Detection method for in-situ biological gasification of shallow carbon source

Abstract

The invention provides a shallow carbon source in-situ biological gasification detection method, which comprises the following steps: analyzing the composition of a gas product of biological gasification, and carrying out isotope characteristic analysis on part of components in the gas product; regularly extracting gas products of biological gasification and carrying out methane cluster isotope analysis; according to the characteristic change of the gas product, the progress condition of shallow carbon source biological gasification and the breeding condition of microbial flora are analyzed. According to the method, the composition and isotope characteristics of gas products in the shallow carbon source biological gasification process are analyzed on line, methane cluster isotope off-line analysis is carried out regularly, and the characteristic change of the biological gasification products is monitored, so that the progress condition of biological gasification is judged, and the active condition of microbial flora is judged; efficient operation of biological gasification is promoted by adjusting environmental conditions; the method is simple, convenient and rapid to operate, real and reliable in judgment result and suitable for research of multiple types of shallow carbon enrichment areas, and a basis is provided for exploration and exploitation.

Description

Technical Field

[0001] The invention belongs to the field of exploration and development and renewable energy technology, and relates to a detection method for in-situ biogasification of shallow carbon sources, and in particular to a monitoring and detection method for the progress of in-situ biogasification of shallow, difficult-to-mobilize carbon source organic matter. Background Art

[0002] Organic matter is widely distributed in shallow layers and has various types, including coal seams, shale layers, abandoned oil and gas reservoirs with extremely rich organic matter, as well as carbonaceous mudstones with relatively concentrated organic matter content. Since fossil energy is usually buried in strata at a certain depth, some of them are difficult to be mined and utilized using conventional technologies due to various factors such as geology during energy extraction. However, the conversion and utilization of this part of carbon can be achieved by using microorganisms to convert solid, difficult-to-mobilize organic carbon into highly mobile biogas. Using microorganisms to achieve in-situ gasification and studying biogasification products is an emerging research field and direction with broad application prospects. However, considering the extreme activity of microorganisms and the limitations of certain burial depths, it is difficult to monitor the progress of biogasification.

[0003] The biogasification of shallow organic matter requires the use of microorganisms to degrade carbon sources. The current method for monitoring and understanding the progress of biogasification is usually direct monitoring. It was previously used for monitoring biogas digesters. Biogas digesters are generally shallow and mainly distributed in densely populated areas such as villages and villages. Water in the biogas digester can be directly obtained to measure the richness and balance of nutrients in the water, as well as the structure of microbial flora; at the same time, various biological simulation experiments in the laboratory also have the characteristics of easy acquisition and simple operation, and the samples are well homogenized and highly representative. However, the direct sampling and detection method has certain difficulties for underground in-situ biogasification projects. The depth of underground in-situ gasification can reach 1000-2000 meters, and sampling is difficult and extremely inconvenient to operate; more importantly, due to the extremely fast reproduction speed of microorganisms, as conditions change, the types and abundance of microorganisms change rapidly, and the sampling process can undergo several generations of microorganisms in a short period of time, which cannot truly and objectively reflect the underground situation; coupled with the strong heterogeneity of the underground, the samples obtained can only represent the situation at the sampling location, but not the whole.

[0004] In order to avoid the problem of mismatch between the detected products and the actual conditions of the formation and the state of the microorganisms, isotope labeling methods are currently used to understand the biogasification situation, such as investing in 14 C-labeled nutrient substrate, if the produced natural gas contains 14 C-labeled methane indicates that biogasification is in progress. The higher the percentage of labeled methane, the higher the degree of biogasification. However, biomethane production pathways are diverse. Unlike the relatively single nutrient substrate in the laboratory and the controllable biomethane production pathway, the nutrient substrates in the carbon source layer in nature are diverse.14 Although the C-marked part can indicate that biomethane is produced during the gasification process, it cannot reflect the progress of biogasification; and 14 The C test is more expensive and requires a large amount of sample, resulting in higher costs and increased difficulty in analysis.

[0005] CN 115182724A discloses a shale gas potential prediction method and device, which includes: analyzing the composition of the obtained natural gas sample to determine the natural gas composition and the absolute content of the wet gas component; performing isotope analysis on the components of the natural gas to determine the carbon and hydrogen isotope inversion amplitude of methane and ethane; performing non-fractionation enrichment and purification treatment and test analysis on the methane in the natural gas to determine the methane cluster isotope; and comprehensively predicting the shale gas production area and potential based on the absolute content of the wet gas component, the carbon and hydrogen isotope inversion amplitude and the methane cluster isotope. Although this method also analyzes and detects natural gas, it is aimed at the output of shale gas in shale reservoirs, and does not involve the composition and breeding of microbial flora and the judgment of the biogasification process, and the characteristics to be detected are also different.

[0006] CN 106249312A discloses a method for quantitatively characterizing the mixed source ratio of shallow gas in an oil and gas basin, the method comprising: determining the genesis and composition type of shallow gas; deriving a methane carbon isotope variation curve of crude oil degradation gas; determining the methane carbon isotope ratio of thermogenic gas; determining the methane carbon isotope ratio of crude oil degradation gas; and quantitatively analyzing the mixed source ratio of shallow gas. The method quantitatively analyzes thermogenic gas and crude oil degradation gas generated during crude oil degradation through a methane carbon isotope variation model, but does not determine the composition of microbial flora, and the characteristics of shallow gas detection are also different, so the progress of biogasification cannot be determined.

[0007] In summary, in order to judge the progress of in situ biogasification of shallow carbon sources, it is also necessary to conduct chromatographic and isotopic analysis and detection of the natural gas produced by biogasification. By understanding the changes in the characteristics of natural gas, we can understand the changes in the structure of underground microbial flora, judge the progress of biogasification, and improve the accuracy of detection. Summary of the invention

[0008] In view of the problems existing in the prior art, the purpose of the present invention is to provide a detection method for in situ biogasification of shallow carbon sources. The method performs in situ biogasification of shallow carbon sources, performs online analysis of the composition and isotopic characteristics of the gas products, and regularly performs offline analysis of methane cluster isotopes. The composition and reproduction of the microbial flora are determined by the changes in the above characteristics, and the progress of biogasification is thereby determined.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] The present invention provides a method for detecting in-situ biogasification of shallow carbon sources, the detection method comprising the following steps:

[0011] (1) Analyze the composition of gas products during biogasification and perform isotopic analysis on some of the components;

[0012] (2) Regularly perform methane cluster isotope analysis on the gas products of biogasification;

[0013] (3) Analyze the progress of shallow carbon source biogasification and the growth of microbial flora based on the characteristic changes of the gas products in steps (1) and (2).

[0014] In the present invention, according to the energy types distributed in the shallow layer, a microbial biogasification method is used for research, so as to provide a basis for subsequent exploration and exploitation, and thus the progress of biogasification needs to be monitored; in the present invention, in-situ biogasification is performed on the shallow carbon source, and composition analysis and conventional isotope characteristic analysis are performed on the gas products, and the gas products are regularly collected for methane cluster isotope analysis, the former is performed online, and the latter is performed offline, and the characteristic changes of the biogasification products are monitored by combining the two, and the progress of biogasification can be judged. At the same time, the activity of different types of microbial flora can also be judged, and the environmental conditions in the shallow layer can be adjusted when necessary to meet the growth requirements of different microorganisms and promote the efficient operation of biogasification; the method is simple and fast to operate, and the judgment result is true and reliable, which can be applied to the research of shallow multi-type carbon enrichment areas, and provide a basis for exploration and exploitation.

[0015] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0016] As a preferred technical solution of the present invention, the types of shallow carbon sources include any one of coal seams, shale layers, oil and gas reservoirs or carbonaceous mudstones, or a combination of at least two of them. Typical but non-limiting examples of the combinations include: a combination of coal seams and shale layers, a combination of shale layers and oil and gas reservoirs, a combination of coal seams, shale layers and carbonaceous mudstones, a combination of shale layers, oil and gas reservoirs and carbonaceous mudstones, a combination of coal seams, shale layers, oil and gas reservoirs and carbonaceous mudstones, and the like.

[0017] Preferably, the depth of the shallow carbon source is within 2000m, for example 2000m, 1750mm, 1500m, 1350m, 1200m, 1000m, 800m, 600m, 400m or 200m, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 200-1800m.

[0018] Preferably, the temperature of the shallow carbon source is controlled below 80°C, for example 80°C, 70°C, 65°C, 60°C, 55°C, 50°C, 40°C or 30°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably below 65°C.

[0019] The biogasification in the present invention is the in-situ biogasification of difficult-to-mobilize organic matter by microorganisms. The shallow carbon source is selected mainly because if the depth is too large or the temperature exceeds 80°C, the activity of the microorganisms is greatly limited and efficient conversion cannot be achieved.

[0020] As a preferred technical solution of the present invention, the gas product in the biogasification process in step (1) is a natural gas product.

[0021] Preferably, the composition of the gas product includes N 2 , H 2 , CH 4 and CO 2 .

[0022] Preferably, the composition of the gas product also includes H 2 S and / or C 2 The above gaseous alkanes, the C 2 The above gaseous alkanes are preferably C 2 H 6 .

[0023] As a preferred technical solution of the present invention, the components for isotope characteristic analysis in step (1) include CH 4 , CO 2 and C 2 H 6 .

[0024] Preferably, the isotopic signature analysis includes CH 4 , CO 2 and C 2 H 6 Stable carbon isotopes and CH 4 and C 2 H 6 Stable hydrogen isotopes.

[0025] In the present invention, the isotopic characteristics are selected from the stable isotopes of the corresponding elements, and the selection is mainly based on the order from simple to difficult, that is, stable carbon isotope, stable hydrogen isotope and cluster isotope analysis.

[0026] As a preferred technical solution of the present invention, the composition of the gas product in step (1) is analyzed online by chromatography, and the isotope characteristics are analyzed online by isotope mass spectrometry.

[0027] Preferably, the chromatography is performed using a gas chromatograph, and the isotope mass spectrometry is performed using a chromatography-isotope mass spectrometer.

[0028] As a preferred technical solution of the present invention, the methane cluster isotopes in step (2) include 13 CH 3 D and 12 CH 2 D 2 The result of the isotope analysis is the isotope ratio data, which mainly compares the differences between the data before and after to determine the changes in gas products and the progress of biogasification.

[0029] Preferably, the methane cluster isotope analysis is performed by periodically collecting gas products and then performing offline analysis, and the interval between regular collection is 1 to 30 days, for example, 1 day, 3 days, 7 days, 10 days, 14 days, 21 days, 28 days or 30 days, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] Preferably, the equipment used for the methane cluster isotope analysis is a high-resolution isotope mass spectrometer, and the available models include MAT-253Ultra, Panorama, etc.

[0031] Preferably, the gas product is divided into two branches by a three-way connection assembly, one branch is used for online analysis of composition and isotopic characteristics in step (1), and the other branch is used for offline sample collection and subsequent analysis of methane cluster isotopes in step (2).

[0032] As a preferred technical solution of the present invention, the gas product contains C 2 H 6 When, according to C 2 H 6 Whether the carbon isotope characteristics are stable can be used to determine whether degradation has occurred, thereby judging the progress of biogasification.

[0033] Preferably, if C 2 H 6 The carbon isotope characteristics are stable. 2 H 6 The change in relative proportions clearly determines the progress of biogasification.

[0034] In the present invention, the natural gas product of biogasification contains C 2 H 6 When the collected airflow contains thermogenic gas, it also contains C 2 H 6Heavy hydrocarbon gases such as chlorinated hydrocarbons mainly come from coal seam gas production areas. Since the above heavy hydrocarbon gases will not be produced during the biogasification process, but they will undergo biodegradation themselves, this degradation will lead to C 2 H 6 The stable carbon isotope value quickly becomes heavier, if C 2 H 6 If the carbon isotope characteristics are stable (the variation range does not exceed 0.5‰), it can be considered that no obvious degradation has occurred.

[0035] At this time, according to the natural gas products collected at different times i and the components in the initial natural gas, C 2 H 6 Changes in relative ratios, such as methane / ethane (C 1 / C 2 ) ratio increases significantly, the multiple of newly generated methane can be calculated, Q = (C 1 / C 2 ) i / (C 1 / C 2 ) 0 , clearly judge the progress of biogasification.

[0036] As a preferred technical solution of the present invention, the gas product does not contain C 2 H 6 During the biogasification process, the components in the gas products will change due to generation or consumption. The progress of biogasification can be judged based on the changes in the component content and isotopic characteristics of the gas products.

[0037] In the present invention, the natural gas product does not contain C 2 H 6 Large molecular weight alkanes or C 2 H 6 It has been subjected to strong biodegradation, which means that the main components in natural gas may change due to generation or consumption during the biogasification process, and there is a lack of a direct reference system. In this case, it is determined based on the changes in the composition of the natural gas products over time and combined with the isotopic characteristics.

[0038] Preferably, the CH 4 Increased CH 4 The stable hydrogen isotope becomes lighter or CH 4 When at least two of the cluster isotope decreases are satisfied, the biogasification develops benignly.

[0039] In the present invention, if CH 4 When the content in natural gas increases (>5%), CH 4 Stable hydrogen isotopes become lighter, CH 4 Cluster isotope (Δ 13CH 3 D and Δ 12 CH 2 D 2 ) become smaller or negative at the same time, indicating that biogasification is developing well. It is easy to judge that biogasification is progressing well if the above conditions are met at the same time. However, in most cases, the first two conditions change slightly (probably within the error range). However, as long as biogasification progresses, CH 4 Cluster isotopes will have systematic changes, mainly due to Δ 13 CH 3 D and Δ 12 CH 2 D 2 The value is more sensitive to methane. By comparing different well areas, we can understand the differences in the progress of biogasification.

[0040] Preferably, the CO 2 The content of CH 4 The content of CH 4 When the isotopes do not change significantly or change negatively, the activity of methanogens is not high and biogasification progresses poorly.

[0041] As a preferred technical solution of the present invention, when the biogasification progress is not good, if the H 2 The abundance is high, the microorganisms are mainly organic matter degrading bacteria, and the activity of methanogens is poor. At this time, the microenvironment in the shallow layer is adjusted and the nutrients required by methanogens, such as trace elements, are added.

[0042] In the present invention, organic matter degrading bacteria can be divided into macromolecular degrading bacteria and small molecule degrading bacteria, such as Clostridium, Micrococcus, Bacteroides, Butyrivibrio, Streptococcus, Lactobacillus, Bacillus and Salmonella.

[0043] In the present invention, when the biogasification progress is poor, the product contains rich H 2 , which means that the underground bacterial community is dominated by bacteria that consume organic matter, and archaea such as methanogens are less active and cannot consume necessary products, resulting in H 2 and CO 2 High abundance enrichment; at this time, it is necessary to adjust the underground microenvironment and take targeted measures to stimulate the activity of methanogens, such as inputting trace elements required by methanogens; according to the direction and amplitude of the change of methane cluster isotopes, the type of methanogens can be determined. For different bacterial communities, such as acetic acid fermentation archaea, H 2 Reduction of CO 2 Archaea have different requirements for nutritional substrates.

[0044] Preferably, if the gas product contains only CO 2 The abundance of H 2Low content, CO 2 The isotopes are normal. At this time, the abundance of fermentation bacteria is too high and the activity of hydrogen-producing bacteria is insufficient. The environmental conditions are adjusted to meet the growth requirements of hydrogen-producing bacteria.

[0045] In the present invention, if the natural gas product contains only CO 2 , no or little H 2 , CO 2 The isotope is normal, generally >-30‰. In this case, the abundance of fermentation bacteria is too high and the activity of hydrogen-producing bacteria is insufficient. It is necessary to adjust the environmental conditions to stimulate the reproduction of the bacteria and promote the biogasification process based on the special living requirements of hydrogen-producing bacteria.

[0046] Preferably, if the gas product contains CO 2 The abundance of H 2 Low content, CO 2 The isotope becomes lighter, and CH 4 Being consumed and oxidized by microorganisms is not conducive to biogasification. Obtain groundwater and rock samples, carry out targeted research, identify the adverse factors causing biogasification, eliminate hidden dangers and adjust the microenvironment.

[0047] In the present invention, if the abundance of CO 2 , no or little H 2 , CO 2 If the isotope gradually becomes lighter, or even exceeds the possible range of organic matter degradation sources (generally -25 to -35‰), it indicates that methane is consumed and oxidized by microorganisms, which is even more unfavorable for biogasification. This process will also cause the methane carbon isotope to become heavier, and the methane cluster isotope will easily become very heavy. The surface temperature corresponding to the methane cluster isotope is developing in a decreasing direction. In this case, it is urgent to carry out targeted research, obtain groundwater and rock samples, and find out whether the rock formation contains oxides, sulfates or other salts, such as nitrates, to eliminate possible hidden dangers in a timely manner and adjust the microenvironment.

[0048] As a preferred technical solution of the present invention, the detection method comprises the following steps:

[0049] (1) Analyze the composition of natural gas, a gas product produced during biogasification. The composition of the gas product includes N 2 , H 2 , CH 4 and CO 2 , also includes H 2 S and / or C 2 H 6 , and some of the components CH 4 , CO 2 and C 2 H 6Perform isotopic signature analysis, including CH 4 , CO 2 and C 2 H 6 Stable carbon isotopes and CH 4 and C 2 H 6 The composition of the gas product is analyzed online by chromatography, and the isotope characteristics are analyzed online by isotope mass spectrometry;

[0050] (2) The gas products of biogasification are collected regularly for offline methane cluster isotope analysis, with the interval of regular collection being 1 to 30 days. The methane cluster isotopes include 13 CH 3 D and 12 CH 2 D 2 The gas product is divided into two branches by a three-way connection assembly, one branch is used for online analysis of the composition and isotopic characteristics in step (1), and the other branch is used for offline collection and analysis of methane cluster isotopes in step (2);

[0051] (3) According to the characteristics of the gas product in steps (1) and (2), the gas product contains C 2 H 6 When, according to C 2 H 6 Whether the carbon isotope characteristics are stable can be used to determine whether degradation has occurred, thereby judging the progress of biogasification; if C 2 H 6 The carbon isotope characteristics are stable. 2 H 6 The change of relative proportions clearly determines the progress of biogasification;

[0052] The gas product does not contain C 2 H 6 During the biogasification process, the components in the gas products will change due to generation or consumption. The progress of biogasification can be judged based on the changes in the component content and isotopic characteristics of the gas products. 4 Increased CH 4 The stable hydrogen isotope becomes lighter or CH 4 When at least two of the cluster isotope decreases are satisfied, the biogasification develops benignly; the CO 2 The content of CH 4 The content of CH 4 If the isotope does not change significantly or changes negatively, the activity of methanogens is not high and the biogasification progress is poor. If the biogasification progress is poor, the H2 The abundance is high, the microorganisms are mainly organic matter degrading bacteria, and the activity of methanogens is poor. At this time, the microenvironment in the shallow layer is adjusted and the trace elements required by methanogens are added; if there is only CO in the gas product 2 The abundance of H 2 Low content, CO 2 The isotope is normal. At this time, the abundance of fermentation bacteria is too high and the activity of hydrogen-producing bacteria is insufficient. The environmental conditions should be adjusted to meet the growth requirements of hydrogen-producing bacteria. 2 The abundance of H 2 Low content, CO 2 The isotope becomes lighter, and CH 4 Being consumed and oxidized by microorganisms is not conducive to biogasification. Obtain groundwater and rock samples, carry out targeted research, identify the adverse factors causing biogasification, eliminate hidden dangers and adjust the microenvironment.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) The method of the present invention performs in-situ biogasification of shallow carbon sources, performs online analysis of the composition and isotopic characteristics of gas products, and regularly performs offline analysis of methane cluster isotopes. The combination of the two can monitor the characteristic changes of biogasification products, judge the progress of biogasification, and also judge the activity of different types of microbial flora. If necessary, the environmental conditions in the shallow layer can be adjusted to meet the growth requirements of different microorganisms, thereby promoting the efficient operation of biogasification.

[0055] (2) The method of the present invention is simple and quick to operate, and the judgment results are true and reliable. It can be applied to the study of shallow multi-type carbon-enriched areas and provide a basis for exploration and exploitation. DETAILED DESCRIPTION

[0056] In order to better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention is further described in detail below. However, the following embodiments are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0057] The specific implementation method of the present invention provides a method for detecting in-situ biogasification of shallow carbon sources, and the detection method comprises the following steps:

[0058] (1) Analyze the composition of gas products during biogasification and perform isotopic analysis on some of the components;

[0059] (2) Regularly perform methane cluster isotope analysis on the gas products of biogasification;

[0060] (3) Analyze the progress of shallow carbon source biogasification and the growth of microbial flora based on the characteristic changes of the gas products in steps (1) and (2).

[0061] The following are typical but non-limiting embodiments of the present invention:

[0062] Embodiment 1:

[0063] This embodiment provides a detection method for in-situ biogasification of a shallow carbon source, wherein the shallow carbon source is a coal seam, and the depth range of the shallow carbon source is 1000 to 1500 m. The detection method comprises the following steps:

[0064] (1) Analyze the composition of natural gas, a gas product of biogasification, wherein the composition of the gas product includes N 2 , H 2 , CH 4 , CO 2 , H 2 S and C 2 H 6 , and some of the components CH 4 , CO 2 and C 2 H 6 Perform isotopic characterization, including CH 4 , CO 2 and C 2 H 6 Stable carbon isotopes and CH 4 and C 2 H 6 The composition of the gas product is analyzed online by chromatography, and the isotope characteristics are analyzed online by isotope mass spectrometry;

[0065] (2) The gas products of biogasification are collected regularly for offline methane cluster isotope analysis at an interval of 7 days. The methane cluster isotopes include 13 CH 3 D and 12 CH 2 D 2 The gas product is divided into two branches by a three-way connection assembly, one branch is used for online analysis of the composition and isotopic characteristics in step (1), and the other branch is used for offline collection and analysis of methane cluster isotopes in step (2);

[0066] (3) According to the characteristic changes of the gas products in steps (1) and (2), C 2 H 6 Whether the carbon isotope characteristic changes within a range of more than 0.5‰ determines whether it is stable, and thus determines whether it has degraded, and thus determines the progress of biogasification; C 2H 6 The carbon isotope characteristics are stable, with a variation range of no more than 0.5‰. 2 H 6 The change in relative proportions clearly determines the progress of biogasification.

[0067] Embodiment 2:

[0068] This embodiment provides a detection method for in-situ biogasification of a shallow carbon source, wherein the shallow carbon source is a shale layer, and the depth range of the shallow carbon source is 800 to 1200 m. The detection method comprises the following steps:

[0069] (1) Analyze the composition of natural gas, a gas product of biogasification, wherein the composition of the gas product includes N 2 , H 2 , CH 4 , CO 2 and H 2 S, and some of its components CH 4 and CO 2 Stable carbon isotope characteristics analysis was performed to determine CH 4 Performing stable hydrogen isotope characteristic analysis; the composition of the gas product is analyzed online by chromatography, and the isotope characteristic is analyzed online by isotope mass spectrometry;

[0070] (2) The gas products of biogasification are collected regularly for offline methane cluster isotope analysis at an interval of 14 days. The methane cluster isotopes include 13 CH 3 D and 12 CH 2 D 2 The gas product is divided into two branches by a three-way connection assembly, one branch is used for online analysis of composition and isotopic characteristics in step (1), and the other branch is used for offline collection and analysis of methane cluster isotopes in step (2);

[0071] (3) Since the gas product does not contain C 2 H 6 The components in the gas products will change due to generation or consumption during the biogasification process. The progress of biogasification can be judged based on the changes in the component content and isotopic characteristics of the gas products. After detection and analysis, CH 4 The stable hydrogen isotopes become lighter and CH 4 The cluster isotopes become smaller and the biogasification develops benignly.

[0072] Embodiment 3:

[0073] This embodiment provides a detection method for in-situ biogasification of a shallow carbon source, wherein the shallow carbon source is a shale layer, and the depth range of the shallow carbon source is 800 to 1200 m. The detection method comprises the following steps:

[0074] (1) Analyze the composition of natural gas, a gas product of biogasification, wherein the composition of the gas product includes N 2 , H 2 , CH 4 , CO 2 and H 2 S, and some of its components CH 4 and CO 2 Stable carbon isotope characteristics analysis was performed to determine CH 4 Performing stable hydrogen isotope characteristic analysis; the composition of the gas product is analyzed online by chromatography, and the isotope characteristic is analyzed online by isotope mass spectrometry;

[0075] (2) The gas products of biogasification are collected regularly for offline methane cluster isotope analysis at an interval of 14 days. The methane cluster isotopes include 13 CH 3 D and 12 CH 2 D 2 The gas product is divided into two branches by a three-way connection assembly, one branch is used for online analysis of the composition and isotopic characteristics in step (1), and the other branch is used for offline collection and analysis of methane cluster isotopes in step (2);

[0076] (3) Since the gas product does not contain C 2 H 6 The components in the gas products will change due to generation or consumption during the biogasification process. The progress of biogasification can be judged based on the changes in the component content and isotopic characteristics of the gas products. 2 The content increased from 11% to 37% within half a month, while CH 4 The content decreased from 86% to 54%, CH 4 There is no significant change in isotopes, and H 2 The abundance is relatively high, increasing from 0.2% to 6.2%. The microorganisms are mainly bacteria that consume organic matter, and the activity of methanogens is relatively poor. At this time, the microenvironment in the shallow layer is adjusted and trace elements required to stimulate methanogens are added.

[0077] Embodiment 4:

[0078] This embodiment provides a method for detecting in-situ biogasification of a shallow carbon source, wherein the shallow carbon source is an oil and gas reservoir, and the depth range of the shallow carbon source is 500 to 1200 m. The detection method comprises the following steps:

[0079] (1) Analyze the composition of natural gas, a gas product of biogasification, wherein the composition of the gas product includes N 2 , H 2 , CH 4 , CO 2 and H 2 S, and some of its components CH 4 and CO 2 Stable carbon isotope characteristics analysis was performed to determine CH 4 Performing stable hydrogen isotope characteristic analysis; the composition of the gas product is analyzed online by chromatography, and the isotope characteristic is analyzed online by isotope mass spectrometry;

[0080] (2) The gas products of biogasification are collected regularly for offline methane cluster isotope analysis at an interval of 21 days. The methane cluster isotopes include 13 CH 3 D and 12 CH 2 D 2 The gas product is divided into two branches by a three-way connection assembly, one branch is used for online analysis of the composition and isotopic characteristics in step (1), and the other branch is used for offline collection and analysis of methane cluster isotopes in step (2);

[0081] (3) Since the gas product does not contain C 2 H 6 The components in the gas products will change due to generation or consumption during the biogasification process. The progress of biogasification can be judged based on the changes in the component content and isotopic characteristics of the gas products. 2 The content increased to 65%, while CH 4 The content was reduced to 32%, CH 4 There is no significant change in isotopes. 2 The content is small, specifically 1.8%, CO 2 The isotope is normal, which is -22‰. At this time, the abundance of fermentation bacteria is too high and the activity of hydrogen-producing bacteria is insufficient. The environmental conditions are adjusted to meet the growth requirements of hydrogen-producing bacteria.

[0082] Embodiment 5:

[0083] This embodiment provides a detection method for in-situ biogasification of a shallow carbon source, wherein the shallow carbon source is an oil and gas reservoir, and the depth range of the shallow carbon source is 1000 to 2000 m. The detection method comprises the following steps:

[0084] (1) Analyze the composition of natural gas, a gas product of biogasification, wherein the composition of the gas product includes N 2 , H 2 , CH4 and CO 2 , and some of the components CH 4 and CO 2 Stable carbon isotope characteristics analysis was performed to determine CH 4 Performing stable hydrogen isotope characteristic analysis; the composition of the gas product is analyzed online by chromatography, and the isotope characteristic is analyzed online by isotope mass spectrometry;

[0085] (2) The gas products of biogasification are collected regularly for offline methane cluster isotope analysis at an interval of 28 days. The methane cluster isotopes include 13 CH 3 D and 12 CH 2 D 2 The gas product is divided into two branches by a three-way connection assembly, one branch is used for online analysis of the composition and isotopic characteristics in step (1), and the other branch is used for offline collection and analysis of methane cluster isotopes in step (2);

[0086] (3) Since the gas product does not contain C 2 H 6 The components in the gas products will change due to generation or consumption during the biogasification process. The progress of biogasification can be judged based on the changes in the component content and isotopic characteristics of the gas products. 2 The content increased from 9% to 49% within 20 weeks, while CH 4 The content was reduced from 86% to 44%, and H 2 , CO 2 The isotope gradually becomes lighter, from -11.5‰ to -25.6‰. At this time, CH 4 Being consumed and oxidized by microorganisms is not conducive to biogasification. Targeted research should be carried out to obtain groundwater and rock samples to find out whether the rock strata contain oxides, sulfates or nitrates, so as to eliminate possible hidden dangers in a timely manner and adjust the microenvironment.

[0087] From the above embodiments, it can be seen that the method of the present invention performs in-situ biogasification of shallow carbon sources, performs online analysis of the composition and isotopic characteristics of gas products, and regularly performs offline analysis of methane cluster isotopes. The characteristic changes of biogasification products are monitored by combining the two to judge the progress of biogasification. At the same time, the activity of different types of microbial flora can also be judged. When necessary, the environmental conditions in the shallow layer can be adjusted to meet the growth requirements of different microorganisms and promote the efficient operation of biogasification. The method is simple and fast to operate, and the judgment results are true and reliable. It can be applied to the study of shallow multi-type carbon-enriched areas and provide a basis for exploration and exploitation.

[0088] The applicant declares that the present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the method of the present invention, addition of auxiliary methods, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for detecting in-situ biogasification of shallow carbon sources, characterized in that: The detection method comprises the following steps: (1) Analyze the composition of gas products during biogasification and perform isotopic analysis on some of the components; (2) Regularly perform methane cluster isotope analysis on the gas products of biogasification; (3) Analyze the progress of shallow carbon source biogasification and the growth of microbial flora based on the characteristic changes of the gas products in steps (1) and (2).

2. The detection method according to claim 1, characterized in that: The shallow carbon source includes any one of coal seams, shale layers, oil and gas reservoirs, or carbonaceous mudstones, or a combination of at least two of them; Preferably, the depth of the shallow carbon source is within 2000 m, preferably 200 to 1800 m; Preferably, the temperature of the shallow carbon source is controlled below 80°C, preferably below 65°C.

3. The detection method according to claim 1 or 2, characterized in that: The gas product in the biogasification process of step (1) is a natural gas product; Preferably, the composition of the gas product includes N2, H2, CH4 and CO2; Preferably, the composition of the gas product also includes H2S and / or gaseous alkanes above C2, and the gaseous alkanes above C2 are preferably C2H6.

4. The detection method according to any one of claims 1 to 3, characterized in that: The components subjected to isotopic characteristic analysis in step (1) include CH4, CO2 and C2H6; Preferably, the isotopic signature analysis includes stable carbon isotopes of CH4, CO2 and C2H6 and stable hydrogen isotopes of CH4 and C2H6.

5. The detection method according to any one of claims 1 to 4, characterized in that: The composition of the gas product in step (1) is analyzed online by chromatography, and the isotope characteristics are analyzed online by isotope mass spectrometry; Preferably, the chromatography is performed using a gas chromatograph, and the isotope mass spectrometry is performed using a chromatography-isotope mass spectrometer.

6. The detection method according to any one of claims 1 to 5, characterized in that: The methane cluster isotopes in step (2) include 13 CH3D and 12 CH2D2; Preferably, the methane cluster isotope analysis is performed by regularly collecting gas products and then performing offline analysis, and the interval between regular collections is 1 to 30 days; Preferably, the equipment used for the methane cluster isotope analysis is a high-resolution isotope mass spectrometer; Preferably, the gas product is divided into two branches by a three-way connection assembly, one branch is used for online analysis of composition and isotopic characteristics in step (1), and the other branch is used for offline sample collection and subsequent analysis of methane cluster isotopes in step (2).

7. The detection method according to any one of claims 3 to 6, characterized in that: When the gas product contains C2H6, judging whether it has been degraded is based on whether the carbon isotope characteristics of C2H6 are stable, thereby judging the progress of biogasification; Preferably, if the carbon isotope characteristics of C2H6 are stable, the progress of biogasification can be clearly judged based on the changes in the relative proportions of C2H6 of each component in the gas products collected at different times.

8. The detection method according to any one of claims 3 to 7, characterized in that: When the gas product does not contain C2H6, the components in the gas product will change due to generation or consumption during the biogasification process, and the progress of the biogasification can be judged based on the changes in the component content and isotopic characteristics of the gas product; Preferably, when at least two of the following conditions are met: the CH4 content increases, the stable hydrogen isotope of CH4 becomes lighter, or the CH4 cluster isotope becomes smaller, the biogasification develops benignly; Preferably, the CO2 content increases, while the CH4 content decreases, and the CH4 isotope does not change significantly or changes negatively. At this time, the activity of methanogens is not high and the biogasification progress is poor.

9. The detection method according to claim 8, characterized in that: In the case where the biogasification progress is not good, if the H2 abundance in the product is high, the microorganisms are mainly organic matter degrading bacteria, and the activity of methanogens is poor. At this time, the microenvironment in the shallow layer is adjusted and the nutrients required by methanogens are added; Preferably, if only CO2 abundance is high in the gas product, while H2 content is low and CO2 isotope is normal, then the abundance of fermentation bacteria is too high and the activity of hydrogen-producing bacteria is insufficient, and the environmental conditions are adjusted to meet the growth requirements of hydrogen-producing bacteria; Preferably, if the CO2 abundance in the gas product is high and the H2 content is low, the CO2 isotope becomes lighter. At this time, CH4 is consumed and oxidized by microorganisms, which is not conducive to biogasification. Obtain groundwater and rock samples, carry out targeted research, identify the adverse factors causing biogasification, eliminate hidden dangers and adjust the microenvironment.

10. The detection method according to any one of claims 1 to 9, characterized in that: The detection method comprises the following steps: (1) Analyzing the composition of natural gas, a gas product produced during biogasification, wherein the composition of the gas product includes N2, H2, CH4 and CO2, and also includes H2S and / or C2H6, and performing isotope characteristic analysis on some of the components, CH4, CO2 and C2H6, wherein the isotope characteristic analysis includes stable carbon isotopes of CH4, CO2 and C2H6 and stable hydrogen isotopes of CH4 and C2H6; the composition of the gas product is analyzed online by chromatography, and the isotope characteristic is analyzed online by isotope mass spectrometry; (2) The gas products of biogasification are regularly collected for offline methane cluster isotope analysis at intervals of 1 to 30 days. The methane cluster isotopes include 13 CH3D and 12 CH2D2; the gas product is divided into two branches by a three-way connection assembly, one branch is used for online analysis of composition and isotopic characteristics in step (1), and the other branch is used for offline collection and analysis of methane cluster isotopes in step (2); (3) According to the characteristic changes of the gas products in steps (1) and (2), when the gas products contain C2H6, judging whether it has been degraded is based on whether the carbon isotope characteristics of C2H6 are stable, thereby judging the progress of biogasification; if the carbon isotope characteristics of C2H6 are stable, judging the progress of biogasification is based on the changes in the relative proportions of C2H6 in the gas products collected at different times; When the gas product does not contain C2H6, the components in the gas product will change due to generation or consumption during the biogasification process. The progress of biogasification can be judged based on the changes in the component content and isotopic characteristics of the gas product. When at least two of the following conditions are met: the CH4 content increases, the stable hydrogen isotope of CH4 becomes lighter, or the CH4 cluster isotope becomes smaller, the biogasification develops benignly. When the CO2 content increases, while the CH4 content decreases, and the CH4 isotope does not change significantly or changes negatively, the activity of methanogens is not high and the biogasification progresses poorly. When the biogasification progresses poorly, if the H2 abundance in the product is high, the microorganisms are The main organisms are organic matter-degrading bacteria, and the activity of methanogens is relatively poor. At this time, adjust the microenvironment in the shallow layer and add trace elements required by methanogens. If only CO2 abundance is high in the gas products, while H2 content is low and CO2 isotopes are normal, then the abundance of fermentation-type bacteria is too high and the activity of hydrogen-producing bacteria is insufficient. Adjust the environmental conditions to meet the growth requirements of hydrogen-producing bacteria. If CO2 abundance is high in the gas products, while H2 content is low and CO2 isotopes become lighter, then CH4 is consumed and oxidized by microorganisms, which is not conducive to biogasification. Obtain groundwater and rock samples, carry out targeted research, identify the adverse factors causing biogasification, eliminate hidden dangers and adjust the microenvironment.