Natural gas hydrate corer soaking device based on gravity assisted heat pipe network

Abstract

The invention discloses a natural gas hydrate corer soaking device based on a gravity assisted heat pipe network, and relates to the technical field of natural gas hydrate in-situ sampling, and the natural gas hydrate corer soaking device comprises a rock core inner pipe used for storing rock cores in the natural gas hydrate sampling process; the soaking pipe is arranged on the outer surface of the rock core inner pipe in a sleeving mode and used for uniformizing temperature distribution of the rock core inner pipe in the axial direction. The pressure-resistant pipe sleeves the outer surface of the soaking pipe and is used for bearing in-situ hydrostatic pressure; and the thermal insulation layer is coated on the outer surface of the compression-resistant pipe. Heat exchange between the coring device and the external environment is reduced through the heat preservation layer, axial temperature homogenization of the rock core inner pipe is achieved through the soaking pipe, the temperatures of all positions of the rock core in the rock core inner pipe tend to be consistent, natural gas hydrate is prevented from being locally heated, subjected to phase change decomposition and migrated to other positions, and the coring effect is improved. Original information such as rock core in-situ saturation, porosity, permeability, rock core structural strength and the like is effectively maintained, and the rock core in-situ microstructure and components are protected.

Description

Technical Field

[0001] The invention relates to the technical field of natural gas hydrate in-situ sampling, in particular to a natural gas hydrate corer heat equalizing device based on a gravity heat pipe network. Background Art

[0002] Natural gas hydrates, also known as combustible ice, are the most promising clean energy for the future.

[0003] Obtaining in-situ authentic core samples of natural gas hydrates is an important prerequisite for resource evaluation, reservoir analysis, improving mining efficiency, studying reservoir deformation, and ensuring operational safety. Since natural gas hydrates exist in low-temperature, high-pressure environments, they are prone to phase changes when the in-situ environmental conditions change. Therefore, the corer is required to have heat preservation and pressure maintenance functions. However, there are still gaps in the existing in-situ active heat preservation technology for natural gas hydrates. Samples obtained by conventional coring equipment and technology often undergo irreversible phase change and decomposition due to changes in temperature and pressure, resulting in the loss of a large amount of in-situ information (such as permeability, porosity, and density, bulk density, etc.), which greatly reduces the scientific research value. Especially when the axial span of the core is large (the size of the natural gas hydrate insulation and pressure coring currently used internationally is in the range of 50-100mm in diameter and 1000-3000mm in length) and the recovery time is long (30 minutes to 1 hour), even if passive insulation technology is used, the local in-situ temperature of the core will often change (such as overcooling, making the core lower than the in-situ temperature), resulting in uneven axial temperature distribution of the core tube of the coring device, causing part of the core to undergo phase change decomposition and migrate to other positions, losing the in-situ saturation distribution and in-situ physical information such as porosity, permeability and core structural strength.

[0004] In view of this, how to provide a natural gas hydrate corer with in-situ heat preservation, pressure maintenance and uniform temperature distribution is a problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a natural gas hydrate corer heat equalization device based on a gravity heat pipe network to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides a heat equalization device for a natural gas hydrate corer based on a gravity heat pipe network, comprising:

[0007] Core inner tube, used for loading core;

[0008] The heat equalizing tube is sleeved on the outer surface of the core inner tube to equalize the temperature of the core inner tube along the length direction;

[0009] The pressure-resistant tube is sleeved on the outer surface of the heat-absorbing tube and is used to bear the in-situ hydrostatic pressure;

[0010] The thermal insulation layer is coated on the outer surface of the pressure-resistant pipe.

[0011] Furthermore, the heat averaging pipe is made of a heat-conducting material, and includes a pipe body and a mesh heat pipe arranged on the inner wall of the pipe body.

[0012] Furthermore, the heat equalizing tube is made by sintering a copper tube body and a phase change material.

[0013] Furthermore, the inner wall of the tube is coated with a thermal conductive silicone grease layer.

[0014] Furthermore, the ends of the core inner tube, the heat-saturating tube and the pressure-resistant tube are flush and welded as one.

[0015] Furthermore, threaded joints and sealing rings are provided at both ends of the pressure-resistant tube.

[0016] The present invention discloses the following technical effects:

[0017] The insulation layer reduces the heat exchange between the core drill and the external environment, and the heat equalization tube achieves the axial heat equalization effect of the core inner tube, so that the temperature of the core in the core inner tube tends to be uniform, preventing the natural gas hydrate core from undergoing phase change and decomposition at some locations and migrating to other locations, effectively preserving the in-situ saturation distribution and in-situ physical information such as porosity, permeability and core structural strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only 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.

[0019] Figure 1 It is a schematic diagram of the structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of the present invention;

[0021] Figure 3 This is a schematic diagram of the heat pipe flat structure;

[0022] Among them, 1. Core inner tube; 2. Heat equalizing tube; 21. Tube body; 22. Mesh heat pipe; 3. Pressure-resistant tube; 4. Insulation layer. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts are within the scope of protection of the present invention.

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] An embodiment of the present invention provides a heat equalizing device for a natural gas hydrate corer based on a gravity heat pipe network, wherein a core inner tube 1 is used to load the core; a heat equalizing tube 2 is sleeved on the outer surface of the core inner tube 1 to equalize the temperature of the core inner tube 1 along the length direction; a pressure-resistant tube 3 is sleeved on the outer surface of the heat equalizing tube 2 to bear the in-situ hydrostatic pressure; and a thermal insulation layer 4 is coated on the outer surface of the pressure-resistant tube 3, and the thermal insulation layer 4 is made of a low thermal conductivity material.

[0026] In this embodiment, heat spreader 2 is made of a copper tube sintered with a phase-change material. It includes a copper body 21 and a mesh heat pipe 22 (filled with phase-change material) located on the inner wall of body 21. The inner wall of body 21 is coated with a layer of thermally conductive silicone grease to further enhance the heat spreader 2's heat distribution. The pressure-resistant tube 3 is equipped with threaded joints and sealing rings at both ends for connecting to other pipe sections.

[0027] During assembly, first apply a layer of thermal grease on the inner wall of the heat-absorbing tube 2, then assemble the core inner tube 1, the heat-absorbing tube 2 and the pressure-resistant tube 3 in sequence, weld the ends of the three together using edge welding, and finally coat the outer surface of the pressure-resistant tube 3 with a low thermal conductivity material to form an insulation layer 4.

[0028] During operation, the core is located in the core inner tube 1. When the corer is retrieved, the temperature of the external environment gradually rises, and the temperature difference along the axial direction of the corer is large (up to 10°C), resulting in uneven core temperature at different locations. The insulation layer 4 can reduce the heat exchange inside and outside the corer. The heat equalization tube 2 can make the axial temperature of the core uniform after the active insulation technology is adopted, ensuring that the temperature at all locations of the core inner tube 1 tends to be consistent, preventing the hydrolysis of natural gas hydrates and water vapor transfer, and protecting the in-situ microstructure and composition of the core.

[0029] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, 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 a limitation on the present invention.

[0030] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A heat soaking device for a natural gas hydrate corer based on a gravity heat pipe network, characterized in that: include: A core inner tube (1) for loading the core; A heat equalizing tube (2) is sleeved on the outer surface of the core inner tube (1) and is used to equalize the temperature of the core inner tube (1) along the length direction; A pressure-resistant tube (3) is sleeved on the outer surface of the heat-equalizing tube (2) and is used to bear the in-situ hydrostatic pressure; The heat-insulating layer (4) is coated on the outer surface of the pressure-resistant pipe (3).

2. The heat soaking device for natural gas hydrate corers based on a gravity heat pipe network according to claim 1, characterized in that: The heat averaging pipe (2) is made of a heat-conducting material and comprises a pipe body (21) and a mesh heat pipe (22) arranged on the inner wall of the pipe body (21).

3. The heat soaking device for natural gas hydrate corers based on a gravity heat pipe network according to claim 2, characterized in that: The heat equalizing tube (2) is made by sintering a copper tube body and a phase change material.

4. The heat soaking device for a natural gas hydrate corer based on a gravity heat pipe network according to claim 2, characterized in that: The inner wall of the tube body (21) is coated with a thermal conductive silicone grease layer.

5. The heat equalization device for a natural gas hydrate corer based on a gravity heat pipe network according to claim 1, characterized in that: The ends of the core inner tube (1), the heat-sparging tube (2) and the pressure-resistant tube (3) are flush and integrally welded.

6. The heat equalization device for a natural gas hydrate corer based on a gravity heat pipe network according to claim 1, characterized in that: Both ends of the pressure-resistant tube (3) are provided with threaded joints and sealing rings.

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