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
  • E21B7/00—Special methods or apparatus for drilling
  • E21B7/04—Directional drilling
• • 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
  • E21B19/00—Handling rods, casings, tubes or the like outside the borehole, e.g. in the derrick; Apparatus for feeding the rods or cables
  • E21B19/24—Guiding or centralising devices for drilling rods or pipes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24T—GEOTHERMAL COLLECTORS; GEOTHERMAL SYSTEMS
  • F24T10/00—Geothermal collectors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24T—GEOTHERMAL COLLECTORS; GEOTHERMAL SYSTEMS
  • F24T10/00—Geothermal collectors
  • F24T10/10—Geothermal collectors with circulation of working fluids through underground channels, the working fluids not coming into direct contact with the ground
  • F24T10/13—Geothermal collectors with circulation of working fluids through underground channels, the working fluids not coming into direct contact with the ground using tube assemblies suitable for insertion into boreholes in the ground, e.g. geothermal probes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24T—GEOTHERMAL COLLECTORS; GEOTHERMAL SYSTEMS
  • F24T10/00—Geothermal collectors
  • F24T2010/50—Component parts, details or accessories
  • F24T2010/53—Methods for installation
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/10—Geothermal energy

Definitions

• the present invention relates to a casing support and to a method for orienting and supporting a casing of a coaxial geothermal borehole heat exchanger of a geothermal energy system.
• the method also relates to a geothermal borehole heat exchanger and to a method of installing a geothermal borehole heat exchanger.
• Geothermal energy has been exploited around the globe in various forms for power generation and direct heating for more than a century. Typically these installations have been located in areas of volcanic activity where high enthalpy source rocks are located relatively close to or at the Earth's surface e.g. Western USA, Iceland or Philippines. Less well known, but of increasing importance, has been the development in recent decades of low enthalpy geothermal resources through, for example, the application of low temperature turbogenerators and through the use of ground source heat pumps (GSHP) for heating, cooling and thermal energy storage.
• GSHP ground source heat pumps
• the basic principle involved is the use of the stable thermal conditions existing in the ground formations below approximately 10 meters below surface. This stability derives from the mass of the Earth and the geothermal heat flux that originates in the molten core of the Earth. This heat flux is for all practical purposes renewable and limitless since the molten core of the Earth is sustained by nuclear decay.
• the ground formations can supply, absorb or store large quantities of thermal energy by means of tubular heat exchangers inserted into the ground and coupled to a heat pump (single-acting or reversible configuration) at surface utilising a working fluid as the heat transfer medium.
• BHE borehole heat exchangers
• HP heat pump
• this is a tube-in-tube arrangement
• an outer cylindrical casing that is used to line and support the borehole wall and within which is installed a matching tubing of smaller diameter that is suspended so as to locate its open end a short distance above the bottom of the borehole.
• the inner tube is centralised in the bore of the outer casing so as to facilitate optimisation of the thermal and hydraulic flows in the BHE.
• the closed loop is then formed by water circulation either down the inner tube and back up the annulus between the inner tube and outer casing or the reverse depending upon the design considerations.
• the heat transfer is by conduction to the flow of water in the annulus and the efficiency benefits from the larger effective contact area of the water with the ground formations offered by the outer casing, providing the hydraulic conditions are optimised.
• a surface collector system is provided for the BHE installation to gather or distribute thermal energy to or from substantial buildings.
• Such a surface collector system may consist of up to 100% extra length of pipe in addition to the total vertical pipe length provided for the in- ground heat transfer process.
• This additional surface piping causes constant operating losses, such as thermal energy and pressure losses. This in turn requires additional electrical energy for compensation of the operating losses, as well as an increased cost for construction and maintenance of the extensive surface collector systems. This has, for a long time, been a limiting factor for large GSHP installations.
• FIG. 1 there is shown a sectional view of a known installation of a coaxial geothermal borehole heat exchanger (BHE).
• BHE coaxial geothermal borehole heat exchanger
• Figure 1 shows the assembly during installation and Figure 2 shows a BHE and well head after installation.
• Figure 1 has an inclined a vertical BHE orientation and
• Figure 2 has a vertical BHE orientation.
• One or multiple BHE's are typically installed in an inspection chamber 4 pre-set within the ground 2 and below ground level prior to the drilling operation commencing.
• the chamber 4 includes a concrete base 6 and a sidewall 8 extending upwardly therefrom.
• the sidewall 8 may comprise a stack of concrete tubes and may, as shown, include internal access steps 24 within the chamber 4.
• the borehole heat exchanger is installed, at a selected angle, through the concrete base 6.
• the coaxial geothermal borehole heat exchanger (BHE)
• BHE coaxial geothermal borehole heat exchanger
• This temporary casing 12 is designed to be retrieved and reused to reduce costs or it can be left in place depending on time it takes to retrieve and the length used.
• the length of temporary casing 12 is between 5 and 30 meters, although it may be longer or shorter.
• the coaxial geothermal borehole heat exchanger (BHE) 14 extends downwardly through the temporary casing 12 to the bottom of the drilled borehole.
• each BHE 14 is connected at its upper end to a well head 16.
• the well head 16 has fittings to connect to a conduit or fluid flow line 22 connecting to the heat exchanger (not shown) of the geothermal energy system.
• the chamber 4 is closed with a lid 20 located at its upper end above the sidewall 8.
• the lid 20 may have a central hole for permitting downward passage there through of lengths of BHE 18 during installation.
• This known installation procedure adds installation costs due to the time it takes to land the casing and the cost of the shorter outer casing lengths. Furthermore, this known installation procedure does not eliminate the result that variable lengths of BHE can be installed, the length varying between different BHEs within a common geothermal system, which in turn leads to variable flow in each BHE of the heat exchange fluid caused by the varying pressure loss in each BHE.
• the variation in flow in each BHE can lead to inconsistent BHE performance and can only be eliminated by individually choking flow to each BHE to balance the flow to each BHE. This adds costs both in installation time and equipment.
• the inconsistent setting depth of the casing 12 also means that each well head 16 can be at varying heights within the chamber 4. This results in the problem that each connection to the borehole flow line 22 will vary, requiring customisation on site.
• the present invention aims at least partially to overcome these problems of known installations and casing structures of coaxial geothermal borehole heat exchangers.
• the present invention provides a geothermal borehole heat exchanger supported in a borehole by a casing support, the casing support being fitted around an outer casing of the geothermal borehole heat exchanger and suspending the borehole heat exchanger within a borehole extending downwardly from the casing support, the casing support defining a predetermined angle of an upper end of the borehole heat exchanger within the borehole.
• the present invention further provides a chamber comprising a plurality of geothermal borehole heat exchangers according to the invention, each casing support having a respective borehole heat exchanger extending downwardly therefrom at a respective orientation.
• the present invention further provides a method of installing a geothermal borehole heat exchanger, the method including the steps of:
• the present invention further provides a casing support of a geothermal borehole heat exchanger having an outer casing, the casing support comprising a base support element incorporating an aperture therethrough, the base support element being arranged to be supported by a ground surface around a borehole, an annular orientation guide element at an upper surface of the base support element and having a central conduit communicating with the aperture, the orientation guide element having an upper surface at a selected angle relative to a lower support surface of the base support element, and a casing support ring fitted around an outer casing of a geothermal borehole heat exchanger, the casing support ring being coupled to the orientation guide element to support the casing in the borehole, the outer casing extending through the ring, the conduit and the aperture.
• the present invention further provides a chamber comprising a plurality of casing supports according to the invention, each casing support having a respective borehole heat exchanger extending downwardly therefrom at a respective orientation.
• the present invention further provides a method of installing a casing support of a geothermal borehole heat exchanger having an outer casing, the method including the steps of:
• the preferred embodiments of the present invention can provide a low cost modular system to enable the outer casing of a coaxial geothermal BHE to be supported from an upper surface, in particular a chamber surface.
• the coaxial geothermal BHE may in particular being suspended or hung from the bottom wall of the chamber rather than supported by the base of the borehole.
• the preferred embodiments of the present invention can also provide that the base of the borehole chamber may be sealed.
• the preferred embodiments of the present invention can further provide that the orientation of the borehole and inclination of the borehole is predetermined, which can eliminate the possibility of human error during set up of the drilling process.
• the modular system of the preferred embodiments of the present invention also allows ease of manufacturing and installation, since a common set of components can be used for various borehole depths and/or inclinations.
• FIG 1 is a schematic sectional view of a known installation of a coaxial geothermal borehole heat exchanger (BHE), illustrated during installation;
• BHE coaxial geothermal borehole heat exchanger
• Figure 2 is a schematic sectional view of the installation of Figure 1 after installation of the well head;
• FIG. 3 is a schematic sectional view of an installation of a coaxial geothermal borehole heat exchanger (BHE), illustrated during installation, in accordance with a first embodiment of the present invention
• FIG. 4 is a schematic sectional view of an installation of a coaxial geothermal borehole heat exchanger (BHE), illustrated during installation, in accordance with a second embodiment of the present invention
• Figure 5 is a schematic exploded sectional view perspective view of chamber components of the installations of Figures 1 and 2;
• Figure 6 is a schematic section through an orientation guide of the installation of Figure 1 ;
• Figure 7 is a schematic section through an orientation guide of the installation of Figures 2;
• Figure 8 is a schematic sectional view of a modified structure of the installation of Figure 3, illustrated after installation of the well head;
• Figure 9 is a schematic sectional view of a modified structure of the installation of Figure 4, illustrated after installation of the well head;
• Figure 10 is a schematic sectional view of the installation of Figure 4, illustrated during installation of the orientation guide.
• Figure 1 1 is a schematic section through an alternative base support element incorporating plural integral orientation guides according to another embodiment of the invention.
• FIGS 3 and 4 there are shown schematically an installation system of a borehole heat exchanger of a geothermal energy system in accordance with first and second embodiments of the present invention.
• Figures 3 and 4 show the assembly during installation.
• the embodiment of Figure 3 has a vertical BHE orientation and the embodiment of Figure 4 has an inclined BHE orientation.
• a BHE is installed in an inspection chamber pre-set within the ground (not shown) and below ground level prior to the drilling operation commencing.
• the chamber includes a base support element 30 in the form of a plate.
• the base support element 30 is typically composed of pre-cast concrete.
• the base support element 30 has an aperture 36 extending therethrough.
• the base support element 30 has standard dimensions for all borehole inclinations.
• the reinforced concrete or other material can support up to 15 tons of weight suspended through the aperture 36.
• a sidewall 32 extends upwardly from the base support element 30.
• the sidewall 32 may comprise a stack of concrete tubes and may, as shown, include internal access steps within the chamber.
• a lid 34 having an access opening 35 is located on the sidewall 32.
• the lid 34, sidewall 32 and base support element 30 are shown in exploded form in Figure 5.
• the borehole heat exchanger is installed, at a selected angle, through the base support element 30, as described hereinafter.
• annular orientation guide element 38, 58 is fitted onto an upper surface 40 of the base support element 30.
• the orientation guide element 38, 58 is separate from but fitted to the base support element 30.
• the orientation guide element 38, 58 is at the upper surface 40 of the base support element 30, and in alternative embodiments the base support element 30 and the orientation guide element 38, 58 are integral, for example the base support element 30 and the orientation guide element 38, 58 being composed of a single body of precast concrete.
• the single body may include plural orientation guide units, at respective positions and inclinations to the vertical.
• Figure 1 1 shows such a structure, with a base support element 130 and integral orientation guide elements 138, 158, which are a single body, for example of precast concrete. Although two integral orientation guide elements are provided in the single body, any number may be present and formed together with the base support element, and any orientations or combinations of orientations may be provided.
• the orientation guide element 38, 58 has a central conduit 52, 60 communicating with the aperture 36.
• the orientation guide element 38, 58 has an upper surface 39, 59 at a selected angle relative to a lower support surface 37, 57 of the base support element 30.
• the base support element 30 and the orientation guide element 38, 58 are provided with interlocking elements 48, 50 which mutually fit together to locate the orientation guide element 38, 58 at a preset rotational position, with respect to a longitudinal axis of the aperture 36, relative to the base support element 30.
• the interlocking elements 48, 50 comprise male and female elements.
• the interlocking elements 48, 50 ensure a fail-safe alignment between the base support element 30 and the orientation guide element 38, 58.
• the upper surface 39, 59 of the orientation guide element 38, 58 is parallel to, or inclined at an angle to, a lower surface 41, 61 of the orientation guide element 38, 58.
• the upper and lower surfaces of the orientation guide element 38 are parallel whereas in the embodiment of Figures 4 and 7 the upper and lower surfaces of the orientation guide element 58 are mutually inclined at an acute angle, in this embodiment 15 degrees.
• the upper and lower surfaces of the orientation guide element 58 may typically be mutually inclined at any desired angle of from 5 to 45 degrees.
• the orientation guide element 38, 58 is typically composed of pre-cast concrete and has a standard selected borehole inclination, for example zero, 5, 10 or 15 degrees.
• the reinforced concrete or other material can support up to 15 tons of weight suspended through the aperture 36.
• a casing support ring 54 is fitted around the upper end 44 of an outer casing 46 of a geothermal borehole heat exchanger.
• the casing support ring 54 is coupled to the orientation guide element 38, 58 to support the casing 46 in the borehole.
• the outer casing 46 extends through the ring 54, the conduit 52, 60 and the aperture 36.
• the casing support ring 54 has an inner annular surface engaging an outer cylindrical surface of an upper end 44 of the outer casing 46.
• the inner annular surface o the casing support ring 54 threadably engages the outer cylindrical surface of the upper end 44 of the outer casing 46.
• This assembly orients the outer casing 46 at the desired vertical or off-vertical orientation, shown by axes B and C in Figures 3 and 4.
• the chamber has vertical axis A.
• the casing support ring 54 comprises an inner element 68 mounted around the upper end 72 of the coaxial borehole heat exchanger 80 and an outer landing guide 62 mounted on the orientation guide element 58.
• Figure 10 shows the arrangement during installation. After installation, the inner element 68 is fitted in the outer landing guide 62.
• the inner element 68 and the landing guide 62 have complementary outer and inner conically tapered fitting surfaces 70, 64 to permit the inner element 68 to be downwardly fitted into a conduit 66 of the landing guide 62.
• a borehole surface casing 42 surrounds an upper portion of the outer casing 46 of the borehole heat exchanger within the borehole and is fitted to the casing support ring 54, in particular to the outer landing guide 62 of the casing support ring 54.
• the borehole surface casing 42 is threadably fitted to an inner annular surface of a downwardly extending flange 75 of the landing guide 62.
• the base support element 30 incorporating the aperture 36 therethrough is provided so as to be supported by a ground surface, preferably in a below- ground chamber.
• the annular orientation guide element 38, 58 is fitted onto the upper surface of the base support element 30, the orientation guide element 38, 58 having a central conduit 52, 60 communicating with the aperture 36.
• the orientation guide element 38, 58 has an upper surface at a selected angle relative to a lower support surface of the base support element 30.
• a casing support ring 54 is installed so as to be coupled to the orientation guide element 38, 58.
• a borehole surface casing 42 is fitted to surround an upper portion of the borehole and fitted to the casing support ring 54.
• a borehole is drilled through the central conduit 52, 60 and the aperture 36 at an orientation preset by the orientation guide element 38, 58.
• the borehole heat exchanger is fitted into the borehole and the casing support ring 54 is fitted around the outer casing 46 of the geothermal borehole heat exchanger and supports the outer casing 46 in the borehole, the outer casing extending through the ring 54, the conduit 52, 60 and the aperture 36.
• the casing support ring 54 is installed at the top of the surface casing 42 if the surface casing 42 is not be retrieved after installation.
• the surface casing 42 is a drilling conductor length of surface casing 42 which is present during drilling and grouting operations to transfer drilling fluids and drilled cuttings to the surface for processing.
• the upper end 72 of the coaxial borehole heat exchanger 80 may comprise an additional short joint of casing, typically 50cm in length, for running and installing the inner element 68 in the outer landing guide 62.
• the well head 60 is then attached to the short joint of casing.
• casing support ring 54 comprises the landing guide 62 which is directly fitted, for example by a threaded coupling, to the upper portion 44 of the outer casing 46 of the borehole heat exchanger. In these embodiments, the surface casing 42 is to be retrieved.
• the casing support ring 54 is installed directly onto the outer casing 46.
• the casing support ring 54 has a first annular thread for temporarily supporting the borehole surface casing 42 and a second annular thread fitting to the outer casing 46.
• the casing support ring 54 sits on the orientation guide element 38, 58 and transfers the weight of the outer casing 46 to the orientation guide element 38, 58 and then to the base support element 30, the ultimate load bearing support for the outer casing 46 of the BHE.
• the borehole heat exchanger 46 extends downwardly to a depth of greater than 100 metres, optionally from 100 to 200 metres.
• a wellhead 60 is fitted to the upper end of the borehole heat exchanger 46 and coupled to flow lines 56 of the geothermal system.
• Each casing support has a respective borehole heat exchanger 46 extending downwardly therefrom at a respective orientation.
• the orientations of at least some of the borehole heat exchangers 46 are different, each orientation being provided by a corresponding selected orientation of the respective orientation guide element 38, 58.
• the BHEs may have different orientations.
• the use of multiple boreholes in a single chamber reduces the surface area of the ground required for the boreholes.
• the area of contact between the orientation guide element 38, 58 and base support element 30, and between the casing support ring 54 and the orientation guide element 38, 58 are sealed using a sealing compound. This ensures that surface water coming up from the borehole cannot enter the chamber, thereby protecting the well head and associated connections and flow lines against corrosion.
• a sealing compound This ensures that surface water coming up from the borehole cannot enter the chamber, thereby protecting the well head and associated connections and flow lines against corrosion.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Mining & Mineral Resources (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Fluid Mechanics (AREA)
• Environmental & Geological Engineering (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• General Engineering & Computer Science (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
• Geophysics And Detection Of Objects (AREA)

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• 2011
  • 2011-11-11 GB GB1119470.1A patent/GB2491664B/en active Active
• 2012
  • 2012-09-07 GB GB1218685.4A patent/GB2491794B/en active Active
  • 2012-09-07 GB GB1215986.9A patent/GB2491746B/en active Active
  • 2012-11-09 CA CA2854841A patent/CA2854841A1/en not_active Abandoned
  • 2012-11-09 EP EP12786974.1A patent/EP2776766A2/en not_active Withdrawn
  • 2012-11-09 WO PCT/EP2012/072332 patent/WO2013068570A2/en active Application Filing
  • 2012-11-09 KR KR20147015903A patent/KR20140127799A/ko not_active Application Discontinuation
  • 2012-11-09 CN CN201280066859.1A patent/CN104040270A/zh active Pending
  • 2012-11-09 JP JP2014540493A patent/JP2014533332A/ja active Pending
  • 2012-11-09 US US14/356,593 patent/US20140299291A1/en not_active Abandoned

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