METHOD OF CONTROLLING CORROSION RATE IN DOWNHOLE ARTICLE, AND DOWNHOLE ARTICLE HAVING CONTROLLED CORROSION RATE

• US 20130032357A1
• Filed: 08/05/2011
• Published: 02/07/2013
• Est. Priority Date: 08/05/2011
• Status: Active Grant

• Current Assignee: Baker Hughes Holdings LLC (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Mazyar, Oleg A., Johnson, Michael, Gaudette, Sean
• Granted Patent: US 9,057,242 B2
• Time in Patent Office: Days
• US Class Current: 166/376
• CPC Class Codes: C25F 3/02 Etching
• CPC Class Codes: C25F 7/00 Constructional parts, or assemblies thereof, of cells for electrolytic removal of material from objects for both electrolytic coating and removal C25D; Servicing or operating
• CPC Class Codes: E21B 29/00 Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground
• CPC Class Codes: E21B 33/12 Packers; Plugs used for cementing E21B33/134, E21B33/16
• CPC Class Codes: E21B 34/063 Valve or closure with destructible element, e.g. frangible disc E21B34/103 takes precedence

Abstract

A method of removing a downhole assembly comprises contacting, in the presence of an electrolyte, a first article comprising a first material and acting as an anode, and a second article comprising a second material having a lower reactivity than the first material and acting as a cathode, the downhole assembly comprising the first article in electrical contact with the second article, wherein at least a portion of the first article is corroded in the electrolyte.

Claims

1. A method of removing a downhole assembly, comprising

contacting, in the presence of an electrolyte,

a first article comprising a first material and acting as an anode, and

a second article comprising a second material having a lower reactivity than the first material and acting as a cathode,

the downhole assembly comprising the first article in electrical contact with the second article,

wherein at least a portion of the first article is corroded in the electrolyte.

2. The method of claim 1, wherein the first material comprises a magnesium alloy.

3. The method of claim 1, wherein the first article has a non-metallic coating on a surface thereof.

4. The method of claim 3, wherein the coating comprises a soluble glass, a soluble polymer, or a metal oxide or hydroxide coating.

5. The method of claim 3, wherein the non-metallic coating is magnesium hydroxide.

6. The method of claim 3, wherein the non-metallic coating is removed by application of an electric potential to establish electrical contact between the first and second articles.

7. The method of claim 1, wherein the second material comprises steel, tungsten, chromium, nickel, copper, iron, aluminum, zinc, alloys thereof, or a combination comprising at least one of the foregoing.

8. The method of claim 1, wherein the first article is a controlled electrolytic material (CEM) ball or fracture plug.

9. The method of claim 1, wherein the second article is a ball seat.

10. The method of claim 1, wherein the first article comprises:

a corrodible core comprising the first material and at least partially penetrating the first article, and

a non-corrodible surrounding structure comprising the second material,

wherein only the core is corroded.

11. The method of claim 1, wherein the first article comprises:

a non-corrodible core comprising the second material and at least partially penetrating the first article, and

a corrodible surrounding structure comprising the first material,

wherein only the surrounding structure is corroded.

12. The method of claim 1, wherein the electrolyte is water, brine, acid, or a combination comprising at least one of the foregoing.

13. A method of producing an electrical potential in a downhole assembly, comprising

contacting, with an electrolyte,

a first article, the first article comprising a first material and acting as an anode, and

a second article, the second article comprising a second material having a lower reactivity than the material of the first article and acting as a cathode, with a conductive element to form a circuit.

14. The method of claim 13, wherein the first material comprises a magnesium alloy having less than or equal to about 0.5 weight percent of nickel.

15. The method of claim 13, wherein the electrolyte is water, brine, an acid, or a combination comprising at least one of the foregoing.

16. The method of claim 13, wherein the second material comprises steel, tungsten, chromium, nickel, cobalt, copper, iron, aluminum, zinc, alloys thereof, or a combination comprising at least one of the foregoing.

17. The method of claim 13, further comprising corroding the first article in the electrolyte.

18. A downhole assembly, comprising:

a first article comprising a first material and acting as an anode, and

a second article comprising a second material having a lower reactivity than the first material and acting as a cathode,

the first and second articles being electrically connected by a conductive element to form a circuit,

wherein in the presence of an electrolyte, the downhole assembly produces an electrical potential, and at least a portion of the first article is corroded.

19. The article of claim 18, wherein the first material comprises magnesium, and the second material comprises steel, tungsten, chromium, nickel, cobalt copper, iron, aluminum, zinc, alloys thereof, or a combination comprising at least one of the foregoing.

20. The article of claim 18, wherein the first article is a ball, and the second article is a ball seat.