Underground heat exchanger system with secured collapse prevention function through stent pipe reinforcement

Abstract

The underground heat exchanger system, which secures a function to prevent bore collapse through stent pipe reinforcement according to the present invention, is expected to ensure ease of construction and cost reduction effects for preventing bore collapse in open-type underground heat exchangers by effectively preventing bore collapse that frequently occurs in open-type underground heat exchangers. This is achieved by installing a subsurface protection casing up to a depth corresponding to soil and alluvium within the entire bore section of the geothermal bore drilled to utilize groundwater thermal energy, drilling the bedrock layer below the alluvium in a bare state to the required depth, and then inserting an in-hole logging camera into the drilled geothermal bore to observe the condition of the bore wall of the geothermal bore, identifying unstable sections where bore collapse is likely to occur or where there is a possibility of future bore collapse due to unstable strata or aquifer development, and then inserting and installing a circular stent pipe equipped with a strainer only in the identified unstable sections sequentially from the bottom of the geothermal bore.

Description

Technology Field

[0001] The present invention relates to an underground heat exchanger system in which a function to prevent bore collapse is secured by reinforcing with a stent pipe. More specifically, the invention relates to an underground heat exchanger system in which a function to prevent bore collapse is secured by reinforcing by inserting and fixing a stent pipe equipped with a strainer in an area where bore collapse is possible, in order to prevent bore collapse caused by unstable strata and aquifers found in a geothermal borehole drilled to utilize underground thermal energy. Background Technology

[0002] Geothermal energy is a general term for the heat contained in the ground and groundwater. Generally, geothermal wells are installed by drilling into the ground to utilize geothermal energy for cooling or heating. The open-type (SCW: Standing Column Well) method involves drilling into the ground to a depth of approximately 250 to 500 m, installing a circulation pump in the open geothermal well, and circulating groundwater to transfer thermal energy from the ground. In the case of an open-type geothermal system, the structure is such that a pumping pipe equipped with a circulation pump and a return pipe are installed within the geothermal well. The groundwater from the geothermal well is circulated through the pumping pipe equipped with the circulation pump to a heat exchanger in the building's mechanical room to transfer thermal energy from the ground. After the heat transfer is complete, the groundwater returns to the geothermal well through the return pipe, repeating this circulation process. The heat exchanger in the mechanical room utilizes the thermal energy rising from the groundwater within the geothermal well to generate the temperature required for cooling or heating.

[0003] In such open-loop geothermal systems, while heat exchangers in the machine room installed above ground are easy to inspect for failure causes and maintain, underground heat exchangers installed hundreds of meters below the surface face the problem that restoration is difficult and, furthermore, system operation is suspended if a geothermal well collapses.

[0004] To solve the problem of such well collapse, Korean Registered Patent Publication No. 10-1512303, "Circulating Structure Open-Type Geothermal System," discloses a circulating structure open-type geothermal system equipped with a spacing maintaining unit to keep a constant distance between a supply pipe that supplies underground groundwater to a heat exchanger and a return pipe that returns the groundwater heat-exchanged through the heat exchanger to the ground. By filling the well where the supply and return pipes are placed (inserted) with a filling material such as gravel, the system increases the inflow of groundwater into the supply pipe, prevents well collapse through the filling material, replaces bentonite—a source of groundwater contamination—and provides a filtration function for contaminated groundwater. Furthermore, it enables post-maintenance through surging (cleaning by applying pressure to air or water) in the event that the supply and return pipes become clogged by contaminants. However, this is a heat exchanger method of the aforementioned semi-open type, also known as a standing column well. This is a technology intended to compensate for the disadvantages of a closed-loop heat exchanger using a vertically inserted U-shaped tube, and to compensate for the disadvantages of Korean Registered Patent No. 10-1602826, in which the gap between the outer wall of the U-shaped tube and the inner wall of the borehole is filled with grouting. Instead of completely sealing the gap between the outer wall of the U-shaped tube and the inner wall of the borehole with grouting, it is a technology that replaces it with a filling material such as gravel so that groundwater can be exchanged through the supply pipe. However, this also cannot be considered a fundamental prevention of borehole collapse as the entire geothermal borehole is filled with a filling material such as gravel.

[0005] In addition, Korean Registered Patent No. 10-2920090, titled 'Open-type geothermal heating and cooling system and method capable of preventing borehole collapse using multiple synthetic resin casings,' discloses an open-type geothermal heating and cooling system capable of preventing borehole collapse by installing a steel pipe casing from the ground to the bedrock layer and a lower synthetic resin casing having multiple penetration holes formed throughout the entire length of the geothermal borehole, which is drilled vertically from the bedrock layer to the groundwater layer and is hundreds of meters deep, in order to minimize the problem of penetration holes becoming blocked due to the collapse of the geothermal borehole as illustrated in FIG. 1.

[0006] Korean Registered Patent No. 10-1668557, titled "Open-type Geothermal System Without Well Collapse," discloses an open-type geothermal system in which a perforated casing pipe made of synthetic resin, manufactured in a spiral or corrugated shape, is inserted and installed throughout the entire interior of a well to prevent the well from collapsing or the detachment of rock dust from the walls, thereby degrading the quality of groundwater. However, such methods had the problem of increasing construction time and material costs due to the insertion and installation of the inner casing throughout the entire geothermal well at depths of several hundred meters, and the method of installing a submersible pump inside the inner casing after installation had the drawback of requiring the use of only the groundwater flowing into the inner casing, which has a diameter that narrows compared to the diameter of the drilled geothermal well. Prior art literature

[0007] Korean Registered Patent Publication No. 10-2920090 Korean Registered Patent Publication No. 10-1512303 Korean Registered Patent Publication No. 10-1668557 Korean Registered Patent Publication No. 10-1834567 The problem to be solved

[0008] The present invention is intended to solve the aforementioned problems, and,

[0009] The present invention provides an underground heat exchanger system with a function to prevent bore collapse through stent pipe reinforcement, characterized by effectively preventing bore collapse that frequently occurs in open-type underground heat exchangers by installing a subsurface protection casing up to a depth corresponding to soil and alluvium within the total depth of bore hole drilled to utilize groundwater thermal energy, drilling the bedrock layer below the alluvium layer to the required depth in an open state, and then inserting a bore logging camera into the drilled bore hole to observe the condition of the bore wall of the geothermal well, identifying unstable sections where bore collapse has occurred or is judged to have a possibility of future collapse due to unstable strata or aquifer development, and then inserting and installing circular stent pipes equipped with strainers into the identified unstable sections sequentially starting from the bottom of the geothermal well.

[0010] In addition, the present invention provides an underground heat exchanger system with a function to prevent collapse of the hole through stent pipe reinforcement, characterized in that the circular stent pipe equipped with a strainer installed in the unstable section is equipped with a spiral section at the bottom that is assembled to the end of the drilling rod, and a connection port is provided at the entry end of the circular stent pipe equipped with a strainer that can apply pressure and vibration even if the centerline of the circular stent pipe equipped with a strainer inserted into the drilled geothermal hole does not coincide.

[0011] In addition, the present invention provides an underground heat exchanger system with a function to prevent collapse of the hole through reinforcement of a stent pipe, characterized in that the stent pipe, which is in the form of a circular tube equipped with a strainer installed in an unstable section, is equipped with a plurality of tension springs on the outer surface of the stent pipe to prevent detachment from the wall surface, thereby allowing it to be easily inserted into the geothermal hole and fixed in a stationary position. means of solving the problem

[0012] The underground heat exchanger system having a function to prevent collapse of the hole through reinforcement of the stent pipe according to the present invention comprises a geothermal hole (100) developed to utilize underground thermal energy, a subsurface protection casing (110) installed to a depth corresponding to the soil and alluvium layer of the geothermal hole (100), an unstable section (200) determined by observing the condition of the hole wall (120) of the geothermal hole by inserting an in-hole logging camera (A) into the geothermal hole (100) up to the bottom (101) of the geothermal hole, and a circular stent pipe (300) equipped with a strainer (310) inserted into and fixed in the unstable section (200).

[0013] The above stent tube (300) is provided with a spiral connection member (330) that can be spirally connected to a drill rod (20) on the lower part of the inner side (320), and a plurality of elastic fixing members (340) on the outer side (310) that can be pressed against the inner wall of the geothermal hole (100).

[0014] It has the feature of inserting and fixing a stent tube (300) sequentially from the bottom (101) of the geothermal hole to the top (102) of the geothermal hole into the unstable section (200) measured inside the geothermal hole (100).

[0015] Additionally, the above-mentioned spiral connector (330) is provided with a rod connection part (334) formed by a knuckle thread, and the above-mentioned fixing part (340) is formed such that when the upper part (341) and lower part (342) are fixed, the fixing part (340) is compressed according to the inner diameter of the geothermal hole (100) when inserted into the geothermal hole (100), and expands and is fixed when stopped.

[0016] Additionally, the above-mentioned spiral connector (330) is formed with a tube insertion part (331) on the upper side so that it can be inserted into the lower inner side of the stent tube, and a conical end (333) on the lower side so that it can be easily inserted into the geothermal hole (100). It is provided with a catch (332) that can catch and fix the lower end of the stent tube on the lower line of the tube insertion part (331). The outer diameter end (3321) of the catch (332) is larger than the outer diameter of the stent tube and smaller than the inner diameter of the geothermal hole, so that the cross-sectional shape up to the conical end (333) is formed with the upper part being wide and the lower part being narrow.

[0017] The inner diameter of the above-mentioned spiral connector (330) is provided with a rod connection part (334) which is a female screw formed with a knuckle thread, so that the end (21) of the rod (20) provided in the drilling machine (10) vibrates and moves back and forth is connected to the knuckle thread, and the screw thread of the knuckle thread formed on the rod connection part (334) and the end (21) of the rod (20) is formed in a curved shape so that the force is distributed to prevent damage to the screw thread, so that when the stent tube (300) is inserted into the geothermal hole (100), the damaged rock protruding into the geothermal hole (100) in the unstable section (200) can be inserted while being cut off by the vibration and back-and-forth pressure transmitted from the end (21) of the rod (20). Effects of the invention

[0018] The underground heat exchanger system with a function to prevent bore collapse through stent pipe reinforcement according to the present invention prevents bore collapse by reinforcing the stent pipe in unstable sections where bore collapse has occurred or is judged to be likely to occur in the future due to unstable strata and aquifer development, and can increase heat exchange efficiency by maintaining the cross-sectional area of ​​the groundwater circulation space in most of the remaining geothermal borehole drilling sections.

[0019] In addition, a connection port that is assembled to a drilling rod is provided at the lower end of a circular stent tube equipped with a strainer installed in an unstable section, so that even if the centerline of the circular stent tube equipped with a strainer inserted into a drilled geothermal hole does not align, installation is easy due to the pressure and vibration of the drilling machine, thereby increasing the convenience of installation and construction.

[0020] In addition, a circular stent pipe equipped with a strainer installed in an unstable section is equipped with a plurality of tension springs on the outer surface of the stent pipe to prevent detachment from the wall, allowing it to be easily inserted into the geothermal hole and fixed in a stationary position, thereby fundamentally preventing defects caused by the collapse of the geothermal hole. Brief explanation of the drawing

[0021] Figure 1 is a drawing illustrating the construction process of an open geothermal heating and cooling system capable of preventing collapse using multiple synthetic resin casings according to the prior art. FIG. 2 is an installation diagram of an underground heat exchanger system in which a function to prevent collapse of the pipe is secured by reinforcing the stent pipe according to the present invention. FIG. 3 is a perspective view illustrating a stent tube according to the present invention. FIG. 4 is a cross-sectional view illustrating a stent tube according to the present invention. FIG. 5 is a diagram illustrating the shape of a geothermal well (100) developed to utilize underground thermal energy, the process of installing a subsurface protection casing (110) installed to a depth corresponding to the soil and alluvium layer of the geothermal well (100), and inserting an in-hole logging camera (A) into the geothermal well (100) up to the bottom (101) to observe the condition of the wall (120) of the geothermal well and confirming the unstable section (200) determined to be an unstable layer and an aquifer. FIG. 6 is a drawing illustrating the process of installing and fixing the stent pipe of the present invention from the bottom in an unstable section (200) observed and confirmed in a geothermal well. FIG. 7 is a drawing showing the shape in which a circulation pump, a pumping pipe, and a return pipe are installed to move and circulate groundwater to a machine room heat exchanger inside a geothermal well (100) in which a stent pipe (300) has been installed. . Specific details for implementing the invention

[0022] Hereinafter, an underground heat exchanger system with a function to prevent collapse of the pipe by reinforcing the stent pipe according to a preferred embodiment of the present invention will be described in detail with reference to the drawings.

[0023] In the following description of the present invention, if it is determined that a detailed description of related known functions or configurations may unnecessarily obscure the essence of the present invention, such detailed description will be omitted.

[0024] In addition, when it is mentioned that a component is "connected" or "joined" to another component, it may be directly connected or joined to that other component, or there may be other components in between.

[0025] FIG. 2 illustrates an installation configuration for a geothermal heat exchanger system with a function to prevent borehole collapse secured by reinforcing a stent pipe according to the present invention. This system utilizes a method of transferring underground thermal energy by drilling the geological layer to a depth of approximately 250–500 m, similar to a conventional open-type (SCW: Standing Column Well) geothermal heat exchanger, installing a circulation pump in the bare geothermal well, and circulating groundwater. To prevent borehole collapse occurring in unstable layers and aquifer development sections appearing in the middle of the bedrock layer of the bare geothermal well drilled to a depth of approximately 250–500 m, an in-hole logging camera is inserted into the drilled geothermal well to observe the condition of the borehole wall. Furthermore, a circular stent pipe equipped with a strainer is inserted and installed from the bottom to the top of the geothermal well into specific unstable sections where collapse is judged to have occurred or is likely to occur in the future due to unstable layers or aquifer development. FIG. 3 is a perspective view for explaining a stent tube according to the present invention, and FIG. 4 is a cross-sectional view for explaining a stent tube according to the present invention.

[0026] In addition, FIG. 5 is a diagram illustrating the shape of a geothermal well (100) developed to utilize underground thermal energy, the process of installing a subsurface protection casing (110) installed to a depth corresponding to the soil and alluvium layer of the geothermal well (100), and inserting an in-hole logging camera (A) into the geothermal well (100) up to the bottom (101) to observe the condition of the wall (120) of the geothermal well and confirm an unstable section (200) determined to be an unstable layer and an aquifer development, and FIG. 6 is a diagram illustrating the process of installing and fixing a stent pipe of the present invention in the unstable section (200) observed and confirmed in the geothermal well.

[0027] In addition, FIG. 7 is a drawing showing the configuration in which a circulation pump (deep well pump) and a pumping pipe are installed to move and circulate groundwater to a machine room heat exchanger inside a geothermal well (100) in which a stent pipe (300) has been installed, and a return pipe is installed to return groundwater to the inside of the geothermal well after heat exchange in the machine room. .

[0029] The underground heat exchanger system, which has a function to prevent the collapse of a borehole by reinforcing a stent pipe according to the present invention, comprises a geothermal borehole (100) developed to utilize underground thermal energy, a subsurface protection casing (110) installed to a depth corresponding to the soil and alluvium layer of the geothermal borehole (100), and an unstable section (200) determined to be an unstable layer and aquifer by inserting an in-borehole logging camera (A) into the geothermal borehole (100) up to the bottom (101) of the geothermal borehole to photograph and observe the condition of the borehole wall (120) of the geothermal borehole, and inserting and fixing a circular stent pipe (300) equipped with a strainer that is inserted and fixed into the unstable section (200) determined as above, and the stent pipe (300) is capable of being spirally connected to an excavator rod (20) at the bottom of the inner side (320). A spiral connector (330) and a plurality of elastic fixing parts (340) on the outer side (310) to be able to apply pressure to the inner wall of the geothermal hole (100), and

[0030] This is an underground heat exchanger system in which each stent pipe (300) is inserted and fixed sequentially from the bottom (101) of the geothermal hole to the top (102) of the geothermal hole in the unstable section (200) determined in the above geothermal hole (100).

[0031] The above stent tube (300) is provided with a spiral connector (330) on the lower inner side (320) of the stent tube (300) so that it can be inserted into the geothermal hole (100) developed to utilize underground thermal energy.

[0032] The spiral connector (330) provided at the lower inner side (320) of the above-mentioned stent tube (300) is a connector capable of spirally connecting the lower inner side (320) of the stent tube (300) and the drilling rod (20) in order to insert and fix a circular tube-shaped stent tube (300) equipped with a strainer into an unstable section identified by inserting an in-hole logging camera into the drilled geothermal hole of the bedrock layer. The spiral connector (330) has a pipe insertion part (331) at the upper side that can be inserted into the lower inner side of the stent tube, and a conical end (333) formed at the lower side that can be easily inserted into the geothermal hole (100).

[0033] A catch (332) is formed on the lower line of the above-mentioned tube insertion part (331) so that the lower end of the stent tube can be caught and fixed. The outer diameter end (3321) of the catch (332) is formed to be larger than the outer diameter of the stent tube and smaller than the inner diameter of the geothermal hole, so that the cross-section up to the above-mentioned conical end (333) is formed to be wider at the top and narrower at the bottom. A rod connection part (334), which is a female screw formed as a knuckle thread, is provided in the inner diameter of the above-mentioned spiral connector (330) so as to be connected by a knuckle thread to the end (21) of the rod (20) that is provided in the drilling machine (10) and vibrates and moves back and forth.

[0034] In addition, the screw threads of the round screw (Knuckle Thread) formed on the rod connection part (334) and the end (21) of the drilling rod (20) are curved so that the force is distributed to prevent damage to the screw threads, thereby providing durability so that when inserting the stent tube (300) into the geothermal hole (100), the damaged rock protruding into the geothermal hole (100) in the unstable section (200) can be cut off by the vibration and forward / backward pressure transmitted from the end (21) of the rod (20).

[0035] In addition, because the threads of the aforementioned knuckle thread are round, they engage and disengage easily even if foreign substances such as dust or sand get stuck, and the foreign substances are easy to clean.

[0036] In addition, when fastened with the above-mentioned knuckle thread, a gap is created between the threads, so that even when fastened to the end of the excavator rod (20) at the lower part of the inner side (320) of the stent tube (300), the upper side of the stent tube (300) can be moved in any direction of 360 degrees, so that even if the center line of the stent tube in the shape of a circular tube equipped with a strainer to be inserted does not coincide with the drilled geothermal hole, the upper side of the stent tube (300) can be moved according to the condition of the geothermal hole and inserted into the drilled geothermal hole by the pressure of the excavator rod (20).

[0037] In addition, the outer diameter end (3321) of the catch (332) of the spiral connector (330) is fixed by being stepped close to the inner diameter of the geothermal hole, thereby preventing foreign substances such as rocks and rock dust that are lost and fall from the unstable section (200) of the geothermal hole from falling to the bottom of the geothermal hole by being accumulated and fixed between the catch (332) and the inner diameter of the geothermal hole.

[0038] In addition, the outer side (310) of the stent tube (300) is provided with a plurality of elastic fixing parts (340) to be able to apply pressure to the inner wall of the geothermal hole (100).

[0039] The above fixing part (340) is configured to be fixed after inserting a stent tube (300) into a specific unstable section (200) by inserting an in-hole logging camera into the drilled rock layer geothermal hole (100) to observe the condition of the hole wall of the geothermal hole. When inserted into the geothermal hole (100), the diameter is reduced along the hole wall of the geothermal hole (100) by a semi-elliptical pressure spring (343) in which the upper (341) and lower (342) parts are fixed to the outer surface of the stent tube (300), and after the stent tube (300) is fixed, the fixing force is expanded by the elastic force of the pressure spring (343).

[0040] In addition, to improve the fixation force of the stent tube (300), an elastic fixing part (350) that is expanded outwardly in a trumpet shape may be further provided at the top of the stent tube (300).

[0041] The above elastic fixing part (350) can be used by expanding the upper end of the stent tube (300) into a trumpet shape that is flared outwards.

[0042] The outer diameter of the above elastic fixing part (350) is formed to be at least 20 mm larger than the diameter of the geothermal hole (100).

[0043] The present invention is not limited to the specific preferred embodiments described above, and any person skilled in the art to which the invention pertains can make various modifications without departing from the essence of the invention as claimed in the claims, and such modifications will be within the scope of the claims. Explanation of the symbols

[0045] 10 : Drilling rig 20 : Drilling rig rod 100 : Geothermal well 110 : Subsurface protection casing 120 : Wellwall of the geothermal well 200 : Unstable section 300 : Stent tube 310 : Outer side of stent tube 320: Inner side of stent tube 330: Spiral connector 331 : Tube insertion part 332 : Stopper 333: Conical end 334: Rod connection 340 : Fixed part A: In-situ logging camera

Claims

Claim 1 A geothermal well (100) developed to utilize underground thermal energy; a subsurface protection casing (110) installed to a depth corresponding to the soil and alluvium layer of the geothermal well (100); an unstable section (200) determined by inserting an in-hole logging camera (A) into the geothermal well (100) up to the bottom (101) of the geothermal well to photograph the condition of the borehole wall (120) of the geothermal well; and a circular tube-shaped stent pipe (300) equipped with a strainer inserted into and fixed in the unstable section (200); wherein the stent pipe (300) has a spiral connection port (330) that can be spirally connected to an excavator rod (20) at the lower inner side (320) of the stent pipe (300), and on the outer side (310) of the stent pipe (300) the An underground heat exchanger system having a function to prevent collapse of the hole through stent pipe reinforcement, characterized by having a plurality of elastic fixing parts (340) to be able to apply pressure to the inner wall of the geothermal hole (100), and sequentially inserting and fixing the stent pipe (300) in each unstable section (200) confirmed by in-hole logging camera photography from the top (102) of the geothermal hole to the bottom (101) of the geothermal hole. Claim 2 In claim 1, the spiral connector (330) is provided with a rod connection part (334) formed of a knuckle thread, and the fixing part (340) is formed such that when the stent pipe (300) is inserted into the geothermal hole (100), it is formed to be compressed according to the inner diameter of the geothermal hole (100) by a semi-elliptical pressure spring (343) in which the upper part (341) and the lower part (342) are fixed, and after the stent pipe (300) is installed in the unstable section (200), it expands to increase the fixing force, thereby forming an underground heat exchanger system with a function to prevent collapse of the hole through stent pipe reinforcement.

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