WO2004009958A1

WO2004009958A1 - Apparatus and method for collecting underground hydrocarbon gas resources

Info

Publication number: WO2004009958A1
Application number: PCT/JP2003/009092
Authority: WO
Inventors: Tomoo Fujioka; Eiji Kogure; Toshio Kobayashi
Original assignee: Institute For Applied Optics Foundation; Japan Drilling Co., Ltd.
Priority date: 2002-07-22
Filing date: 2003-07-17
Publication date: 2004-01-29
Also published as: JP3506696B1; JP2004108132A

Abstract

Heat energy is sent without heat loss from the sea surface or land surface to a stratum containing methane hydrate, and the energy heats the methane hydrate so that methane gas is efficiently collected. An underground hydrocarbon gas resources-collecting apparatus is provided with a laser oscillator installed on a floating-type marine structure or on the ground, an optical fiber (1) inserted in a tube (2) that is guided to a stratum (B) containing methane hydrate, and means for supplying fluid (water, seawater, gas) to the stratum (B) through a gap between the tube (2) and the optical fiber (1). The stratum (B) containing methane hydrate is heated by laser beam to crush rock, and the methane hydrate is decomposed to separate methane gas. The methane gas and crushed rock are collected together with water or seawater.

Description

Description Underground renewable hydrocarbon gas resource collection device and collection method

The present invention relates to an apparatus and a method for collecting hydrocarbon gas such as methane gas from methane hydrate existing in the ground. Background art

Various underground resources including oil are buried in the ground, but methane hydrate has recently attracted attention as an underground resource.

In methane hydrate, a plurality of water molecules gather to form a cage such as a dodecahedron, a tetrahedron, or a hexahedron, and the methane molecule is confined in the cage to become one molecule, and the molecule is crystalline. Or they are randomly gathered.

This methane hydrate is found deep underground around the world, in rocks below the seabed and in Siberia. Notably, it has been confirmed that it is widely distributed under the seabed, such as off Shikoku, around Japan, and is expected as an energy resource.

+ Methane hydrate is formed under low pressure and high pressure. As shown in the phase equilibrium curve diagram in Fig. 8, the relationship between temperature and pressure is low. When methane hydrate is formed at the left side of the curve and the temperature is increased or the pressure is decreased (right side of the curve), it separates into methane gas and water.

In order to separate methane gas from methane hydrate, the phase must be on the right side of the phase equilibrium curve shown in Fig. 8. That is, at the same pressure, the temperature must be raised by several tens of degrees or more. In addition, 79 cals of heat energy per gram of ice is required as latent heat to dissolve in water from ice, and a large amount of heat energy is required to heat methane hydrate, including the heat of melting. .

As a method of collecting methane gas by supplying thermal energy to methane hydrate existing in the ground, drilling and drilling a hole in the seabed to the formation where methane hydrate is present, Send in hot water to remove methane hydrate A test method is being conducted in which the temperature of methane hydrate is raised by heating to collect vaporized methane gas.

According to this method, it is possible to collect a small amount of methane gas on a trial basis, but even if steam or hot water is sent from the sea, it will not reach the methane hydrate rate existing in the stratum several thousand meters away. Steam and hot water are cooled and heat energy is lost, making them extremely inefficient and not viable as an industry.

In addition, methane hydrate does not exist in the form of pools like oil, but is widely distributed in the ground in the form of solids. However, there is a problem that the method of sucking whole methane gas from there is not applicable.

Therefore, the present invention has been conceived to solve such a problem, and transmits heat energy from the sea or land to a stratum where methane hydrate is present without heat loss, thereby obtaining methane hydrate. The purpose is to heat the rate and collect methane gas efficiently. Disclosure of the invention

The underground gas resource collection device of the present invention, a floating marine structure or a laser oscillator installed on the ground, and a laser beam output from the laser oscillator

1

Equipped with a light guide fiber to the stratum containing methane hydrate and heating the stratum containing methane hydrate with a laser beam to separate methane hydrate to separate methane gas and float methane gas Is to collect.

The method of collecting gas resources underground according to the present invention is directed to a method in which a laser beam output from a floating marine structure or a laser oscillator installed on the ground is guided by an optical fiber to a stratum in which methane hydrate is stored. It heats the stratum containing methane hydrate, decomposes methane hydrate, separates methane gas, and collects floating methane gas. BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows the marine or marine gas used in the underground methane gas resource collection system of the present invention. Schematic diagram showing an embodiment of ground equipment,

FIG. 2 is a longitudinal sectional view showing a first embodiment of a pipe lowered into a stratum where methane hydrate is present and a distal end portion of a flexible tube passing through an optical fiber; FIG. Is a cross-sectional view showing reels at sea or ground equipment,

Fig. 4 is a characteristic curve showing the spectral characteristics of the transmission loss of quartz fiber.

FIG. 5 is a longitudinal sectional view showing a second embodiment of a distal end portion of a flexible tube passing through a pipe and an optical fiber,

FIG. 6 is a longitudinal sectional view showing a third embodiment of a distal end portion of a flexible tube passing through a pipe and an optical fiber,

FIG. 7 is a longitudinal sectional view showing a modification of the third embodiment of the distal end portion of the flexible tube passing through the pipe and the optical fiber.

FIG. 8 is a phase equilibrium curve diagram of methane hydrate. BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment)

Floating offshore structure (offshore equipment) Lower the drilling pipe from A to the seabed, and then excavate the formation under the seabed to formation B where methane hydrate is present to form a well. The formation of this well can be formed by the same technology as oil drilling.

As shown in FIG. 1, the underground renewable gas resource collection device of the present invention includes a floating offshore structure A, in which a pipe 3 is lowered into an excavated well. A device, a device for lowering a flexible tube 2 previously passed through an optical fiber 11 into a pipe 3, a reel 6 for winding the flexible tube 2, and a laser beam passing through the optical fiber 11. A laser oscillator ₄ for sending, a pump 5 for sending a fluid (water, seawater, gas) using a gap between the flexible tube 2 and the optical fiber 1, and a flow in a gap between the pipe 3 and the flexible tube 2. A floating object processing device 7 for separating methane gas from the floating object that floated through the road is provided.

As shown in Fig. 2, the pipe 3 is lowered to the well 9 excavated from the floating offshore structure A. At the end of this pipe 3, one central hole 32 and a circular array A block 31 having a plurality of holes 33 formed therein is attached.

Further, the flexible tube 2 previously passed through the optical fiber 1 is lowered into the pipe 3. A plurality of centering springs 34, which are bent in an arc shape, are attached near the tip of the flexible tube 2, and when the tip of the flexible tube 2 reaches the block 31 of the pipe 3, it is set to be acceptable. The distal end of the flexible tube 2 is guided to the center hole 32 of the block 31 so that the distal end of the flexible tube 2 projects below the block 31.

The distal end of the flexible tube 2 protects the distal end of the optical fiber 11, attaches a lens that focuses or diffuses the transmitted laser beam, attaches a prism that reflects laterally, or An irradiation nozzle 11 for directly irradiating without attaching any lens or the like is connected.

In the floating offshore structure A, the upper end of the pipe 3 is closed by the pulp 36 passing through the flexible tube 2, and the floating material rising in the pipe 3 is guided to the floating material processing device A via the valve 21. As if they were combined.

As shown in FIG. 3, in the floating type offshore structure A, the flexible tube 2 into which the optical fiber 11 has been previously inserted is wound around the reel 6 by a necessary and expected length. The fiber 1 and the flexible tube 2 are connected to the laser oscillator 4 and the pump 5 via a swivel 61 for coaxially connecting the fiber 1 and a flexible fiber swivel joint 62.

The optical fiber 11 transmits the laser beam output from the laser oscillator 4, and the flexible tube 2 sends a fluid (water, seawater, gas) using the gap with the optical fiber 11. The flexible tube 2 is configured to be ejected from the irradiation nozzle 11 at the tip.

As the laser oscillator 4, a chemically pumped Oxygene Iodine Laser (COIL), which chemically generates a laser beam in a wavelength range (1.0 to 1.3 m) where the transmission loss of quartz fiber is small, is referred to as COIL. ) Or a YAG laser device that generates a laser beam by electric energy is suitable. In other words, as is clear from the characteristic curve in FIG. 4 showing the spectral characteristics of the transmission loss of the quartz fiber, the laser beam of the wavelength (1.3 m) output from the iodine laser device and the wavelength (1.3 m) output from the YAG laser device ΐ '· 0 6 μ πι) Long distance transmission with loss.

It has been experimentally proved that a quartz fiber with a diameter of 0.6 mm can transmit a laser beam (energy) of 4 kW or more, and a quartz fiber with a diameter of l mm can be used to transmit more than 10 kW. It is possible to transmit a laser beam of several tens of kilowatts or more to a geological layer containing methane hydrate at a distance of more than 100 m if several quartz fibers are bundled. is there. As the optical fiber 1, a hollow fiber having a wide transmission band can be used. The hollow fiber has an inner wall coated with aluminum, silver or copper to form a reflective film. The use of an optical fiber with such a wide transmission band enables the transmission of a laser beam with an optimum wavelength that can be absorbed by various fluids fed in or a fluid generated in the stratum containing methane hydrate.

Next, a process of collecting methane gas using the methane gas resource collection device configured as described above will be described.

Pipe 3 descends from floating offshore structure A into well 9 formed by excavation to formation B where methane hydrate is present. This near the tip of the pipe 3, since the pipes. Packer ₃₅ is attached, by a pipe 'packer 35 is inflated by remote control to seal the gap between pipe 3 and the well 9. Further, the gap between the pipe 3 and the stratum can be sealed by the pipe / packer 35.

At the tip of the pipe 3, a block 31 having substantially the same outer diameter as that of the pipe 3 is attached. The block 31 has a hole 32 through which the flexible tube 2 passes through the core and a circular arrangement. A plurality of holes 33 serving as liquid or gas passages are drilled. ;

The flexible tube 2 passing through the optical fiber 11 wound on the reel 6 is pulled out and lowered in the pipe 3. Since a plurality of centering springs 43 bent in an arc shape are attached to the outer periphery of the distal end of the flexible tube 2, the distal end of the flexible tube 2 is connected to the center hole 32 of the block 31. The tip of the flexible tube 2 can be projected below the block 31.

By operating the laser oscillator 4, the laser beam of carpentry energy output from the laser oscillator 4 is transferred from the tip of the optical fiber 11 to a place where methane hydrate is present. Layer: When irradiating B and heating rock and methane hydrate, methane hydrate is decomposed and separated into water and methane gas.

The types of rocks that coexist with methane hydrate are sandstone, limestone, and shale.However, the energy of the irradiated laser beam causes it to be finely crushed and turned into powder. Produces any physical phenomenon. When the pump (5) is operated to eject a fluid (water, Kaiei, gas) from the tip of the flexible tube (2), the crushed rock is divided into a plurality of holes (33) arranged in a circle of a block (31) and a pipe. It rises with the separated methane gas through the flow passage in the gap between 3 and the flexible tube 2, and the rock can be easily removed.

The methane gas rising in the pipe 3 and the crushed rock are guided together with the fluid (water, seawater, and gas) to the floating material treatment device 7 installed in the floating marine structure A, where the methane gas is separated. Collected.

After passing through the optical fiber 11 with multiple reflections, the laser beam emitted from the tip of the optical fiber 11 tends to spread, but we want to irradiate the area near the tip of the optical fiber 11 more widely. In that case, a concave lens may be attached to the irradiation nozzle 11 at the tip of the optical fiber. .

Further, when it is desired to focus the laser beam emitted from the tip of the optical fiber 11 without diffusing, a convex lens may be attached to the irradiation nozzle 11 at the tip of the optical fiber.

The fluid (water, seawater, gas) supplied through the flexible tube 2 is jetted to the tip of the optical fiber 1, so that the tip (including the lens) of the optical fiber 1 is cleaned. In addition, the field of view of the laser beam can be secured.

As shown in the characteristic curve diagram in Fig. 4, water is emitted at the wavelength (1.3 m) output from the iodine laser device and at the wavelength (1.06 μπι) output from the YAG laser device. If the absorption is relatively low and within a few meters, the rock can be effectively irradiated through water. In addition, the contaminated water decomposed from methane hydrate is heated by a laser beam, and methane hydrate can be indirectly heated by the heated water (hot water). (Second embodiment)

In the first embodiment described above, the laser beam is irradiated in the same direction (vertically downward) as the pipe 3 descended into the well 9, but as shown in FIG. When the flexible tube 2 is projected obliquely downward using a block 31a in which the center hole 32 is bent obliquely downward as the block 31 to be attached to the tip of the underground, the rocks underground are inclined obliquely downward by the energy of the laser beam. It is possible to excavate.

(Third embodiment)

As shown in FIG. 6, an irradiation nozzle 11a provided with a prism 37 for reflecting a laser beam in the lateral direction is attached to the tip of the flexible tube 2. Then, a turbine that is rotated by a fluid (water, seawater, gas) supplied through the flexible tube 2 is provided, and the irradiation nozzle 11a is rotated. Can be irradiated.

Further, by exchanging the prism 37 provided in the irradiation nozzle 11a, it is possible to irradiate the laser beam at an arbitrary angle as shown in FIG.

Furthermore, when the flexible tube 2 is lowered while irradiating the beam of the laser beam in the lateral direction over the entire circumference, it is possible to excavate a large volume stratum. In the embodiment described above, the method of collecting methane gas from the geological layer B where methane hydrate is present using the floating type offshore structure A has been described. Methane gas can be collected. In addition, it is also possible to apply the irradiation nozzle 11a shown in FIG. 6 or FIG. 7 to the embodiment shown in FIG. Industrial applicability

As is clear from the description based on the above embodiment, according to the underground-recovered metagas resource collection device of this invention, the laser beam is applied to the deep stratum where methane hydrate is present with a small loss using an optical fiber. The transmission, that is, the energy for heating can be transmitted with high efficiency, so that the methane hydrate power, Methane gas can be collected efficiently, and the economic and practical effects are extremely large.

Claims

The scope of the claims

1. A floating marine structure or a laser oscillator installed on the ground, and an optical fiber that guides a laser beam output from the laser oscillator to a stratum containing methane hydrate. An underground gas resource collection system that heats a stratum containing methane hydrate, decomposes methane hydrate, separates methane gas, and collects floating methane gas.

2. A laser oscillator installed on a floating offshore structure or on the ground, and an optical fiber passed through a tube that guides the laser beam output from the laser oscillator to a stratum containing methane hydrate. Means for supplying a fluid to the formation through the gap between the tube and the optical fiber; heating the formation containing methane hydrate by the laser beam to pulverize rocks and decompose methane hydrate A methane gas separation device for collecting methane gas and crushed rock together with a fluid.

3. The underground gas as claimed in claim 1 or claim 2, wherein the laser oscillator is a COIL laser device that chemically generates a laser beam.

4. The underground gas resource collection device according to claim 1 or claim 2, wherein the optical fiber is a quartz fiber.

5. The underground renewable gas resource collection device according to claim 1 or 2, wherein the optical fiber is a hollow fiber.

6. A laser beam emitted from a floating marine structure or a laser oscillator installed on the ground is guided by an optical fiber to a stratum containing methane hydrate, and methane hydrate is applied by the laser beam. A method for collecting resources from underground resources, comprising heating existing strata, decomposing methane hydrate, separating methane gas, and collecting floating methane gas.

7. The laser beam emitted from the floating marine structure or the laser oscillator installed on the ground is guided to the methane hydrate-bearing stratum by the optical fiber passed through the tube, and Through the gap between Supplying the fluid, heating the stratum containing methane hydrate by the above laser beam to shatter the rock and decompose methane hydrate to separate methane gas, and collect methane gas and crushed rock together with the fluid. Underground gas resources collection method characterized by: