MX2007001199A - Subterranean electro-thermal heating system and method - Google Patents

Abstract

A subterranean electro-thermal heating system including one or more heater cable sections extending through one or more heat target regions of a subterranean environment and one or more cold lead sections coupled to the heater cable section(s) and extending through one or more non-target regions of the subterranean environment. A cold lead section delivers electrical power to a heater cable section but generates less heat than the heater cable section. The heater cable section(s) and the cold lead section(s) are arranged to deliver thermal input to one or more localized areas in the subterranean environment.

Description

METHOD AND UNDERGROUND ELECTRO-THERMAL HEATING SYSTEM FIELD OF THE INVENTION The present invention relates to underground heating and, more particularly, to an underground electro-thermal heating method and system.

BACKGROUND OF THE INVENTION Heating systems can be used in underground environments for various purposes. In one application, underground heating systems can be used to facilitate oil production. The oil production index has decreased in many of the world's oil reserves due to difficulties in extracting the heavy oil that remains in the formation. Several problems can be faced that limit production when oil is extracted from a heavy oil field reservoir. For example, the high viscosity of the oil can cause low flow conditions. In petroleum that contains high percentage of paraffin, the paraffin can precipitate and form deposits in the walls of the tubes production, consequently the flow is choked off when the oil is pumped. In oil wells with high gas presence, gas expansion can occur when oil is brought to the surface, causing hydrate formation, which significantly lowers the oil temperature and consequently the flow.

Oil warming is a way to address these common problems that limit production and promote increased oil recovery (EOR). Both steam and electric heaters can be used as a source of heat to promote the EOR. One technique, referred to as heat tracing, includes the use of mechanical and / or electrical components placed in a pipe system to maintain the system at a predetermined temperature. Steam can be circulated through tubes, or electrical components can be placed in the tubes to heat the oil.

These techniques have some disadvantages. The steam injection system can be complicated by the inefficient use of energy, maintenance problems, environmental emergencies, and the inability to provide accurate and repeatable temperature control. Although electric heating is generally considered to be advantageous over heating with steam injection, electric heating systems typically causes unnecessary heating in regions where heating is not required to facilitate the flow of oil. Unnecessary heating is associated with inefficient use of power and can also cause environmental problems and undesirable melting of frozen areas in Arctic locations.

Therefore, an underground electro-thermal heating system is necessary that is able to reliably and efficiently deliver thermal input to areas located in an underground environment.

BRIEF DESCRIPTION OF THE FIGURES Advantages of the present invention may be apparent according to the following detailed description of illustrated embodiments thereof, which in the description should be considered in conjunction with the accompanying figures, wherein: Figures 1 to 4 are schematic diagrams of different embodiments of an underground electro-thermal heating system according to the present invention including various arrangements of heating cable sections and cold conduction sections.

Fig. 5 is a schematic diagram of one embodiment of an underground electro-thermal heating system according to the present invention used for downward heating in the cavity.

Figure 6 is a schematic cross-sectional view of a heating cable secured to a production pipe for exemplifying the downstream heating electro-thermal heating system in the cavity shown in Figure 5.

Figure 7 is a schematic diagram of a mode of a pressurized well that is fed through an assembly to connect a cold conduction section to a heating cable in an underground electro-thermal heating system for downward heating in the cavity in pressurized well.

Fig. 8 is a schematic perspective view of one embodiment of a downward heating cable in the externally installed cavity according to the present invention.

Figure 9 is a schematic view of the cross section of a heating cable shown in Figure 8.

Figure 10 is a schematic perspective view of another embodiment of a downstream heating cable in the externally installed cavity according to the present invention.

Figure 11 is a schematic view of the cross section of the heating cable shown in Figure 10.

Figure 12 is a schematic perspective view of one embodiment of a downstream heating cable in the internally installed cavity according to the present invention.

Figures 13 and 14 are schematic perspective views of the downward heating cable in the internally installed cavity shown in Figure 12 installed in a production tube.

Figure 15 is a schematic diagram of another embodiment of the electro-thermal heating system according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION In general, an underground electro-thermal heating system according to the invention can be used for deliver the thermal input to one or more areas located in an underground environment. Requests for underground electro-thermal heating system according to the invention includes, but is not limited to, thermal entry of oil deposits to increase oil recovery (EOR), soil improvement processes or groundwater compensation, generation In situ steam for purposes of EOR or recovery, and cracking of hydrocarbons in situ in localized areas to promote the reduction of the viscosity of petroleum or petroleum-laden deposits. Exemplifying modalities of an underground electro-thermal heating system are described in a context of oil production and EOR. This is understood, however, that the exemplified modalities are described for the explanation, and can not be limiting.

Figure 1 illustrates an exemplary embodiment 10 of an underground electro-thermal heating system in accordance with the present invention. The illustrated exemplification system 10 includes a power source 20 electrically coupled to a heater cable section 12 through a cold conduit cable section 16. The cold conduit cable section 16 is disposed in a non-target region. 18 of an underground environment 2, and the heater cable section 12 is disposed in a target region of heating 14 of the underground environment 2. The target heating region 14 can be a region in the underground environment 2 where it is desired to heat, for example to facilitate the flow of oil. The non-target region 18 can be a region in the underground environment 2 where heat is not desired and this is minimized, for example, to conserve energy or to avoid the application of significant heat to temperature sensitive areas such as frozen areas in an arctic underground environment.

The length, configuration and number of heater cable sections and cold conduction cable sections may vary depending on the application. In EOR applications, instances of cold conduction sections 16 may be around at least 700 meters in length and may extend up to about 1000 meters in length. Also, the heat generation in the cold conduction sections and the heating cable sections can be directly related to the energy consumption of these sections. In one embodiment, it is desirable that the power consumption in the cold conduction section (s) 16 be less than about 10% of the power consumption in the heater cable section (s) 12. In an EOR application, for example, the power consumption in the heater cable section 12 can be about 100 watts / ft and the power consumption in the cold conduit section 12 can be less than about 10 watts / ft. In In another embodiment, the cold conduction section or sections may be configured such that the voltage drops through the sections at or less than 15% of the total voltage that falls through all the sections of heating cable and cold conduction in the system.

Those of ordinary skill in the art will recognize that the power consumption and voltage drop in the cold conduction sections may vary depending on the electrical characteristics of the particular system. Table 1 below illustrates the power consumption and voltage drop of the line for cold conduction sections and various conductor sizes and lengths of 700, 800, 900, and 1000 meters in a system where the power source is a single phase 480 volt source and in a system where the power source is a three phase 480 volt source. Table 2 below illustrates the power consumption and line voltage drop for cold conduction sections of various conductor sizes and lengths of 700, 800, 900, and 1000 meters in a system where the power source is a single-phase 600V source and in a system where the power source is a three-phase 600V source. For the exemplified configurations described in Tables 1 and 2, the cold conduction conductor has a size that does not exceed a 15% voltage drop or 10 wa 11 s / ft of the well, and the conductor temperature was set at an average of 75 ° C.

TABLE 1 Single Phase 480 Volts Three Phase 480 Volts 15 KW Current / Driver = > 31 .3 Amperes 18.0 Amperes Volts W / Foot. Volts W / Foot.

Driving length Driver Driver's drop Falling Meters Feet Size% Source Size% Source 700 2297 6 14 1 .0 8 12 0.8 800 2625 4 1 1 0.6 8 14 0.8 900 2953 4 12 0.6 8 15 0.8 1000 3281 4 14 0.6 6 1 1 0.5 KW Current / Driver = 52.1 Amps 30.1 Amps Volts W / Foot. Volts W / Foot.

Conductor Length Conductor Falling Drop Meters Feet Size% Source Size% Source 700 2297 3 12 1 .3 6 13 1 .3 800 2625 3 14 1.3 6 14 1.3 900 2953 2 13 1 .1 4 10 0.9 1000 3281 2 14 1 .1 4 12 0.9 50 KW Current / Driver = > 104.2 Amps 60.1 Amps Volts W / Foot. Volts W / Foot.

Driving length Driver Driver's drop Falling Meters Feet Size% Source Size Font Well 700 2297 1/0 12 2.7 3 12 2.7 800 2625 1/0 14 2.7 3 14 2.7 900 2953 2/0 13 2.1 2 13 2.1 1000 3281 2/0 14 2.1 2 14 2.1 TABLE 2 Single Phase 600 Volts Three Phase 600 Volts 15 KW Current / Driver = > 25.0 Amps 14.4 Amps Volts W / Foot. Volts W / Foot.

Driving length Driver Driver's drop Falling Meters Feet Size% Source Size% Source 700 2297 8 15 1 10 12 0.8 800 2625 6 11 0.6 10 14 0.8 900 2953 6 12 0.6 8 10 0.5 1000 3281 6 14 0.6 8 11 0.5 KW Current / Driver = > 41.7 Amperes 24.1 Amps Volts W / Foot. Volts W / Foot.

Driving length Driver Driver's drop Falling Meters Feet Size% Source Size% Source 700 2297 4 '10 1.1 8 13 1.4 800 2625 4 12 1.1 8 15 1.4 900 2953 4 13 1.1 6 10 0.9 1000 3281 4 15 1.1 6 11 0.9 50 KW Current / Driver = > 83.3 Amperes 48.1 Amperes Volts W / Foot. Volts W / Foot.

Driving length Driver Driver's drop Falling Meters Feet Size% Source Size% Source 700 2297 2 13 2.7 4 10 2.2 800 2625 2 14 2.7 4 12 2.2 900 2953 1 13 2.2 4 13 2.2 1000 3281 1 14 2.2 4 15 2.2 One or more cold driving sections and ropes in accordance with the present invention may be provided in a variety of configurations depending on the requirements of the system. Figure 12, for example, illustrates another illustrative embodiment 10a of an electrothermal heating system in accordance with the invention. In that illustrative embodiment, a heater cable section 12 and a cold conduit section 16 have a generally vertical orientation in the underground environment 2. The cold conduit section extends along a non-target area of an underground environment. for electrically connecting the heating cable section 12 in the target region 14 to a power source 20. Those with ordinary skills in this art will recognize that a system consistent with the invention is not limited to a particular orientation, but can be implemented in horizontal, vertical orientation, or in other orientations or combinations of orientations within the underground environment 12. The orientation of a specific system may depend on the requirements of the system and / or the orientation of the areas be heated A system according to the invention can Deploy in a segmented configuration, as shown. For example, in Figures 3 and 4. Figure 3 illustrates an underground electro-thermal heating system 10b with an arrangement of multiple heater cable sections 12 and cold conduction sections 16. The heater cable sections 12 and the cold conduction sections are configured, interconnected and positioned based on a predefined pattern of target heating areas 14 and non-target areas 18 in the underground environment 2. Thus, heater cable sections 12 and cold conduction sections 16 can be located strategically to focus the electro-thermal energy to multiple desired areas in the underground environment 2, while regulating the heat input and avoiding unnecessary heating. Figure 4 shows another illustrative embodiment 10c of a system according to the invention in which the heater cable sections 12 and the cold conduit sections have various lengths depending on the size of the corresponding heating target areas 14 and non-target regions 18. Although the illustrative embodiments show specific patterns, configurations, and orientations, the heater cable sections and the cold conduit sections can be accommodated in other patterns, configurations, and orientations.

The heater cable sections 12 can include any type of heater cable that converts electrical energy into heat. Such heating cables are generally known to those skilled in the art and may include, but are not limited to, standard three phase constant voltage cables, insulated mineral cables (MI), and skin effect tracer (STS) systems.

An example of MI cable includes three (3) equally spaced nickel chrome power conductors that are connected to a voltage source to a power source and electrically connected to a final termination, creating a constant current in the heating cable. The MI cable may also include a liner made of a corrosion resistant alloy such as the type available under the name "Inconel".

In an example of an STS heating system, heat is generated on an internal surface of a hot ferromagnetic pipe that is thermally coupled to the structure to be heated (eg, to a petroleum pipe). A temperature resistant, electrically insulated conductor is installed inside the heating tube and connected to the tube at the end. The tube and conductor are connected to an AC voltage source in a series connection. The return section of the current circuit is pulled to the inner surface of the heat pipe both by the skin effect and by the proximity effect between the heat pipe and the conductor.

In one embodiment, the cold conduction section 16 may be a cable configured to electrically connect to the heating cable section 12 and to supply electrical power to the heating cable 12 while generating less heat than the heating cable section 16. design of the section of Cold conduction 16 may depend on the type of heating cable and the manner in which the heat is generated using the heating cable. When the heater cable section 12 includes a conductor or interconnecting cable and uses resistors to generate heat, for example, the conduit section of triol 6 can be configured with an interconnecting conductor or cable with a lower resistance (eg a in cross section larger). The lower resistance allows the cold conduction section 16 to conduct electricity to the heating section 12 while minimizing and preventing the generation of heat. When the heating section 12 is an STS heating system, the cold conduction section 16 can be configured with a material different from that of the heating tube and with a different joint between the tube and the conductor to minimize or prevent the generation of heat .

In an OER application, an electro-thermal heating system in accordance with the present invention can be used to provide both a downward heating in the cavity or from the bottom. The system can be secured in the structure containing the oil, such as the production pipe or an oil tank, to heat the oil in the structure. In these applications, at least one cooling section 16 can be of an appropriate length to pass through the soil to a location where the oil is to be heated, for example, the desired location in the production pipe or to the upper surface of the oil tank. A system according to the invention can also, or alternatively, be configured to indirectly heat the oil within a structure. For example, the system can be configured to heat injected miscible gases or liquids which are used to heat the oil to promote EOR.

One embodiment of a descending underground electrothermal heating system according to the present invention is shown in Figures 5 to 7. The descending underground electrothermal heating system 30 includes a heater cable section 32 secured to a production pipe 34 and a cold conduction section 36 connecting the heater cable section 32a to a power source equipment 38, such as a power panel or a transformer. A power connector 40 electrically connects the cold conduction section 36, the heating cable section 32a to a final termination 42 and terminates in the heating cable section 36.

The cold conduction section 36 extends through the lid 35 and lowers a separate production tube 34a to a location in the production tube 34 where heating is desired. The length of the cold conduction section 36 extending down into the production pipe 34 can depending on where heating is desired in the production pipe 34 to facilitate the flow of oil, and can be determined by one skilled in the art. The length of the cold conduction section 36a along the production pipe 34 may also depend on the depth of any non-target area (eg, an icy zone) through which the cold conduction section extends. In an example. The cold conduction section 36 extends about 700 meters and the section of the heating cable 32 extends down to the oil source in a range between 700 and 1500 meters. Although a section of heating cable 32 and a cold conduction section 36 are shown in this illustrative embodiment, other combinations of multiple heating cable sections 32 and cold conduction sections 36 are contemplated, for example, in the form of a configuration segmented along the production pipe 34.

An example of the heating cable section 32 is a three phase constant voltage shielded and fluoro polymer lined voltage cable, and an example of the cold conducting section 36 is a 10 mm shielded 3 wire cable. squares. The power conductor 40 may include a steel fiber shell with fluoro propylene insulations to provide axial mechanical protection as for a good electrical connection. The power connector 40 can also be mechanically and thermally protected sealing it in a hollow cylindrical steel assembly using a series of "eyelets" and "encapsulated" with a silicone-based compound.

The final termination 42 may include molten fluoro propylene insulation to provide axial mechanical protection as an electrical termination Y of the conductors in the heater cable section 32.

As shown in FIGS. 6, the heater cable section 32 can be secured to the production tube using a conductor 44, such as a rigid steel conductor, and fastening bands 46 spaced along the conductor 44 (for example every 4 feet). The conductor 44 protects the section of the heating cable 32 from abrasion and crushing and ensures the consistent transfer of heat from the heating cable 32 to the fluid in the production pipe 34. An example of the conductor 44 is a 16 gauge steel conductor and an example of fastening bands 46 are those of ½ inch wide stainless steel.

In use, the heater cable section 32 can be unwound and fastened to the production tube 34 as the tube 34 is lowered towards the source. Before lowering the last section of the production tube 34 towards the source, the section of the heating cable 32 can be cut and joined to the section of cold conduction 36. The cold conduction section 36 can be fed through the source cover and connected to the power source equipment 38. For non-pressurized source covers, the cold conduction section 36 can be assembled directly to the section of heater cable 32 using the power connector 40.

For pressurized source covers, a power supply assembly with mandrel 50, shown in Figure 7, can be used to penetrate the source cover. The illustrative example of mandrel power supply assembly 50 includes a mandrel 52 that passes through the pressurized source head. A surface plug connector 54 is electrically coupled to a power source and connected to an upper connector 51 of the mandrel 52. A lower connector 56 is coupled to one of the cable systems 53 (i.e. to a cable section). heater or a cold conduction section) and connect to the lower connector 55 of the mandrel 52.

Again, those with ordinary skills in this area will recognize a variety of cable arrangements that can be used as heater cable in a system consistent with the present invention. An illustrative embodiment of an externally installed downstream heating cable 32 for use in non-pressurized sources is shown in Figures 8 to 9. This section of heating cable 32 provides a three-phase power that produces 11 to 14 watts / ft and can be installed on the outside of the production pipe in a conductor, as described above.

Figures 10 to 11 illustrate another embodiment 32a of an externally installed downstream heater cable section for use in pressurized sources in a manner consistent with the present invention. The exemplified cable section 32a provided with three-phase power produces 14 to 18 watts / ft. and can be installed on the outside of the production pipe within a channel and using the feed pass chuck, as described above.

Another embodiment of a descending underground electro-thermal heating system in the cavity 60 includes a heater cable section 62 downwardly in the internally installed cavity and a cold conduit section 66 for use in a pressurized or non-pressurized well, as shown. in Figures 12 to 14. The exemplification of heater cable sections 62 installed internally supplies three-phase power and produces from 8 to 10 watts / ft. Internally installed heater cable sections 62 may have a small diameter (e.g., about 1/4 inch) and may provide a continuous cable without a splice in a length of approximately 700 meters. Sections of heater cables 62 installed internally may also have a cover corrosion resistant constructed, for example, from "I n c o I o y" ® 825. The heater cable sections 62 installed internally can simply be installed relatively without influencing the production line.

Another embodiment of an underground electro-thermal heating system 70 is shown in Figure 15. In this embodiment, a heater cable section 72 STS has a cold conduit section 76 coupled thereto, secured to a reservoir or tube 74 that runs usually horizontally in the underground environment. Although a heater cable section 72 STS and a cold conduit section 76 are shown, other combinations of multiple heater cable sections 72 STS and cold conduction sections 76 are contemplated, for example, to form a segmented configuration along the reservoir or tube 74.

In one embodiment, the components of the underground electro-thermal heating system (e.g. heating cables, cold conductors, power connectors, and extreme terminations) may be provided separately to be assembled in the field in accordance with the designated heating pattern and regions not objective in the underground environment. For example, one or more sections of heating cables can be cut according to the number and dimensions of the designated heating target regions and one or more sections of cold conductors can be cut according to the number and dimensions of the non-target regions. Heating cables and cold conductors can then be interconnected and positioned properly in the underground environment.

Therefore, an underground electro-thermal heating system according to the invention includes one or more cold conduction sections allowed by the strategic placement of heat inputs without necessarily heating certain underground regions. The use of one or more cold conduction sections can reduce the operating energy used and can minimize environmental problems such as heating through frozen zones. The underground electro-thermal heating system also allows segmented heat applications.

Although the principles of the invention have been described herein, it can be understood that this description is made solely to allow for exemplifications and not as limitations as to the scope of the invention. Other embodiments are contemplated within the scope of the present invention, in addition to the embodiments exemplified, shown and described herein. Modifications and substitutions by someone with ordinary knowledge in the art is considered within the scope of the present invention, which is not limited except by the following claims.

Claims (47)

R E I V I N D I C A C I O N S

1. - An underground electro-thermal heating system comprising: At least one section of heating cable configured to generate a thermal output of the heating cable to extend it in at least one target heating region of an underground environment; and At least one cold conduction section electrically connected to said heating cable section and configured to extend through at least one non-target region of said underground environment to deliver electrical energy to said heating cable section, said cold conduction section generating a cold conduction thermal output smaller than said thermal output of the heating cable.

2. - The system according to claim 1, wherein said at least one cold conduction section has a length greater than or equal to 700 meters.

3. - The system according to claim 1, wherein said at least one cold conduction section is configured to consume less than or equal to 10% of the energy consumed by said at least one section of heating cable.

4. - The system according to claim 1, wherein said at least one cold conduction section is configured such that a voltage drop across said cold conduction section is less than or equal to 15% of a total voltage drop through said at least one cold conduction section and said at least one section of heating cable.

5. - The system according to claim 1, wherein said heating cable section is disposed attached to a fluid containment structure at least partially disposed within said designated heating region of said underground environment for heating the fluid in said structure .

6. - The system according to claim 5, wherein said fluid containment structure comprises a reservoir in said underground environment.

7. - The system according to claim 5, wherein said fluid comprises oil.

8. - The system according to claim 5, wherein said fluid containment structure comprises a petroleum production tube and said fluid comprises oil.

9. - The system according to claim 8, wherein said Heating cable section is disposed within said oil production pipe.

10. - The system according to claim 8, wherein said heating cable section is located outside said oil production tube.

11. - The system according to claim 1, said system comprising a plurality of sections of heating cables and said cold conduction sections interconnected alternately to form a segmented electro-thermal heating system.

12. - The system according to claim 1, said system further comprising a source of electric power connected to an end of at least one of said cold conduction sections.

13. - The system according to claim 1, said system further comprising a power connector connected said heating cable sections with said cold conduction sections.

14. - The system according to claim 1, said system further comprising at least one extreme termination connected to one end of at least one of said sections of heating cables.

15. - The system according to claim 1, wherein said heating cable section comprises a section of isolated mineral cable.

16. - The system according to claim 1, wherein said section of heating cable comprises a heat conducting cable that provides a first resistance, and wherein said cold conduction section comprises a cold conducting conductor wire electrically connected to said conductive cable of heat, said cold conducting conductor cable provides a second resistance lower than said first resistance.

17. - The system according to claim 1, wherein said heating cable section comprises a tracing system with "skin effect".

18. - The system according to claim 1, wherein said section of cold conduction cable and said section of heating cable extend through a cover of the source.

19. - The system according to claim 1, comprising: A surface plug connector; A feeder mandrel extended through a lid of the pressurized source and having a first end coupled to said surface plug connector; and A lower plug connector having a first end coupled to a second end of said feeder mandrel and having a second end coupled to a first end of said sections of cold conduction cable.

20. - An underground electro-thermal heating system comprising: At least one section of heating cable arranged attached to a fluid containment structure in an underground environment to generate a thermal output of the heating cable to a fluid in said fluid containment structure; and At least one cold conduction section electrically connected to said heating cable section and extended through at least one non-target region of said underground environment to deliver electrical energy to said section of heating cable, said cold conduction section generating an output thermal conduction cold less than said thermal output of the heating cable and is configured to consume less than or equal to 10% of the energy consumption of said at least one section of heating cable.

21. - The system according to claim 20, wherein said at least one cold driving section has a length greater than or equal to 700 meters.

22. - The system according to claim 20, wherein said at least one cold conduction section is configured such that a voltage drop across said cold conduction section is less than or equal to 15% of a total voltage drop through said at least one cold conduction section and said at least one heating cable section.

23. - The system according to claim 20, wherein said fluid containment structure comprises a reservoir in said underground environment.

24. - The system according to claim 20, wherein said fluid comprises oil.

25. - The system according to claim 20, wherein said fluid containment structure comprises a petroleum production tube and said fluid comprises oil.

26. - The system according to claim 25, wherein said heating cable section is at least partially disposed within said oil production pipe.

27. - The system according to claim 25, wherein said heating cable section is located outside said oil production pipe.

28. - The system according to claim 20, said system comprising a plurality of said sections of heating cables and said cold conduction sections interconnected alternately to form a segmented electro-thermal heating system.

29. - The system according to the rei indication 20, said system further comprising a source of electric power connected to one end of at least one of said cold conduction sections.

30. - The system according to claim 20, said system further comprising an energy connector connected to said heating cable section with said cold conduction section.

31. - The system according to claim 20, said system further comprising at least one end termination connected to one end of at least one of said heater cable sections.

32. - The system according to claim 20, wherein said heating cable section comprises an insulated mineral cable section.

33. - The system according to claim 20, wherein said heating cable section comprises a heat conducting cable that provides a first resistance, and wherein said cold conduction section comprises a cold conductive cable electrically connected to said conductive cable of heat, said cold conducting conductor cable provides a second resistance lower than said first resistance.

34. - The system according to claim 20, wherein said heating cable section comprises a "skin-effect" tracing system.

35. - The system according to claim 20, wherein said cold conduction cable section and said heating cable section extend through a source cover.

36. - The system according to claim 20, further comprising: A surface plug connector; A feeder mandrel extended through a lid of the pressurized source and having a first end coupled to said surface plug connector; Y A lower plug connector having a first end coupled to a second end of said feeder mandrel and having a second end coupled to a first end of said cold conductor cable sections.

37. - A method of configuring an underground heating system to deliver a thermal input to areas located in an underground environment, said method comprising: Defining a pattern of at least one target region for heating and at least one non-target region within said environment Underground; Connecting at least one section of cold conduction cable with at least one section of heating cable; and positioning said cold conduction section and said heating cable section in said underground environment such that said heating cable section extends into and associated with said target regions for heating to provide a thermal output of the heating cable to said related heating target region. and said cold conduction section passing through said related non-target region to provide a related cold conduction thermal output lower than said thermal output of the heating cable.

38. - The method of claim 37, wherein said at least one cold conduction section has a length greater than or equal to 700 meters.

39. - The method of claim 37, wherein said at least one cold conduction section is configured to consume less than or equal to 10% of the energy consumed by said at least one section of heating cable.

40. - The method of claim 37, wherein said at least one cold conduction section is configured such that a voltage drop across said cold conduction section is less than or equal to 15% of a total voltage drop across said at least one cold conduction section and said at least one section of heating cable.

41. The method of claim 37, wherein said heating cable section is disposed attached to a fluid containment structure at least partially disposed within said designated heating region of said underground environment for heating the fluid in said structure.

42. - The method of claim 41, wherein said fluid containment structure comprises a reservoir in said underground environment.

43. - The method of claim 41, wherein said fluid includes oil

44. - The method of claim 41, wherein said fluid containment structure comprises a petroleum production tube and said fluid comprises petroleum.

45. - The method of claim 44, wherein said heating cable section is at least partially disposed within said oil production pipe.

46. - The method of the re-indication 44, wherein said section of heating cable is located outside said oil production pipe.

47. The method of claim 37, wherein said at least one section of cold conduction cable interconnected with at least one section of heating cable comprises alternately interconnected a plurality of said sections of cold conduction cable with a plurality of sections of heating cables. to form a segmented electro-thermal heating system. SUMMARY An underground electro-thermal heating system includes one or more sections of heating cables extended through one or more target regions for heating an underground environment and one or more cold conduction sections coupled to the section (s) of heater cable and extended through one or more non-target regions of an underground environment. A cold driving section delivers electrical energy to a section of heating cable but generally smaller than the section of heating cable. The heater cable section or sections and the cold conduit section or sections are arranged to provide a thermal input to one or more areas located in the subsurface environment.