Insulative coating processes for electromagnetic telemetry mandrels

Patent metadata

Field	Value
Publication number	US-9938779-B2
Application number	US-201715652125-A
Country	US
Kind code	B2
Filing date	Jul 17, 2017
Priority date	Oct 5, 2012
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

A process for applying an insulative coating to a mandrel can be used in an electromagnetic telemetry antenna assembly. One process includes applying a bond coat to at least a portion of an outer radial surface of a mandrel; applying an electrical isolation layer to the bond coat; applying a first sealant layer to the electrical isolation layer; and heat treating the mandrel in an oven.

First claim

The invention claimed is:

1. A process for coating a mandrel, the process comprising:
applying electrical insulation to an outer radial surface of the mandrel, the electrical insulation comprising a buffer layer on the outer radial surface, a bond coat bonded to the buffer layer, and an electrical isolation layer on the bond coat;
applying a first sealant layer to the electrical isolation layer; and
heat treating the mandrel in an oven.

2. The process of claim 1 , wherein applying the electrical insulation comprises:
applying the bond coat to the outer radial surface of the mandrel; and
applying the electrical isolation layer on top of the bond coat.

3. The process of claim 2 , further comprising applying the electrical isolation layer by thermal spraying.

4. The process of claim 1 , further comprising applying a second sealant layer to the first sealant layer following heat treating the mandrel in the oven.

5. The process of claim 4 , further comprising applying the second sealant layer to the first sealant layer prior to the mandrel reaching room temperature.

6. The process of claim 4 , wherein the first and second sealant layers comprise a material selected from the group consisting of an epoxy, a phenolic, a furan, a polymethacrylate, a silicone, a polyester, a polyurethane, a polyvinylester, a wax, phosphoric acid, an aluminum phosphate, a sodium silicate, an ethyl silicate, chromic acid, and any combinations thereof.

7. The process of claim 1 , wherein applying the electrical insulation comprises:
applying the buffer layer to the outer radial surface of the mandrel;
applying the bond coat to the buffer layer; and
applying the electrical isolation layer on top of the bond coat.

8. The process of claim 1 , wherein the electrical isolation layer comprises a material selected from the group consisting of zirconium oxide, aluminum oxide, chromium oxide, titanium oxide, dioxides thereof, baked glass, porcelain, a polymeric material, a resin material (including natural or synthetic resins), plastics, and any composites thereof.

9. The process of claim 1 , further comprising applying the electrical insulation to a thickness of about 0.030 inches.

Assignees

• Halliburton Energy Services Inc

Inventors

• Carter Daniel Patrick
• Hendricks Will Edgar
• Onya Chuka Benjamin

Classifications

• E21B47/13 Primary

  by electromagnetic energy, e.g. radio frequency · CPC title

• E21B47/017

  Protecting measuring instruments · CPC title

• E21B47/01 Primary

  Devices for supporting measuring instruments on drill bits, pipes, rods or wirelines; Protecting measuring instruments in boreholes against heat, shock, pressure or the like · CPC title

• B05D1/08

  Flame spraying · CPC title

• C23C4/02

  Pretreatment of the material to be coated, e.g. for coating on selected surface areas · CPC title