Open-type same-well heat exchange device for medium-deep geothermal well development

Abstract

The invention relates to the technical field of geothermal development, and provides an open type same-well heat exchange device for medium-deep geothermal well development, which comprises a wellhead device, a main body component and a temperature monitoring device. The wellhead device is provided with a heat exchange medium extraction hole and a heat exchange medium injection hole, and the extraction hole and the injection hole are both circularly connected with the heat exchanger through a ground heat exchange pipeline; the main body component comprises a heat exchange tubular column string, a sleeve and a heat exchange unit, the heat exchange tubular column string and the sleeve are both arranged at the bottom of the wellhead device, a heat exchange extraction channel is constructed in the heat exchange tubular column string, the heat exchange extraction channel is communicated with the heat exchange medium extraction hole, an underground reinjection channel is constructed between the heat exchange tubular column string and the sleeve, and the underground reinjection channel is communicated with the heat exchange medium extraction hole. The underground reinjection channel is communicated with the heat exchange medium injection hole; and the temperature monitoring device is arranged between the heat exchange tubular column string and the sleeve. When the abandoned well in the prior art is transformed into the geothermal well, same-well development can be carried out, so that the purpose of taking heat without taking water is achieved, the purpose of clean and efficient utilization of geothermal resources is achieved, and the service life of the abandoned well is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of geothermal development, and in particular to an open same-well heat exchange device for developing medium-deep geothermal wells. Background Art

[0002] With the increase of oil production, the oil output of many oil fields has been declining year by year, and the number of abandoned oil wells has been increasing year by year. Directly abandoning all such geothermal wells or oil and gas wells will cause a waste of resources. At present, how to transform and utilize abandoned oil field wells and use geothermal heating or power generation for various buildings in cities near abandoned oil field wells will have huge economic, social and environmental benefits.

[0003] Due to the extensive development and utilization of geothermal energy, a large amount of tail water from geothermal heating is discharged, resulting in serious waste of resources, and causing problems such as reduced heat storage pressure, surface soil and water pollution. With increasingly high environmental protection requirements, research and experiments such as "taking heat without taking water" and "underground closed heat exchange" are encouraged and supported. Transforming existing geothermal wells or oil and gas wells into geothermal wells that "take heat without taking water" and "underground closed heat exchange" can save a lot of drilling costs and reuse waste resources.

[0004] In the related technologies, the following two methods are used for transformation: one is to transform abandoned oil and gas wells into conventional water wells, which cannot meet the technical requirements of "extracting heat without taking water". The other is to use a packer to seal the water extraction layer or the oil and gas well development layer, and then use buried pipes to extract underground heat energy, which makes it impossible to fully utilize the heat of the high-temperature layer section at the bottom of the geothermal well or oil and gas well, and the heat exchange efficiency of the buried pipes is relatively low. Summary of the invention

[0005] The present invention provides an open same-well heat exchange device for the development of medium-deep geothermal wells, which is used to solve at least one of the above-mentioned technical defects in the prior art. When the abandoned wells in the prior art are converted into geothermal wells through the open same-well heat exchange device for the development of medium-deep geothermal wells, the same-well development can be carried out to achieve the purpose of "extracting heat without taking water", thereby realizing the purpose of clean and efficient utilization of geothermal resources and extending the service life of the abandoned wells.

[0006] The invention provides an open same-well heat exchange device for developing medium-deep geothermal wells, comprising a wellhead device, a main body component and a temperature monitoring device.

[0007] The wellhead device is arranged at the wellhead of the heat exchange well, and the wellhead device is provided with a heat exchange medium production hole and a heat exchange medium injection hole, and the heat exchange medium production hole and the heat exchange medium injection hole are both connected to the heat exchanger circulation through the ground heat exchange pipeline; The main body component is suitable for extending into the formation, and the main body component includes a heat exchange string string, a casing and a heat exchange unit. The heat exchange string string and the casing are both arranged at the bottom of the wellhead device. A heat exchange production channel is constructed inside the heat exchange string string, and the heat exchange production channel is connected to the heat exchange medium production hole. A downhole reinjection channel is constructed between the heat exchange string string and the casing, and the downhole reinjection channel is connected to the heat exchange medium injection hole; The temperature monitoring device is arranged between the heat exchange column string and the casing, and is used to monitor the temperature of the heat exchange medium at different positions inside and outside the heat exchange column string.

[0008] According to the open same-well heat exchange device for the development of medium-deep geothermal wells provided by the present invention, the temperature monitoring device includes an insulating temperature measuring short section and an external temperature measuring component. The insulating temperature measuring short section is connected to the pipe section of the heat exchange pipe string and is used to monitor the temperature of the corresponding position inside the heat exchange pipe string; the external temperature measuring component is arranged between the heat exchange pipe string and the casing, and is used to monitor the temperature of the corresponding position outside the heat exchange pipe string.

[0009] According to the open same-well heat exchange device for the development of medium-deep geothermal wells provided by the present invention, the thermal insulation and temperature measuring short section includes a mounting component and an internal temperature measuring component. The mounting component is provided with threads near both ends, and the threads are matched with the threads of the corresponding pipe sections of the heat exchange pipe string. The internal temperature measuring component is arranged inside the mounting component to monitor the temperature of the corresponding position inside the heat exchange pipe string.

[0010] According to the open same-well heat exchange device for the development of medium-deep geothermal wells provided by the present invention, the installation component includes an inner tube, an insulation layer and an outer tube stacked in sequence from the inside to the outside, the inner tube is welded to the inner wall of the outer tube, and a sealed cavity is defined between the inner tube and the outer tube, the insulation layer is located in the sealed cavity, the insulation layer is provided with an installation cavity, the outer tube is provided with an opening connected to the installation cavity, the internal temperature measuring component is provided in the installation cavity, and the position of the opening is sealed and connected with a protective shell by fastening bolts.

[0011] According to the open type same-well heat exchange device for the development of medium-deep geothermal wells provided by the present invention, the internal temperature measurement component includes a wireless transmitter assembly and a temperature sensor; The wireless transmitter assembly includes an electrically connected coil, a transmitter core tube and a signal module, and the coil, the transmitter core tube and the signal module are all packaged in the installation cavity through a transmitter sealing shell; The temperature sensor is embedded in the tube wall of the inner tube, and the temperature sensor is electrically connected to the signal module through a wire.

[0012] According to the open same-well heat exchange device for the development of medium-deep geothermal wells provided by the present invention, the external temperature measuring component includes an armored optical cable, and the armored optical cable is arranged on the outer surface of the heat exchange pipe string through an optical cable clamp, and the spacing between two adjacent optical cable clamps is 8m-10m.

[0013] According to the open type same-well heat exchange device for the development of medium-deep geothermal wells provided by the present invention, the heat exchange pipe string comprises a second water intake pipe, a first water intake pipe and a pump chamber pipe connected in sequence from bottom to top, the length of the second water intake pipe accounts for 1 / 5 of the total length of the heat exchange pipe string, and the bottom pipe string of the second water intake pipe is provided with perforations in the circumferential direction; The second water intake pipe, the first water intake pipe and the pump chamber pipe are all heat-insulating pipes; or the pump chamber pipe and the first water intake pipe are heat-insulating pipes, and the second water intake pipe is a steel pipe or a PE pipe; The heat exchange unit is arranged inside the pump chamber pipe and is passed through the cable passing hole of the wellhead device through a steel wire power cable.

[0014] According to the open type heat exchange device for developing medium-deep geothermal wells provided by the present invention, the heat exchange unit includes a fishing head, a sealing cylinder, a sealing rubber cylinder, an anchoring slip assembly, a deep well high temperature resistant electric submersible pump unit, a motor and a centralizer connected in sequence from top to bottom; The deep well high temperature resistant electric submersible pump group is provided with a pump water inlet and a water outlet, the pump water inlet is located below the setting rubber cylinder, and the water outlet is located above the setting rubber cylinder; A downhole monitor and a protector are provided below the deep well high temperature resistant submersible pump group. The downhole monitor is electrically connected to the deep well high temperature resistant submersible pump group and is used to monitor the operation of the deep well high temperature resistant submersible pump group. The protector is used to protect the motor.

[0015] According to the open same-well heat exchange device for the development of medium-deep geothermal wells provided by the present invention, the heat exchange unit also includes a pressure sensor, which is arranged on the upper and lower end faces of the sealing rubber cylinder. The pressure sensor is connected to the downhole monitor through a lead cable and is used to monitor the pressure at both ends of the sealing rubber cylinder.

[0016] According to the open type same-well heat exchange device for the development of medium-deep geothermal wells provided by the present invention, the wellhead device comprises a casing head body, a riser flange and a completion flange connected sequentially from bottom to top; The casing head body defines a first inner cavity, the upper end of the first inner cavity is sealedly connected to a heat exchange column string hanger, and the lower end of the first inner cavity is sealedly connected to a casing hanger; The raised flange defines a second inner cavity, which is connected to the heat exchange tubing string hanger; the heat exchange medium production hole is arranged on the completion flange, and the completion flange is also provided with a cable through hole and an optical cable through hole; the heat exchange medium injection hole is arranged on the side wall of the raised flange and extends to penetrate the casing hanger.

[0017] The open type heat exchange device for developing medium-deep geothermal wells provided by the present invention is provided with a heat exchange medium extraction hole and a heat exchange medium injection hole in the wellhead device, and the heat exchange medium extraction hole and the heat exchange medium injection hole are both connected to the heat exchanger circulation through the ground heat exchange pipeline, and a heat exchange extraction channel is constructed inside the heat exchange pipe string, and the heat exchange extraction channel is connected to the heat exchange medium extraction hole, and a downhole reinjection channel is constructed between the heat exchange pipe string and the casing, and the downhole reinjection channel is connected to the heat exchange medium injection hole. When the abandoned well in the prior art is transformed into a geothermal well by the open type heat exchange device for developing medium-deep geothermal wells, the same well development can be carried out to achieve the purpose of "taking heat without taking water", thereby achieving the purpose of clean and efficient utilization of geothermal resources and extending the service life of the abandoned well.

[0018] In addition, by setting a temperature monitoring device between the heat exchange string and the casing to monitor the temperature of the heat exchange medium at different positions on the inside and outside of the heat exchange string, the geothermal system can intelligently adjust the heat exchange rate and working mode based on the temperature monitoring results to ensure the optimal utilization of thermal energy, reduce energy consumption, and increase economic benefits; and through trend analysis of historical temperature data, predict the aging degree and maintenance cycle of equipment, achieve precise maintenance, and reduce unnecessary downtime and cost expenditure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 It is a schematic structural diagram of an open same-well heat exchange device for developing medium-deep geothermal wells provided by an embodiment of the present invention.

[0021] Figure 2 It is a cross-sectional view of an open same-well heat exchange device for medium-deep geothermal well development provided by an embodiment of the present invention.

[0022] Figure 3 It is a cross-sectional view of a heat-insulating temperature measuring short section in an open same-well heat exchange device for developing medium-deep geothermal wells provided by an embodiment of the present invention.

[0023] Reference numerals: 1. Heat exchange unit; 2. Heat exchange string; 3. Casing; 4. Formation; 5. Wellhead device; 6. Temperature monitoring device; 7. Heat exchange production channel; 8. Downhole reinjection channel; 9. Heat exchanger; 10. Ground heat exchange pipeline; 301, optical cable through hole; 302, heat exchange column string hanger; 303, heat exchange medium injection hole; 304, casing hanger; 305, heat exchange medium extraction hole; 306, cable through hole; 307, rising flange; 308, casing; 309, pump room pipe; 310, pressure sensor; 311, lead cable; 312, optical cable clamp; 313, first water intake pipe; 314, thermal insulation Temperature measuring nipple; 315, armored optical cable; 316, second water intake pipe; 317, optical cable dead blockage; 318, steel wire power cable; 319, fishing head; 320, sealing cylinder; 321, setting rubber cylinder; 322, anchoring slip assembly; 323, deep well high temperature resistant submersible pump group; 324, pump water inlet; 325, protector; 326, downhole monitoring instrument; 327, centralizer; 328, motor; 401, thread; 402, welding point; 403, outer tube; 404, protective shell; 405, fastening bolts; 406, wireless transmitter assembly; 407, coil; 408, transmitter core tube; 409, signal module; 410, transmitter sealing shell; 411, wire; 412, temperature sensor; 413, cover sealing groove and sealing ring; 414, sensor mounting hole and sealing ring; 415, thermal insulation layer; 416, inner tube. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the description of the embodiments of the present invention, it should be noted that the terms "upper", "lower", "bottom", "axial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0026] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connection" and "configuration" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances. In addition, the term "multiple" in this application refers to two or more.

[0027] In the description of this specification, the description with reference to the terms "specific embodiment", "some embodiments", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0028] Figure 1 It is a schematic structural diagram of an open same-well heat exchange device for developing medium-deep geothermal wells provided by an embodiment of the present invention. Figure 2 It is a cross-sectional view of an open same-well heat exchange device for medium-deep geothermal well development provided by an embodiment of the present invention.

[0029] See also Figure 1 and Figure 2 An embodiment of the present invention provides an open heat exchange device for developing medium-deep geothermal wells. The open heat exchange device for developing medium-deep geothermal wells includes a wellhead device 5, a main body component and a temperature monitoring device.

[0030] The wellhead device 5 is provided at the wellhead of the heat exchange well, and is used to connect the main components of the heat exchange device with the ground facilities, and to exchange heat with the formation 4 through the main components of the heat exchange device, and to allow water (i.e., the heat exchange medium) to circulate and enter the ground facilities for energy conversion. The wellhead device 5 is provided with a heat exchange medium extraction hole 305 and a heat exchange medium injection hole 303, and both the heat exchange medium extraction hole 305 and the heat exchange medium injection hole 303 are circulatedly connected to the heat exchanger 9 through the ground heat exchange pipeline 10.

[0031] The heat exchanger 9 can provide heat for the user end for heating or power generation. The heat exchange medium extraction hole 305 is used to extract the circulating medium from the well. The heat exchange medium injection hole 303 is opposite to the heat exchange medium extraction hole 305. The heat exchange medium injection hole 303 is used to return the medium after heat exchange treatment to the formation 4, forming a closed-loop energy exchange process.

[0032] The main body component is suitable for extending into the formation 4, and the main body component includes a heat exchange tubing string 2, a casing 3 / 308 and a heat exchange unit 1. The heat exchange tubing string 2 and the casing 3 / 308 are both arranged at the bottom of the wellhead device 5. A heat exchange production channel 7 is constructed inside the heat exchange tubing string 2, and the heat exchange production channel 7 is connected to the heat exchange medium production hole 305. A downhole reinjection channel 8 is constructed between the heat exchange tubing string 2 and the casing 3 / 308, and the downhole reinjection channel 8 is connected to the heat exchange medium injection hole 303.

[0033] The heat exchange string 2 is composed of a series of closely arranged hollow tubes and is a long strip structure that runs through the depth of the well. The heat exchange string 2 contains a heat exchange extraction channel 7 for circulating the heat exchange medium that has carried the heat energy in the formation 4. A certain distance is left between the bottom of the heat exchange string and the bottom of the artificial well, which can be set to 10m from the bottom of the artificial well, so that the circulating medium can flow into the heat exchange extraction channel. The casing 3 / 308 surrounds the outside of the heat exchange string 2 to form an underground reinjection channel 8, which serves as a way for the medium after heat exchange to return to the underground and promote circulation. The casing 3 / 308 can be used as part of an open same-well heat exchange device for the development of medium-deep geothermal wells, or the original casing of the improved heat exchange well can be used.

[0034] The temperature monitoring device 6 is arranged between the heat exchange column string 2 and the casing 3 / 308, and is used to monitor the temperature of the heat exchange medium at different positions inside and outside the heat exchange column string 2.

[0035] Among them, in the process of geothermal energy utilization, accurately grasping the temperature of the heat exchange medium between the heat exchange string string 2 and the casing 3 / 308 plays an important role in optimizing system efficiency and preventing failures. The temperature monitoring device 6 can be a temperature sensor, and the temperature monitoring device 6 is deployed along the inside and outside of the heat exchange string string 2, covering key points from the wellhead to the bottom to ensure comprehensive data acquisition. The temperature monitoring device 6 can transmit the monitored temperature information to the central control system in real time through wireless or wired signals, which is convenient for remote monitoring and analysis.

[0036] It can be understood that the open type heat exchange device for developing medium-deep geothermal wells provided in the embodiment of the present invention is provided with a heat exchange medium production hole 305 and a heat exchange medium injection hole 303 in the wellhead device 5, and the heat exchange medium production hole 305 and the heat exchange medium injection hole 303 are both connected to the heat exchanger 9 through the ground heat exchange pipeline 10, and a heat exchange production channel 7 is constructed inside the heat exchange string 2, and the heat exchange production channel 7 is connected to the heat exchange medium production hole 305, and a downhole reinjection channel 8 is constructed between the heat exchange string 2 and the casing 3 / 308, and the downhole reinjection channel 8 is connected to the heat exchange medium injection hole 303. When the abandoned well in the prior art is transformed into a geothermal well by the open type heat exchange device for developing medium-deep geothermal wells, the same well development can be carried out to achieve the purpose of "taking heat without taking water", thereby achieving the purpose of clean and efficient utilization of geothermal resources and extending the service life of the abandoned well.

[0037] In the related art, conventional geothermal wells are developed by different wells, one for production and one for reinjection, which requires at least two wells. The heat exchange medium cannot completely flow back to the formation 4, and the purpose of "extracting heat without extracting water" cannot be achieved.

[0038] In addition, by setting a temperature monitoring device 6 between the heat exchange column string 2 and the casing 3 / 308 to monitor the temperature of the heat exchange medium at different positions on the inside and outside of the heat exchange column string 2, based on the temperature monitoring results, the geothermal system can intelligently adjust the heat exchange rate and working mode to ensure the optimal utilization of thermal energy, reduce energy consumption, and increase economic benefits; and through trend analysis of historical temperature data, the aging degree and maintenance cycle of the equipment are predicted to achieve accurate maintenance and reduce unnecessary downtime and cost expenditure.

[0039] Continue reading Figure 2 In some embodiments of the present invention, the temperature monitoring device 6 includes an insulated temperature measuring short section 314 and an external temperature measuring component. The insulated temperature measuring short section 314 is connected to the pipe section of the heat exchange column string 2 and is used to monitor the temperature of the corresponding position inside the heat exchange column string 2; the external temperature measuring component is arranged between the heat exchange column string 2 and the casing 3 / 308 and is used to monitor the temperature of the corresponding position outside the heat exchange column string 2.

[0040] The insulated temperature measuring nipple 314 is directly embedded in the heat exchange column string 2 and seamlessly connected to the pipe section of the heat exchange column string 2. The insulated temperature measuring nipple 314 has a built-in sensor for measuring the temperature of the heat exchange medium flowing through the pipe. The insulated temperature measuring nipple 314 is wrapped with high-performance insulation materials to ensure that it can block external temperature interference even under extreme conditions and ensure the accuracy of the readings.

[0041] The external temperature measuring component is located between the heat exchange string string 2 and the casing 3 / 308, that is, the downhole space, and is in direct contact with the surrounding heat exchange medium.

[0042] Figure 3It is a cross-sectional view of a heat-insulating temperature measuring short section in an open same-well heat exchange device for developing medium-deep geothermal wells provided by an embodiment of the present invention.

[0043] See also Figure 3 In some embodiments of the present invention, the thermal insulation temperature measuring short section 314 includes a mounting component and an internal temperature measuring component. The mounting component is provided with threads 401 near both ends, and the threads 401 cooperate with the corresponding pipe section threads of the heat exchange column string 2. The internal temperature measuring component is arranged inside the mounting component to monitor the temperature of the corresponding position inside the heat exchange column string 2.

[0044] The mounting component is equipped with a threaded 401 interface, which is convenient and quick to connect with the corresponding pipe section of the heat exchange column string 2 to ensure a stable fit without leakage. The mounting component is usually made of heat-insulating materials to prevent the external temperature from affecting the reading and ensure the accuracy of the measurement. The internal temperature measuring component is placed in the center of the mounting component, directly contacting the heat exchange medium flowing through the pipe, to achieve real-time monitoring of the medium temperature.

[0045] Continue reading Figure 3 In some embodiments of the present invention, the installation component includes an inner tube 416, an insulation layer 415 and an outer tube 403 which are stacked in sequence from the inside to the outside. The inner tube 416 is welded to the inner wall of the outer tube 403 to form a welding point 402, and a sealed cavity is limited between the inner tube 416 and the outer tube 403. The insulation layer 415 is located in the sealed cavity. The insulation layer 415 is provided with an installation cavity. The outer tube 403 is provided with an opening connected to the installation cavity. The internal temperature measuring component is provided in the installation cavity. The position of the opening is sealed and connected to a protective shell 404 by a fastening bolt 405.

[0046] Among them, the inner tube 416 is in direct contact with the heat exchange medium and is usually made of high temperature resistant and corrosion resistant materials to ensure strength and life. The thermal insulation layer 415 is located in the sealed cavity formed between the inner tube 416 and the outer tube 403. The thermal insulation layer 415 is made of high-quality thermal insulation materials, such as aerogel, aluminum foil and glass fiber composite material layers, which effectively isolate external temperature fluctuations and maintain the stability of the internal temperature measurement environment. The outer tube 403 is mainly used as a load-bearing outer shell to resist external pressure and ensure the firmness of the overall structure. At the same time, an opening connected to the installation cavity is reserved to facilitate the installation of internal components. The protective shell 404 blocks the opening on the outer tube 403 and is fixed with fastening bolts 405 to form the last physical barrier, enhance the sealing effect, and protect the internal temperature measurement components from damage.

[0047] Continue reading Figure 3In some embodiments of the present invention, the internal temperature measurement component includes a wireless transmitter assembly 406 and a temperature sensor 412; the wireless transmitter assembly 406 includes an electrically connected coil 407, a transmitter core tube 408 and a signal module 409, and the coil 407, the transmitter core tube 408 and the signal module 409 are all packaged in the installation cavity through a transmitter sealing shell 410; the temperature sensor 412 is embedded in the wall of the inner tube 416, and the temperature sensor 412 is electrically connected to the signal module 409 through a wire 411.

[0048] The wireless transmitter assembly 406 integrates the coil 407, the transmitter core tube 408 and the signal module 409, which are tightly sealed by the transmitter sealing shell 410 to ensure that the electronic components are not disturbed by the external environment. The temperature sensor 412 is embedded in the wall of the inner tube 416 to directly sense the temperature change of the heat exchange medium and establish an electrical connection with the signal module 409 through the wire 411.

[0049] The temperature sensor 412 captures temperature changes, converts physical quantities into electrical signals, and sends them to the signal module 409 via the wire 411. After receiving the electrical signals, the signal module encodes them into a digital format and prepares for wireless transmission. The coil 407 and the transmitter core tube 408 combine to generate electromagnetic waves, which carry the encoded temperature information and radiate outward, and are eventually intercepted by the ground receiving station.

[0050] With this arrangement, the temperature sensor 412 can be freed from the constraints of cables, thereby improving deployment flexibility, and is particularly suitable for environments such as deep wells where it is difficult to access cables.

[0051] It should be noted that corresponding positions of the internal temperature measuring components are provided with cover plate sealing grooves and sealing rings 413 and sensor mounting holes and sealing rings 414 for sealing.

[0052] Continue reading Figure 1 and Figure 2 In some embodiments of the present invention, the external temperature measuring component includes an armored optical cable 315, and the armored optical cable 315 is arranged on the outer surface of the heat exchange column string 2 through an optical cable clamp 312, and the distance between two adjacent optical cable clamps 312 is 8m-10m.

[0053] Among them, the use of high-strength materials to coat the optical cable to form armor protection can enhance the ability of the optical cable to resist mechanical damage, which is particularly suitable for stable operation in complex geological environments. The optical cable itself is used as a temperature sensor, which can achieve multi-point temperature measurement over a long distance and cover a large monitoring area.

[0054] The interval of the optical cable clamp 312 is set between 8m and 10m to ensure that the optical cable 315 is stably attached to the outer surface of the heat exchange column string 2 to avoid movement or wear. The armored optical cable 315 is laid along the length of the column to form a dense temperature sensing network to provide comprehensive temperature profile information. The end of the armored optical cable 315 is provided with an optical cable dead plug 317 for plugging.

[0055] Continue reading Figure 2 In some embodiments of the present invention, the heat exchange column string 2 includes a second water intake pipe 316, a first water intake pipe 313 and a pump chamber pipe 309 which are sequentially connected from bottom to top. The length of the second water intake pipe 316 accounts for 1 / 5 of the total length of the heat exchange column string 2, and perforations are provided in the circumferential direction of the bottom column of the second water intake pipe 316.

[0056] The second water intake pipe 316, the first water intake pipe 313 and the pump chamber pipe 309 are all insulated pipes; or, the pump chamber pipe 309 and the first water intake pipe 313 are insulated pipes, and the second water intake pipe 316 is a steel pipe or a PE pipe; the heat exchanger unit 1 is arranged inside the pump chamber pipe 309, and is passed through the cable crossing hole 306 of the wellhead device 5 through the steel wire power cable 318.

[0057] Among them, the second water intake pipe 316 is located at the bottom, occupying one-fifth of the total length of the pipe string, and a perforation area is specially set up to promote water inflow and optimize heat exchange efficiency. The first water intake pipe 313 connects the second water intake pipe 316 and the pump room pipe 309, acting as a transition section. Its insulation design reduces heat loss and maintains a stable water temperature. The pump room pipe 309, as the top part, accommodates the heat exchange unit and the power supply line, and directly contacts the pump room equipment to ensure smooth conversion of heat energy.

[0058] The heat-insulating pipe can be made of a special heat-insulating material, such as the first water intake pipe 313 and the pump chamber pipe 309, which can greatly slow down the heat conduction rate and save energy consumption. The second water intake pipe 316 can be made of different materials according to the environment, such as a heat-insulating pipe, a steel pipe or a PE pipe, which can meet the cost control and take into account the durability and heat absorption capacity. The heat exchange unit 1 is embedded in the pump chamber pipe 309, and is powered by a steel wire power cable 318 to achieve circuit connection with the wellhead device 5 to ensure uninterrupted operation.

[0059] After the reinjected heat exchange medium or geothermal water exchanges heat with the formation or heat storage, it enters the second water intake pipe 316 through the perforated pipe at the bottom of the second water intake pipe 316 or the bottom of the heat exchange pipe string 2, rises through the first water intake pipe 313, is extracted by the heat exchange unit to the heat exchange medium extraction hole 305, and flows into the heat exchanger 9 through the ground heat exchange pipeline 10 to release heat to the user side for heating or power generation. The steel wire power cable 318 not only supplies power, but also carries monitoring and communication functions, realizes remote operation and maintenance, improves the level of automation, and can also assume the function of the lower heat exchange unit.

[0060] Continue reading Figure 2 In some embodiments of the present invention, the heat exchanger unit 1 includes a fishing head 319, a sealing cylinder 320, a sealing rubber cylinder 321, an anchoring slip assembly 322, a deep well high temperature resistant electric submersible pump group 323 and a centralizer 327 connected in sequence from top to bottom.

[0061] The deep well high temperature resistant electric submersible pump group 323 is provided with a pump water inlet 324 and a water outlet. The pump water inlet 324 is located below the sealing rubber cylinder 321, and the water outlet is located above the sealing rubber cylinder 321; a downhole monitor 326 and a protector 325 are provided below the deep well high temperature resistant electric submersible pump group 323. The downhole monitor 326 is electrically connected to the deep well high temperature resistant electric submersible pump group 323 for monitoring the operation of the deep well high temperature resistant electric submersible pump group 323, and the protector 325 is used to protect the motor 328 of the electric pump.

[0062] Among them, the salvage head 319 is a top component, which is convenient for lifting and positioning to ensure the overall stability of the heat exchanger unit. The sealing cylinder 320 is mainly used to ensure the pressure-resistant seal of the cable connection position. The sealing rubber cylinder 321 plays an isolation role, controls the flow direction of the liquid, and guides the geothermal water to enter and exit the pump group through a specific channel. The anchoring slip assembly 322 fixes the pump group in a predetermined position to resist the impact of high-speed water flow and maintain operational balance. The deep well high-temperature resistant submersible pump group 323 is the main power source, including a motor and an impeller, which is adapted to high-temperature environments and efficiently pumps geothermal liquids. The protector 325 prevents electrical faults such as overload and short circuit, and protects the safe operation of the motor. The downhole monitor 326 continuously monitors the working status of the pump group, feedbacks data in real time, and warns of potential problems.

[0063] Geothermal water enters the pump group through the pump inlet 324 below the sealing rubber cylinder 321, flows through the impeller flow channel for pressurization, and the pressurized hot water gushes upward through the outlet above the sealing rubber cylinder 321 until it reaches the surface or the heat energy conversion system. The downhole monitor 326 simultaneously records various parameters of the pump group and uploads them to the ground control center to realize remote scheduling and emergency response.

[0064] Continue reading Figure 2 In some embodiments of the present invention, the heat exchanger unit 1 also includes a pressure sensor 310, which is arranged on the upper and lower end surfaces of the sealing rubber cylinder 321. The pressure sensor 310 is connected to the downhole monitor 326 through a lead cable 311 to monitor the pressure at both ends of the sealing rubber cylinder 321.

[0065] The pressure sensor 310 is arranged at the upper and lower ends of the setting rubber cylinder 321 to capture the data of pressure changes. The data of pressure changes is connected to the downhole monitor 326 through the lead cable 311, and the pressure value is transmitted back to the surface control system in real time. It is used to reflect the flow state of the fluid, detect signs of blockage or leakage, and prevent potential accidents.

[0066] Continue reading Figure 1 and Figure 2 In some embodiments of the present invention, the wellhead device 5 includes a casing head body, a lifting flange 307 and a completion flange connected in sequence from bottom to top; the casing head body defines a first inner cavity, the upper end of the first inner cavity is sealed and connected to a heat exchange tubing string hanger 302, and the lower end of the first inner cavity is sealed and connected to a casing hanger 304.

[0067] The raised flange 307 defines a second inner cavity, which is connected to the heat exchange tubing string hanger 302; the heat exchange medium production hole 305 is arranged on the completion flange, and the completion flange is also provided with a cable through hole 306 and an optical cable through hole 301; the heat exchange medium injection hole 303 is arranged on the side wall of the raised flange 307 and extends to the through casing hanger 304.

[0068] The casing head body constitutes the main frame, and is provided with a first inner cavity, which is sealed and connected to the heat exchange column string hanger 302 and the casing hanger 304 respectively, to ensure fluid circulation and structural stability. The raised flange 307 defines the second inner cavity, which receives the heat exchange medium from underground and has an interface for docking with external equipment. The completion flange is a top closure, which integrates various functional openings, including the heat exchange medium extraction hole 305, the cable crossing hole 306 and the optical cable crossing hole 301, to ensure the unimpeded passage of multiple pipelines.

[0069] It should be noted that in the process of hot development, for abandoned oil and gas wells, oil and gas may still escape due to the long-term recovery of the formation. In order to prevent the risk of oil and gas being produced from the perforation section, the oil and gas production perforation section needs to be plugged. This is not necessary for geothermal wells.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An open type heat exchange device for the development of medium-deep geothermal wells, characterized in that: include: A wellhead device is arranged at the wellhead of the heat exchange well, wherein the wellhead device is provided with a heat exchange medium production hole and a heat exchange medium injection hole, and the heat exchange medium production hole and the heat exchange medium injection hole are both connected to the heat exchanger circulation through a ground heat exchange pipeline; A main body component is suitable for extending into the formation, and the main body component includes a heat exchange string, a casing and a heat exchange unit. The heat exchange string and the casing are both arranged at the bottom of the wellhead device. A heat exchange production channel is constructed inside the heat exchange string, and the heat exchange production channel is connected to the heat exchange medium production hole. A downhole reinjection channel is constructed between the heat exchange string and the casing, and the downhole reinjection channel is connected to the heat exchange medium injection hole; The temperature monitoring device is arranged between the heat exchange column string and the casing, and is used to monitor the temperature of the heat exchange medium at different positions inside and outside the heat exchange column string.

2. The open type heat exchange device for developing medium-deep geothermal wells according to claim 1, characterized in that: The temperature monitoring device includes an insulated temperature measuring short section and an external temperature measuring component. The insulated temperature measuring short section is connected to the pipe section of the heat exchange column string and is used to monitor the temperature of the corresponding position inside the heat exchange column string; the external temperature measuring component is arranged between the heat exchange column string and the casing and is used to monitor the temperature of the corresponding position outside the heat exchange column string.

3. The open type heat exchange device for developing medium-deep geothermal wells according to claim 2, characterized in that: The thermal insulation temperature measuring short section includes a mounting component and an internal temperature measuring component. The mounting component is provided with threads near both ends, and the threads cooperate with the corresponding pipe section threads of the heat exchange column string. The internal temperature measuring component is arranged inside the mounting component to monitor the temperature of the corresponding position inside the heat exchange column string.

4. The open type heat exchange device for developing medium-deep geothermal wells according to claim 3, characterized in that: The installation component includes an inner tube, an insulation layer and an outer tube which are stacked in sequence from the inside to the outside. The inner tube is welded to the inner wall of the outer tube and defines a sealed cavity between the inner tube and the outer tube. The insulation layer is located in the sealed cavity. The insulation layer is provided with an installation cavity. The outer tube is provided with an opening connected to the installation cavity. The internal temperature measuring component is provided in the installation cavity. The position of the opening is sealed and connected with a protective shell by fastening bolts.

5. The open type heat exchange device for developing medium-deep geothermal wells according to claim 4, characterized in that: The internal temperature measurement component includes a wireless transmitter assembly and a temperature sensor; The wireless transmitter assembly includes an electrically connected coil, a transmitter core tube and a signal module, and the coil, the transmitter core tube and the signal module are all packaged in the installation cavity through a transmitter sealing shell; The temperature sensor is embedded in the tube wall of the inner tube, and the temperature sensor is electrically connected to the signal module through a wire.

6. The open type heat exchange device for developing medium-deep geothermal wells according to claim 2, characterized in that: The external temperature measuring component includes an armored optical cable, which is arranged on the outer surface of the heat exchange column string through an optical cable clamp, and the distance between two adjacent optical cable clamps is 8m-10m.

7. The open type heat exchange device for developing medium-deep geothermal wells according to any one of claims 1 to 6, characterized in that: The heat exchange pipe string string comprises a second water intake pipe, a first water intake pipe and a pump chamber pipe which are sequentially connected from bottom to top, the length of the second water intake pipe accounts for 1 / 5 of the total length of the heat exchange pipe string string, and a perforation is provided in the circumferential direction of the bottom pipe string of the second water intake pipe; The second water intake pipe, the first water intake pipe and the pump chamber pipe are all heat-insulating pipes; or the pump chamber pipe and the first water intake pipe are heat-insulating pipes, and the second water intake pipe is a steel pipe or a PE pipe; The heat exchange unit is arranged inside the pump chamber pipe and is passed through the cable passing hole of the wellhead device through a steel wire power cable.

8. The open type heat exchange device for developing medium-deep geothermal wells according to any one of claims 1 to 6, characterized in that: The heat exchange unit comprises a fishing head, a sealing cylinder, a sealing rubber cylinder, an anchoring slip assembly, a deep well high temperature resistant electric submersible pump unit and a centralizer which are connected in sequence from top to bottom; The deep well high temperature resistant electric submersible pump group is provided with a pump water inlet and a water outlet, the pump water inlet is located below the setting rubber cylinder, and the water outlet is located above the setting rubber cylinder; A downhole monitor and a protector are provided below the deep well high temperature resistant submersible pump group. The downhole monitor is electrically connected to the deep well high temperature resistant submersible pump group and is used to monitor the operation of the deep well high temperature resistant submersible pump group. The protector is used to protect the motor of the deep well high temperature resistant submersible pump group.

9. The open type heat exchange device for developing medium-deep geothermal wells according to claim 8, characterized in that: The heat exchange unit also includes a pressure sensor, which is arranged on the upper and lower end surfaces of the sealing rubber cylinder. The pressure sensor is connected to the downhole monitor through a lead cable and is used to monitor the pressure at both ends of the sealing rubber cylinder.

10. The open type heat exchange device for developing medium-deep geothermal wells according to any one of claims 1 to 6, characterized in that: The wellhead device comprises a casing head body, a riser flange and a completion flange which are sequentially connected from bottom to top; The casing head body defines a first inner cavity, the upper end of the first inner cavity is sealedly connected to a heat exchange column string hanger, and the lower end of the first inner cavity is sealedly connected to a casing hanger; The raised flange defines a second inner cavity, which is connected to the heat exchange tubing string hanger; the heat exchange medium production hole is arranged on the completion flange, and the completion flange is also provided with a cable through hole and an optical cable through hole; the heat exchange medium injection hole is arranged on the side wall of the raised flange and extends to penetrate the casing hanger.

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