CN109113612B - Hammer type freezing and pressure maintaining double-acting rope sampling drilling tool and method for natural gas hydrate - Google Patents
Hammer type freezing and pressure maintaining double-acting rope sampling drilling tool and method for natural gas hydrate Download PDFInfo
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- CN109113612B CN109113612B CN201811016787.5A CN201811016787A CN109113612B CN 109113612 B CN109113612 B CN 109113612B CN 201811016787 A CN201811016787 A CN 201811016787A CN 109113612 B CN109113612 B CN 109113612B
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B25/00—Apparatus for obtaining or removing undisturbed cores, e.g. core barrels, core extractors
- E21B25/08—Coating, freezing, consolidating cores; Recovering uncontaminated cores or cores at formation pressure
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B25/00—Apparatus for obtaining or removing undisturbed cores, e.g. core barrels, core extractors
- E21B25/10—Formed core retaining or severing means
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B25/00—Apparatus for obtaining or removing undisturbed cores, e.g. core barrels, core extractors
- E21B25/18—Apparatus for obtaining or removing undisturbed cores, e.g. core barrels, core extractors the core receiver being specially adapted for operation under water
Abstract
The invention discloses a hammering type freezing pressure maintaining double-acting rope sampling drilling tool and a method for natural gas hydrate, wherein the sampling drilling tool comprises a fisher, a drilling tool outer pipe, a drilling tool inner pipe assembly and a drill bit, the drilling tool inner pipe assembly comprises a hammering type vibration sampling mechanism, a phase change refrigeration mechanism, a pressure retaining mechanism and a drilling coring mechanism, and the hammering type vibration sampling technology is adopted to ensure the integrity of a natural gas hydrate core; the stability of the natural gas hydrate core is ensured by adopting a heat preservation and pressure maintaining sampling technology; the method is characterized in that a freezing sampling technology is used for assisting a heat preservation and pressure maintaining sampling technology, when pressure maintaining fails, a natural gas hydrate rock core is frozen to-40 ℃ through the phase change heat absorption effect of low-temperature phase change liquid, and the natural gas hydrate is guaranteed not to be decomposed; by combining the technology, the hammering type freezing and pressure maintaining double-acting rope sampling drilling tool and method for the natural gas hydrate can improve the coring success rate of the non-lithologic sediment natural gas hydrate.
Description
Technical Field
The invention relates to a hammer type freezing and pressure maintaining double-acting rope sampling drilling tool and method for natural gas hydrate, and is particularly suitable for the field of drilling and coring of natural gas hydrate in non-lithologic sediments.
Background
The conventional oil and gas resources in China are far from meeting the requirements of economic and social development. The natural gas hydrate mainly exists at the edge of world ocean continents and in frozen soil zones with high latitude, has the characteristics of high energy density, wide distribution, large scale, shallow burial and the like, and the produced natural gas can meet the requirements of energy, economy and environment, and is novel clean energy with commercial development prospect. The natural gas hydrate can only exist under certain temperature and pressure conditions, generally, the temperature is required to be lower than 0-10 ℃, the pressure is required to be higher than 10MPa, once the temperature is increased or the pressure is reduced, methane gas can escape, and the solid natural gas hydrate can be decomposed, so that how to obtain a high-fidelity natural gas hydrate sample is a great problem in natural gas hydrate exploration and development. Research work in the fidelity drilling sampling of natural gas hydrates is actively conducted in all countries of the world. At present, natural gas hydrate fidelity samplers at home and abroad mainly comprise two design ideas: one is a hole bottom heat preservation and pressure maintaining sampler, and the other is a hole bottom freezing sampler.
The heat preservation and pressure maintaining sampling method is characterized in that a specially designed pressure maintaining core tube is sealed and sealed by utilizing a ball valve, a flap valve and the like after a core is broken and in the lifting process, and passive heat preservation is realized by adopting a heat preservation material, namely, the in-situ pressure and temperature of a natural gas hydrate reservoir are maintained in a mechanical pressure maintaining mode to obtain the natural gas hydrate core with high fidelity. The sampler adopts a mechanical pure active pressure maintaining mode to obtain the rock core, and the method has technical defects. Once the tightness of the mechanical hold-down mechanism is slightly reduced, the core cannot maintain the initial pressure, resulting in a failed core extraction. And when the design pressure of the sampler reaches a certain level, if the pressure maintaining capacity is required to be increased, the material and sealing performance of the sampler need to be greatly improved, and the improvement is not easy to realize. The heat preservation method of the core in the hole mainly adopts a heat preservation material to realize a passive heat preservation method, and the passive heat preservation method cannot maintain the original temperature of the natural gas hydrate core under the complex thermal condition of drilling sampling. Only foreign individual samplers adopt a thermoelectric inner tube heat preservation mode, but the heat preservation effect is not ideal, and the success rate of drilling the natural gas hydrate fidelity core is low.
The natural gas hydrate sample freezing and sampling method is a method for freezing a natural gas hydrate sample at the bottom of a hole by utilizing a cold source, reducing the critical decomposition pressure of the natural gas hydrate through low temperature, simultaneously exciting a self-protection effect, inhibiting the decomposition of the natural gas hydrate and obtaining the natural gas hydrate sample. The hole bottom freezing sampling method adopts phase-changeable fluid as a cold source, stores the cold source in a cold storage cavity of a hole bottom drilling tool, triggers a control mechanism of the drilling tool after drilling is finished, injects the cold source into the freezing cavity, and freezes the natural gas hydrate in a sample tube to a required low-temperature interval through the cold source gasification heat absorption. However, the method can change the original basic physical properties of the natural gas hydrate core, and the test data such as sound waves, resistivity and the like of the core are changed.
Disclosure of Invention
The invention aims to provide a hammer type freezing and pressure maintaining double-acting rope sampling drilling tool for natural gas hydrate and a method for sampling by adopting the drilling tool, aiming at the defects of the prior art, the hammer type freezing and pressure maintaining double-acting rope sampling drilling tool for the natural gas hydrate is a hammer type coring tool driven by hydraulic pressure, pressure maintaining sampling technology and freezing sampling technology are integrated in one set of drilling tool, and high-fidelity coring of the natural gas hydrate is realized through double effects of freezing and pressure maintaining.
In order to achieve the purpose, the invention adopts the following technical scheme:
a natural gas hydrate hammering type freezing pressure maintaining double-acting rope sampling drilling tool comprises a fisher, a drilling tool outer pipe, a drilling tool inner pipe assembly and a drill bit, wherein the drilling tool inner pipe assembly is arranged inside the drilling tool outer pipe, an annular gap is arranged between the drilling tool outer pipe and the drilling tool inner pipe assembly, the drill bit is arranged at a drilling working end of the drilling tool outer pipe, and the natural gas hydrate hammering type freezing pressure maintaining double-acting rope sampling drilling tool is characterized in that the drilling tool inner pipe assembly comprises a hammering type vibration sampling mechanism, a phase change refrigerating mechanism, a,
the hammering type vibration sampling mechanism comprises a control rod, a movable valve, a sealing ring, a piston, a valve body, a valve spring and an anvil, wherein a groove connected with a fisher is formed in the top of the control rod, and a boss on the upper portion of the control rod is located in a concave table on the upper portion of an outer pipe of the drilling tool; the movable valve, the sealing ring, the piston, the valve body, the valve spring and the anvil are all sleeved outside the control rod and are coaxially arranged with the control rod; the movable valve is arranged above the valve body, and the lower part of the movable valve is contacted with the piston; the piston is positioned in the valve body, and the diameter of the middle part of the piston is larger than the aperture of the upper part of the valve body; the valve spring is arranged in the valve body, the upper part of the valve spring is contacted with the piston, and the lower part of the valve spring is contacted with the anvil; the anvil is provided with a concave ring groove for fixing the valve body, the concave ring groove divides the anvil into two parts, the part positioned above the concave ring groove is arranged in the valve body, the part positioned below the concave ring groove is arranged outside the valve body, the bottom of the anvil is connected with a cavity pipe, the bottom of the cavity pipe is of an open structure, the cavity pipe is divided into two cavities which are respectively a cold source cavity and a pressure chamber, and the cold source cavity is positioned above the pressure chamber;
the phase-change refrigeration mechanism comprises an exhaust valve, a cold source cavity and a control valve, wherein a cold source cavity heat-insulating layer covers the inner wall of the cold source cavity; the exhaust valve is arranged at a cold source inlet of the cavity pipe and comprises an exhaust valve body, an exhaust valve spring and an exhaust valve core, and the exhaust valve body is connected with the cavity pipe through threads; the exhaust valve spring and the exhaust valve core are arranged in the exhaust valve body, one end of the exhaust valve spring is connected with the exhaust valve body, the other end of the exhaust valve spring is connected with the exhaust valve core, and the pretightening force of the exhaust valve spring is used for propping the exhaust valve core on a through hole of the exhaust valve body; the control valve comprises a control valve core, a control valve spring, a control valve top block and a top block chamber, wherein the control valve spring is used for pressing the control valve core at an outlet of the cold source cavity; the control valve top block is arranged in a slideway of the control rod, part of the control valve top block protrudes out of the control rod and abuts against the lower part of the control valve core to lock the control valve core, and when the control rod moves upwards, the control valve top block presses the control valve top block into a top block chamber at the bottom of the slideway of the control rod through the control valve core;
the pressure maintaining mechanism comprises a pressure chamber, a flap valve and a torsion spring, wherein a pressure chamber heat-insulating layer covers the inner wall of the pressure chamber, the fixed end of the flap valve is hinged with the lower part of the side wall of the cavity pipe, the torsion spring is arranged at the hinged part, the free end of the flap valve is contacted with the control rod, and the upper flap valve heat-insulating layer is arranged on one side of the flap valve facing the pressure chamber; the torsion spring is arranged at the hinged position of the flap valve and the cavity pipe and is used for driving the flap valve to turn;
the drilling coring mechanism comprises a coring barrel, a coring barrel piston, cutting teeth, a core tube and a cable spring, wherein the core tube and the cavity tube are coaxially arranged, the upper part of the core tube is connected with the cavity tube, and the bottom of the core tube is connected with the cutting teeth; the core barrel is positioned in the core tube and is seated on the step in the core tube, and a core barrel piston connected with the bottom of the control rod is arranged in the core barrel; the cable spring is fixed at the lower part of the coring barrel, so that the natural gas hydrate core cannot fall out of the coring barrel during coring.
A hammer type freezing and pressure maintaining double-acting rope sampling method for natural gas hydrate is characterized in that the sampling method adopts the hammer type freezing and pressure maintaining double-acting rope sampling drilling tool for sampling, and specifically comprises the following steps:
① ground surface preparation stage, before drilling and coring natural gas hydrate, firstly, pre-tightening force of a control valve is set according to pressure in a cold source cavity and self-weight of the control valve, a control valve core, a control valve spring and a control valve top block are installed, so that when the back pressure at the lower part of the control valve core is less than 1MPa, the control valve is automatically opened to enable the cold source to flow out from the cold source cavity;
② preparing in the hole, namely after the cold source is filled, putting the drilling tool inner tube assembly into the drilling tool outer tube, enabling the drilling tool inner tube assembly to reach the hole bottom working position, enabling the boss on the upper part of the control rod to be seated in the concave table on the upper part of the drilling tool outer tube, integrally suspending the drilling tool inner tube assembly in the drilling tool outer tube, and keeping the distance between the lower part of the cutting tooth and the stratum drilled by the natural gas hydrate to be 2-4 mm;
③ drilling and coring, wherein the drilling tool inner tube assembly is driven to move downwards by pumping circulating drilling fluid, which enters into a closed space formed by the outer tube of the drilling tool, the valve body and the sealing ring from the drilling fluid inlet on the upper part of the control rod, the movable valve is driven to move downwards, the movable valve drives the piston compression valve spring to move downwards to hammer the anvil on the lower part, and impact force is generated to drive the drilling tool to impact downwards to drive the cutting teeth to impact into the natural gas hydrate stratum;
④ pressure maintaining core stage, namely, after coring, throwing a fisher which is clamped in a groove at the top of a control rod, lifting a drilling tool, driving a coring barrel to ascend by the control rod, and descending the drilling tool integrally relative to the control rod under the action of self weight;
⑤ core freezing stage, wherein in the drilling tool lifting process, the control valve top block moves downwards relative to the control rod, when the control valve top block moves to the state that the lower surface of the control valve top block is flush with the upper surface of the top block chamber, the control valve top block retreats into the top block chamber under the action of downward pressure exerted by the control valve core, at the moment, the control valve core seals the outlet at the lower part of the cold source chamber under the action of the pretightening force of the control valve spring and the pressure in the pressure chamber, when the pressure in the pressure chamber is lower than 1MPa, the control valve core compresses the control valve spring under the action of the internal pressure of the cold source chamber, the cold source chamber is opened, the cold source is injected into the annular gap between the pressure chamber and the core barrel, and the core of the natural gas hydrate in the core barrel is frozen;
⑥ and a continuous drilling stage, namely, lifting the inner pipe assembly of the drilling tool to the hole opening to obtain a natural gas hydrate core, then starting the pump, rotating the outer pipe of the drilling tool to drive the drill bit to continuously drill downwards to the stratum with the obtained natural gas hydrate core, and then repeating the steps to continuously drill for coring.
Wherein the cold source is low-temperature phase-change liquid, and the low-temperature phase-change liquid adopts an alcohol-dry ice mixture with the temperature of 0 ℃ to-120 ℃, an acetone-dry ice mixture with the temperature of 0 ℃ to-130 ℃ or liquid nitrogen with the temperature of-197 ℃.
Through the design scheme, the invention can bring the following beneficial effects: the invention applies the natural gas hydrate heat preservation and pressure maintaining sampling technology, the freezing sampling technology and the hammering type vibration sampling technology to the natural gas hydrate drilling coring in the non-lithologic sediment; the integrity of the natural gas hydrate core is ensured by adopting a hammering type vibration sampling technology; the stability of the natural gas hydrate core is ensured by adopting a heat preservation and pressure maintaining sampling technology; the method is characterized in that a freezing sampling technology is used for assisting a heat preservation and pressure maintaining sampling technology, and when pressure maintaining fails, a natural gas hydrate rock core is frozen to-40 ℃ through the phase change heat absorption effect of low-temperature phase change liquid, so that the natural gas hydrate is not decomposed; by combining the technology, the hammering type freezing and pressure maintaining double-acting rope sampling drilling tool and method for the natural gas hydrate can improve the coring success rate of the non-lithologic sediment natural gas hydrate.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention to the right, and in which:
fig. 1 is a schematic structural diagram of a hammer-hammer type freeze-pressure-maintaining double-acting rope sampling drilling tool for natural gas hydrates in an embodiment of the invention.
Fig. 2 is a partially enlarged view of fig. 1.
Fig. 3 is a second enlarged view of a portion of fig. 1.
The respective symbols in the figure are as follows: 1-control rod, 2-drilling tool outer tube, 3-movable valve, 4-sealing ring, 5-piston, 6-valve body, 7-valve spring, 8-anvil, 9-exhaust valve body, 10-cavity tube, 11-exhaust valve spring, 12-exhaust valve core, 13-cold source cavity heat preservation layer, 14-control valve core, 15-control valve spring, 16-control valve top block, 17-top block chamber, 18-pressure chamber heat preservation layer, 19-upper heat preservation layer of flap valve, 20-flap valve, 21-torsion spring, 22-coring barrel, 23-coring barrel piston, 24-cutting tooth, 25-core tube, 26-seizing spring and 27-drill bit.
Detailed Description
In order to more clearly illustrate the invention, the invention is further described below with reference to preferred embodiments and the accompanying drawings. As will be appreciated by those skilled in the art. The following detailed description is illustrative rather than limiting in nature and is not intended to limit the scope of the invention. Well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.
The invention combines hammering type vibration sampling, pressure maintaining sampling and freezing sampling to achieve the purpose of improving the heart rate of the natural gas hydrate core in the non-lithologic sediment.
The invention adopts low-temperature phase-change liquid as a cold source, and the low-temperature phase-change liquid adopts low-temperature fluid which can be gasified and absorb heat, such as alcohol-dry ice mixture with the temperature of 0 ℃ to-120 ℃, acetone-dry ice mixture with the temperature of 0 ℃ to-130 ℃ or liquid nitrogen with the temperature of-197 ℃ and the like;
as shown in fig. 1, 2 and 3, the natural gas hydrate hammering type freezing pressure maintaining double-acting rope sampling drilling tool comprises a fisher, an outer drilling tool pipe 2, an inner drilling tool pipe assembly and a drill bit 27, wherein the inner drilling tool pipe assembly is arranged inside the outer drilling tool pipe 2, an annular gap is arranged between the inner drilling tool pipe assembly and the outer drilling tool pipe 2, the drill bit 27 is arranged at a drilling working end of the outer drilling tool pipe 2, and the natural gas hydrate hammering type freezing pressure maintaining double-acting rope sampling drilling tool is characterized in that the inner drilling tool pipe assembly comprises a hammering type vibration sampling mechanism, a phase change refrigerating mechanism,
the hammering type vibration sampling mechanism comprises a control rod 1, a movable valve 3, a sealing ring 4, a piston 5, a valve body 6, a valve spring 7 and an anvil 8, wherein a groove connected with a fisher is formed in the top of the control rod 1, and a boss on the upper portion of the control rod 1 is located in a concave table on the upper portion of an outer pipe 2 of the drilling tool; the movable valve 3, the sealing ring 4, the piston 5, the valve body 6, the valve spring 7 and the anvil 8 are all sleeved outside the control rod 1 and are coaxially arranged with the control rod 1; the movable valve 3 is arranged above the valve body 6, and the lower part of the movable valve 3 is contacted with the piston 5; the piston 5 is positioned in the valve body 6, and the diameter of the middle part of the piston 5 is larger than the hole diameter of the upper part of the valve body 6, so that the middle part of the piston 5 is propped against the top in the valve body 6 under the action of the valve spring 7; the valve spring 7 is arranged in the valve body 6, the upper part of the valve spring 7 is contacted with the piston 5, and the lower part of the valve spring 7 is contacted with the anvil 8, so that a certain distance is kept between the piston 5 and the anvil 8; the anvil 8 is provided with a concave ring groove for fixing the valve body 6, the concave ring groove divides the anvil 8 into two parts, the part positioned above the concave ring groove is arranged in the valve body 6, the part positioned below the concave ring groove is arranged outside the valve body 6, the bottom of the anvil 8 is connected with a cavity pipe 10, wherein the bottom of the cavity pipe 10 is of an open structure, the cavity pipe 10 is divided into two cavities which are respectively a cold source cavity and a pressure chamber, and the cold source cavity is positioned above the pressure chamber;
the phase-change refrigeration mechanism comprises an exhaust valve, a cold source cavity and a control valve, and a cold source cavity heat-insulating layer 13 covers the inner wall of the cold source cavity to ensure heat insulation with the outside; the exhaust valve is arranged at a cold source inlet of the cavity pipe 10 and comprises an exhaust valve body 9, an exhaust valve spring 11 and an exhaust valve core 12, and the exhaust valve body 9 is connected with the cavity pipe 10 through threads; the exhaust valve spring 11 and the exhaust valve core 12 are arranged inside the exhaust valve body 9, one end of the exhaust valve spring 11 is connected with the exhaust valve body 9, the other end of the exhaust valve spring 11 is connected with the exhaust valve core 12, and the pretightening force of the exhaust valve spring 11 is used for propping the exhaust valve core 12 against a through hole of the exhaust valve body 9, so that when the gas pressure in the cold source cavity is overlarge, the pressure in the cold source cavity is regulated through exhaust; the control valve comprises a control valve core 14, a control valve spring 15, a control valve top block 16 and a top block chamber 17, wherein the control valve spring 15 is used for tightly pressing the control valve core 14 on an outlet of the cold source cavity and sealing the outlet of the cold source cavity; the control valve top block 16 is arranged in a slide way of the control rod 1, and a part of the control valve top block 16 protrudes out of the control rod 1 and abuts against the lower part of the control valve core 14, so that the control valve core 14 is locked and cannot be opened in a hole coring stage; when the control rod 1 moves upwards, the control valve top block 16 is pressed into a top block chamber 17 at the bottom of the control rod 1 slide way through the control valve core 14, and at the moment, the control valve top block 16 does not provide an upward jacking force for the control valve core 14 any more;
the pressure maintaining mechanism comprises a pressure chamber, a flap valve 20 and a torsion spring 21, wherein a pressure chamber heat-insulating layer 18 covers the inner wall of the pressure chamber to ensure heat insulation with the outside, the fixed end of the flap valve 20 is hinged with the lower part of the side wall of the cavity pipe 10, the torsion spring 21 is arranged at the hinged part, the free end of the flap valve 20 is in contact with the control rod 1, an upper flap valve heat-insulating layer 19 is arranged on the upper surface of the flap valve 20, and the pressure chamber heat-insulating layer 18 and the upper flap valve heat-insulating layer 19 ensure that a natural gas hydrate rock core cannot generate a large amount of heat exchange with the outside in a pressure maintaining process or a; the torsion spring 21 is arranged at the hinged position of the flap valve 20 and the cavity pipe 10, the flap valve 20 is in a turnover state under the action of the torsion spring 21, but the flap valve 20 is pressed on the control rod 1 under the condition of no work due to the action of the control rod 1; when the control rod 1 moves upwards to drive the coring barrel 22 to enter the pressure chamber, the flap valve 20 seals the lower part of the pressure chamber under the action of the torsion spring 21;
the drilling and coring mechanism comprises a coring barrel 22, a coring barrel piston 23, cutting teeth 24, a core tube 25 and a cable spring 26, wherein the core tube 25 and the cavity tube 10 are coaxially arranged, the upper part of the core tube 25 is connected with the cavity tube 10, the bottom of the core tube 25 is connected with the cutting teeth 24, and the core tube 25 drives the cutting teeth 24 to impact into a natural gas hydrate stratum through impact force transmitted by the hammering type vibration sampling mechanism to obtain a natural gas hydrate core; the core barrel 22 is positioned in the core barrel 25 and is seated on the inner step of the core barrel 25, a core barrel piston 23 connected with the bottom of the control rod 1 is arranged in the core barrel 22, and in the core taking process, the core barrel piston 23 moves upwards relative to the core barrel 22 to generate suction force to assist a core to enter the core barrel 22; the cable spring 26 is fixed at the lower part of the coring barrel 22, so that the natural gas hydrate core cannot fall out of the coring barrel 22 during coring.
A hammering type freezing pressure maintaining double-acting rope coring method for natural gas hydrates comprises the following steps:
① ground surface preparation stage, before drilling and coring natural gas hydrate, firstly, setting pretightening force of a control valve according to pressure in a cold source cavity and self weight of the control valve, installing a control valve core 14, a control valve spring 15 and a control valve top block 16, so that when the backpressure at the lower part of the control valve core 14 is less than 1MPa, the control valve is automatically opened to make cold source flow out from the cold source cavity, then, injecting a cold source into the cold source cavity, detaching an exhaust valve body 9, an exhaust valve spring 11 and an exhaust valve core 12 from a cavity pipe 10, injecting liquid nitrogen into the cold source cavity to precool the cold source cavity, continuously injecting liquid nitrogen, when the temperature in the cold source cavity reaches-100 ℃, indicating that the precooling requirement is met, after precooling, injecting selected low-temperature phase-change liquid into the cold source cavity, wherein the injection amount of the low-temperature phase-change liquid is 80% of the cold source cavity, then injecting nitrogen into the cold source cavity to adjust the pressure therein, and ensuring that when the backpressure at the lower part of the control valve core 14 is less than 1MPa, the cold source is automatically opened to make the cold source flow out;
② preparation stage in the hole, after the cold source is filled, the drilling tool inner tube assembly is put into the drilling tool outer tube 2, the drilling tool inner tube assembly reaches the working position of the hole bottom, the boss on the upper part of the control rod 1 is seated in the concave table on the upper part of the drilling tool outer tube 2, the drilling tool inner tube assembly is integrally suspended in the drilling tool outer tube 2, and the distance between the lower part of the cutting tooth 24 and the ground layer drilled by the natural gas hydrate is kept between 2mm and 4mm, at this time, the control valve top block 16 is used for jacking the control valve core 14 under the action of the control rod 1 and plugging the outlet on the lower part of the cold source cavity, so that the;
③ drilling and coring, wherein after the drilling tool inner tube assembly reaches a working position, a pump is started to circulate drilling fluid, the drilling fluid enters a closed space formed by the drilling tool outer tube 2, the valve body 6 and the sealing ring 4 from a drilling fluid inlet at the upper part of the control rod 1, the movable valve 3 is pushed to move downwards, the movable valve 3 drives the piston 5 to compress the valve spring 7 to move downwards to hammer the anvil 8 at the lower part, impact force is generated to drive the drilling tool to impact downwards to drive the cutting teeth 24 to impact the natural gas hydrate stratum, in the process of moving downwards, the movable valve 3 is blocked by the valve body 6 to stop moving downwards, the piston 5 continues to move downwards under the action of inertia, the movable valve 3 and the piston 5 are separated from each other, the drilling fluid enters the valve body 6 from the middle part of a through hole in the middle of the piston 5, enters a liquid inlet at the upper part of the anvil 8 and then flows out from a liquid outlet at the lower part of the drilling tool inner tube assembly and the drilling tool outer tube 2, after the piston 5 and the anvil 8 are contacted, the piston 5 moves upwards under the action of the hammering the action of the valve spring 7 to hammer the upper end surface of the valve body 6, the drilling fluid falls into a circulation channel of the core, the drilling fluid blocking the drilling tool, the drilling fluid enters the core 22, the natural gas hydrate stratum, the natural gas hydrate;
④ pressure maintaining core stage, namely, after coring, throwing a fisher which is clamped in a groove at the top of a control rod 1, lifting a drilling tool, driving a coring barrel 22 to move upwards by the control rod 1, and moving the drilling tool integrally downwards relative to the control rod 1 under the action of self weight;
⑤ core freezing stage, wherein in the drilling tool lifting process, the control valve top block 16 moves downwards relative to the control rod 1, when the control valve top block moves to the top block chamber 17, the control valve top block 16 retreats into the top block chamber 17 under the action of downward pressure exerted by the control valve core 14, at the moment, the control valve core 14 is sealed at the outlet at the lower part of the cold source cavity under the action of the pretightening force of the control valve spring 15 and the pressure in the pressure chamber, when the sealing performance of the flap valve 20 is reduced to cause the pressure in the pressure chamber to be lower than 1MPa, the control valve core 14 compresses the control valve spring 15 under the action of the pressure in the cold source cavity, opens the cold source cavity, the cold source is injected into the annular gap between the cold source pressure chamber and the core barrel 22, the natural gas hydrate core in the core barrel 22 is frozen to be below-40 ℃ through the phase change heat absorption effect of the low-temperature phase change liquid, the natural gas hydrate is ensured not to be decomposed, and the cold source does not lose the cold energy;
⑥ and a continuous drilling stage, namely, lifting the inner pipe assembly of the drilling tool to the hole opening to obtain a hydrate core, then starting the pump, rotating the outer pipe 2 to drive the drill bit 27 to continuously drill downwards to the stratum with the obtained core, and then repeating the steps to continuously drill for coring.
Claims (3)
1. A natural gas hydrate hammering type freezing pressure maintaining double-acting rope sampling drilling tool comprises a fisher, a drilling tool outer pipe (2), a drilling tool inner pipe assembly and a drill bit (27), wherein the drilling tool inner pipe assembly is arranged inside the drilling tool outer pipe (2), an annular gap is arranged between the drilling tool outer pipe and the drilling tool outer pipe (2), the drill bit (27) is arranged at a drilling working end of the drilling tool outer pipe (2), and the natural gas hydrate hammering type freezing pressure maintaining double-acting rope sampling drilling tool is characterized in that the drilling tool inner pipe assembly comprises a hammering type vibration sampling mechanism, a phase change refrigerating mechanism, a,
the hammering type vibration sampling mechanism comprises a control rod (1), a movable valve (3), a sealing ring (4), a piston (5), a valve body (6), a valve spring (7) and an anvil (8), wherein a groove connected with a fisher is formed in the top of the control rod (1), and a boss on the upper portion of the control rod (1) is located in a concave table on the upper portion of an outer pipe (2) of the drilling tool; the movable valve (3), the sealing ring (4), the piston (5), the valve body (6), the valve spring (7) and the anvil (8) are all sleeved outside the control rod (1) and are coaxially arranged with the control rod (1); the movable valve (3) is arranged above the valve body (6), and the lower part of the movable valve (3) is contacted with the piston (5); the piston (5) is positioned in the valve body (6), and the diameter of the middle part of the piston (5) is larger than the aperture of the upper part of the valve body (6); the valve spring (7) is arranged in the valve body (6), the upper part of the valve spring (7) is contacted with the piston (5), and the lower part of the valve spring (7) is contacted with the anvil (8); the anvil (8) is provided with a concave ring groove for fixing the valve body (6), the anvil (8) is divided into two parts by the concave ring groove, the part positioned above the concave ring groove is arranged in the valve body (6), the part positioned below the concave ring groove is arranged outside the valve body (6), the bottom of the anvil (8) is connected with a cavity pipe (10), the bottom of the cavity pipe (10) is of an open structure, the cavity pipe (10) is divided into two cavities which are respectively a cold source cavity and a pressure chamber, and the cold source cavity is positioned above the pressure chamber;
the phase-change refrigeration mechanism comprises an exhaust valve, a cold source cavity and a control valve, wherein a cold source cavity heat-insulating layer (13) is covered on the inner wall of the cold source cavity; the exhaust valve is arranged at a cold source inlet of the cavity pipe (10), and comprises an exhaust valve body (9), an exhaust valve spring (11) and an exhaust valve core (12), wherein the exhaust valve body (9) is connected with the cavity pipe (10) through threads; the exhaust valve spring (11) and the exhaust valve core (12) are arranged inside the exhaust valve body (9), one end of the exhaust valve spring (11) is connected with the exhaust valve body (9), the other end of the exhaust valve spring (11) is connected with the exhaust valve core (12), and the pretightening force of the exhaust valve spring (11) is used for propping the exhaust valve core (12) against a through hole of the exhaust valve body (9); the control valve comprises a control valve core (14), a control valve spring (15), a control valve top block (16) and a top block chamber (17), wherein the control valve spring (15) is used for pressing the control valve core (14) at an outlet of the cold source cavity; the control valve top block (16) is arranged in a slide way of the control rod (1), part of the control valve top block (16) protrudes out of the control rod (1) and abuts against the lower part of the control valve core (14) to lock the control valve core (14), and when the control rod (1) moves upwards, the control valve top block (16) is pressed into a top block chamber (17) at the bottom of the slide way of the control rod (1) through the control valve core (14);
the pressure maintaining mechanism comprises a pressure chamber, a flap valve (20) and a torsion spring (21), a pressure chamber heat-insulating layer (18) covers the inner wall of the pressure chamber, the fixed end of the flap valve (20) is hinged with the lower part of the side wall of the cavity pipe (10), the torsion spring (21) is arranged at the hinged part, the free end of the flap valve (20) is in contact with the control rod (1), and a flap valve upper heat-insulating layer (19) is arranged on one side of the flap valve (20) facing the pressure chamber; the torsion spring (21) is arranged at the hinged position of the flap valve (20) and the cavity pipe (10), and the torsion spring (21) is used for driving the flap valve (20) to turn over;
the drilling and coring mechanism comprises a coring barrel (22), a coring barrel piston (23), cutting teeth (24), a core tube (25) and cable springs (26), wherein the core tube (25) and the cavity tube (10) are coaxially arranged, the upper part of the core tube (25) is connected with the cavity tube (10), and the bottom of the core tube (25) is connected with the cutting teeth (24); the core barrel (22) is positioned in the core tube (25) and is seated on the inner step of the core tube (25), and a core barrel piston (23) connected with the bottom of the control rod (1) is arranged in the core barrel (22); the cable spring (26) is fixed at the lower part of the coring barrel (22), so that the natural gas hydrate core cannot fall out of the coring barrel (22) during coring;
drilling fluid enters a closed space formed by the outer pipe (2) of the drilling tool, the valve body (6) and the sealing ring (4) from a drilling fluid inlet at the upper part of the control rod (1) and pushes the movable valve (3) to move downwards;
the movable valve (3) stops moving downwards due to the obstruction of the valve body (6) in the process that the piston (5) moves downwards; the piston (5) continues to move downwards under the action of inertia, the movable valve (3) and the piston (5) are separated from each other, drilling fluid enters the valve body (6) from the middle of the through hole in the middle of the piston (5), enters from the liquid inlet in the upper part of the anvil (8), then flows out from the liquid outlet in the lower part of the anvil, and finally flows out from the annular gap between the inner pipe assembly of the drilling tool and the outer pipe (2) of the drilling tool.
2. A natural gas hydrate hammering type freezing and pressure maintaining double-acting rope sampling method is characterized in that the sampling method adopts the natural gas hydrate hammering type freezing and pressure maintaining double-acting rope sampling drilling tool disclosed by claim 1 to perform sampling, and specifically comprises the following steps:
① ground surface preparation stage, before drilling and coring natural gas hydrate, firstly, pre-tightening force of a control valve is set according to pressure in a cold source cavity and self-weight of the control valve, a control valve core (14), a control valve spring (15) and a control valve top block (16) are installed, so that when the back pressure at the lower part of the control valve core (14) is less than 1MPa, the control valve is automatically opened to enable cold source to flow out from the cold source cavity, then an exhaust valve body (9), an exhaust valve spring (11) and an exhaust valve core (12) are detached from a cavity body pipe (10), liquid nitrogen is injected into the cold source cavity to pre-cool the cold source cavity, the pre-cooling is finished when the temperature in the cold source cavity reaches-100 ℃, after the pre-cooling is finished, a cold source is injected into the cold source cavity, the injection amount of the cold source is 80% of the total volume of the cold source cavity, then the pressure in the nitrogen is injected into the cold source cavity, so that;
② preparation stage in the hole, after cold source filling, putting the drilling tool inner pipe assembly into the drilling tool outer pipe (2), the drilling tool inner pipe assembly reaches the hole bottom working position, the boss at the upper part of the control rod (1) is seated in the concave table at the upper part of the drilling tool outer pipe (2), the drilling tool inner pipe assembly is integrally suspended in the drilling tool outer pipe (2), the distance between the lower part of the cutting tooth (24) and the ground layer drilled by the natural gas hydrate is kept between 2mm and 4mm, at the moment, the control valve top block (16) jacks the control valve core (14) under the action of the control rod (1), and the outlet at the lower part of the cold source cavity is blocked, so that the cold source can not flow out from the cold source cavity in;
③ drilling and coring, wherein the drilling tool inner tube assembly reaches a working position, a pump is started to circulate drilling fluid, the drilling fluid enters a closed space formed by the drilling tool outer tube (2), the valve body (6) and the sealing ring (4) from a drilling fluid inlet at the upper part of the control rod (1), the movable valve (3) is pushed to move downwards, the movable valve (3) drives the piston (5) to compress a valve spring (7) to move downwards to hammer an anvil (8) at the lower part, impact force is generated to drive the drilling tool to impact downwards to drive the cutting teeth (24) to impact and enter a natural gas hydrate stratum, the movable valve (3) stops moving downwards due to the obstruction of the valve body (6) in the downward movement process of the piston (5), the piston (5) continues to move downwards under the inertia effect, the movable valve (3) and the piston (5) are separated from each other, the drilling fluid enters the valve body (6) from the middle part of a through hole in the middle of the piston (5), enters a liquid outlet at the upper part of the iron anvil (8) and then flows out from a liquid inlet at the lower part of the core tube (6), the core barrel (5) after the drilling tool inner tube assembly and the core (2), the core (5) and the natural gas hydrate stratum, the natural gas hydrate core barrel is taken out from the core barrel, the natural gas sampling mechanism, the core barrel (22) is started to be taken, the natural gas sampling mechanism is taken by the natural gas sampling mechanism, the natural gas core barrel;
④ pressure maintaining core stage, namely, after coring, throwing a fisher which is clamped in a groove at the top of a control rod (1), lifting a drilling tool, driving a coring barrel (22) to move upwards by the control rod (1), and moving the drilling tool integrally downwards relative to the control rod (1) under the action of self weight;
⑤ core freezing stage, during the drilling tool lifting process, the control valve top block (16) moves downwards relative to the control rod (1), when the control valve top block moves to the state that the lower surface of the control valve top block is flush with the upper surface of the top block chamber (17), the control valve top block (16) retreats into the top block chamber (17) under the action of downward pressure exerted by the control valve core (14), at the moment, the control valve core (14) seals the outlet at the lower part of the cold source cavity under the action of the pretightening force of the control valve spring (15) and the pressure in the pressure chamber, when the pressure in the pressure chamber is lower than 1MPa, the control valve core (14) compresses the control valve spring (15) under the action of the internal pressure of the cold source cavity, opens the cold source cavity, a cold source is injected into the annular gap between the pressure chamber and the core barrel (22), and the core of the natural gas hydrate in the core barrel (22) is frozen to below-40 ℃;
⑥ and a continuous drilling stage, namely, lifting the inner pipe assembly of the drilling tool to the hole opening to obtain the natural gas hydrate core, then, starting the pump, rotating the outer pipe (2) of the drilling tool to drive the drill bit (27) to continuously drill downwards to the stratum with the obtained natural gas hydrate core, and then, repeating the steps to continuously perform core drilling.
3. A hammer blow freezing pressure maintaining double acting rope sampling method for natural gas hydrate according to claim 2, wherein the cold source is a low temperature phase change liquid which adopts an alcohol-dry ice mixture with a temperature of 0 ℃ to-120 ℃, an acetone-dry ice mixture with a temperature of 0 ℃ to-130 ℃ or liquid nitrogen with a temperature of-197 ℃.
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