RU2554375C1 - Method to extract gas hydrates from bottom deposits and device to this end - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: according to the method upper layer of gas hydrate mass is melted gradually by heating gas hydrate mass in bottom sediments of a water body up to temperature of 50-60°C. Heating is made by a heating element made as blade edge located along diameter of a cargo container lowered from a flotation device. The flotation device is made as a mobile underwater vehicle with retractable tract in the form of a container equipped with blade edge in the bottom part connected to heating elements inside container. Stability of the mobile underwater vehicle is endured in regard to the bottom of the water body. Container is rotated and electric current is supplied to heating elements. Gas hydrate stratum is heated up to 50-60°C. The container is lowered with rotation to the gas hydrate stratum with provision of single-point recovery of hydrates from the above stratum in solid state.

EFFECT: reduced material and operational expenditures and ecological consequences at gas hydrate extraction territory.

2 cl, 1 dwg

Description

The invention relates to the production of methane and its homologues from near-surface accumulations of solid gas hydrates in the bottom sediments of lakes, seas and oceans. There are a number of gas hydrate development technologies, depending on where they occur. The thermal method of developing a gas hydrate deposit involves burning part of the hydrocarbon feed at its location using the generated hot products to warm the reservoir (Kreinin E.V. Non-traditional thermal technology for producing hard-to-recover hydrocarbon materials / E.V. Kreinin // Gas industry. - 2005 . - No. 3. - p. 22 [1]). Technologies and equipment for developing deposits and obtaining the target product have a number of features due to the localization of this natural formation.

Gas hydrates of bottom sediments of the seas and oceans are clathrate compounds formed under certain thermobaric conditions from water and gas. They relate to compounds of varying composition and outwardly resemble compressed snow. Due to its structure, a single volume of gas hydrate can contain up to 160-180 volumes of pure gas. In general, the composition of gas hydrates is described by the formula M · n · H ₂ O, where M is the gas hydrate forming molecule, n is the number of water molecules per one included gas molecule, and n is a variable number depending on the type of hydrate forming, pressure and temperature. In the 1960s, the first gas hydrate deposits were discovered in the north of the USSR. From this moment, gas hydrates begin to be regarded as a potential source of fuel. Gradually, their widespread distribution in the oceans and instability with increasing temperature is revealed. Currently, natural gas hydrates attract particular attention as a possible source of fossil fuels (Dyadin Yu.A. Gas hydrates / Yu.A. Dyadin. A.L. Gushchin // Soros Educational Journal. - 1998. - No. 3. - S. 35-64 [2]; Carroll J. Hydrates of natural gas / J. Carroll Lane with English M .: Publishing house Technopress. 2007. - 316 p. [3]).

The increase in human energy needs and the decrease in oil and natural gas reserves in the coming decades will have geopolitical consequences. Therefore, at present, a search is underway for new non-traditional sources of energy and methods for their economical production. Gas hydrates play an important role in this list, since there are huge promising gas hydrate areas in Russia, including at the bottom of marginal and inland seas. A known method of production and transport of gas from gas and gas hydrate offshore fields, including the extraction of natural gas by wells, its processing in a hydrated state using heat and transportation on a mobile vehicle to a device supplying gas to a consumer (patent RU No. 2198285, 02/10/2003 [4] ) The known method carries out the processing of gas on a vehicle in one group of containers with the simultaneous decomposition in another group of containers of carbonate hydrates of industrial waste and pumping the latter to the depths of the sea, ensuring its burial in a hydrated state, and the processing of produced gas and decomposition of carbon dioxide is carried out with using a heat balance between them.

The implementation of the known method is quite a costly enterprise, requires special expensive equipment for the production and transportation of produced gas. Pumping industrial waste to the depths of the sea is technically difficult and unsafe for the environment.

A known method of extracting gas hydrates from the ocean floor using a mining device in the form of a self-propelled combine with controls, communications, production and loading and a device delivering them to the surface in the form of a barge with vehicles and ascent to the surface (application RU No. 2004106857/03 , declared on March 9, 2004; published on August 20, 2005 [5]).

The known method requires complex construction and control equipment. The extracted gas hydrates during their transportation can lose a significant amount of hydrate forming gas and make the extraction of minerals expensive and unprofitable.

There is a method of producing gases (methane, its homologues, etc.) from solid gas hydrates in the bottom sediments of the seas, oceans, in which two pipe columns are immersed in the well of the identified gas hydrate formation drilled to its bottom, pumping and pumping. Natural water with natural temperature or heated water enters through the injection pipe and decomposes gas hydrates into a gas-water system, which accumulates in a spherical trap formed in the bottom of the gas hydrate formation. Another pipe string carries out the evacuation of gases from this trap, including combustible gases - methane and others (application RU No. 2005139956, declared. 20.12.2005; publ. 27.06.2007 [6]).

The disadvantage of this method is the need for underwater drilling, which is technically burdensome, costly and sometimes introducing irreparable damage to the existing underwater environment of the reservoir.

Also known methods of gas production (application RU No. 2008110909 A, 09/27/2009 [7], patent RU No. 2066367 C1, 09/10/1996 [8], patent RU No. 2292452 C2, 01/27/2007 [9], patent RU No. 2063507 C1 , July 10, 1996 [10], patent RU No. 2262586 C2, 10.20.2005 [11], copyright certificate SU No. 1792482 A3, 01/30/1993 [12], JP application No. 2001280055 A, 10/10/2001 [13], US patent No. 5713416 A, 02/03/1998 [14]) are materially costly and introduce environmental damage.

The ability to use any natural resource with the lowest material costs and technology that is environmentally friendly is an important state task.

The technical result of the known technical solution (patent RU No. 2412337 C1, 02.20.2011 [15] is to reduce material and operating costs, as well as reducing the environmental load on the territory of gas production.

The technical result is achieved in a known manner [15], in which the upper layer of gas hydrate accumulations is gradually dissolved in the water of the reservoir, which has the natural temperature of the reservoir and is not a saturated gas solution, with the formation of a solution of methane and its homologs. The supply of this solution to the surface is first forced, then due to the effect of gas lift. The method is carried out using a device with systems for supplying water and lifting the resulting water-gas mixture to the surface of the reservoir, which is made in the form of a bell, to the closed end of which there are pipes for supplying natural water and for pumping the resulting water-gas mixture. The feed water is distributed along the inner surface of the bell wall using thin pipes equipped with special hydrant nozzles at the end in the lower part of the bell for power supply of water in different directions.

Water is supplied to the pipes using equipment equipped with measuring instruments mounted on a floating platform or vessel. The supply of water to the pipes is also carried out using immersed equipment.

The resulting water-gas mixture of gas hydrates is pumped out through a system of pipes connected to a storage tank installed on a floating platform or vessel.

Dissolution of the upper layer of accumulations of gas hydrates is carried out under excess pressure. The feed water, which is not a saturated solution of methane in water, is first sent to special tanks located at the top of the bell. Of these, through thin pipes located along the inner wall of the bell, it flows evenly under pressure into the lower open part of the bell into two types of special hydrant nozzles (one with a hole directed along the bell wall, and others perpendicular to the wall inside the bell). At the end of the bell, the supplied water is sprayed (exits under pressure) through nozzle hydrants, eroding the bottom sediments and gas hydrates. In the inner space of the bell, fragments of gas hydrates, gas and a solution of methane in water are formed. Through a system of pipes for pumping, the resulting water-gas mixture is first forced to enter the surface of the reservoir. With a further rise in the presence of the gas lift effect, the gas flows up independently and goes to a special storage tank, from where it flows through the pipeline to its destination.

The main disadvantage of this method [15] is the high complexity due to the presence of underwater communications (pipe system, bell), articulated with a floating platform or vessel. In addition, mining can only be carried out under favorable weather conditions. Otherwise, the pipe system between the vessel and the bell will be subject to mechanical stress.

The objective of the proposed technical solution is to increase reliability in the underwater production of gas hydrates.

The problem is solved due to the fact that in the method of gas production from gas hydrates of the bottom sediments of a reservoir, which is characterized by the fact that they conduct a gradual dissolution of the upper layer of gas hydrate accumulations, in which, unlike the prototype [15], a gradual dissolution of the upper layer of gas hydrate accumulations is carried out by heating accumulations of gas hydrates in the bottom sediments of a reservoir to a temperature of 50-60 ° C, by means of a heating element made in the form of a cutting edge placed along the diameter of the cargo a tanker lowered from a floating vehicle made in the form of a self-propelled underwater vehicle with a retractable caterpillar track in the form of a container with a cutting edge in the lower part connected to the heating elements inside the container, ensure the stability of the self-propelled underwater vehicle relative to the bottom of the reservoir, the container is rotated and electric current is supplied on heating elements, heat the gas hydrate formation to 50-60 ° C, carry out the descent of the container with rotation into the gas hydrate formation to ensure solid hydrates from the said formation, and in a device for gas hydrates from gas hydrates in the bottom sediments of a reservoir, consisting of a swimming means, hoisting mechanisms and a working body, the swimming means are made in the form of a self-propelled underwater vehicle equipped with a retractable tracked a path, locking mechanisms to ensure a stable position of the swimming means relative to the bottom of the reservoir, a manipulator, articulated with a rotating column, allowing room column in the container and the rotation of the latter, a working body is designed as a container, a hollow body whose lower part is made as a cutting edge connected to the heating element placed within the hollow container body, the container on the vertical axis is formed with a hole for the column.

The method of gas production from gas hydrates is illustrated in the drawing.

In the drawing, the positions denote a swimming means 1, which is made in the form of a self-propelled underwater vehicle equipped with a retractable caterpillar track 2, locking mechanisms 3, a manipulator 4, articulated with a rotating column 5, containers 6 placed in a cartridge 7 made of a cylindrical shape, containers 6 are made also cylindrical in shape, while in their lower part the containers 6 are made in the form of a cutting edge 8 connected to heating elements 9 placed inside the hollow body 10 of the containers 6.

The swimming means 1, made in the form of a self-propelled underwater vehicle, is also equipped with a navigation and orientation system 11, propellers 12, a motion control system 13, a cargo compartment 14 for accommodating containers 6. Each container 6 is provided with a hole 15 along its vertical axis, into which by means of a manipulator 4 a rotating column 5 is inserted.

The manipulator 4, articulated with a rotating column 5 is a trigger mechanism.

The working body is made in the form of a container 6, the hollow body 10 of which in its lower part is made in the form of a cutting edge 8 connected to the heating elements 9 placed inside the hollow body 10 of the container 6. The complex for gas production from gas hydrates works as follows.

Swimming means 1, made in the form of a self-propelled underwater vehicle according to a given program, goes to the bed of the gas hydrate formation. Through the locking mechanisms 3 takes a stable position relative to the bottom of the reservoir. By means of the manipulator 4, a rotating column 5 is inserted into the first container 6, electric current is supplied to the heating elements 9. By means of heating elements 9, the formation is heated to 50-60 ° C.

Further, due to the rotation of the rotating column 5, the container 6 is rotated and lowered into the gas hydrate formation 16. After filling the container 6 by rotating the rotating column 5 in the opposite direction, the container 6 is lifted and placed in its regular place in the cargo compartment 14 of the swimming vehicle 1.

The swimming means 1, after being fully charged with solid gas hydrate, due to the presence of a retractable track path 2 installed on both sides, carries out the transportation of the extracted gas hydrate.

Gas hydrates can be produced pointwise and periodically in a limited area and renewed after some time, since near-surface hydrates will form again in the same area. This method of production allows minimal and area-limited changes at the bottom that do not lead to catastrophic and irreversible changes in the biocenosis of the reservoir.

Information sources

1. Kreinin E.V. Non-traditional thermal technology for the production of hard-to-recover hydrocarbons / E.V. Kreinin // Gas industry. - 2005. - No. 3. - from. 22.

2. Dyadin Yu.A. Gas hydrates / Yu.A. Dyadin, A.L. Gushchin // Soros Educational Journal. - 1998. - No. 3. - S. 35-64.

3. Carroll J. Hydrates of natural gas / J. Carroll. Per. from English M: Publishing House Technopress, 2007. - 316 p.

4. Patent RU No. 2198285, 02/10/2003.

5. Application RU No. 2004106857/03, declared 03/09/2004; publ. 08/20/2005.

6. Application RU No. 2005139956, the application. 12/20/2005; publ. 06/27/2007.

7. Application RU No. 2008110909 A, 09/27/2009.

8. Patent RU No. 2066367 C1, 09/10/1996.

9. Patent RU No. 2292452 C2, 01/27/2007.

10. Patent RU No. 2063507 C1, 07/10/1996.

11. Patent RU No. 2262586 C2, 10.20.2005.

12. Copyright certificate SU No. 1792482 A3, 01/30/1993.

13. Application JP No. 2001280055 A, 10.10.2001.

14. US patent No. 5713416 A, 02/03/1998.

15. Patent RU No. 2446983 C2, 04/10/2012.

Claims (2)

1. The method of extraction of gas hydrates of the bottom sediments of a reservoir, characterized in that the gradual dissolution of the upper layer of accumulations of gas hydrates, characterized in that the gradual dissolution of the upper layer of accumulations of gas hydrates is carried out by heating the accumulations of gas hydrates in the bottom sediments of the reservoir to a temperature of 50-60 ^o C by means of a heating element made in the form of a cutting edge placed along the diameter of the cargo container, lowered from the swimming means, made in the form of self bottom of the underwater vehicle with a retractable caterpillar track in the form of a container with a cutting edge at the bottom connected to the heating elements inside the container, ensure the stability of the self-propelled underwater vehicle relative to the bottom of the reservoir, rotate the container and supply electric current to the heating elements, warm the gas hydrate layer to 50- 60 ^o C, carry out the descent of the container with rotation in the gas hydrate formation with the provision of point extraction of hydrates from the said formation in their solid form. 2. A device for the extraction of gas hydrates of the bottom sediments of a reservoir, consisting of a swimming means, tripping mechanisms and a working body, characterized in that the swimming means is made in the form of a self-propelled underwater vehicle equipped with a retractable caterpillar track, locking mechanisms to ensure a stable position of the swimming means relative to the bottom of the pond, a manipulator articulated with a column that can rotate, and allowing the column to be placed in the container and rotate the latter, a working body is designed as a container, a hollow body whose lower part is made as a cutting edge connected to the heating element placed within the hollow container body, which vertical axis is formed with a hole for the column.

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