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(11) | EP 4 800 321 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A PRESSURE SENSITIVE ELEMENT AND A GEOTHERMAL PIPING SYSTEM |
| (57) Disclosed herein is a pressure sensitive element (2, 2', 2a, 2b, 2a', 2b') for geothermal
applications, comprising: - a shell (4, 4', 4a, 4b, 4a', 4b') enclosing a three-dimensional space, the shell (4, 4', 4a, 4b, 4a', 4b') comprising a wall (6a, 6b, 6a', 6b') having a wall thickness, the wall being made of temperature resistant and elastic material, and - a compressible and/or expandable, pressure-sensitive fluid arranged within the shell (4, 4', 4a, 4b, 4a', 4b'). The shell (4, 4', 4a, 4b, 4a', 4b') is designed to allow expansion or contraction in a first direction (A) upon external pressure change, as seen on a cross sectional plane cut through the shell (4, 4', 4a, 4b, 4a', 4b'). The cross sectional plane is parallel with the first direction (A) and wherein the first direction (A) is determined by a wall thickness of the shell (4, 4', 4a, 4b, 4a', 4b'), which is chosen to be smaller than the wall thickness of the shell (4, 4', 4a, 4b, 4a', 4b') in other parts, at least along a partial length (L) of the wall (6a, 6b, 6a', 6b') in the cross sectional plane. |
Technical field
[0001] The present disclosure relates to, in a first aspect, pressure sensitive elements that can be used among other fields in geothermal applications. The pressure sensitive elements are designed to be robust and without mechanical or electronic parts in order to withstand tough conditions in boreholes. In a second aspect the disclosure relates to a geothermal piping system that uses the pressure sensitive elements to support a supply pipe on its way into the borehole.
Technical background
[0002] Geothermal energy production often requires drilling deep boreholes that penetrate into geologically complex and hostile environments. At these depths, temperatures can be extremely high and humidity levels can be significant due to the presence of geothermal fluids such as for example steam. Equipment placed in such deep boreholes is also exposed to various hazards, such as sudden rock impacts caused by shifts or collapses in the borehole walls, as well as contact with chemically aggressive fluids that may exit from fissures or other formations. These combined factors can degrade, corrode, or physically damage conventional equipment - particularly where sensitive mechanical or electrical components are involved.
[0003] In many geothermal applications, specialized downhole devices must perform tasks automatically. Traditional approaches to these tasks commonly rely on complex assemblies-such as electric motors, hydraulic elements, and electronic controls - which are prone to malfunction or breakdown under severe conditions of temperature, pressure, and chemical exposure.
[0004] Accordingly, there is an ongoing need for simplified, robust, and reliable solutions that can withstand the environmental extremes present in deep geothermal boreholes. Devices that operate without mechanical linkages, electric motors, or delicate sensor systems offer the potential to reduce the risk of failure. In particular, systems that employ inherent material properties or direct fluid-pressure-responsive structures can achieve certain functions-such as friction generation or flow regulation - without relying on external power or electronic con§trol signals. By minimizing the complexity of the downhole devices or elements, operators can improve the reliability of geothermal systems, reduce maintenance requirements, and enhance overall operational safety and efficiency.
Summary
[0005] In view of the above it is an object of the present disclosure to provide a pressure sensitive element that is robust, reliable and has a high durability.
[0006] It is a further object of the present disclosure to provide a geothermal piping system comprising at least one pressure sensitive element, wherein the geothermal piping system is durable and robust.
[0007] Disclosed herein is a pressure-sensitive element for geothermal applications. In one aspect, a shell encloses a three-dimensional space and is formed of a temperature-resistant, elastic material. Within the shell, a compressible pressure-sensitive fluid is arranged. The shell is designed so that, when viewed in a cross-sectional plane, it allows expansion or contraction in a first direction upon external or surrounding pressure change. This first direction is determined by providing a region of smaller wall thickness-at least along a partial length of the wall in the cross-sectional plane-relative to other areas of the shell's wall.
[0008] The above provides for a pressure sensitive element that can expand and contract along the first direction depending on the surrounding pressure, due to the smart design with specific wall thickness and the use of a pressure-sensitive fluid.
[0009] In a further aspect, the partial length of the wall with the smaller thickness can be oriented parallel to the above-mentioned first direction.
[0011] In another variation, the shell may be partially or entirely formed of Teflon, rubber, polymer, carbon, graphene, or Kevlar, or any combination thereof.
[0012] Additionally, the fluid contained within the shell can be selected from, for example, air, natural gas, various gases, hydraulic oil, heavy oil, lubricating oil, hydrogen, oxygen, or helium.
[0013] In another embodiment, the pressure-sensitive element has a toroidal geometry, thereby functioning as a pressure-sensitive sealing. The toroidal shape defines a toroidal plane.
[0014] If the pressure sensitive elements are designed as sealings or O-rings many potential applications may come to mind, where such pressure sensitive O-rings may be used.
[0015] One configuration of the toroidal shape comprises a shell wall that is thinner on its top and bottom peripheries than in other regions (such as an inner or outer periphery), enabling expansion in a first direction parallel to the toroidal plane.
[0016] Another configuration of the toroidal shape comprises a shell wall that is thinner on its inner and outer peripheries than on the top and bottom peripheries, thereby allowing expansion in a first direction, perpendicular to the toroidal plane.
[0017] In some examples, this toroidal shell may function as an O-ring or sealing component; in other variations, it may be shaped like a pipe section and used for sealing purposes.
[0018] The above may enable various applications such as controlling of fluid flow in a pipe, when the O-rings are arranged within the pipe, and/or even connecting components depending on present pressure. Another application may be to embrace or hug a pipe, when arranged on an outer side of the pipe for holding or bearing purposes depending on pressure.
[0019] This disclosure also encompasses a geothermal piping system comprising a supply pipe for delivering a liquid into a borehole, at least one retainer - shaped as a ring or an elliptical ring and designed to fit within the borehole, whereby the retainer includes a cutout that is designed to receive the supply pipe. A pressure-sensitive element, shaped as a torus or a pipe segment, as described above, is arranged around the supply pipe so that it protrudes beyond the cutout, thereby bearing at least a part of the weight of the supply pipe. Because the element "embraces" the supply pipe by expanding in a cross-sectional plane, thereby creating friction on the supply pipe, it provides frictional retention that is responsive to downhole pressure conditions. Multiple such retainers and pressure-sensitive elements may be spaced at regular intervals along the depth of the borehole to ensure stable support and bearing of the supply pipe.
[0020] Such a geothermal piping system allows to generate friction depending on the surrounding pressure. Under high-pressure conditions, for instance, when superheated steam is generated, these pressure sensitive elements can expand to grip and hold the supply pipe securely. Conversely, if the steam or pressure is not present, the pressure sensitive elements may relax and release the supply pipe.
[0021] The above described automatic pressure-based actuation avoids sealings, or O-rings or general shapes that require electronic or mechanical controls. It also reduces the reliance on delicate mechanical or electrical components, thereby enhancing reliability in harsh geothermal environments.
[0022] In this disclosure certain terms and expression are used, which are herewith briefly explained:
Pressure sensitive element, acutator or sealing
[0023] The term "pressure sensitive element", pressure sensitive actuator or pressure sensitive sealing refers to a device designed to change its shape depending on changes in pressure. These pressure sensitive elements typically comprises a shell enclosing a three-dimensional space and a compressible, pressure-sensitive fluid within the shell. The shell may have any form of three-dimensional shape that is useful. The element is characterized by its ability to expand in a specific direction when subjected to pressure changes, depending on design choices, in particular specific wall thickness variations in the shell. Broadly, pressure sensitive elements can be used in various applications where pressure changes need to be converted into mechanical movement or force. In a narrower sense, the pressure sensitive elements described in here are specifically designed for geothermal applications, where it may function as a sealing, a control element or support mechanism within a geothermal piping system.
Shell
[0024] The term "shell" describes a structural component of the pressure sensitive element that encloses a three-dimensional space. It is made of temperature-resistant and elastic material, allowing it to withstand the harsh conditions typically found in geothermal environments. The shell's design includes a wall with varying thickness, which is basically determining the direction of the expansion of the element in a predetermined direction. In a broad sense, a shell can be any enclosing three-dimensional structure that provides protection and containment. In this specific application, the shell's wall thickness is strategically varied to facilitate expansion in a desired direction, enhancing the element's functionality. The shell may be made of Teflon, rubber, polymer, carbon, graphene, or Kevlar, or any combination of these materials.
Pressure-Sensitive Fluid
[0025] The term "pressure-sensitive fluid" is a compressible medium contained within the shell of the element. This fluid responds to pressure changes by compressing or expanding, thereby enabling the presssure sensitive element to perform its function. Generally, pressure-sensitive fluids can include gases or liquids that are capable of undergoing volume changes under pressure. In the context of this disclosure, the fluid could be air, natural gas, hydraulic oil or other specific oils such as lubricating oil or heavy oils or other suitable substances that provide the necessary compressibility and responsiveness to pressure variations.
Wall Thickness
[0026] "Wall thickness" refers to the measurement of the shell's wall from its inner to its outer surface, typically as seen in a cross sectional plane. This parameter is determining the direction and extent of the element's and the shell's expansion and contraction, respectively. In a broad sense, wall thickness can affect the strength, flexibility, and thermal properties of a structure. In the specific context of the element, the wall thickness is varied along different sections of the shell to control the expansion and compression direction, ensuring that the element functions effectively under pressure.
Toroidal Geometry
[0027] The term "toroidal geometry" describes the shape of the shell, which is similar to a torus or doughnut shape. This geometry is particularly useful in applications where a circular or ring-like structure is needed, such as in seals or O-rings. Broadly, toroidal shapes are used in various engineering applications for their ability to provide uniform pressure distribution and sealing capabilities. In the claims, the toroidal geometry is specifically adapted for use in geothermal applications, where it may serve as a pressure-sensitive sealing mechanism. The term toroidal geometry used herein covers ring-shapes, pipe-section shapes, torus-shapes and doughnut-shapes and combinations thereof.
Geothermal Piping System
[0028] A geothermal piping system is an assembly of at least one pipe and potentially components designed to transport fluids into and out of a geothermal borehole. The geothermal piping system typically includes supply pipes, retainers, and pressure-sensitive elements to ensure efficient and safe operation. In a broad sense, geothermal piping systems are used to harness geothermal energy by circulating fluids into a borehole. The specific system described in the claims incorporates a pressure-sensitive element to support and stabilize the supply pipe within the borehole, highlighting its role in maintaining the integrity and functionality of the geothermal installation.
Brief Description of the Drawings
[0029] The disclosure will be described in more detail in the following, by way of example and with reference to the appended drawings, in which
- Figure 1:
- schematically illustrates a pressure sensitive element in the form of an O-ring;
- Figure 2:
- schematically illustrates a pressure sensitive element in the form of a pipe section or ring;
- Figure 3a:
- schematically illustrates a cross-sectional view onto a first embodiment according to figure 1, cut along line III-III;
- Figure 3b:
- schematically illustrates a cross-sectional view onto a second embodiment according to figure 1, cut along line III-III;
- Figure 4a:
- schematically illustrates a cross-sectional view onto a first embodiment according to figure 2, cut along line VI-VI;
- Figure 4b:
- schematically illustrates a cross-sectional view onto a second embodiment according to figure 2, cut along line VI-VI;
- Figure 5:
- schematically illustrates a retainer designed to a be used in a borehole, and
- Figure 6:
- schematically illustrates a geothermal piping system using the pressure sensitive elements according to the disclosure.
Detailed Description
[0030] Figure 1 illustrates a pressure sensitive element 2, 2a, 2b in the form of an O-ring or sealing. The pressure sensitive element 2, 2a, 2b comprises a shell 4, 4a, 4b made of a flexible and elastic material. The shell 4, 4a, 4b may also be made of a temperature resistant material. In figure 1, a plane III - III is illustrated, which indicates a cross-sectional cut through the pressure sensitive element 2, 2a, 2b and its shell 4, 4a, 4b, respectively, as indicated in figures 3a and 3b.
[0031] Figure 2 illustrates an alternative embodiment of the pressure sensitive element 2', 2a', 2b' in the form of a sealing, which is pipe-section shaped or ring shaped. The pressure sensitive element 2', 2a', 2b' also comprises a shell 4', 4a', 4b' and a plan IV - IV, is illustrated which indicates a cross-sectional cut through the pressure sensitive element 2', 2a', 2b' and the shell 4', 4a', 4b', respectively, as indicated in figures 4a and 4b.
[0032] Turning now to figures 3a and 3b, cross sectional views of two different embodiments of the sealing 2, 2a, 2b or O-ring of figure 1 is illustrated. The arrows A illustrate an expansion and contraction direction based on the hereinafter described designs. The shells 4a, 4a' illustrated in figures 3a and 3b may be filled with a pressure sensitive fluid or liquid, which typically expands or contracts depending on surrounding pressure.
[0033] Figure 3a illustrates a cross-sectional view of a pressure sensitive element 2a having a shell 4a with walls 6a. The pressure sensitive element 2a comprises a top periphery 8a and a bottom periphery 8a'. Further, the pressure sensitive element 2a also comprises an inner periphery 10a' and an outer periphery 10a. As can be seen from figure 3a along a partial length L of the wall 6a, at least more or less parallel with the bottom periphery 8a and the top periphery 8b, a thickness of the wall 6a is reduced compared with the wall thickness along the inner - and outer periphery 10a', 10a. This leads to an expansion and contraction of the pressure sensitive element or sealing 2a along the arrows A depending on surrounding pressure changes. Studying figure 3a it also becomes clear for the skilled person that the thickness of the wall 6a that is smaller than the rest of the wall can be further varied to provide sealings, O-rings or pressure sensitive elements that can interact with one another along various pressure ranges and/or pressure change ranges.
[0034] Figure 3a further illustrates a central axis Z of the toroidal shape 4a, which toroidal shape 4a has a toroidal plane defined by the central axis Z. The central axis Z defines a circle and therewith defines the toroidal plane, also together with a centre of the toroidal shape 4a. It is to be noted that all embodiments in figures 1 to 4b and figure 6 of the pressure sensitive elements 2, 2', 2a, 2b, 2a', 2b' have and define such central axis Z, which are similar or the same as illustrated in figure 3a, however for the sake of simplicity the central axis Z and therewith the toroidal plane is only illustrated in figure 3a.
[0035] Figure 3b illustrates another embodiment of a pressure sensitive element 2b according to figure 1, in a cross-sectional view, the pressure sensitive element 2b having a shell 4b with walls 6a. The pressure sensitive element 2b comprises a top periphery 8b and a bottom periphery 8b'. Further, the pressure sensitive element 2b also comprises an inner periphery 10b' and an outer periphery 10b. As can be seen from figure 3b along a partial length of the wall 6b, at least more or less parallel with the inner periphery 10b' and the outer periphery 10b, a thickness of the wall 6b is reduced compared with the wall thickness along the top - and bottom periphery 8b, 8b'. This leads to an expansion and contraction of the pressure sensitive element or sealing 2b along the arrows A depending on surrounding pressure changes. Studying figure 3b it also becomes clear for the skilled person that the thickness of the wall 6b that is smaller than the rest of the wall can be further varied to provide sealings, O-rings or pressure sensitive elements than can interact with one another along various pressure ranges and/or pressure change ranges.
[0036] Figure 4a illustrates a cross-sectional view of a pressure sensitive element 2a' having a shell 4a' with walls 6a'. The pressure sensitive element 2a' comprises a top periphery 13a and a bottom periphery 13b (c.f. figure 4b). Further, the pressure sensitive element 2a' also comprises an inner periphery 12b and an outer periphery 12a. As can be seen from figure 4a along a partial length L of the wall 6a', at least more or less parallel with the inner periphery 12b and the outer periphery 12a, a thickness of the wall 6a' is reduced compared with the wall thickness along the inner - and outer periphery 12b, 12a. This leads to an expansion and contraction of the pressure sensitive element or sealing 2a' along the arrows A depending on surrounding pressure changes. Studying figure 4a it also becomes clear for the skilled person that the thickness of the wall 6a' that is smaller than the rest of the wall 6a' can be further varied to provide sealings, O-rings or pressure sensitive elements 2a' than can interact with one another along various pressure ranges and/or pressure change ranges.
[0037] Figure 4b illustrates another embodiment of a pressure sensitive element 2b' according to figure 2, in a cross-sectional view, the pressure sensitive element 2b' having a shell 4b' with walls 6b'. The pressure sensitive element 2b' comprises a top periphery 13a and a bottom periphery 13b. Further, the pressure sensitive element 2b' also comprises an inner periphery 10b' and an outer periphery 10b (c.f. figure 4a). As can be seen from figure 4b along a partial length L of the wall 6b', at least more or less parallel with the top periphery 13a and the bottom periphery 13b, a thickness of the wall 6b' is reduced compared with the wall thickness along or on the inner - and outer periphery. This leads to an expansion and contraction of the pressure sensitive element or sealing 2b' along the arrows A depending on surrounding pressure changes. Studying figure 4b it also becomes clear for the skilled person that the thickness of the wall 6b' that is smaller than the rest of the wall can be further varied to provide sealings, O-rings or pressure sensitive elements than can interact with one another along various pressure ranges and/or pressure change ranges. Further, in figure 4b the borehole 14 (or a supply pipe for that matter) is also indicated and from the figure 4b it becomes clear that the pressure sensitive element 2b' can regulate fluid flow within the borehole 14 or supply pipe by increasing or decreasing the cross-sectional area available for the fluid flow depending on decreasing or increasing pressure.
[0038] In general, the arrows A in figures 3a to 4b illustrate a first direction A, along which the pressure sensitive elements 2, 2', 2a, 2b, 2a', 2b' can expand and contract depending on pressure changes.
[0039] Further, figures 3a and 4a also schematically indicate where the pressure sensitive fluid 3 or liquid is arranged within the shells 4a, 4a'.
[0040] In all figures 3a to 4b, the length L, along which the wall 6a, 6b, 6a', 6b' or thickness of the wall is thinner than in other places of the shell 4a, 4b, 4a', 4b', is indicated. It is clear to the skilled person that thin wall part extends along the periphery where it is arranged around the toroidal-, ring-, O-ring, or pipe-section shape. Further it is also clear that the value of the length L can vary in each embodiment. Finally, the expansion or contraction of the pressure sensitive element 2, 2', 2a, 2b, 2a', 2b' follows typically the same direction as the thinner part of the wall 6a, 6b, 6a', 6b'.
[0041] Turning now to figure 5, a retainer 16 having a recess 18 is shown. The retainer is generally round or elliptic and shaped as a ring, typically made of a flexible material, for example, plastic, fibre-reinforced plastic, carbon or elastic steel. In the example in figure 5, the retainer 16 is arranged within a borehole 14 and keeps a supply pipe 20 steady in position in the borehole 14. Due to its shape, the retainer 16 is releasably arranged, since inclining or twisting it out of a plane as shown in figure 5 will result in its release.
[0042] Now figure 6, illustrates a geothermal piping system 22 and how, at least some of the embodiments of the pressure sensitive elements 2, 2', 2a, 2b' according to the previously described embodiments, may be used to suspend and bear the supply pipe 20 in a borehole 14. The recesses 18 or cut outs of the retainer 18 are designed so that pressure sensitive elements (O-rings) cannot pass through them, at least under certain pressure conditions, so that they embrace the supply pipe 20 and create friction due to expansion in a direction perpendicular to the longitudinal direction of the borehole 14. This allows to employ an automatic bearing of the supply pipe 20 at regular intervals, which is needed for deep boreholes, such as boreholes with several thousand meters of depth.
[0043] In light of the above, it can be understood that the inventive concept according to this disclosure allows for various applications, not only geothermal ones, where automatic functions the use of electronics or complex mechanical solutions are needed. The skilled person understands that several applications for the disclosed sealings, O-rings or pressure sensitive elements do exist.
1. A pressure sensitive element (2, 2', 2a, 2b, 2a', 2b') for geothermal applications,
comprising:
- a shell (4, 4', 4a, 4b, 4a', 4b') enclosing a three-dimensional space, the shell (4, 4', 4a, 4b, 4a', 4b') comprising a wall (6a, 6b, 6a', 6b') having a wall thickness, the wall being made of temperature resistant and elastic material;
- a compressible and/or expandable, pressure-sensitive fluid arranged within the shell (4, 4', 4a, 4b, 4a', 4b');
characterized in that the shell (4, 4', 4a, 4b, 4a', 4b') is designed to allow expansion or contraction in a first direction (A) upon external pressure change, as seen on a cross sectional plane cut through the shell (4, 4', 4a, 4b, 4a', 4b'), the cross sectional plane being parallel with the first direction (A) and wherein the first direction (A) is determined by a wall thickness of the shell (4, 4', 4a, 4b, 4a', 4b'), which is chosen to be smaller than the wall thickness of the shell (4, 4', 4a, 4b, 4a', 4b') in other parts, at least along a partial length (L) of the wall (6a, 6b, 6a', 6b') in the cross sectional plane.2. The pressure sensitive element according to claim 1, wherein the partial length (L)
of the wall (6a, 6b, 6a', 6b') with a smaller thickness is oriented parallel with
the first direction (A).
3. The pressure sensitive element according to claim 1 or 2, wherein the shell (4, 4',
4a, 4b, 4a', 4b') is partially or in its entirety made of any of Teflon, rubber, polymer,
carbon, graphene or Kevlar or a combination thereof.
4. The pressure sensitive element according to any of the previous claims, wherein the
pressure sensitive fluid is any of air, natural gas, a gas, hydraulic oil, heavy oil
or lubricating oil, hydrogen, oxygen or helium.
5. The pressure sensitive element according to any of the previous claims, wherein the
shell (4, 4', 4a, 4b, 4a', 4b') is toroidal geometry and wherein the pressure sensitive
element is designed as a pressure sensitive sealing (2, 2', 2a, 2b, 2a', 2b'), wherein
a central axis (Z) and a center of the toroidal geometry defines a toroidal plane.
6. The pressure sensitive element according to claim 5, wherein the shell (4, 4', 4a,
4b') has a wall thickness that is smaller on its top and bottom periphery (8a, 8a',
13a, 13b) than a wall thickness in other areas such as an inner periphery or outer
periphery (10a, 10a', 12a, 12b), to allow expansion in the first direction (A) parallel
to the toroidal plane.
7. The pressure sensitive element according to claim 5, wherein the shell (4, 4', 4b,
4a) has a wall thickness that is smaller on the inner periphery (10b', 12b) and the
outer periphery (10b,12a) of the torus than a wall thickness in other areas such as
the top periphery and bottom periphery (8b, 8b'), to allow expansion in the first
direction (A) perpendicular to the toroidal plane.
8. The pressure sensitive element according to any of claims 5 to 7, wherein the toroidal
geometry of the shell (4, 4a, 4b) is shaped as a torus and wherein the pressure sensitive
element is an O-ring or sealing.
9. The pressure sensitive element according to any of claims 5 to 7, wherein the toroidal
geometry of the shell is a shaped as a pipe section (4', 4a', 4b') and wherein the
pressure sensitive element is a sealing.
10. A geothermal piping system comprising:
- a supply pipe (20) for delivering a fluid into a borehole (14);
- at least one retainer (16) shaped as a ring or elliptic ring designed to fit into the borehole (14), said at least one retainer (16) having a recess (18) to receive the supply pipe (20);
- a pressure sensitive element (2, 2', 2, 2a, 2b') in the form of a torus according to previous claim 6, wherein the pressure sensitive element in the form of the torus is arranged around the supply pipe (20), the recess (18) being designed so that the supply pipe (20) fits snug into the recess (18) whereby the pressure sensitive element exceeds the size of the recess (18) so that the pressure sensitive element (2, 2', 2, 2a, 2b') can hold and bear the weight of the supply pipe (20) at least along a limited length of the supply pipe (20), since the pressure sensitive element (2, 2', 2, 2a, 2b') is embracing the supply pipe (20) due to expansion in a cross sectional plane of the supply pipe (20).