Field	Value
Publication number	US-2018340113-A1
Application number	US-201815990329-A
Country	US
Kind code	A1
Filing date	May 25, 2018
Priority date	May 26, 2017
Publication date	Nov 29, 2018
Grant date	—

Abstract

Dissolving iron sulfide on the carbon steel tubing to yield chelated iron is achieved by treating the carbon steel tubing with a composition including an iron chelant and an additive. The additive includes at least one of an oxidizing agent and a base. A weight ratio of the iron chelant to the additive is in a weight range of 50:1 to 5:1.

First claim

1 . A composition for dissolving iron sulfide, the composition comprising:
an iron chelant; and an additive, wherein the additive comprises at least one of:
an oxidizing agent; and
a base,
wherein a weight ratio of the iron chelant to the additive is in a range of 50:1 to 5:1.

2 . The composition of claim 1 , wherein a concentration of the iron chelant in the composition is in a range of 10 wt % to 80 wt %.

3 . The composition of claim 1 , wherein the additive comprises an oxidizing agent.

4 . The composition of claim 3 , wherein a concentration of the oxidizing agent in the composition is in a range of 0.05 wt % to 15 wt %.

5 . The composition of claim 1 , wherein additive comprises an oxidizing agent, and the oxidizing agent comprises at least one of potassium permanganate, ammonium nitrate, sodium nitrate, sodium bromate, sodium hypochlorite, sodium nitrite, sodium bicarbonate, potassium bicarbonate, ammonium carbonate, ammonium bicarbonate, and iodine.

6 . The composition of claim 1 , wherein the additive comprises a base, and a concentration of the base in the composition is in a range of 1 wt % to 60 wt %.

7 . The composition of claim 6 , wherein the base comprises a strong base, a medium base, or a weak base.

8 . The composition of claim 7 , wherein the base comprises a strong base, and the strong base comprises at least one of potassium hydroxide and sodium hydroxide.

9 . The composition of claim 7 , wherein the base comprises a medium base, and the medium base comprises at least one of potassium carbonate, sodium carbonate, potassium bicarbonate, ammonium carbonate, and ammonium bicarbonate.

10 . The composition of claim 1 , wherein the iron chelant comprises at least one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, tetrasodium glutamate diacetate, tetrakis(hydroxymethyl)phosphonium sulfate, nitrilotriacetic acid, citrate, and pyrophosphate.

11 . The composition of claim 1 , wherein the composition is free of hydrochloric acid.

12 . The composition of claim 1 , wherein a pH of the composition is in a range of 3 to 14.

13 . A method of treating carbon steel tubing in a subterranean formation, the method comprising:
providing a composition comprising an iron chelant and an additive to the carbon steel tubing, the additive comprising at least one of an oxidizing agent and a base; contacting the carbon steel tubing with the composition for a length of time; and dissolving iron sulfide on the carbon steel tubing with the composition to yield chelated iron.

14 . The method of claim 13 , wherein a weight ratio of the iron chelant to the additive is in a range of 50:1 to 5:1.

15 . The method of claim 13 , wherein dissolving the iron sulfide does not result in formation of hydrogen sulfide.

16 . The method of claim 13 , wherein dissolving the iron sulfide comprises dissolving 5 wt % to 100 wt % percent of the iron sulfide.

17 . The method of claim 13 , wherein the length of time is in a range of 4 hours to 72 hours.

18 . The method of claim 13 , wherein, after the length of time, corrosion of the carbon steel tubing is less than 0.05 lb/ft 2 .

19 . The method of claim 13 , comprising, after the length of time, removing the composition from the subterranean formation.

Assignees

• Saudi Arabian Oil Co

Inventors

• Chen Tao
• Wang Qiwei
• Chang Fakuen Frank

Classifications

• C09K8/532 Primary

  Sulfur · CPC title

• C09K2208/32

  Anticorrosion additives · CPC title

• C09K8/54

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

• C09K8/528

  inorganic depositions, e.g. sulfates or carbonates · CPC title

• C09K2208/20

  Hydrogen sulfide elimination · CPC title