A heat pipe type insulated sampling drill bit and method for drilling natural gas hydrates in polar ice cores and terrestrial permafrost regions.

Abstract

This invention discloses a heat pipe-type insulated sampling drill bit and method for drilling polar ice cores and natural gas hydrates in terrestrial permafrost regions. The drill bit includes a double-walled drill rod, a refrigerant storage chamber, a direct-heating pipe, a spiral heat pipe, and a drill bit. The double-walled drill rod comprises an inner tube and an outer tube with an annular gap between them; the inner wall of the drill rod serves as a core sampler. The refrigerant storage chamber is located at the upper end of the drill rod and is filled with liquid nitrogen; a high-pressure air inlet is located at the upper end of the refrigerant storage chamber. The direct-heating pipe is located at the lower end of the refrigerant storage chamber and is situated within the annular gap of the drill rod. The spiral heat pipe is located at the lower end of the direct-heating pipe and is connected to it; the spiral heat pipe is situated within the annular gap of the drill rod and is filled with Freon. The drill bit is located at the lower end of the drill rod. This invention offers high sample collection efficiency and minimizes disturbance to the original state of ice cores and natural gas hydrates.

Description

Technical Field

[0001] This invention relates to the field of core sampling drilling tools, and particularly to a heat pipe type insulated sampling drilling tool and method. Background Technology

[0002] Air drilling technology is mature and particularly economical and efficient in water-scarce regions such as polar regions, high-altitude permafrost areas, and deserts. Protecting the polar ecosystem is especially crucial in polar drilling, making air drilling particularly important. Obtaining high-fidelity samples is critical in drilling and sampling projects for natural gas hydrates and polar ice cores. Based on the commonalities in the occurrence conditions of natural gas hydrates and ice cores, a thermally insulated sampling drill bit is proposed to solve the aforementioned problems. Summary of the Invention

[0003] In view of the occurrence conditions of natural gas hydrates and ice cores, and in order to effectively save materials, conserve energy, and achieve sustainable utilization, this invention aims to provide a heat pipe insulated sampling drill that is simple to process, pollution-free, has high sample collection efficiency, and causes minimal disturbance to the original state of ice cores and natural gas hydrates.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A heat pipe-type insulated sampling drill bit for drilling natural gas hydrates in polar ice cores and terrestrial permafrost regions includes a double-walled drill pipe, a refrigerant storage chamber, a direct-heat pipe, a spiral heat pipe, and a drill bit, wherein:

[0006] The double-walled drill pipe includes an inner tube and an outer tube, with an annular gap between the inner and outer tubes, and the inner wall of the double-walled drill pipe serves as a core sampler.

[0007] The refrigerant storage chamber is located at the upper end of the double-walled drill rod. The refrigerant storage chamber is filled with liquid nitrogen, and a high-pressure air inlet is provided at the upper end of the refrigerant storage chamber.

[0008] The direct heating pipe is located at the lower end of the refrigerant storage chamber and within the annular gap of the double-walled drill pipe;

[0009] The spiral heat pipe is located at the lower end of the direct heat pipe and is connected to the direct heat pipe. The spiral heat pipe is located in the annular gap of the double-walled drill rod and is filled with Freon.

[0010] The drill bit is located at the lower end of the double-walled drill rod.

[0011] Furthermore, the lower end of the refrigerant storage cavity is a concave cylinder, and a direct heating pipe is embedded in the concave cylinder.

[0012] Furthermore, the outer wall of the refrigerant storage cavity is provided with a heat insulation layer.

[0013] Furthermore, the upper end of the refrigerant storage chamber is provided with a liquid nitrogen injection port and an overflow valve.

[0014] Furthermore, the liquid nitrogen injection port and an overflow valve are symmetrically arranged.

[0015] The direct heat pipe and the spiral heat pipe are integrated into one structure.

[0016] The spiral heat pipe is coaxially embedded in the annular gap at the bottom of the double-walled drill pipe.

[0017] The Freon is one of CH3Cl, CH2F2, or CHF3.

[0018] The top outer wall of the double-walled drill rod is threaded, and the top of the double-walled drill rod is hollow.

[0019] A sampling method for the aforementioned sampling drill bit includes the following steps:

[0020] (1) First, liquid nitrogen is injected into the refrigerant storage chamber, and then room temperature high pressure air is introduced into the high pressure air inlet. The room temperature high pressure air reaches the drill bit through the inner wall of the refrigerant storage chamber, the spiral heat pipe, and the core tube. Under the forced cooling effect of the inner wall of the refrigerant storage chamber and the spiral heat pipe, the temperature of the room temperature high pressure gas reaches the drill bit and decreases, cooling the drill bit and cleaning the bottom of the hole. Then it returns to the ground through the annular gap between the hole wall and the drill bit.

[0021] (2) Since the temperature of the high-pressure gas at room temperature is higher than the temperature of the liquid nitrogen in the refrigerant storage chamber and the temperature of the Freon in the spiral heat pipe, the temperature of the liquid nitrogen will increase. In addition, some of the Freon will sublimate, and the sublimation of the Freon carries the heat from the core tube.

[0022] (3) After sublimation, the Freon carries heat and its density decreases. It reaches the direct heating pipe through the spiral heat pipe and conducts heat with the liquid nitrogen in the refrigerant storage chamber at the top of the direct heating pipe. The Freon condenses into liquid under the action of the ultra-low temperature of the liquid nitrogen and continues to participate in the cooling of the core tube.

[0023] (4) As the heat of Freon is conducted to liquid nitrogen, the temperature of liquid nitrogen will gradually increase and sublimate, and the pressure of the refrigerant storage chamber will increase. When the pressure reaches the set value of the overflow valve, the refrigerant storage chamber will be depressurized.

[0024] Beneficial Effects: Based on the commonalities in the occurrence conditions of natural gas hydrates and ice cores, this invention provides a heat pipe-type insulated sampling drill bit that is simple to operate, pollution-free, has high sample collection efficiency, and minimizes disturbance to the original state of ice cores and natural gas hydrates. Liquid nitrogen has a temperature of -209.8℃ to -196.56℃ at ambient temperature and pressure; while the evaporation temperature of various Freon types is between -23℃ and -70℃. Freon sublimates at the lower end of the spiral heat pipe, carrying away heat from the bottom and turning into a gas, then condenses back into a liquid at the upper part. This invention's heat pipe-type insulated sampling drill bit for drilling polar ice cores and natural gas hydrates in permafrost regions not only provides superior performance during core drilling and uses air as power, resulting in pollution-free operation, but also minimizes disturbance to the original state of ice cores and natural gas hydrates due to their occurrence conditions. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0026] The invention will now be further described with reference to the accompanying drawings.

[0027] like Figure 1 As shown, the present invention provides a heat pipe type insulated sampling drill for drilling natural gas hydrates in polar ice cores and terrestrial permafrost regions, comprising a double-walled drill pipe 11, a refrigerant storage chamber 3, a direct heating pipe 4, a spiral heat pipe 5, and a drill bit 7, wherein:

[0028] The double-walled drill pipe 11 includes an inner tube and an outer tube, with an annular gap between the inner tube and the outer tube. The inner wall of the double-walled drill pipe 11 serves as a core sampler 6. The top outer wall of the double-walled drill pipe 11 is provided with a thread 8 for connection with the male thread at the bottom of a regular drill pipe. The top of the double-walled drill pipe 11 is provided with a cavity 2, which facilitates disassembly, liquid nitrogen injection, and pressure relief.

[0029] The refrigerant storage chamber 3 is located at the upper end of the double-walled drill rod 11. Liquid nitrogen is filled into the refrigerant storage chamber 3, and a high-pressure air inlet 1 is provided at the upper end of the refrigerant storage chamber 3.

[0030] The direct heating pipe 4 is located at the lower end of the refrigerant storage chamber 3 and is situated within the annular gap of the double-walled drill rod 11;

[0031] The spiral heat pipe 5 is located at the lower end of the direct heat pipe 4 and is connected to the direct heat pipe 4. The spiral heat pipe 5 is coaxially embedded in the annular gap at the lower part of the double-walled drill rod 11. Freon is injected into the spiral heat pipe 5.

[0032] The drill bit 7 is located at the lower end of the double-walled drill rod 11.

[0033] Preferably, the lower end of the refrigerant storage cavity 3 is a concave cylinder, and a direct heating pipe 4 is embedded in the concave cylinder.

[0034] Preferably, since liquid nitrogen is injected into the refrigerant chamber, and the temperature of liquid nitrogen at normal pressure is -209.8℃ to -196.56℃, a heat insulation layer is provided on the outer wall of the refrigerant storage chamber 3.

[0035] The upper end of the refrigerant storage chamber 3 is provided with a liquid nitrogen injection port 9 and an overflow valve 10. Preferably, the liquid nitrogen injection port 9 and the overflow valve 10 are symmetrically arranged to prevent vibration.

[0036] Preferably, the direct heat pipe 4 and the spiral heat pipe 5 are integrated into one structure.

[0037] The spiral heat pipe is filled with Freon, and under normal conditions, the evaporation temperature of various Freons is between -23℃ and -70℃. The Freon is preferably one of CH3Cl, CH2F2, or CHF3. After each drilling cycle, the liquid nitrogen content in the sampler's refrigerant chamber is checked, and added as needed.

[0038] The liquid nitrogen in the refrigerant storage chamber 3 is a consumable material and cannot be recycled. When the liquid nitrogen is heated and evaporates, the pressure inside the refrigerant chamber increases. When the pressure reaches the working pressure of the overflow valve, it is automatically depressurized. The Freon in the heat pipe can be recycled.

[0039] In operation, liquid nitrogen is first injected into the refrigerant storage chamber 3. Then, room temperature high-pressure air is introduced into the high-pressure air inlet 1 at the top. The room temperature high-pressure air passes through the inner wall of the refrigerant storage chamber 3, the spiral heat pipe 5, and the core sampler 6 to reach the drill bit 7. Under the forced cooling effect of the inner wall of the refrigerant storage chamber 3 and the spiral heat pipe 5, the room temperature high-pressure gas reaches the drill bit 7 at a lower temperature, which can cool the drill bit 7 and clean the bottom of the hole. Then, it returns to the ground through the annular gap between the hole wall and the drill bit. Because the temperature of the room temperature high-pressure gas is higher than the temperature of the liquid nitrogen in the refrigerant storage chamber 3 and the temperature of the Freon in the spiral heat pipe 5, the temperature of the liquid nitrogen will increase slightly. In addition, the Freon will also rise slightly. The sublimation of Freon carries heat from the core sampler 6, which helps to lower the temperature of the core sampler and protects the original state of the ice core and natural gas hydrate samples obtained from drilling. After sublimation, the Freon carries heat and its density decreases. It then reaches the direct heating pipe 4 via the spiral heat pipe 5. At the top of the direct heating pipe 4, it conducts heat with the liquid nitrogen in the refrigerant storage chamber 3. The Freon condenses into a liquid under the ultra-low temperature of the liquid nitrogen and continues to participate in the cooling of the core sampler 6. As the heat of the Freon is conducted to the liquid nitrogen, the temperature of the liquid nitrogen will gradually increase and sublimate. The pressure in the refrigerant storage chamber 3 will increase. When the pressure reaches the set value of the overflow valve 10, the refrigerant storage chamber 3 will release pressure.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A heat pipe thermal insulation coring drill for polar ice core and terrestrial permafrost zone natural gas hydrate drilling, characterized in that: The double-wall drill pipe (11), the refrigerant storage cavity (3), the straight heat pipe (4), the spiral heat pipe (5), and the drill bit (7) are included. The double-wall drill pipe (11) includes an inner tube and an outer tube, and an annular gap is formed between the inner tube and the outer tube. The refrigerant storage cavity (3) is arranged at the upper end of the double-wall drill pipe (11), and liquid nitrogen is filled in the refrigerant storage cavity (3). The straight heat pipe (4) is arranged at the lower end of the refrigerant storage cavity (3) and located in the annular gap of the double-wall drill pipe (11). The spiral heat pipe (5) is arranged at the lower end of the straight heat pipe (4) and communicates with the straight heat pipe (4), and the spiral heat pipe (5) is located in the annular gap of the double-wall drill pipe (11). The drill bit (7) is arranged at the lower end of the double-wall drill pipe (11). The lower end of the refrigerant storage cavity (3) is a concave cylinder, and the straight heat pipe (4) is embedded in the concave cylinder.

2. The heat pipe thermal insulation coring drill for polar ice core and terrestrial permafrost zone natural gas hydrate drilling according to claim 1, characterized in that: An insulating layer is arranged on the outer wall of the refrigerant storage cavity (3).

3. A heat pipe thermal insulation coring drill for polar ice core and terrestrial permafrost zone natural gas hydrate drilling according to claim 1 or 2, characterized in that: A liquid nitrogen injection port (9) and an overflow valve (10) are arranged at the upper end of the refrigerant storage cavity (3).

4. The heat pipe thermal insulation coring drill for polar ice core and terrestrial permafrost zone natural gas hydrate drilling according to claim 3, characterized in that: The liquid nitrogen injection port (9) and the overflow valve (10) are symmetrically arranged.

5. The heat pipe thermal insulation coring drill for polar ice core and terrestrial permafrost zone natural gas hydrate drilling according to claim 1, characterized in that: The straight heat pipe (4) and the spiral heat pipe (5) are integrated.

6. The heat pipe thermal insulation coring drill for polar ice core and terrestrial permafrost zone natural gas hydrate drilling of claim 1, wherein: The spiral heat pipe (5) is coaxially embedded in the annular gap at the lower end of the double-wall drill pipe (11).

7. The heat pipe thermal insulation coring drill for polar ice core and terrestrial permafrost zone natural gas hydrate drilling of claim 1, wherein: The fluorine refrigerant is one of CH3Cl, CH2F2 and CHF3.

8. The heat pipe thermal insulation coring drill for polar ice core and terrestrial permafrost zone natural gas hydrate drilling of claim 1, wherein: A screw thread (8) is arranged on the outer wall of the top of the double-wall drill pipe (11), and a cavity (2) is arranged in the inner wall of the top of the double-wall drill pipe (11).

9. A method of sampling based on the sampling drill of claim 1, characterized by: The method comprises the following steps: (1) Liquid nitrogen is first injected into the refrigerant storage cavity (3), and then normal-temperature high-pressure air is injected into the high-pressure air input port (1), and the normal-temperature high-pressure air reaches the drill bit (7) through the inner wall of the refrigerant storage cavity (3), the spiral heat pipe (5) and the coring barrel (6), and the temperature of the normal-temperature high-pressure air is reduced under the forced refrigeration of the inner wall of the refrigerant storage cavity (3) and the spiral heat pipe (5), so that the drill bit (7) is cooled and the hole bottom is cleaned, and then the normal-temperature high-pressure air returns to the ground through the annular gap between the hole wall and the drilling tool; (2) Because the temperature of the normal-temperature high-pressure air is higher than the temperature of the liquid nitrogen in the refrigerant storage cavity (3) and the temperature of the fluorine refrigerant in the spiral heat pipe (5), the temperature of the liquid nitrogen increases, and part of the fluorine refrigerant sublimates, and the sublimation of the fluorine refrigerant carries the heat in the coring barrel (6); (3) The fluorine refrigerant after sublimation carries heat and has a reduced density, and reaches the straight heat pipe (4) through the spiral heat pipe (5), and the fluorine refrigerant is condensed into liquid under the action of the liquid nitrogen at an ultra-low temperature, and continues to participate in the cooling of the coring barrel (6); (4) Because the heat of the fluorine refrigerant is transferred to the liquid nitrogen, the temperature of the liquid nitrogen gradually increases and sublimates, the pressure of the refrigerant storage cavity (3) increases, and when the pressure reaches the set value of the overflow valve (10), the refrigerant storage cavity (3) is depressurized.

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