Insulative coating processes for electromagnetic telemetry mandrels

Patent metadata

Field	Value
Publication number	US-9739099-B2
Application number	US-201314345548-A
Country	US
Kind code	B2
Filing date	Sep 30, 2013
Priority date	Oct 5, 2012
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

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 mandrel, comprising:
an elongate body having a first end and a second end;
electrical insulation applied to at least a portion of the elongate body, the electrical insulation comprising a buffer layer over an outer radial surface of the elongate body, a bond coat bonded to the buffer laver, and an electrical isolation layer applied on top of the bond coat; and
a first sealant layer applied to the electrical isolation layer.

2. The mandrel of claim 1 , further comprising a second sealant layer applied to the first sealant layer.

3. The mandrel of claim 2 , 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.

4. The mandrel of claim 2 , wherein the second sealant layer is applied to the first sealant layer following heat treatment of the mandrel.

5. The mandrel of claim 4 , wherein the second sealant layer is applied to the first sealant layer prior to the mandrel reaching room temperature.

6. The mandrel of claim 1 , wherein the first and second ends are coupled to uphole and downhole drill string sections, respectively.

7. The mandrel of claim 6 , wherein the electrical insulation is applied to a reduced-diameter portion of the elongate body.

8. The mandrel of claim 1 , wherein the bond coat comprises a material selected from the group consisting of a nickel-chromium alloy, molybdenum, a nickel-aluminum composite, aluminum bronze, pre-alloyed nickel aluminum, and a zinc-based alloy.

9. The mandrel 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.

10. The mandrel of claim 9 , wherein the electrical isolation layer is applied to a thickness of about 0.030 inches.

11. The mandrel of claim 1 , wherein the buffer layer comprises austenitic nickel-chromium-based alloy.

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

• B05D7/582

  all layers being cured or baked together · 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

• E21B17/003 Primary

  with electrically conducting or insulating means (E21B17/028 and E21B17/023 take precedence) · CPC title