阅读说明：本技术 一种浅层天然气水合物钻井装置、开采系统及方法 (Shallow natural gas hydrate drilling device, mining system and method ) 是由 思娜 王敏生 叶海超 耿黎东 于 2020-06-30 设计创作，主要内容包括：本发明公开了一种浅层天然气水合物钻井装置、开采系统及方法。所述装置包括：管柱、工具组合及喷射钻头；所述管柱为扁形管柱,管柱内部空间从上至下分隔成三层,上层为生产层、中层为海水注入层、下层为冷冻层；上层设置有抽水排砂泵,上层对应的管柱侧壁设置有单向排砂孔,管柱顶面外部设置有精细防砂层；工具组合为动力工具、测量工具、推进器、导向工具、近钻头信息传输及储存中的一种或组合；工具组合设置在管柱外壁靠近喷射钻头的位置；喷射钻头与管柱的海水注入层固定连接,喷射钻头上设置有喷嘴。本发明通过创新的钻井及开采形式进行浅层天然气水合物资源开采。避免常规油气钻井的常规作业流程,降低作业成本、提高作业效率。(The invention discloses a shallow natural gas hydrate drilling device, a shallow natural gas hydrate mining system and a shallow natural gas hydrate drilling method. The device comprises: a tubular string, a tool assembly and a jet drill bit; the pipe column is a flat pipe column, the internal space of the pipe column is divided into three layers from top to bottom, the upper layer is a production layer, the middle layer is a seawater injection layer, and the lower layer is a freezing layer; the upper layer is provided with a water pumping sand discharging pump, the side wall of the pipe column corresponding to the upper layer is provided with a one-way sand discharging hole, and the outer part of the top surface of the pipe column is provided with a fine sand prevention layer; the tool combination is one or combination of a power tool, a measuring tool, a propeller, a guiding tool and near-bit information transmission and storage; the tool combination is arranged on the outer wall of the pipe column close to the jet drill bit; the jet drill bit is fixedly connected with the seawater injection layer of the pipe column, and a nozzle is arranged on the jet drill bit. The invention carries out shallow layer natural gas hydrate resource exploitation through innovative drilling and exploitation modes. The conventional operation flow of conventional oil and gas drilling is avoided, the operation cost is reduced, and the operation efficiency is improved.)

1. A shallow gas hydrate drilling installation, the installation comprising:

a tubular string, a tool assembly and a jet drill bit;

the pipe column is a flat pipe column, the internal space of the pipe column is divided into three layers from top to bottom, the upper layer is a production layer, the middle layer is a seawater injection layer, and the lower layer is a freezing layer; the upper layer is provided with a water pumping sand discharging pump, the side wall of the pipe column corresponding to the upper layer is provided with a one-way sand discharging hole, and the outer part of the top surface of the pipe column is provided with a fine sand prevention layer;

the tool combination is one or combination of a power tool, a measuring tool, a propeller, a guiding tool and near-bit information transmission and storage; the tool combination is arranged on the outer wall of the pipe column close to the jet drill bit;

the jet drill bit is fixedly connected with the seawater injection layer of the pipe column, and a nozzle is arranged on the jet drill bit.

2. The drilling apparatus of claim 1, wherein:

the water and sand pump is symmetrically arranged at the two sides of the production zone close to the side wall of the pipe column.

3. The drilling apparatus of claim 1, wherein:

the fine sand prevention layer is arranged in the middle of the water pumping sand discharging pump.

4. The drilling apparatus of claim 1, wherein:

the nozzle on the jet drill bit is rectangular or circular.

5. The drilling installation of claim 4, wherein:

the rectangular nozzle is arranged in the middle of the jet drill bit, and the circular nozzles are symmetrically arranged on the upper side and the lower side of the rectangular nozzle.

6. The drilling installation of claim 4, wherein:

the number of the nozzles is 6-12.

7. A shallow natural gas hydrate production system using the drilling apparatus as claimed in any one of claims 1 to 6, the system comprising:

surface of water device, drilling equipment and remote control equipment.

8. The mining system of claim 7, wherein:

the surface installation comprises: the system comprises a drilling platform, a water suction pump, an injection pipeline, a high-pressure injection pump and blowout prevention equipment;

a pipe column in the drilling device is connected with a wellhead of the drilling platform;

the remote control device receives data information of the drilling device through cable transmission.

9. A natural gas hydrate production method using the system according to any one of claims 7 to 8, characterized by comprising:

(1) pumping seawater, injecting the seawater into the middle layer of the pipe column, and driving the pipe column to go down through jet drilling;

(2) the tool combination and the remote control equipment are used for assisting the running of the pipe column, so that the drilling scheme is adjusted in real time, and the intelligent drilling is ensured; after drilling, settling sand to ensure that the pipe column is firmly fixed;

(3) opening the upper top surface of the pipe column to expose the fine sand control layer, starting production, and optimally designing the pumping speed of the pumping and sand discharging pump according to the optimal speed of hydrate decomposition and the minimum input amount of silt; meanwhile, the water pumping and sand discharging pump is used for discharging the entered silt to the seabed from the shaft through the one-way sand discharging hole, so that the pollution to the seabed is minimized;

(4) during production, cooling fluid is injected into the lower layer of the pipe column or the cooling pipe column is adopted for cooling, so that the hydrate on the lower part of the pipe column is not decomposed.

(5) And decomposing and producing the produced hydrate from the production layer and conveying the hydrate to a wellhead.

10. A natural gas hydrate mining method as defined in claim 9, wherein:

in the step (2), the sand setting time is 0.5-1 day.

Technical Field

The invention relates to the technical field of natural gas hydrate development, in particular to a shallow natural gas hydrate drilling device, a shallow natural gas hydrate mining system and a shallow natural gas hydrate drilling method.

Background

At present, the amount of petroleum and natural gas resources is continuously reduced, and the development and utilization of natural gas hydrate resources as a strategic reserve resource with huge resource amount become a hot spot pursued by various countries and various large energy companies.

The current natural gas hydrate resource development engineering technology mainly depends on continuously developed and advanced oil and gas resource development engineering technology. Aiming at the development of marine natural gas hydrate resources, the deep water operation platform and the conventional drilling technology are used for drilling a reservoir stratum in the current pilot production. Then, the characteristic of natural gas hydrate resources is utilized, and the hydrate resources are decomposed by means of reducing reservoir pressure, increasing reservoir temperature, injecting hydrate inhibitors and the like, so that the purpose of exploitation is achieved.

In the aspect of the exploitation method, a depressurization method, a thermal excitation method and an inhibitor method are proposed abroad. The Zhou Zhuang of China proposes a solid fluidization method for academists. On the basis of the methods, the natural gas hydrate is continuously sampled twice in south China sea in 2017 in China, and a depressurization method and a solid fluidization method are respectively adopted, so that great progress of development and utilization of natural gas hydrate resources is achieved, and a solid step is formed.

The solid-state fluidization method of the Zhou defending academician aims at the sea shallow hydrate resource, utilizes conventional oil and gas drilling to slurry the hydrate resource at the seabed and then decomposes and recovers gas. However, because the compaction degree of the seabed shallow layer is insufficient, great challenges are caused to the drilling engineering technology including the processes of well cementation, drilling, orientation and the like, and the whole set of hydrate resource development and utilization engineering technology and equipment need to be further perfected, so that the adaptability to the hydrate resource is improved.

Chinese patent CN109751017A discloses a gas hydrate multi-well commingled production development system, which comprises a floating platform, a seabed multi-phase pump station, a wellhead multi-phase pump, a control manifold, a first pipeline, a second pipeline and a multi-port gas well, wherein the floating platform is connected with the seabed multi-phase pump station, the seabed multi-phase pump station is connected with a plurality of control manifolds through the first pipeline, the control manifold is connected with the multi-port gas well through the second pipeline, and the wellhead of the gas well is provided with the wellhead multi-phase pump.

Chinese patent CN109736769A discloses a frozen soil natural gas hydrate horizontal branch well pattern mining system and method, which comprises a main drilling well, a production area, a production well, an area multilateral well, a production area boundary, a filling body, a decomposition reinforcing area, a main drilling well horizontal section, a main drilling well vertical section, a branch well, a decomposition circle and an arch structure. The invention has the beneficial effects that: the multilateral well network can improve the pressure sensitivity of formation fluid and also provide more decomposition free surfaces for the natural gas hydrate; after the mining is finished, grouting operation is carried out to fill the cavities and the through cracks formed after the mining, the rock stratum arch structure is strengthened, potential environmental damage risks are reduced, and the division of production areas and the succession sequence among the production areas in the long-term production process are planned.

Chinese patent CN109695441A is a method for exploiting natural gas hydrate by microwave heating of a parallel horizontal well, belonging to the technical field of exploitation of natural gas hydrate. The method comprises the following steps: combining geological data, arranging a parallel horizontal well pattern for a target storage and matching well completion operation, performing depressurization exploitation through a horizontal well until no economic benefit exists after well completion, then arranging a ground supply system and an underground microwave heating system in a heat supply well, heating a natural gas hydrate layer through a microwave heater, and collecting natural gas and produced water from a production well; according to the invention, the reserve of movable natural gas hydrate is increased by arranging horizontal wells distributed in parallel to the target storage, the movable heating storage is realized by using the coiled tubing and the microwave heater, the optimized exploitation of the natural gas hydrate storage can be realized by changing the heating position, the heat output power and the water drainage and gas production speed, the gas production efficiency can be improved, and the economic benefit is increased.

The article of development and thinking of natural gas hydrate mining technology (Chinese oil exploration 2016.09) investigates and analyzes the current main natural gas hydrate mining methods, including conventional natural gas hydrate mining methods such as a depressurization method, a thermal excitation method, an inhibitor method and the like.

Literature key technology for pilot production of marine natural gas hydrates (petroleum exploration 201609 in china) this article analyzed and studied the conventional pilot production method that relied on oil and gas drilling and production and was used in the current pilot production process.

The methods proposed in the above patents and documents are in theoretical and experimental stages, and although trial production is performed by both the solid-state fluidization method and the depressurization method, they have many inadaptations, and further exploration of a more efficient and feasible system mining method is required.

At present, a matched engineering technology and an exploitation system applied to development and utilization of shallow hydrate resources do not exist.

Disclosure of Invention

The invention provides a shallow natural gas hydrate drilling device, a shallow natural gas hydrate drilling system and a shallow natural gas hydrate drilling method, aiming at overcoming the challenges caused by the specificity of a shallow hydrate resource deposit layer and effectively mining ocean shallow hydrate resources. The conventional operation flow of conventional oil and gas drilling is avoided, the operation cost is reduced, and the operation efficiency is improved.

One of the purposes of the invention is to provide a shallow natural gas hydrate drilling device.

The device comprises:

a tubular string, a tool assembly and a jet drill bit;

the pipe column is a flat pipe column, the internal space of the pipe column is divided into three layers from top to bottom, the upper layer is a production layer, the middle layer is a seawater injection layer, and the lower layer is a freezing layer; the upper layer is provided with a water pumping sand discharging pump, the side wall of the pipe column corresponding to the upper layer is provided with a one-way sand discharging hole, and the outer part of the top surface of the pipe column is provided with a fine sand prevention layer;

the fine sand control layer is formed by adding a film layer or a material capable of isolating silt outside the conventional sand control screen pipe, the conventional film layer or the material in the prior art can be adopted, the effect of isolating silt is achieved, the particle size range is determined by technical personnel according to actual conditions, and the aim of isolating silt is to achieve.

When the pipe column is lowered, the pipe column is closed, and when the production is started, the pipe column is opened by using a mechanical mode or a control pipeline mode, such as slips or a hydraulic switch, and the like, the upper top surface of the pipe column is opened, so that the fine sand prevention layer is exposed, and the gas production channel is opened.

The tool combination is one or combination of a power tool, a measuring tool, a propeller, a guiding tool and near-bit information transmission and storage; the tool combination is arranged on the outer wall of the pipe column close to the drill bit;

the jet drill bit is fixedly connected with the seawater injection layer of the pipe column, and a nozzle is arranged on the jet drill bit.

In a preferred embodiment of the present invention,

the water pumping sand discharging pumps are symmetrically arranged at the positions, close to the side wall of the pipe column, of the two sides of the production zone;

the fine sand prevention layer is arranged in the middle of the water pumping sand discharging pump.

In a preferred embodiment of the present invention,

the nozzle on the jet drill bit is rectangular or circular.

In a preferred embodiment of the present invention,

the rectangular nozzle is arranged in the middle of the jet drill bit, and the circular nozzles are symmetrically arranged on the upper side and the lower side of the rectangular nozzle.

In a preferred embodiment of the present invention,

the number of the nozzles is 6-12.

The invention also aims to provide a shallow natural gas hydrate exploitation system of the drilling device.

The system comprises:

surface of water device, drilling equipment and remote control equipment.

In a preferred embodiment of the present invention,

the surface installation comprises: the system comprises a drilling platform, a water suction pump, an injection pipeline, a high-pressure injection pump and blowout prevention equipment;

a pipe column in the drilling device is connected with a wellhead of the drilling platform;

the remote control device receives data information of the drilling device through cable transmission.

The invention also aims to provide a natural gas hydrate exploitation method adopting the system.

The method comprises the following steps:

(1) pumping seawater, injecting the seawater into the middle layer of the pipe column, and driving the pipe column to go down through jet drilling;

(2) the tool combination and the remote control equipment are used for assisting the running of the pipe column, so that the drilling scheme is adjusted in real time, and the intelligent drilling is ensured; after drilling, settling sand to ensure that the pipe column is firmly fixed;

in a preferred embodiment of the present invention,

in the step (2), the sand setting time is 0.5-1 day.

(3) Opening the upper top surface of the pipe column to expose the fine sand control layer, starting production, and optimally designing the pumping speed of the pumping and sand discharging pump according to the optimal speed of hydrate decomposition and the minimum input amount of silt; meanwhile, the water pumping and sand discharging pump is used for discharging the entered silt to the seabed from the shaft through the one-way sand discharging hole, so that the pollution to the seabed is minimized;

(4) during production, cooling fluid is injected into the lower layer of the pipe column or the cooling pipe column is adopted for cooling, so that the hydrate on the lower part of the pipe column is not decomposed.

Below the hydrate decomposition temperature, for example: the temperature is below 5 ℃ under 500m water column, the specific temperature depends on the pressure and temperature of the hydrate reservoir, and the temperature and pressure curve generated by the temperature and pressure curve can be met, and the temperature and pressure curve can be determined by technicians according to specific conditions.

(5) And decomposing and producing the produced hydrate from the production layer and conveying the hydrate to a wellhead.

The invention abandons the traditional oil gas rotary drilling and exploitation system, scatters in the unconsolidated formation of the shallow layer according to the distribution form of the shallow layer natural gas hydrate, has low formation pressure, and does not need expensive PDC drill bits and complex drilling fluid systems. Meanwhile, the current price of the natural gas produced by the natural gas hydrate resource is considered to be lower, so that the cost is reduced for subsequent commercial exploitation, the system adopts the flat pipe column, the water jet is utilized to jet the flat production pipe column, and after sediment is precipitated, the pipe column is compacted, the situations of movement, rotation and the like of a round pipe column are avoided, so that well cementation is not needed, and the operation cost is further reduced. And moreover, the flat pipe column can be combined with the resource distribution characteristics of the shallow hydrate, so that the contact area of the hydrate is increased, and the decomposition efficiency is improved. The flat pipe column adopted by the invention can be adjusted in shape according to actual conditions, such as wave shape, groove shape, chamfer angle rounding treatment at the corner of the pipe column and the like, and the shape can be changed at will, so that the pipe column can be contacted with hydrate reservoirs as much as possible. The pipe column is put in by using the jet drill bit, the pipe column is arranged at one time in a mode of drilling and putting in the pipe column at the same time, and the drilling, the production and the drainage integrated operation is carried out. The system mainly comprises an operation platform, a seawater extraction pump, a high-pressure injection pump, a blowout preventer, a downhole pipe column and the like.

The basic principle of the mining method is mainly based on the cementation of a shallow natural gas hydrate reservoir stratum and low compaction degree, an oil-gas drill bit is not needed in the drilling process, only fluid jet is used for sand washing, then the drilling is directly carried out with a casing, the drilling is similar to casing drilling in oil-gas drilling, the well forming efficiency is improved, and the operation cost is reduced.

The invention simultaneously adopts the mode of directly pumping seawater from the platform and utilizes the high-pressure pump to spray the seawater through the flat pipe column at high speed through the special drill bit for drilling, thereby avoiding the pollution of drilling fluid on the seabed and simultaneously reducing the cost.

The drilling pipe column is divided into three layers, wherein the middle layer is used for injecting seawater, jetting and drilling and putting the pipe column; the upper layer is used for exploiting natural gas hydrates, an electric submersible pump or a specially designed pump group is installed on the reservoir section, and water pumping and sand discharging are carried out. Pumping water can reduce pressure, hydrate pressure reduction exploitation is realized, and silt flowing into a pipe column in the exploitation process is directly discharged from the sea bottom through a pump. Production monitoring equipment can be installed in the layer and transmitted to the remote control platform in real time; and a cooling pipeline can be put into the lower layer or liquid nitrogen can be injected into the lower layer for freezing the lower stratum, so that stratum settlement caused by decomposition of a small amount of hydrate at the lower part of the pipe column and damage of the pipe column can be avoided, the seabed monitoring equipment can be installed, and information data can be transmitted to the remote control platform in real time.

The jet drill bit of the invention mainly utilizes seawater high-pressure jet flow to carry out jet drilling. And the drilling tool can be designed and installed in front of the drill bit according to requirements, and matched with directional, measurement, crawling, power and other downhole drilling tools. The drill bit may be left to the bottom of the well for plugging by ball dropping or other designs after the final drilling operation is completed.

ADVANTAGEOUS EFFECTS OF INVENTION

The invention carries out the exploitation of the shallow natural gas hydrate resource through the innovative drilling device and the exploitation system. The conventional operation flow of conventional oil and gas drilling is avoided, the operation cost is reduced, and the operation efficiency is improved.

Drawings

FIG. 1 is a schematic illustration of a shallow natural gas hydrate production system of the present invention;

FIG. 2 is a schematic view of a jet drill bit;

FIG. 3 is a schematic view of a tubular string configuration;

FIG. 4 is a schematic cross-sectional view of a tubing string;

FIG. 5 is a schematic side view of the tubing string;

description of reference numerals:

1-drilling platform 2-water pump 3-water injection pipeline 4-high pressure injection pump 5-blowout preventer

6-well mouth 7-sea surface 8-mud line 9-shallow unconsolidated formation non-hydrate 10-hydrate layer 11-pipe column

12-seawater injection pipe 13-power tool 14-measuring tool 15-propeller 16-guiding tool 17-near bit information equipment 18-jet bit 19-remote control platform

20-jet drill bit 21-circular nozzle 22-rectangular nozzle

24-seawater injection layer 25-production layer 26-freezing layer 27-water and sand pump 28-upper production pipe column side 29-middle and lower pipe body side 30-one-way sand discharge hole 31-fine sand prevention layer.

Detailed Description

While the present invention will be described in detail and with reference to the specific embodiments thereof, it should be understood that the following detailed description is only for illustrative purposes and is not intended to limit the scope of the present invention, as those skilled in the art will appreciate numerous insubstantial modifications and variations therefrom.

Example 1

A shallow natural gas hydrate drilling device.

The device comprises: a pipe string 11, a tool assembly and a jet drill bit 20;

the tubular column 11 is a flat tubular column, the internal space of the tubular column 11 is divided into three layers from top to bottom, the upper layer is a production layer 25, the middle layer is a seawater injection layer 24, and the lower layer is a freezing layer 26; the upper strata is provided with water pumping sand discharging pump 27, the tubular column lateral wall that the upper strata corresponds is provided with one-way sand discharging hole, tubular column top surface outside is provided with meticulous sand control layer 31, meticulous sand control layer 31 is the rete or the material that can keep apart more fine grain silt in the outside interpolation of conventional sand control screen pipe, it is confined when going down the tubular column, when beginning production, utilize modes such as machinery or control pipeline to open, open tubular column top surface on like slips or hydraulic switch etc. expose meticulous sand control layer, get through the product passageway.

The tool combination comprises a power tool 13, a measuring tool 14, a propeller 15, a guiding tool 16 and a near-bit information transmission and storage 17; the tool combination is arranged on the outer wall of the pipe column close to the drill bit;

the jet drill bit 20 is fixedly connected with a seawater injection layer 24 of the pipe column, and a nozzle is arranged on the jet drill bit 20.

The water pumping sand discharging pumps 27 are symmetrically arranged at the positions, close to the side wall of the pipe column, of the two sides of the production zone;

the fine sand control layer 31 is arranged in the middle of the water and sand pump 27.

The nozzle on the jet drill bit is rectangular or circular.

The number of the rectangular nozzles 22 is 1, the rectangular nozzles are arranged in the middle of the jet drill bit 20, the number of the circular nozzles 21 is 10, and the circular nozzles are symmetrically arranged on the upper side and the lower side of the rectangular nozzles 22.

Example 2

A shallow natural gas hydrate exploitation system of the drilling device.

The system comprises: surface of water device, drilling equipment and remote control equipment.

The surface installation comprises: the system comprises a drilling platform 1, a water suction pump 2, an injection pipeline 3, a high-pressure injection pump 4 and blowout prevention equipment 5;

a pipe column in the drilling device is connected with a wellhead of the drilling platform;

the remote control device receives data information of the drilling device through cable transmission.

The device comprises: a pipe string 11, a tool assembly and a jet drill bit 20;

the tubular column 11 is a flat tubular column, the internal space of the tubular column 11 is divided into three layers from top to bottom, the upper layer is a production layer 25, the middle layer is a seawater injection layer 24, and the lower layer is a freezing layer 26; the upper strata is provided with water pumping sand discharging pump 27, the tubular column lateral wall that the upper strata corresponds is provided with one-way sand discharging hole, tubular column top surface outside is provided with meticulous sand control layer 31, meticulous sand control layer 31 is the rete or the material that can keep apart more fine grain silt in the outside interpolation of conventional sand control screen pipe, it is confined when going down the tubular column, when beginning production, utilize modes such as machinery or control pipeline to open, open tubular column top surface on like slips or hydraulic switch etc. expose meticulous sand control layer, get through the product passageway.

The tool combination comprises a power tool 13, a measuring tool 14, a propeller 15, a guiding tool 16 and a near-bit information transmission and storage 17; the tool combination is arranged on the outer wall of the pipe column close to the drill bit;

the jet drill bit 20 is fixedly connected with a seawater injection layer 24 of the pipe column, and a nozzle is arranged on the jet drill bit 20.

The water pumping sand discharging pumps 27 are symmetrically arranged at the positions, close to the side wall of the pipe column, of the two sides of the production zone;

the fine sand control layer 31 is arranged in the middle of the water and sand pump 27.

The nozzle on the jet drill bit is rectangular or circular.

The number of the rectangular nozzles 22 is 1, the rectangular nozzles are arranged in the middle of the jet drill bit 20, the number of the circular nozzles 21 is 10, and the circular nozzles are symmetrically arranged on the upper side and the lower side of the rectangular nozzles 22.

Example 3

An innovative system and method for exploiting a shallow natural gas hydrate are composed of a water surface part, an underwater part and a remote control part.

The water surface equipment is mainly platform equipment and comprises a water suction pump, an injection pipeline, a high-pressure injection pump and blowout prevention equipment. Seawater is pumped into an injection pipeline 3 by a suction pump 2 and then injected into a downhole string through a high-pressure injection pump 4. The blowout preventer is mainly used for treating problems of shallow high pressure and the like, and can adjust or close a shaft in time to ensure safe operation.

The underwater equipment mainly comprises a downhole pipe column and a tool combination. Under the protection of the outer pipe body 11, the intermediate layer 12 is used for injecting seawater at a high speed, and downhole equipment such as a matched power tool 13, a measuring tool 14, a crawler/propeller 15, a guiding tool 16, a near bit information transmission and storage 17, a jet bit 18 and the like can be arranged and installed according to drilling requirements. The integrated drilling, mining and discharging pipe column with the special shape utilizes the middle layer 24 to inject high-pressure seawater, and the high-pressure seawater is sprayed and drilled through the 23-jet drill bit and is simultaneously put into the pipe column. Utilize upper strata tubular column 25 to exploit, because the water content of shallow hydrate reservoir is high, adopt pumping sand discharging pump 27 through the meticulous sand prevention layer 31 of opening upper strata production tubular column, according to the pumping rate of suitable pumping sand discharging pump 27, optimize the pumping rate of pumping sand discharging pump 27, maximize decompression exploitation efficiency. The water and sand pump 27 removes the silt entering the upper-layer pipe column 25 to the seabed through the one-way sand discharging hole. By utilizing the lower freezing layer 26, a cooling pipeline is arranged or cooling liquid is injected for cooling the hydrate in the lower stratum and preventing the hydrate from decomposing, so that the stability of the stratum below the pipe column is ensured, and the safety of the pipe column is ensured.

The remote control device 19 is mainly used for platform information management and control.

The hydrate mining method comprises the following steps:

the method comprises the following steps of installing an ocean platform 1, and installing a water suction pump 2, an injection pipeline 3, a high-pressure injection pump 4, a blowout prevention device 5 and a wellhead 6.

The sea water is pumped by a water pump 2, injected into the middle layer 12 of the pipe column 11 by a high-pressure injection pump 4 through an injection pipeline 3, and injected and drilled through the pipe column with an injection drill bit 18 to drive the pipe column to run in. The power tool 13 is used for providing underground power in the drilling process, the measuring tool 14 is used for collecting underground information, the crawler/thruster 15 is used for assisting the pipe column to be lowered in the long horizontal well drilling process, the drilling pipe column is accurately positioned through the guiding tool 16, the drill bit information device 17 in front of the near jet drill bit 18 is used for transmitting and receiving platform commands, the drilling scheme is adjusted in real time, and intelligent drilling is guaranteed. After the target layer is drilled, the drill bit is closed by using machinery or a control pipeline, or the middle layer is closed after the drill bit is recovered. In the process, any expensive drilling fluid and well cementation operation applied in the conventional oil and gas drilling process are not needed. After drilling, settling sand for a period of time to ensure that the drilling pipe column is firmly fixed.

And in the mining stage, opening the fine sand control layer 31 of the production layer 25 at the upper part of the special tubular column by using a mechanical mode or a pipeline control mode and the like to start production, and optimally designing the water pumping speed of the water and sand pumping pump 27 according to the optimal hydrate decomposition speed and the minimum sediment inlet amount. Meanwhile, the sand and mud entering the sand pump 27 are discharged from the shaft to the seabed through the one-way sand discharge hole 30, so that the pollution to the seabed is minimized.

In the exploitation process, in order to avoid the sedimentation of the pipe column in the hydrate layer in the production process, the principle of reducing the temperature of the stratum is adopted in the freezing layer 26 at the lower part of the special pipe column, cooling fluid such as liquid nitrogen is injected into the lower pipe column or the cooling pipe column is adopted for cooling, so that the hydrate at the lower part of the pipe column is not decomposed, and the stability of the pipe column is ensured.

The drilling and discharging processes and the seabed monitoring information can be monitored in real time through the remote control platform 19, and safe and efficient drilling, production and production are ensured.