Method for extracting natural gas hydrate by using gas mixture of CO2 and H2

A technology of mixed gas and mixed gas, which is applied in the development of fluids, earth-moving drilling, wellbore/well components, etc., can solve the problems of low CH4 content, low industrial application value, and increase the overall cost, so as to improve the production efficiency. , Overcome the effect of low methane mole fraction and reduce mining cost

Inactive Publication Date: 2014-08-13
CHINA UNIV OF PETROLEUM (BEIJING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although CO 2 / N 2 The recovery efficiency of mixed gas is higher than that of gaseous CO 2 Replacement, liquid CO 2 Replacement, CO 2 Emulsion replacement has been greatly improved, but due to the injection of N in the gas 2 The content is high, resulting in CH in the produced gas 4 content is not high, and N 2 / CH 4 Difficult to separate, increasing the overall cost, leading to the acquisition of CH 4 Industrial application value is not high
[0005] The technical problems in the current exploitation and the cost of exploitation have become the bottleneck restricting the exploitation of natural gas hydrate in various countries

Method used

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  • Method for extracting natural gas hydrate by using gas mixture of CO2 and H2
  • Method for extracting natural gas hydrate by using gas mixture of CO2 and H2
  • Method for extracting natural gas hydrate by using gas mixture of CO2 and H2

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Embodiment 1

[0046] This embodiment provides a CO 2 and H 2 The method of gas hydrate recovery with mixed gas, using such as figure 1 Shown device, this device comprises gas-liquid separation device 1, CH 4 Steam reforming device 2, mixed gas separation device 3. The device communicates with the natural gas hydrate reservoir 4 . The gas-liquid separation device 1 is connected with the natural gas hydrate reservoir 4 through conventional methods, and the gas-liquid separation device 1 is connected with the CH 4 Steam reforming unit 2-phase communication, CH 4 The steam reforming device 2 is connected with the mixed gas separation device 3 through conventional methods, and the mixed gas separation device 3 is connected with the natural gas hydrate reservoir 4 through conventional methods.

[0047] The use of CO provided by this example 2 and H 2 The method for recovering natural gas hydrate with mixed gas comprises the following steps:

[0048] Firstly, the conventional decompression...

Embodiment 2

[0055] This example uses CO 2 and H 2 Experiments were carried out on the method of exploiting natural gas hydrate with mixed gas, and the effect of each mixed gas on CH was calculated. 4 The optimal recovery rate of hydrate and the H 2 highest recovery rate. The method mainly consists of three parts: hydrate sample preparation, depressurization gas injection, and displacement mining, and specifically includes the following steps:

[0056] Hydrate sample preparation: prepare CH at 271.2K to 273.2K, 8.0-10.0MPa 4 Hydrate samples;

[0057] Pressure-reducing gas injection: reduce the pressure to 3.0MPa (above the stable pressure of hydrate) through slow exhaust, keep the pressure constant, and inject the mixed gas (CO 2 and H 2 ) continuous injection of CH 4 In hydrate samples, to CH 4 Free CH in hydrate samples 4 The content is less than 2%;

[0058] Replacement mining: continue to inject the mixed gas to 5.0MPa, and start to enter the replacement stage; the mixed gas ...

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Abstract

The invention provides a method for extracting a natural gas hydrate by using a gas mixture of CO2 and H2. The method comprises the steps of: extracting, through a depressurized way, free gases in a natural gas hydrate mineral deposit until a pressure of the natural gas hydrate mineral deposit reduces to a balance pressure or to be 5%-10% greater than the balance pressure corresponding to a temperature of the hydrate mineral deposit; injecting a gas mixture A of CO2 and H2 into a natural gas hydrate settled layer to decompose the natural gas hydrate, replacing the gas mixture A so as to obtain CH4 and water; extracting, through the depressurized way, a gas mixture B formed by the CH4 released by replacement and residual gas mixture A; reforming the gas mixture B through water steam so as to obtain a gas mixture C of CO2 and H2; separating the gas mixture C to obtain hydrogen, and a gas mixture D of the CO2 and H4; circularly injecting the gas mixture D into the natural gas hydrate settled layer, continuing excavating the natural gas hydrate. The method for excavating the natural gas hydrate by means of depressurization and replacement disclosed by the invention can not only improve an excavation efficiency of natural gas, but also overcome shortages of a low molar fraction and hard separation of methane in extracted product, so that an extraction cost is reduced.

Description

technical field [0001] The present invention relates to a method using CO 2 and H 2 The invention discloses a method for exploiting natural gas hydrate with a mixed gas, belonging to the technical field of marine natural gas hydrate exploitation. Background technique [0002] Natural gas hydrate is a special form of natural gas. It has wide distribution, large scale and high energy density. It has attracted worldwide attention and is known as "future energy". The data shows that the amount of natural gas hydrate resources discovered in the ocean and tundra in the past two decades is particularly huge, and the organic carbon reserves are equivalent to twice that of the world's proven fossil fuels. In addition, hydrate has a high energy storage density, and produces very little residue and waste after combustion, making it an excellent green energy source. [0003] Most hydrate production methods are based on destroying the phase equilibrium conditions of hydrate, such as c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B43/22E21B43/40
CPCE21B41/0099
Inventor 孙长宇陈光进王晓辉孙漪霏李楠刘蓓杨兰英
Owner CHINA UNIV OF PETROLEUM (BEIJING)
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