CN106988697B

CN106988697B - Freezing fidelity core drill of ocean natural gas hydrate

Info

Publication number: CN106988697B
Application number: CN201710234774.4A
Authority: CN
Inventors: 郭威; 张鹏宇; 贾瑞; 王元; 陈光华
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2017-04-12
Filing date: 2017-04-12
Publication date: 2021-06-18
Anticipated expiration: 2037-04-12
Also published as: CN106988697A

Abstract

A marine natural gas hydrate freezing fidelity core drill. Including outer tube assembly, inner tube assembly and salvage freezing assembly, the inner tube assembly is installed in the outer tube assembly, and the body of salvaging freezing assembly has heat preservation chamber, cold chamber and rock core chamber inwards in proper order, has a lifter in the rock core chamber, and the fishing hook is installed to the lifter lower extreme, and when salvaging freezing assembly and entering into outer tube assembly upper end, the fishing hook grabs the spearhead and promotes the inner tube assembly to the rock core chamber through shifting up of lifter. The whole inner tube assembly is positioned in the core chamber in the drill lifting process, the cold source reduces the temperature of the core in the core tube and inhibits the decomposition of hydrate, the drilling fluid at the bottom of the core chamber is solidified due to low temperature, certain pressure can be maintained in the core chamber, the hydrate in the core is not decomposed in the lifting process, and high-fidelity sampling is realized.

Description

Freezing fidelity core drill of ocean natural gas hydrate

Technical Field

The invention relates to a marine natural gas hydrate freezing fidelity coring drilling tool, which is suitable for the field of marine natural gas hydrate exploration, obtains a high-fidelity seabed natural gas hydrate sample, and has important significance for reservoir property analysis and resource evaluation.

Background

The natural gas hydrate is an ice-snow-like crystalline compound formed under a certain temperature and pressure condition, water molecules form a cage under the action of hydrogen bonds, and gas molecules (guest molecules) are filled in cavities of a water molecule crystal framework. The natural gas hydrate widely exists in permafrost zones and seabed, is a clean energy source due to huge reserves, and is considered as a potential energy source in twenty-first century. The natural gas hydrate is formed and exists in the environment of high pressure and low temperature, the drilling sampling of the natural gas hydrate has important significance for hydrate evaluation and exploitation, and according to the natural gas hydrate pressure-stabilizing characteristic curve, if the temperature or pressure condition changes beyond the equilibrium condition, the natural gas hydrate is decomposed, so that high requirements are provided for drilling coring work. At present, natural gas hydrate samplers at home and abroad mainly comprise two types: one is a heat-preservation pressure-maintaining sampler, and the other is a hole bottom freezing sampler. The heat-preservation and pressure-maintaining sampler adopts a ball valve to perform turnover and pressure maintaining, a pressure compensation device is used for maintaining the pressure in the core tube, and heat preservation is performed by using a heat-preservation material, so that the success rate of coring is low in practical application; the natural gas hydrate hole bottom freezing sampling method directly freezes a natural gas hydrate core at the hole bottom through an external cold source, and the temperature of the natural gas hydrate core is reduced to be lower than the equilibrium temperature to inhibit the decomposition of the hydrate, so that a hydrate fidelity sample is obtained.

Disclosure of Invention

The invention provides a marine natural gas hydrate freezing fidelity coring drilling tool according to the sampling principle of a marine natural gas hydrate hole bottom freezing technology, which adopts an active cooling mode to inhibit the hydrate in a rock core from being decomposed in the lifting process and is used for marine hydrate high fidelity sampling.

The invention relates to a marine natural gas hydrate freezing fidelity coring drilling tool, which comprises an outer pipe assembly and an inner pipe assembly, and is characterized by also comprising a fishing freezing assembly:

the upper end of the outer pipe assembly is provided with a spring clip stop head, the inner wall of the middle part of the outer pipe assembly is provided with a seat ring, the bottom of the outer pipe assembly is provided with a righting ring, and the lower end of the outer pipe assembly is provided with a drill bit;

the inner pipe assembly comprises a hollow core pipe, a claw spring is arranged at the lower end of the core pipe, a piston is arranged in a core pipe cavity, an emptying channel is arranged above an inner cavity of the core pipe, the upper end of the core pipe is connected with an elastic clamping frame through a bearing, an elastic clamp and a tension spring are arranged in the middle of the elastic clamping frame, a recovery pipe is sleeved outside the upper pipe and can move on the elastic clamping frame, a spear fishing head is arranged at the upper end of the recovery pipe, a suspension ring is arranged at the lower end of the upper pipe, and when the inner pipe assembly is arranged in the outer pipe, a boss at the lower end of the elastic clamp stopping head acts on the elastic clamp and the tension spring to limit the; the suspension ring is clamped on the seat ring to limit the inner pipe assembly to move downwards;

salvage freezing assembly and include a body, have a heat preservation chamber in the body, the heat preservation chamber has an inside cold storage chamber that stores up, and the cold storage intracavity side is the rock core chamber, has a lifting rod in the rock core chamber, and fishing hook is installed to the lower extreme of lifting rod, and when salvage freezing assembly entered into outer tube assembly upper end, fishing hook seizes fishing spearhead and promotes the inner tube assembly to the rock core chamber through shifting up of lifting rod.

The working process of the drilling tool of the invention is as follows:

1. putting the assembled inner pipe assembly into the outer pipe assembly and to the bottom of the hole, opening the elastic clamp under the action of the tension spring, and limiting the up-and-down movement of the inner pipe by the suspension ring, so as to perform direct coring drilling;

2. the core pushes a piston in the core barrel to move upwards along with the continuous footage of the drilling tool, and flushing fluid in the core barrel is discharged through an emptying channel until the core barrel is filled with the core barrel;

3. in the drilling process, assembling a salvaging freezing assembly, and injecting a low-temperature cold source into a cold storage cavity;

4. after completing the drilling of a round, a winch rope is adopted to lower the salvage refrigeration assembly, the lower end of the salvage refrigeration assembly enters the outer pipe assembly, the salvage spearhead is grabbed by the salvage hook, the elastic clamp is recovered under the action of the clamping groove at the upper part of the recovery pipe, after the recovery pipe is moved upwards to a certain distance, the elastic clamp is clamped by the clamping groove at the lower part, and the lower drilling tool is lifted up together. The lifting rod is lifted by a winch, the inner pipe assembly moves upwards along with the fishing hook, the claw spring 14 is clamped off the rock core, and the inner pipe assembly moves upwards into the rock core cavity.

4. The whole set of drilling tool ascends along with the lifting of the winch, and at the moment, the cold source in the freezing cavity cools the whole inner pipe assembly through heat transfer.

5. And lifting the drilling tool to a drilling platform, taking out the core, and placing the core in liquid nitrogen for detection and analysis.

According to the invention, the rock core is obtained through the claw spring, the rock core pushes the piston of the rock core tube to move upwards, the rock core is not polluted by drilling fluid in the footage process, the whole inner tube assembly is positioned in the rock core cavity in the drilling lifting process, the cold source reduces the temperature of the rock core in the rock core tube through heat transfer to inhibit the decomposition of hydrate, the drilling fluid at the bottom of the rock core cavity is solidified at low temperature, a certain pressure can be maintained in the rock core cavity, and the hydrate in the rock core is not decomposed in the lifting process, so that high-fidelity sampling is realized.

Drawings

FIG. 1 is a front view of an outer tube assembly and an inner tube assembly of the present invention.

FIG. 2 is a front view of the inner tube assembly of the present invention.

Fig. 3 is a front view of a fishing freezing assembly of the present invention.

Fig. 4 is a front view of the recovery pipe.

Fig. 5 is a left side view of the recovery pipe.

Legend:

1. the fishing spear comprises a fishing spear head, 2, an elastic clip stop head, 3, a spring pin, 4, a recovery tube, 5, a tension spring, 6, an elastic clip, 7, an elastic clip pin, 8, a bearing, 9, a seat ring, 10, an emptying channel, 11, a core tube, 12, a piston, 13, a limit ring, 14, a claw spring, 15, a drill bit, 16, an underreamer, 17, a centralizing ring, 18, a suspension ring, 19, an outer tube, 20, a cold source injection hole, 21, a lifting rod, 22, a heat preservation cavity, 23, a cold storage cavity, 24, a copper heat transfer layer, 25, a core cavity, 26, a spring, 27, a fishing hook, 28, a positioning shaft sleeve, 29, a positioning shaft, 30, a fishing hook spring pin, 31, a stopping pin, 32, a rivet, 33, a pressure release valve, 34, a lifting ring, 35, a fishing hook frame, 36, an elastic clip frame, 37, an elastic clip groove, 38 and a clamping groove.

Detailed Description

The upper end of an outer tube 19 of the outer tube assembly is provided with a bullet clip stop head 2 in a threaded manner, the lower end of the bullet clip stop head 2 forms a stop ring in the outer tube 19, the inner wall of the middle part of the outer tube 19 of the outer tube assembly is provided with a seat ring 9, the bottom of the outer tube assembly is provided with a righting ring 17, and the inner tube assembly is positioned in the vertical direction by the seat ring 9 and the righting ring 17 when entering the outer tube. A drill bit 15 is arranged at the lower end of an outer tube 19 of the outer tube assembly, and a reamer 16 is arranged on the outer wall of the lower end of the outer tube 19 of the outer tube assembly; circulation holes are annularly arranged on the righting ring 17 and the seat ring 9, and when the drilling tool is lowered to the bottom of the well, the circulation of flushing liquid from annular space gaps is changed into the circulation of flushing liquid through the circulation holes.

The inner pipe assembly comprises a hollow core pipe 11, a claw spring 14 is installed at the lower end of the core pipe 11, a piston 12 is installed in a cavity of the core pipe 11, a limiting ring 13 for preventing the piston from falling off is arranged below the core pipe 11, an emptying channel 10 is arranged above the core pipe 11, the upper end of the core pipe 11 is connected with a columnar elastic clamping frame 36 through a bearing 8, the elastic clamping frame 36 is sleeved with a recovery pipe 4, the recovery pipe 4 can move on the elastic clamping frame 36, a spearhead 1 is installed at the upper end of the recovery pipe 4, an elastic clamp 6 and a tension spring 5 are installed in the middle of the elastic clamping frame 36, a suspension ring 18 is arranged at the lower end of the elastic clamping frame 36, an inner pipe positioning mechanism is formed by a spring pin 3, a tension spring 5, the elastic clamp 6 and an elastic clamp pin 7, and when the inner pipe assembly is arranged in the outer pipe assembly, the elastic clamp 6 is opened by the tension spring 5 and is blocked by a blocking ring formed by the elastic clamp blocking. The suspension ring 18 is arranged below the bearing 8, and when the inner pipe assembly is arranged in the outer pipe assembly, the suspension ring 18 is blocked by the seat ring 9 to limit the inner pipe assembly to move downwards; the bearing 8 ensures that the core tube does not rotate along with the outer tube, and the disturbance to the core is reduced;

the fishing and freezing assembly comprises a pipe body, the pipe body is sequentially provided with an annular heat preservation cavity 22, an annular cold storage cavity 23 and a core cavity 25, the upper end of the annular cold storage cavity is provided with a pressure release valve 33 and a cold source injection hole 20, a lifting rod 21 is arranged in the core cavity 25, the upper end of the lifting rod is provided with a lifting ring 34 used for connecting a rope, the lower end of the lifting rod 21 is in threaded connection with a fishing hook frame 35, a fishing hook 27 is fixed on the fishing hook frame 35, the fishing hook 27 is in an X shape, the middle of the fishing hook 27 is hinged by a fishing hook spring pin 30 to form a bottom claw and an upper claw, the two upper claws are connected through a pin 32, and the pin 32; a thrust pin 31 is arranged below the upper jaw, a groove corresponding to the thrust pin 31 is arranged at the lower end of the core cavity 25, and the thrust pin and the groove form a positioning structure of the fishing hook 27. When the fishing and freezing assembly enters the upper end of the outer pipe assembly, the lower claw of the fishing hook 27 catches the fishing spear head 1, the upper part of the fishing hook 27 contracts inwards, the moving stop pin and the rock core cavity lose sealing and limiting, meanwhile, under the compression of the elastic clamping groove 37 on the upper part of the recovery pipe 4, the elastic clamp 6 is recovered, after the recovery pipe 4 moves upwards to a certain distance, the elastic clamping groove 38 on the lower part of the recovery pipe clamps the elastic clamp pin 7, the lower drilling tool is lifted into the rock core cavity together, and when the inner pipe completely enters the rock core cavity, the whole drilling tool is lifted to the wellhead together with the lifting ring 34.

The cold source mixture that this embodiment adopted is liquid nitrogen, low temperature, alcohol mixture, and during the low temperature state, dry ice melts in the mixture of low temperature state, and along with the rising of temperature, dry ice sublimes, and pressure rise in the cold storage chamber 23, and when pressure reached relief valve opening pressure, CO2 gas was spilled by relief valve 33.

In the embodiment, the heat insulation material is filled in the heat insulation cavity and used for reducing heat transfer between the cold storage cavity and the outside through the outer side pipe wall.

Claims

1. The utility model provides a freezing fidelity coring drilling tool of ocean gas hydrate, includes an outer tube assembly and an inner tube assembly, its characterized in that still includes a freezing assembly of salvage:

the upper end of an outer tube (19) of the outer tube assembly is provided with a spring clip stopper (2), the inner wall of the middle part of the outer tube (19) of the outer tube assembly is provided with a seat ring (9), the bottom of the outer tube assembly is provided with a righting ring (17), and the lower end of the outer tube assembly is provided with a drill bit (15);

the inner pipe assembly comprises a hollow core pipe (11), a claw spring (14) is installed at the lower end of the core pipe (11), a piston (12) is installed in a cavity of the core pipe (11), an emptying channel (10) is arranged above the cavity of the core pipe (11), the upper end of the core pipe (11) is connected with a bullet clamp frame (36) through a bearing (8), a bullet clamp (6) and a tension spring (5) are installed in the middle of the bullet clamp frame (36), a recovery pipe (4) is sleeved outside the bullet clamp frame (36), the recovery pipe (4) can move on the bullet clamp frame (36), a fishing spear head (1) is installed at the upper end of the recovery pipe (4), a suspension ring (18) is arranged at the lower end of the bullet clamp frame (36), and when the inner pipe assembly is arranged in an outer pipe (19), the inner pipe assembly is limited to move upwards by a boss at the lower end of the bullet clamp (6) and the tension spring (5) acting on the; the suspension ring (18) is clamped on the seat ring (9) to limit the inner pipe assembly to move downwards;

salvage freezing assembly and include a body, there is a heat preservation chamber (22) in the body, heat preservation chamber (22) inwards have one to store up cold chamber (23), store up cold chamber (23) inboard is core chamber (25), there is a lifter (21) in core chamber (25), salvage hook (27) are installed to the lower extreme of lifter (21), when salvage freezing assembly enters into outer tube assembly upper end, salvage hook (27) and grab spearhead (1) and promote the inner tube assembly to the core chamber through shifting up of lifter (21).

2. A marine natural gas hydrate freezing fidelity core drilling tool as claimed in claim 1, characterized in that the insulation cavity (22) and the cold storage cavity (23) in the fishing freezing assembly pipe body are annular.

3. A marine natural gas hydrate freezing fidelity coring drill as claimed in claim 1 or 2, wherein the upper end of the annular cold storage chamber is provided with a pressure relief valve (33) and a cold source injection hole (20).

4. The marine natural gas hydrate freezing fidelity coring drilling tool as claimed in claim 1 or 2, wherein the lower end of the lifting rod (21) is in threaded connection with a grappling hook frame (35), the grappling hook (27) is fixed on the grappling hook frame (35), the grappling hook (27) is in an X shape, the middle of the grappling hook is hinged by a grappling hook spring pin (30) to form a bottom claw and an upper claw, the two upper claws are connected by a pin (32), and the pin (32) is sleeved with a spring (26); a thrust pin (31) is arranged below the upper jaw, a groove corresponding to the thrust pin (31) is arranged at the lower end of the rock core cavity (25), and the thrust pin and the groove form a positioning structure of the fishing hook (27).