JP2014159710A - Methane hydrate production facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excavation technology effective for excavating methane hydrate sealed in a sea bottom stratum.SOLUTION: A whole constitution of a methane hydrate production facility consists of a platform (facility storing pontoon) installed on a sea, an excavation facility for performing mobile excavation in a sea bottom, a pipe connecting the pontoon and the excavation facility to each other and recovering methane hydrate, connection wires, a power cable and the like. The pontoon is equipped with a power unit, a high-pressure pump unit for excavation, a lifting winch for a sea bottom excavator, a separation facility and the like, which can be positionally kept by anchors, respectively, and can be moved in a free direction. The sea bottom excavation facility has functions of a high-pressure water nozzle, an actuation cylinder, a two-directional mobile cylinder, a light oil separation sheet for flotation and the like. At a soft stratum with a sedimentary layer in the sea bottom, high-pressure water is injected into the stratum and soil sealing is released to recover methane hydrate by separation caused by density difference. At a hard stratum, a bit is attached to a tip of the high-pressure water nozzle and a rock mass is crushed to extract the hydrate.

Description

    It relates to excavation of methane hydrate buried in surface soil of deep sea floor.

    The accumulated fossil fuel (gas oil) drilling and extraction that humans have used in the past has become scarce, and in recent years new energy such as methane hydrate that is newly buried in the seabed and shale gas that is buried in a strong shale rock It's been found. However, the hydraulic destruction method has been developed and put into practical use for shale gas drilling, and human energy choices have increased further, but there is no effective mining technology for drilling methane hydrate buried in the seabed. Is desired. Conventional excavation methods include a method for separating and recovering gas by decompression by drilling holes in the casing of the methane hydrate-containing layer of the borehole oil well, but there are problems such as the necessity of improving efficiency. Similarly, methods such as heated gasification have been attempted, but none of them has a narrow gasification application range of methane hydrate and has not yet achieved the effectiveness of a realistic gasification drilling method.

Engineering Department, Methane Hydrate Development Section, “NEWS RELEASE Methane Hydrate Offshore Production Test (2012 Field Work) Start”, [online], January 29, 2013, Petroleum Natural Gas and Metal Mineral Resources Organization (JOGMEC), [Search February 1, 2013], Internet, <URL: http://www.jogmec.go.jp/news/release/docs/2012/newsrelease_130129.pdf> By Yamaoka Soichiro, “Can we do, meta-high resource development near Japan? Japan is at the forefront of the world with the“ decompression method ”,” [online], October 11, 2012, [February 1, 2013 Search], Nikkei Business Publications, Nikkei Business Online, Internet, <URL: http: //business.nikkeibp.co.jp/article/topics/20121009/237835/>

    The present invention relates to mining of methane hydrate buried in seabed soil. Methane hydrate has a density of about 0.9 and is smaller than the density of seabed soil, which is about 2, but it is not released naturally into the sea because it is enclosed in the seabed. On the other hand, a hydrate is formed under a certain low temperature and high pressure condition with a compound of methane and water. The gas can be filled with about 150 liters of methane gas per liter of water. In other words, methane hydrate excavation is buried in the seabed at a depth of 1000 to 5000 m, and many exist in submarine strata from several meters to several hundred meters. Therefore, in soft formations where the seabed is a sedimentary layer, methane hydrate can be recovered by separation due to density differences by injecting high-pressure water and releasing the soil filling. In hard formations, the rock can be destroyed with high-pressure water, hydrates can be pushed out, and used in combination with these.

    First is the problem of mining from the reserve. The submarine strata buried in methane hydrate exist on the deep sea bottom, and the substratum may be a lower layer such as a bedrock other than a soft sedimentary layer. In addition, deep sea drilling is required.

    The next issue is the recovery of excavated methane hydrate and transportation to the sea. All of these must operate continuously, mass production is possible and security can be ensured without harming the environment.

    On the other hand, methane hydrate is separated into gas and water if the temperature rises or the pressure decreases. That is, since the deep sea is low-temperature and high-pressure, it is a necessary condition for high-pressure water sampling without gasification while the hydrate of the viscous body is fluidized by the diffusion water and collected from the sea floor at high pressure.

    As shown in Fig. 5, for methane hydrate excavation, a high-pressure water nozzle of a necessary and sufficient length is used for soft strata, and underground irrigation is carried out by cylinder stroke, and methane hydrate and soil are separated and mined by strata destruction. I do. When rock drilling is required, such as when it is under a hard rock layer, excavation is carried out by a hydraulic impact drilling boring method in which a drill bit is attached to the nozzle tip to give vibration and rotation. And it collect | recovers to a marine trolley tank, density-separating and hold | maintaining a required pressure.

    On the other hand, the handling conditions of mined methane hydrate are that the pressure that does not gasify in normal temperature seawater is about 100 atmospheres or more, and the recovery of the collected methane hydrate to the sea is about 100 atmospheres or more of high pressure water of about 200 atmospheres or more. Recovered water above atmospheric pressure is required. Adopting a booster pump that recovers the energy of the recovered water (methane hydrate-containing water) discarded here is a technology necessary for energy-saving drilling. This is because a plunger pump connected to the same rotating shaft is used and the energy of recovered water is used as a drive source for the mining water pump.

    The pipes required for high-pressure water, both recovered water from the seabed and drilling water, can reduce the required quality of the inner pipe by the double pipe made of corrosion-resistant material designed to withstand higher pressure from the outside as shown in Fig. 2. Is economical. In addition, methane hydrate storage and transport on the sea storage during transport of tankers requires liquid transport that prevents gasification the same as mining and recovery conditions. In this case, it is necessary to handle in a high pressure state.

By adopting the invented structure shown in FIGS. 1, 3 and 4, it is particularly effective for mining methane hydrate buried in shallow sedimentary seabeds of several m to 10 m in the deep sea of 1000 to 2000 m often found in the sea near Japan. Performance can be demonstrated, and continuous strip mining with a width of 100 m is possible on a 10000-ton class trolley.
Furthermore, efficient liquefied natural gas production can be achieved by installing converter equipment that separates the decompressed gas with the barge equipment and re-compresses and liquefies after dehydration.

    A light oil levitation system for freely moving a large-scale undersea drilling facility can reduce the necessary weight generated by a concrete structure and the like, and enables the necessary movement for undersea drilling.

    In the submarine drilling equipment, the required depth of the high-pressure water injection nozzles arranged in two or more rows is increased, and the required deep injection can be achieved by extending the driving cylinder. This enables excavation of several hundred meters.

        The present invention relates to methane hydrate drilling of submarine resources. FIG. 1 is a basic configuration showing the best mode of the present invention. The objective is to collect methane hydrate that exists in the deep sea. The individual configuration consists of a platform (equipment storage trolley) installed on the sea and excavation equipment for moving excavation on the sea floor as shown in FIG. 4, a pipe for connecting methane hydrate and mining equipment as shown in FIG. It consists of wires and power cables. These are based on the trolley shown in FIG. 1 and 3 includes a power unit that covers all energy, a high-pressure water pump unit for excavation, a tower winch that moves up and down with the seabed excavator, methane hydrate and seawater collected from the seabed excavator The soil is separated, and if necessary, gas separation equipment is installed from the hydrate. Furthermore, the trolley has a tank for storing the produced hydrate and produced gas at low temperature and high pressure, and also has a function of transferring the produced gas from the storage tank to a tanker having a special low temperature and high pressure vessel at sea. Here, the trolley can be held in position by an anchor chain stretched around the sea floor and has the function of moving in any direction.

    The best submarine excavator shown in FIG. 4 is suspended from the bottom of the carriage and can be lifted and lowered by a wire rope hoisting machine and the buoyancy created by the light oil separation sheet for levitation and the seabed and the sea shown in FIG. The connecting device shown in FIG. 2 is a connecting device that enables raising and lowering and excavation. For mining methane hydrate, a high-pressure water pipe and a high-pressure discharge pipe that discharges the collected hydrate are required. Fig. 4 Submarine drilling equipment has a hydrate recovery high-pressure pump connected to the outer pipe of the double pipe, a soil high-pressure injection pipe and an operating cylinder using high-pressure water that can drive the injection pipe into the seabed soil. A two-way moving cylinder function that enables the hydraulic cylinder to move between the cylinder and the excavation frame is installed, and when moving, the entire load of the excavator needs to be adjusted. Features such as a separation sheet.

    FIG. 5 shows the details of the best high-pressure water driving and facility transfer functions. The nozzle driving piston in the driving cylinder is provided with a two-way check valve. Vibrating by switching high pressure water for driving and pulling out. If necessary, rotating the nozzle inserting piston with a rotating wing, up and down movement and static rotation. In addition, high-pressure water can be injected from the nozzle by generating vibration. Here, when the soil has a layer made of hard rock, the rock can be crushed by attaching a super steel bit or the like to the tip of the injection nozzle.

      The structure of the float that floats the trolley shown in FIGS. 1 and 3 is a structure that can be watertight with a hollow in the center, and when filled, the float is lowered from the trolley and is assembled by a joint that can be replaced and repaired. Dharma type with a thick lower part, a thin upper part from the sea surface part, a wave countermeasure, a donut-shaped interior made of foamed plastic that does not break water pressure, and is constructed to ensure the necessary buoyancy of the trolley. A reinforced plastic is suitable as the material.

    The light oil separator separation sheet shown in FIG. 4 is a three-layered sheet, and light oil such as alcohol is driven between two and three layers to obtain levitation force. Existing pumps and pipes are used for taking in and out of light oil. When not in use, it is stored and stored in a trolley.

    The double pipe shown in FIG. 2 is best used as a corrosion-resistant FRP pipe, and the pressure resistance of the inner and outer pipes is 200 atm. In the present invention, by making double pipes, the pressure resistance of the inner pipe is allowed twice when operated at the same time, the inner pipe is used for high pressure water necessary for excavation, and the outer pressure pipe is used for liquefaction conditions of methane at room temperature It is assumed that 100 atm transfer pressure is used.

1 shows the overall configuration of the present invention. The trolley is anchored, and the hydrate is separated by high-pressure water destruction by digging equipment in the deep sea, transferred to a pressure centrifuge by a submarine pump, methane hydrate and impurities such as seawater and soil. To separate. If necessary, the hydrate is depressurized and gas separation is simultaneously performed, and then repressurized to be liquefied. The necessary drilling water is supplied to the deep-sea drilling facility after pressurizing the necessary water such as separated seawater on the trolley. FIG. 1 shows a case where the buried methane hydrate is shallow within a few meters of the seabed. In this case, methane hydrate can be separated and recovered on the inner surface of the separation sheet by simply moving the fixed high-pressure nozzle. A high-pressure water pipe, a power power cable, and an instrumentation electric cable that connect a trolley and a drilling facility that operates in the deep sea. It is a pulling rope for moving the drilling equipment to the sea when necessary. Shows all facilities and location of the trolley. Drilling equipment will be attached to the lower part of the trolley, and it will surface when necessary and perform maintenance in the state shown. The carrier will be accompanied by a high-pressure water pump, seawater separator, high-pressure hydrate tank, etc. from the power plant. It is also possible to attach a gas separation facility. It is a submarine drilling facility. It has its own weight to withstand the high-pressure water driving load, and is equipped with excavation equipment and sends the mining hydrate to the sea with a recovery high-pressure transport pump. On the other hand, facilities for operating levitation force using light oil are also included. The structure of a high-pressure water driving nozzle is shown. It has functions ranging from simple nozzle driving of high-pressure water to vibration rotary excavation function and built-in equipment movement drive device.

Claims (4)

    This is a methane hydrate drilling facility buried in the deep sea floor. A trolley that can store the equipment can be held and moved by the seabed and anchor chain, fixed on the ocean, and suspended from the bottom of the trolley. The methane hydrate contained is separated from the soil by lowering the drilling equipment to the bottom of the deep sea and spraying high pressure water from the nozzle to destroy the soil with two types of high-pressure water tubes connecting the trolley and the drilling equipment. Hydrate separated and collected by soil precipitation is transported to the sea in a state pressurized by a high-pressure pump, and gas and water are separated or re-pressurized and cooled to liquefy by depressurization or heating as required by a barge facility. Offshore facilities that produce mining gas with dedicated tankers or submarine piping.     A marine equipment trolley that produces methane hydrate, and the submarine excavation equipment stored in the lower part of the hull keeps the height to be lifted to the sea. A trolley where a floating body with a structure in which a plastic foam that can sink water into a hollow shape and has sufficient buoyancy necessary for the trolley is wrapped around the thick lower part.     In a submarine drilling facility, the cylinder stroke internal pressure is always set by hydraulic valve driving by a check valve placed in the opposite direction to the driving cylinder that can be extended to a length that can obtain the drilling depth. A piston with a check valve is attached to a rotary drive wing, and the cylinder is driven up and down by alternately injecting high-pressure water and extraction high-pressure water. When necessary, a drilling bit is attached to the tip of the nozzle, and the injection nozzle is vibrated and rotated. The equipment has the function of moving the frame with a high-pressure cylinder placed on the frame with the driving cylinder being driven into the ground.     In the submarine excavation facility, in order to facilitate the movement of the seabed, a separation sheet is provided on the structural frame so that the floating force can be obtained by injecting light oil over a large area. A facility that allows the recovery pump to be used with a function by using a switching valve.

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