Method for underground in-situ hydrogen production by utilizing exogenous functional microorganisms and application

Abstract

The invention discloses a method for underground in-situ hydrogen production by utilizing exogenous functional microorganisms and application. The slow release system containing the exogenous functional microorganisms is injected into a target oil and gas reservoir for dark fermentation, and underground in-situ hydrogen production is carried out. An exogenous functional microbial strain and a carrier are prepared into a slow-release system, so that the slow-release system can enter the deep position of an oil-gas reservoir along with injected water and then is slowly released, and the situation that the slow-release system is greatly enriched near a well is avoided. Meanwhile, the slow-release system utilizes the carrier immobilized microorganisms, has the advantages of being easy in biological concentration control, high in poison resistance, small in strain loss and the like, and is beneficial for exogenous functional microorganisms to play roles, so that the hydrogen production effect of the microorganisms is effectively played.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas field exploitation, and further to a method and application of underground in-situ hydrogen production using exogenous functional microorganisms. Background Art

[0002] Hydrogen energy is known as the "ultimate energy" for its clean and environmentally friendly, high efficiency, wide source, and energy storage. It is the best choice to replace mineral energy in the future and can effectively solve the problems of renewable energy consumption, global fossil energy crisis, global warming and environmental pollution. However, hydrogen is still mainly derived from the combustion of fossil fuels. To achieve the goal of green and low-carbon energy transformation, zero-emission hydrogen production methods need to be further developed and upgraded.

[0003] Existing research has focused on using oil and gas reservoirs for underground in-situ hydrogen production. The relevant technology mainly includes the following steps: injecting a catalyst into the ground, raising the temperature of the oil and gas reservoir to a temperature that can cause hydrocarbons to be oxidized, hydrothermally cracked or reformed into hydrogen by injecting water vapor, injecting air and igniting downhole, and finally achieving the purpose of underground in-situ hydrogen production. Underground in-situ hydrogen production can avoid the large-scale ground facilities required for ground hydrogen production, and can also achieve simultaneous and on-site storage of carbon dioxide. However, the temperature required for underground heating to produce hydrogen is high, the heating process is difficult, and additional energy is consumed. Hydrogen-producing functional microorganisms provide a new idea that can achieve low-temperature and low-energy underground in-situ hydrogen production.

[0004] Many microorganisms can produce biohydrogen through different reactions and metabolic pathways. For example, hydrogen can be produced using light energy or chemical energy in organic compounds (such as sugars). Among them, the most promising approach is the conversion of sugars or similar substrates by fermentative microorganisms to produce hydrogen, which is usually called "dark fermentation." Dark fermentation occurs under anaerobic conditions without light. Anaerobic microorganisms convert organic compounds into biohydrogen and produce various organic acids or alcohols as byproducts. Dark fermentation has a high hydrogen release rate. Dark fermentation produces hydrogen quickly and efficiently, and is more suitable for application in underground environments.

[0005] However, the inventors of the present invention have found through research that in the prior art, microorganisms and nutrients are directly injected into the ground, which easily leads to a large number of microorganisms enriched near the wellbore and cannot be effectively injected into the deep oil and gas reservoir, resulting in poor hydrogen production effect. Therefore, it is necessary to develop a new method with good hydrogen production effect. Summary of the invention

[0006] In order to solve the problems in the prior art, the present invention proposes a method and application of underground in-situ hydrogen production using exogenous functional microorganisms. The present invention prepares the exogenous functional microbial strains and carriers into a slow-release system, so that they can be slowly released after entering the deep of the oil and gas reservoir with the injected water, avoiding their large-scale enrichment near the well. At the same time, the slow-release system of the present invention uses the advantages of carrier-immobilized microorganisms, such as easy control of biological concentration, strong resistance to toxicity, and less bacterial loss, which is beneficial to the exogenous functional microorganisms to play a role, thereby effectively exerting the hydrogen production effect of the microorganisms.

[0007] One of the purposes of the present invention is to provide a method for underground in-situ hydrogen production using exogenous functional microorganisms, comprising the following steps:

[0008] A slow-release system containing exogenous functional microorganisms is injected into the target oil and gas reservoir to perform dark fermentation and underground in-situ hydrogen production.

[0009] The present invention first injects exogenous functional microorganisms into the injection wells of the oil and gas reservoir. The exogenous functional microorganisms are prepared as a slow-release system so that they can be slowly released after entering the deep of the oil and gas reservoir with the injected water to avoid their large-scale enrichment near the well. Then, nutrients are injected to activate the functional microorganisms, so that they can multiply rapidly and efficiently produce hydrogen. Through the above process, the lack of functional microorganisms in the oil and gas reservoir can be effectively supplemented, the population structure of hydrogen-producing microorganisms can be improved, the number and metabolic activity of functional microorganisms can be increased, and the underground in-situ microbial hydrogen production effect can be improved.

[0010] In the method for underground in-situ hydrogen production using exogenous functional microorganisms of the present invention, preferably, the following steps are included:

[0011] (1) Conduct macro-environmental survey of oil and gas reservoirs to determine the target oil and gas reservoirs for hydrogen production;

[0012] (2) Conduct micro-environmental surveys on the target oil and gas reservoirs for hydrogen production to obtain information on the endogenous microbial community composition of the target oil and gas reservoirs;

[0013] (3) Selecting exogenous functional microorganisms that match endogenous microorganisms and performing specific domestication;

[0014] (4) preparing a sustained-release system containing the exogenous functional microorganisms specifically domesticated in step (3);

[0015] (5) transporting the slow-release system to a target layer of a target oil and gas reservoir;

[0016] (6) activating and culturing underground exogenous functional microorganisms in situ to perform dark fermentation;

[0017] (7) Hydrogen acquisition.

[0018] The method of the present invention is aimed at oil and gas resources that cannot be produced under existing economic and technical conditions, and can be used to simultaneously implement the reuse of surplus oil and gas resources to produce hydrogen on a large scale under low temperature conditions. Since the method can produce hydrogen and also store carbon dioxide on-site, it effectively solves the problem of high carbon emissions from existing hydrogen production technologies.

[0019] In the method for underground in-situ hydrogen production using exogenous functional microorganisms of the present invention, preferably, in step (1),

[0020] Investigate the geological and physical characteristics of the oil and gas reservoirs, preferably investigate the temperature, porosity, pressure, permeability, degree of recovery, remaining oil distribution, oil product characteristics, and formation water salinity of the oil and gas reservoirs;

[0021] Further preferably, the temperature of the target oil and gas reservoir is less than 90°C, the formation water salinity is less than 50000 mg / L, and the permeability is ≥10×10 -3 μm 2 ;

[0022] Still more preferably, in the target oil and gas reservoir,

[0023] 20℃≤Oil and gas reservoir temperature≤70℃; and / or,

[0024] 500mg / L≤ formation water mineralization≤2000mg / L; and / or,

[0025] 10×10 -3 μm 2 ≤Permeability≤1000×10 -3 μm 2 .

[0026] In the method for underground in-situ hydrogen production using exogenous functional microorganisms of the present invention, preferably,

[0027] In step (2),

[0028] Use at least one of 16SrRNA gene sequencing and metagenomic sequencing to conduct a micro-environmental survey of the target oil and gas reservoir.

[0029] In the method for underground in-situ hydrogen production using exogenous functional microorganisms of the present invention, preferably,

[0030] In step (3),

[0031] The exogenous functional microbial agent is obtained by selecting suitable functional strains and mixing them for cultivation based on the results of the macro- and micro-environmental investigation of the oil and gas reservoir; the selected exogenous functional microbial strains are the exogenous functional microbial strains that have the best hydrogen production effect with the endogenous microorganisms of the target oil and gas reservoir and / or are least affected by the endogenous microorganisms; and / or,

[0032] Add growth limiting factors to further specifically domesticate the selected exogenous functional microorganisms to better adapt to the target oil and gas reservoirs;

[0033] Preferably, the exogenous microbial strains are mixed and cultured with the endogenous microorganisms, and the exogenous functional microbial strains with the best hydrogen production effect in coordination with the endogenous microorganisms of the target oil and gas reservoir are screened out based on the total hydrogen production; or, the exogenous microbial strains are mixed and cultured with the endogenous microorganisms, and the exogenous functional microbial strains that are least affected by the endogenous microorganisms are screened out based on the survival time of the exogenous functional microbial strains; among them, the exogenous functional microbial strains with the longest survival time are the exogenous functional microbial strains that are least affected by the endogenous microorganisms, and the exogenous functional microbial strains with the longest survival time are the exogenous functional microbial strains that are least affected by the endogenous microorganisms;

[0034] In the present invention, the total hydrogen production is calculated by the time that hydrogen can be produced (that is, the survival time of the functional microorganisms)*the hydrogen production per unit time;

[0035] Still more preferably,

[0036] The exogenous functional microbial strain is selected from functional microorganisms for dark fermentation hydrogen production; preferably at least one selected from Clostridium, Desulfovibrio, Escherichia, Butyric Bacillus, Citrobacter, Klebsiella, Enterobacter, Acetobacter, Methanococcus; and / or,

[0037] Growth limiting factors are added to further specifically domesticate the selected exogenous functional microorganisms to make them more suitable for the target oil and gas reservoirs. Preferably, the growth limiting factors include but are not limited to at least one of oligotrophy, high salt, high temperature, and heavy metals that simulate the growth environment of the target oil and gas reservoirs.

[0038] After specific domestication, a specifically domesticated exogenous functional microbial agent can be obtained. The solution in the agent may be a nutrient, such as LB culture medium, or it may be a solution such as PBS or saline that is only used to adjust the osmotic pressure, or a substance such as glycerol that maintains the activity of microorganisms.

[0039] In the method for underground in-situ hydrogen production using exogenous functional microorganisms of the present invention, preferably,

[0040] In step (4),

[0041] The sustained-release system comprises a carrier, a specifically domesticated exogenous functional microorganism adsorbed on the carrier, and a background solution, wherein the carrier and the specifically domesticated exogenous functional microorganism adsorbed on the carrier are dispersed in the background solution;

[0042] More preferably,

[0043] The carrier has the characteristics of long-distance migration in oil and gas reservoirs, not easily decomposed by microorganisms, non-toxic, and acid and alkali resistant. Preferably, the carrier is selected from a basic carrier or a modified carrier in which at least one modified substance selected from nano fluorescent substances and magnetic particles is added to the basic carrier; and / or,

[0044] The background solution is a solution for culturing specific domesticated exogenous functional microorganisms; and / or,

[0045] The concentration of the carrier in the background solution ranges from 200 mg / L to 1500 mg / L;

[0046] Still further preferably, the base carrier is selected from at least one of a natural inorganic material carrier, a synthetic inorganic material carrier, a natural organic material carrier, and a synthetic organic material carrier.

[0047] In the slow-release system of the present invention, the background solution is preferably a liquid that is non-toxic to microorganisms and underground environment and has good dispersion performance on the carrier. The background solution is a substance commonly used to cultivate and propagate strains, and is an existing conventional culture solution.

[0048] In the method for underground in-situ hydrogen production using exogenous functional microorganisms of the present invention, preferably,

[0049] In step (4),

[0050] The natural inorganic material carrier is selected from at least one of sand, zeolite, vermiculite and diatomaceous earth; and / or,

[0051] The synthetic inorganic material carrier is selected from at least one of activated carbon, porous ceramic biochar, porous glass, and silica gel; and / or,

[0052] The natural organic material carrier is selected from at least one of agar, carrageenan, alginate, cellulose and gelatin; and / or,

[0053] The synthetic organic material carrier is selected from at least one of polyurethane foam, ion exchange resin (such as styrene, acrylic, phenolic and epoxy ion exchange resin), polyvinyl alcohol, polypropylene (preferably polypropylene fiber), and polyacrylamide; and / or,

[0054] The nano fluorescent material in the modified carrier is selected from at least one of polymer fluorescent nano materials, carbon-based nano fluorescent materials, and silicon-based nano fluorescent materials; preferably, the nano fluorescent material is selected from polymer fluorescent nano microspheres, carbon-based nano fluorescent particles, and silicon-based nano fluorescent particles; further preferably, at least one of fluorescent quantum dots; and / or,

[0055] The magnetic particles in the modified carrier are selected from at least one of neodymium iron boron magnetic powder and ferroferric oxide particles;

[0056] In the present invention, the carrier is further modified / modified with fluorescent substances or magnetic particles during the preparation process to obtain a modified carrier, so that the carrier can not only be used as a place to load microorganisms, but also can simultaneously realize functions such as tracing and remote control. The modified carrier uses existing materials, which can be directly purchased or prepared according to existing methods, such as surface oxidation modification, surface reduction modification, metal loading modification, etc.

[0057] In the present invention, the preparation method of the sustained-release system mainly includes fixing the exogenous functional microbial strains and the above-screened exogenous functional microbial agents on a carrier through physical adsorption and charge effect to prepare a sustained-release agent system, so that the microorganisms are highly densely enriched in the pores or surface of the carrier and maintain biological activity, laying the foundation for their rapid reproduction under suitable conditions. The method of loading the microbial agent on the carrier is mainly to fix the microbial strains on the carrier by adsorption, embedding, cross-linking, covalent bonding and the like. The preparation method of the sustained-release system in the present invention also adopts the loading method commonly used in the prior art. Those skilled in the art can select a suitable loading method according to the microbial strains and carrier characteristics.

[0058] In the method for underground in-situ hydrogen production using exogenous functional microorganisms of the present invention, preferably, in step (5),

[0059] Using the oil and gas reservoir water injection well, the exogenous functional microbial agent slow-release system is transported to the target layer of the target oil and gas reservoir;

[0060] Preferably, the exogenous functional microbial agent slow-release system is transported to the target layer of the target oil and gas reservoir by using a water injection well in the oil and gas reservoir in at least one of a slug-type and multi-round injection method; and / or,

[0061] The injection amount of the exogenous functional microbial agent sustained-release system is 0.1-0.3 PV (pore volume), preferably 0.1-0.2 PV;

[0062] The injection speed of the exogenous functional microbial agent slow-release system is 5 to 20 m 3 / h, preferably 8 to 15m 3 / h.

[0063] In the present invention, PV is the pore volume of the target oil and gas reservoir; the unit is m 3 For example, 0.1-0.3PV refers to 0.1-0.3 times the pore volume.

[0064] In the present invention, the microbial agent is transported to the target formation by using the water injection well of the oil and gas reservoir. According to different oil and gas reservoir conditions and oil product characteristics, the basic technical route of combining well injection, multi-well joint production, throughput and displacement is adopted in the process, with slug-type and multi-round injection as the basic technical means.

[0065] In the method for underground in-situ hydrogen production using exogenous functional microorganisms of the present invention, preferably, in step (6),

[0066] Injecting nutrients into the target formation to activate and cultivate exogenous functional microorganisms in situ underground to achieve rapid reproduction of exogenous functional microbial strains; performing dark fermentation; and / or,

[0067] The injection volume of nutrients is 0.1-0.3 PV, preferably 0.1-0.2 PV, and the injection speed is 5-15 m 3 / h, preferably 5 to 10 m 3 / h;

[0068] In the present invention, PV is the pore volume of the target oil and gas reservoir; the unit is m 3 For example, 0.1-0.3PV refers to 0.1-0.3 times the pore volume;

[0069] Preferably,

[0070] The nutrient is selected from at least one of glucose, acetic acid, propionic acid, ethanol, propanol and a long-chain organic matter with a carbon number greater than 3; preferably, the long-chain organic matter is selected from at least one of cellulose and lignin; in the present invention, the long-chain substance is a long-chain organic matter that is not easily consumed by microorganisms, in order to achieve "not easily consumed by microorganisms in the near-wellbore area".

[0071] Further preferably, the nutrients also include an acid-base regulator;

[0072] Still more preferably, the acid-base regulator is selected from at least one of hydrochloric acid and sodium hydroxide.

[0073] In the present invention, the underground environment is adjusted by supplementing nutrients. The injection of nutrients first solves the problem of oligotrophy in the underground, and secondly, the acidity and alkalinity of the underground can be adjusted through the process of supplementing nutrients. Hydrochloric acid and sodium hydroxide are used to adjust the acidity and alkalinity of the injected nutrients, thereby adjusting the underground acidity and alkalinity environment, and adjusting the underground environment to a condition suitable for the growth of microorganisms, so that they can reproduce rapidly.

[0074] In the method for underground in-situ hydrogen production using exogenous functional microorganisms of the present invention, preferably, in step (7),

[0075] Near the outlet of the production well, a semi-permeable membrane that only allows hydrogen to pass through is installed to achieve on-site separation of the produced hydrogen and directly seal the carbon dioxide in the formation;

[0076] Preferably, the semipermeable membrane is a polymer membrane, preferably at least one of a polysulfone membrane, a dimethylsiloxane membrane or a polyimide membrane.

[0077] A second object of the present invention is to provide the application of the method for underground in-situ hydrogen production using exogenous functional microorganisms as described in any one of the objects of the present invention in oil and gas field exploitation.

[0078] The present invention provides an underground in-situ hydrogen production method using exogenous functional microorganisms. This method targets oil and gas resources that cannot be produced under existing economic and technical conditions, and uses exogenous functional microorganisms and carriers to prepare a bacterial agent slow-release system that can be transported over long distances in oil and gas reservoirs. The system reaches the destination layer through an injection well, injects nutrients to activate functional microorganisms to achieve "dark fermentation" hydrogen production, and finally collects the output hydrogen through production wells. This technology can synchronously implement the reuse of residual oil and gas resources for hydrogen production on a large scale under low temperature conditions. It can not only utilize existing pipelines to avoid drilling and new pipelines, but also save the cost of building large-scale hydrogen production equipment on the ground. It can store carbon dioxide on site while producing hydrogen, and can also effectively solve the high carbon emission problem of existing hydrogen production technology. The microbial technology of the present invention avoids the disadvantages of existing underground in-situ hydrogen production technology that requires energy-consuming heating, and improves the efficiency of hydrogen production through effective microbial injection means.

[0079] The endpoints and any values ​​of the scope disclosed in the present invention are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, the endpoint values ​​of each scope, the endpoint values ​​of each scope and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be regarded as specifically disclosed in this article.

[0080] Compared with the prior art, the present invention has at least the following advantages:

[0081] (1) The hydrogen production method of the present invention can make full use of the exhausted, abandoned, and unexploitable oil and gas resources and existing pipeline networks, saving drilling and pipeline network construction investment and increasing economic benefits;

[0082] (2) The hydrogen production method of the present invention uses the flow channel composed of porous media in the formation as the hydrogen production site, eliminating the need to build a complex and large-scale hydrogen production device on the ground;

[0083] (3) The present invention utilizes exogenous functional microorganisms to produce hydrogen underground in situ, which can be directly implemented at the temperature of the oil and gas reservoir without the need for heating or other temperature control operations;

[0084] (4) The present invention produces hydrogen while sealing carbon dioxide, thereby reducing carbon emissions and increasing formation pressure.

[0085] (5) With the help of the slow-release system, the exogenous functional microorganisms of the present invention can enter deeper into the oil layer to exert their effects, so as to prevent the microorganisms from being adsorbed on the bottom layer near the injection well and failing to reach the target layer; secondly, the use of a slow-release system to immobilize microorganisms has the advantages of easy control of biological concentration, strong resistance to toxicity, and less loss of bacteria, which is beneficial to the functional microorganisms to exert their effects; finally, the carrier can become a medium for information exchange between the ground and the underground and for the ground to exert influence on the underground, such as tracing. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 It is a structural schematic diagram of the exogenous functional microbial agent sustained-release system;

[0087] Figure 2 Schematic diagram of the method of underground in situ hydrogen production using exogenous functional microorganisms.

[0088] Description of reference numerals:

[0089] Figure 1 In the invention, 1- sustained release system, 2- background solution, 3- exogenous functional microorganisms, and 4- carrier.

[0090] Figure 2 In the figure, A-injection well, B-production well, C-semipermeable membrane.

[0091] like Figure 1 As shown, the slow-release system 1 is composed of a background solution 2, exogenous functional microorganisms 3, and a carrier 4 to which the exogenous functional microorganisms are attached. The background solution 2 should be a liquid that is non-toxic to the microorganisms and the underground environment and has good dispersion performance on the carrier. The exogenous functional microorganisms 3 may include Clostridium, Desulfovibrio, Escherichia, Butyric Bacillus, Citrobacter, Klebsiella, Enterobacter, Acetobacter, Methanococcus, and other functional microorganisms that can produce hydrogen by dark fermentation. The carrier 4 should have the characteristics of being able to migrate over long distances in oil and gas reservoirs, not easily decomposed by microorganisms, non-toxic, acid and alkali resistant, etc., and can also be doped or selected with materials with special functions such as fluorescence, magnetism, etc. that can realize tracing, remote control, etc.

[0092] like Figure 2 As shown in the figure, try to select wells with casing suitable for corrosive media such as hydrogen sulfide (such as casing with steel grades of M65, L80, C90, C95, T95, etc.) as injection well A and production well B; if there is no suitable well in the target oil and gas field, the existing well can be transformed by in-situ anti-corrosion means (such as adding epoxy coating to the casing, etc.). The slow-release system containing exogenous functional microorganisms is injected into the target oil and gas reservoir through injection well A (the target oil and gas reservoir temperature should be less than 90℃, the formation water salinity should be less than 50000mg / L, and the permeability should be greater than 100×10 -3 μm 2) after being added, it is not only a slow-release source of microbial agents, but also can adsorb reaction substrates while attaching microorganisms to become a place for dark fermentation reactions. Nutrients used to activate exogenous functional microorganisms can be used as Figure 1 The background solution 2 (background solution 2 is a substance commonly used to cultivate and propagate strains) is injected into the oil and gas reservoir together with the exogenous functional microorganisms 3. It can also be injected after the exogenous functional microorganisms' slow-release system 1 is injected and when activation is required. The nutrients used to activate the exogenous functional microorganisms should, under the premise of meeting the growth requirements of the exogenous functional microorganisms, try to select substances that are slowly consumed by other microorganisms (such as long carbon chain substances containing high molecular weights) to avoid their metabolic depletion by endogenous microorganisms near the wellbore, thereby improving the effective utilization rate of nutrients by the exogenous functional microorganisms. The total number of culturable bacteria after activation should be >10 7 CFU / mL.

[0093] After hydrogen is produced by exogenous functional microorganisms, it will be produced from production well B through semipermeable membrane C. Other byproducts such as carbon dioxide cannot pass through semipermeable membrane C. In the process of separating hydrogen, greenhouse gases can be sealed on site. Semipermeable membrane C can be made of polymer membranes such as polysulfone, dimethylsiloxane or polyimide, which have a large permeation rate and high selective separation for hydrogen. DETAILED DESCRIPTION

[0094] The present invention is described in detail below in conjunction with specific drawings and embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0095] It should also be noted that the various specific technical features described in the following specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0096] In addition, the various embodiments of the present invention may be arbitrarily combined as long as they do not violate the concept of the present invention. The technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0097] The raw materials used in the examples and comparative examples, unless otherwise specified, are disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0098] Example 1

[0099] 1. Macro-environmental survey of oil and gas reservoirs. Investigate the geological and physical characteristics of oil and gas reservoirs and other environmental conditions, including reservoir temperature, porosity, pressure, permeability, recovery degree, remaining oil distribution, oil product characteristics, formation water salinity, etc. The survey found that the target oil and gas reservoir block: reservoir temperature 33 ° C, formation water salinity 4213 mg / L, permeability 1130 × 10 -3 μm 2 , pore volume 4.6×10 5 m 3 .

[0100] 2. Investigation of the micro-environment of oil and gas reservoirs: Based on 16SrRNA gene sequencing analysis, the main bacterial genera are Pseudomonas, Thermophilic Bacteria, and Desulfovibrio, and the archaea are mainly composed of methanogens, Methanobacteria, and Nitrite Bacteria.

[0101] 3. Preparation of exogenous functional microbial agents. According to the composition of the microbial community in the target oil and gas reservoir, select exogenous functional microorganisms such as Bacillus butyricum and Klebsiella that are least affected by endogenous microorganisms, and then culture and prepare the agent.

[0102] After determining the exogenous functional microorganisms, the selected microorganisms can be specifically domesticated using oligotrophic culture media that simulate the growth environment of the target oil and gas reservoir and other growth limiting factors. Specifically, 2 mL of bacterial liquid is added to the oligotrophic liquid culture medium (specific composition: beef extract: 1.00 g / L; peptone: 2.00 g / L; D-xylose: 2.00 g / L; glucose: 2.00 g / L; NaCl: 1.00 g / L; KH2PO4: 0.10 g / L; MgSO4·7H2O: 0.20 g / L), and cultured at 37°C and 180 rpm for 3 days, which is the first generation of domesticated bacterial agent. The second generation domestication is to take 2 mL of bacterial liquid in the first generation domestication system, inoculate it into a liquid culture medium with half the nutrient content (here, it means that the nutrients in the oligotrophic liquid culture medium in the first generation of bacterial agents are further reduced by half) and cultured, and then domesticated to the fifth generation.

[0103] 4. Preparation of a sustained-release bacterial agent system. A carrier is selected that can be transported over long distances in oil and gas reservoirs, is not easily decomposed by microorganisms, is non-toxic, and is resistant to acid and alkali. The carrier selected in this embodiment is a biomass-based iron-carbon composite material. The preparation method is to slowly add a FeCl3 solution to galacturonic acid, and continuously stir the reaction solution at room temperature until a yellow-brown gel system is obtained. The colloidal raw material is freeze-dried to obtain a biomass-based iron-carbon composite nanomaterial premix. Using a tubular furnace, the premix is ​​pyrolyzed and calcined in an inert gas (N2) atmosphere, and maintained for 0.5h after reaching 600°C to obtain a biomass-based iron-carbon composite material.

[0104] The above-screened and specifically domesticated exogenous functional microbial agent is fixed on the carrier through physical adsorption and charge effect. Specifically, the specifically domesticated exogenous functional microbial agent is inoculated into a liquid culture medium (i.e., background solution, specifically composed of: beef extract: 5.00 g / L; peptone: 10.00 g / L; D-xylose: 10.00 g / L; glucose: 10.00 g / L; NaCl: 5.00 g / L; KH2PO4: 0.50 g / L; MgSO4·7H2O: 1.00 g / L), and after expanding the culture to the logarithmic growth phase, the prepared biomass-based iron-carbon carrier is immersed in the above solution, and the concentration of the carrier in the background solution is 1000 mg / L. After continuous culture for 3 days, a sustained-release system of the agent is obtained, so that the microorganisms are highly densely enriched in the pores or surface of the carrier and maintain biological activity, thereby laying a foundation for their rapid reproduction under suitable conditions. The structure of the sustained-release system of the exogenous functional microbial agent of the present invention is as follows Figure 1 shown.

[0105] 5. Transport of microbial slow-release system. Use water injection wells in oil and gas reservoirs to transport the microbial slow-release system to the target formation. Figure 2 The specific injection process is to use a high-pressure pump truck to inject the bacterial agent slow-release system into the injection well A of the block, with an injection volume of 0.5×10 5 m 3 , injection speed is 8m 3 / h.

[0106] 6. In-situ activation and cultivation of exogenous functional microorganisms. Use the water injection wells in the waste oil and gas reservoirs to add nutrients required for microbial growth to the wells, adjust the well environment to the conditions suitable for microbial growth, and make them reproduce rapidly. Nutrient composition: glucose mass concentration of 0.5%, cellulose mass concentration of 0.3%, cassava powder mass concentration of 0.2%, potassium dihydrogen phosphate mass concentration of 0.03%, and the rest is water. The injection volume is 0.5×10 5 m 3 , injection speed is 5m 3 / h.

[0107] 7. Hydrogen acquisition. Near the outlet of production well B, a semipermeable membrane C (polysulfone polymer semipermeable membrane) that only allows hydrogen to pass through is installed to achieve on-site separation of the produced hydrogen and directly seal the carbon dioxide in the formation.

[0108] The above-mentioned method of underground in-situ hydrogen production using exogenous functional microorganisms can produce a total cumulative hydrogen output of 5×10 5 m 3 .

[0109] Example 2

[0110] It adopts a preparation method basically the same as that of Example 1, and performs underground in-situ hydrogen production in another injection well A' (which corresponds to production well B') in the same target oil and gas reservoir block as Example 1, and the difference is only in the carrier. The preparation method of the carrier includes: crushing and sieving bamboo charcoal for standby use. Take FeCl3·6H2O to prepare a 50mol / L aqueous solution. Add bamboo charcoal powder to the FeCl3·6H2O aqueous solution according to 100g / L, stir and mix well at a rate of 500r / min, soak and stir continuously for 30min, and then heat to 70℃ at a rate of 5℃ / min and maintain for 30min. Wash repeatedly with water until the filtrate is neutral, separate the solid particles and dry at 60℃. Finally, a bamboo charcoal-based carrier loaded with Fe3O4 magnetic nanoparticles is obtained.

[0111] The above-mentioned method of underground in-situ hydrogen production using exogenous functional microorganisms can produce a total cumulative hydrogen output of up to 6×10 5 m 3 .

[0112] Comparative Example 1

[0113] The method is basically the same as that in Example 1, and underground in-situ hydrogen production is carried out in another injection well A" (which corresponds to the production well B") different from that in Example 1 and Example 2 in the same target oil and gas reservoir block as Example 1. The only difference is that the comparative example 1 does not include step (4), and the domesticated exogenous functional microbial agent is directly injected into the target oil and gas reservoir to produce hydrogen by dark fermentation. The cumulative total hydrogen production can reach 2×10 5 m 3 .

[0114] From the results of Example 1 and Comparative Example 1, it can be seen that the effect of underground in-situ hydrogen production using exogenous functional microorganisms in the present invention is significantly better than the hydrogen production effect of the method of directly injecting exogenous functional microbial agents in the prior art.

[0115] In summary, the underground in-situ hydrogen production method using exogenous functional microorganisms provided by the present invention mainly consists of key steps such as oil and gas reservoir environmental investigation, exogenous functional microbial agent preparation, agent slow-release system preparation and transportation, exogenous functional microorganism underground in-situ activation and cultivation, hydrogen acquisition, etc. This method solves the problems of high carbon emissions of ground hydrogen production technology and high energy consumption of existing underground in-situ hydrogen production technology, and realizes low-temperature, large-scale, synchronous and efficient underground hydrogen production through the design of exogenous functional microbial injection mode.

[0116] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0117] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of a conflict, the definition in this specification shall prevail.

[0118] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0119] In the context of the present specification, any matters or items not mentioned are directly applicable to those known in the art without any changes except those explicitly stated.

Claims

1. A method for underground in-situ hydrogen production using exogenous functional microorganisms, comprising the following steps: A slow-release system containing exogenous functional microorganisms is injected into the target oil and gas reservoir to perform dark fermentation and underground in-situ hydrogen production.

2. The method for underground in-situ hydrogen production using exogenous functional microorganisms according to claim 1, characterized in that: The following steps are involved: (1) Conduct macro-environmental survey of oil and gas reservoirs to determine the target oil and gas reservoirs for hydrogen production; (2) Conduct micro-environmental surveys on the target oil and gas reservoirs for hydrogen production to obtain information on the endogenous microbial community composition of the target oil and gas reservoirs; (3) Selecting exogenous functional microorganisms that match endogenous microorganisms and performing specific domestication; (4) preparing a sustained-release system containing the exogenous functional microorganisms specifically domesticated in step (3); (5) transporting the slow-release system to a target layer of a target oil and gas reservoir; (6) activating and culturing underground exogenous functional microorganisms in situ to perform dark fermentation; (7) Hydrogen acquisition.

3. The method for underground in-situ hydrogen production using exogenous functional microorganisms according to claim 2, characterized in that: In step (1), Investigate the geological and physical characteristics of the oil and gas reservoirs, preferably investigate the temperature, porosity, pressure, permeability, degree of recovery, remaining oil distribution, oil product characteristics, and formation water salinity of the oil and gas reservoirs; Further preferably, the temperature of the target oil and gas reservoir is less than 90°C, the formation water salinity is less than 50000 mg / L, and the permeability is ≥10×10 -3 μm 2 ; Still more preferably, in the target oil and gas reservoir, 20℃≤Oil and gas reservoir temperature≤70℃; and / or, 500mg / L≤ formation water mineralization≤2000mg / L; and / or, 10×10 -3 μm 2 ≤Permeability≤1000×10 -3 μm 2 .

4. The method for underground in-situ hydrogen production using exogenous functional microorganisms according to claim 2, characterized in that: In step (2), Use at least one of 16SrRNA gene sequencing and metagenomic sequencing to conduct a micro-environmental survey of the target oil and gas reservoir.

5. The method for underground in-situ hydrogen production using exogenous functional microorganisms according to claim 2, characterized in that: In step (3), The selected exogenous functional microbial strain is the one that has the best hydrogen production effect with the endogenous microorganisms of the target oil and gas reservoir and / or is the exogenous functional microbial strain that is least affected by the endogenous microorganisms; and / or, Add growth limiting factors to further specifically domesticate the selected exogenous functional microorganisms to better adapt to the target oil and gas reservoirs; Preferably, Mix exogenous microbial strains with endogenous microorganisms and screen out the exogenous functional microbial strains with the best hydrogen production effect with the endogenous microorganisms in the target oil and gas reservoir based on the total hydrogen production; or Mix exogenous microbial strains with endogenous microorganisms and culture them, and screen out the exogenous functional microbial strains that are least affected by the endogenous microorganisms based on the survival time of the exogenous functional microbial strains; More preferably, The exogenous functional microbial strain is selected from at least one of Clostridium, Desulfovibrio, Escherichia, Butyric Bacillus, Citrobacter, Klebsiella, Enterobacter, Acetobacter, and Methanococcus; and / or, The growth limiting factor includes at least one of oligotrophic, high salt, high temperature and heavy metals to simulate the growth environment of the target oil and gas reservoir.

6. The method for underground in-situ hydrogen production using exogenous functional microorganisms according to claim 2, characterized in that: In step (4), The sustained-release system comprises a carrier, a specifically domesticated exogenous functional microorganism adsorbed on the carrier, and a background solution, wherein the carrier and the specifically domesticated exogenous functional microorganism adsorbed on the carrier are dispersed in the background solution; Preferably, The carrier is selected from a basic carrier or a modified carrier in which at least one modified substance selected from nano fluorescent substances and magnetic particles is added to the basic carrier; and / or, The background solution is a solution for culturing specific domesticated exogenous functional microorganisms; and / or, The concentration of the carrier in the background solution ranges from 200 mg / L to 1500 mg / L; More preferably, The base carrier is selected from at least one of a natural inorganic material carrier, a synthetic inorganic material carrier, a natural organic material carrier, and a synthetic organic material carrier.

7. The method for underground in-situ hydrogen production using exogenous functional microorganisms according to claim 6, characterized in that: In step (4), The natural inorganic material carrier is selected from at least one of sand, zeolite, vermiculite and diatomaceous earth; and / or, The synthetic inorganic material carrier is selected from at least one of activated carbon, porous ceramic biochar, porous glass, and silica gel; and / or, The natural organic material carrier is selected from at least one of agar, carrageenan, alginate, cellulose and gelatin; and / or, The synthetic organic material carrier is selected from at least one of polyurethane foam, ion exchange resin, polyvinyl alcohol, polypropylene and polyacrylamide; and / or, The nano fluorescent substance in the modified carrier is selected from at least one of polymer fluorescent nano substances, carbon-based nano fluorescent substances, and silicon-based nano fluorescent substances; and / or, The magnetic particles in the modified carrier are selected from at least one of neodymium iron boron magnetic powder and ferrosoferric oxide particles.

8. The method for underground in-situ hydrogen production using exogenous functional microorganisms according to claim 2, characterized in that: In step (5), Using the oil and gas reservoir water injection well, the exogenous functional microbial agent slow-release system is transported to the target layer of the target oil and gas reservoir; Preferably, the exogenous functional microbial agent slow-release system is transported to the target layer of the target oil and gas reservoir by using a water injection well in the oil and gas reservoir in at least one of a slug-type and multi-round injection method; and / or, The injection volume of the exogenous functional microbial agent slow-release system is 0.1-0.3 PV, preferably 0.1-0.2 PV; the PV is the pore volume of the target oil and gas reservoir; The injection speed of exogenous functional microbial agents is 5 to 20 m 3 / h, preferably 8 to 15m 3 / h.

9. The method for underground in-situ hydrogen production using exogenous functional microorganisms according to claim 2, characterized in that: In step (6), Inject nutrients into the target formation to activate and cultivate exogenous functional microbial agents underground in situ for dark fermentation; The injection volume of nutrients is 0.1-0.3 PV, preferably 0.1-0.2 PV, and the injection speed is 5-15 m 3 / h, preferably 5 to 10 m 3 / h; PV is the pore volume of the target oil and gas reservoir; Preferably, The nutrient is selected from at least one of glucose, acetic acid, propionic acid, ethanol, propanol and a long-chain organic matter with a carbon number greater than 3; preferably, the long-chain organic matter is selected from at least one of cellulose and lignin; More preferably, The nutrients also include acid-base regulators; Still more preferably, the acid-base regulator is selected from at least one of hydrochloric acid and sodium hydroxide.

10. The method for underground in-situ hydrogen production using exogenous functional microorganisms according to claim 2, characterized in that: In step (7), Near the outlet of the production well, a semi-permeable membrane that only allows hydrogen to pass through is installed to achieve on-site separation of the produced hydrogen and directly seal the carbon dioxide in the formation; Preferably, the semipermeable membrane is a polymer membrane, preferably at least one of a polysulfone membrane, a dimethylsiloxane membrane or a polyimide membrane.

11. Use of the method for underground in-situ hydrogen production using exogenous functional microorganisms as claimed in any one of claims 1 to 10 in oil and gas field exploitation.

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