Downhole electrical power generation based on thermo-tunneling of electrons

1. A system for use in a borehole, the system comprising:

a downhole assembly configured to be conveyed into the borehole;

a quantum tunneling thermoelectric generator (QTG) configured to produce electrical power in response to a difference of temperature between a first side of the generator and a second side of the generator, and

a downhole device operated by the electrical power;

wherein a first side of the QTG is configured to be in thermal contact with an interior of the downhole assembly and a second side of the QTG is configured to be in thermal contact with a fluid between the downhole assembly and a wall of the borehole.

2. The system of claim 1 wherein the borehole is a producing borehole, and wherein the downhole device is selected from (i) a flow control device, (ii) a packer, (iii) a choke, (iv) a perforating device, (v) an anchor, (vi) a completion device, and (vii) a production device.

3. The system of claim 1 further comprising:

(i) a downhole assembly configured to include the QTG; and

(ii) a wireline configured to convey the downhole assembly into the borehole.

4. The system of claim 1 further comprising:

(i) a downhole assembly configured to include the QTG; and

(ii) a conveyance device configured to convey the downhole assembly into the borehole wherein the conveyance device selected from (A) a drillstring, and (B) coiled tubing.

5. The system of claim 1 further comprising:

(i) a phase change material enclosed within an insulating container, and

(ii) a thermally conductive element configured to couple the phase change material to the first side of the QTG.

6. The system of claim 1 wherein the device is selected from the group consisting of: (i) a nuclear magnetic resonance device, (ii) a coring device, (iii) a formation fluid sampling device, and (iv) a resistivity measuring device.

7. The system of claim 1 further comprising a cooling device which cools an electronic component downhole.

8. A method of performing operations in a borehole, the method comprising:

conveying a quantum tunneling thermoelectric generator (QTG) into a borehole on a downhole assembly, a first side of the QTG being in thermal contact with an interior of the downhole assembly and a second side of the OTG being in contact with a fluid between the downhole assembly and a wall of the borehole;

producing electrical power in response to a difference of temperature between the first side of the thermoelectric generator and the second-side of the thermoelectric generator; and

operating a downhole device using the electrical power.

9. The method of claim 8 wherein the borehole is a producing borehole, the method further comprising selecting the downhole device from: (i) a flow control device, (ii) a packer, (iii) a choke, (iv) a perforating device, (v) an anchor, (vi) a completion device, and (vii) a production device.

10. The method of claim 8 wherein the QTG is part of a downhole assembly, the method further comprising conveying the downhole assembly into the borehole on a wireline.

11. The method of claim 8 wherein the QTG is part of a bottomhole assembly, the method further comprising conveying the downhole assembly into the borehole on a conveyance device selected from (i) a drilling tubular, and (ii) coiled tubing.

12. The method of claim 11 further comprising:

raising the downhole assembly including a phase change material;

wherein the first side of the QTG comprises an emitter.

13. The method of claim 8 further comprising:

(i) enclosing a phase change material within an insulating container, and

(ii) thermally coupling the phase change material to the first side of the QTG.

14. The method of claim 13 further comprising:

lowering a downhole assembly including the phase change material into the borehole;

wherein the first side of the QTG comprises a collector.

15. The method of claim 8 wherein operating the device further comprises operating at least one of: (i) a nuclear magnetic resonance device, (ii) a coring device, (iii) a formation fluid sampling device, and (iv) a resistivity measuring device.

16. The method of claim 8 further comprising using a cooling device for cooling an electronic component downhole.

17. A method of conducting operations in a borehole, the method comprising:

conveying a quantum tunneling thermoelectric generator (QTG) into the borehole;

coupling a phase-change material to only a first side of the QTG in a first mode of operation and coupling the phase-change material to only a second side of the QTG in a second mode of operation;

using a temperature difference between the first side of the QTG and the second side of the QTG to generate electrical power; and

operating a downhole device using the generated electrical power.

18. The method of claim 17 wherein the borehole is a producing borehole, and wherein the downhole device is selected from (i) a flow control device, (ii) a packer, (iii) a choke, (iv) a perforating device, (v) an anchor, (vi) a completion device, and (vii) a production device.

19. The method of claim 17 wherein the QTG is part of a bottomhole assembly, the method further comprising conveying the downhole assembly into the borehole on a conveyance device selected from (i) a drilling tubular, and (ii) coiled tubing.

20. The method of claim 17 further comprising:

lowering a downhole assembly including the phase change material into the borehole;

wherein the first side of the QTG comprises a collector.

21. The method of claim 17 further comprising:

raising the downhole assembly including a phase change material;

wherein the first side of the QTG comprises an emitter.