JP2018080477A - Methane hydrate drilling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for drilling a methane hydrate present in a surface layer of a sea bottom and deposits effectively and transporting it on the sea.SOLUTION: A methane hydrate drilling system includes, for transporting solid drilled by a self-propelled drilling device to an ocean methane gas storage unloading platform, a transport tube which transports the solid from the self-propelled drilling device to a sea platform arranged in sea until immediate before a limit area of pressure and temperature where methane hydrate is dissolved, and a continuous type bucket conveyor device for transporting the solid from said sea platform to said ocean methane gas storage unloading platform.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a methane hydrate mining system for efficiently mining and transferring methane hydrate resources present in the surface layer and sediments of the seabed to the sea.

It has been confirmed that a huge amount of surface-type methane hydrate exists in the sea near Japan, and if it is efficiently mined, energy concerns can be eliminated.
Currently devised recovery methods for methane hydrate include undersea coal mine method, self-ejection recovery method, civil engineering method, heating method, decompression method, and chemical method.

The following submarine resource mining equipment has been developed as a method for recovering methane hydrate existing on the Sea of Japan side, and the methane hydrate being mined is partially gasified and released into the sea. Combined with a device to collect.
A mandrel with a cutter drill at the tip is attached to one end of the mining frame, a mining drive vehicle is connected to the other end, the mining drive vehicle is advanced around the mandrel, and the earth and sand are crushed with the mining frame. The inside conveyor transports seabed resources and mixed earth and sand to the ship or the coast, and gas that is gasified from the seabed resources is collected on a gas collection sheet. (For example, see Patent Document 1).

JP2014-122531A

In the preceding case (Patent Document 1) described above,
1. Density of methane hydrate mass is light and 0.91 g / cm ^3, the outer shape of the dish-shaped in the bucket has a round is unstable in the sea, methane hydrate suspended during the transfer of the mine-bucket arm-pan Or it is dissolved and gasified, and it is doubtful that there is no problem in transport.
2. Direct transfer from the sea floor to the sea seems to be efficient at first glance, but long conveyors are affected by ocean currents and stormy seas. Reduce the utilization rate.
3. The mining drive vehicle seems to be able to operate stably when a hole is fixed at the mining position in the center of the seabed, but when the mining drive vehicle moves to the mining frame or moves the mining site, the conveyor device Moving is a big deal.
Such a problem is considered.

  The present invention is intended to solve the problems of such a conventional configuration, and has a structure in consideration of the environment during mining without reducing the energy efficiency for recovery as much as possible. The purpose is to realize a low-priced methane hydrate mining system with high recovery efficiency and high mobility even in rough seas, such as by using a flexible tube to stabilize the water.

In order to achieve the above object, the methane hydrate mining system according to the first aspect of the present invention is a self-propelled mining equipped with a mining machine, a crusher, and a pressure feeder in excavating methane hydrate present on the seabed. Equipment,
When transferring solids sent from the self-propelled mining equipment to a methane gas storage and loading platform installed on the ocean,
A submarine platform suspended from the methane gas storage and loading platform in the sea immediately before the pressure / temperature limit region where methane hydrate dissolves, and a transfer tube for transferring to the submarine platform;
A continuous bucket conveyor for transferring from the subsea platform to the methane gas storage and loading platform;
It is characterized by comprising.

  In the methane hydrate mining system according to the second aspect of the present invention, the continuous bucket conveyor device collects methane gas generated by dissolving methane hydrate in the solid matter during the transfer of the solid matter. , Characterized by the provision of gas collection and transfer ducts for transfer to offshore methane gas storage and loading platforms.

  In the methane hydrate mining system according to the third aspect of the present invention, the transfer tube and the gas collection transfer duct use a fluid introduction type hollow hole forming tube, and a plurality of pipes constituting the fluid introduction type hollow hole forming tube are used. Seawater is pressed into the small-diameter hose and extended, and a part of the small-diameter hose continuously flows warm seawater below the sea surface toward the seabed.

  The methane hydrate mining system according to the fourth aspect of the present invention is characterized in that an intermediate stage is provided between the self-propelled mining device and the submarine platform. And

  The methane hydrate mining system according to the fifth aspect of the present invention is characterized in that the subsea platform is provided with a storage facility for storing the solid matter.

  In the methane hydrate mining system according to the sixth aspect of the present invention, the methane gas storage and loading platform is provided with a cylindrical structure depending from the methane gas storage and loading platform, and the gas collection and transfer duct and the structure are provided in the structure. A part of the continuous bucket conveyor device is incorporated.

As described above, the present invention is characterized by a transfer method that matches the characteristics of methane hydrate to be dissolved. The methane hydrate is mined on the crystalline seabed, and the tube is used until just before the pressure / temperature limit region where the crystal is dissolved. From the point just before the limit region to the methane gas storage and loading platform, it is a method of dealing with both crystal and gas states.
In addition, the methane gas storage and loading platform is provided with a vertical cylindrical structure, which is a spar type feature of the semi-submersible platform, to stabilize in rough seas and reduce the impact on mining and transfer, It is also excellent in terms of environment, such as complete recovery of leaking gas.

In addition, by installing an intermediate stage at a location suspended from the underwater platform, the self-propelled mining equipment can be operated efficiently without being affected by the sea.
In addition, by installing solid storage facilities on the subsea platform, the solid inventory will be adjusted in accordance with the operation of the self-propelled mining equipment, continuous bucket conveyor equipment, and offshore methane gas storage and loading platform, making the overall equipment more efficient. Operation is possible.

Furthermore, as a heat absorption measure when methane hydrate gas is dissolved, a fluid introduction type hollow hole forming tube is used for the transfer tube and the gas collection and transfer duct, so that the warm water near the sea surface is part of the hose constituting the tube. , And heat exchange with the low temperature seawater and solids in the tube transferred from the seabed can reduce the risk of clogging the tube due to recrystallization or the like during the transfer.
Furthermore, the methane hydrate recovered on the offshore recovery vessel can be made highly energy-efficient and recoverable by storing it in a high-pressure storage as it is in a lump shape utilizing its self-preserving characteristics.

FIG. 1 is a schematic diagram of a methane hydrate mining system. FIG. 2 is a schematic diagram of a self-propelled mining device. FIG. 3 is a schematic view of the subsea platform. FIG. 4 is a schematic diagram of a methane gas storage and loading platform. FIG. 5 is a schematic view of a fluid introduction type hollow hole forming tube. 6 is a cross-sectional view taken along the line AA ′ of FIG.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
The embodiment shown below exemplifies the methane hydrate mining system 1 for embodying the technical idea of the present invention, and is not intended to specify the present invention. It is equally applicable to those of other embodiments included in.

  Note that methane hydrate is decomposed by HYPERLINK "https://en.wikipedia.org/wiki/%E5%88%86%E8%A7%A3" \ o "decomposition" HYPERLINK "https: //en.wikipedia. org / wiki /% E5% 90% B8% E7% 86% B1% E5% 8F% 8D% E5% BF% 9C "\ o" Endothermic reaction "HYPERLINK" https: //en.wikipedia.org/wiki/%E6%B0%B7 "\ o" Ice "It forms a thin film of ice and is known to have a self-preserving property that can be stored for a long time even at -20 degrees under normal pressure. However, this is not considered in this embodiment.

FIG. 1 shows the overall configuration, and is a self-propelled mining device 2, an intermediate stage 3, an underwater platform 5 and storage equipment 51, a continuous bucket conveyor device 6, a self-propelled, which mine a surface type methane hydrate 911 on the seabed. Cylindrical structure that is suspended from the same equipment as the transfer tube 4 that connects the underground mining device 2 and the underwater platform 5, the gas collection and transfer duct 7 that contains the continuous bucket conveyor device 6, and the offshore methane gas storage and loading platform 8 An object 81, a methane gas folder 82 on the platform 8, and a gas loading facility 83 are configured.
The entire system is controlled by remote operation from the offshore methane gas storage and loading platform 8, and the power source of the facility is also sent from the facility.

FIG. 2 shows a self-propelled mining device 2 which is composed of a mining machine 21, a crusher 22, and a pressure feeder 23, and the mined solid material 91 is stored in the submarine platform 5 via the intermediate stage 3 via the transfer tube 4. It is transferred to.
Although the mining machine 21 depends on the situation and characteristics of the methane hydrate 911, the mining of the surface methane hydrate 911 includes a drum-type road cutter that cuts the surface of asphalt pavement, a drum chipper for crushing wood, a snowplow, etc. A machine that travels by excavating the surface at a depth of 50 to 100 mm is suitable.
Also, a cover for sending the excavated unstable methane hydrate 911 containing the methane 911 to the next process without scattering and an accumulation / sending port for the next process are provided.
Furthermore, the connection with the transfer tube 4 is preferably provided with a hose universal joint 25 that can freely rotate and turn to prevent twisting and breaking.
The self-propelled mining device 2 has already been developed, and any device can be used as long as it can be transferred to the transfer tube 4.

The transfer tube 4 to be transferred from the self-propelled mining device 2 to the underwater platform 5 may be a flexible tube or particularly a fluid introduction type hollow hole forming tube 92.
The fluid-introducing hollow hole forming tube 92 presses and expands seawater into a plurality of small-diameter hoses 923, and controls the straightness of the tube by controlling the small-diameter hose pressure. By the method of continuously taking in the lower warm seawater, heat can be exchanged with the low temperature seawater coming from the seabed, and clogging of the transfer tube 4 can be prevented.

In addition, the fluid introduction type hollow hole forming tube 92 is a double structure fluid introduction type hollow hole forming tube 92 in which another tube having a larger linear force than the size is provided outside the tube having a strong circular force as required. There is also a method of controlling the circular force and linear force of the tube to a higher degree by controlling the pressure applied to the tube.
It should be noted that since the degree of freedom in selecting the material, thickness and length of the hose and tubes, the number of hoses used, etc. is high, it may be set according to the conditions of the ocean to be mined.

  The intermediate stage 3 is fixed to the sea or the bottom of the sea hanging from the submarine platform 5. When the self-propelled mining device 2 moves by mining, the self-propelled mining device 2 moves to the transfer tube 4. This is intended to prevent the movement from being restricted by, for example, pulling other devices connected to the.

Further, when the pressure sending capacity of the pressure sending machine 23 provided in the self-propelled mining device 2 is insufficient, it is preferable to provide a reinforcing pressure sending machine 31 on the intermediate stage 3.
Furthermore, there is a method of sucking from the underwater platform side instead of a method of sending pressure to the underwater platform 5.

FIG. 3 shows an undersea platform 5 that is moored at a location suspended from the methane gas storage and loading platform 8 in the sea just before the pressure / temperature limit region where methane hydrate dissolves.
The underwater platform 5 is provided with a storage facility 51 for storing the solid material 91 transferred from the seabed by the transfer tube 4 and a continuous bucket conveyor device 6 for transferring to the offshore methane gas storage and loading platform 8.
Further, a gas collecting and transporting duct provided so as to enclose the continuous bucket conveyor device 6 is one in which the methane hydrate 911 of the solid substance 91 is dissolved and converted into methane gas during the transfer by the continuous bucket conveyor device 8. 7 and collected to the offshore methane gas storage and loading platform 8.
Since the density of the methane hydrate 911 is light and unstable at 0.91 g / cm ³ , a lid 61 is provided on the bucket so that the solid material 91 is not dissipated during the transfer by the continuous bucket conveyor device 6.

The gas collection and transfer duct 7 may be a flexible tube or particularly a fluid introduction type hollow hole forming tube 92.
The fluid-introducing hollow hole forming tube 92 presses and expands seawater into a plurality of small-diameter hoses 923, and controls the straight-line performance of the tubes by controlling the small-diameter hose pressure. By continuously taking and sending warm seawater below the sea surface, heat exchange with low-temperature seawater coming from the seabed is possible, and troubles such as clogging of the gas collection and transfer duct 7 can be prevented.

In addition, the fluid introduction type hollow hole forming tube 92 is a double structure fluid introduction type hollow hole forming tube 92 in which another tube having a larger linear force than the size is provided outside the tube having a strong circular force as required. There is also a method of controlling the circular force and linear force of the tube to a higher degree by controlling the pressure applied to the tube.
It should be noted that since the degree of freedom in selecting the material, thickness and length of the hose and tubes, the number of hoses used, etc. is high, it may be set according to the conditions of the ocean to be mined.

FIG. 4 shows a methane gas storage and loading platform 8 provided on the ocean. The methane gas storage and loading platform 8 has a function of receiving solid matter 91 and dissolved methane gas transferred from the underwater platform 5, and includes a methane gas folder 82 and a gas loading facility 83.
Moreover, depending on the case, the storage equipment for storing the solid substance 91 containing the methane hydrate 911 transferred in an undissolved state as a lump may be provided.
This is a characteristic of methane hydrate 911. HYPERLINK "https://en.wikipedia.org/wiki/%E5%88%86%E8%A7%A3" \ o "decompose" When decomposing, HYPERLINK "https : //en.wikipedia.org/wiki/%E5%90%B8%E7%86%B1%E5%8F%8D%E5%BF%9C "\ o" Endothermic reaction "HYPERLINK" https: / /en.wikipedia.org/wiki/%E6%B0%B7 "\ o" Ice "Forms a thin film of ice and is known for its self-preserving properties that can be stored for a long time in the form of lumps even at -20 degrees under normal pressure. If all of the gas is not dissolved even if it is transported, it is possible to reduce the cost by keeping the lump as long as it can be transported in the lump.

The continuous bucket conveyor device 6 is installed between the subsea platform 5 and the methane gas storage / loading platform 8. However, when all of the methane hydrate 911 in the solid material is dissolved during the transfer, this location is used. It is also possible to carry it up to and after that, only by the gas collection and transfer duct 7.
In addition, although the conveyor part becomes long as for the installation place of the submarine platform 5, if it is just before the pressure / temperature limit area | region where methane hydrate melt | dissolves, it can also be installed in the seabed.
In addition, since the undersea platform 5 can be installed at or near the seabed, the methane hydrate mining system 1 can be used not only for mining methane hydrate but also for mining other seabed resources.

  The methane gas storage and loading platform 8 is provided with a cylindrical structure 81 that hangs down from the methane gas storage and loading platform 8, and partially includes the continuous bucket conveyor device 6 and the gas collection and transfer duct 7, so that the methane hydrate mining system 1 The impact on mining and transfer in rough seas can be reduced to ensure stable operation, and double gas recovery can be used to deal with accidents and environmental issues.

DESCRIPTION OF SYMBOLS 1 Methane hydrate mining system 2 Self-propelled mining equipment 21 Mining machine 22 Crusher 23 Pressure feeder 25 Hose universal joint 3 Intermediate stage 31 Pressure feeder 4 Transfer tube 5 Submarine platform 51 Storage equipment 6 Continuous bucket conveyor device 61 Bucket with lid 7 Gas collection and transfer duct 8 Methane gas storage and loading platform 81 Cylindrical structure 82 Methane gas folder 83 Gas loading facility 84 Mooring line and chain 91 Solid material 911 Methane hydrate 92 Fluid introduction type hollow hole forming tube 921 Tube body 922 Large diameter hollow hole 923 Small diameter hose 9231 Small diameter hose (water for expansion)
9232 Small diameter hose (seawater for heat exchange)
9233 Small diameter hose (electric communication cable, etc.)
9239 Seawater and methane gas

Claims (6)

In excavating methane hydrate present on the sea floor, a self-propelled mining device equipped with a mining machine, a crusher, and a pressure feeder,
When transferring solids sent from the self-propelled mining equipment to a methane gas storage and loading platform installed on the ocean,
A submarine platform suspended from the methane gas storage and loading platform in the sea immediately before the pressure / temperature limit region where methane hydrate dissolves, and a transfer tube for transferring to the submarine platform;
A continuous bucket conveyor for transferring from the subsea platform to the methane gas storage and loading platform;
A methane hydrate mining system characterized by comprising:   The continuous bucket conveyor device includes a gas collection transfer duct for collecting methane gas generated by dissolving methane hydrate in the solid material during the transfer of the solid material and transferring it to an offshore methane gas storage and loading platform. The methane hydrate mining system according to claim 1 provided.   The transfer tube and the gas collection transfer duct use a fluid introduction type hollow hole forming tube, and seawater is pressed into and stretched to a plurality of small diameter hoses constituting the fluid introduction type hollow hole forming tube, and the small diameter hose is formed. The methane hydrate mining system according to claim 1, wherein a part of the water continuously flows the warm seawater below the sea surface toward the seabed.   The methane hydride according to any one of claims 1 to 3, wherein an intermediate stage is provided between the self-propelled mining device and the submarine platform. Rate mining system.   The methane hydrate mining system according to any one of claims 1 to 4, wherein the subsea platform is provided with a storage facility for storing the solid matter.   The methane gas storage and loading platform is provided with a cylindrical structure depending from the methane gas storage and loading platform, and the gas collection transfer duct and a part of the continuous bucket conveyor device are incorporated in the structure. The methane hydrate mining system according to any one of claims 1 to 5.

Images