RU2585776C2 - Methods of connecting insulated conductors - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: group of inventions relates to a method of connecting insulated conductors in treating subsurface formation. Method of connecting two insulated conductor ends includes connection of end section of core of first insulated conductor with end section of core of second insulated conductor. At least part of end sections of cores is at least partially bare. Electrically insulating material is placed on top of bare sections of cores. Sleeve is placed on top of end sections of two connected insulated conductors. Said sleeve has one or more raised sections. End sections include bare areas of cores. Sleeve is connected with cladding of conductors. Mechanical compression of raised sections of sleeve is carried out until raised sleeve sections have diameter, essentially similar to diameter of remaining part of sleeve. During compression of raised sections of sleeve, electrically insulating material inside said sleeve is pressed.

EFFECT: high efficiency of connection and improved insulating properties.

13 cl, 54 dwg

Description

FIELD OF THE INVENTION

The present invention relates to systems for insulated conductors used in heating elements. In particular, the invention relates to fittings for splicing together insulated conductive cables.

State of the art

Hydrocarbons mined from underground formations are often used as sources of energy, raw materials for industry and the manufacture of consumer goods. Concerns about the depletion of existing hydrocarbon reserves and fears about a decrease in the overall quality of produced hydrocarbons have led to the development of processes aimed at improving the efficiency of extraction, processing and / or use of hydrocarbon resources. In-situ processes can be used to recover hydrocarbon materials from underground formations that were previously unavailable and / or too expensive to recover using existing methods. To more easily recover hydrocarbon material from the subterranean formation and / or increase the cost of the hydrocarbon material, a change in the chemical and / or physical properties of the hydrocarbon material in the subterranean formation may be required. Chemical and physical changes may include in situ reactions that produce recoverable fluids, changes in composition, changes in solubility, changes in density, phase transitions and / or changes in the viscosity of the hydrocarbon material in the formation.

Heaters can be placed in wellbores to heat the formation during on-site processes. There are many different types of heaters that can be used to heat the formation. Examples of on-site processes using downhole heaters are described in US Pat. No. 2,634,961 to Lungstram; US 2,732,195 to Lungstram; US 2,780,450 in the name of Lungstram; US 2,789,805 to Lungstram; US 2,923,535 to Lungstram; US 4,886,118 to Van Mürs et al; and US 6,688,387 addressed to Wellington et al.

Mineral insulated cables (MI) (insulated conductors) designed for underground use, for example, in certain applications for heating hydrocarbon-containing formations, have an increased length, can have an increased external diameter and can be used at higher voltages and temperatures compared to with generally accepted values for mineral insulated cables. The manufacture and / or installation of long insulated conductors presents many potential problems.

For example, electrical and / or mechanical problems could potentially arise due to destruction over time of the electrical insulation used in the insulated conductor. Potentially, problems can arise with electrical insulators, which have to be solved when installing a heater with an insulated conductor. When installing a heater with an insulated conductor, problems such as bloating of the core or other mechanical malfunctions can occur. Such problems can create power problems during use of the heater and potentially make the heater unsuitable for the task assigned to it.

In addition, in underground applications, it may be necessary to connect several mineral insulated cables to produce mineral insulated cables of sufficient length extending to such a depth and distance that it is possible to efficiently heat the underground formation and connect areas with different functionality, for example, connect input cables with heater sections. Such long heaters also require increased voltage to supply enough energy to the farthest ends of the heaters.

Traditional spliced mineral insulated cable designs are usually not suitable for voltages above 1000 D, above 1500 D or above 2000 V and cannot function for a long time without failures at elevated temperatures, for example, above 650 ° C, above 700 ° C or above 800 ° C. For such applications with high voltage and high temperature, it is usually necessary to compress the mineral insulating material in the splicing so that it is located as close as possible to the level of compression or is above the level of compression directly in the insulated conductor (cable with mineral insulation).

The relatively large outer diameter and long mineral-insulated cable lengths for some applications require that the cable splices be carried out with the cables horizontal. Mineral-insulated cables that are laid horizontally for other applications are also spliced. Such a technology usually involves making a small hole through which mineral insulation (for example, powdered magnesium oxide) is filled into a splice and slightly compressed by vibration or ramming. Such methods do not provide sufficient compression of the mineral insulation, or do not provide any compression of the mineral insulation and are not suitable for splicing when used under high stress conditions required for such underground applications.

Therefore, there is a need for splices for insulated conductors, which, despite their simplicity, can function at high voltages and temperatures in underground conditions for a long time, without breakage. In addition, to prevent breakage of the splice under the weight load and temperatures to which cables can be exposed underground, the splice must have high bending strength and tensile strength. You can also use technologies and methods to reduce the intensity of the electric field in the splices in such a way as to reduce the loss currents in the splices and to increase the interval between the operating voltage and electrical breakdown. Reducing the intensity of the electric field allows you to increase the voltage and the operating temperature range for splices.

In addition, problems may arise associated with an increase in the tension of insulated conductors during installation and / or installation of insulated conductors underground. For example, winding or unwinding insulated conductors on coils before transporting and installing insulated conductors can lead to mechanical stress on electrical conductors and / or other components of insulated conductors. Therefore, more reliable systems and methods are needed to reduce or prevent potential problems encountered during the manufacture, installation and / or installation of insulated conductors.

Disclosure of invention

The embodiments discussed herein generally relate to systems, methods, and heaters for treating subterranean formations. The embodiments discussed herein also apply to heaters that use innovative components. Similar heaters can be obtained using the systems and methods discussed herein.

In some embodiments, the invention provides one or more systems, methods, and / or heaters. In certain embodiments, systems, methods, and / or heaters are used to treat subterranean formations.

In some embodiments, a method for connecting the ends of two insulated conductors includes: connecting the end portion of the core of the first insulated conductor to the end portion of the core of the second insulated conductor, wherein at least a portion of the end portions of the cores are at least partially exposed; placement of electrical insulation material over exposed core sections; placing the sleeve over the end sections of two connected insulated conductors, the sleeve having one or more raised sections, the end sections including exposed core sections; connection of the sleeve with the shells of insulated conductors; and mechanical compression of the raised portions of the sleeve until the diameter of the raised portions of the sleeve essentially becomes the same as the rest of the sleeve, while compressing the raised portions of the sleeve, the insulating material is compressed inside the sleeve.

In some embodiments, a method for connecting the ends of two insulated conductors includes: connecting the end portion of the core of the first insulated conductor to the end portion of the core of the second insulated conductor, wherein at least a portion of the end portions of the cores are at least partially exposed; placement of electrical insulation material over exposed core sections; placing the inner sleeve over the end sections of two connected insulated conductors, the end sections including exposed core sections; placing the outer sleeve over the inner sleeve, while there is free space between the inner sleeve and the outer sleeve, and there is an opening in the outer sleeve; the connection of the inner sleeve and the outer sleeve with the shells of insulated conductors; and supplying the fluid under pressure to the free volume between the inner sleeve and the outer sleeve to press the inner sleeve into the insulating material and compressing the insulating material.

In some embodiments, a fitting for connecting the ends of insulated conductors includes: an inner sleeve placed during use over the end portions of the first insulated conductor and the second insulated conductor, the inner sleeve being placed over at least partially exposed end portions of the core of the insulated conductors, and an electrical insulator the material is placed during use on top of the exposed end portions of the cores inside the sleeve; moreover, in the outer sleeve there is a hole located above the inner sleeve, while there is free space between the inner sleeve and the outer sleeve; moreover, the inner sleeve and the outer sleeve during use are connected to the shells of insulated conductors; wherein the inner sleeve is compressed during use by the fluid under pressure supplied to the free volume between the inner sleeve and the outer sleeve, and when the inner sleeve is compressed, the insulating material is compressed in the inner sleeve.

In some embodiments, the method for connecting the ends of the cores of three insulated conductors includes: placing an end termination over sections of three insulated conductors, and in the end termination there are three separate holes extending longitudinally through the end termination, each of the insulated conductors passing through one of the openings such so that the end portions of the insulated conductors protrude on one side of the termination; exposure of the cores at the end sections of insulated conductors protruding from the end terminations by removing the sheath and electrical insulation from the end sections; connection of the ends of the shells of insulated conductors with termination; the connection of the cylinder with the side of the termination, from which the end sections of the insulated conductors protrude; filling the cylinder with electrical insulating material so that at least a portion of the cores remains exposed; connection of an electric bus with bare core sections; filling the cylinder with an insulating material such that the cores are substantially packed in an insulating material; and connecting the end cap to the cylinder to seal the inside of the cylinder.

In some embodiments, a fitting for connecting the ends of the cores of three insulated conductors includes: an end termination placed over the end portions of three insulated conductors, in which there are three separate holes in the end termination extending longitudinally through the end termination, each of the insulated conductors passes through one from the holes in such a way that the end sections of the insulated conductors protrude on one side of the end seal, the bare cores of the end sections of -insulated conductors protrude from the end fitting; a cylinder connected to a termination side from which end portions of insulated conductors protrude; an electric bus connected to the exposed sections of the cores; an electrical insulating material filling the cylinder so that the cores are substantially packed in electrical insulating material; and an end cap connected to the cylinder to seal the inside of the cylinder.

According to some embodiments, a method for transferring a three-phase heater with an earth-closed portion to a single-phase mode using a three-phase power supply includes: installing a resistor between the neutral wire of the power source and the ground-closed portion of the three-phase heater so that the passage passes through the earth-closed portion the minimum current, or the current did not pass at all, while the resistor is connected in series with the area closed to the ground; supplying power to the other two sections of the heater from the power source so that the two sections function as a single-phase heater, with the current passing into the reservoir in one section and returning to the other section in which the two sections are connected underground using a fitting in which there is: an end termination placed over the end sections of three insulated conductors, in which there are three separate holes in the end termination extending longitudinally through the end termination, each of -insulated conductor passes through one of the openings so that the end portions of the insulated conductors protrude from one side of the end fitting, the end portions of the cores exposed insulated conductors project from an end seal; a cylinder connected to a termination side from which end portions of insulated conductors protrude; an electric bus connected to the exposed sections of the cores; an electrical insulating material filling the cylinder so that the cores are substantially packed in electrical insulating material; and an end cap connected to the cylinder to seal the inside of the cylinder.

In some embodiments, a fitting for connecting one end of the first insulated conductor to one of the ends of the second insulated conductor includes: a sleeve configured to be placed on top of the end of the first insulated conductor and the end of the second insulated conductor; and a coupling sleeve for connecting the cores located inside the sleeve, a coupling sleeve for connecting the cores is made to be worn around one of the ends of the core of the first insulated conductor and one of the ends of the core of the second insulated conductor, while the cores of the insulated conductors are arranged to move together in the coupling for connection cores after the ends of insulated conductors are placed in a sleeve and there is a predetermined gap between the ends of the cores; moreover, the inner volume of the sleeve is made with the possibility of at least partially filling it with an insulating material, and the insulating material is arranged to compress it with the end portion of the insulator of the first insulated conductor and the end portion of the insulator of the second insulated conductor after connecting the fitting to insulated conductors.

In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any other embodiments.

In additional embodiments, the subterranean formation is processed using any of the methods, systems, power supplies, or heaters discussed here.

In further embodiments, additional features may be added to the particular embodiments discussed herein.

Brief Description of the Drawings

The features and advantages of the methods and apparatus of the present invention will become more apparent with reference to the following detailed description of the currently preferred, but nonetheless illustrative embodiments of the present invention in conjunction with the accompanying drawings.

Figure 1 shows a schematic view of one embodiment of a portion of a heat treatment system in situ for treating a hydrocarbon containing formation.

Figure 2 shows one embodiment of a heat source of an insulated conductor.

Figure 3 shows one embodiment of a heat source of an insulated conductor.

Figure 4 shows one embodiment of a heat source of an insulated conductor.

Figure 5 shows a side view in cross section of one embodiment of a fitting for connecting insulated conductors.

Figure 6 shows one embodiment of a cutting tool.

7 shows a side view in cross section of another embodiment of a fitting for connecting insulated conductors.

On figa shows a side view in cross section of one embodiment of a threaded fitting for connecting three insulated conductors.

On figv shows a side view in cross section of one embodiment of a welded fitting for connecting three insulated conductors.

Figure 9 shows one embodiment of a torque tool.

Figure 10 shows one embodiment of a clamping device that can be used to mechanically compress a fitting when connecting insulated conductors.

11 shows an exploded view of one embodiment of a hydraulic press.

On Fig shows a picture of one of the embodiments of the assembled hydraulic press.

13 shows one embodiment of a fitting and insulated conductors secured in clamping devices before pressing the fitting and insulated conductors.

On Fig shows a side view of another, another embodiment of a fitting for connecting insulated conductors.

On Fig shows a side view of one of the embodiments of the fitting with the hole closed by the insert.

On Fig shows one of the embodiments of the fitting with devices to reduce the electric field located between the shells of insulated conductors and bushings, as well as at the ends of insulated conductors.

On Fig shows one of the embodiments of the device to reduce the electric field strength.

On Fig shows a view in section of a fitting at a time when insulated conductors are placed in the fitting.

On Fig shows a view in section of a fitting after connecting insulated conductors inside the fitting.

On Fig shows a view in cross section of another, another embodiment of the fitting at the moment when the insulated conductors are placed in the fitting.

On Fig shows a cross-sectional view of another, another embodiment of the fitting after connecting the insulated conductors inside the fitting.

On Fig depicts one of the embodiments of the blocks of insulating material located around the cores of the connected insulated conductors.

On Fig shows one of the embodiments of four blocks of insulating material located around the cores of the connected insulated conductors.

24 shows one embodiment of an inner sleeve placed over connected insulated conductors.

25 shows one embodiment of an external sleeve mounted around an internal sleeve and connected insulated conductors.

FIG. 26 shows one embodiment of the tapered end of an insulated conductor after compression.

On Fig depicted one of the embodiments of the first half of the compression device used to compress the insulating material when connecting insulated conductors.

On Fig shows one of the embodiments of the device connected around insulated conductors.

On Fig shows a side view of an insulated conductor inside the device when the first plunger is in position above the insulated conductor with a bare core.

On Fig shows a side view of an insulated conductor inside the device when the second plunger is in position above the insulated conductor with a bare core.

On figa-D shows other embodiments of the second plunger.

On Fig depicted one of the embodiments in which the second half of the device is removed, and the first half is left to compress the insulating material around the coupling between the insulated conductors.

FIG. 33 shows one embodiment of an electrical insulating material located around an insulated conductor coupling.

On Fig shows one of the embodiments of the sleeve, placed around the insulating material.

On Fig shows one of the embodiments of a hydraulic press, which can be used to apply force to the plunger for hydraulic pressing of the insulating material inside the device.

On Fig depicted one of the embodiments of the sleeve used for circumferential mechanical compression.

On Fig shows one of the embodiments of the sleeve on insulated conductors after the sleeve and ribs were pressed around the circumference.

On Fig depicts one of the embodiments of the amplification bushings on connected insulated conductors.

On Fig shows an exploded view of another embodiment of a fitting used to connect three insulated conductors.

Figures 40-47 show one embodiment of a method for installing a fitting at the ends of insulated conductors.

On Fig depicted one of the embodiments of the compression tool, which can be used to compress the insulating material.

On Fig depicts one of the embodiments of another compression tool that can be used to compress the insulating material.

On Fig depicts one of the embodiments of the compression tool, which can be used for the final compression of the insulating material.

Although the invention is subject to various modifications and alternative forms, the drawings, by way of example, show specific embodiments thereof, which will be discussed in more detail below. Drawings may not be given to scale. It should be understood that the drawings and the detailed description of the invention are not intended to limit the invention to the particular form disclosed, on the contrary, the invention encompasses any modifications, analogs, and alternatives that are not beyond the scope and essence of the present invention, as defined in the claims.

The implementation of the invention

The following description generally relates to systems and methods for treating hydrocarbons in formations. Processing such formations can be carried out to extract hydrocarbon products, hydrogen, as well as other products.

The term "alternating current" refers to a time-varying current that reverses its direction, essentially sinusoidally. Alternating current creates a surface effect in the ferromagnetic conductor when current flows.

The term “connected” means either a direct connection or an indirect connection (for example, one or more intermediate compounds) between one or more objects or components. The phrase “directly connected” means a direct connection between objects or components so that the objects or components are connected directly to each other so that the objects or components operate in a “point of use” mode.

The term “formation” includes one or more hydrocarbon-containing layers, one or more non-hydrocarbon layers, overlapping and / or underlying rock. The term "hydrocarbon layers" refers to reservoir layers that contain hydrocarbons. The hydrocarbon layers may contain non-hydrocarbon material and hydrocarbon material. “Overlapping” and / or “underlying” rocks include one or more different types of impermeable materials. For example, the overburden and / or bedrock may include rock, shale, mudstone, or wet / impermeable carbonate. In certain embodiments of the on-site heat treatment processes, the overburden and / or underlying rock may include a hydrocarbon-containing layer or hydrocarbon-containing layers that are relatively impermeable and are not exposed to temperature during the on-site heat treatment, which results in significant changes in the parameters of hydrocarbon-containing layers in the overlapping and / or underlying rock. For example, the underlying rock may contain shale or mudstone, however, during the processing at the place of occurrence, the underlying rock is not heated to pyrolysis temperatures. In separate cases, the overlapping and / or underlying rock may be partially permeable.

The term "formation fluids" refers to the fluids present in the formation and may include pyrolyzed fluid, synthesis gas, mobile hydrocarbons and water (steam). Formation fluids may include hydrocarbon fluids as well as non-hydrocarbon fluids. The term "mobile fluid" refers to fluids in a hydrocarbon containing formation that are capable of flowing as a result of heat treatment of the formation. The term "produced fluid" refers to fluids recovered from the formation.

A “heat source” can be any system for providing heating of at least a portion of a formation, essentially due to heat transfer by heat conduction and / or radiation. For example, a heat source may include electrically conductive material and / or electric heaters, such as an insulated conductor, an elongated element, and / or a conductor located in the channel. The heat source may also include systems that create heat by burning fuel received outside or within the formation. The systems may be surface burners, downhole gas burners, flameless distributed furnaces and natural distributed furnaces. In certain embodiments, heat supplied or generated by one or more heat sources may come from other energy sources. Other energy sources may directly heat the formation, or energy may be supplied to a transmission medium that directly or indirectly heats the formation. It should be understood that one or more heat sources that supply heat to the formation can use different energy sources. So, for example, for a particular formation, individual heat sources can supply heat through the use of electrically conductive materials, heaters with electrical resistance, some heat sources can supply heat through combustion, and some heat sources can supply heat from one or more sources (for example, due to chemical reactions, solar energy, wind energy, biomass or other sources of renewable energy). Chemical reactions may include an exothermic reaction (e.g., an oxidation reaction). The heat source may also include an electrically conductive material and / or a heater that provides heat to an area adjacent to and / or surrounding a heating location, such as a heater well.

A “heater” is any system or heat source for generating heat in a well or near an area of a wellbore. Heaters may be, but not limited to, electric heaters, burners, furnaces that react with material in the formation or from the formation, and / or a combination of them.

“Hydrocarbons”, in general, can be defined as molecules consisting primarily of carbon and hydrogen atoms. Hydrocarbons may also include other elements, such as, but not limited to, halogens, metal elements, nitrogen, oxygen and / or sulfur. Hydrocarbons may be, but are not limited to, kerogen, bitumen, pyrobitumen, oils, natural minerals, waxes and asphalts. Hydrocarbons may be located in or adjacent to mineral matrices in the ground. Matrices may include, but are not limited to, sedimentary rocks, sands, silicites, carbonates, diatomites, and other porous media. “Hydrocarbon fluids” are fluids that include hydrocarbons. Hydrocarbon fluids may include, contain or be contained in non-hydrocarbon fluids such as hydrogen, nitrogen, carbon monoxide, carbon dioxide, hydrogen sulfide, water and ammonia.

The term “in situ conversion process” refers to the process of heating a hydrocarbon containing formation by means of a heat source to increase the temperature of at least a portion of the formation above the pyrolysis temperature so that pyrolyzed fluid is formed in the formation.

The term “in situ heat treatment process” refers to the process of heating a hydrocarbon containing formation by using heat sources to increase the temperature of at least a portion of the formation above the temperature at which fluid mobility begins, light cracking and / or pyrolysis of the hydrocarbon containing material so that the formation occurs the formation of mobile fluids, fluids resulting from light cracking and / or pyrolyzed fluids.

The term "insulated conductor" refers to any elongated material capable of conducting electricity that is covered in whole or in part by an insulating material.

The term "nitride" refers to a compound of nitrogen and one or more other elements of the periodic table. Nitrides include, but are not limited to, silicon nitride, boron nitride, or alumina nitride.

The term "perforation" includes holes, slots, cutouts or openings in the wall of a channel, pipe, tube or other line for the passage of flow, allowing the stream to enter or exit the channel, pipe, tube or other line for the passage of the stream.

"Pyrolysis" - the destruction of chemical bonds due to heat. For example, pyrolysis may include converting the compound into one or more substances only by heating. To start pyrolysis, heat can be supplied to one of the sections of the formation.

The term "pyrolyzed fluid" or "pyrolysis products" refers to fluids obtained essentially during the pyrolysis of hydrocarbons. The fluid resulting from the pyrolysis reaction can be mixed with other fluids in the formation. A mixture is considered a pyrolyzed fluid or a pyrolyzed product. As used herein, the term “pyrolysis zone” refers to a volume of a formation (eg, a relatively permeable formation, such as a sand formation) that has reacted or is reacted to form a pyrolyzed fluid.

The term “thickness” of a layer refers to the thickness of the section of the layer in which the section extends perpendicular to the surface of the layer.

The term “wellbore” refers to a hole in a formation obtained by drilling or placing a channel in the formation. The wellbore may have a substantially circular cross-section or other cross-sectional shape. As used herein, the terms “well” or “hole”, as applied to a hole in a formation, may be used interchangeably with the term “well bore”.

The treatment of the formation can be carried out in various ways to obtain a wide range of different products. During the heat treatment process at the place of occurrence, different stages or processes of formation treatment can be used. In certain embodiments, one or more portions of a formation are mined by dissolution to extract soluble minerals from these portions. Extraction by dissolution can be carried out before, during and / or after the heat treatment process at the place of occurrence. In certain embodiments, the average temperature of one or more of the sites where mining is carried out by dissolution may be maintained below about 120 ° C.

In certain embodiments, one or more portions of the formation are heated to remove water from the sites and / or to remove methane and other volatile hydrocarbons from the sites. In certain embodiments, during the removal of water and volatile hydrocarbons, the average temperature may rise from ambient temperature to a temperature of about below 220 ° C.

In certain embodiments, one or more portions of the formation are heated to a temperature that results in mobility and / or light cracking of hydrocarbons in the formation. In some embodiments, the average temperature in one or more sections of the formation increases to the temperature of hydrocarbon mobility in the area (for example, to a temperature in the range from 100 ° C to 250 ° C, from 120 ° C to 240 ° C, or from 150 ° C to 230 ° C).

In certain embodiments, one or more portions of the formation are heated to a temperature at which pyrolysis reactions begin in the formation. In certain embodiments, the average temperature in one or more areas of the formation may increase to the temperature of pyrolysis of hydrocarbons in the areas (for example, to a temperature in the range from 230 ° C to 900 ° C, from 240 ° C to 400 ° C, or from 250 ° C up to 350 ° C).

Heating a hydrocarbon containing formation using a variety of heat sources can create temperature gradients around heat sources that increase the temperature of hydrocarbons in the formation to the desired temperature at the required heating rate. An increase in the temperature coefficient due to the range of mobility temperatures and / or the range of pyrolysis temperatures can affect the quality and quantity of formation fluids obtained from a hydrocarbon-containing formation. A slow increase in the temperature of the formation due to the range of mobility temperatures and / or the range of pyrolysis temperatures makes it possible to obtain high quality hydrocarbons from the formation with a high density value on the ANI scale. A slow increase in the temperature of the formation due to the range of mobility temperatures and / or the range of pyrolysis temperatures allows the extraction of a large amount of hydrocarbons used as hydrocarbon products from the formation.

In certain embodiments of the heat treatment at the place of occurrence, instead of a slow increase in temperature in the entire temperature range, one of the sections of the formation is heated to the required temperature. In certain embodiments, the desired temperature is 300 ° C, 325 ° C, or 350 ° C. Other temperature values may also be used as the required temperature.

Superposition of heat from heat sources allows you to create the required temperature in the formation relatively quickly and efficiently. The energy supplied to the formation from heat sources can be controlled to maintain the temperature of the formation, essentially at the level of the required temperature.

Mobile and / or pyrolyzed products can be extracted from the formation through production wells. In certain embodiments, the average temperature in one or more sections increases to mobility temperatures and hydrocarbons are produced from production wells. Average temperatures in one or more areas can be increased to pyrolysis temperatures after production by reducing mobility below a predetermined value. In certain embodiments, the average temperature at one or more sites can be increased to pyrolysis temperatures without significant production, until pyrolysis temperatures are reached. Formation fluids, including pyrolysis products, can be produced through production wells.

In certain embodiments, the average temperature at one or more sites can be increased to temperatures sufficient to ensure the production of synthesis gas after the onset of mobility and / or pyrolysis. In certain embodiments, the temperature of the hydrocarbons may be increased to temperatures sufficient to ensure production of synthesis gas without significant production until temperatures are sufficient to ensure production of synthesis gas. For example, synthesis gas can be produced in a temperature range of from about 400 ° C to about 1200 ° C, from about 500 ° C to about 1100 ° C, or from about 550 ° C to about 1000 ° C. Syngas can be produced from producing wells.

During the heat treatment processes at the place of occurrence, extraction by dissolution, removal of volatile hydrocarbons and water, mobility of hydrocarbons, pyrolysis of hydrocarbons, creation of synthesis gas and / or other processes can be carried out. In certain embodiments, individual processes can be carried out after the heat treatment processes at the place of occurrence. Such processes may include, but are not limited to, heat removal from heated areas, storage of fluids (e.g., water and / or hydrocarbons) in previously treated areas, and / or sequestration of carbon dioxide in previously treated areas.

Figure 1 shows a schematic view of one embodiment of a portion of a heat treatment system in situ for treating a hydrocarbon containing formation. The on-site heat treatment system may include barrier wells 200. Barrier wells are used to create a barrier around the treatment area. The barrier does not allow fluid flow to enter and / or exit the treatment area. Barrier wells include, but are not limited to, dehydration wells, vacuum wells, capture wells, injection wells, cementing wells, freeze wells, or a combination thereof. In certain embodiments, barrier wells 200 are dehydration wells. Dehydration wells can remove liquid water and / or prevent liquid water from entering a heated portion of the formation or into a heated formation. In the embodiment of FIG. 1, barrier wells 200 are shown extending along only one side of the heat sources 202, however typically barrier wells surround heat sources 202 that are or will be used to heat the treatment area of the formation.

Heat sources 202 are placed in at least a portion of the formation. Heat sources 202 may include insulated conductors such as heaters with in-channel conductors, surface burners, flameless distributed furnaces, and / or natural distributed furnaces. Heat sources 202 may also include other types of heaters. Heat sources 202 provide heat to at least a portion of the formation to heat hydrocarbons in the formation. Energy may be supplied to heat sources 202 via power lines 204. Power lines 204 may be structurally different, depending on the type of heat source or heat sources used to heat the formation. Power supply lines 204 for heat sources may supply electricity for electric heaters, may supply fuel for furnaces, or may supply liquid coolant circulating in the formation. In certain embodiments, electricity for the on-site heat treatment process may be supplied from a nuclear power plant or nuclear power plants. The use of atomic energy allows to reduce or eliminate the emissions of carbon dioxide released during the heat treatment at the place of occurrence.

When the formation is heated, the heat supplied to the formation can cause expansion of the formation and geomechanical movement. Heat sources may be included before, simultaneously with or during the dehydration process. Computer simulation allows you to simulate the reaction of the formation to heat. Computer simulation can be used to create a template and time sequence for actuating thermal heaters in the formation so that the geomechanical movement of the formation does not adversely affect the functioning of heat sources, production wells, and other equipment in the formation.

Heating the formation may cause an increase in permeability and / or porosity of the formation. An increase in permeability and / or porosity may occur due to a decrease in the mass of the formation due to evaporation and removal of water, hydrocarbon recovery and / or cracking. Fluid movement in the heated portion of the formation may occur faster due to increased permeability and / or porosity of the formation. Fluids in the heated portion of the formation can travel a considerable distance within the formation due to increased permeability and / or porosity. Such a significant distance, depending on various factors, can exceed 1000 m, since the permeability of the formation, the properties of the fluid, the temperature of the formation and the pressure gradient allow the movement of the fluid. The ability of the fluid to travel a significant distance within the formation allows the production wells 206 in the formation to be spaced sufficiently far apart.

Production wells 206 are used to remove formation fluids from the formation. In certain embodiments, production wells 206 include a heat source. A heat source from a producing well may heat one or more portions of a formation near or near a producing well. According to certain variants of the heat treatment process at the place of occurrence, the amount of heat supplied to the formation from the producing well per meter of the producing well is less than the amount of heat supplied to the formation from a heat source that heats the formation based on the meter of a heat source. Heat supplied to the formation from the production well may increase the permeability of the formation adjacent to the production well due to evaporation and removal of fluid in the liquid phase adjacent to the production well and / or due to an increase in the permeability of the formation adjacent to the production well due to the formation of macro and / or microcracks.

A production well may contain more than one heat source. The heat source at the bottom of the production well can be turned off if the superposition of heat from adjacent heat sources heats the formation sufficiently to balance the benefits provided by heating the formation in the production well. In certain embodiments, the heat source at the top of the production well may continue to be turned on after the heat source at the bottom of the production well is turned off. A heat source in the upper part of the production well may prevent condensation and outflow of formation fluid.

In certain embodiments, the heat source in the production well 206 allows for the removal of formation fluids from the formation in the vapor phase. The implementation of heating near or through the production well allows you to: (1) prevent the formation of condensate and / or outflow of drilling fluid when moving such drilling fluid in the production well near the overlapping rock, (2) increase the heat supply to the formation, (3) increase the productivity of the production well by compared to a production well without a heat source, (4) prevent condensation in compounds with a high carbon content (C6 hydrocarbons and higher) in the production well, and / or (5) increase the pr permeability of the formation adjacent to or near the production well.

Underground pressure in the formation may correspond to fluid pressure generated in the formation. As the temperature in the heated areas of the formation increases, the pressure on the heated area may increase due to thermal expansion of the fluids at the bed, increasing the formation of fluids and the evaporation of water. Adjusting the rate of fluid removal from the formation allows you to adjust the pressure in the formation. The pressure in the reservoir can be measured at several different points, for example, near or near producing wells, near or near heat sources, or near control and regulatory wells.

In individual hydrocarbon containing formations, hydrocarbon production from the formation is not possible until at least a portion of the hydrocarbons in the formation is mobile and / or pyrolyzed. Formation fluids can be produced from the formation after the formation fluid has an appropriate quality. In certain embodiments, appropriate quality assumes a density in degrees of API at least about 20 °, 30 °, or 40 °. The inability to produce until at least a portion of the hydrocarbons becomes mobile and / or pyrolyzed allows the conversion of heavy hydrocarbons to light hydrocarbons to be increased. The impossibility of initial production can minimize the production of heavy hydrocarbons from the reservoir. The production of significant amounts of heavy hydrocarbons may require the use of expensive equipment and / or shorten the life of the production equipment.

In individual hydrocarbon containing formations, hydrocarbons in the formation may be heated to mobility temperatures and / or pyrolysis temperatures before substantial permeability in the heated portion of the formation is achieved. The initial lack of permeability may prevent the formation of fluid fluids into production wells 206. During pre-heating, the fluid pressure in the formation may increase near heat sources 202. The increased fluid pressure can be relieved, monitored, changed and / or controlled using one or non-slip heat sources 202. For example, selected heat sources 202 or individual pressure relief wells may include pressure relief valves to remove part of the formation from the formation. luids.

In certain embodiments, the pressure created by the expansion of mobile fluids, pyrolyzed fluids, or other fluids generated in the formation can be maintained at least to expand the open channel into production wells 206 or any other depression that may not yet be in the formation. The increase in fluid pressure may continue up to lithostatic pressure. As fluid pressure approaches lithostatic pressure, cracks may form in the hydrocarbon containing formation. For example, cracks can form from heat sources 202 to production wells 206 in a heated portion of the formation. The appearance of cracks in the heated area may lead to some pressure drop in the area. The pressure in the formation may be kept below a predetermined pressure to prevent unwanted production, formation of cracks in the overburden or underlying rock, and / or coking of hydrocarbons in the formation.

After reaching the mobility temperature and / or pyrolysis temperature and obtaining production permit from the formation, the pressure in the formation can be changed to change and / or control the composition of the fluid produced from the formation, to regulate the percentage of condensed fluid compared to non-condensable fluid in the reservoir fluid and / or to control the density in degrees of API produced from the formation fluid. For example, a decrease in pressure can lead to an increase in production of a condensable fluid component. The condensable fluid component may contain a larger percentage of olefins.

According to certain options for the implementation of heat treatment processes at the place of occurrence, the pressure in the formation can be kept high enough to improve the production of formation fluids with a density in degrees of API over 20 °. Maintaining increased pressure in the formation can prevent the formation of sediment during heat treatment at the place of occurrence. Maintaining high pressure allows you to reduce or eliminate the need for compression of reservoir fluids during transportation of fluids through the collector channels to treatment facilities.

Maintaining increased pressure in the heated section of the formation surprisingly allows you to produce more hydrocarbons with higher quality and relatively low molecular weight. The pressure can be maintained so that the produced fluid has a minimum number of compounds above a given carbon number. A given carbon number can be no more than 25, no more than 20, no more than 12 or no more than 8. Some compounds with a high carbon number can be in the formation in the form of steam and can be removed from the formation together with steam. Maintaining increased pressure in the formation may inhibit the conversion of high carbon number compounds and / or polycyclic hydrocarbon compounds into steam. High carbon number compounds and / or polycyclic hydrocarbon compounds may remain in the formation in the liquid phase for a significant period of time. A significant period of time allows the compounds to pyrolyze, forming compounds with a lower carbon number.

It is believed that the formation of hydrocarbons with a relatively low molecular weight occurs partly due to the autogenous generation and reaction of hydrogen in the area of the hydrocarbon containing formation. For example, maintaining elevated pressure can cause the hydrogen generated during pyrolysis to transfer into the liquid phase within the formation. Heating the site to a pyrolysis temperature can pyrolyze hydrocarbons in the formation, creating pyrolyzed fluids in the liquid phase. Generated pyrolyzed fluid components in the liquid phase may include double bonds and / or radicals. Hydrogen (H ₂ ) in the liquid phase can reduce double bonds in the generated pyrolyzed fluids, thereby reducing the possibilities for polymerization or the formation of long chain compounds from the generated pyrolyzed fluids. In addition, H ₂ can also neutralize radicals in the generated pyrolyzed fluids. H ₂ in the liquid phase can prevent the generated pyrolyzed fluids from reacting with each other and / or other components of the formation.

Formation fluid produced from production wells 206 may be transported through manifold pipes 208 to treatment facilities 210. Formation fluids may also be produced from heat sources 202. For example, fluid may be produced from heat sources 202 to control pressure in the formation near heat sources. Fluid produced from heat sources 202 can be transported through pipes or tubes to a manifold pipe 208, or produced fluid can be transported through pipes or tubes directly to treatment plants 210. Treatment plants 210 may include separator devices, reaction devices, enrichment devices, fuel cells, turbines, storage tanks and / or other systems and devices for processing produced reservoir fluids. Wastewater treatment plants allow you to get transport fuel from at least part of the hydrocarbons produced from the reservoir. In certain embodiments, the transport fuel may be aviation fuel, such as JP-8.

An insulated conductor can be used as an electric heating element of a heater or heat source. The insulated conductor may include an internal electrical conductor (core) surrounded by an electrical insulator, and an external electrical conductor (sheath). An electrical insulator may include mineral insulation (e.g., magnesium oxide) or other electrical insulation.

In some embodiments, an insulated conductor is placed in an opening in a hydrocarbon containing formation. In certain embodiments, an insulated conductor is placed in an open hole in a hydrocarbon containing formation. The placement of an insulated conductor in an open hole in a hydrocarbon containing formation allows heat to be transferred from the insulated conductor to the formation due to radiation, as well as due to conductivity. Using an open hole makes it easier, if necessary, to remove the insulated conductor from the well.

In certain embodiments, an insulated conductor is placed inside the casing in the formation; can be cemented inside the reservoir; or it can be filled with sand, gravel or other loose material inside the hole. The insulated conductor can rest on a support element located inside the hole. The support member may be a cable, rod, or conduit (e.g., pipe). The support element may be made of metal, ceramic, inorganic material, or a combination of them. Since portions of the support member may be exposed to formation fluids and heat during use, the support member may be chemically stable and / or heat resistant.

To connect the insulated conductor with the support element at different lengths of the length of the insulated conductor, bundles, spot welding and / or other types of connectors can be used. The support element can be attached to the wellhead at the top of the formation. In certain embodiments, the conductor has sufficient strength, so the support member may not be used. Quite often, an insulated conductor can have at least flexibility that prevents damage to the conductor as a result of thermal expansion due to temperature changes.

In some embodiments, insulated conductors are placed in wellbores without support elements and / or centralizers. An insulated conductor without supporting elements and / or centralizers can have such temperature and corrosion resistance, creep strength, length, thickness (diameter) and metallurgical composition that prevent the failure of the insulated conductor during use.

FIG. 2 shows a perspective view of an end portion of an insulated conductor 212 in one embodiment. The insulated conductor 212 may have any desired cross-sectional shape, for example, including, but not limited to, round (as in FIG. 2), triangular, ellipsoidal, rectangular, hexagonal or irregular. In certain embodiments, the insulated conductor 212 includes a core 214, an electrical insulator 216, and a sheath 218. The core 214 may resistively heat up when an electric current passes through the core. An alternating or time-varying and / or direct current can be used to supply power to the core 214 so that resistive heating of the core occurs.

In certain embodiments, the insulator 216 prevents leakage of current and an arcing breakdown on the shell 218. The insulator 216 can transfer heat generated in the core 214 to the shell 218. The shell 218 can radiate or conduct heat to the formation. In some embodiments, the length of the insulated conductor 212 is 1000 m or more. Longer or shorter insulated conductors can also be used to meet the needs of specific applications. The dimensions of the core 214, the insulator 216 and the sheath 218 of the insulated conductor 212 can be selected so that the insulated conductor has sufficient strength to be self-sufficient even at upper operating temperature limits. Such insulated conductors can be suspended at the wellhead or on supports located near the boundary between the overburden and the hydrocarbon containing formation without the use of supporting elements entering the hydrocarbon containing formation together with the insulated conductors.

The insulated conductor 212 may be designed to operate at a power level of up to about 1650 W / m or more. In certain embodiments, when the formation is heated, insulated conductor 212 operates at a power level of about 500 W / m to about 1150 W / m. The insulated conductor can be designed so that the maximum voltage level at normal operating temperature does not cause significant thermal and / or electrical breakdowns of the insulator 216. The insulated conductor 212 can be designed so that the temperature of the sheath 218 does not exceed a value that leads to a significant decrease anticorrosive properties of the shell material. In some embodiments, the insulated conductor 212 may be designed so that its temperature reaches values in the range of about 650 ° C to about 900 ° C. Insulated conductors with different operating ranges can be created to match specific operating parameters.

Figure 2 shows an insulated conductor 212 with a single core 214. In some embodiments, the insulated conductor 212 has two or more cores 214. For example, one insulated conductor may have three cores. The core 214 may be made of metal or other electrically conductive material. The materials used to make core 214 include, but are not limited to, nichrome, copper, nickel, carbon steel, stainless steel, or a combination thereof. In individual embodiments, the core 214 is selected so that at the operating temperature it has such a diameter and resistance that its resistance, calculated according to Ohm's law, allows it to be electrically and structurally stable for the selected power dissipation per meter, heater length and / or maximum voltage allowed for core material.

In certain embodiments, the core 214 is made of different materials along the length of the insulated conductor 212. For example, the first portion of the core 214 may be made of a material having a significantly lower resistance than the second portion of the core. The first section may be located near the formation layer, which does not need to be heated to the same high temperature as the second formation layer adjacent to the second section. The resistance of different sections of the core 214 can be adjusted due to the variable diameter and / or due to the manufacture of sections of the core from different materials.

Electrical insulator 216 may be made of various materials. Commonly used powder materials may include, but are not limited to, MgO, Al ₂ O ₃ , zirconia, BeO, various chemical spinel variants, as well as combinations thereof. MgO can provide good thermal conductivity and electrical insulating properties. Necessary electrical insulation properties include low leakage current and high dielectric strength. A low leakage current reduces the probability of thermal breakdown, and a high dielectric strength reduces the likelihood of an arc breakdown around the insulator. Thermal breakdown can occur if the leakage current causes a progressive increase in the temperature of the insulator, which also leads to an arc breakdown around the insulator.

Shell 218 may be an external metal layer or an electrically conductive layer. Shell 218 may be in contact with hot formation fluids. Sheath 218 may be made of a material having high corrosion resistance at elevated temperatures. Alloys that can be used for shell 218 in the desired operating temperature range include, but are not limited to, stainless steel 304, stainless steel 310, Incoloy® 800, and Inconel® 600 (Inco Alloys International, Hatington, State West Virginia, USA). The thickness of the sheath 218 must be sufficient to serve three to ten years in a hot and corrosive environment. The thickness of the shell 218, in General, can range from about 1 mm to about 2.5 mm For example, as a shell 218, providing high chemical resistance to hydrogen sulfide corrosion in the heated zone of the formation for a period of more than 3 years, an external layer of stainless steel 310 with a thickness of 1.3 mm can be used. To meet the needs of specific applications, a shell of greater or lesser thickness can be used.

One or more insulated conductors can be placed inside the hole in the formation to create a heat source or heat sources. To heat the formation, electric current can be passed through each of the insulated conductors located in the hole. Alternatively, an electric current may be passed through some of the insulated conductors located in the hole. Unused conductors can be used as spare heaters. Insulated conductors can be electrically connected to a power source in any conventional manner. Each end of the insulated conductor may be interfaced with input cables passing through the wellhead. Such an arrangement usually has a 180 ° bend (“hairpin” bend) or a turn near the bottom of the heat source. For an insulated conductor with a bend of 180 ° or rotation, a lower end termination may not be required, however, a bend of 180 ° or rotation may be an electrically and / or structurally weak link of the heater. Insulated conductors can be electrically connected to each other in series, in parallel or in series-in parallel. In certain embodiments of the heat sources, electric current can enter the conductor of the insulated conductor and can be returned through the shell of the insulated conductor by connecting the core 214 to the shell 218 (see FIG. 2) at the bottom of the heat source.

In certain embodiments, three insulated conductors 212 are electrically connected to a power source in the form of a 3-phase star connection. Figure 3 shows an embodiment of three insulated conductors in the hole of an underground formation connected by a star. Figure 4 shows an embodiment of three insulated conductors 212 extracted from a hole 220 in the formation. No bottom connections for three insulated conductors in a star arrangement are required. Alternatively, all three insulated conductors in the star arrangement can be interconnected near the bottom of the hole. The connection can be made directly at the ends of the heating sections of insulated conductors or at the ends of cold studs (sections with lower resistance) connected to the heating sections at the bottom of the insulated conductors. Bottom joints can be made using sealed containers filled with insulator or containers filled with epoxy. The insulator may have the same composition as the insulator used as an electrical insulator.

Three insulated conductors 212 of FIGS. 3 and 4 can be connected to the support element 222 using centralizers. 224. Alternatively, insulated conductors 212 may be tied directly to the support member 224 using metal clamps. Centralizers 224 allow you to hold in place and / or prevent the movement of insulated conductors 212 along the support elements 222. Centralizers 224 can be made of metal, ceramic or a combination of them. The metal may be stainless steel or any type of metal capable of withstanding a corrosive and high temperature environment. In certain embodiments, the centralizers 224 are curved metal strips welded to the support member at intervals of less than about 6 m. The ceramic material used in the centralizers 224 may include, but is not limited to, Al ₂ O ₃ , MgO, or another electrical insulator. Centralizers 224 may hold the insulated conductors 212 in place on the support members 222 so as to prevent the insulated conductors from moving at the operating temperatures of the insulated conductors. The insulated conductors 212 may also have some flexibility in order to withstand the expansion of the support member 222 when heated.

The support member 222, the insulated conductor 212, and the centralizers 224 can be placed in the opening 220 of the hydrocarbon layer 226. The insulated conductors 212 can be connected to the lower conductor connection 228 using cold pins 230. The lower conductor connection 228 can electrically connect all insulated conductors 212 to each other friend. The lower conductor connection 228 may include materials that are electrically conductive and do not melt at the temperature created in the hole 220. The cold stud 230 may be an insulated conductor with lower electrical resistance than the insulated conductor 212.

The lead-in conductor 232 may be connected to the wellhead 234 to supply power to the insulated conductor 212. The lead-in conductor 232 may be made of a relatively low electrical resistance conductor so that the passage of electric current through the lead-in conductor does not cause significant heating. In certain embodiments, the lead-in conductor is a stranded copper wire with rubber or polymer insulation. In certain embodiments, the lead-in conductor is a copper core and mineral insulated conductor. The lead-in conductor 232 may be connected to the wellhead 234 at surface 236 using a sealing flange located between the overburden 238 and surface 236. The sealing flange may prevent fluid from flowing out through opening 220 onto surface 236.

In certain embodiments, the lead-in conductor 232 is connected to the insulated conductor 212 by a junction conductor 240. The junction conductor 240 may be part of an insulated conductor 212 with lower resistance. The adapter conductor 240 may be called the “cold pin” of the insulated conductor 212. The adapter conductor 240 can be designed to dissipate from about one tenth to about one fifth of the power per unit length, similar to how dissipation per unit length in the main section insulated conductor 212. The length of the transition conductor 240 is typically from about 1.5 m to about 15 m, although the length may be longer or shorter to suit the needs of specific applications. In one embodiment, the transition conductor conductor 240 is made of copper. The electrical insulator of the transition conductor 240 may be the same type of electrical insulator that is used in the main heating section. The sheath of the transition conductor 240 may be made of a corrosion-resistant material.

In some embodiments, the transition conductor 240 is connected to the lead-in conductor 232 via a splice or other connection. The splice can also be used to connect the adapter conductor 240 to the insulated conductor 212. The splice can withstand temperatures equal to half the operating temperature in the target area. The density of electrical insulation in the splice in many cases must be high enough to withstand the required temperature and operating voltage.

In individual embodiments, as shown in FIG. 3, packaging material 242 is placed between the overburden casing 244 and the opening 220. In some embodiments, the overburden casing 244 may be secured in the overburden with reinforcing material 246. The packaging material 242 may prevent fluid from escaping holes 220 to surface 236. Reinforcing material 246 may include, for example, Portland Class G or Class H cement mixed with silica flour to improve temperature performance teles, slag or silica flour and / or a mixture of them. In certain embodiments, the reinforcing material 246 extends radially from about 5 cm to about 25 cm wide.

As shown in FIGS. 3 and 4, the support member 222 and lead-in conductor 232 may be connected to the wellhead 234 at the surface of the formation. Surface conductor 248 may surround the reinforcing material 246 and connect to the wellhead 234. The surface conductors according to various embodiments can go into the hole of the formation to a depth of about 3 m to about 515 m. Alternatively, the surface conductor can go into the formation to a depth of about 9 m. Electric current can be supplied to the insulated conductor 212 from the power source to create heating due to the electrical resistance of the insulated conductor. The heat generated by the three insulated conductors 212 may enter the opening 220 to heat at least a portion of the hydrocarbon layer 226.

The heat generated by insulated conductors 212 can heat at least one of the sections of the hydrocarbon containing formation. In certain embodiments, heat is transferred to the formation, essentially due to the radiation of the generated heat into the formation. Part of the heat can be transferred due to conduction or convection of heat due to the presence of gases in the hole. The hole may be an open hole, as shown in FIGS. 3 and 4. An open hole allows avoiding costs associated with thermal cementing of the heater in the formation, costs associated with casing and / or packaging costs of the heater inside the hole. In addition, heat transfer due to radiation is usually more efficient than conductivity, since heaters can be used at lower temperatures than in an open wellbore. Heat transfer through thermal conductivity at the start of a heat source can be increased by adding gas to the hole. Absolute gas pressure can be maintained up to values above 27 bar. The gas may include, but is not limited to, carbon dioxide and / or helium. An insulated conductor heater in an open wellbore may preferably expand or contract unhindered depending on thermal expansion or contraction. The insulated conductor heater may preferably be removed or moved from an open wellbore.

In some embodiments, the insulated conductor heater assembly is mounted or removed using a winding assembly. For the simultaneous installation of an insulated conductor and a support element, more than one winding unit can be used. Alternatively, the support element can be installed using a coiled tubing installation. Heaters can be unwound and connected to the support as the support is placed in the well. The electric heater and the support element can be unwound from the winding units. Separators may be connected to the support member and the heater along the length of the support member. For additional elements of electric heaters, additional winding units can be used.

Temperature limited heaters may have such an arrangement and / or may include materials that have the ability to automatically limit the temperature of heaters when certain temperatures are reached. Examples of temperature limited heaters can be found in US Pat. No. 6,688,387 to Wellington et al .; 6,991,036 in the name of Sami-Dindoruk et al .; 6,698,515 addressed to Karanikas et al .; 6,880,633 addressed to Wellington et al .; 6,782,947 addressed to Ruffignac et al .; 6,991,045 in the name of Vinegar et al .; 7,073,578 in the name of Vinegar et al .; 7,121,342 in the name of Vinegar et al .; 7,320,364 in the name of Fairbanks; 7,527,094 addressed to Mackenzie et al .; 7,584,789 addressed to Mo et al .; 7,533,719 to Hinson et al .; and 7,562,707 in the name of Miller; US Published Patent Applications No. 2009-0071652 to Vinegar et al .; 2009-0189617 in the name of Bern et al .; 2010-0071903 addressed to Prince Wright et al .; and also 2010-0096137 in the name of Nguyen et al. Temperature limited heaters are designed to operate with a variable frequency current (for example, alternating current with a frequency of 60 Hz) or with modulated direct current.

In some embodiments, temperature limited heaters utilize ferromagnetic materials. Ferromagnetic materials can automatically limit the temperature near or near the Curie temperature of the material and / or the phase transformation temperature range to reduce the amount of heat generated when a time-varying current is applied to the material. In some embodiments, the ferromagnetic material automatically limits the temperature of the heater with a temperature limit at a predetermined temperature approaching the Curie temperature and / or in the phase transformation temperature range. In some embodiments, the target temperature differs from the Curie temperature and / or the phase transformation temperature range by about 35 ° C, about 25 ° C, about 20 ° C, or about 10 ° C. In some embodiments, the ferromagnetic materials are combined with other materials (for example, materials with increased conductivity, materials with increased strength, corrosion-resistant materials, or a combination of them) to obtain various electrical and / or mechanical properties. Certain parts of a temperature-limited heater may have lower resistance (due to different geometric shapes and / or the use of ferromagnetic and / or non-ferromagnetic materials) than other parts of a temperature-limited heater. The manufacture of temperature-limited heater parts from different materials and / or different sizes allows you to get the necessary heat transfer from each part of the heater.

Temperature limited heaters can be more reliable than other heaters. Temperature-limited heaters can less often break or fail due to hot spots in the formation. In certain embodiments, temperature limited heaters allow substantially uniform heating of the formation. In certain embodiments, temperature-limited heaters are capable of heating the formation more efficiently by operating at a higher average heat transfer along the entire length of the heater. A temperature-limited heater operates with a higher average heat dissipation over the entire length of the heater due to the fact that the power supply to the heater does not need to be reduced throughout the heater, as is the case with conventional heaters with constant active power in watts, if the temperature is point of the heater exceeds or may exceed the maximum operating temperature of the heater. The heat transfer of the temperature limited parts of the heater, approaching the Curie temperature and / or the temperature range of the phase transformation of the heater, automatically decreases without controlled regulation of the time-varying current supplied to the heater. Heat transfer is automatically reduced by changing the electrical properties (for example, electrical resistance) of the parts of the heater with temperature limitation. Therefore, a temperature limited heater gives more power over a longer period of the heating process.

In some embodiments, a system including temperature limited heaters initially provides a first heat transfer and then provides a reduced (second) heat transfer that approaches, is near or exceeds the Curie temperature and / or temperature range of the phase transformation of the electrical resistive part of the heater when the heater is energized with temperature limitation, time-varying current. The first heat transfer is heat transfer with a temperature below which a temperature-limited heater begins to automatically limit. In certain embodiments, the first heat transfer is heat transfer, the temperature of which is about 50 ° C, about 75 ° C, about 100 ° C, or about 125 ° C below the Curie temperature and / or the temperature range of the phase transformation of the ferromagnetic material in the heater with the restriction temperature.

A temperature-limited heater can be powered by a time-varying current (alternating current or modulated direct current) supplied to the wellhead. The wellhead may include a power source or other components (eg, modulation components, transformers and / or capacitors) used to supply power to the temperature limited heater. A temperature limited heater may be one of many heaters used to heat a portion of a formation.

In some embodiments, the temperature limited heater includes a conductor acting as a surface effect heater or a similar effect heater when a time-varying current is supplied to the conductor. The surface effect limits the depth of current penetration into the conductor. In ferromagnetic conductors, the magnetic permeability of the conductor prevails over the surface effect. The relative magnetic permeability of the ferromagnetic materials is usually from 10 to 1000 (for example, the relative magnetic permeability of the ferromagnetic materials is usually at least 10 and may be at least 50, 100, 500, 1000 or more). As the temperature of the ferromagnetic material rises above the Curie temperature or phase transformation temperature range and / or as the supplied electric current increases, the magnetic permeability of the ferromagnetic material essentially decreases and the depth of the surface layer increases rapidly (for example, the depth of the surface layer increases inversely with the square root of magnetic permeability). A decrease in magnetic permeability leads to a decrease in the resistance to alternating current or modulated direct current of the conductor near, near or above the Curie temperature, the temperature range of the phase transformation and / or as the supplied electric current increases. When a temperature limited heater is supplied from a substantially constant current source, the heat transfer of parts of the heater whose temperature approaches, reaches or exceeds the Curie temperature and / or phase transformation temperature range may decrease. In temperature limited heater sections, the temperature of which is not near or near the Curie temperature and / or the phase transformation temperature range, heating with a surface effect may prevail, which allows the heater to provide high heat transfer due to the high resistive load.

The advantage of using a temperature limited heater to heat hydrocarbons in the formation is that the conductor is selected so that it reaches the Curie temperature and / or the phase transformation temperature range when operating in the required temperature range. Functioning within the required temperature range allows for significant heat supply to the formation while maintaining the temperature of the heater with temperature limitation, as well as other equipment below the calculated temperature limits. The calculated temperature limits are the temperatures at which properties such as corrosion, creep and / or deformation begin to have a negative effect. Temperature-limited properties of the temperature-limited heater prevent overheating or burnout of the heater near the “hot spots” of the low thermal conductivity formation. In certain embodiments, a temperature limited heater is capable of reducing or controlling heat transfer and / or withstanding temperatures above 5 ° C, 37 ° C, 100 ° C, 250 ° C, 500 ° C, 700 ° C, 800 ° C, 900 ° C or above 1131 ° C, depending on the materials used in the heater.

A temperature-limited heater allows more heat to be supplied to the formation compared to heaters with constant power in watts, since the energy supply to the temperature-limited heater does not need to be limited, taking into account the areas of low thermal conductivity adjacent to the heater. For example, on Green River oil shales, the thermal conductivity of the poorest oil shale layers and the richest oil shale layers is at least 3 times different. When heating such a formation, a temperature limited heater essentially delivers more heat to the formation than a conventional heater, which is limited by the temperature of the layers with low thermal conductivity. During heat transfer along the entire length of a traditional heater, it is necessary to take into account layers with low thermal conductivity so that the heater does not overheat in layers with low thermal conductivity and does not burn out. The heat transfer near layers with low thermal conductivity heated to a high temperature will decrease with a temperature limited heater, then the remaining parts of the temperature limited heater that are not heated to high temperature will still provide high heat transfer. Since heaters have a long length for heating hydrocarbon reservoirs (for example, at least 10 m, 100 m, 300 m, 500 m, 1 km or more, up to 10 km), most of the temperature limited heater can function below the Curie temperature and / or the temperature range of the phase transformation, while only the temperature of individual sections of the heater with temperature limitation will approach or be near the Curie temperature and / or the temperature range of the phase transformation.

Using temperature limited heaters allows efficient heat transfer to the formation. Efficient heat transfer reduces the time required to heat the formation to the desired temperature. For example, on Green River oil shales, the duration of heating before the start of pyrolysis usually takes from 9.5 to 10 years when traditional heaters with constant power in watts are placed in heating wells with an interval of 12 m. With the same distance between the heaters, the use of temperature limited heaters allows achieving a higher average heat transfer while maintaining the temperature of the heating equipment below the calculated maximum temperature of the equipment. Pyrolysis in the formation may begin earlier with a higher average heat transfer provided by temperature limited heaters, compared with lower heat transfer provided by heaters with constant power in watts. For example, on Green River oil shales, pyrolysis can begin after 5 years when using temperature limited heaters located in heating wells with a gap of 12 m. Temperature limited heaters avoid hot spots due to non-observance of the distance between wells or drilling of heating wells too close to each other. In some embodiments, temperature limited heaters allow over time to increase the power of heating wells that are too far apart from each other or to limit the power of heating wells that are too close to each other. Temperature-limited heaters also provide more power in the areas adjacent to the overburden and the underlying bed to compensate for temperature losses in these areas.

Temperature limited heaters can preferably be used in different types of formations. For example, in oil sands formations or in relatively permeable formations containing heavy hydrocarbons, temperature limited heaters can be used to maintain a controlled low output temperature to reduce fluid viscosity, achieve fluid mobility and / or increase radial fluid flow near or near the wellbore wells in the reservoir. Temperature limited heaters can be used to prevent excessive coking due to excessive heating in the wellbore area of the formation.

In certain embodiments, the use of temperature limited heaters eliminates or reduces the need for expensive electronic circuits for temperature control. For example, the use of temperature limited heaters eliminates or reduces the need for temperature monitoring and / or the need to use thermocouples on heaters to monitor possible overheating in hot spots.

Temperature limited heaters can be used in conduit heaters. In certain embodiments of conduit heaters, most resistive heat is generated in the conductor, and heat is transferred to the conduit through radiation, heat conduction, and / or convection. In certain embodiments of conduit heaters, most of the resistive heat is generated in the conduit.

In certain embodiments, a relatively thin conductive layer is used to provide most of the electrically resistive heat transfer of the temperature limited heater at temperatures reaching or approaching the Curie temperature and / or temperature range of the phase transformation of the ferromagnetic conductor. Such a temperature limited heater can be used as a heating element of an insulated conductor heater. The heating element of the heater with an insulated conductor can be located inside the braid, and between the braid and the heating element there is an insulating layer.

Mineral insulated cables (MI) (insulated conductors) designed for underground use, for example, in certain applications for heating hydrocarbon-containing formations, have an increased length, can have an increased outer diameter and can be used at higher voltages and temperatures compared to with generally accepted values for mineral insulated cables. For such underground applications, it may be necessary to connect several mineral-insulated cables to produce mineral-insulated cables of sufficient length extending to such a depth and distance that it is possible to efficiently heat the subterranean formation and connect areas with different functionality, for example, connect input cables to sections heater. For such long heaters, an increased voltage is also required to supply a sufficient amount of electricity to the farthest ends of the heaters.

Conventional spliced mineral insulated cable designs are usually not suitable for voltages above 1000 V, more than 1500 V or more than 2000 V and cannot function for a long time without failures at elevated temperatures, for example, above 650 ° C (about 1200 ° F), above 700 ° C (approximately 1290 ° F) or above 800 ° C (approximately 1470 ° F). For such applications with high voltage and high temperature, it is usually necessary to compress the mineral insulating material in the splicing so that it is located as close as possible to the level of compression or is above the level of compression directly in the insulated conductor (cable with mineral insulation).

The relatively large outer diameter and long mineral-insulated cable lengths for some applications require that the cable splices be carried out with the cables horizontal. There are splices for other mineral insulated cable applications that have been laid horizontally. A similar technique usually involves making a small hole through which mineral insulation (for example, powdered magnesium oxide) is filled into a splicer and slightly compressed by vibration or ramming. Such methods do not provide sufficient compression of the mineral insulation, or even, in some cases, do not provide any compression of the mineral insulation and therefore are not suitable for splicing when used under high stress conditions required for such underground applications.

Therefore, there is a need for splices for insulated conductors, which, despite their simplicity, can function at high voltages and temperatures in underground conditions for a long time, without breakage. In addition, to prevent breakage of the splice under the weight load and temperatures to which cables can be exposed underground, the splice must have high bending strength and tensile strength. You can also use technologies and methods to reduce the intensity of the electric field in the splices in such a way as to reduce the loss currents in the splices and to increase the interval between the operating voltage and electrical breakdown. Reducing the intensity of the electric field allows you to increase the voltage and the operating temperature range for splices.

Figure 5 shows a side view in cross section of one embodiment of a fitting for connecting insulated conductors. The fitting 250 is a splice or connector for connecting insulated conductors 212A, 212B. In some embodiments, fitting 250 includes a sleeve 252 and a housing 254A, 254B. The housings 254A, 254B may be splicing housings, couplings housings, or connector housings. The sleeve 252 and the casings 254A, 254B may be made of mechanically durable, electrically conductive material, such as, but not limited to, stainless steel. The sleeve 252 and the casings 254A, 254B may have a cylindrical or polygonal shape. The sleeve 252 and the casings 254A, 254B may have rounded edges, narrowing transitions of the diameter, other signs or combinations of them, allowing to reduce the intensity of the electric field in the fitting 250.

The fitting 250 can be used to connect (spliced) the insulated conductor 212A with the insulated conductor 212B while maintaining the mechanical and electrical integrity of the shells (braids), insulation and cores (conductors) of the insulated conductors. Fitting 250 may be used to connect heat-insulating conductors to non-heat-insulating conductors, to connect heat-insulating conductors to other heat-insulating conductors, or to connect heat-insulating conductors to other non-heat-insulating conductors. In certain embodiments, more than one fitting 250 is used to couple multiple heat generating and non heat generating insulated conductors and produce a long insulated conductor.

Fitting 250 can be used to connect insulated conductors of different diameters, as shown in FIG. 5. For example, insulated conductors may have a core (conductor) of different diameters, a sheath (braid) of different diameters, or a combination of different diameters. Fitting 250 can also be used to connect insulated conductors of different metallurgical composition, with different types of insulation or a combination of these properties.

As shown in FIG. 5, the casing 254A is connected to the sheath (braid) 218A of the insulated conductor 212A, and the casing 254B is connected to the sheath 218B of the insulated conductor 212B. In some embodiments, shrouds 254A, 254B are welded, soldered, or otherwise permanently fixed to insulated conductors 212A, 212B. In certain embodiments, the shrouds 254A, 254B are temporarily or permanently attached to the sheaths 218A, 218B of insulated conductors 212A, 212B (for example, connected by thread or glue). The fitting 250 may be centered between the end portions of the insulated conductors 212A, 212B.

In some embodiments, the internal volumes of the sleeve 252 and the housings 254A, 254B are substantially filled with electrical insulating material 256. In some embodiments, “substantially filled” refers to a volume or volumes of fully or almost completely filled electrical insulating material, essentially without macroscopic voids in volume or volumes. For example, a term that is substantially filled may refer to filling almost the entire volume with an insulating material having a certain porosity due to microscopic voids (e.g., porosity up to 40%). The insulating material may include magnesium oxide, talc, powders of ceramic materials (for example, boron nitride), a mixture of magnesium oxide and other electrical insulators (for example, up to 50 weight percent boron nitride), ceramic cement, mixtures of powders of ceramic materials with individual non-ceramic materials (such as tungsten sulfide (WS2)), or mixtures thereof. For example, magnesium oxide can be mixed with boron nitride or another electrical insulator to improve the fluidity of the electrical insulation material, improve the dielectric characteristics of the electrical insulation material, or increase the flexibility of the fitting. In certain embodiments, the insulating material 256 is a material similar to the electrical insulation used inside at least one of the insulated conductors 212A, 212B. The insulating material 256 may have substantially the same dielectric characteristics as the electrical insulation used inside at least one of the insulated conductors 212A, 212B.

In some embodiments, the first sleeve 252 and the casings 254A, 254B are configured such that they (for example, are connected or in manufacture) are placed or immersed in the electrical insulation material 256. The placement of the sleeve 252 and the casings 254A, 254B in the electrical insulation material 256 prevents the formation of open space in the internal volume of the parts. The sleeve 252 and the casings 254A, 254B have open ends for passage through them of insulated conductors 212A, 212B. The diameter of such open ends is slightly larger than the outer diameter of the shell of insulated conductors.

In some embodiments, the cores 214A, 214B of the insulated conductors 212A, 212B are interconnected in the sleeve 258. The shells and insulation of the insulated conductors 212A, 212B can be cut or stripped to expose the cores 214A, 214B to the required length before connecting the cores. The coupling 258 may be located in the insulating material 256, inside the sleeve 252.

The coupling 258 can connect the cores 214A, 214B to each other, for example, by pressing, crimping, soldering, welding or other technologies known from the prior art. In certain embodiments, core 214A is made from a material different from core material 214B. For example, core 214A may be copper, while core 214B may be stainless steel, carbon steel, or alloy 180. In such embodiments, special welding methods may be used to connect the cores to each other. For example, the tensile strength and / or yield strength of the cores should be as close as possible so that the joint between the cores does not break down over time or as it is used.

In certain embodiments, the copper core may be hardened before being connected to a carbon steel or alloy core 180. In certain embodiments, the cores are continuously welded using filler material (eg, filler metal) between the cores of different materials. For example, Monel® nickel alloys (Special Metals Corporation, New Hartford, NY, USA) can be used as filler materials. In certain embodiments, before the welding process, copper cores are smeared (melted and mixed) with filler material.

In one embodiment, the insulated conductors 212A, 212B are connected using the fitting 250 first by putting the jacket 254A on the sheath 218A of the insulated conductor 212A, and then putting the jacket 254B on the sheath 218B of the insulated conductor 212B. The casings are worn on the shells so that the ends of the large diameter casing are facing the ends of the insulated conductors. The sleeve 252 can be worn on an insulated conductor 212B so that it adjoins the casing 254B. The cores 214A, 214B are connected in the coupling 258, forming a strong electrical and mechanical connection between the cores. The end face of the casing 254A of small diameter is connected (for example, by welding) with the shell 218A of the insulated conductor 212A. The sleeve 252 and the casing 254B are brought closer (moved or pushed) to the casing 254A, forming a fitting 250. The internal volume of the fitting 250 can essentially be filled with electrical insulating material at the moment of approaching the sleeve and the casings. The total internal volume of the sleeve and the casings is reduced so that the insulating material, essentially completely filling the entire internal volume, is compressed. The sleeve 252 is connected to the casing 254B, and the casing 254B is connected to the shell 218 V of the insulated conductor 212B. If necessary, further pressing the volume of the sleeve 252 can be further reduced.

In some embodiments, the internal volumes of the casings 254A, 254B filled with electrical insulating material 256 are conical in shape. The diameters of the internal volumes of the casings 254A, 254B can cone from a smaller diameter, near or near the ends of the casings connected to insulated conductors 212A, 212B, to a larger diameter, near or near the ends of the casings located inside the sleeve 252 (the ends of the casings are turned to each other friend, or the ends of the casing facing the ends of the insulated conductors). The conical shapes of the internal volume can reduce the intensity of the electric field in the fitting 250. A decrease in the intensity of the electric field in the fitting 250 can reduce leakage currents in the fitting at elevated operating voltages and temperatures, as well as increase the reserve stock before electrical breakdown. So reducing the intensity of the electric field in fitting 250 allows you to increase the range of operating voltages and temperatures at the fitting.

In certain embodiments, the insulation of the insulated conductors 212A, 212B converges to a cone from the sheaths 218A, 218B to the cores 214A, 214B in the direction of the center of the fitting 250 if the insulating material 256 is a weaker dielectric than the insulation in insulated conductors. In certain embodiments, the insulation of the insulated conductors 212A, 212B converges to a cone from the shells 218A, 218B to the cores 214A, 214B in the direction of the insulated conductors if the insulating material 256 is a stronger dielectric than insulation in insulated conductors. The taper of insulation in insulated conductors reduces the intensity of the electric field at the boundary between the insulation of insulated conductors and the insulating material inside the fitting.

Figure 6 shows a tool that can be used to cut sections of the internal parts of insulated conductors 212A, 212B (for example, electrical insulation inside the shell of an insulated conductor). The cutting tool 260 may include cutting teeth 262 and a drive tube 264. The drive tube may be connected to the housing of the cutting tool 260, for example, by welding or soldering. In some embodiments, a cutting tool is not required to cut off the electrical insulation from the interior of the sheath.

The sleeve 252 and the housings 254A, 254B can be interconnected by any means known from the prior art, such as soldering, welding or crimping. In certain embodiments, as shown in FIG. 7, there is a thread on the sleeve 252 and on the housings 254A, 254B that engages to connect the parts together.

As shown in FIGS. 5 and 7, in some embodiments, the insulating material 256 is compressed during the installation process. The force for pressing the housings 254A, 254B in the direction of each other can apply pressure to the insulating material 256, for example, at least from 172.4 MPa to 379.2 MPa to ensure sufficient compression of the insulating material. The conical shape of the internal volumes of the casings 254A, 254V and the layout of the insulating material 256 can enhance the compression of the insulating material during the installation process to such an extent that the dielectric characteristics of the insulating material are, as far as possible, comparable with the dielectric characteristics inside the insulated conductors 212A, 212B. Methods and devices for simplifying compression include, but are not limited to, mechanical methods (as shown in FIG. 10), pneumatic, hydraulic (as shown in FIGS. 11 and 12), stamping, or a combination thereof.

Moving the parts to each other with force and the conical shape of the inner volume of the shells allow compressing the insulating material 256 in both axial and radial directions. Axial and radial compression of the insulating material 256 provides a more uniform pressing of the insulating material. In certain embodiments, vibration and / or compaction of the insulating material 256 may also be used to seal the insulating material. Vibration (and / or ramming) can be used simultaneously with the application of force to bring the housings 254A, 254B closer together, or vibration (and / or ramming) ) may alternate with the application of such an effort. Vibration and / or ramming can reduce the distance between particles of insulating material 256.

In the embodiment shown in FIG. 7, the insulating material 256 inside the housings 254A, 254B is mechanically compressed by tightening the nuts 266 to the crimp rings 268 connected to the sheaths 218A, 218B. The mechanical method allows to compress the internal volumes of the casings 254A, 254B due to the conical shape of the internal volume. Crimp rings 268 may be copper or made of another soft metal. Nuts 266 may be stainless steel nuts or nuts of another hard metal capable of moving through shells 218A, 218B. Nuts 266 may engage with threads on housings 254A, 254B to interface with housings. As the nuts 266 are threaded on the housings 254A, 254B, the nuts 266 and compression rings 268 compress the internal volume of the housings. In certain embodiments, nuts 266 and crimp rings 268 can be used to move housings 254A, 254V through sleeve 252 (due to a threaded connection between parts) and compress the internal volume of the sleeve.

In certain embodiments, the housings 254A, 254B and the sleeve 252 are connected to each other by a threaded connection before the nut and crimp ring are lowered down to the second part. As the internal volume is compressed inside the housings 254A, 254B, the internal volume inside the sleeve 252 can also be compressed. In certain embodiments, nuts 266 and crimp rings 268 can be used to connect enclosures 254A, 254B to insulated conductors 212A, 212B.

In some embodiments, several insulated conductors are spliced together in an end fitting. For example, three insulated conductors can be spliced together in an end fitting to electrically connect insulated conductors into a 3-phase star configuration. On figa shows a side view in cross section of one embodiment of a threaded fitting 270 for connecting three insulated conductors 212A, 212B, 212C. On Fig shows a side view in cross section of one embodiment of a welded fitting 270 for connecting three insulated conductors 212A, 212B, 212C. As shown in FIGS. 8A and 8B, insulated conductors 212A, 212B, 212C may be connected to fitting 270 via end cap 272. End cap 272 may include three strain relief fittings 274 through which insulated conductors 212A, 212B pass, 212C.

The insulated conductor cores 214A, 214B, 214C may be connected in a sleeve 258. The sleeve 258 may be, for example, a solder point (eg, silver or copper brazing), a weld or crimp. The connection of the cores 214A, 214B, 214C in the coupling 258 allows three insulated conductors to be electrically connected for use in a 3-phase star configuration.

As shown in FIG. 8A, the end cap 272 may be connected to the main body 276 of the fitting 270 by thread. The threaded connection of the end cap 272 and the main body 276 allows the end cap to compress the insulating material 256 inside the main body. At the end of the main body 276, opposite the end cap 272, there is a cover 278. The cover 278 can also be attached to the main body 276 by thread. In some embodiments, the compression of the insulating material 256 in the fitting 270 is enhanced by tightening the cover 278 to the main body 276, by crimping the main body after attaching the cover, or by a combination of these methods.

As shown in FIG. 8B, the end cap 272 may be connected to the main body 276 of the fitting 270 by welding, soldering, or crimping. The end cap 272 can be pushed or pressed into the main body 276 to compress the insulating material 256 inside the main body. Cover 278 can also be attached to main body 276 by welding, soldering, or crimping. The cover 278 may be pushed or pressed into the main body 276 to compress the insulating material 256 inside the main body. Compression of the main body after attaching the cover may further enhance the compression of the insulating material 256 in the fitting 270.

In the individual embodiments shown in FIGS. 8A and 8B, the openings or openings in the cover 278 are closed with plugs 280. For example, the plugs may be threaded, welded or soldered to the hole in the cover 278. The holes in the cover 278 allow the insulating material 256 to be placed inside the fitting 270 after the cover 278 and the end cover 272 are connected to the main body 276. The holes in the cover 278 can be plugged or closed after the insulating material 256 is placed inside the fitting 270. In some embodiments, the openings located in the main body 276 of the fitting 270. The holes in the main body 276 can be closed with plugs 280 or other plugs.

In certain embodiments, cap 278 includes one or more studs. In individual embodiments, the studs are studs or part of plugs 280. The studs can engage with a torque tool that rotates and tightens the cover 278 on the main body 276. An example of a torque tool 282 that can mesh with the studs is shown in FIG. 9. The torque tool 282 may have an inner diameter that substantially corresponds to the outer diameter of the cap 278 (as shown in FIG. 8A). As shown in FIG. 9, the torque tool 282 may have grooves or other recesses, the shape of which allows them to engage with studs on the cover 278. The moment tool 282 may include a recess 284. The recess 284 may be a square drive recess or another form of recess allowing you to use (rotate) the torque tool.

Figure 10 shows one embodiment of the clamping devices 286A, B that can be used to mechanically compress the fitting 250. The clamping devices 286A, B can be shaped to fit the fitting 250 in place on the shoulders of the housings 254A, 254B. The threaded rods 288 can pass through the holes 290 of the clamping devices 286A, B. Nuts 292 with gaskets on each of the threaded rods 288 can be used to jointly apply forces to the external surfaces of each clamping device so that compressive forces are applied to the casings 254A, 254B of the fitting 250. Such compressive forces compress the electrical insulation material within the fitting 250.

In certain embodiments, clamping devices 286 are used in hydraulic, pneumatic, or other compression methods. FIG. 11 shows an exploded view of one embodiment of a hydraulic press 294. FIG. 12 shows one embodiment of an assembled hydraulic press 294. As shown in FIGS. 11 and 12, clamping devices 286 may be used to secure fitting 250 ( for example, in FIG. 5) in situ, together with insulated conductors coupled to the fitting. At least one assembled clamping device (e.g., clamping device 286A) may be movable to compress the fitting axially. The power supply device 296 of FIG. 11 can be used to power the press 294.

13 depicts one embodiment of a fitting 250 and insulated conductors 212A, 212B secured to a clamping device 286A and clamping device 286 B before pressing the fitting and insulated conductors. As shown in FIG. 13, the cores of insulated conductors 212A, 212B are connected in a sleeve 258 near or adjacent to the center of the sleeve 252. The sleeve 252 slides along the housing 254A that is connected to the insulated conductor 212A. The sleeve 252 and the casing 254A are fixed in a fixed (fixed) clamping device 286 V. The insulated conductor 212B passes through the casing 254B and the movable clamping device 286A. Insulated conductor 212B may be secured with another clamping device fixed relative to clamping device 286B (not shown). The clamping device 286A can be moved toward the clamping device 286 V to connect the housing 254B to the sleeve 252 and to compress the insulating material inside the housing and the sleeve. The joints between the insulated conductor 212A and the casing 254A, between the casing 254A and the sleeve 252, between the bushing 252 and the casing 254B, and also between the casing 254B and the insulated conductor 212B can be connected by welding, soldering or other methods known from the prior art.

FIG. 14 is a side view of one embodiment of a fitting 298 for connecting insulated conductors. The fitting 298 may be a cylinder or a sleeve having a sufficient clearance between the inner diameter of the sleeve and the outer diameters of the insulated conductors 212A, 212B so that the sleeve can be worn on the ends of the insulated conductors. The cores of insulated conductors 212A, 212B can be connected inside the fitting 298. The shells and insulation of insulated conductors 212A, 212B can be cut or stripped to expose the cores to a sufficient length before connecting the cores. The fitting 298 may be centered between the end portions of the insulated conductors 212A, 212B.

Fitting 298 can be used to connect the insulated conductor 212A to the insulated conductor 212B while maintaining the mechanical and electrical integrity of the shells, insulation, and cores of insulated conductors. Fitting 298 can be used to connect heat-insulated conductors to non-heat-insulated conductors, to connect heat-insulated conductors to other heat-insulated conductors, or to connect non-heat-insulated conductors to other non-heat-insulated conductors. In certain embodiments, more than one fitting 298 is used to couple multiple heat generating and non heat generating insulated conductors and produce a long insulated conductor.

Fitting 298 can be used to connect insulated conductors of different diameters. For example, insulated conductors may have cores of different diameters, shells of different diameters, or a combination of elements of different diameters. Fitting 298 can also be used to connect insulated conductors with different metallurgical compositions, different types of insulation, or a combination of these properties.

In some embodiments, fitting 298 has at least one angled bevel end. For example, the ends of fitting 298 may be chamfered at an angle relative to the longitudinal axis of the fitting. The angle, for example, can be about 45 ° or range from 30 ° to 60 °. Thus, the ends of fitting 298 can have a substantially elliptical cross section. The substantially elliptical cross-section of the ends of the fitting 298 provides an increased area for welding or soldering the fitting with insulated conductors 212A, 212B. The increased connection area increases the strength of the spliced insulated conductors. In the embodiment of FIG. 14, the oblique ends of the fitting 298 give the fitting a substantially parallelogram shape.

The angled ends of fitting 298 provide the fitting with an increased tensile strength and increased flexural strength compared to a fitting with straight ends due to load distribution along the fitting. The fitting 298 can be oriented so that when the insulated conductors 212A, 212B and the fitting are wound (for example, on a coiled tubing installation), the angled beveled ends act as the point of transfer of stiffness from the fitting body to insulated conductors. Such a transition point reduces the likelihood that the insulated conductors will bend or clamp at the ends of the fitting body.

As shown in FIG. 14, there is a hole 300 in fitting 298. Hole 300 allows electrical insulating material (eg, insulating material 256 of FIG. 5) to be placed (filled) inside fitting 298. Hole 300 may be a groove or other longitudinal hole extending along part of the length of the fitting 298. In some embodiments, the hole 300 extends essentially over the entire gap between the ends of the insulated conductors 212A, 212B within the fitting 298. The hole 300 allows you to fill essentially the entire volume (area) between the insulated conductors 212A, 212B, as well as around any welded or spliced joints between insulated conductors by electrical insulating material, without the need for axial movement of the insulating material in the direction of the ends of the volume between the insulated conductors. The width of the hole 300 allows you to force the insulating material through the hole and pack it more tightly inside the fitting 298, thereby reducing the amount of empty space inside the fitting. The insulating material can be forcedly pumped through the groove into the volume between the insulated conductors 212A, 212B, for example, using a tool the size of the groove. The tool can be forced into the groove for pressing the insulating material. Then additional insulating material may be added and re-pressed. In certain embodiments, the insulating material may be further compressed inside fitting 298 by vibration, ramming, or other methods. In addition, the compression of the insulating material allows a more even distribution of the insulating material within the fitting 298.

After filling the fitting with electrical insulating material 298, and in some embodiments of compressing the electrical insulating material, the opening 300 may be closed. For example, an insert or other overlap may be placed in the hole and secured in place. On Fig shows a side view of one embodiment of the fitting 298 with the hole 300 closed insert 302. The insert 302 can be welded or soldered to the fitting 298 to close the hole 300. In some embodiments, the insert 302 is ground or polished so that the insert was flush with the surface of fitting 298. FIG. 15 also shows that welded or soldered seams 304 may be used to secure fitting 298 to insulated conductors 212A, 212B.

After closing the opening 300, fitting 298 can be pressed mechanically, hydraulically, pneumatically, or using stamping methods to further compress the electrical insulating material within the fitting. Additional compression of the insulating material reduces the volume of the cavities inside the fitting 298, and also reduces leakage currents through the fitting and increases the working range of the fitting (for example, the maximum operating voltage and operating temperature of the fitting).

In some embodiments, fitting 298 includes certain features that further reduce the intensity of the electric field within the fitting. For example, a fitting 298 or a core coupling 258 of insulated conductors inside the fitting may include beveled edges, rounded edges, or other smoothed elements to reduce the intensity of the electric field. On Fig depicts an embodiment of the fitting 298 with signs that reduce the intensity of the electric field in the coupling 258 of the connection of insulated conductors 212A, 212B. As shown in FIG. 16, the coupling sleeve 258 is a welded joint with a smooth or rounded profile to reduce the intensity of the electric field inside the fitting 298. In addition, the fitting 298 has a beveled internal volume to increase the volume of electrical insulating material inside the fitting. The beveled and increased volume reduces the electric field intensity inside fitting 298.

In certain embodiments, attenuators of the electric field voltage may be located within the fitting 298 to reduce the electric field intensity. On Fig shows one of the embodiments of the attenuator 306 voltage of the electric field. The attenuator 306 may be located in the internal volume of the fitting 298 (as shown in FIG. 16). The attenuator 306 may be a detachable ring or other detachable part, so that the attenuator can be installed around the cores 214A, 214B of the insulated conductors 212A, 212B after they are connected (see FIG. 16).

FIGS. 18 and 19 are a sectional view of another embodiment of a fitting 250 used to connect insulated conductors. FIG. 18 is a sectional view of a fitting 250 at a time when insulated conductors 212A, 212B enter the fitting. 19 is a sectional view of fitting 250 with conductors 212A, 212B connected within the fitting. In some embodiments, fitting 250 includes a sleeve 252 and a sleeve 258.

The fitting 250 can be used to connect (spliced) the insulated conductor 212A with the insulated conductor 212 V while maintaining the mechanical and electrical integrity of the shells (braids), insulation and cores (conductors) of the insulated conductors. Fitting 250 may be used to connect heat-insulating conductors to non-heat-insulating conductors, to connect heat-insulating conductors to other heat-insulating conductors, or to connect heat-insulating conductors to other non-heat-insulating conductors. In certain embodiments, more than one fitting 250 is used to couple multiple heat generating and non heat generating insulated conductors and produce a long insulated conductor.

Fitting 250 can be used to connect insulated conductors of different diameters. For example, insulated conductors may have cores (conductors) of different diameters, shells (braids) of different diameters, or a combination of elements of different diameters. The fitting 250 can also be used to connect insulated conductors with different metallurgical composition, with different types of insulation or a combination of these properties.

The sleeve 258 is used to connect and electrically bond the cores 214A, 214B of the insulated conductors 212A, 212B within the fitting 250. The sleeve 258 may be made of copper or another suitable electrical conductor. In some embodiments, the cores 214A, 214B are pressed in or pushed into the sleeve 258. In some embodiments, the sleeve 258 is heated so that the cores 214A, 214B can slide into the sleeve. In certain embodiments, core material 214A is different from core material 214B. For example, core 214A may be copper, while core 214B may be stainless steel, carbon steel, or alloy 180. In such embodiments, special welding methods may be used to connect the cores to each other. For example, the tensile strength and / or yield strength of the cores should be as close as possible so that the joint between the cores does not break down over time or as it is used.

In certain embodiments, the sleeve 258 includes one or more grooves within the sleeve. Grooves may prevent particles from entering or leaving the coupling after connecting the cores in the coupling. In certain embodiments, the sleeve 258 has a tapered inner diameter (for example, a narrower inner diameter toward the center of the sleeve). The taper inner diameter can improve a tight fit between the sleeve 258 and the cores 214A, 214B.

In some embodiments, the insulating material 256 is located inside the sleeve 252. In some embodiments, the insulating material 256 is magnesium oxide or a mixture of magnesium oxide and boron nitrite (80 weight percent magnesium oxide and 20 weight percent boron nitrite). Electrical insulation material 256 may include magnesium oxide, talc, powders of ceramic materials (e.g., boron nitride), a mixture of magnesium oxide and other electrical insulators (e.g., up to 50 weight percent boron nitride), ceramic cement, mixtures of powders of ceramic materials with separate non-ceramic materials (such as tungsten sulfide (WS2)), or mixtures thereof. For example, magnesium oxide can be mixed with boron nitride or another electrical insulator to improve the fluidity of the electrical insulation material, improve the dielectric characteristics of the electrical insulation material, or increase the flexibility of the fitting. In certain embodiments, the insulating material 256 is a material similar to the electrical insulation used inside at least one of the insulated conductors 212A, 212B. The insulating material 256 may have substantially the same dielectric characteristics as the electrical insulation used inside at least one of the insulated conductors 212A, 212B.

In some embodiments, the internal volume of the sleeve 252 is substantially filled with insulating material 256. In some embodiments, the term “substantially filled” refers to a volume or volumes of completely or almost completely filled insulating material, essentially without macroscopic voids in the volume or volumes . For example, a term that is substantially filled may refer to filling almost the entire volume with an insulating material having a certain porosity due to microscopic voids (e.g., porosity up to 40%).

In certain embodiments, the sleeve 252 has one or more grooves 308. The grooves 308 may prevent the insulating material 256 from exiting the sleeve 252 (for example, the grooves trap the insulating material in the sleeve).

In some embodiments, the insulating material 256 has concave end portions near or adjacent to the edges of the sleeve 258, as shown in FIG. The concave shape of the insulating material 256 allows you to strengthen the connection with the insulators 216A, 216B of insulated conductors 212A, 212B. In some embodiments, to improve the connection with the insulating material 256, the electrical insulators 216A, 216B have end sections of a curved (or conical) shape. The end portions of the insulating material 256 and the insulators 216A, 216B may be mixed or mixed under pressure applied during the connection of insulated conductors. Stirring or mixing insulating materials can enhance the connection between insulated conductors.

In some embodiments, insulated conductors 212A, 212B are connected by fitting 250 by jointly moving (pushing) insulated conductors toward the center of the fitting. When moving the insulated conductors 212A, 212B, the cores 214A, 214B jointly move inside the junction 258. After the insulated conductors 212A, 212B are moved together to the fitting 250, the fitting and the terminal sections of the insulated conductors inside the fitting can be sealed or pressed to fix the insulated conductors in the fitting and compress the insulating material 256. Clamping devices can be used to bring the insulated conductors 212A, 212B and the fitting 250 closer together. or other similar devices. In some embodiments, to provide acceptable compression of the insulating material, the compression force of the insulating material 256 is, for example, at least 172.4 MPa to 379.2 MPa. The compression of the insulating material 256 during the installation process allows to obtain the dielectric characteristics of the insulating material, which, as far as practicable, are comparable with the dielectric characteristics inside the insulated conductors 212A, 212B. Methods and devices for enhancing compression include, but are not limited to, mechanical, pneumatic, hydraulic, crimping methods, or a combination of them.

In certain embodiments, the end portions of the sleeve 252 are connected (by welding or soldering) to the sheaths 218A, 218B of the insulated conductors 212A, 212B. In certain embodiments, to increase the strength of the fitting, a support sleeve and / or strain relief device is placed over the fitting 250.

FIGS. 20 and 21 are a cross-sectional view of yet another embodiment of a fitting 250 used to connect insulated conductors. FIG. 20 is a sectional view of a fitting 250 at a time when insulated conductors 212A, 212B enter the fitting. On Fig shows a view in cross section of the fitting 250 with conductors 212A, 212B connected inside the fitting in the final position. An embodiment of fitting 250 of FIGS. 20 and 21 may be similar to an embodiment of fitting 250 of FIGS. 18 and 19.

In some embodiments, the fitting 250 of FIGS. 20 and 21 includes a sleeve 252 and a sleeve 258. A sleeve 258 is used to connect and electrically couple the cores 214A, 214B of the insulated conductors 212A, 212B within the fitting 250. The sleeve 258 may be made of copper or other suitable electrical conductor. In certain embodiments, sleeve 258 is used to connect cores of different diameters. Therefore, the coupling 258 may have halves with different inner diameters corresponding to the diameters of the cores.

In some embodiments, the cores 214A, 214B are pressed into or pressed into the sleeve 258 while pushing the insulated conductors 212A, 212B into the sleeve 252. In some embodiments, the sleeve 258 has a tapered inner diameter (for example, a narrower inner diameter at the center of the junction), such as this is shown in FIG. The conical inner diameter allows for a tighter fit between the sleeve 258 and the cores 214A, 214B and increases the length of the interface between the cores and the sleeve. The increase in the length of the interface between the coupling 258 and the cores 214A, 214B reduces the resistance between the cores and the coupling and prevents an arcing breakdown when applying electric power to the insulated conductors 212A, 212B.

In some embodiments, cores 214A, 214B are pushed together to the final position shown in FIG. 21 so that a gap 309 remains between the ends of the cores. The gap 309 is the gap or space between the ends of the cores 214A, 214B. In certain embodiments, the span 309 is from about 25.4 microns to about 381 microns, or from about 50.8 microns to about 127 microns.

Due to the presence of a gap 309 between the ends of the cores 214A, 214B, the movement of the insulated conductors 212A, 212B when pushing the insulated conductors into the sleeve 252 is limited by pressing the insulators 216A, 216B to the insulating material 256, and not by the junction between the ends of the cores. Therefore, the presence of a gap 309 between the ends of the cores 214A, 214B provides better (stronger) compression of the insulating material 256 and the electrical insulators 216A, 216B inside the sleeve 252 in the final position shown in Fig.21. The increased compression of the insulating material 256 and electrical insulators 216A, 216 V allows you to get a more reliable fitting 250 with improved electrical characteristics.

In addition, the presence of a gap 309 between the ends of the cores 214A, 214B prevents the cores from being pushed toward each other and bending or other deformation of the cores. Joint pushing of the cores 214A, 214B into the sleeve 258 allows the cores to be connected without welding, heating, or otherwise increasing the temperature of the cores. Maintaining a low temperature of the cores 214A, 214B during the connection of the cores prevents softening or fluidity of the material (copper). The preservation of the hardness of the cores 214A, 214B allows to improve the electrical parameters of the fitting 250.

In some embodiments, the end portions of the insulating material 256 are concave near or near the edges of the sleeve 258, as shown in FIG. The concave end portions may have angled edges that form an angle of the enclosing type, as shown in FIG. The concave end portions of the insulating material 256 can increase the strength of the connection with the insulators 216A, 216B of the insulated conductors 212A, 212B. In certain embodiments, to increase the strength of the connection with the insulating material 256, the electrical insulators 216A, 216B have end sections of a curved shape (or angled edges of the male type). Pressing the end sections of a certain shape to each other allows you to straighten the edges of the end sections and eliminate gaps between the end sections. The use of the end sections of the insulating material 256 and the insulators 216A, 216B of a certain shape can improve the compression and / or reduce the distance between the insulating material and the insulators at the pressure created during the connection of insulated conductors 212A, 212B. Compressing insulating material improves the electrical insulating properties of fitting 250.

In some embodiments, the insulated conductors 212A, 212B are moved a predetermined distance into the fitting 250 to provide the necessary compression of the insulating material in the fitting and the necessary connection between the cores 214A, 214B and the sleeve 258. In some embodiments, the insulated conductors 212A, 212V are moved to a predetermined distance at a certain force to provide the necessary compression and the necessary connection. Hydraulic pressure can be used to create force when pushing insulated conductors 212A, 212B into fitting 250. For example, a hydraulic pressure of about 19.3 MPa to about 20.68 MPa allows each of the insulated conductors 212A, 212B to move into fitting 250 over a distance of 2.2 cm to about 2.5 cm.

On Fig depicts one of the embodiments of the blocks of insulating material located around the cores of the connected insulated conductors. The core 214A of the insulated conductor 212A is connected to the core 214B of the insulated conductor 212B at the coupling 258. The cores 214A, 214B are exposed by removing parts of electrical insulators 216A, 216B and shells 218A, 218B around the cores from the ends of the insulated conductors 212A, 212B.

In certain embodiments, cores 214A, 214B have different diameters. In such embodiments, the coupling 258 may taper from the diameter of the core 214A to the diameter of the core 214B. In some embodiments, the cores 214A, 214B are made of different materials. Clutch 258 allows you to compensate for the use of different materials in the cores. For example, sleeve 258 may include a combination or mixture of materials used in cores.

In some embodiments, one or more blocks of insulating material 256 are placed around the exposed parts of the cores 214A, 214B, as shown in FIG. Blocks of insulating material 256 can be made, for example, of magnesium oxide or a mixture of magnesium oxide and another electrical insulator. Blocks of insulating material 256 may be blocks of hard or soft material, depending on the desired type of compression. The required number of blocks of insulating material 256 can be placed around the exposed parts of the cores 214A, 214B so that the blocks substantially completely surround the exposed parts of the cores. The number of blocks of electrical insulating material 256 may vary, for example, depending on the length and / or diameter of the exposed parts of the conductor and / or the size of the blocks of electrical insulating material. In some embodiments, four blocks of electrical insulating material 256 are used to surround the exposed parts of the cores.

On Fig shows two blocks 256A, 256B of insulating material surrounding one half (semicircle) of the exposed parts of the cores 214A, 214B. The depicted blocks of electrical insulating material 256 are semicircular blocks that are tightly mounted around the outer diameter of the exposed parts of the cores. In the embodiment of FIG. 22, two additional blocks of insulating material 256 are placed on the bare parts, surrounding the bare parts of the core with the insulating material. On Fig depicted one of the embodiments with four blocks 256A, 256V, 256C, 256D of electrical insulation material located around the cores of the connected insulated conductors 212A, 212B.

In some embodiments, the blocks of electrical insulating material 256 have an inner diameter of such a size and / or shape that it matches the outer diameter of the exposed parts of the cores 214A, 214B. Correspondence of the inner diameter of the blocks to the outer diameter of the exposed core parts allows a tight fit of the blocks and exposed core parts and to prevent or reduce the formation of gaps during the compression of the blocks.

In certain embodiments, one or more blocks of electrical insulating material 256 have a tapered inner diameter corresponding to a tapered outer diameter of the sleeve 258 and / or exposed parts of the cores 214A, 214B, as shown in FIG. 22. The inner diameter of the blocks of insulating material 256 can be obtained by sandblasting or grinding the inner diameter of the blocks to the desired conical shape.

After placing blocks of electrical insulating material 256 around the exposed parts of the cores (as shown in FIG. 23), a sleeve or other covering element is placed over the connected insulated conductors, essentially covering the blocks and at least a portion of each insulated conductor. On Fig shows one of the embodiments of the inner sleeve 252A, placed on top of the connected insulated conductors 212A, 212B. The inner sleeve 252A may be made of the same or similar material that is used to make the shells 218A, 218B of insulated conductors 212A, 212B. For example, the inner sleeve 252A and shells 218A, 218B may be made of stainless steel 304. The inner sleeve 252A and shells 218A, 218B are usually made of materials that can be joined together by welding.

The inner sleeve 252A fits tightly or tightly over the shells 218A, 218B of insulated conductors 212A, 212B. In certain embodiments, axial and / or radial grooves are provided on the outer surface of the inner sleeve 252A. In some embodiments, an alignment ridge 310 is provided on the inner sleeve 252A. The alignment ridge 310 is located near or adjacent to the center of the coupling sleeve of insulated conductors 212A, 212B.

After placing an inner sleeve around the blocks of electrically conductive material (as shown in FIG. 24), an outer sleeve or other cylindrical covering element is placed on top of the inner sleeve. On Fig depicts one of the embodiments of the outer sleeve 252B, placed on top of the inner sleeve 252A and connected insulated conductors 212A, 212B. In some embodiments, the outer sleeve 252B is shorter than the inner sleeve 252A. In some embodiments, an opening 312 is provided in the outer sleeve 252B. A hole 312 may be located near or near the center of the outer sleeve 252B. The hole 312 can be aligned with the alignment ridge 310 on the inner sleeve 252A (the alignment ridge is visible through the hole). In certain embodiments, the outer sleeve 252B consists of two or more parts. For example, the outer sleeve may consist of two parts interconnected in the form of a shell. Parts may be welded or otherwise connected to form an outer sleeve. In certain embodiments, there are axial and / or radial grooves on the inner surface of the outer sleeve 252B.

The outer sleeve 252B may be made of the same or similar material that is used to make the inner sleeve 252A and shells 218A, 218B (for example, stainless steel 304). The 252V outer sleeve may fit tightly or tightly onto the inner sleeve 252A. After the outer sleeve 252B and the inner sleeve 252A are placed on the shells 218A, 218B of the insulated conductors 212A, 212B, the bushings can be permanently connected (for example, welded) to the shells 218A, 218B. The bushings 252A, 252B can be permanently connected to the shells 218A, 218B so that the ends of the bushings are substantially sealed (so that there are no leaks at the ends of the bushings through which air or other fluids can escape or enter the ends of the bushings). After connecting the sleeves 252A, 252B to the shells 218A, 218B, the hole 312 is the only aperture for the fluid to exit / enter the outer sleeve 252B and the inner sleeve 252A substantially sealed thereto.

In some embodiments, a fluid (eg, hydraulic fluid) is supplied to the inner volume of the outer sleeve 252B through an opening 312. In some embodiments, the fluid is a hydraulic oil. In certain embodiments, the fluid may be another fluid, such as a molten salt or gas. In certain embodiments, the fluid is heated during crimping.

The fluid supplied to the internal volume of the outer sleeve 252B may be crimped to compress or compress the inner sleeve 252A and the electrical insulating material 256. For example, the fluid may be hydraulically crimped using a hand pump or other appropriate hydraulic pressure pump. The compression of the fluid inside the outer sleeve 252B allows you to create isostatic pressure to compress the inner sleeve 252A.

The external sleeve 252 V may be rigid and not subject to compression by pressure, while the internal sleeve 252A may be subjected to compression by pressure. For example, the inner sleeve 252A may be thinner than the outer sleeve 252B and / or the inner sleeve may be heat treated (annealed) so that it becomes softer than the outer sleeve.

The fluid inside the outer sleeve 252B is crimped to a predetermined pressure or in a predetermined pressure range to compress the inner sleeve 252A and the insulating material 256 to the desired degree of compression. In certain embodiments, the fluid inside the outer sleeve 252B is crimped to a pressure of about 100 MPa to 140 MPa. In certain embodiments, the fluid may be crimped to a higher pressure (eg, crimped to about 240 MPa).

When pressure testing the fluid to this pressure, the inner sleeve 252A deforms due to compression of the inner sleeve and the insulating material 256 is compressed inside the inner sleeve. The inner sleeve 252A may be uniformly deformed by the pressure of the fluid inside the outer sleeve 252B. In some embodiments, the insulating material 256 is compressed so that the insulating material acquires dielectric properties similar and higher than the dielectric properties of the insulator of at least one of the connected insulated conductors. The use of a crimping fluid to compress and compress the inner sleeve 252A and the insulating material 256 allows you to connect the insulated conductors in the bushings in a horizontal position. The connection of insulated conductors in a horizontal position allows you to increase the length of interconnected insulated conductors without the use of complex and expensive cable management systems.

In some embodiments, the ends of the insulated conductors may have bevels or tapers to seal the inner sleeve. FIG. 26 shows one embodiment of the tapered end of an insulated conductor after compression. The insulated conductor 212 has a bevel 314 inside the inner sleeve 252A. The bevel 314 can prevent the bending or bending of the inner sleeve 252A during compression.

In certain embodiments, an insulating powder material is added to the inside of the inner sleeve 252A before sealing and pressing the inner sleeve. The electrical insulating powder material can penetrate and fill the voids inside the inner sleeve (for example, in the recess formed between the bevel of the insulated conductor and the inner sleeve). The use of electrically insulating powder material also reduces the number of interfaces in the pressed electrically insulating material. In certain embodiments, an electrical insulating powder material is used in place of blocks of electrical insulating material.

In certain embodiments, an additive, such as a dopant or other filler material, may be added to the insulating material. The additive allows to improve the dielectric properties of the insulating material. For example, the additive improves the dielectric strength of the insulating material.

In some embodiments, mechanical and / or hydraulic compression (for example, an electrically insulating material in powder form) is used to radially compress an insulating material in a coupling for insulating conductors. On Fig depicts one of the embodiments of the first half 316A of the compression device 316 used to compress the insulating material in the coupling of insulated conductors. The second half of the device 316 has the same shape and size as the first half 316 of FIG. The first half and second half of the device 316 are interconnected, forming a device around a segment of interconnected insulated conductors.

On Fig depicts one embodiment of a device 316 connected around insulated conductors 212A, 212B. For clarity, the parts of the cores inside the device 316, the sheath and the electrical insulator surrounding the cores of the insulated conductors 212A, 212B, are not shown.

As shown in FIG. 27, the first half 316A includes a first half 318A of an opening 318 formed at the top of the device 316 after the two halves of the device are connected together. Hole 318 allows electrical insulating material and / or other materials to be placed in the space around the bare cores of insulated conductors. In some embodiments, powdered electrical insulation material is placed in device 316.

As shown in FIG. 28, after at least a portion of the insulating material is fed through the opening 318 into the device 316 located around the bare conductors, a first plunger 320A is inserted into the opening. The first plunger 320A is used to compress (for example, by applying mechanical and / or hydraulic force to the top of the plunger) an insulating material inside the device 316. For example, force can be applied to the first plunger 320A using a hammer (mechanical pressing) or a hydraulic piston (hydraulic pressing).

On Fig shows a side view of the insulated conductor 212, located inside the device 316, the first plunger 320A is located above the insulated conductor with a bare core 214. In some embodiments, at the bottom of the first plunger 320A there is a recess 322A. The shape of the recess 322A may be substantially similar to the shape of the exposed portion of the core. The first plunger 320A may have a stopper 324, shown in FIG. 28, preventing the first plunger from immersing into the device 316. For example, the stoppers 324 may prevent the first plunger 320A from entering the device 316 beyond a certain depth, after which bending or deformation of the isolated cores may occur. conductors. In certain embodiments, the first plunger 320A is designed to go to a predetermined depth at which the cores of insulated conductors do not bend or deform without using stoppers (for example, the upper plunger plate acts as a stopper).

The first plunger 320A can be used to compress the insulating material 256 inside the device 316 to a first degree. For example, as shown in FIG. 29, the insulating material 256 is compressed to such an extent that it surrounds the lower part (for example, the lower half) of the exposed core 214. The process of adding the insulating material and compressing the material with the first plunger can be repeated until the necessary degree of compression around the core part will not be achieved.

FIG. 30 shows a side view of an insulated conductor 212 located inside the device 316, a second plunger 320B located above the insulated conductor with a bare core 214. In some embodiments, a recess 322 B is provided at the bottom of the second plunger 320B. The shape of the recess 322B may essentially , match the external shape of the insulated conductor.

In some embodiments, the recess 322B in the second plunger 320B has a different shape, or the recess is missing. On figa-D depicts other embodiments of the second plunger 320B. On figa recess in the second plunger 320B is missing. On figv edges of the recess 322B beveled at an angle of 30 °. On figs the straight edges of the recess 322B beveled at an angle of 15 °. In Fig. 31D, the recess 322B is slightly smaller (shorter sides) than the recess in Fig. 30.

A second plunger 320B may be used to compress the insulating material 256 inside the device 316 to a second degree. For example, as shown in FIG. 30, the insulating material 256 is compressed to such an extent that it surrounds the exposed core 214. The process of adding the insulating material and compressing the material with the second plunger can be repeated until the desired degree of compression around the part is achieved. core. For example, the process can be repeated until the necessary degree of compression of the insulating material is achieved so that its shape and outer diameter match the shape and outer diameter of the insulated conductor.

After the required amount of electrical insulating material has been pressed, device 316 can be removed from a position around an insulated conductor coupling. On Fig depicted one of the embodiments in which the second half of the device 316 is removed, and the left first half 316A compresses the insulating material 256 around the coupling of the insulated conductors 212A, 212B.

After removal of the device 316, the compressed electrical insulating material 256 can be given a substantially cylindrical shape, the outer diameter of which relative to the outer diameter of the insulated conductors 212A, 212B, as shown in Fig. 33. The final shape of the compressed electrical insulating material 256 can be made by removing excess pressed material. For example, excess compressed material 256 can be axially removed using a circular saw, dressing a sleeve with a cutting edge on the compressed material, and / or using other techniques known in the art.

After finalizing the insulating material 256, the sleeve 252 can be placed on top of the insulating material as shown in Fig. 34. The sleeve 252 may have two or more parts placed on top of the insulating material and connected (by welding) to each other, forming a sleeve. In certain embodiments, two or more parts of the sleeve 252 are compressed by means of a crimping fluid inside the external sleeve (as described in the embodiments of the internal sleeve 252A and the external sleeve 252B of FIGS. 24 and 25) and / or by mechanical crimping of the parts of the sleeve with a friend (as described in embodiments of sleeve 252 of FIGS. 36 and 37). Compression of the sleeve 252 by means of a crimping fluid and / or mechanical crimping eliminates the gaps between the parts of the sleeve so that welding is not required to connect the parts together. In addition, as a result of compression by means of a compression fluid and / or mechanical crimping, the joints between the sleeve 252 and the insulating material 256 can be destroyed (a denser fixed fit is created). The sleeve 256 can be connected (by welding) with the shells of insulated conductors 212A, 212B. The sleeve 252 may be made of the same material as the sheath of insulated conductors 212A, 212B. For example, sleeve 252 may be made of 304 stainless steel.

In some embodiments, the electrically insulating material 256 compressed in the device 316 is a mixture of powdered magnesium oxide and powdered boron nitride. In one embodiment, the electrically insulating material 256 compressed in device 316 is a mixture of 80 weight percent magnesium oxide powder and 20 weight percent boron nitride powder. Other electrical insulating materials and / or other mixtures of electrical insulating materials may also be used. In certain embodiments, a combination of powder electrical insulation material and blocks of electrical insulation material is used.

On Fig depicts one embodiment of a hydraulic press 426, which can be used to apply force to the plunger for hydraulic pressing of the insulating material inside the device (for example, the device 316 of Fig.27-32). The hydraulic press 426 may include a piston 428 and a device holder 430. In some embodiments, insulated conductors can be fed through clamps 432 of hydraulic press 426 so that end portions of insulated conductors are located below piston 428 and above device holder 430. Clips 432 can be used to secure the ends of insulated conductors in press 426. Positioners 434 can be used to adjust the position of insulated conductors.

A device, such as the device 316 of FIGS. 27-32, can be placed around the ends of insulated conductors at the device holder 430 (for example, two halves of the device are connected around the ends of insulated conductors). The device holder 430 may support the device while compressing material in the device. During compression, the piston 428 can exert force on the plunger (for example, the first plunger 320A of FIGS. 28-29 and / or the second plunger 320B of FIG. 30) to compress the insulating material around the ends of the insulating material. In some embodiments, the piston 428 generates a force of up to about 50 tons.

Hydraulic pressing of the insulating material in the device 316 of FIGS. 27-32 can provide a degree of compression (for example, compression of up to about 85%) of the insulating material, similar to the degree of compression of insulated conductors. Similar degrees of compaction make it possible to obtain splices capable of withstanding temperatures of approximately 700 ° C. Hydraulic pressing of the insulating material in the device 316 allows for more controlled compression and / or more reproducible compression (reproducible from splic to splic). Hydraulic pressing can be carried out with less movement or change, creating a more uniform and constant pressure than with mechanical pressing.

In certain embodiments, hydraulic compression is used in combination with mechanical compression (for example, an electrical insulating material is first compressed mechanically and then compressed using hydraulic compression). In certain embodiments, the insulating material is compressed at elevated temperature. For example, the insulating material may be compressed at a temperature of about 90 ° C or higher. In certain embodiments, the first plunger 320A and / or the second plunger 320B are coated with non-stick material. For example, the plungers can be coated with a non-metallic material, such as ceramic coating or DLC (diamond-like carbon), offered by Morgan Technical Ceramics (Berkshire, England). Coating the plungers prevents metal from entering the insulating material and / or sticking the insulating material to the plungers.

In certain embodiments, the sleeve is mechanically compressed in a circle around the sleeve to compress the sleeve. On Fig depicted one of the embodiments of the sleeve 252 used in mechanical compression around the circumference. A sleeve 252 may be placed around the blocks and / or powder insulating material. For example, a sleeve 252 may be placed around the blocks of the electrical insulation material of FIG. 23, the compressed powder electrical insulation material of FIG. 33, or a combination of the illustrated blocks and the powder material.

In some embodiments, the sleeve 252 includes ribs 326. The ribs 326 may be raised portions of the sleeve 252 (e.g., high points on the outside diameter of the sleeve). The shape and size of the ribs 326 may correspond to the crimp portions of the press used to mechanically compress the sleeve 252. For example, the sleeve 252 can be compressed using a hydraulic mechanical compression system that circumferentially compresses the sleeve. For example, sleeve 252 can be compressed using a Pyplok® crimping tool from Mae® Industries (Stony Creek, Ontario, Canada).

The compressing parts of the press compress the ribs 326 until the ribs are almost pressed against the outer diameter of the remaining parts of the sleeve 252 (the diameter of the ribs is essentially the same as the diameter of the rest of the sleeve). On Fig shows one of the embodiments of the sleeve 252 on insulated conductors 212A, 212B after the sleeve and ribs 326 have been circumferentially compressed. When the ribs 326 are compressed around the circumference (radially), the insulating material inside the sleeve 252 is compressed and connects the sleeve with insulated conductors 212A, 212B. The sleeve 252 may be further connected to insulated conductors 212A, 212B. For example, the ends of the sleeve 252 can be welded to the shells of insulated conductors 212A, 212B.

The fittings shown here (including, but not limited to, fitting 250 (in FIGS. 5, 7, 18, 19, 20 and 21), fitting 270 (in FIG. 8), fitting 298 (in FIGS. 14, 15 and 16) , embodiments of a fitting consisting of an inner sleeve 252A and an outer sleeve 252B (in FIGS. 22-25), as well as embodiments of a sleeve 252 (in FIGS. 34, 36 and 37) can form durable electrical and mechanical connections between insulated conductors. For example, the fittings shown here are suitable for continuous operation at voltages above 1000 V, above 1500 V or above 2000 V and at a temperature of less than at least above 650 ° C, at least above 700 ° C, at least above 800 ° C.

In some embodiments, the fittings shown here connect insulated conductors used for heating (e.g., insulated conductors located in a hydrocarbon-containing layer) with insulated conductors not used for heating (e.g., insulated conductors used on the overlying portions of the formation). The core of a heating insulated conductor may be smaller than that of a non-heating insulated conductor and made of another core material. For example, the core of a heating insulated conductor can be made of a copper-nickel alloy, stainless steel or carbon, then the core of a non-heating insulated conductor can be made of copper. However, due to the difference in the sizes and electrical properties of the core materials, the thickness of the electrical insulation in different areas can vary quite a lot and such a difference cannot be compensated for by a single fitting connecting the insulated conductors. Therefore, in some embodiments, between the heating insulated conductor and the non-heating insulated conductor, a short portion of the intermediate heating insulated conductor can be used.

The core diameter of the intermediate insulated heating conductor may cone from the core diameter of the non-heating insulated conductor to the diameter of the core of the heating conductor if its core material is similar to the core material of the non-heating insulated conductor. For example, an intermediate heating insulated conductor may be made of copper, and the diameter of its core may cone to the same diameter as that of a heating insulated conductor. Therefore, the thickness of the electrical insulation of the fitting connecting the intermediate insulated conductor and the heating insulated conductor is the same as the thickness of the electrical insulation of the heated insulated conductor. The same thickness makes it easy to connect insulated conductors in the fitting. The intermediate heating insulated conductor creates some voltage drop and some heat loss due to the smaller core diameter, however, since the intermediate heating insulated conductor can be relatively small in length, such losses will be minimal.

In some embodiments, a fitting for connecting insulated conductors is compressed or compressed to improve the electrical insulation properties (dielectric characteristics) of the electrical insulation material within the fitting. For example, the compression of the insulating material inside the fitting can improve the uniformity of the insulating material and / or eliminate voids or other joints in the insulating material.

In certain embodiments, blocks of electrical insulating material (e.g., magnesium oxide) are compressed in a fitting. In certain embodiments, powder electrical insulation material is compressed in the fitting. In certain embodiments, combinations of powder material and / or blocks of electrical insulating material are used in the fitting. In addition, combinations of different types of electrical insulating material can be used (for example, a combination of magnesium oxide and boron nitride).

In embodiments contemplated herein that use powder electrical insulating material, the powder material has certain compression improving properties (high compression density). In certain embodiments, the powder material has a predetermined particle size distribution (for example, for powdered magnesium oxide, the particle size distribution may range from about 100 microns to about 200 microns). The desired range can be selected so that the powder material is compressed to the desired density. Other properties of the powder material that can be selected to provide the desired density include, but are not limited to, particle shape, presence of impurities (e.g., content of impurities such as silicon or calcium), frictional properties of walls (angle of friction against walls) , compressibility at standard effort (compression in a standard size cylinder at the same effort) and the angle of the hopper to ensure mass flow in the hopper. A combination of one or more of these properties may indicate the compressibility of the powder material and / or the ability of the powder material to flow during compression or compression.

The fitting used to connect insulated conductors can be pressed mechanically, pneumatically and / or hydraulically. Compression fitting allows to improve the dielectric characteristics of the insulating material in such a way that the insulating material can have dielectric characteristics similar to the dielectric characteristics of electrical insulation in insulated conductors. In certain embodiments, the dielectric material compressed in the fitting may have higher dielectric characteristics than the electrical insulation of insulated conductors.

For example, electrical insulation (magnesium oxide) in an insulated conductor typically has a density of from about 78% to about 82%. Unpressed powdered magnesium oxide may have a density of from about 50% to about 55%. Magnesium oxide blocks can have a density of about 70%. According to some variants of the fitting considered here, the electrical insulation inside the fitting after compression or compression has a density that differs by approximately no more than 15%, approximately no more than 10%, or approximately no more than 5% from the density of insulated conductors connected to the fitting. According to individual versions of the fitting considered here, the electrical insulation inside the fitting after pressing or compression has a higher density than the density of insulated conductors connected to the fitting. For example, electrical insulation inside a fitting can have a density of up to about 85%.

In some embodiments discussed herein, a reinforcing sleeve or other tension-relieving device is placed near or adjacent to an insulated conductor coupling. On Fig shows one of the embodiments of the amplification bushings 328 on connected insulated conductors 212A, 212B. Reinforcing sleeves 328 provide strain relief to increase bond strength between insulated conductors. Reinforcing sleeves 328 allow you to reel, unwind and tension connected insulated conductors for installation / extraction in wellbores and / or in the installation channel (for example, a coiled tubing installation).

Fig. 39 shows an exploded view of another embodiment of a fitting 270 used to connect insulated conductors 212A, 212B, 212C. In some embodiments, the fitting 270 includes a strain relief fitting 274, an electric bus 330, a cylinder 332, and an end cap 272. FIGS. 40-47 show one embodiment of a method for mounting the fitting 270 at the ends of insulated conductors 212A, 212B, 212C.

40, insulated conductors 212A, 212B, 212C extend through longitudinal holes in fitting 274 to relieve tension. The strain relief fitting 274 may be terminated for insulated conductors 212A, 212B, 212C. After the insulated conductors 212A, 212B, 212C are placed in the fitting 274 to relieve tension, the insulated conductors 212A, 212B, 212C are aligned in the fitting 274 to relieve tension, and some of the cores 214A, 214B, 214C protruding from the fitting are exposed. Cores 214A, 214B, 214C are exposed by removing the ends of the shells and electrical insulation from insulated conductors 212A, 212B, 212C passing through fitting 274 to relieve tension.

In some embodiments, the end portions of the cores 214A, 214B, 214C passing through the fitting 274 to relieve tension are soldered to the fitting to relieve tension. Examples of soldering materials include, but are not limited to, nickel solders such as AWS 5.8 BNi-2 for low sulfur materials and AWS 5.8 BNi-5A for high sulfur materials. The soldering material may be fluid during soldering, filling and sealing the gaps between the cores 214A, 214B, 214C and fitting 274 to relieve tension. Sealing the gaps does not allow fluid to flow into the fitting 270. Soldering the end portions of the cores 214A, 214B, 214C to the fitting 274 to relieve tension allows the cores to be closer to each other and to reduce the size of the fitting to relieve tension. Reducing the fitting 274 to ease the tension reduces the diameter of the fitting 270 and the wellbore, since it is usually the termination (fitting 270) that is the key factor in determining the size of the wellbore. In certain embodiments, the sheath of insulated conductors 212A, 212B, 212C is connected to fitting 274 to relieve tension. For example, sheaths may be welded (with a continuous lap seam) to fitting 274 to relieve tension.

41, a first cylinder 332A is connected to the end face of the fitting 274 to relieve tension with protruding cores 214A, 214B, 214C. The first cylinder 332A may be welded locally to the end of fitting 274 to relieve tension. The longitudinal length of the first cylinder 332A may be shorter than the protruding cores 214A, 214B, 214C. Therefore, at least a portion of the cores may extend beyond the length of the first cylinder 332A.

After connecting the first cylinder 332A to the fitting 274 to relieve tension, the cylinder is filled with an insulating material that partially covers the cores 214A, 214B, 214C, as shown in Fig. 42. Therefore, at least a portion of the cores protrudes above the electrical insulation material 256. The electrical insulation material 256 may include powder material and / or blocks of electrical insulation material (eg, magnesium oxide). In some embodiments, the insulating material 256 is compressed inside the first cylinder 332A. The insulating material 256 may be compressed hydraulically and / or mechanically using a compression tool. For example, a force can be applied to the compression tool using a piston of a hydraulic press. On Fig depicted one of the embodiments of the compression tool 334A, which can be used to compress the insulating material 256. The compression tool 334A may have holes that allow you to wear the tool on the cores 214A, 214B, 214C when compressing the insulating material. After pressing during the above and subsequent steps, scars may form on the surface of the electrical insulating material. Scars on the surface of the insulating material 256 improve adhesion between the layers of the insulating material during the compaction of the layers.

In some embodiments, after pressing the insulating material 256 in the cylinder 332A, the protruding parts of the cores 214A, 214B, 214C are connected to the busbar 330, as shown in FIG. 43. The busbar 330 may, for example, be made of copper or other material suitable for electrically connecting the cores 214A, 214B, 214C to each other. In certain embodiments, the busbar 330 is welded to the cores 214A, 214B, 214C.

After connecting the busbar 330 to the cores 214A, 214B, 214C, the second cylinder 332B can connect to the first cylinder 332A, forming a cylinder 332 around the protruding parts of the cores, as shown in Fig.44. In certain embodiments, cylinder 332 is the only cylinder coupled to fitting 274 to relieve tension during a single step. In certain embodiments, cylinder 332 includes one or more cylinders coupled to fitting 274 to ease tension during several stages.

The second cylinder 332B may be welded locally to the end face of the first cylinder 332A. As shown in FIG. 44, the longitudinal length of the finished cylinder 332 may exceed the length of the protruding cores 214A, 214B, 214C. Therefore, the cores may be within the boundaries of the cylinder 332.

After forming the cylinder 332, the insulating material 256 is added to the cylinder almost to the level of the upper part of the cores 214A, 214B, 214C and the busbar 330, as shown in Fig. 45. In some embodiments, the insulating material 256, which is at the level of FIG. 45, is compressed (for example, mechanically pressed). On Fig shows one of the embodiments of the compression tool 334B, which can be used to compress the insulating material 256. The compression tool 334B may have an annular part that allows you to install the tool on the bus bar 330 and the cores 214A, 214B, 214C during compression of the insulating material .

After compressing the material at the level of the upper part of the busbar 330 and the cores 214A, 214B, 214C, additional insulating material 256 is added to the cylinder to completely cover the busbar and cores, as shown in Fig. 46. Thus, the cores and busbar are essentially packaged in an insulating material 256. In some embodiments, the insulating material 256 added to the core packing cylinder 332 is compressed (for example, mechanically pressed). On Fig depicts one embodiment of a compression tool 334C, which can be used for the final compression of the insulating material 256.

After the final pressing of the insulating material 256, the end cap 272 is connected (welded) to the cylinder 332, forming a fitting 270. In some embodiments, the shape of the end cap is used as guides when installing insulated conductors 212A, 212B, 212C in the wellbore or installation device (for example, coil fitting). In certain embodiments, fitting 270 is used with insulated conductors as single-phase heaters. For example, fitting 270 may be used with two insulated conductors connected as a threaded connection within the fitting, in which one insulated conductor is used as the supply conductor and the other as the return wire. Fitting 270 can also be used with one insulated conductor, in which case the sheath of the insulated conductor is used to return current to the formation surface.

Mechanical compression of the insulating material inside the fitting 270 allows you to get a fitting with a higher mechanical strength from breakdown voltage and / or higher operating temperature than fittings filled with insulating material and subjected to vibration to compress the insulating material. For example, fitting 270 can be operated at voltages greater than about 6 kV and temperatures greater than about 700 ° C. Since fitting 270 (end termination of the fitting) can be operated at temperatures above about 700 ° C, the fitting can be used in heated layers of a subterranean formation (e.g., pyrolyzed layers). Therefore, the end face of the heater does not need to be placed in the colder part of the formation, and the heater wellbore may not need to be drilled so deep in the formation or in different types of formations.

In some embodiments, a failed three-phase heater is converted to a single-phase heater using the same power source. If, for example, one section of a three-phase heater fails (shorts to ground), then the other two sections of the heater can be used as a single-phase heater, in which one section acts as a supply conductor and the other section acts as a return wire. To transfer the heater into single-phase mode, a resistor with a high impedance is installed between the neutral wire of the three-phase power source (transformer) and the shorted circuit of the heater. The resistor is installed in series with the heater circuit shorted to ground. Due to the high resistance of the resistor, the voltage is removed from the circuit shorted to ground and fed to the resistor. Thus, the resistor is used to remove power from the circuit shorted to ground so that a weak current passes through the shorted circuit to ground or the current does not pass at all. After connecting the resistor between the neutral wire of the transformer and the part shorted to ground, the remaining two sections of the heater operate in single-phase mode so that the current passing through one section passes through the end termination and returns to another section.

When using the heater in three-phase mode, the voltage at the termination is close to zero, since the three sections are phase shifted by 120 ° to balance the voltages between the three sections (the voltage cannot be completely zero if there is any imbalance between the sections of the circuit). The termination of a three-phase heater is usually insulated from ground. When the heater is switched to single-phase mode, the voltage at the termination increases from a voltage of almost zero to about half the output voltage of the power source. The voltage at the end termination increases during operation in single-phase mode, since in this case the current passes through two working sections linearly, and the end termination is at the midpoint of the circuit. For example, when operating in three-phase mode from a power supply of 480 V, the voltage in each of the sections can be approximately 277 V, and at the end termination, at the bottom of the heater, approximately 0 V. After switching to single-phase operation, with a resistor in series with a closed on the mass of the plot, the plots operating in single-phase mode create a voltage of approximately 240 V at the termination, at the bottom of the heater.

Since the voltage for heating an underground or hydrocarbon-containing formation to the temperature of mobility and / or pyrolysis is usually very high due to the large length of the conductors (for example, about 1 kV or higher), the termination, so that it can be used in single-phase mode, must withstand even higher voltage. Terminations currently used for underground heating typically cannot be operated at such high voltages. Meanwhile, since fitting 270 can operate at voltages above 6 kV, fitting 270 allows you to convert a failed high-voltage three-phase underground heater for operation in a single-phase mode. Examples

The following are non-limiting examples.

Samples using the fitting embodiment of FIG. 5 Using a fitting embodiment of 250 similar to the embodiment of FIG. 5, samples were made using a hydraulic press with a medium voltage insulated conductor suitable for use in an underground heater located on one side of the fitting, and medium-voltage insulated conductor, suitable for use as a cable in an overlapping rock, located on the other side of the fitting. Magnesium oxide was used as an insulating material in the fitting. The length of the samples from one end of the mineral-insulated conductor to the other was 1.829 m. Before conducting the electrical tests, the samples were placed in a 1.981-m long oven, dried at 454.4 ° C for 30 hours. After cooling to 65.56 ° C, the ends of the mineral-insulated conductors were sealed with epoxy resin. After that, the samples were placed in a 0.9144 m long furnace to heat the samples, and then voltage was applied to the samples using a 5 kV high voltage meter (maximum) capable of measuring both the general and actual components of the leakage current. Three thermocouples were mounted on the samples and averaged for temperature measurements. Samples were placed in the furnace so that the fitting was in the center of the furnace. Using a high voltage meter, the parameters of the external direct current and the leakage currents of the alternating current were measured.

A total of eight samples were tested at a temperature of about 537.8 ° C and a voltage of up to 5 kV. For one sample tested at 5 kV, the leakage current was 2.28 mA, and for another, the leakage current was 6.16 mA. Three other samples tested at a voltage of 5 kV, whose cores were connected in parallel, had a total leakage current of 11.7 mA or 3.9 mA on average per cable, while the three samples were stable. Three more samples tested at 4.4 kV, the cores of which were connected in parallel, had a combined leakage current of 4.39 mA, but they could not withstand a higher voltage without opening the high voltage meter (this occurred when the leakage current exceeded 40 mA ) One of the samples tested at 5 kV was additionally tested at ambient temperature before breakdown. The breakdown occurred at a voltage of 11 kV.

Only eleven other samples were made for additional breakdown tests at ambient temperature. In three samples, the mineral insulation of insulated conductors was cut perpendicular to the shell, while in eight other samples, the mineral insulation of insulated conductors was cut at an angle of 30 ° to the shell. Of the first three samples with a perpendicular cut, the first sample withstood up to 10.5 kV before the breakdown, the second sample withstood up to 8 kV until the breakdown, while the third sample withstood only 500 V before the breakdown, which indicates production defect in the third sample . Of the eight samples with a 30 ° cut, two samples withstood a voltage of 10 kV before the breakdown, three samples withstood a voltage from 8 kV to 9.5 kV until the breakdown, and three samples could not withstand voltage or withstand voltage less than 750 V, which indicates production defect these three samples. Samples using the fitting embodiment of FIG. 8B. Three samples were manufactured using the fitting embodiment of 270, similar to the embodiment of FIG. 8B. Samples were made with two insulated conductors instead of three and were tested for breakdown at ambient temperature. One sample withstood a voltage of 5 kV before the breakdown, the second sample withstood a voltage of 4.5 kV before the breakdown, and the third sample could only withstand a voltage of 500 V, which indicates manufacturing defects.

Samples using the fitting embodiment of FIGS. 14 and 15 Samples using the fitting embodiment of FIG. 298, similar to the embodiment of FIGS. 14 and 15, were used to connect two insulated conductors with an outer diameter of 3.048 cm and a core diameter of 1.778 cm. As an electrical insulating The material was used MgO powder (Muscle Shoals Minerals, Greenville, Tennessee, USA). The fitting was made of 347H stainless steel pipes, its external diameter was 3.81 cm, the wall thickness was 3.175 mm, and its length was 17.78 cm. The samples were placed in a furnace, heated to 565.6 ° C and passed a test cycle with different voltages up to 3.4 kV The samples turned out to be operable at all voltages, but could not withstand a higher voltage without opening the high voltage meter.

During the second test, samples similar to those discussed above underwent a short cycle of bending fatigue tests and then underwent electrical tests in a furnace. Such samples were placed in an oven, heated to 565.6 ° C and passed a test cycle with different voltages of 350 V, 600 V, 800 V, 1000 V, 1200 V, 1400 V, 1600 V, 1900 V, 2200 V and 2500 V The value of the leakage currents and the stability of the samples turned out to be acceptable up to a voltage of 1900 V. Using methods to further reduce the intensity of the electric field, such as mowing, smoothing or rounding the edges of the fitting or adding attenuators of the electric field inside the fitting, allows you to expand the working range of the fitting.

It should be understood that the invention is not limited to the particular systems considered, which, of course, may differ. It should be understood that the terminology used here refers only to the description of specific embodiments and is not restrictive. In the present description of the invention, the singular forms of the articles "a", "an" and "the" include the plural forms, unless the context directly indicates otherwise. For example, a reference to a “core” includes a combination of two or more cores, and a reference to a “material” includes a mixture of materials.

After reading the present description of the invention, other modifications and alternative embodiments of various aspects of the invention will become apparent to those skilled in the art.

Therefore, the present description of the invention should be considered solely as illustrative, the purpose of which is to explain to specialists in this field of technology a General approach for implementing the invention. It should be understood that the forms of the invention shown and discussed herein are currently preferred options for its implementation. Elements and materials may be replaced by other elements and materials depicted and discussed herein, the order of parts and processes may be changed, and some features of the invention may be used individually, at the discretion of those skilled in the art who have read the present description of the invention. Changes may be made to the elements discussed herein without departing from the scope and spirit of the invention as set forth in the appended claims.

Claims (13)

1. The method of connecting the ends of two insulated conductors, including:
connecting the end portion of the core of the first insulated conductor with the end portion of the core of the second insulated conductor, with at least a portion of the end portions of the cores at least partially exposed;
placement of electrical insulation material over exposed core sections;
placing the sleeve over the end sections of two connected insulated conductors, the sleeve having one or more raised sections, while the end sections contain bare core sections;
connection of the sleeve with the shells of insulated conductors; and
mechanical compression of the raised portions of the sleeve until the raised portions of the sleeve have a diameter substantially similar to the diameter of the rest of the sleeve, and when compressing the raised portions of the sleeve, the insulating material is compressed inside the sleeve. 2. The method according to claim 1, in which the mechanical compression of the raised sections of the sleeve is a radial compression of the raised sections. 3. The method according to p. 1, in which the sleeve has such a length and is arranged so that the length of the sleeve essentially corresponds to the gap between the bare parts of insulated conductors. 4. The method according to p. 1, in which at least one of the insulated conductors contains a core at least partially surrounded by an electrical insulator and an outer shell, and the outer shell at least partially surrounds the electrical insulator. 5. The method according to claim 1, further comprising exposing the core of at least one of the insulated conductors by removing part of the insulator and the outer shell surrounding the core at the end of at least one of the insulated conductors. 6. The method according to p. 1, in which the insulating material is blocks of insulating material and / or powder insulating material. 7. The method according to p. 1, in which the insulating material is blocks of insulating material, the shape of the inner surfaces of which corresponds to the outer surfaces of the end sections of at least partially exposed cores. 8. The method according to claim 1, further comprising connecting one or more strain relief bushings with at least one of the insulated conductors near or adjacent to the outer sleeve. 9. The method according to p. 1, in which the sleeve is welded to the shells of insulated conductors. 10. The method according to p. 1, further comprising applying pressure to the sleeve for additional pressing the sleeve into the powder material and additional pressing of the powder material. 11. The method according to p. 1, further comprising forming at least one bevel at the end portion of at least one of the insulated conductors. 12. The method according to p. 1, in which the inside of the sleeve additionally has a compressed insulating material, while the insulating material has a density that is at least about 15% of the density of at least one of the insulated conductors. 13. A method of treating an underground formation, including:
the placement of one or more heaters in a hydrocarbon reservoir, while one of the heaters is made by the method according to any one of paragraphs. 1-12; and
providing heat transfer from one or more heaters to one or more sections of the hydrocarbon reservoir.

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