[go: up one dir, main page]
More Web Proxy on the site http://driver.im/

WO2018031294A1 - Câble isolé à isolation minérale de type coaxial, à moyenne tension, à haute puissance et à couches multiples - Google Patents

Câble isolé à isolation minérale de type coaxial, à moyenne tension, à haute puissance et à couches multiples Download PDF

Info

Publication number
WO2018031294A1
WO2018031294A1 PCT/US2017/044878 US2017044878W WO2018031294A1 WO 2018031294 A1 WO2018031294 A1 WO 2018031294A1 US 2017044878 W US2017044878 W US 2017044878W WO 2018031294 A1 WO2018031294 A1 WO 2018031294A1
Authority
WO
WIPO (PCT)
Prior art keywords
electrical conductor
formation
elongated electrical
elongated
heater
Prior art date
Application number
PCT/US2017/044878
Other languages
English (en)
Inventor
David Booth Burns
Robert Guy Harley
Dhruv Arora
Kui BAO
Christopher Kelvin Harris
Original Assignee
Shell Oil Company
Shell Internationale Research Maatschappij B.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shell Oil Company, Shell Internationale Research Maatschappij B.V. filed Critical Shell Oil Company
Publication of WO2018031294A1 publication Critical patent/WO2018031294A1/fr

Links

Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
    • E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
    • E21B43/2401—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection by means of electricity
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/04—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material

Definitions

  • the present invention relates to systems and methods used for heating subsurface formations. More particularly, the invention relates to systems and methods using insulated conductors (mineral insulated conductors) to heat subsurface formations containing hydrocarbons.
  • insulated conductors mineral insulated conductors
  • Heating hydrocarbon containing formations may be a very effective way of producing oil and gas from heavy oil formations and/or oil shale formations that have a very high carbon number, and in the case of extra-heavy oil formations, a very high viscosity.
  • the heating process may substantially lower the viscosity of heavy oil and, provided that the temperature reached is sufficiently high and is maintained for a sufficient length of time, an in situ upgrading process (IUP) may also occurs.
  • IUP in situ upgrading process
  • the IUP may produce high quality lighter oil and leave heavy coke residue behind in the subsurface.
  • chemical conversion for example, pyrolysis
  • This process may be known as an in situ conversion process (ICP).
  • ICP in situ conversion process
  • One principal type of heater that enables IUP and/or ICP in subsurface formations is a mineral insulated (MI) cable heater.
  • Heaters such as mineral insulated (MI) cables (for example, insulated conductor heaters) may be placed in subsurface wellbores in hydrocarbon containing formations to provide heat to the formation.
  • MI mineral insulated
  • heaters which may be used to heat the formation. Examples of in situ processes utilizing downhole heaters are illustrated in U.S. Patent Nos. 2,634,961 to Ljungstrom; 2,732,195 to Ljungstrom;
  • MI cables for use in subsurface applications may be longer, may have larger outside diameters, and may operate at higher voltages and temperatures than what is typical in the MI cable industry.
  • long heaters may require higher voltages to provide enough power to the farthest ends of the heaters.
  • the coupling of multiple MI cable sections may be needed to make MI cables with sufficient length to reach the depths and distances needed to heat the subsurface efficiently and to couple segments with different functions, such as lead-in cables coupled to heater sections.
  • Embodiments described herein generally relate to systems, methods, and heaters for treating a subsurface formation. Embodiments described herein also generally relate to heaters that have novel components therein. Such heaters can be obtained by using the systems and methods described herein.
  • the invention provides one or more systems, methods, and/or heaters.
  • the systems, methods, and/or heaters are used for treating a subsurface formation.
  • a heater configured to heat a subsurface formation includes: a first elongated electrical conductor; a first electrical insulator at least partially surrounding the first elongated electrical conductor; a second elongated electrical conductor at least partially surrounding the first electrical insulator; a second electrical insulator at least partially surrounding the second elongated electrical conductor; and an electrically conductive sheath at least partially surrounding the second electrical insulator; wherein the first elongated electrical conductor and the second elongated electrical conductor are electrically coupled at an end of the heater configured to be distal from a surface of the subsurface formation, and wherein the first elongated electrical conductor and the second elongated electrical conductor are configured to provide resistive heat output to heat at least a portion of the subsurface formation when electrical current is applied to the first elongated electrical conductor and the second elongated electrical conductor.
  • a method for heating a subsurface formation includes: providing electrical current to a heater at least partially located in an opening in a hydrocarbon containing layer of the subsurface formation, the opening extending from a surface of the formation through an overburden section of the formation and into the hydrocarbon containing layer of the formation, the heater including: a first elongated electrical conductor; a first electrical insulator at least partially surrounding the first elongated electrical conductor; a second elongated electrical conductor at least partially surrounding the first electrical insulator; a second electrical insulator at least partially surrounding the second elongated electrical conductor; and an electrically conductive sheath at least partially surrounding the second electrical insulator; wherein the first elongated electrical conductor and the second elongated electrical conductor are electrically coupled at an end of the heater distal from the surface of the formation, wherein providing electrical current to the heater includes providing electrical current to the first elongated electrical conductor and the second elongated electrical conductor such that the first
  • a system for heating a subsurface formation includes: an opening in a hydrocarbon containing layer of the subsurface formation, the opening extending from a surface of the formation through an overburden section of the formation and into the hydrocarbon containing layer of the formation; a heater placed in the opening, the heater including: a first elongated electrical conductor; a first electrical insulator at least partially surrounding the first elongated electrical conductor; a second elongated electrical conductor at least partially surrounding the first electrical insulator; a second electrical insulator at least partially surrounding the second elongated electrical conductor; and an electrically conductive sheath at least partially surrounding the second electrical insulator; wherein the first elongated electrical conductor and the second elongated electrical conductor are electrically coupled at an end of the heater distal from the surface of the subsurface formation; and a single phase power source electrically coupled to the first elongated electrical conductor and the second elongated electrical conductor, wherein the single phase power source
  • features from specific embodiments may be combined with features from other embodiments.
  • features from one embodiment may be combined with features from any of the other embodiments.
  • treating a subsurface formation is performed using any of the methods, systems, power supplies, or heaters described herein.
  • FIG. 1 shows a schematic view of an embodiment of a portion of an in situ heat treatment system for treating a hydrocarbon containing formation.
  • FIG. 2 depicts a side-view representation of an embodiment of two single cable insulated conductors positioned in an opening in a subsurface formation.
  • FIG. 3 depicts a perspective view representation of an end portion of an embodiment of single cable insulated conductor.
  • FIG. 4 depicts an end view representation of an embodiment of a double insulated conductor.
  • FIG. 5 depicts a side-view representation of another embodiment of a single cable insulated conductor positioned in an opening in a subsurface formation.
  • FIG. 6 depicts an enlarged cross-sectional side view of a portion of an insulated conductor.
  • FIG. 7 depicts an end view representation of an embodiment of a single cable, double insulated conductor inside a canister.
  • FIG. 8 depicts an end view representation of an embodiment of a single cable, double insulated conductor with a tubular core.
  • FIG. 9 depicts a representation of an embodiment of an origin of the electric field in an electrical insulator.
  • FIG. 10 depicts E pea k, E avg and Ebreak from breakdown test data versus index.
  • FIG. 11 depicts a side-view representation of a single cable, double insulated conductor end termination.
  • FIG. 12 depicts a plot of E pea k, E avg , and Ebreak versus different lengths of insulated conductor.
  • FIG. 13 depicts another plot of E pea k, E avg , and Ebreak versus different lengths of insulated conductor.
  • FIG. 14 depicts the temperature distribution along the radius r at time 100.5 s for the thermal runaway simulation.
  • FIG. 15 depicts the temperature distribution along the radius r at time 571 s for the thermal runaway simulation.
  • FIG. 16 depicts the temperature of a core and a jacket versus the heat delivery rate.
  • the following description generally relates to systems and methods for treating hydrocarbons in the formations. Such formations may be treated to yield hydrocarbon products, hydrogen, and other products.
  • Alternating current refers to a time-varying current that reverses direction substantially sinusoidally. AC produces skin effect electricity flow in a ferromagnetic conductor.
  • Coupled means either a direct connection or an indirect connection (for example, one or more intervening connections) between one or more objects or components.
  • the phrase “directly connected” means a direct connection between objects or components such that the objects or components are connected directly to each other so that the objects or components operate in a "point of use” manner.
  • a "formation” includes one or more hydrocarbon containing layers, one or more non-hydrocarbon layers, an overburden, and/or an underburden.
  • Hydrocarbon layers refer to layers in the formation that contain hydrocarbons. The hydrocarbon layers may contain non-hydrocarbon material and hydrocarbon material.
  • the "overburden” and/or the "underburden” include one or more different types of impermeable materials.
  • the overburden and/or underburden may include rock, shale, mudstone, or wet/tight carbonate.
  • the overburden and/or the underburden may include a hydrocarbon containing layer or hydrocarbon containing layers that are relatively impermeable and are not subjected to temperatures during in situ heat treatment processing that result in significant characteristic changes of the hydrocarbon containing layers of the overburden and/or the underburden.
  • the underburden may contain shale or mudstone, but the underburden is not allowed to heat to pyrolysis temperatures during the in situ heat treatment process. In some cases, the overburden and/or the underburden may be somewhat permeable.
  • Formation fluids refer to fluids present in a formation and may include pyrolyzation fluid, synthesis gas, mobilized hydrocarbons, and water (steam). Formation fluids may include hydrocarbon fluids as well as non-hydrocarbon fluids.
  • the term "mobilized fluid” refers to fluids in a hydrocarbon containing formation that are able to flow as a result of thermal treatment of the formation.
  • a "heat source” is any system for providing heat to at least a portion of a formation substantially by conductive and/or radiative heat transfer.
  • a heat source may include electrically conducting materials and/or electric heaters such as an insulated conductor.
  • a heat source may also include systems that generate heat by burning a fuel external to or in a formation. The systems may be surface burners, downhole gas burners, flameless distributed combustors, and natural distributed combustors.
  • heat provided to or generated in one or more heat sources may be supplied by other sources of energy. The other sources of energy may directly heat a formation, or the energy may be applied to a transfer medium that directly or indirectly heats the formation.
  • one or more heat sources that are applying heat to a formation may use different sources of energy.
  • some heat sources may supply heat from electrically conducting materials, electric resistance heaters, some heat sources may provide heat from combustion, and some heat sources may provide heat from one or more other energy sources (for example, chemical reactions, solar energy, wind energy, biomass, or other sources of renewable energy).
  • a chemical reaction may include an exothermic reaction (for example, an oxidation reaction).
  • a heat source may also include an electrically conducting material and/or a heater that provides heat to a zone proximate 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 a near wellbore region.
  • Heaters may be, but are not limited to, electric heaters, burners, combustors that react with material in or produced from a formation, and/or combinations thereof.
  • Hydrocarbons are generally defined as molecules formed primarily by carbon and hydrogen atoms. Hydrocarbons may also include other elements such as, but not limited to, halogens, metallic elements, nitrogen, oxygen, and/or sulfur. Hydrocarbons may be, but are not limited to, kerogen, bitumen, pyrobitumen, oils, natural mineral waxes, and asphaltites. Hydrocarbons may be located in or adjacent to mineral matrices in the earth. Matrices may include, but are not limited to, sedimentary rock, sands, silicilytes, carbonates, diatomites, and other porous media. "Hydrocarbon fluids” are fluids that include hydrocarbons. Hydrocarbon fluids may include, entrain, or be entrained in non- hydrocarbon fluids such as hydrogen, nitrogen, carbon monoxide, carbon dioxide, hydrogen sulfide, water, and ammonia.
  • An "in situ conversion process” refers to a process of heating a hydrocarbon containing formation from heat sources to raise the temperature of at least a portion of the formation above a pyrolysis temperature so that pyrolyzation fluid is produced in the formation.
  • An "in situ heat treatment process” refers to a process of heating a hydrocarbon containing formation with heat sources to raise the temperature of at least a portion of the formation above a temperature that results in mobilized fluid, visbreaking, and/or pyrolysis of hydrocarbon containing material so that mobilized fluids, visbroken fluids, and/or pyrolyzation fluids are produced in the formation.
  • Insulated conductor refers to any elongated material that is able to conduct electricity and that is covered, in whole or in part, by an electrically insulating material.
  • Pyrolysis is the breaking of chemical bonds due to the application of heat.
  • pyrolysis may include transforming a compound into one or more other substances by heat alone. Heat may be transferred to a section of the formation to cause pyrolysis.
  • Pyrolyzation fluids or "pyrolysis products” refers to fluid produced substantially during pyrolysis of hydrocarbons. Fluid produced by pyrolysis reactions may mix with other fluids in a formation. The mixture would be considered pyrolyzation fluid or pyrolyzation product.
  • pyrolysis zone refers to a volume of a formation (for example, a relatively permeable formation such as a tar sands formation) that is reacted or reacting to form a pyrolyzation fluid.
  • wellbore refers to a hole in a formation made by drilling or insertion of a conduit into the formation.
  • a wellbore may have a substantially circular cross section, or another cross-sectional shape.
  • wellbore and opening when referring to an opening in the formation may be used interchangeably with the term “wellbore.”
  • a formation may be treated in various ways to produce many different products. Different stages or processes may be used to treat the formation during an in situ heat treatment process.
  • one or more sections of the formation are solution mined to remove soluble minerals from the sections. Solution mining minerals may be performed before, during, and/or after the in situ heat treatment process.
  • the average temperature of one or more sections being solution mined may be maintained below about 120 °C.
  • one or more sections of the formation are heated to remove water from the sections and/or to remove methane and other volatile hydrocarbons from the sections.
  • the average temperature may be raised from ambient temperature to temperatures below about 220 °C during removal of water and volatile hydrocarbons.
  • one or more sections of the formation are heated to temperatures that allow for movement and/or visbreaking of hydrocarbons in the formation.
  • the average temperature of one or more sections of the formation are raised to mobilization temperatures of hydrocarbons in the sections (for example, to temperatures ranging from 100 °C to 250 °C, from 120 °C to 240 °C, or from 150 °C to 230 °C).
  • one or more sections are heated to temperatures that allow for pyrolysis reactions in the formation.
  • the average temperature of one or more sections of the formation may be raised to pyrolysis temperatures of hydrocarbons in the sections (for example, temperatures ranging from 230 °C to 900 °C, from 240 °C to 400 °C or from 250 °C to 350 °C).
  • Heating the hydrocarbon containing formation with a plurality of heat sources may establish thermal gradients around the heat sources that raise the temperature of hydrocarbons in the formation to desired temperatures at desired heating rates.
  • the rate of temperature increase through the mobilization temperature range and/or the pyrolysis temperature range for desired products may affect the quality and quantity of the formation fluids produced from the hydrocarbon containing formation.
  • Slowly raising the temperature of the formation to mobilization temperatures and/or pyrolysis temperatures may allow for the production of high quality, high API gravity hydrocarbons from the formation.
  • Slowly raising the temperature of the formation through the mobilization temperature range and/or pyrolysis temperature range may allow for the removal of a large amount of the hydrocarbons present in the formation as hydrocarbon product.
  • a portion of the formation is heated to a desired temperature instead of slowly heating the temperature through a temperature range.
  • the desired temperature is 300 °C, 325 °C, or 350 °C. Other temperatures may be selected as the desired temperature.
  • Products from mobilization of hydrocarbons and/or pyrolysis of hydrocarbons may be produced from the formation through production wells.
  • the average temperature of one or more sections is raised to mobilization temperatures and hydrocarbons are produced from the production wells.
  • the average temperature of one or more of the sections may be raised to pyrolysis temperatures after production due to mobilization decreases below a selected value.
  • the average temperature of one or more sections may be raised to pyrolysis temperatures without significant production before reaching pyrolysis temperatures.
  • Formation fluids including pyrolysis products may be produced through the production wells.
  • the average temperature of one or more sections may be raised to temperatures sufficient to allow synthesis gas production after mobilization and/or pyrolysis.
  • hydrocarbons may be raised to temperatures sufficient to allow synthesis gas production without significant production before reaching the temperatures sufficient to allow synthesis gas production.
  • synthesis gas may be produced in a temperature range from about 400 °C to about 1200 °C, about 500 °C to about 1100 °C, or about 550 °C to about 1000 °C.
  • a synthesis gas generating fluid for example, steam and/or water
  • Synthesis gas may be produced from production wells 206.
  • Solution mining removal of volatile hydrocarbons and water, mobilizing hydrocarbons, pyrolyzing hydrocarbons, generating synthesis gas, and/or other processes may be performed during the in situ heat treatment process.
  • some processes may be performed after the in situ heat treatment process.
  • Such processes may include, but are not limited to, recovering heat from treated sections, storing fluids (for example, water and/or hydrocarbons) in previously treated sections, and/or sequestering carbon dioxide in previously treated sections.
  • FIG. 1 depicts a schematic view of an embodiment of a portion of an in situ heat treatment system for treating the hydrocarbon containing formation.
  • the in situ heat treatment system may include barrier wells 200.
  • Barrier wells may be used to form a barrier around a treatment area. The barrier may inhibit fluid flow into and/or out of the treatment area.
  • Barrier wells 200 may include, but are not limited to, dewatering wells, vacuum wells, capture wells, injection wells, grout wells, freeze wells, or combinations thereof.
  • barrier wells 200 are dewatering wells. Dewatering wells may remove liquid water and/or inhibit liquid water from entering a portion of the formation to be heated, or to the formation being heated.
  • barrier wells 200 are shown extending only along one side of heat sources 202, but barrier wells 200 typically encircle all heat sources 202 used, or to be used, to heat a treatment area of the formation.
  • Heat sources 202 may be placed in at least a portion of the formation.
  • heat sources 202 include heaters such as insulated conductors. Heat sources 202 may also include other types of heaters. Heat sources 202 may provide heat to at least a portion of the formation to heat hydrocarbons in the formation. Energy may be supplied to heat sources 202 through supply lines 204. Supply lines 204 may be structurally different depending on the type of heat source or heat sources used to heat the formation. Supply lines 204 for heat sources 202 may transmit electricity for electric heaters, may transport fuel for combustors, or may transport heat exchange fluid that is circulated in the formation. In some embodiments, electricity for an in situ heat treatment process may be provided by a nuclear power plant or nuclear power plants. The use of nuclear power may allow for reduction or elimination of carbon dioxide emissions from the in situ heat treatment process.
  • Heat sources 202 may be turned on before, at the same time, or during a dewatering process.
  • Computer simulations may model formation response to heating. The computer simulations may be used to develop a pattern and time sequence for activating heat sources 202 in the formation so that geomechanical motion of the formation does not adversely affect the functionality of heat sources 202, production wells 206, and other equipment in the formation.
  • Heating the formation may cause an increase in permeability and/or porosity of the formation.
  • Increases in permeability and/or porosity may result from a reduction of mass in the formation due to vaporization and removal of water, removal of hydrocarbons, and/or creation of fractures.
  • Fluid may flow more easily in the heated portion of the formation because of the increased permeability and/or porosity of the formation.
  • Fluid in the heated portion of the formation may move a considerable distance through the formation because of the increased permeability and/or porosity. The considerable distance may be over 1000 m depending on various factors, such as permeability of the formation, properties of the fluid, temperature of the formation, and pressure gradient allowing movement of the fluid.
  • the ability of fluid to travel considerable distance in the formation allows production wells 206 to be spaced relatively far apart in the formation.
  • Production wells 206 may be used to remove formation fluid from the formation.
  • at least one of the production wells 206 includes heat source 202.
  • Heat source 202 in production well 206 may heat one or more portions of the formation at or near the production well.
  • the amount of heat supplied to the formation from production well 206 per meter of the production well is less than the amount of heat applied to the formation from heat source 202 that heats the formation per meter of the heat source.
  • Heat applied to the formation from production well 206 may increase formation permeability adjacent to the production well by vaporizing and removing liquid phase fluid adjacent to the production well and/or by increasing the permeability of the formation adjacent to the production well by formation of macro and/or micro fractures.
  • More than one heat source 202 may be positioned in production well 206.
  • Heat source 202 in a lower portion of production well 206 may be turned off when superposition of heat from adjacent heat sources heats the formation sufficiently to counteract benefits provided by heating the formation with the production well.
  • heat source 202 in an upper portion of production well 206 may remain on after the heat source in the lower portion of the production well is deactivated. Heat source in the upper portion of production well 206 may inhibit condensation and reflux of formation fluid.
  • heat source 202 in production well 206 allows for vapor phase removal of formation fluids from the formation.
  • Providing heating at or through production well 206 may: (1) inhibit condensation and/or refluxing of production fluid when such production fluid is moving in production well 206 proximate the overburden, (2) increase heat input into the formation, (3) increase production rate from production well 206 as compared to a production well without a heat source 202, (4) inhibit condensation of high carbon number compounds (C6 hydrocarbons and above) in production well 206, and/or (5) increase formation permeability at or proximate production well 206.
  • C6 hydrocarbons and above high carbon number compounds
  • Subsurface pressure in the formation may correspond to the fluid pressure generated in the formation. As temperatures in the heated portion of the formation increase, the pressure in the heated portion may increase as a result of thermal expansion of in situ fluids, increased fluid generation and vaporization of water. Controlling rate of fluid removal from the formation may allow for control of pressure in the formation.
  • Pressure in the formation may be determined at a number of different locations, such as near or at production wells 206, near or at heat sources 202, or at monitor wells.
  • production of hydrocarbons from the formation may be inhibited until at least some hydrocarbons in the formation have been mobilized and/or pyrolyzed.
  • Formation fluid may be produced from the formation when the formation fluid is of a selected quality.
  • the selected quality includes an API gravity of at least about 20°, 30°, or 40°.
  • Inhibiting production until at least some hydrocarbons are mobilized and/or pyrolyzed may increase conversion of heavy hydrocarbons to light hydrocarbons. Inhibiting initial production may minimize the production of heavy hydrocarbons from the formation. Production of substantial amounts of heavy hydrocarbons may require expensive equipment and/or reduce the life of production equipment.
  • hydrocarbons in the formation may be heated to mobilization and/or pyrolysis temperatures before substantial permeability has been generated in the heated portion of the formation.
  • An initial lack of permeability may inhibit the transport of generated fluids to production wells 206.
  • fluid pressure in the formation may increase proximate heat sources 202.
  • the increased fluid pressure may be released, monitored, altered, and/or controlled through one or more heat sources 202.
  • selected heat sources 202 or separate pressure relief wells may include pressure relief valves that allow for removal of some fluid from the formation.
  • pressure generated by expansion of mobilized fluids, pyrolysis fluids or other fluids generated in the formation may be allowed to increase although an open path to production wells 206 or any other pressure sink may not yet exist in the formation.
  • the fluid pressure may be allowed to increase towards a lithostatic pressure.
  • Fractures in the hydrocarbon containing formation may form when the fluid approaches the lithostatic pressure.
  • fractures may form from heat sources 202 to production wells 206 in the heated portion of the formation.
  • the generation of fractures in the heated portion may relieve some of the pressure in the portion.
  • Pressure in the formation may have to be maintained below a selected pressure to inhibit unwanted production, fracturing of the overburden or underburden, and/or coking of hydrocarbons in the formation.
  • pressure in the formation may be varied to alter and/or control a composition of formation fluid produced, to control a percentage of condensable fluid as compared to non-condensable fluid in the formation fluid, and/or to control an API gravity of formation fluid being produced. For example, decreasing pressure may result in production of a larger condensable fluid component.
  • the condensable fluid component may contain a larger percentage of olefins.
  • pressure in the formation may be maintained high enough to promote production of formation fluid with an API gravity of greater than 20°. Maintaining increased pressure in the formation may inhibit formation subsidence during in situ heat treatment. Maintaining increased pressure may reduce or eliminate the need to compress formation fluids at the surface to transport the fluids in collection piping 208 or other conduits to treatment facilities 210.
  • Maintaining increased pressure in a heated portion of the formation may surprisingly allow for production of large quantities of hydrocarbons of increased quality and of relatively low molecular weight. Pressure may be maintained so that formation fluid produced has a minimal amount of compounds above a selected carbon number.
  • the selected carbon number may be at most 25, at most 20, at most 12, or at most 8.
  • Some high carbon number compounds may be entrained in vapor in the formation and may be removed from the formation with the vapor. Maintaining increased pressure in the formation may inhibit entrainment of high carbon number compounds and/or multi-ring hydrocarbon compounds in the vapor.
  • High carbon number compounds and/or multi-ring hydrocarbon compounds may remain in a liquid phase in the formation for significant time periods. The significant time periods may provide sufficient time for the compounds to pyrolyze to form lower carbon number compounds.
  • Generation of relatively low molecular weight hydrocarbons is believed to be due, in part, to autogenous generation and reaction of hydrogen in a portion of the hydrocarbon containing formation.
  • maintaining an increased pressure may force hydrogen generated during pyrolysis into the liquid phase within the formation.
  • Heating the portion to a temperature in a pyrolysis temperature range may pyrolyze hydrocarbons in the formation to generate liquid phase pyrolyzation fluids.
  • the generated liquid phase pyrolyzation fluids components may include double bonds and/or radicals.
  • Hydrogen (3 ⁇ 4) in the liquid phase may reduce double bonds of the generated pyrolyzation fluids, thereby reducing a potential for polymerization or formation of long chain compounds from the generated pyrolyzation fluids.
  • 3 ⁇ 4 may also neutralize radicals in the generated pyrolyzation fluids.
  • 3 ⁇ 4 in the liquid phase may inhibit the generated pyrolyzation fluids from reacting with each other and/or with other compounds in the formation.
  • Formation fluid produced from production wells 206 may be transported through collection piping 208 to treatment facilities 210.
  • Formation fluids may also be produced from heat sources 202.
  • fluid may be produced from heat sources 202 to control pressure in the formation adjacent to the heat sources.
  • Fluid produced from heat sources 202 may be transported through tubing or piping to collection piping 208 or the produced fluid may be transported through tubing or piping directly to treatment facilities 210.
  • Treatment facilities 210 may include separation units, reaction units, upgrading units, fuel cells, turbines, storage vessels, and/or other systems and units for processing produced formation fluids.
  • Treatment facilities 210 may form transportation fuel from at least a portion of the hydrocarbons produced from the formation.
  • the transportation fuel may be jet fuel, such as JP-8.
  • insulated conductors for example, MI (mineral insulated) cables
  • MI mineral insulated
  • an insulated conductor includes an inner electrical conductor (core) surrounded by an electrical insulator 310 (shown in FIG. 3) and an outer electrical conductor (jacket or sheath).
  • Electrical insulator 310 may include mineral insulation (for example, magnesium oxide) or other electrical insulation.
  • the insulated conductor is placed in an opening in a hydrocarbon containing formation.
  • FIG. 2 depicts a side-view representation of an embodiment of two single cable insulated conductors 300 positioned in opening 302 in subsurface formation 304.
  • Formation 304 may be a hydrocarbon containing formation.
  • opening 302 is positioned in a hydrocarbon containing layer in formation 304.
  • Insulated conductor 300 may be supported by wellhead 306 at the surface of formation 304.
  • opening 302 is an uncased opening in formation 304.
  • Placing insulated conductor 300 in uncased opening 302 may allow heat transfer from insulated conductor 300 to formation 304 by radiation as well as conduction. Using uncased opening 302 may also facilitate retrieval of insulated conductor 300 from the opening, if necessary.
  • insulated conductor 300 is placed within a casing in formation 304; may be cemented within formation 304; or may be packed in opening 302 with sand, gravel, or other fill material. Insulated conductor 300 may be supported on a support member positioned within opening 302.
  • the support member may be a cable, rod, or a conduit (for example, a pipe).
  • the support member may be made of a metal, ceramic, inorganic material, or combinations thereof. Because portions of a support member may be exposed to formation fluids and heat during use, the support member may be chemically resistant and/or thermally resistant.
  • Ties, spot welds, and/or other types of connectors may be used to couple or attach insulated conductor 300 to the support member at various locations along a length of insulated conductor 300.
  • the support member may be attached to wellhead 306 at an upper surface of formation 304.
  • insulated conductor 300 is placed in opening 302 without a support member and/or centralizers.
  • Insulated conductor 300 may have sufficient structural strength such that a support member is not needed.
  • insulated conductor 300 may have a suitable combination of temperature and corrosion resistance, creep strength, length, thickness (diameter), and metallurgy that will inhibit failure of insulated conductor 300 during use.
  • Insulated conductor 300 may, in many embodiments, have at least some flexibility to inhibit thermal expansion damage when undergoing temperature changes.
  • FIG. 3 depicts a perspective view representation of an end portion of an embodiment of a typical insulated conductor 300 (for example, an MI cable) with a single core 308.
  • Insulated conductor 300 may include core 308, electrical insulator 310, and jacket 312. Core 308 may resistively heat when an electrical current passes through the core. Alternating current and/or direct current may be used to provide power to core 308 such that core 308 resistively heats.
  • electrical insulator 310 inhibits current leakage and arcing to jacket 312.
  • Electrical insulator 310 may thermally conduct heat generated in core 308 to jacket 312.
  • Jacket 312 may radiate or conduct heat to subsurface formation 304.
  • the dimensions of core 308, electrical insulator 310, and jacket 312 of insulated conductor 300 may be selected such that insulated conductor 300 has enough strength to be self supporting even at upper working temperature limits.
  • Such insulated conductor 300 may be suspended from a wellhead (for example, wellhead 306 shown in FIG. 2) or supports positioned near an interface between an overburden and a hydrocarbon containing layer.
  • Insulated conductor 300 may be designed to operate at voltages above 1000 volts, above 1500 volts, or above 2000 volts and may operate for extended periods without failure at elevated temperatures, such as over 650 °C (about 1200 °F), over 700 °C (about 1290 °F), or over 800 °C (about 1470 °F). Insulated conductor 300 may be designed so that a maximum voltage level at a typical operating temperature does not cause substantial thermal and/or electrical breakdown of electrical insulator 310. Insulated conductor 300 may be designed such that jacket 312 does not exceed a temperature that will result in a significant reduction in corrosion resistance properties of the jacket material. In certain embodiments, insulated conductor 300 may be designed to reach temperatures within a range between about 650 °C and about 900 °C. Insulated conductors 300 having other operating ranges may be formed to meet specific operational requirements.
  • single cable insulated conductor 300 may have a single core 308.
  • insulated conductor 300 has two or more cores 308.
  • a single cable insulated conductor 300 may have three cores.
  • Each core 308 may be made of metal or another electrically conductive material. The material used to form core 308 may include, but not be limited to, nichrome, copper, nickel, carbon steel, stainless steel, and combinations or alloys thereof.
  • core 308 is chosen to have a diameter and a resistivity at operating temperatures such that its resistance, as derived from Ohm's law, makes it electrically and structurally stable for the chosen power dissipation per meter, the length of the heater, and/or the maximum voltage allowed for the core material.
  • core 308 is made of different materials along a length of insulated conductor 300.
  • a first section of core 308 may be made of a material that has a significantly lower resistance than a second section of core 308.
  • the first section may be placed adjacent to a formation layer that does not need to be heated to as high a temperature as a second formation layer that is adjacent to the second section.
  • insulated conductor 300 may be used to heat formation 304 (shown in FIG. 2) where the formation has an overburden. To avoid heating in the overburden (and wasting heat energy costs in the overburden), insulated conductor 300 may have a highly conductive core (for example, a copper core) in the overburden.
  • the copper core of insulated conductor 300 in the overburden may provide little to no heat in the overburden.
  • the copper core overburden section of insulated conductor 300 may be electrically coupled to a higher resistance core (for example, a nickel-copper alloy core) for providing heat to the hydrocarbon containing layer of formation 304 below the overburden.
  • a transition core is electrically coupled between the overburden core and the heating section (higher resistance) core.
  • the core of the transition typically bridges the materials gap between the other cores in the overburden and the heating section.
  • the resistivity of various sections of core 308 may be adjusted by varying a diameter of core 308 in addition to varying materials of core 308.
  • Electrical insulator 310 may be made of a variety of materials. Commonly used materials may include, but are not limited to, MgO, AI2O3, Zirconia, BeO, different chemical variations of Spinels, and combinations thereof. MgO may provide good thermal conductivity and electrical insulation properties. The desired electrical insulation properties include low leakage current and high dielectric strength. A low leakage current decreases the possibility of thermal breakdown and the high dielectric strength decreases the possibility of arcing across electrical insulator 310. Thermal breakdown can occur if the leakage current causes a progressive rise in the temperature of the insulator leading also to arcing across electrical insulator 310. In certain embodiments, electrical insulator 310 is made from blocks of electrical insulation material. Insulated conductors using blocks of electrical insulation material are described, for example, in U.S. Patent No. 8,502,120 to Bass et al., which is incorporated by reference as if fully set forth herein.
  • Jacket 312 may be an outer metallic layer or electrically conductive layer. Jacket 312 may be in contact with hot formation fluids. Jacket 312 may be made of material having a high resistance to corrosion at elevated temperatures. Alloys that may be used in a desired operating temperature range of jacket 312 include, but are not limited to, 304 stainless steel, 310 stainless steel, Incoloy® 800, and Inconel® 600 (Inco Alloys
  • a thickness of jacket 312 may generally vary between about 1 mm and about 2.5 mm. Larger or smaller jacket thicknesses may be used to meet specific application requirements.
  • insulated conductor 300 may be placed in opening 302 in formation 304 to form a heater in opening 302. Electrical current may be passed through insulated conductor 300 to provide resistive heat output to formation 304. Insulated conductor 300 may be electrically coupled to a power source in any convenient manner. In certain embodiments, insulated conductor 300 has a length of at least about 100 m in opening 302. In some embodiments, insulated conductor 300 is at least about 1000 m or more in length. Longer or shorter insulated conductors 300 may also be used to meet specific application needs. In some embodiments, two or more insulated conductors are coupled (for example, spliced) together to form a longer insulated conductor or a long insulated conductor heater.
  • portion 314 of insulated conductor 300 at a distal end of opening 302 (the end of opening 302 distal from the surface of formation 304) has a 180° bend (a "hairpin" bend) or turn located near a bottom of the heater for single phase operation of two single cable insulated conductors 300.
  • Each end of insulated conductor 300 may then be electrically coupled to lead-in cables at or near the surface.
  • insulated conductor 300 may not require a bottom termination; however, the 180° bend or turn may be an electrical and/or structural weakness in insulated conductor 300.
  • electrical current may pass into core 308 of insulated conductor 300 and may be returned through jacket 312 by electrically coupling core 308 to jacket 312 at the bottom of the heater (the end of the heater distal from the surface of the formation). Electrically coupling core 308 and jacket 312 in such a manner, however, produces voltage on the outer surface of jacket 312 and may increase corrosion problems in jacket 312 due to electrical current passing through jacket 312.
  • FIG. 4 depicts an end view representation of an embodiment of a single cable double insulated conductor 300' .
  • Double insulated conductor 300' may be used with a single phase power source to provide heat to a subsurface formation.
  • Double insulated conductor 300' may include two or more layers of electrical insulator separating two or more electrical conductors used for providing resistive heat output.
  • double insulated conductor 300' includes core 308, first electrical insulator 310A, electrical conductor 316, second electrical insulator 310B, and jacket 312.
  • Core 308 and electrical conductor 316 may resistively heat when an electrical current passes through core 308 and electrical conductor 316. Alternating current and/or direct current may be used to provide power to core 308 and electrical conductor 316 such that core 308 and electrical conductor 316 resistively heat.
  • FIG. 5 depicts a side-view representation of an embodiment of single cable double insulated conductor 300' positioned in opening 302 in subsurface formation 304.
  • double insulated conductor 300' has a length of at least about 100 m in opening 302.
  • double insulated conductor 300' is at least about 1000 m or more in length.
  • double insulated conductor 300' is at least about 3000 m in length. Longer or shorter double insulated conductors may also be used to meet specific application needs.
  • power source 318 is electrically coupled to double insulated conductor 300' to provide electrical power to the insulated conductor. Double insulated conductor 300' may provide resistive heat output to formation 304 using electrical power from power source 318.
  • power source 318 is a single phase electrical power source. Core 308 and electrical conductor 316, shown in FIG. 4, may be electrically coupled to allow single phase power to flow through double insulated conductor 300'.
  • core 308 at the surface of the formation may be used as a supply line for the electrical power provided to double insulated conductor 300' and electrical conductor 316, at the surface of the formation, may be used as a return for the electrical power (core 308 and electrical conductor 316 may be terminals for single phase power connections to double insulated conductor 300').
  • core 308 and electrical conductor 316 may be terminals for single phase power connections to double insulated conductor 300'.
  • core 308 and electrical conductor 316 are electrically coupled in portion 320 of double insulated conductor 300', shown in FIG. 5.
  • Portion 320 of double insulated conductor 300' may be located at or near an end of opening 302 distal from the surface of the formation.
  • Portion 320 may be an end portion or termination portion of double insulated conductor 300'.
  • FIG. 6 depicts an enlarged cross-sectional side view of portion 320 of double insulated conductor 300' .
  • coupling 322 electrically couples core 308 and electrical conductor 316 in portion 320.
  • Coupling 322 may be a conductive material that mechanical and electrically couples core 308 and electrical conductor 316.
  • Coupling 322 may be, for example, a metal piece welded or brazed to core 308 and electrical conductor 316.
  • jacket 312 includes end portion 312 A.
  • End portion 312A may close or seal off the end of double insulated conductor 300' (for example, portion 320 of double insulated conductor 300').
  • End portion 312A may be a portion of jacket 312 that is welded or otherwise coupled or attached to the elongated walls of jacket 312 after jacket 312 is formed around second electrical insulator 310B.
  • end portion 312A of jacket 312 is separated from coupling 322 by at least some of second electrical insulator 310B (or any other suitable electrical insulation).
  • End portion 312A of jacket 312 and coupling 322 may be electrically isolated by second electrical insulator 310B to inhibit electrical shorting between coupling 322 and end portion 312A and thus, inhibit electrical current from flowing through jacket 312.
  • portion 320 of double insulated conductor 300' has an outside diameter that is substantially similar to the other portions of double insulated conductor 300'.
  • double insulated conductor 300' has a substantially constant outside diameter along its entire length, including portion 320 (the end portion or end termination of double insulated conductor 300').
  • double insulated conductor 300' may have no external splices, end terminations, or other disruptions that change the outside diameter of double insulated conductor 300' along the length of double insulated conductor 300'.
  • double insulated conductor 300' has a length of at least about 100 m, at least about 1000 m, or at least about 3000 m with a substantially constant diameter along the length of double insulated conductor 300'.
  • two or more double insulated conductors are coupled (for example, spliced) together to form a longer double insulated conductor or a long double insulated conductor heater.
  • the splice(s) coupling the two or more double insulated conductors have substantially the same outside diameter as the double insulated conductors.
  • double insulated conductor 300' allows double insulated conductor 300' to be moved through lubricators, rollers, and/or other cable handling equipment without the need for special adapters and/or special techniques.
  • double insulated conductor 300' may be installed downhole inside a pressurized wellbore using a lubricator or similar device that maintains pressure control and wellbore integrity.
  • the pressurized wellbore may be, for example, a live or operating wellbore under pressure.
  • double insulated conductor 300' is installed in a downhole well environment without the need for a support member such as a canister, conduit, or other supporting structure. Such installation allows double insulated conductor 300' to be installed using, for example, coiled tubing technology such as a coiled tubing unit.
  • Core 308 and electrical conductor 316 may be elongated electrical conductors. "Elongated electrical conductors may be generally defined as electrical conductors that have a very long length as compared to their width or diameter. In some embodiments, electrical conductor 316 may extend the length of double insulated conductor 300'. In certain embodiments, as shown in FIGS. 4 and 6, core 308 and electrical conductor 316 are made of metal or another electrically conductive material. Core 308 and electrical conductor 316 may include materials such as, but not be limited to, nichrome, copper, nickel, carbon steel, stainless steel, and combinations or alloys thereof. First electrical insulator 310A and second electrical insulator 310B may be made of a variety of electrically insulating materials. For example, first electrical insulator 310A and second electrical insulator 310B may include, but not be limited to, MgO, AI2O3, Zirconia, BeO, different chemical variations of Spinels, and combinations thereof. In certain
  • first electrical insulator 310A and second electrical insulator 310B include MgO and are made from blocks of MgO.
  • Jacket 312 may be an outer metallic layer or electrically conductive layer.
  • Jacket 312 may be made of, for example, 304 stainless steel, 310 stainless steel, Incoloy® 800, and/or Inconel® 600.
  • double insulated conductor 300' is made by first forming core 308, first electrical insulator 310 A, and electrical conductor 316 into an "inner insulated conductor" (an “inner MI cable”).
  • the "inner insulated conductor” has electrical conductor 316 as its “jacket” before the addition of second electrical insulator 310B and jacket 312.
  • the "inner insulated conductor” may be formed using a milling or other MI cable forming process known in the art. For example, a process such as that disclosed in U.S. Patent No. 8,502,120 to Bass et al. may be used.
  • the "inner insulated conductor” may then be used as a "core” in a second MI cable forming process with second electrical insulator 310B and jacket 312 added to the "core” to form double insulated conductor 300' .
  • Different amounts of squeezing (compression) of the "inner insulated conductor” and the final insulated conductor (double insulated conductor 300') may be used depending on the thicknesses of first electrical insulator 310A and second electrical insulator 310B.
  • annealing temperatures may be used in the process of making the "inner insulated conductor” and the final insulated conductor.
  • lower annealing temperatures may be used to make the "inner insulated conductor” as electrical conductor 316 is the "jacket” and may be copper or another soft metal that has a lower annealing temperature than the material used in jacket 312.
  • coupling 322 is electrically coupled to core 308 and electrical conductor 316 before the addition of second electrical insulator 310B and jacket 312 and the second MI cable forming process.
  • jacket 312 may be formed around the "inner insulated conductor" with jacket 312 extending beyond coupling 322 with an open end.
  • second electrical insulator 310B may be added inside jacket 312 with some of second electrical insulator 310B extending beyond coupling 322.
  • second electrical insulator 310B may flow over the end of coupling 322 and, after end portion 312A is electrically coupled to jacket 312, the second electrical insulator may provide electrical insulation between coupling 322 and end portion 312A of jacket 312, as shown in FIG. 6.
  • double insulated conductor 300' is placed in a canister to use double insulated conductor 300' for heating the subsurface formation.
  • FIG. 7 depicts an end view representation of an embodiment of single cable double insulated conductor 300' in canister 324.
  • Canister 324 may be, for example, a carbon steel cansister.
  • Canister 324 may be used to increase heat transfer from double insulated conductor 300' to the subsurface formation.
  • double insulated conductor 300' is used in opening 302, as shown in FIG. 5, without the need for a canister.
  • double insulated conductor 300' when used as a single phase insulated conductor, may provide sufficient heat output to formation 304 without the need for the additional heat transfer provided by a canister. Using double insulated conductor 300' without the canister may decrease equipment costs associated with using double insulated conductor 300' for heating formation 304.
  • double insulated conductor 300' includes a tubular or cylindrical core instead of a solid core.
  • FIG. 8 depicts an end view representation of an embodiment of single cable double insulated conductor 300' with core 308'.
  • Core 308' may be of tubular design or a hollow core (for example, a tubular or cylindrical core with an inner opening).
  • the hollow portion of core 308' is filled with third electrical insulator 3 IOC.
  • Core 308' may be used to provide different desired heating properties (for example, different heat output properties) than core 308, shown in FIG. 4.
  • core 308 and electrical conductor 316 are dimensioned and have materials chosen to provide desired amounts of heat output from each of core 308 and electrical conductor 316.
  • core 308 and/or electrical conductor 316 may have a desired ratio of (resistive) heat output and/or desired percentages of total (resistive) heat output for double insulated conductor 300' .
  • core 308 provides at least about 50% of the total resistive heat output of double insulated conductor 300'. Electrical conductor 316 may provide the remaining resistive heat output of double insulated conductor 300'. In some embodiments, core 308 provides between about 50% and about 90% of the total resistive heat output of double insulated conductor 300' with electrical conductor 316 providing the remaining resistive heat output of between about 10% and about 50% of total resistive heat output. In some embodiments, core 308 provides between about 50% and about 80% of the total resistive heat output of double insulated conductor 300', between about 50% and about 75% of the total resistive heat output of double insulated conductor 300', or between about 50% and about 60% of the total resistive heat output of double insulated conductor 300' .
  • core 308 may include more resistive materials than electrical conductor 316.
  • core 308 may be a copper-nickel alloy while electrical conductor 316 is copper.
  • the dimensions of core 308 and/or electrical conductor 316 may be selected to provide desired percentages of heat output in core 308 and electrical conductor 316.
  • core 308 is made of different materials along a length of double insulated conductor 300' to provide different heat outputs along the length of double insulated conductor 300' .
  • a first section of core 308 may be placed adjacent to a formation layer (such as the overburden) that does not need to be heated to as high a temperature as a second formation layer (such as the hydrocarbon containing layer) that is adjacent to the second section.
  • a splice or other transition may be used to join the first section of core 308 and the second section of core 308.
  • the materials and dimensions of core 308, first electrical insulator 310A, electrical conductor 316, and second electrical insulator 310B are chosen and designed to provide desired heat output properties with selected electrical properties at a selected length for double insulated conductor 300' .
  • double insulated conductor 300' is designed to provide heat outputs of at least 250 W/ft, at least 350 W/ft, or at least 400 W/ft.
  • the desired heat output may vary depending, for example, on a time period for heat delivery and/or desired temperatures in the formation. For example, the desired heat output may be higher for initial heating of the formation to heat the formation to higher temperatures more quickly and then the heat output may be lowered to maintain a heating temperature in the formation over a long period of time without burning out the heater.
  • double insulated conductor 300' includes core 308 (Alloy 180) with an outside diameter of about 5.5 mm, first electrical insulator 310A (MgO) with an outside diameter of about 17.2 mm, electrical conductor 316 (copper) with an outside diameter of about 18.5 mm, second electrical insulator 310B (MgO) with an outside diameter of about 26.5 mm, and jacket 312 (304 stainless steel) with an outside diameter of about 28.9 mm.
  • the dimensions of core 308, first electrical insulator 310A, electrical conductor 316, second electrical insulator 31 OB, and jacket 312 may vary.
  • the outside diameter of core 308 varies between about 3 mm and about 6 mm.
  • first electrical insulator 310A may vary between about 16 mm and about 23 mm.
  • the outside diameter of electrical conductor 316 may vary between about 18 mm and about 24 mm.
  • the outside diameter of second electrical insulator 310B may vary between about 25 mm and about 29 mm.
  • the outside diameter of jacket 312 may vary between about 27 mm and about 35 mm.
  • double insulated conductor 300' of a selected outside diameter when used as a single phase insulated conductor, generates more heat than an insulated conductor operating as a three-phase insulated conductor with the same selected outside diameter.
  • double insulated conductor 300' may generate between about 10% and about 20% more heat than a similarly sized three-phase insulated conductor.
  • double insulated conductor 300' may produce the same heat output as a three-phase insulated conductor while having a smaller outside diameter (the outside diameter of double insulated conductor 300' is reduced compared to the three-phase insulated conductor).
  • double insulated conductor 300' may produce more heat output in a similar size or may produce the same heat output in a smaller size, using double insulated conductor 300' to heat a subsurface formation may be less expensive and, in some cases, simpler to install or operate than the three-phase insulated conductor.
  • double insulated conductor 300' is designed to operate at voltages above 600 volts, above 1000 volts, above 1500 volts, above 2000 volts, above 2500 volts, or above 5000 volts. Double insulated conductor 300' may operate for extended periods of time without failure at these voltages and at elevated temperatures such as over 650 °C (about 1200 °F), over 700 °C (about 1290 °F), or over 800 °C (about 1470 °F). Double insulated conductor 300' may be designed such that a maximum voltage level at a typical operating temperature does not cause substantial thermal and/or electrical breakdown of first electrical insulator 31 OA and/or second electrical insulator 310B.
  • double insulated conductor 300' is designed such that jacket 312 does not exceed an operating temperature in a wellbore (opening in the formation) that will result in a significant reduction in corrosion resistance properties of the jacket material.
  • double insulated conductor 300' may be designed to not exceed temperatures in a range between about 650 °C and about 900 °C.
  • double insulated conductor 300' may be designed to not exceed an operating temperature of about 760 °C.
  • double insulated conductor 300' is designed by providing breakdown criterion of first electrical insulator 310A and/or second electrical insulator 310B.
  • the breakdown criterion may be used along with desired heat output of double insulated conductor 300' to assess selected dimensions for double insulated conductor 300' to produce selected properties in double insulated conductor 300'.
  • dimensions for double insulated conductor 300' may be selected to minimize the electric field inside double insulated conductor 300' and/or to ensure a maximum operating temperature of double insulated conductor 300' is not exceeded.
  • the electric field profile inside double insulated conductor 300' may vary based on different geometrical dimensions of double insulated conductor 300' .
  • the example below provides an embodiment of a method for assessing breakdown criterion of first electrical insulator 31 OA and/or second electrical insulator 310B and then determining geometrical dimensions of double insulated conductor 300' based on the breakdown criterion.
  • the example below is a non-limiting example intended to describe one embodiment for determining geometrical dimensions of double insulated conductor 300' . It is to be understood that other methods may be contemplated for determining geometrical dimensions of double insulated conductor 300' .
  • dielectric strength the maximum electric field strength that a dielectric can withstand intrinsically without experiencing failure of its insulating properties. This maximum electric field strength for an electrical insulator such as MgO is the breakdown criterion.
  • FIG. 9 depicts a representation of an embodiment of an origin of the electric field in electrical insulator 310 (for example, MgO) in insulated conductor 300 with core 308.
  • electrical insulator 310 for example, MgO
  • FIG. 9 when a voltage is implemented at the inner boundary of electrical insulator 310, the electric field anywhere in electrical insulator 310 may be calculated. The electric field is not constant due to the cylindrical shape of electrical insulator 310.
  • the highest E field denoted by E pea k in EQN. 1 below is at the inner boundary of electrical insulator 310.
  • the average E denoted by E avg in EQN. 1 is inversely proportional to b-a, where a is the radius of core 308 and b is the radius of electrical insulator 310.
  • E pea k goes to infinity even with a very low voltage applied on core 308. If E pea k is used as the criterion, it means this very low voltage will break down electrical insulator 310 with a thin core 308. This may, however, not be realistic.
  • One potential solution may be to use E avg as the breakdown criterion when core 308 is very thin. Since the breakdown criterion of electrical insulator 310 (MgO) is an intrinsic property of electrical insulator 310, however, it may not be possible to use Ep e k when core 308 is big and use E avg when core 308 is small. Thus, a general breakdown criterion may be developed.
  • breakdown criterion of electrical insulator 310 is an interpolation between E pe ak and E avg . Since the dielectric strength is an intrinsic property of electrical insulator 310, one physical assumption may be that the dielectric strength does not depend on the geometrical dimension of electrical insulator 310, which means the dielectric strength for different a and b may be the same. The easiest interpolation is a linear combination given by EQN. 2:
  • Vbreak is the average first time breakdown voltage and E pe ak and E avg are analytical calculations for given a, b and Vbreak.
  • FIG. 10 depicts E pe ak, E avg and Ebreak for the chosen a in EQN. 3 from breakdown test data versus index. As shown in FIG. 10, the optimum a may be about 0.41.
  • a may still be chosen such that the variance of Ebreak is minimized.
  • This interpolation may have an advantage in the case that core 308 (Alloy 180) is very thin because Ebreak does not go to infinity when E pea k goes to infinity while E avg is finite.
  • FIG. 11 depicts a side-view representation of double insulated conductor 300'.
  • V is the voltage input on core 308
  • Ground is the ground potential
  • E2 and E 4 are the electric field in first electrical insulator 310A and second electrical insulator 310B , respectively.
  • optimized dimensions may be determined for double insulated conductor 300' (with either core 308 and/or core 308').
  • the dimensions of double insulated conductor 300' may be:
  • first electrical insulator 31 OA outside diameter 990 mil
  • FIG. 12 depicts a plot of E pe ak, E avg , and Ebreak versus different lengths of insulated conductor 300' having the above dimensions.
  • the dimensions of insulated conductor 300' may be:
  • first electrical insulator 310A outside diameter 1030 mil;
  • FIG. 13 depicts a plot of E pea k, E avg , and Ebreak versus different lengths of insulated conductor 300' having the above dimensions.
  • double insulated conductor 300' suitable for use in a subsurface formation may be selected based on the dimensions determined above for each of the different insulated conductors (the insulated conductor with core 308 or the insulated conductor with core 308' and third electrical insulator 3 IOC). In some embodiments, a criterion may be which insulated conductor can be longer given the same breakdown possibility (same E pea k or Ebreak).
  • line 326 demarcates an E pea k of 20 V/mil while line 328 demarcates an Ebreak of 15 V/mil.
  • the insulated conductor using core 308' and third electrical insulator 3 IOC may be as long as 2700 feet (based on E pe ak) or 2800 feet (based on Ebreak).
  • the insulated conductor using core 308' and third electrical insulator 310C may be about 200-300 feet longer than the insulated conductor using core 308.
  • manufacturing the insulated conductor using core 308' and third electrical insulator 3 IOC may be more costly than manufacturing the insulated conductor using core 308 and thus, any determination of which insulated conductor to use may be a balance between manufacturing cost and length of the heater as a 200-300 feet increase in heater length may not be worth extra manufacturing cost.
  • Example operation parameters for a 4000 foot long insulated conductor using core 308 are given below:
  • first electrical insulator 31 OA outside diameter 990 mil
  • electrical conductor 316 resistance 0.000736 ohm/ft
  • insulated conductor operating parameters determined above may be assessed for stability of the insulated conductor temperature and/or if the operating temperature of the insulated conductor will exceed a selected temperature. Due to leakage current in first electrical insulator 310 A, more heat may be generated in first electrical insulator 310A and this heat may reduce the resistivity of first electrical insulator 310A. Reduction in the resistivity of first electrical insulator 310A may generate even more heat inside first electrical insulator 310 A. If this effect is sufficiently amplified, the temperature of the insulated conductor may increase rapidly (blow up) starting from first electrical insulator 310A.
  • a thermal runaway simulation may be used to simulate the evolution of the temperature of the insulated conductor with time.
  • the resistivity of first electrical insulator 31 OA (MgO) may be described by EQN. 5 :
  • FIG. 14 depicts the temperature distribution along the radius r at time 100.5 s for the thermal runaway simulation.
  • the patterning region in the x-axis shows patterning corresponding to the various sections of the insulated conductor.
  • the patterning region in the x-axis corresponds to the patterning region in the inset showing a cross-sectional view of the insulated conductor.
  • the temperature of first electrical insulator 310A blows up at the time of 100.5 s and the insulated conductor temperature is above 2000 °F.
  • first electrical insulator 310A may reach a steady state temperature.
  • a higher resistivity may be used to modify EQN. 5 by a factor of 100 to EQN. 6:
  • FIG. 15 depicts the temperature distribution along the radius r at time 571 s for the thermal runaway simulation using EQN. 6. As shown in FIG. 15, the temperature of the insulated conductor reaches a steady state with the highest temperature of the insulated conductor being more than 100 °F below 1400 °F.
  • the insulated conductor is operated to deliver more heat output at the start of heating. More heat output at the start of heating may be accomplished by increasing the current through the insulated conductor. For a large range of heat delivery (for example, current varying from 150 A to 350 A), the insulated conductor may reach a steady state as shown in FIG. 15.
  • FIG. 16 depicts the temperature of core 308 (Alloy 180) and jacket 312 (304 stainless steel) versus the heat delivery rate. The current input in core 308 goes from 150 A to 350 A, which provides a heat delivery rate from 140 W/ft to 750 W/ft.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

Abstract

Cette invention concerne un dispositif de chauffage à conducteur isolé (à isolation minérale) pour chauffer une formation souterraine. Ledit dispositif de chauffage peut comprendre un premier conducteur électrique allongé, un premier isolant électrique entourant au moins partiellement le premier conducteur électrique allongé, un second conducteur électrique allongé entourant au moins partiellement le premier isolant électrique, un second isolant électrique entourant au moins partiellement le second conducteur électrique allongé, et une gaine électriquement conductrice entourant au moins partiellement le second isolant électrique. Le premier conducteur électrique allongé et le second conducteur électrique allongé peuvent être couplés électriquement à une extrémité du dispositif de chauffage à distance d'une surface de la formation. Le premier conducteur électrique allongé et le second conducteur électrique allongé peuvent fournir une sortie de chaleur résistive pour chauffer au moins une partie de la formation souterraine lorsqu'un courant électrique est appliqué au premier conducteur électrique allongé et au second conducteur électrique allongé.
PCT/US2017/044878 2016-08-08 2017-08-01 Câble isolé à isolation minérale de type coaxial, à moyenne tension, à haute puissance et à couches multiples WO2018031294A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201662371959P 2016-08-08 2016-08-08
US62/371,959 2016-08-08

Publications (1)

Publication Number Publication Date
WO2018031294A1 true WO2018031294A1 (fr) 2018-02-15

Family

ID=61162996

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2017/044878 WO2018031294A1 (fr) 2016-08-08 2017-08-01 Câble isolé à isolation minérale de type coaxial, à moyenne tension, à haute puissance et à couches multiples

Country Status (1)

Country Link
WO (1) WO2018031294A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090071652A1 (en) * 2007-04-20 2009-03-19 Vinegar Harold J In situ heat treatment from multiple layers of a tar sands formation
US20100258309A1 (en) * 2009-04-10 2010-10-14 Oluropo Rufus Ayodele Heater assisted fluid treatment of a subsurface formation
US20110247805A1 (en) * 2010-04-09 2011-10-13 De St Remey Edward Everett Insulated conductor heaters with semiconductor layers
US20110247806A1 (en) * 2010-04-09 2011-10-13 Christopher Kelvin Harris Electrodes for electrical current flow heating of subsurface formations with conductive material in wellbore

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090071652A1 (en) * 2007-04-20 2009-03-19 Vinegar Harold J In situ heat treatment from multiple layers of a tar sands formation
US20100258309A1 (en) * 2009-04-10 2010-10-14 Oluropo Rufus Ayodele Heater assisted fluid treatment of a subsurface formation
US20110247805A1 (en) * 2010-04-09 2011-10-13 De St Remey Edward Everett Insulated conductor heaters with semiconductor layers
US20110247806A1 (en) * 2010-04-09 2011-10-13 Christopher Kelvin Harris Electrodes for electrical current flow heating of subsurface formations with conductive material in wellbore

Similar Documents

Publication Publication Date Title
US8485256B2 (en) Variable thickness insulated conductors
US8939207B2 (en) Insulated conductor heaters with semiconductor layers
US8857051B2 (en) System and method for coupling lead-in conductor to insulated conductor
EP2745365B1 (fr) Épissure intégrale pour des conducteurs isolés
US9226341B2 (en) Forming insulated conductors using a final reduction step after heat treating
US20130269935A1 (en) Treating hydrocarbon formations using hybrid in situ heat treatment and steam methods
US20120085535A1 (en) Methods of heating a subsurface formation using electrically conductive particles
CA2777119C (fr) Piece de couplage a ajustement serre pour raccorder des conducteurs isoles
AU2011237479B2 (en) Insulated conductor heaters with semiconductor layers
WO2018067715A1 (fr) Dispositif de chauffage à câble isolé minéral à haute tension et à faible courant
WO2018067713A1 (fr) Connexions électriques souterraines destinées à des dispositifs de chauffage de câbles à isolant minéral à haute tension et à faible courant
WO2018031294A1 (fr) Câble isolé à isolation minérale de type coaxial, à moyenne tension, à haute puissance et à couches multiples
US20210156238A1 (en) Hinged interactive devices

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17840025

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 17840025

Country of ref document: EP

Kind code of ref document: A1