JP6396068B2 - Method for producing methane gas in the formation from coal and / or diatomite contained in the formation - Google Patents

Description

  The present invention relates to a method for producing methane gas from a coal and / or diatomite contained in a formation, and more particularly, to react a coal and / or diatomite contained in a formation with hydrogen peroxide in the formation. The present invention relates to a method for producing methane gas in a formation by a microorganism that produces a carbon compound and produces methane using the carbon compound as a substrate.

  Fossil fuels are a finite resource produced over hundreds of millions of years, but because the current economy and life of developed countries depend on fossil fuels, they are said to be depleted in the coming decades. The main fossil fuels currently in use include coal, oil, and natural gas. In recent years, the use of methane hydrate and shale gas has been studied, but the current situation is that the dependence on oil is high. However, as the consumption of oil has been increasing year by year, helping to expand the economy in developing countries, there is a particular concern about the early depletion of oil resources.

  As for coal, it accounts for about 30% of the world's primary energy and about 40% of power generation by power source, and it is said that the harvestable period is 133 years longer than other fossil fuels. It is considered as an important energy resource. However, compared to oil and natural gas, coal emits more carbon dioxide and NOx and SOx that cause acid rain when burned. Most of them rely on imports. Furthermore, in Japan, coal reserves in shallow coal seams shallower than 1200 m are said to be about 27 billion tons, whereas coal reserves in deep non-recoverable coal seams 1000 to 3000 m below 300 million tons and 3000 m There is a report that the coal reserves in deeper non-recoverable coal layers deeper than that are 3 trillion tons or more (Non-Patent Document 1).

  On the other hand, methane is a main component of natural gas extracted from oil and gas fields and useful as an energy source. Methane exists widely in nature and methane is produced by microorganisms in the underground environment. For example, in coal and diatomite (diatomite) layers, methane originating from microorganisms has been detected in various parts of the world (Non-Patent Document 2).

  Therefore, methods for producing methane using microorganisms have been developed. For example, red non-sulfur bacteria and hydrogen-utilizing methanogens that can be co-cultured in a medium containing no ammonium salt and containing L-cysteine hydrochloride as a reducing agent are co-cultured in the presence of carbon dioxide-containing gas. To obtain methane gas (Patent Document 1) and solubilize organic waste in a solubilization tank by adding high-temperature aerobic bacteria, and at the same time, feed the raw material that has been subjected to ammonia stripping to the methane fermentation tank Then, the method of fermenting methane with anaerobic microorganisms (Patent Document 2), after acid fermentation of biomass, methane fermentation to pressurize the residual mud containing residues of methane fermentation with gas, and then to normal pressure Method of producing methane using fractions containing residues that have been returned and floated for acid fermentation (Patent Document 3), the number of bacteria determined from the amount of DNA per unit volume of the sample collected from the methane fermentation broth Monitoring and controlling the number of archaea, a method of producing methane by fermenting biomass with methane fermentation-related microorganisms (Patent Document 4), heat treating seaweed to lower the molecular weight of skeletal polysaccharides and viscous polysaccharides Thereafter, a method of culturing methanogenic bacteria using heat-treated seaweed as a substrate to produce methane (Patent Document 5) can be mentioned. In addition, as a method for producing an organic substance that can be used by the methane-producing microorganism group, a method is disclosed in which hydrogen peroxide and coal are reacted to produce an organic substance of several tens% (up to about 80%) of the coal mass in a short time. (Non-Patent Document 3).

JP 2013-192547 A Japanese Unexamined Patent Publication No. 2011-083761 JP 2009-119361 A JP 2009-082825 A JP 2005-245443 A

Shimada S. et ai. , J .; MMIJ, 2010, Vol. 126, no. 1, pp602-607 Strapoc et al. , Annu. Rev. Earth Planet Sci. , 2011, Vol. 39, pp617-656 Miura et al. , Energy & Fuels, 1996, Vol. 10, no. 6, pp 1196-1201

  There is a method of producing methane by reacting coal or diatomite (diatomaceous earth), which is a long-lived fossil fuel, with hydrogen peroxide to produce organic matter, and using the produced organic matter to a group of methanogenic microorganisms. The method of producing methane by constructing a coal mine facility and reacting mined coal or diatomite (diatomaceous earth) with hydrogen peroxide and supplying the resulting organic acid to the methane-producing microorganism group is too expensive. Moreover, it can be assumed that the amount of methane that can be produced is limited, and it is difficult to say that this is an effective method for producing methane.

  Therefore, a method of generating methane underground and in the geological formation and recovering it as an energy resource is conceivable. However, in order to accelerate the methane generation process and recover it as an energy resource, a substance that can use methanogenic microorganisms from the source material is available. The decomposition process up to is a kinetic bottleneck. Several hypotheses seem to have been proposed for this methane production process, but the actual situation has not been proved experimentally. In the formation, except for special environments such as fault zones, the space where microorganisms can grow is very limited. Usually, microorganisms live in a few cracks in the formation, but when this crack is used as a bioreactor, there are limits to the contact efficiency between the organic substance and the microorganisms and the growth number of microorganisms. .

The present invention has been made to solve such problems, and coal and diatomite (diatomaceous earth) can be recovered by converting them into gas resources without going through a coal mining process. Coal and diatomite (diatomaceous earth) at difficult depths can be recovered as gas resources, and low-grade coal such as lignite can be recovered as gas resources, and methane gas is more combustible than coal. Production of methane gas from coal and / or diatomite contained in the formation, which can be recovered as an energy resource with less impact on the environment due to the small amount of CO ₂ , NO _X , and SO _X generated It aims to provide a way to do.

  As a result of diligent research, the present inventors have determined that the above-described decomposition process from a source material to a material that can be used by methanogenic microorganisms is a kinetic bottle in order to accelerate the methanogenesis process and recover it as an energy resource. Eliminates the bottleneck, the presence of cracks around the wells and wells, the injection of hydrogen peroxide solution from the wells, the formation of carbon compounds, the formation of spaces and the presence of methanogenic microorganisms, and even reduction It has been found that methane gas can be produced in the formation from coal and / or diatomite contained in the formation by injection of an agent and a basic solution, and the following inventions have been completed.

  A method of producing methane gas from coal and / or diatomite contained in the formation in the formation, the step of drilling from the ground toward the formation containing coal and / or diatomite, and the drilling as necessary. And a step of generating cracks around one or more wells obtained in the above, a hydrogen peroxide solution is injected from one or more wells obtained by the wells, and coal contained in the formation and / or Alternatively, diatomite and hydrogen peroxide are reacted to generate a carbon compound and a space is generated, and methane is formed from the one or more wells obtained by the wells as the substrate. A step of introducing a microorganism to be produced, and a micro-organism that produces methane from the carbon compound produced from the coal and / or diatomite remaining after the reaction as a substrate The step of inducing, said method comprising at least one step.

  The method according to (1), comprising a step of injecting a reducing agent from one or more wells obtained by the well.

  The method according to (1) or (2), comprising a step of injecting a basic solution from one or more wells obtained by the well.

  The step of drilling from the ground toward the formation containing coal and / or diatomite is a step of drilling from the ground toward the formation containing coal and / or diatomite using the hydraulic fracturing method (1) to ( The method according to any one of 3).

According to the method of producing methane gas from coal and / or diatomite contained in the formation according to the present invention, coal and diatomite (diatomaceous earth) are converted into gas resources and recovered without going through a coal mining process. In addition, coal and diatomite (diatomite), which are difficult to mine, can be recovered as gas resources. In addition, low-grade coal such as lignite can be recovered as a gas resource, and methane gas generates less CO ₂ , NO _x , and SO _x during combustion compared to coal, which has an impact on the environment. It can be recovered as a smaller energy resource. Further, in other countries, coal seam methane is regarded as an unconventional energy resource, and commercial production is actively performed. However, according to the present invention, a coal seam gas deposit that has been depleted can be regenerated.

Dissolved Organic Carbon (DOC) produced up to 100 days later in a reaction solution of Horonobe brown coal and ultrapure water (a) or a hydrogen peroxide solution (b) having a concentration of 0.3% (w / v) FIG. It is a graph which shows the density | concentration of the DOC produced | generated by 100 days after in the reaction solution of the pebble lignite and the ultrapure water (a) or the hydrogen peroxide solution (b) of density | concentration 0.3% (w / v). It is a graph which shows the density | concentration of the DOC produced | generated by 100 days after in the reaction solution of subbituminous coal and the ultrapure water (a) or the hydrogen peroxide solution (b) of density | concentration 0.3% (w / v). It is a graph which shows the density | concentration of the DOC produced | generated by 100 days after in the reaction solution of bituminous coal and the ultrapure water (a) or the hydrogen peroxide solution (b) of density | concentration 0.3% (w / v). . It is a graph which shows the density | concentration of the DOC produced | generated by 100 days after in the reaction solution of a diatomaceous mudstone and the ultrapure water (a) or the hydrogen peroxide solution (b) with a density | concentration of 0.3% (w / v). . The graph which shows the density | concentration of the acetic acid and formic acid which were produced | generated by 100 days after in the reaction solution of Horonobe brown coal and the ultrapure water (a) or the hydrogen peroxide solution (b) with a density | concentration of 0.3% (w / v). is there. In the graph which shows the density | concentration of the acetic acid and formic acid which were produced | generated by 100 days after in the reaction solution of a pebble lignite and ultrapure water (a) or a hydrogen peroxide solution (b) with a density | concentration of 0.3% (w / v) is there. The graph which shows the density | concentration of the acetic acid and formic acid which were produced | generated by 100 days after in the reaction solution of subbituminous coal and ultrapure water (a) or the hydrogen peroxide solution (b) with a concentration of 0.3% (w / v) is there. The graph which shows the density | concentration of the acetic acid and formic acid which were produced | generated by 100 days after in the reaction solution of bituminous coal and ultrapure water (a) or the hydrogen peroxide solution (b) with a concentration of 0.3% (w / v) It is. The graph which shows the density | concentration of the acetic acid and formic acid which were produced | generated by 100 days after in the reaction solution of the diatomaceous mudstone and the ultrapure water (a) or the hydrogen peroxide solution (b) with a density | concentration of 0.3% (w / v). It is. It was calculated from the acetic acid concentration and the formic acid concentration obtained from the reaction solution of Horonobe lignite, pebbled lignite, subbituminous coal or bituminous coal and hydrogen peroxide solution having a concentration of 0.3% (w / v) at 22 ° C. It is a graph which shows an assumed methane reserve. It is the graph which showed the production amount of the methane with the reaction solution of a concentration 1% (v / v) hydrogen peroxide or 1 mM acetic acid as a substrate, and H-RISE microorganisms were added to these together with the number of culture days. FIG. 5 is a graph showing the amount of methane produced together with the number of days of culture when a reaction solution of 3% (v / v) hydrogen peroxide or 4 mM acetic acid is used as a substrate and an H-RISE microorganism is added thereto. The amount of methane produced in each case of (A) no reducing agent + H-RISE microorganism, (B) reducing agent (cysteine) + H-RISE microorganism, and (C) reducing agent (sodium sulfide) + H-RISE microorganism. It is the graph shown with the culture days. (D) No reducing agent + H-RISE microorganism + diatomite (diatomaceous earth), (E) Reducing agent (cysteine) + H-RISE microorganism + diatomite (diatomaceous earth), and (F) Reducing agent (sodium sulfide) + H-RISE microorganism It is the graph which showed the production amount of methane with each culture | cultivation days in each case made into + diatomite (diatomaceous earth). (G) No reducing agent + H-RISE microorganism + brown coal, (H) Reducing agent (cysteine) + H-RISE microorganism + brown coal, and (I) Reducing agent (sodium sulfide) + H-RISE microorganism + brown coal. It is the graph which showed the production amount of methane with the culture | cultivation days.

  Hereinafter, a method for producing methane gas in the formation from coal and / or diatomite contained in the formation according to the present invention will be described in detail.

The first embodiment of the method for producing methane gas in the formation from coal and / or diatomite contained in the formation according to the present invention,
(I) A process of drilling from the ground toward a formation containing coal and / or diatomite (sakui process),
(II) a step of generating cracks around one or more wells obtained by drilling as necessary (crack generation step),
(III) A hydrogen peroxide solution is injected from one or more wells obtained by drilling and reacting coal and / or diatomite contained in the formation with hydrogen peroxide to produce a carbon compound. Steps for generating space (carbon compound / space generation step),
(IV) A step of introducing a microorganism that produces methane from one or more wells obtained by drilling using a carbon compound as a substrate, and methane from a coal and / or diatomite remaining after the reaction using a carbon compound as a substrate. At least one of the steps for inducing the microorganisms to be generated (microbe input / induction step)
The above steps (I) to (IV) are included.

  The present invention is “a method for producing methane gas from coal and / or diatomite contained in the formation”, that is, a method for producing methane gas from coal and / or diatomite contained in the formation in a closed underground space. It is. As described above, in the case of a method for generating methane in the underground, that is, in the formation and recovering it as an energy resource, it is preferable to recover the energy resource by accelerating the methane generation process. In addition to the kinetic bottleneck, the decomposition process up to the material has a very limited space where microorganisms can grow in the formation, except for special environments such as fault zones. Usually lives in a few cracks in the formation, but if this crack is used as a bioreactor, there will be a limit to the contact efficiency between the organic substance and the microorganism and the growth number of the microorganism. Although there are very difficult problems, these are solved by the steps (I) to (IV) of the first embodiment. That is, in the first embodiment, while effectively utilizing the underground closed space, the coal and / or diatomite contained in the formation is converted to a carbon compound, and the microorganisms are secured as it is in the underground closed space. This is a method for producing methane by generating and recovering methane.

  In general, “coal” means that after several thousand years to hundreds of millions of years ago, trees were subjected to corrosive action by microorganisms, and then subjected to mild temperatures and pressures of tens to hundreds of atmospheres in the ground. In the meantime, it has been changed to a natural organic polymer substance mainly composed of three elements of C, H, and O after undergoing dehydrogenation, demethane, and decarboxylation reactions, which are said to be coalification, Coal with 70 wt% or less is lignite, coal with 70 wt% to 77 wt% is lignite, coal with 77 wt% to 83 wt% is subbituminous coal, and coal is 83 wt% to 90 wt% Can be classified as bituminous coal and anthracite over 90% by weight. In addition to lignite, lignite, subbituminous coal, bituminous coal (bituminous coal), raw coal and anthracite, which are commonly called coal, wastes containing a large amount of carbon such as oil coke and carbon / graphite are included.

  "Diatomite (diatomaceous earth)" generally refers to soft rocks or soils mainly composed of diatom shells, mainly composed of silica, but also oxides of alumina, iron oxide and alkali metals in addition to silica. Etc. are often included. Moreover, since it has a porous material, it has a high porosity and has a cake bulk density of about 0.2 to 0.45.

  In the first embodiment, “saku well” in the drilling process of (I) refers to an operation of excavating a substantially cylindrical hole in the ground, and is used interchangeably with “boring” or “bore”. . In the first embodiment, the drilling method is not particularly limited. For example, in addition to a drilling method using a boring machine such as a rotary boring machine, a percussion boring machine, or a rotary percussion boring machine, a hydraulic fracturing method is used. The method of drilling using can be mentioned. In consideration of the necessity of the crack generation step (II), a method of drilling using a hydraulic fracturing method is preferable. In addition, the “stratum” in the well process of (I) refers to a strata that does not appear on the ground surface.

  In the crack generation step of (II), the method of “creating a crack” is not particularly limited. However, as described above, when drilling using the hydraulic fracturing method, a crack is generated using the hydraulic fracturing method as necessary. It is preferable to do so.

  In the carbon compound / space generation step of (III), the “hydrogen peroxide solution” is not particularly limited. For example, in addition to hydrogen peroxide solution, at least selected from the group consisting of methanol, ethanol, ethylene glycol, acetone, acetic acid and the like. A solution in which hydrogen peroxide is dissolved in one kind of organic solvent can be given, and a solution in which hydrogen peroxide is dissolved in a solvent in which these organic solvent and water are mixed can be mentioned. As the hydrogen peroxide solution, in addition to a commercially available aqueous hydrogen peroxide solution, it can be used by appropriately diluting it with water or the like, and, if desired, a normal solution such as iron sulfate, iron chloride, iron acetate, or iron nitrate. A solution obtained by adding an iron (II) salt of hydrogen peroxide to a hydrogen peroxide solution can be used.

  In the (III) carbon compound / space generation process, “injecting hydrogen peroxide solution” means that the hydrogen peroxide solution can be reacted with coal and / or diatomite contained in the formation from the ground. Although it is not particularly limited as long as it can be delivered to the surface, for example, in addition to an aspect in which the hydrogen peroxide solution is poured from one or more wells obtained by drilling, the hydrogen peroxide solution is added by an arbitrary medium. The aspect which can be delivered to the formation from the ground, the aspect which can be delivered to the formation from the ground in the form which sprays the hydrogen peroxide solution, etc. can be mentioned.

  In the carbon compound / space generation step (III), the “carbon compound” generally means an organic compound, an oxide such as carbon monoxide or carbon dioxide, a sulfide such as carbon sulfide or carbon disulfide, Inorganic carbon compounds including nitrides such as carbon nitride and halides such as carbon tetrachloride; ionic carbides such as calcium carbide, covalently bonded carbides such as silicon carbide, and carbon intrusions in crystal lattices such as transition metals Carbides including invasive carbides; carbonates such as calcium carbonate; cyanide compounds containing carbon such as potassium cyanide and dicyan; carbonyl compounds such as nickel carbonyl and dicobalt octacarbonyl; carbene complexes; Of these, the organic matter in the formation excluding methane and hydrogen peroxide completely Or, what appears to be due to an incomplete reaction or what is considered to appear. Examples of such carbon compounds include inorganic carbon compounds such as carbon monoxide and carbon dioxide; carboxylic acids such as formic acid, acetic acid and butyric acid, Alcohols such as methanol, ethanol, propanol, butanol and cyclopentanol, methylamines such as monomethylamine and dimethylamine, sulfides such as dimethyl sulfide and trisulfide, carbohydrates such as monosaccharides, oligosaccharides and polysaccharides, various amino acids, Carbonization of various proteins, lipids such as various fatty acids and aliphatic linear hydrocarbons, alkanes, alkenes, alkynes, water-soluble or fat-soluble aromatic hydrocarbons (for example, benzoic acid, benzene, alkylbenzene, xylene, toluene, etc.) Low content including hydrogen and humic and fulvic acids Or organic compounds of high molecular; can be mentioned.

  Further, in the carbon compound / space generation step of (III), “to generate a space” means that coal and / or diatomite contained in the formation is reacted with hydrogen peroxide, and the reaction causes coal and / or diatom. In addition to generating space by reducing rocks, space can be generated by reacting hydrogen peroxide with components other than coal and / or diatomite contained in the formation, or obtained by drilling. In addition, a case where a new crack or the like is generated by injecting the hydrogen peroxide solution from one or more wells and a space is generated is included.

  In the microorganism input / induction process of (IV), “microorganism that produces methane using a carbon compound as a substrate” refers to a microorganism that assimilate a carbon compound to produce methane, and as a result, methane as an initial substance. A combination of microorganisms (group of microorganisms) capable of producing Examples of such microorganisms were collected from the underground environment by the Horonobe Geo-Environmental Research Institute (commonly known as H-RISE), the Hokkaido Science and Technology Promotion Center (commonly known as Northtech Foundation). “H-RISE microorganism”, which is a methanogenic microorganism in which accumulation culture and subculture are repeatedly maintained for various methanogenic microorganisms, or previously reported (Shimizu et al., J. Environ. Biotechnol., Vol. 12, No. 1). , 2012), “microorganisms present in unsterilized coal and / or diatomite”, and the like.

Examples of the “H-RISE microorganism” include the following genus level microorganisms.
Archaea;
Methanosarcina, Methanosalsum, Thermicoccus, Methanoculus, Methanocorpusculum, Methanofollis, Methanobacterium, Thermoplasma,
Eubacteria;
[Firmicutes Gate] Acetobacterium, Alkalibacter, Alkaliphilus, Anaerosporobacter, Anaerotruncus, Anaerofilum, Anaerovorax, Bacillus, Blautia, Caldanaerobius, Caloramator, Clostridium, Christensenella, Dehalobacter, Dehalobacterium, Desulfotomaculum, Eubacterium, Erysipelothrix, Faecalibacterium, Flavonifractor, Geosporobacter, Desulfonispora, Gracilibacter, Hy rogenoanaerobacterium, Lutispora, Megasphaera, Mogibacterium, Moorella, Natronincola, Oscillibacter, Parasporobacterium, Papillibacter, Pelotomaculum, Pelospora, Peptoniphilus, Pseudoflavonifractor, Robinsoniella, Ruminococcus, Sedimentibacter, Soehngenia, Staphylococcus, Syntrophomonas, Tepidanaerobacter, Tissierella, Thermoanaerobacterium, Trichococc s,
[Bacteroidetes Gate] Alkaliflexus, Anaerohabdus, Bacteroides, Chryseobacterium, Meniscus, Palladibacter, Solitaire,
[Spirochaetes Gate] Spirochaeta, Sphaerochaeta,
[Actinobacteria Gate] Actinotalea, Atopobium, Cellulomonas, Conexibacter, Dietzia, Oryziumus, Rubrobacter, Streptomyces,
[Tenercutetes Gate] Acholplasma, Spiroplasma, Spiroplasma,
[Nitrospirae Gate] Leptospirillum,
[Dictylomi Gate] Dictyoglomus,
[Ruminobacillus gate] Ruminobacillus,
[Proteobacteria Gate] Acidithiobacillus, Acinetobacter, Alishewanella, Desulfomicrobium, Desulfuromonas, Desulfonatronum, Desulfovibrio, Geobacter, Halomonas, Hydrogenophaga, Pelobacter, Perlucidibaca, Pseudomonas, Serratia, Shewanella, Thiomicrospira

Furthermore, examples of the “microorganisms present in unsterilized coal and / or diatomite” include the following genus-level microorganisms.
Archaea;
Archaeoglobus, Methanoculleus, Methanobacterium, Methanobacteria, Methanolobus, Methanocorpusculum, Methanosarcina, Methanococcus, Methanocalculus, Methanocaldococcus, Methanothermococcus, Methanobrevibacter, Methanomethylovorans, Methanomicrobium, Methanotorris, Methermicoccus, Sulfophobococcus, Thermococcus,
Eubacteria;
[Proteobacteria Gate] Achromobacter, Acidiphilium, Acidocella, Acidovorax, Acinetobacter, Aeromonas, Afipia, Arcobacter, Aquaspirillum, Azoarcus, Campylobacter, Citorobacter, Comamonas, Burkholderia, Burkholderiaceae, Dechloromonas, Delftia, Desulfomicrobium, Desulfovibrio, Desulfuromonas, Desulfuromusa, Geobacter, Halomonas, Herminimonas, Hydrogenophaga, Jant inobacterium, Marinobacter, Massilia, Methylobacter, Methylocapsa, Methylotenera, Nitrincola, Novosphingobium, Pelobacter, PhylloBacterium, Pseudomonas, Ralstonia, Rhizobiales, Rhodobacter, Roseobacter, Sphingomonas, Shewanella, Stenotrophomonas, Sulfurospirillum, Syntrophus, Thiobacillus, Thiomonas, Variovorax,
[Bacteroidetes Gate] Bacteroides,
[Firmicutes Gate] Acetobacterium, Acidoaminobacter, Acloleplasma, Actinobacteria, Anoxynatronum, Bacillus, Clostridium, Desulfotomaculum, Dethiosulfatibacter, Exiguobacterium, Fusibacter, Geobacillus, Geobacillus, Geosporobacter, Nostocoida, Sedimentibacter, Soehngenia, Syntrophomonas, Thermotalea,
[Actinobacteria gate] Anthrobacter

  In the (IV) microorganism introduction / induction step, “inducing microorganisms” means that microorganisms adhering to coal and / or diatomite contained in the formation are used.

In the second embodiment of the method for producing methane gas in the formation from coal and / or diatomite contained in the formation according to the present invention, in addition to the steps (I) to (IV) described above,
(V) A step of injecting a reducing agent from one or more wells obtained by drilling (reducing agent injection step)
And have the steps (I) to (V) above.

  In general, the “reducing agent” is a substance that reduces other substances in the oxidation-reduction reaction and oxidizes itself. In the reducing agent injection step (V), methane in the case of using a carbon compound as a substrate is used. The organic reducing agent may be either an organic reducing agent or an inorganic reducing agent as long as it improves the methane production rate by the microorganisms that produce the organic reducing agent. Examples of the organic reducing agent include hydrazine. , Formaldehyde, methanol, citric acid and salts thereof (for example, sodium citrate, magnesium citrate), oxalic acid and salts thereof, glucose, ethylene glycol, L-ascorbic acid, alkylamines, arylamines, alkanolamines, Hydroxyamine, pyrrole, aniline, etc. can be mentioned, and examples of inorganic reducing agents include Sulfites such as sodium sulfite, potassium sulfite and ammonium sulfite; bisulfites such as sodium bisulfite, potassium bisulfite and ammonium bisulfite; sulfates such as cysteine and sodium sulfide; pyrosulfite, dithionite, Examples thereof include trithionate, tetrathionate, thiosulfate, nitrite, dimethyl sulfoxide, thiourea dioxide, phosphite, nitrogen-containing organic compounds such as amino acids and ethanolamine. These reducing agents may be used alone or in combination of two or more.

  Further, in the reducing agent injection step (V), “injecting reducing agent” is particularly an aspect that can be delivered to the reaction site of coal and / or diatomite and hydrogen peroxide and / or the periphery thereof. Although it is not limited, for example, in addition to the mode in which the reducing agent is poured from one or more wells obtained by drilling, the mode in which the reducing agent can be delivered from the ground to the formation by any medium, the reducing agent The aspect etc. which can be delivered to the formation from the ground in the aspect which sprays can be mentioned.

In addition, oxygen is generated by the reaction of coal and / or diatomite contained in the formation with hydrogen peroxide, and the underground becomes an oxidative environment, but the underground becomes reductive. There is a mechanism to restore the environment. For example, organic matter in the formation consumes oxygen in the oxidation reaction with oxygen and generates an organic acid, as well as pyrite (FeS ₂ ) in the formation as the oxygen concentration increases The reaction that suppresses the increase in the oxygen concentration as shown in the following reaction formula (i) due to the dissolution of A can be exemplified, but the step of inducing such a reaction is also included in the reducing agent injection step of (V). Is included.
(I) 2FeS ₂ + 2H ₂ O + 7O ₂ → 2Fe ₂ ⁺ + 2SO ₄ ²⁻ + 4H ⁺

The second embodiment of the method for producing methane gas in the formation from coal and / or diatomite contained in the formation according to the present invention is the above-described steps (I) to (IV) or (I) to (V). And
(VI) A step of injecting a basic solution from one or more wells obtained by drilling (basic solution injection step)
And (I) to (IV) and (VI), or (I) to (VI).

  In the basic solution injection step of (VI), as the “basic solution”, an acidic environment generated as a result of reacting coal and / or diatomite contained in the formation with hydrogen peroxide to form a carbon compound Is not particularly limited as long as it improves the methane production rate by microorganisms that produce methane when a carbon compound is used as a substrate. Examples of such substances include sodium hydroxide, water, and the like. Aqueous solutions such as potassium oxide and ammonia; aqueous solutions of alkali carbonates and alkali hydrogen carbonates such as ammonium carbonate, ammonium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate, potassium carbonate and potassium hydrogen carbonate; or ethanolamine, diethanolamine, formamide, etc. Examples include a solution containing a basic organic compound. Note that “injecting a basic solution” has the same meaning as “injecting a reducing agent” described above.

In addition, the reaction of coal and / or diatomite contained in the formation with hydrogen peroxide increases the hydrogen ion (H ⁺ ) concentration and lowers the pH of the underground, but suppresses the decrease in pH in the underground. For example, the pH buffering ability of bicarbonate ions and the dissolution reaction with minerals as shown in the following reaction formula (ii) or (iii) can be mentioned, but these reactions are induced. The step is also included in the reducing agent injection step (V).
(I) Hydrogen carbonate ions (HCO ₃ ⁻ ) in groundwater suppress the decrease in pH by the following reaction.
HCO ₃ ⁻ + H + → CO ₂ + H ₂ O
(Ii) Calcite (CaCO ₃ ) in the formation suppresses the decrease in pH by the following dissolution reaction.
CaCO ₃ + 2H ⁺ → Ca ²⁺ + H ₂ O + CO ₂

  Hereinafter, a method for producing methane gas in the formation from coal and / or diatomite contained in the formation according to the present invention will be described based on Examples. Note that the technical scope of the present invention is not limited to the features shown by these examples.

<Example 1> Generation of carbon compounds and calculation of assumed methane reserves (1) Generation of carbon compounds By oxidizing organic matter (Sedimentary Organic Matter: SOM) contained in coal and diatomite (diatomaceous earth), It is said that dissolved organic carbon (DOC) and organic acids (such as acetic acid and formic acid) that are carbon compounds are produced. Therefore, we examined whether DOC and organic acids (acetic acid and formic acid), which are carbon compounds, can be generated by reacting coal or diatomite (diatomaceous earth) with a hydrogen peroxide solution.

[1-1] Used coal and diatomite (diatomaceous earth)
Coal or diatomite (diatomite) used was lignite, subbituminous coal, bituminous coal, and diatomaceous mudstone. Ki), sub-bituminous coal is a sample collected in the mine of Kushiro Coalmine Co., Ltd. (Spring Mining Coal Formation, Paleogene), bituminous coal is a sample collected from the open-pit mining site of Sorachi Coal Co., Ltd. (Biei Samples (voice layer, Neogene) collected from Horonobe Underground Research Laboratory Center of Japan Atomic Energy Agency, respectively. Hereinafter, the lignites collected from Horonobe and pebbles outcrops are called "Horonobe lignite" and "Pebble lignite", respectively.

[1-2] Measurement of Organic Acid Concentration and pH Samples Horonobe lignite, pebbled lignite, subbituminous coal, bituminous coal and diatomaceous mudstone were each air-dried and then pulverized to a particle size of 106 μm or less using an automatic mortar. Put 0.5 g of the obtained powder sample into a 100 mL Erlenmeyer flask, add 75 mL each of ultrapure water or hydrogen peroxide solution with a concentration of 0.3% (w / v), and gently stir the reaction solution. Prepared, lightly covered the mouth of the flask with aluminum foil, and allowed to stand at room temperature (22 ° C.). These reaction solutions were periodically taken at 2.22 mL, and pH, DOC concentration, acetic acid concentration and formic acid concentration were measured. The DOC concentration of the reaction solution was measured by TOC-V _CSH (Shimadzu Corporation), and the acetic acid and formic acid concentrations were measured by 761 Compact IC (Metrohm). Table 1 below shows the pH value of the reaction solution of each sample and ultrapure water (MQ) and the pH value of the reaction solution of each sample and a hydrogen peroxide solution having a concentration of 0.3% (w / v). The DOC concentration, the acetic acid concentration, and the formic acid concentration in each sample are shown in FIGS.

[1-3] Test results As shown in Table 1, in pebble lignite and diatomaceous mudstone, the pH value and the concentration of 0.3% (w / v) when ultrapure water (MQ) was added were exceeded. It was shown that there was almost no difference from the pH value when the hydrogen oxide solution was added. Moreover, as shown in FIGS. 1-10, the DOC concentration, the acetic acid concentration, and the formic acid concentration in each sample are hydrogen peroxide having a concentration of 0.3% (w / v) than the reaction solution with ultrapure water (MQ). It was shown to be high in the reaction solution with the solution. In addition, the maximum value of the DOC concentration in the reaction solution with the hydrogen peroxide solution having a concentration of 0.3% (w / v) is about 350 mg / L for Horonobe brown coal as shown in FIG. 2 is about 80 mg / L for pebble lignite, about 70 mg / L for subbituminous coal as shown in FIG. 3, about 30 mg / L for bituminous coal as shown in FIG. 4, and diatomaceous matter as shown in FIG. It was about 30 mg / L in mudstone. Further, the maximum values of the acetic acid concentration and the formic acid concentration in the reaction solution with the hydrogen peroxide solution having a concentration of 0.3% (w / v) are about 10 mg / g and about 13 mg / g in Horonobe brown coal, respectively, as shown in FIG. g, about 3 mg / g and about 2 mg / g, respectively, for pebbles lignite as shown in FIG. 7, about 7 mg / g and about 2 mg / g, respectively, for subbituminous coal, as shown in FIG. 8, bitumen as shown in FIG. It was shown to be about 2.5 mg / g and about 1 mg / g for charcoal, respectively, and about 1.4 mg / g and about 0.7 mg / g for diatomaceous mudstone as shown in FIG.

  From the above results, it is possible to produce DOC and organic acids, which are carbon compounds, by reacting coal and diatomite (diatomaceous earth) with hydrogen peroxide solution. It has been clarified that the production amount of DOC and organic acid is expected to be increased by increasing the reaction time in the reaction between coal and diatomite (diatomaceous earth) and hydrogen peroxide solution.

(2) Calculation of estimated methane reserves Acetic acid obtained in a reaction solution of each sample in Example 1 (1) [1-2] and a hydrogen peroxide solution having a concentration of 0.3% (w / v) and Estimated methane reserves were calculated using the concentration of formic acid and the following formula. The result is shown in FIG.
CH ₃ COOH → CH ₄ + CO ₂
4HCOOH → CH ₄ + 3CO ₂ + 2H ₂ O

As shown in FIG. 11, the assumed methane reserves on the 100th day of the reaction are 3.7 m ³ / t for Horonobe lignite, 0.92 m ³ / t for pebbled lignite, 1.7 m ³ / t for subbituminous coal, and bitumen. The charcoal was 0.60 m ³ / t. In the case of diatomaceous mudstone, it was 0.32 m ³ / t (not shown).

It has been reported that gas reserves in common shale gas deposits are 0.5-3 m ³ / t and gas reserves in coalbed gas deposits are 0.8-15 m ³ / t (Jenkins et al., J. Pet). Technol., February (2008), pp 92-99). From the report and the above results, it is clear that the assumed methane reserves in the formation containing coal and / or diatomite (diatomaceous earth) are comparable or close to the reserves in the coal bed gas deposit and the shale gas deposit. became.

<Example 2> Preparation of organic acid in closed space and generation of methane using microorganisms In a closed space where oxygen was cut off, coal and / or diatomite and hydrogen peroxide solution were reacted to generate a carbon compound. Later, it was examined whether methane could be produced using microorganisms.

(1) Preparation of sample As coal or diatomite used, lignite collected from the riverbed outcrops of No. 223 of Teshio Forest on June 10, 2011 and June 23, 2013 was used. These lignites were vacuum packed immediately after collection and stored at 4 ° C. until used for experiments. Immediately before the experiment, these brown coals were crushed to 0.5 mm or less using an autoclave-sterilized stainless steel mortar or chisel, and weighed 5 g each to prepare a sample.

After the sample was stored in a 100 mL vial bottle that had been sterilized by dry heat at 180 ° C. for 2 hours in an anaerobic chamber, 50 mL of the basal medium described above was added and sealed with an autoclave-sterilized aluminum seal. Subsequently, using an anaerobic gas replacement device, the head space was almost completely replaced by repeating the depressurization and pressurization five times with an N ₂ —CO ₂ mixed gas having a volume ratio of 4: 1.

(2) Microorganisms used for culturing [2-1] H-RISE microorganisms Hokkaido Science and Technology Promotion Center (commonly known as Northtech Foundation) Horonobe Geosphere Research Institute (commonly known as H-RISE) The methanogenic microorganism maintained by repeated accumulation and subculture of various methanogenic microorganisms collected from the underground environment was designated as “H-RISE microorganism”. Specifically, deep underground water of diatomite (Shimizu et al., Geobiology, Vo4, pp203-213, 2006), deep underground water of coal formation (Shimizu et al., Geobiology, Vo5, pp 433-433, 2007), Oil and gas well production water (Shimizu et al., Bioscience, Biotechnology, and Biochemistry, Vo75, pp1835-1737, 2011) is used as a microorganism inoculum, and 0.1 mL each is 20 mL of JCM262 medium (http: //www.jcm .Riken.JP /) and inoculated. The culture vessel used was a 50 mL vial bottle sealed with a butyl rubber stopper and an aluminum seal. Using an anaerobic gas replacement device, the head space was almost completely replaced by repeating the decompression and pressurization (200 kPa) five times with a H ₂ —CO ₂ mixed gas having a volume ratio of 4: 1. These were cultured for 35 days in a constant temperature bath at 30 ° C. and 37 ° C., and each culture solution was mixed in an equivalent amount, and then centrifuged at 2,000 × g, 4 ° C. for 20 minutes to remove the culture supernatant. The microbial cell part which is a precipitate was designated as H-RISE microorganism. The H-RISE microorganism is maintained by subculturing each of the above culture solutions under the same conditions.

[2-2] Analysis of H-RISE microorganisms First, among the H-RISE microorganisms, coal-derived microorganisms and unsterilized coal-derived microorganisms were analyzed. Specifically, after DNA is extracted in bulk using PowerSoil DNA Isolation Kit (MO BIO), the composition of the microbial community structure in the bulk DNA is expressed by the following PCR method (Touch Down method). It was determined by the next generation sequencing method.

  Using the Genome Sequencer FLX system (GS FLX +; Roche Diagnostics), a library was prepared from physically fragmented DNA and amplified by emulsion PCR. The analysis was performed by analyzing a sequence of about 500 to 700 bp at a time by the pyrosequencing method. The high-speed sequencing of PCR products was outsourced to Takara Bio Inc. Dragon Genomics Center.

(A) used primer set;
primer A: 5′-CGT ATC GCC TCC CTC GCG CCA TCA G-3 ′ (SEQ ID NO: 1) added with tag sequence and rRNA forward primer primer B: 5′-CTA TGC GCC TTG CCG CC 3 '(SEQ ID NO: 2) added with rRNA reverse primer

(B) forward primer and reverse primer when the subject is an archaea;
A519-539F: 5′-CAG CCG CCG CGG TAA HAC CRC-3 ′ (SEQ ID NO: 3)
A947R: 5′-TCC AAT TRA RCC GCA SGC-3 ′ (SEQ ID NO: 4)

(C) forward primer and reverse primer when the subject is a bacterium;
B515-532F: 5′-GTG CCA GCA GCC GCG GTA-3 ′ (SEQ ID NO: 5)
B969R: 5′-GTA AGG TTC YTC GCG T-3 ′ (SEQ ID NO: 6)

(D) PCR method conditions After one cycle of 7 minutes at 94 ° C., 1 minute at 95 ° C., 1 minute at 65-56 ° C. (so that the annealing temperature is lowered by 1 ° C. per cycle) Setting) and 10 cycles of 2 minutes at 72 ° C, followed by 20 cycles of 94 ° C for 1 minute, 55 ° C for 1 minute, and 72 ° C for 2 minutes, followed by 72 ° C for 10 minutes The elongation reaction was performed.

[2-3] H-RISE Microorganisms Identified at the Genus Level As described above, the H-RISE microorganisms identified at the genus level from the results of Example 2 [2-2] are as follows.
Archaea;
Methanosarcina, Methanosalsum, Thermicoccus, Methanoculus, Methanocorpusculum, Methanofollis, Methanobacterium, Thermoplasma,
Eubacteria;
[Firmicutes Gate] Acetobacterium, Alkalibacter, Alkaliphilus, Anaerosporobacter, Anaerotruncus, Anaerofilum, Anaerovorax, Bacillus, Blautia, Caldanaerobius, Caloramator, Clostridium, Christensenella, Dehalobacter, Dehalobacterium, Desulfotomaculum, Eubacterium, Erysipelothrix, Faecalibacterium, Flavonifractor, Geosporobacter, Desulfonispora, Gracilibacter, Hy rogenoanaerobacterium, Lutispora, Megasphaera, Mogibacterium, Moorella, Natronincola, Oscillibacter, Parasporobacterium, Papillibacter, Pelotomaculum, Pelospora, Peptoniphilus, Pseudoflavonifractor, Robinsoniella, Ruminococcus, Sedimentibacter, Soehngenia, Staphylococcus, Syntrophomonas, Tepidanaerobacter, Tissierella, Thermoanaerobacterium, Trichococc s,
[Bacteroidetes Gate] Alkaliflexus, Anaerohabdus, Bacteroides, Chryseobacterium, Meniscus, Palladibacter, Solitaire,
[Spirochaetes Gate] Spirochaeta, Sphaerochaeta,
[Actinobacteria Gate] Actinotalea, Atopobium, Cellulomonas, Conexibacter, Dietzia, Oryziumus, Rubrobacter, Streptomyces,
[Tenercutetes Gate] Acholplasma, Spiroplasma, Spiroplasma,
[Nitrospirae Gate] Leptospirillum,
[Dictylomi Gate] Dictyoglomus,
[Ruminobacillus gate] Ruminobacillus,
[Proteobacteria Gate] Acidithiobacillus, Acinetobacter, Alishewanella, Desulfomicrobium, Desulfuromonas, Desulfonatronum, Desulfovibrio, Geobacter, Halomonas, Hydrogenophaga, Pelobacter, Perlucidibaca, Pseudomonas, Serratia, Shewanella, Thiomicrospira

(3) Culture of H-RISE Microorganism The above-mentioned H-RISE microorganism identified at the genus level was cultured in a JCM262 medium and used as an inoculum source. The inoculum is centrifuged at 20,000 × g and 4 ° C. for 20 minutes, and after removing the supernatant completely, 1 mL of basal medium described later is added, and the microorganism is reconstituted by flushing with a pipette tip with a filter. The suspension was prepared in a 100 mL vial and then inoculated into the reaction solution described below. Using an anaerobic gas replacement device, the head space was almost completely replaced by repeating the decompression and pressurization (200 kPa) five times with a H ₂ —CO ₂ mixed gas having a volume ratio of 4: 1. These were cultured in a 30 ° C. and 37 ° C. thermostat for 35 days in a 30 ° C. and 37 ° C. thermostat.

The basal medium was an inorganic salt medium (Synthetic Low Salts; SL medium). The content was as follows, and it was adjusted to 1 L using SL-10 which is a trace element solution. Trace vitalamines were not added.
NH ₄ Cl 0.5g
MgCl ₂ · _{6H 2} O 0.5g
CaCl ₂ · 2H ₂ O 0.14 g
K ₂ HPO ₄ 0.14 g
KCl 0.1g
NaCl 0.6g
Fe (NH ₄ ) ₂ (SO ₄ ) ₂ · 6H ₂ O 0.002 g
NaHCO ₃ 2.5 g

(4) Preparation of reaction solution of lignite and hydrogen peroxide solution 50 g of lignite powder prepared in Example 2 (1) and hydrogen peroxide having a concentration of 1% (v / v) or 3% (v / v) 500 mL of the solution was placed in a 1 L pressure-resistant glass bottle and allowed to react under stirring at 30 ° C. with a magnetic stirrer for 6 days. Thereafter, the mixture was centrifuged at 17,700 × g for 40 minutes at 4 ° C., and the supernatant was decanted into a glass beaker to adjust to pH 7.

  The pH of the reaction solution of 1% (v / v) hydrogen peroxide and that of 3% (v / v) hydrogen peroxide are 4.05 and 2.80, respectively, and 5N NaOH is 0.45 mL each. 4 mL was added to adjust the pH of each reaction solution to 7, and then centrifuged again at 17,700 × g for 40 minutes at 4 ° C. to collect the clarified supernatant.

(5) Production of methane by inoculating microorganisms into reaction solution Reaction of reaction solution of 1% (v / v) hydrogen peroxide with concentration of 3% (v / v) hydrogen peroxide prepared in Example (4) The solution was used as a substrate, and 50 mL each was dispensed into a glass vial with a 100 mL butyl stopper and an aluminum cap. After adding 5 g of brown coal powder and the cultured H-RISE microorganism of Example 2 (2), Sealed with an autoclave sterilized aluminum seal, and an anaerobic gas replacement device is used to repeat the depressurization and pressurization 5 times with an N ₂ -CO ₂ mixed gas with a volume ratio of 4: 1. Replaced with The culture was performed at 30 ° C. as it was, and the methane concentration in the head space was measured at intervals of 7 days. As a comparative control, 1 mM acetic acid or 4 mM acetic acid was used in place of a reaction solution of 1% (v / v) hydrogen peroxide and a reaction solution of 3% (v / v) hydrogen peroxide. FIG. 12 is a graph showing the amount of methane produced together with the number of days of culture when a H-RISE microorganism is added to a reaction solution of 1% (v / v) hydrogen peroxide or 1 mM acetic acid as a substrate. FIG. 13 is a graph showing the amount of methane produced together with the number of culture days when H-RISE microorganisms were added to a reaction solution of 3% (v / v) hydrogen peroxide or 4 mM acetic acid as a substrate.

  As shown in FIG. 12 and FIG. 13, when the H-RISE microorganism is used as the microorganism inoculation source, the amount of methane produced is greater when the reaction solution of hydrogen peroxide is used as a substrate than when acetic acid is used as a substrate. It became clear that there were many.

  From the above results, it is clear that in a closed space where oxygen is blocked, methane can be produced using microorganisms after reacting coal and / or diatomite with a hydrogen peroxide solution to produce a carbon compound. Became.

<Example 3> Effect of reducing agent on methane production

  Effect of adding a reducing agent on the production of methane using microorganisms after producing carbon compounds by reacting coal and / or diatomite with hydrogen peroxide solution in a closed space where oxygen is blocked It was investigated.

50 mL of the acetic acid produced in Example 1 (1) as a substrate was divided into 9 glass vials with 100 mL butyl stoppers and aluminum caps, respectively, cysteine or sodium sulfide as a reducing agent, and Example 2 as a microorganism inoculum. The H-RISE microorganism of (2), the H-RISE microorganism and diatomite (diatomaceous earth) of Example 2 (2), or the H-RISE microorganism and lignite of Example 2 (2) were combined as follows.
(A) No reducing agent + H-RISE microorganism (B) Reducing agent (cysteine) + H-RISE microorganism (C) Reducing agent (sodium sulfide) + H-RISE microorganism (D) No reducing agent + H-RISE microorganism + diatomite (diatomaceous earth) )
(E) Reducing agent (cysteine) + H-RISE microorganism + diatomite (diatomaceous earth)
(F) Reducing agent (sodium sulfide) + H-RISE microorganism + diatomite (diatomaceous earth)
(G) No reducing agent + H-RISE microorganism + brown coal (H) reducing agent (cysteine) + H-RISE microorganism + brown coal (I) reducing agent (sodium sulfide) + H-RISE microorganism + brown coal

The concentration of acetic acid was 10 mM, the final concentrations of cysteine and sodium sulfide as reducing agents were 20 mg / L, and the addition amounts of diatomite (diatomaceous earth) and lignite were 5 g / 50 mL. Diatomite used is the rock mass collected from the JAEA URL 250m underground tunnel in April 2011, and lignite is taken from the riverbed outcrop of No. 223 in the Teshio Forest on June 23, 2011. did. These rock samples were vacuum packed immediately after collection and stored at −20 ° C. until used for experiments. The rock sample was pulverized to 0.5 mm or less in an anaerobic chamber immediately before the experiment with an autoclave-sterilized stainless steel mortar or chisel. If rocks are not used as a source of microorganism inoculation, add 5 g of a rock sample to a 100 mL vial in an anaerobic chamber, seal with a butyl rubber stopper and an aluminum seal, and then sterilize at 121 ° C for 1 hour using an autoclave. I went twice. Until now, this sterilization method has never caused the growth of microorganisms, so it can be considered that sterilization has been completed. Nine vials are sealed with an autoclave-sterilized aluminum seal, and the pressure reduction and pressurization are repeated 5 times with an N ₂ -CO ₂ mixed gas with a volume ratio of 4: 1 using an anaerobic gas displacement device. Almost completely replaced the headspace. The culture was performed at 30 ° C. as it was, and the methane concentration in the head space was measured at intervals of 7 days. The results for (A) to (C) are shown in FIG. 14, the results for (D) to (F) are shown in FIG. 15, and the results for (G) to (I) are shown in FIG.

  As shown in FIGS. 14 to 16, when sodium sulfide is added as a reducing agent, the H-RISE microorganism and diatomite (diatomaceous earth) on the 21st day from the start of the experiment when the microorganism inoculation source is H-RISE microorganism In the case of the above, on the 28th day from the start of the experiment, and in the case of the H-RISE microorganism and lignite, the methanogenic reaction generally reached a plateau on the 21st day from the start of the experiment. In addition, when cysteine is added as a reducing agent, 42 days from the start of the experiment when the microorganism inoculation source is the H-RISE microorganism, 35 days from the start of the experiment when the H-RISE microorganism and diatomite (diatomite) are used. In the case of using eyes, H-RISE microorganisms and lignite, the methanogenic reaction generally reached a plateau on the 21st day from the start of the experiment. On the other hand, when no reducing agent was added, the methanogenic reaction generally reached a plateau on the 28th day from the start of the experiment only when the microorganism inoculation source was H-RISE microorganisms and lignite.

  From the above results, it is better to inoculate microorganisms by adding a reducing agent after reacting coal and / or diatomite with a hydrogen peroxide solution to produce a carbon compound in a closed space where oxygen is blocked. It became clear that the production rate of methane was improved compared to the case where no reducing agent was added.

<Example 4> Production of methane gas in the strata Soya 夾 coal formation (Neotertiary), spring mining coal formation (Paleogene), Biei formation (Paleogene), voice formation (Neotertiology) Drill one or more wells from the ground of each layer toward the formation containing coal and / or diatomite, and if necessary, create cracks around one or more wells obtained by drilling .

  A hydrogen peroxide solution is injected from one or more wells obtained by drilling and reacting coal and / or diatomite contained in the formation with hydrogen peroxide to generate carbon compounds and create spaces. The microorganisms that produce methane using the carbon compound produced from one or more wells obtained by drilling as a substrate are added, or together with the microorganism that produces methane using the carbon compound as a substrate or the carbon compound as a substrate In addition to microorganisms that generate methane, methane can be generated by introducing or inducing at least one of unsterilized coal and diatomite.

  In addition, coal and / or diatoms from the ground of each layer of the Soya Pass Coal Formation (Neogene), Spring Mining Coal Formation (Paleogene), Biei Formation (Paleogene), and Voice Formation (Neotertiary) When one or more wells are drilled toward the formation containing rocks, the hydraulic fracturing method is used to cause cracks around one or more wells obtained by drilling simultaneously with the creation. be able to. In addition, in order to accelerate the production rate of methane, hydrogen peroxide solution is injected from one or more wells obtained by drilling, and coal and / or diatomite contained in the formation and hydrogen peroxide are injected. After making it react and producing | generating a carbon compound and producing | generating space, a reducing agent can be inject | poured. Furthermore, a hydrogen peroxide solution is injected from one or more wells obtained by drilling, and coal and / or diatomite contained in the formation is reacted with hydrogen peroxide to generate carbon compounds and space. After the formation of, the basic solution is injected to neutralize the time required for methane production.

Claims (4)

A method for producing methane gas in a formation from coal and / or diatomite contained in the formation,
A process of drilling from the ground toward the formation containing coal and / or diatomite;
A step of causing a crack around the one or more wells obtained by the well sinking, well drilling,
A hydrogen peroxide solution is injected from one or two or more wells obtained by the wells, and the carbon and / or diatomite contained in the formation is reacted with hydrogen peroxide to generate a carbon compound and the space. A step of generating,
After the step of generating the carbon compound and generating the space, injecting a reducing agent from one or more wells obtained by the well;
The step of introducing a microorganism that produces methane using the produced carbon compound as a substrate from one or two or more wells obtained by the drilling, and the production from the coal and / or diatomite remaining after the reaction. And a method of inducing a microorganism that produces methane using a carbon compound as a substrate. The method according to claim 1 , further comprising the step of injecting a basic solution from one or more wells obtained by the drilling. A step of well sinking, well drilling toward the ground into the formation containing coal and / or diatomite is a step of well sinking, well drilling toward the ground into the formation containing coal and / or diatomite using hydraulic fracturing, according to claim 1 or 2 the method according to.   The method according to any one of claims 1 to 3, wherein the reducing agent is cysteine or sodium sulfide.

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