Natural gas hydrate freezing sampling device

Abstract

The invention relates to the technical field of freezing sampling equipment, and particularly discloses a natural gas hydrate freezing sampling device which comprises a freezing catalyst storage pipe, a cold source storage pipe and a core barrel, the cold source storage pipe is coaxially arranged in an inner cavity of the freezing catalyst storage pipe, and an overflow port is formed in the upper end of the cold source storage pipe; an annular frozen catalyst storage cavity for storing a frozen catalyst is reserved between the cold source storage pipe and the frozen catalyst storage pipe; a smooth cavity and an internal thread cavity are formed in an inner cavity of the cold source storage pipe from top to bottom. The upper end of the core barrel is connected with a piston head through a connecting rod, the piston head is slidably arranged in the smooth cavity, and a cold source is stored between the piston head and the inner top of the cold source storage pipe; an external thread part is arranged on the outer wall of the core barrel and is meshed with the internal thread cavity; the power part is used for driving the frozen catalyst storage pipe to rotate; the natural gas hydrate sampling device realizes heat-preservation and pressure-preservation treatment on the natural gas hydrate during sampling, and keeps the original state of a sample to the greatest extent after sampling is completed.

Description

Technical Field

[0001] The invention relates to the technical field of freezing sampling equipment, and in particular to a natural gas hydrate freezing sampling device. Background Art

[0002] Natural gas hydrates are mainly distributed in seafloor sediments at the edge of the ocean and in the permafrost layer of the high-altitude permafrost on land. Drilling sampling is the most direct way to identify natural gas hydrates and is also a necessary means to verify the results of other survey methods. By coring, we can intuitively observe and understand the rock type, structure, and structural characteristics of the crust without destroying the overall formation, as well as detect its oil, gas, and water production characteristics. Through laboratory testing and analysis, we can clearly know the distribution, stability, and various physical properties of natural gas hydrates, which provides a basis for formulating reasonable development plans and production increase measures.

[0003] Since natural gas hydrates can only exist stably under certain temperature and pressure, heat preservation and pressure maintenance are required during coring. There are currently two main methods for true sampling, one is heat preservation and pressure maintenance sampling, and the other is bottom hole freezing sampling. Heat preservation and pressure maintenance sampling mainly uses ball valves and flap valves to maintain the pressure of the core tube, and uses insulation materials for passive insulation. Due to its complex mechanical structure, the sealing cannot be guaranteed and the high heat conduction during drilling, the failure rate of coring is relatively high.

[0004] Bottom hole cryogenic sampling is a method of suppressing the decomposition of natural gas hydrates by low temperature. After drilling is completed, a cooling catalyst is injected into the freezing chamber through a cold source control device. When the cold source contacts the cooling catalyst, it absorbs a large amount of heat and reduces the temperature of the core tube to a low temperature zone, ensuring that the natural gas hydrates will not decompose during the lifting process. This method has a high success rate for coring and ensures that the substance will not change, so a device for cryogenic sampling of natural gas hydrates is needed. Summary of the invention

[0005] The object of the present invention is to provide a natural gas hydrate freezing sampling device, which realizes the heat preservation and pressure preservation treatment of natural gas hydrate when sampling it, and after the sampling is completed, the original state of the sample is maintained to the greatest extent.

[0006] The present invention is realized by the following technical scheme: a natural gas hydrate freezing sampling device is arranged in a drill pipe with a drill bit connected at the bottom, and comprises a connecting seat, a single-action component and a freezing sampler which are sequentially connected from top to bottom;

[0007] The freezing sampler comprises a freezing catalyst storage tube, a cold source storage tube and a core tube, wherein the upper end of the freezing catalyst storage tube is sealed and connected to the single-action assembly;

[0008] The cold source storage tube is coaxially arranged in the inner cavity of the frozen catalyst storage tube, the lower end of the cold source storage tube is sealed with the frozen catalyst storage tube, the upper end of the cold source storage tube is sealed and a gap is left between the inner top of the frozen catalyst storage tube, and the upper end of the cold source storage tube is provided with an overflow port;

[0009] An annular frozen catalyst storage cavity for storing frozen catalyst is left between the cold source storage tube and the frozen catalyst storage tube, and the overflow port is connected to the inner cavity of the cold source storage tube and the frozen catalyst storage cavity respectively;

[0010] The inner cavity of the cold source storage tube is respectively provided with a smooth cavity and an internal thread cavity from top to bottom; the upper end of the core tube is connected to a piston head through a connecting rod, the piston head is slidably placed in the smooth cavity, and a cold source is stored between the piston head and the inner top of the cold source storage tube; the outer wall of the core tube is provided with an external thread portion, and the external thread portion is meshed with the internal thread cavity;

[0011] It also includes a power piece, which is used to drive the frozen catalyst storage tube to rotate.

[0012] Further, the single-action assembly includes a sleeve, a docking head and a ratchet mechanism, the upper end of the sleeve is connected to the connecting seat, the docking head is rotatably placed in the sleeve, and the lower end of the docking head is connected to the frozen catalyst storage tube;

[0013] The ratchet mechanism comprises a ratchet ring, a driving ring and a ratchet pawl, wherein the ratchet ring is embedded in the sleeve, and a plurality of ratchet teeth are annularly arranged in the inner cavity of the ratchet ring;

[0014] The driving ring is sleeved on the docking head, and a plurality of limiting grooves are arranged in an annular array on the driving ring. The pawl is rotatably arranged in the limiting groove, and the pawl extends out of the limiting groove and meshes with the ratchet under the action of the torsion spring.

[0015] Furthermore, a screw is coaxially connected to the upper end of the sleeve, and the screw is coaxially placed in the connecting seat and meshed with the connecting seat.

[0016] Furthermore, the power component includes a water turbine, a drive sleeve and a connecting sleeve, the connecting sleeve is coaxially rotatably connected to the connecting seat, the drive sleeve is coaxially connected to the connecting sleeve, the drive sleeve is sleeved on the screw, and the drive sleeve is key-connected to the screw.

[0017] Furthermore, a plurality of slurry discharge grooves are arranged in a circular array in the internal thread cavity, and the slurry discharge grooves are arranged vertically;

[0018] A slurry discharge port is provided through the top of the core tube.

[0019] Furthermore, a filling port is provided through the top of the frozen catalyst storage tube, and a sealing plug is provided on the filling port.

[0020] Furthermore, a pressure valve is provided on the overflow port.

[0021] Furthermore, a retaining ring and a retaining spring are sequentially connected to the lower end of the core tube;

[0022] A retaining spring seat is arranged in the drill pipe.

[0023] Furthermore, a plurality of centralizers are arranged in an annular array inside the drill pipe, and the centralizers are in sliding contact with the frozen catalyst storage tube.

[0024] Furthermore, a plurality of rubber sealing rings are vertically spaced apart on the piston head.

[0025] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0026] 1. The external threaded portion of the core tube is meshed with the internal threaded cavity of the cold source storage tube. The power part drives the frozen catalyst storage tube to rotate, which drives the cold source storage tube to rotate relative to the core tube, so that the cold source storage tube moves downward relative to the core tube until it wraps the entire core tube. At the same time, the piston head moves upward in the smooth cavity, and the cold source immediately enters the frozen catalyst storage cavity. After mixing with the frozen catalyst, the core tube and its core sample are frozen.

[0027] 2. The single-action mechanism will not drive the frozen catalyst storage tube to rotate when the drill pipe is drilling in the early stage. When the core sample needs to be frozen, the pressure supply of the drilling fluid is increased to drive the water turbine to rotate. The water turbine drives the driving sleeve to rotate counterclockwise, driving the screw to withdraw from the connecting seat and move downward. At the same time, the frozen catalyst storage tube is driven to rotate through the single-action mechanism, and finally the core sample is frozen and sampled with heat preservation and pressure maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A schematic diagram of the internal structure of a natural gas hydrate freezing sampling device provided by the present invention;

[0030] Figure 2 for Figure 1 Schematic diagram of the structure of the section at AA;

[0031] Figure 3 for Figure 1 A magnified schematic diagram of the structure at B in the middle;

[0032] Icons: 1. Drill bit, 2. Drill pipe, 3. Connecting seat, 4. Single-action assembly, 41. Casing, 42. Butt joint, 43. Ratchet mechanism, 431. Ratchet ring, 4311. Ratchet, 432. Drive ring, 4321. Limiting groove, 433. Paw, 5. Cryogenic sampler, 51. Cryogenic catalyst storage tube, 511. Cryogenic catalyst storage chamber, 512. Filling port, 513. Sealing plug, 52. Cold source Storage tube, 521, overflow port, 522, smooth cavity, 523, internal thread cavity, 524, slurry discharge groove, 525, pressure valve, 53, core tube, 531, external thread part, 54, piston head, 541, connecting rod, 55, rubber sealing ring, 6, power part, 61, water turbine, 62, driving sleeve, 63, connecting sleeve, 7, screw, 8, retaining ring, 9, retaining ring, 10, retaining ring seat, 11, centralizer. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0035] Reference Figures 1 to 3 As shown, this embodiment provides a natural gas hydrate freezing sampling device, which is arranged in a drill pipe 2 with a drill bit 1 connected to the bottom, and includes a connecting seat 3, a single-action component 4 and a freezing sampler 5 connected in sequence from top to bottom; a hanging ring is arranged on the upper end of the connecting seat 3, and the hanging ring is hung on the hanging ring support inside the drill pipe 2, which is used for positioning the entire freezing sampling device and the drill pipe 2, and a spring-cage mechanism and a fishing spear are connected to the upper end of the connecting seat 3 in sequence, and the entire inner tube assembly is lowered into place by the fishing device, so that the entire freezing sampling device reaches the bottom of the hole, and the entire inner tube assembly and the drill pipe 2 are kept in a fixed position unchanged by the cooperation of the spring-cage mechanism and the hanging ring.

[0036] More specifically, Figure 1 and Figure 3As shown, the freezing sampler 5 includes a freezing catalyst storage tube 51, a cold source storage tube 52 and a core tube 53, and the upper end of the freezing catalyst storage tube 51 is sealed and connected to the single-action component 4;

[0037] A cold source storage tube 52 is coaxially arranged in the inner cavity of the frozen catalyst storage tube 51. The lower end of the cold source storage tube 52 is sealed with the frozen catalyst storage tube 51. The upper end of the cold source storage tube 52 is sealed and a gap is left between the inner top of the frozen catalyst storage tube 51. An overflow port 521 is arranged at the upper end of the cold source storage tube 52.

[0038] An annular frozen catalyst storage cavity 511 for storing frozen catalyst is left between the cold source storage tube 52 and the frozen catalyst storage tube 51, and an overflow port 521 is connected to the inner cavity of the cold source storage tube 52 and the frozen catalyst storage cavity 511 respectively; a pressure valve 525 is arranged on the overflow port 521. The liquid cold source stored in the cold source storage tube 52 is squeezed and discharged from the pressure valve 525, and then enters the frozen catalyst storage tube 51. Usually, the frozen catalyst is dry ice and the cold source is liquid nitrogen. A filling port 512 is arranged through the top of the frozen catalyst storage tube 51, and a sealing plug 513 is arranged on the filling port 512.

[0039] When implementing it, Figure 1 and Figure 3 As shown, the outer tube assembly is lowered, and before assembling the inner tube assembly, the sealing plug 513 and the pressure valve 525 are first pulled out, and a sufficient amount of liquid nitrogen is first added to the cold source storage tube 52, and then the pressure valve 525 is inserted into the overflow port 521. The pressure valve 525 is used to prevent the loss of the previous cold source, and then the freezing catalyst dry ice is added to the freezing catalyst storage cavity 511 through the filling port 512, and then the sealing plug 513 is inserted into the filling port 512 to prevent the freezing catalyst from being contaminated or lost.

[0040] More specifically, Figure 3 As shown, the inner cavity of the cold source storage tube 52 is respectively provided with a smooth cavity 522 and an internal thread cavity 523 from top to bottom; the upper end of the core tube 53 is connected to the piston head 54 through a connecting rod 541, and the piston head 54 is slidably placed in the smooth cavity 522, and the cold source is stored between the piston head 54 and the inner top of the cold source storage tube 52; the outer wall of the core tube 53 is provided with an external threaded portion 531, and the external threaded portion 531 is engaged with the internal threaded cavity 523; it also includes a power part 6, which is used to drive the frozen catalyst storage tube 51 to rotate.

[0041] When implementing it, Figure 1 and Figure 3As shown, when the core tube 53 is filled with samples, the core samples have not yet separated from the formation, and there is a large friction between the core tube 53 and the samples. The power member 6 drives the frozen catalyst storage tube 51 to rotate, thereby driving the cold source storage tube 52 to rotate relative to the core tube 53, and the external threaded portion 531 of the core tube 53 is engaged with the internal threaded cavity 523 of the cold source storage tube 52, and then the cold source storage tube 52 moves downward relative to the core tube 53 until the entire core tube 53 is wrapped. At the same time, the piston head 54 moves upward in the smooth cavity 522. A plurality of rubber sealing rings 55 are vertically spaced on the piston head 54. The rubber sealing rings 55 can prevent the cold source from leaking. At the same time, during the upward movement of the piston head 54, the cold source is continuously compressed, causing the pressure of the cold source to increase. When the generated pressure is greater than the threshold of the pressure valve 525, the pressure valve 525 is turned on, and the cold source immediately enters the frozen catalyst storage cavity 511, and after mixing with the frozen catalyst, the core tube 53 and its core sample are frozen.

[0042] More specifically, Figure 1 and Figure 2 As shown, the single-action assembly 4 includes a sleeve 41, a docking head 42 and a ratchet mechanism 43. The upper end of the sleeve 41 is connected to the connecting seat 3, the docking head 42 is rotatably placed in the sleeve 41 through a plurality of bearings, and the lower end of the docking head 42 is connected to the frozen catalyst storage tube 51;

[0043] The ratchet mechanism 43 includes a ratchet ring 431, a drive ring 432 and a pawl 433. The ratchet ring 431 is embedded in the sleeve 41, and a plurality of ratchet teeth 4311 are annularly arranged in the inner cavity of the ratchet ring 431; the drive ring 432 is sleeved on the docking head 42, and a plurality of limit grooves 4321 are annularly arranged in the drive ring 432, and a pawl 433 is rotatably arranged in the limit groove 4321. The pawl 433 extends out of the limit groove 4321 under the action of the torsion spring and engages with the ratchet tooth 4311.

[0044] When implementing it, Figure 1-Figure 3 As shown, when the drill pipe 2 is drilling in the early stage, the drill pipe 2 rotates with the connecting seat 3 through the spring-clamp mechanism, the suspension ring and the suspension ring support, the connecting seat 3 drives the casing 41 to rotate clockwise, and the casing 41 drives the ratchet ring 431 to rotate clockwise. When the ratchet ring 431 rotates clockwise, the direction of the ratchet tooth 4311 is consistent with the direction of the pawl 433, and thus will not drive the driving ring 432 to rotate, nor will it drive the frozen catalyst storage tube 51 to rotate. During the drilling process, the core tube 53 will not generate rotational friction with the core sample, thereby keeping the core sample in its original state to the greatest extent.

[0045] More specifically, Figure 1-Figure 3As shown, the upper end of the sleeve 41 is coaxially connected with a screw rod 7, which is coaxially placed in the connecting seat 3 and meshed with the connecting seat 3. The power member 6 includes a water turbine 61, a drive sleeve 62 and a connecting sleeve 63, the connecting sleeve 63 is coaxially connected to the connecting seat 3, the drive sleeve 62 is coaxially connected to the connecting sleeve 63, the drive sleeve 62 is sleeved on the screw rod 7, and the drive sleeve 62 is connected to the screw rod 7 with a sliding key.

[0046] In specific implementation, the lower end of the core tube 53 is connected with a retaining ring 8 and a retaining spring 9 in sequence; a retaining spring seat 10 is arranged in the drill pipe 2. When the core tube 53 is filled with the sample, the pressure supply of the drilling fluid is increased to drive the water turbine 61 to rotate, and the water turbine 61 drives the driving sleeve 62 to rotate counterclockwise. A sliding key is arranged on the driving sleeve 62 along the axial direction, and a sliding groove is coaxially arranged on the screw 7. The sliding key is slidably placed in the sliding groove, and then drives the screw 7 to rotate through the driving sleeve 62. The screw 7 exits the connecting seat 3 and moves downward. At the same time, the screw 7 drives the sleeve 41 to rotate counterclockwise, and the sleeve 41 drives the ratchet ring 431 to rotate counterclockwise. When the ratchet ring 431 rotates counterclockwise, the driving ring 432 is driven to rotate through a plurality of ratchets 433. The driving ring 43 2, the frozen catalyst storage tube 51 is driven to rotate through the joint 42, and then the cold source storage tube 52 is equivalent to the core tube 53 to rotate, until the core tube 53 completely enters the cold source storage tube 52, the pressure supply of the drilling fluid is stopped, and the cold source also completely enters the frozen catalyst storage box. After freezing the core tube 53 for 10-20 minutes, the salvage device is lowered and the inner tube assembly is lifted up. The retaining spring 9 will clamp the core due to its own gravity and the friction of the core, and the retaining spring seat 10 will break the core when sitting on the step inside the drill bit 1, thereby ensuring the recovery of the core. During this period, the retaining ring 8 can reduce the wear in the process.

[0047] After the core is clamped, the core tube 53 can be kept in place. After the clamping spring 9 is frozen to a layer of ice, the core can be placed in a sealed environment, thereby achieving a pressure-maintaining effect and improving the success rate of core extraction. Finally, the inner tube assembly is lifted up to complete sampling, and the core sample is stored in a liquid nitrogen storage tube or a high-pressure container.

[0048] More specifically, when the core tube 53 is in the initial state before sampling, a portion of the external threaded portion 531 at the upper end of the core tube 53 is engaged with the internal threaded cavity 523, and the exposed length outside the cold source storage tube 52 is smaller than the length between the internal threaded cavity 523 in the cold source storage tube 52 and the external threaded portion 531 of the core tube 53, thereby ensuring that the obtained core can be completely frozen while ensuring that there is enough space to prevent the volatile gas of the cold source from causing excessive pressure in the cold source storage tube 52.

[0049] At the same time, if Figure 1 and Figure 3As shown, a plurality of slurry discharge grooves 524 are arranged in a circular array in the internal thread cavity 523, and the slurry discharge grooves 524 are arranged vertically; a slurry discharge port 532 is arranged through the top of the core tube 53. During the drilling and sampling process, the mud in the core tube 53 is discharged from the slurry discharge port 532, enters between the core tube 53 and the piston head 54, and then discharged from the slurry discharge groove 524.

[0050] A plurality of centralizers 11 are arranged in an annular array inside the drill pipe 2, and the centralizers 11 are in sliding contact with the frozen catalyst storage tube 51. This ensures that the frozen catalyst storage tube 51 is coaxial with the drill pipe 2, and also ensures that the core tube 53 is coaxial with the drill pipe 2, providing a basic guarantee for the relative rotation between the core tube 53 and the cold source storage tube 52.

[0051] As another embodiment, liquid freezing catalyst may be stored in the cold source storage tube 52 . Meanwhile, a cold source may be stored in the freezing catalyst storage cavity 511 . The core tube 53 may be frozen by squeezing the freezing catalyst into the cold source.

[0052] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A natural gas hydrate freezing sampling device, arranged in a drill pipe (2) with a drill bit (1) connected to the bottom, characterized in that: It comprises a connecting seat (3), a single-action component (4) and a freezing sampler (5) which are connected in sequence from top to bottom; The freezing sampler (5) comprises a freezing catalyst storage tube (51), a cold source storage tube (52) and a core tube (53); the upper end of the freezing catalyst storage tube (51) is sealed and connected to the single-action component (4); The cold source storage tube (52) is coaxially arranged in the inner cavity of the frozen catalyst storage tube (51); the lower end of the cold source storage tube (52) is sealed with the frozen catalyst storage tube (51); the upper end of the cold source storage tube (52) is sealed and a gap is left between the cold source storage tube (52) and the inner top of the frozen catalyst storage tube (51); and the upper end of the cold source storage tube (52) is provided with an overflow port (521); An annular frozen catalyst storage cavity (511) for storing frozen catalyst is left between the cold source storage tube (52) and the frozen catalyst storage tube (51), and the overflow port (521) is connected to the inner cavity of the cold source storage tube (52) and the frozen catalyst storage cavity (511) respectively; The inner cavity of the cold source storage tube (52) is respectively provided with a smooth cavity (522) and an internal thread cavity (523) from top to bottom; the upper end of the core tube (53) is connected to a piston head (54) via a connecting rod (541), the piston head (54) is slidably placed in the smooth cavity (522), and a cold source is stored between the piston head (54) and the inner top of the cold source storage tube (52); the outer wall of the core tube (53) is provided with an external thread portion (531), and the external thread portion (531) is meshed with the internal thread cavity (523); It also includes a power member (6), and the power member (6) is used to drive the frozen catalyst storage tube (51) to rotate.

2. A natural gas hydrate freezing sampling device according to claim 1, characterized in that: The single-action assembly (4) comprises a sleeve (41), a docking head (42) and a ratchet mechanism (43); the upper end of the sleeve (41) is connected to the connecting seat (3); the docking head (42) is rotatably placed in the sleeve (41); and the lower end of the docking head (42) is connected to the frozen catalyst storage tube (51); The ratchet mechanism (43) comprises a ratchet ring (431), a drive ring (432) and a ratchet pawl (433); the ratchet ring (431) is embedded in the sleeve (41); and a plurality of ratchet teeth (4311) are annularly arranged in the inner cavity of the ratchet ring (431); The driving ring (432) is sleeved on the docking head (42), and a plurality of limiting grooves (4321) are arranged in a ring array on the driving ring (432). The ratchet (433) is rotatably arranged in the limiting groove (4321), and the ratchet (433) extends out of the limiting groove (4321) under the action of a torsion spring and meshes with the ratchet (4311).

3. A natural gas hydrate freezing sampling device according to claim 2, characterized in that: The upper end of the sleeve (41) is coaxially connected to a screw rod (7), and the screw rod (7) is coaxially disposed in the connecting seat (3) and meshes with the connecting seat (3).

4. A natural gas hydrate freezing sampling device according to claim 3, characterized in that: The power member (6) comprises a water turbine (61), a driving sleeve (62) and a connecting sleeve (63); the connecting sleeve (63) is coaxially rotatably connected to the connecting seat (3); the driving sleeve (62) is coaxially connected to the connecting sleeve (63); the driving sleeve (62) is sleeved on the screw rod (7); and the driving sleeve (62) is key-connected to the screw rod (7).

5. A natural gas hydrate freezing sampling device according to any one of claims 1 to 4, characterized in that: A plurality of pulp discharge grooves (524) are arranged in an annular array inside the internal thread cavity (523), and the pulp discharge grooves (524) are arranged vertically; A slurry discharge port (532) is provided through the top of the core tube (53).

6. A natural gas hydrate freezing sampling device according to claim 5, characterized in that: A filling port (512) is provided through the top of the frozen catalyst storage tube (51), and a sealing plug (513) is provided on the filling port (512).

7. A natural gas hydrate freezing sampling device according to claim 6, characterized in that: The overflow port (521) is provided with a pressure valve (525).

8. A natural gas hydrate freezing sampling device according to claim 7, characterized in that: The lower end of the core tube (53) is connected with a retaining ring (8) and a retaining spring (9) in sequence; A retaining spring seat (10) is arranged inside the drill pipe (2).

9. A natural gas hydrate freezing sampling device according to claim 8, characterized in that: A plurality of centralizers (11) are arranged in an annular array inside the drill pipe (2), and the centralizers (11) are in sliding contact with the frozen catalyst storage tube (51).

10. A natural gas hydrate freezing sampling device according to claim 9, characterized in that: A plurality of rubber sealing rings (55) are vertically spaced apart on the piston head (54).

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