Core chamber for in-situ hydrate preservation based on gravity heat pipe

Abstract

The application discloses a core cabin of a natural gas hydrate in-situ heat and pressure preserving coring device based on a gravity heat pipe, and belongs to the technical field of natural gas hydrate exploitation, and comprises a core cabin outer pipe assembly, wherein the core cabin outer pipe assembly comprises a first outer pipe, a second outer pipe, a third outer pipe, a fifth outer pipe, a sixth outer pipe and a seventh outer pipe which are sequentially connected from top to bottom, a chip removal groove is threadedly connected to the bottom of the seventh outer pipe, and a drill bit is threadedly connected to the bottom of the chip removal groove; the application uses thermoelectric refrigeration and heat pipe heat transfer principles to integrate a refrigeration mechanism on a hydrate coring device, breaks through the heat preservation technical bottleneck existing in conventional natural gas hydrate coring equipment and technology, and the integrated heat pipe enhanced heat transfer system solves the heat dissipation problem of the refrigeration mechanism of the coring device, so that the core in the core cabin of the coring device can keep the in-situ temperature, original and faithful samples are provided for reservoir evaluation and basic physical property research, and new equipment and technology are provided for marine natural gas hydrate heat and pressure preserving coring.

Description

Technical Field

[0001] This invention belongs to the field of natural gas hydrate extraction technology, and particularly relates to a core chamber of a gravity heat pipe-based in-situ heat-insulating and pressure-maintaining core sampler for natural gas hydrates. Background Technology

[0002] Due to the extremely complex formation mechanism and geological background of natural gas hydrate reservoirs, in-depth research is still needed on pre-extraction reserve assessment, reservoir changes during extraction, and assessment of potential geological hazards. Obtaining authentic core samples of hydrate formations is a major prerequisite for resource identification, reservoir evaluation, improving extraction efficiency, studying reservoir deformation, and ensuring operational safety. Deep-sea natural gas hydrates exist at low temperatures and high pressures, and are prone to phase transitions after environmental changes. Therefore, to obtain natural gas hydrates in their in-situ environment, it is necessary to maintain both temperature (2-20℃) and pressure (typically 2.5 to 11 MPa). However, current heat-insulating and pressure-insulating coring equipment can only achieve a certain success rate of pressure-insulating coring, and cannot maintain the in-situ temperature and pressure of natural gas hydrates, resulting in irreversible distortion of natural gas hydrate samples. Summary of the Invention

[0003] The purpose of this invention is to provide a core chamber for an in-situ heat-insulating and pressure-maintaining coring device for natural gas hydrates based on a gravity heat pipe, so as to solve the problems existing in the prior art.

[0004] To achieve the above objectives, the present invention provides the following solution: The present invention provides a core chamber for an in-situ heat-insulated and pressure-maintaining coring device for natural gas hydrates based on a gravity heat pipe, comprising:

[0005] The core chamber outer tube assembly includes a first outer tube, a second outer tube, a third outer tube, a fifth outer tube, a sixth outer tube, and a seventh outer tube connected sequentially from top to bottom. The bottom of the seventh outer tube is threaded with a chip removal groove, and the bottom of the chip removal groove is threaded with a drill bit.

[0006] A central rod assembly is located inside the outer tube assembly of the core chamber. The central rod assembly includes a first central rod, a third central rod, a fourth central rod, and a fifth central rod connected sequentially from top to bottom. A second central rod is slidably connected inside the first central rod. The first central rod and the second central rod are interconnected. A heat preservation mechanism is provided at the bottom of the fourth central rod, and a piston is provided inside the fourth central rod.

[0007] The core tube assembly includes a rotating bearing disposed between the third outer tube and the fifth outer tube, the rotating bearing having a small bearing inside, the fifth outer tube having a first sliding ring and a second sliding ring respectively, the first sliding ring and the second sliding ring having a core tube internally threadedly connected, the second sliding ring having a ball bearing inside, and the bottom of the core tube having a core clamping claw.

[0008] Preferably, the heat preservation mechanism includes a heat-conducting block disposed inside the fourth central rod, a thermoelectric cooling plate disposed outside the heat-conducting block, and the fifth central rod is located outside the fourth central rod.

[0009] Preferably, the third outer tube is coated with a thermal insulation material.

[0010] Preferably, the piston is provided with a first double-layer sealing ring.

[0011] Preferably, the fourth central rod is provided with an internal heat pipe.

[0012] Preferably, a clamping hoop is fixedly connected to the second outer tube, and a capture ring is snapped into the clamping hoop, with the first central rod disposed inside the capture ring.

[0013] Preferably, the small bearing is embedded inside the internal assembly of the capture ring.

[0014] Preferably, the fifth outer tube is provided with a second double-layer sealing ring.

[0015] This invention discloses the following technical effects: This invention integrates a refrigeration mechanism into a hydrate core sampler using thermoelectric refrigeration and heat pipe heat transfer principles, breaking through the insulation technology bottleneck of conventional natural gas hydrate core sampling equipment and technology. Furthermore, the integrated heat pipe enhanced heat transfer system of this invention solves the heat dissipation problem of the core sampler's refrigeration mechanism, enabling the core in the core chamber of the core sampler to maintain its in-situ temperature, providing original and authentic samples for reservoir assessment and basic physical property research, and providing new equipment and technology for heat preservation and pressure retention core sampling of marine natural hydrates. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0017] Figure 1 This is a schematic diagram of the initial state of the thermoelectric-based heat-insulating and pressure-maintaining natural gas hydrate core chamber of the present invention.

[0018] Figure 2 This is a schematic diagram of the core-taking state of the thermoelectric-based, pressure-maintaining natural gas hydrate core chamber of the present invention after core sampling.

[0019] Figure 3 for Figure 1 A magnified view of a portion of A1;

[0020] Figure 4 for Figure 2 A magnified view of a portion of A2;

[0021] Figure 5 for Figure 1 A magnified view of part B1;

[0022] Figure 6 for Figure 2 A magnified view of part B2;

[0023] Figure 7 for Figure 2 A magnified view of part B3 in the image.

[0024] Figure 8 for Figure 1 A magnified view of part C;

[0025] Figure 9 This is a schematic diagram of the insulation mechanism;

[0026] Figure 10 This is a schematic diagram of the pressure holding controller.

[0027] Figure 11 This is a schematic diagram of the thermal insulation and pressure preservation structure of the natural gas hydrate core chamber based on the thermoelectric principle of the present invention;

[0028] Figure label:

[0029] 411. First outer tube; 412. Second outer tube; 413. Third outer tube; 414. Thermal insulation coating layer; 415. Fifth outer tube; 416. Sixth outer tube; 417. Seventh outer tube; 418. Chip removal groove; 419. Drill bit; 421. First center rod; 422. Second center rod; 423. Third center rod; 424. Internal heat pipe of the center rod; 425. Fourth center rod; 426. Piston; 427. First double-layer sealing ring ; 428. Heat-conducting block; 429. Thermoelectric cooling element; 4210. Fifth center rod; 4211. Outer shell; 431. Clamping hoop; 432. Capturing ring; 433. First sliding ring; 434. Second sliding ring; 435. Rotary bearing; 436. Second double-layer sealing ring; 437. Small bearing; 438. Spring; 439. Pressure holding controller; 4310. Core tube; 4311. Core chuck; 4312. Internal components of the capturing ring. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Reference Figures 1-11 As shown, this embodiment provides a thermoelectrically based, pressure- and heat-insulating natural gas hydrate core chamber, including...

[0033] The core chamber outer tube assembly includes a first outer tube 411, a second outer tube 412, a third outer tube 413, a fifth outer tube 415, a sixth outer tube 416, and a seventh outer tube 417 connected sequentially from top to bottom. The bottom of the seventh outer tube 417 is threadedly connected to a chip removal groove 418, and the bottom of the chip removal groove 418 is threadedly connected to a drill bit 419.

[0034] The central rod assembly is located inside the outer tube assembly of the core chamber. The central rod assembly includes a first central rod 421, a third central rod 423, a fourth central rod 425, and a fifth central rod 4210 connected sequentially from top to bottom. A second central rod 422 is slidably connected inside the first central rod 421. The first central rod 421 and the second central rod 422 are interconnected. The bottom of the fourth central rod 425 is provided with a heat preservation mechanism, and a piston 426 is provided inside the fourth central rod 425.

[0035] The core tube 4310 assembly includes a rotating bearing 435 disposed between the third outer tube 413 and the fifth outer tube 415. The rotating bearing 435 contains a small bearing 437. The fifth outer tube 415 contains a first sliding ring 433 and a second sliding ring 434. The core tube 4310 is threadedly connected to the first sliding ring 433 and the second sliding ring 434. The second sliding ring 434 contains a ball. The bottom of the core tube 4310 is provided with a core clamp 4311.

[0036] This invention integrates a cooling mechanism onto a hydrate core sampler using thermoelectric refrigeration and heat pipe principles. This overcomes the challenge of applying complex traditional refrigeration structures to extremely confined downhole spaces. Furthermore, the heat pipe addresses heat dissipation issues and improves the axial temperature uniformity of the core. This provides a new approach for deep-sea hydrate core sampling.

[0037] The first outer tube 411, the second outer tube 412, the third outer tube 413, the fifth outer tube 415, the sixth outer tube 416 and the seventh outer tube 417 are connected by threads and sealed with sealing rings. The thermal insulation material coating layer 414 is applied to the surface of the third outer tube 413. The seventh outer tube 417, the drain groove and the drill bit 419 are connected by threaded sealing.

[0038] The first center rod 421, the third center rod 423, the fourth center rod 425, and the fifth center rod 4210 are connected by threads and sealed with sealing rings. The first center rod 421 and the second center rod 422 can slide together, and there are gaps between them to allow drilling fluid to flow. Before coring, the fourth center rod 425 is pre-charged with air to push the piston 426 to its lowest point. The first double-layer sealing ring 427 is fitted on the outside of the fourth center rod 425. The fifth center rod 4210 is used to seal the heat-conducting block 428 placed in the fourth center rod 425. The outer shell 4211 is used to seal the outside of the fifth center rod 4210.

[0039] The design is further optimized so that the insulation mechanism includes a heat-conducting block 428 disposed within the fourth central rod 425, a thermoelectric cooling element 429 disposed outside the heat-conducting block 428, and a fifth central rod 4210 located outside the fourth central rod 425. An auxiliary heat pipe is disposed within the fourth central rod 425.

[0040] The clamping hoop 431 is fixed to the second outer tube 412 and holds the capture ring 432 in place. The bearing ring of the rotating bearing 435 is held between the third outer tube 413 and the fifth outer tube 415, and the ball bearing is embedded in the second sliding ring 434, which is the bearing ring of the small bearing 437. The small bearing 437 is embedded inside the internal assembly 4312 of the capture ring. One end of the spring 438 rests against the end face of the fifth outer tube 415, and the other end rests against the internal assembly 4312 of the capture ring.

[0041] The design is further optimized by providing an insulation material coating layer 414 on the outside of the third outer tube 413.

[0042] The design was further optimized by adding a first double-layer sealing ring 427 to the piston 426.

[0043] The design has been further optimized by installing an internal heat pipe 424 on the fourth center rod 425.

[0044] The scheme is further optimized by fixing a clamping hoop 431 to the second outer tube 412, and a capture ring 432 is snapped into the clamping hoop 431. The capture ring 432 is provided with a first central rod 421.

[0045] The design has been further optimized by installing a second double-layer sealing ring 436 inside the fifth outer tube 415.

[0046] When the core sampler is lowered into the bottom hole assembly, the drilling vessel on the surface provides drilling fluid to drive the core sampler. The drilling fluid drives the screw motor in the core sampler, which in turn drives the outer casing assembly downwards. The flow direction of the drilling fluid in the core chamber is as follows: Figure 1 In the direction of the middle arrow, it mainly flows in the gap between the outer tube assembly and the center rod assembly. After the drilling fluid reaches the drill bit 419, it flows out of the core extractor from the drill bit 419, carrying the cuttings upward along the cuttings discharge groove 418.

[0047] As the outer tube assembly is driven downwards by the drilling fluid to drill for core extraction, and the center rod assembly has a hexagonal cross-section to prevent rotation, relative rotation occurs between the outer tube assembly and the center rod assembly, achieved by the rotary bearing 435. Furthermore, as the outer tube assembly feeds downwards, relative movement occurs between the center rod assembly and the outer tube assembly, achieved by the small bearing 437 (since the rotary bearing 435 is fixed, the core tube assembly and the outer tube assembly, consisting of the first sliding ring 433, the second sliding ring 434, the rotary bearing 435, the second double-layer sealing ring 436, and the small bearing 437, are relatively stationary, while the core moves relative to the center rod assembly). At this time, the core gradually enters the core tube. When the small bearing 437 moves into the groove of the fourth center rod 425, the bearing ring of the small bearing 437 is driven by the center rod assembly to move relative to the second sliding ring 434, and the rotating bearing 435 also falls into the groove corresponding to the small bearing 437. The core tube assembly and the outer tube assembly composed of the first sliding ring 433, the second sliding ring 434, the rotating bearing 435, the second double-layer sealing ring 436 and the small bearing 437 are unlocked.

[0048] At this point, the drilling fluid is stopped, and the center rod assembly of the core extractor is pulled up via a rope, forming a... Figure 2 The state shown is as follows. At this time, the second sliding ring 434 and the fourth central rod 425 achieve end face sealing through the second double-layer sealing ring 436, and the second sliding ring 434 and the fifth outer tube 415 also achieve end face sealing through the second double-layer sealing ring 436. At the bottom, the core tube assembly is pulled upwards by the central rod assembly (during the lifting process, the internal component 4312 of the capture ring is lifted together by friction). The valve cover of the pressure holding controller 439 closes with gravity, and its end face is sealed by a single-layer sealing ring. (At this time, after the internal component 4312 of the capture ring is lifted to a certain height, the spring 438 is compressed to its limit value, and the internal component 4312 of the capture ring then springs down, pressing on the pressure holding controller 439, making the sealing reliability of the pressure holding controller 439 higher). At the same time, because the fourth central rod 425 is pre-charged with air energy, it can maintain the pressure inside the chamber and regulate the pressure fluctuation inside the chamber. Because the fourth center rod 425 integrates a thermoelectric cooling element 429, power is supplied to the thermoelectric cooling element 429 through internal cables of the center rod assembly to cool the rock core. At the same time, the heat generated by the hot surface is diverted through the heat pipe 424 inside the center rod. This achieves heat preservation and pressure maintenance.

[0049] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0050] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A core chamber for an in-situ insulated and pressure-maintaining coring unit for natural gas hydrates based on a gravity heat pipe, characterized in that: include The core chamber outer tube assembly includes a first outer tube (411), a second outer tube (412), a third outer tube (413), a fifth outer tube (415), a sixth outer tube (416), and a seventh outer tube (417) connected sequentially from top to bottom. The bottom of the seventh outer tube (417) is threaded with a chip removal groove (418), and the bottom of the chip removal groove (418) is threaded with a drill bit (419). The central rod assembly is located inside the outer tube assembly of the core chamber. The central rod assembly includes a first central rod (421), a third central rod (423), a fourth central rod (425), and a fifth central rod (4210) connected sequentially from top to bottom. A second central rod (422) is slidably connected inside the first central rod (421). The first central rod (421) and the second central rod (422) are interconnected. The bottom of the fourth central rod (425) is provided with a heat preservation mechanism. A piston (426) is provided inside the fourth central rod (425). Before core extraction, the fourth central rod (425) is pre-filled with air to push the piston (426) to the bottom. A core tube assembly, comprising a rotating bearing (435) disposed between the third outer tube (413) and the fifth outer tube (415), wherein a small bearing (437) is provided inside the rotating bearing (435), and a first sliding ring (433) and a second sliding ring (434) are respectively provided inside the fifth outer tube (415). The first sliding ring (433) and the second sliding ring (434) are internally threaded to a core tube (4310), wherein a ball is provided inside the second sliding ring (434), and a core chuck (4311) is provided at the bottom of the core tube (4310). The heat preservation mechanism includes a heat-conducting block (428) disposed inside the fourth central rod (425), a thermoelectric cooling chip (429) disposed outside the heat-conducting block (428), and the fifth central rod (4210) located outside the fourth central rod (425); The fourth central rod (425) is provided with an internal heat pipe (424), and the heat generated by the hot surface of the thermoelectric cooling chip (429) is conducted away by the internal heat pipe (424).

2. The core chamber of the in-situ heat-insulating and pressure-maintaining coring machine for natural gas hydrates based on gravity heat pipes according to claim 1, characterized in that: The third outer tube (413) is provided with a thermal insulation material coating layer (414).

3. The core chamber of the in-situ heat-insulated and pressure-maintaining coring machine for natural gas hydrates based on gravity heat pipes according to claim 1, characterized in that: The piston (426) is provided with a first double-layer sealing ring (427).

4. The core chamber of the in-situ heat-insulated and pressure-maintaining coring machine for natural gas hydrates based on gravity heat pipes according to claim 1, characterized in that: A clamping hoop (431) is fixedly connected to the second outer tube (412), and a capture ring (432) is snapped into the clamping hoop (431). The first central rod (421) is provided inside the capture ring (432).

5. The core chamber of the in-situ heat-insulated and pressure-maintaining coring machine for natural gas hydrates based on gravity heat pipes according to claim 1, characterized in that: The small bearing (437) is embedded inside the internal component (4312) of the capture ring.

6. The core chamber of the in-situ heat-insulated and pressure-maintaining coring machine for natural gas hydrates based on gravity heat pipes according to claim 1, characterized in that: The fifth outer tube (415) is provided with a second double-layer sealing ring (436).

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