Temperature assessment using dielectric properties of an insulated conductor heater with selected electrical insulation

Patent metadata

Field	Value
Publication number	US-10316644-B2
Application number	US-201414243647-A
Country	US
Kind code	B2
Filing date	Apr 2, 2014
Priority date	Apr 4, 2013
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

A system for assessing one or more temperatures in an opening in a subsurface formation includes an electrical conductor and electrical insulation at least partially surrounding the electrical conductor. The electrical insulation includes magnesium oxide and a ferroelectric material. An electrically conductive sheath at least partially surrounds the electrical insulation. A profile of one or more dielectric properties of the electrical insulation along a length of the electrical insulation is assessed during use to assess a temperature profile with spatial resolution along the length of the electrical insulation.

First claim

What is claimed is:

1. A system for assessing a temperature in an opening in a subsurface formation, comprising:
an electrical conductor;
electrical insulation at least partially surrounding the electrical conductor, the electrical insulation comprising magnesium oxide and a ferroelectric material comprising bismuth titanate, wherein the electrical insulation contains at most 5% by weight of the ferroelectric material; and
an electrically conductive sheath at least partially surrounding the electrical insulation.

2. The system of claim 1 , wherein the electrical insulator comprises at most about 5% by weight of bismuth titanate.

3. The system of claim 1 , wherein the bismuth titanate is doped with niobium.

4. The system of claim 1 , wherein the electrical insulation comprises a dielectric constant that increases by a factor of at least about 1.5 for every degree Celsius increase in temperature in a desired temperature range.

5. The system of claim 1 , wherein the electrical conductor and the electrical insulation comprise a length of at least about 10 m.

6. The system of claim 1 , wherein the system is located in a wellbore in a subsurface formation.

7. The system of claim 1 , wherein the system is located in a wellbore in a subsurface formation and at least one heater for providing heat to the subsurface formation is located in the wellbore.

8. The system of claim 1 , wherein the electrical conductor and the electrically conductive sheath are used to assess the dielectric properties of the electrical insulation during use.

9. A method for assessing a temperature in an opening in a subsurface formation, comprising:
assessing a profile of one or more dielectric properties with spatial resolution along a length of an insulated conductor located in the opening, wherein the insulated conductor comprises:
an electrical conductor;
electrical insulation at least partially surrounding the electrical conductor, the electrical insulation comprising magnesium oxide and a ferroelectric material comprising bismuth titanate, wherein the electrical insulation comprises at most 5% by weight of the ferroelectric material;
an electrically conductive sheath at least partially surrounding the electrical insulation; and
assessing a temperature profile with spatial resolution along the length of the insulated conductor based on the assessed profile of the one or more dielectric properties.

10. The method of claim 9 , wherein the electrical insulator comprises at most about 5% by weight of bismuth titanate.

11. The method of claim 9 , wherein the bismuth titanate is doped with niobium.

12. The method of claim 9 , wherein at least one of the dielectric properties comprises a dielectric constant.

13. The method of claim 9 , wherein the electrical insulation comprises a dielectric constant that increases by a factor of at least about 1.5 for every degree Celsius increase in temperature in a desired temperature range.

14. The method of claim 9 , further comprising providing heat to the subsurface formation with a heater located in a wellbore in the formation, wherein the insulated conductor is located in the wellbore proximate the heater.

15. The method of claim 9 , further comprising providing electrical power to at least a portion of the insulated conductor, and providing at least some heat to the subsurface formation from the portion of the insulated conductor.

16. The method of claim 9 , further comprising using the electrical conductor and the electrically conductive sheath to assess the dielectric properties of the electrical insulation.

17. The method of claim 9 , further comprising monitoring a trend in the profile of at least one dielectric property to assess a difference between increase in temperature and decrease in temperature for a range of values of the dielectric property.

18. The method of claim 9 , wherein assessing the temperature profile comprises comparing temperature dependence data of the dielectric properties to the assessed profile of the one or more dielectric properties.

Assignees

• Shell Oil Co

Inventors

• Harris Christopher Kelvin
• De St Remey Edward Everett
• Thompson Stephen Taylor

Classifications

• G01K2213/00

  Temperature mapping · CPC title

• G01K7/343

  the dielectric constant of which is temperature dependant · CPC title

• E21B36/04 Primary

  using electrical heaters · CPC title

• E21B47/07 Primary

  Temperature · CPC title

• E21B47/065 Primary

  Fixed Constructions · mapped topic