# US 8,783,364 B2 · Method for production, substitution, or mining of gas hydrate

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- Number: US 8,783,364 B2
- Document ID: US8783364B2
- Status: Granted
- Kind: B2
- Application number: 12/063,819
- Filed: 2006-08-25
- Published: 2009-02-05
- Granted: 2014-07-22
- Earliest claimed: 2005-08-26
- Assignees: Central Research Institute of Electric Power Industry
- Applicants: Yojiro Ikegawa
- Inventors: Yojiro Ikegawa
- Web page: https://patentgrep.com/patent/US8783364B2

## CPC

- C10L 3/06: Natural gas; Synthetic natural gas obtained by processes not covered by C10G, C10K3/02 or C10K3/04 {(liquefying by pressure and cold treatment F25J)}
- C07B 63/02: by treatment giving rise to a chemical modification
- C10L 3/108: {Production of gas hydrates}
- E21B 41/0064: {Carbon dioxide sequestration (storing fluids in porous layers B65G5/005)}
- E21B 43/164: {Injecting CO2 or carbonated water (in combination with organic material C09K8/594)}
- E21B 41/0099: {specially adapted for drilling for or production of natural hydrate or clathrate gas reservoirs; Drilling through or monitoring of formations containing gas hydrates or clathrates}
- Y02C 20/40: of CO2
- Y02P 90/70: Combining sequestration of CO2 and exploitation of hydrocarbons by injecting CO2 or carbonated water in oil wells
- C10L: FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS
- C07B: GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR (preparation of carboxylic acid esters by telomerisation C07C67/47; telomerisation C08F)
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A gas hydrate is produced by injecting guest molecules into voids in a layer of which temperature and pressure condition allows the guest molecules to cause to form hydrate, in a form of emulsion where liquid of the guest molecules is dispersed in water as minute particles having a size of less than a size of voids, and thereby dispersing the guest molecules uniformly into the voids in the layer.

## Claims

### Claim 1

A method for substitution of gas hydrates, comprising:
injecting an emulsion into voids in a layer, the emulsion comprising drops of a liquid of second guest molecules in water, the drops of liquid of the second guest molecules being dispersed in the water as drops having a size of less than a size of the voids in the layer, wherein hydrates of first guest molecules exist in the voids in the layer and the second guest molecules form hydrates under higher temperature and lower pressure conditions as compared with temperature and pressure conditions under which the hydrates of the first guest molecules form so that the hydrate of the first guest molecules in the voids is substituted by a hydrate of the second guest molecules.

### Claim 2 (depends on 1)

The method for substitution of gas hydrates according to claim 1, including controlling a heating value per unit volume of the emulsion by varying a ratio of the drops of liquid of the second guest molecules and the water in the emulsion.

### Claim 3 (depends on 1)

The method for substitution of gas hydrates according to claim 1, including controlling a production rate of the hydrate of the second guest molecules by varying the size of the drops of liquid of the second guest molecules in the emulsion.

### Claim 4 (depends on 1)

The method for substitution of gas hydrates according to claim 1, wherein the first guest molecules are CH4, and the second guest molecules are CO2.

### Claim 5

A method for mining of gas hydrate, comprising:
injecting an emulsion into voids in a CH4 hydrate layer as a heating agent for decomposing the CH4 hydrate in the voids to mine the CH4;
the emulsion comprising drops of liquid CO2 in water, the drops of liquid CO2 being dispersed in the water and having a size of less than a size of the voids in the CH4 hydrate layer.

### Claim 6 (depends on 5)

The method for mining of gas hydrate according to claim 5, including:
injecting the emulsion into voids in a further layer that is rested on the CH4 hydrate layer for forming a seal layer of CO2 hydrate;
the further layer being under temperature and pressure conditions under which the CO2 hydrate is formed; and
recovering CH4 gas by replacing CH4 hydrate with CO2 hydrate.

### Claim 7

A method for mining of gas hydrate, comprising:
injecting an emulsion into voids in a layer under the ground that is rested on a CH4 hydrate layer to form a seal layer of CO2 hydrate;
the emulsion comprising drops of liquid CO2 in water, the drops of liquid CO2 being dispersed in the water and having a size of less than a size of the voids in the layer, the layer being under temperature and pressure conditions under which CO2 hydrate is formed;
injecting the emulsion into voids in the CH4 hydrate layer for decomposing CH4 hydrate existing in the voids in the CH4 hydrate layer into CH4 gas by heat of reaction of CO2 hydrate formation; and
recovering the CH4 gas at the ground by collecting the CH4 gas from the seal layer.

### Claim 8

A method for mining of gas hydrate, comprising:
injecting an emulsion into voids in a first layer under the ground that is rested on a CH4 hydrate layer for forming a seal layer of CO2 hydrate;
the emulsion comprising drops of liquid CO2 in water, the drops of liquid CO2 being dispersed in the water and having a size of less than a size of the voids in the first layer, the first layer being under temperature and pressure conditions under which the CO2 hydrate is formed;
injecting the emulsion into voids in a second layer that is rested under the CH4 hydrate layer for decomposing CH4 hydrate existing in the voids in the CH4 hydrate layer from a lower side of the CH4 hydrate layer by raising the temperature of the second layer using heat of reaction of the CO2 hydrate formation;
recovering CH4 gas at the ground by collecting the CH4 gas from the seal layer, the CH4 gas being produced by decomposition of the CH4 hydrate; and
injecting the emulsion into the voids in the CH4 hydrate layer after mining of the CH4 hydrate for restoring the CH4 hydrate layer after mining of the CH4 hydrate by producing CO2 hydrate in the voids in the CH4 hydrate layer after mining of the CH4 hydrate.