Natural hydrogen cause identification method based on cluster isotope

Abstract

The invention discloses a natural hydrogen formation cause identification method based on cluster isotope, which comprises the following steps: obtaining a purified hydrogen sample to be detected through separation and purification treatment; performing cluster isotope measurement on the purified hydrogen sample to obtain a cluster isotope value representing the abundance deviation random distribution degree of the dideuterium molecules; when it is judged that the cluster isotope value is in the original thermodynamic equilibrium state, the formation temperature of the purified hydrogen sample is inverted according to the theoretical function relation between the cluster isotope value and the thermodynamic equilibrium temperature; and comparing the formation temperature with a pre-established formation temperature range of different cause types of natural hydrogen, and determining the cause type of the purified hydrogen sample. According to the method, the cluster isotope delta DD is introduced as an anti-interference core index, and multi-source information verification and temperature quantitative inversion are combined, so that a fundamental breakthrough of the natural hydrogen cause from qualitative speculation to accurate quantitative judgment is realized.

Description

Technical Field

[0001] This invention belongs to the field of geochemistry and isotope geology, and particularly relates to a method for identifying the origin of natural hydrogen based on cluster isotopes. Background Technology

[0002] Natural hydrogen, due to its clean and high energy density, is considered an important potential energy source to replace traditional fossil fuels. However, to achieve its large-scale exploration and effective development, the fundamental geological problem of determining its origin must first be solved. Accurately identifying the source and formation mechanism of hydrogen is not only a prerequisite for understanding its distribution patterns, but also a scientific basis for evaluating resource potential and guiding exploration deployment.

[0003] Currently, the determination of the origin of natural hydrogen mainly relies on two existing technical methods. The first is hydrogen isotope composition analysis, which infers its origin by measuring the relative abundance of deuterium (D) and hydrogen (H) in hydrogen gas (usually expressed as δD values). Different genetic processes (such as microbial activity, water-rock reaction, and deep degassing) theoretically produce hydrogen gas with specific δD value ranges. However, hydrogen gas is highly chemically reactive and readily undergoes extensive isotope exchange reactions with formation water, mineral surfaces, and microorganisms during its migration from its formation site to the reservoir and even during its later preservation. This process leads to a significant fractionation effect of hydrogen isotopes, causing the measured δD values ​​to often not represent the characteristics of its original formation but rather reflect the results of subsequent alterations, thus severely weakening the reliability and accuracy of this method.

[0004] The second type of method is the indirect inference method based on the characteristics of associated gas components. This method indirectly infers the source and environment of hydrogen by analyzing the chemical and isotopic composition of other gases associated with hydrogen (such as methane, helium, and nitrogen). For example, the presence of mantle-derived helium may be associated with deep inorganic-origin hydrogen, while the presence of biogenic methane may suggest that the related hydrogen has an organic origin. Although this method can provide supplementary genetic clues to some extent and can be used for cross-validation, it is essentially indirect evidence, and its interpretation is subject to multiple interpretations. Different genetic processes may produce similar associated gas combinations, and even the same genetic process may result in variations in associated gas composition due to environmental differences. Furthermore, the discriminative ability of this method is particularly limited for some gas reservoirs that lack characteristic associated gases or have undergone complex mixing.

[0005] In summary, existing technical methods—whether the direct but easily modified hydrogen isotope method or the indirect and multifaceted associated gas component method—have significant shortcomings. They are unable to effectively resist the physicochemical transformations that hydrogen undergoes in later geological history, and cannot provide direct, robust, and unique genetic identification indicators. This technical bottleneck restricts the accurate understanding of the formation mechanism of natural hydrogen, especially deep inorganic hydrogen with complex origins, and also hinders breakthroughs in related exploration technologies.

[0006] Therefore, there is an urgent need in this field to develop a new causal identification technology that can more directly record the original formation conditions, is less affected by later interference, and can improve the accuracy of discrimination. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for identifying the origin of natural hydrogen based on cluster isotopes, comprising the following steps: A purified hydrogen sample to be tested was obtained through separation and purification. Cluster isotope measurements were performed on the purified hydrogen sample to obtain cluster isotope values ​​characterizing the degree to which the abundance of dideuterium molecules deviates from a random distribution. When it is determined that the cluster isotope value is in the original thermodynamic equilibrium state, the formation temperature of the purified hydrogen sample can be deduced based on the theoretical functional relationship between the cluster isotope value and the thermodynamic equilibrium temperature. The formation temperature is compared with the pre-established formation temperature range of natural hydrogen of different origin types to determine the origin type of the purified hydrogen sample.

[0008] Optionally, a purified hydrogen sample to be tested is obtained through separation and purification processes, specifically including: A liquid nitrogen cryogenic enrichment method is used to process natural hydrogen samples containing impurities. By utilizing the difference in boiling points between hydrogen and impurity gases, the impurity gases are condensed and retained under low-temperature conditions, thereby keeping the hydrogen components in a gaseous state and allowing them to flow out through a carrier gas, thus achieving the physical separation and purification of hydrogen. The impurity gases include methane, nitrogen, and helium.

[0009] Optionally, cluster isotope measurements are performed on the purified hydrogen sample to obtain cluster isotope values ​​characterizing the degree to which the abundance of its dideuterium molecules deviates from a random distribution, specifically including: Using a high-resolution stable isotope mass spectrometer, the signal intensities of the ordinary hydrogen molecular ion beam, hydrogen deuterium molecular ion beam, and double deuterium molecular ion beam in the purified hydrogen sample were measured sequentially using the peak skipping method, and the background signal was subtracted. The hydrogen isotope δD value of the sample was calculated based on the measured signal intensity ratio between hydrogen deuterium molecules and ordinary hydrogen molecules. Based on the measured signal intensity ratio between the dideuterium molecule and the ordinary hydrogen molecule, the δDD value of the dideuterium molecule in the sample was calculated. Based on the benchmark measurement method established by the heating equilibrium experiment, the cluster isotope ΔDD value of the purified hydrogen sample is calculated using a reference gas that has undergone high-temperature thermodynamic equilibrium treatment.

[0010] Optionally, determining whether the cluster isotope values ​​of the purified hydrogen sample are in the original thermodynamic equilibrium state specifically includes comprehensive identification using at least one of the following methods: Based on the joint analysis of cluster isotope values ​​and hydrogen isotope values, it is determined whether they are within the theoretical equilibrium relationship curve or its error range. Based on the consistency characteristics of hydrogen isotope values ​​and cluster isotope values ​​of different samples within the same geological unit, it can be determined whether they have undergone an isotope homogenization process. Indirect inferences can be made based on the geochemical characteristics of associated gases, including determining the gas source depth by the helium isotope ratio of associated helium, or inferring whether hydrogen has undergone a later reset by analyzing the cluster isotope balance of associated methane. By combining regional geological background and reservoir temperature information, a comprehensive analysis is conducted to determine whether the temperature indicated by cluster isotopes matches the current geothermal temperature or the temperature of ancient hydrothermal activity in the reservoir.

[0011] Optionally, the formation temperature of the purified hydrogen sample can be derived by inverting the theoretical functional relationship between cluster isotope values ​​and thermodynamic equilibrium temperature, specifically including: The theoretical functional relationship is established in advance by obtaining energy level data of hydrogen molecules, deuterium molecules, and hydrogen-deuterium molecules through quantum chemical calculations, calculating the thermodynamic equilibrium constant of isotope exchange reactions at different temperatures, and converting the equilibrium constant into a functional relationship between cluster isotope values ​​and temperature.

[0012] Optionally, the pre-established temperature ranges for the formation of natural hydrogen of different genetic types include: the temperature range corresponding to hydrogen production by microorganisms, the temperature range corresponding to hydrogen production by thermal evolution of organic matter, the temperature range corresponding to hydrogen production by water-rock reaction of iron-bearing minerals, the temperature conditions corresponding to hydrogen production by radiation decomposition of water, and the temperature range corresponding to hydrogen production by water free radical decomposition related to rock fragmentation.

[0013] Optionally, after determining the preliminary origin type of the purified hydrogen sample, a multi-dimensional comprehensive analysis is conducted by combining the hydrogen isotope data of the purified hydrogen sample and the component characteristics of its associated gas to ultimately determine its origin type.

[0014] On the other hand, the present invention also provides a computer device including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method.

[0015] On the other hand, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method.

[0016] On the other hand, the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the method.

[0017] Compared with the prior art, the present invention has the following advantages and technical effects: This invention uses cluster isotope indices as the core criterion. These indices directly reflect the isotopic bonding state within hydrogen molecules, are primarily controlled by formation temperature, and are extremely insensitive to subsequent geological alteration. This fundamentally overcomes the technical deficiency of traditional hydrogen isotope (δD) signals, which are easily reset during migration, and for the first time obtains reliable parameters that are resistant to interference and directly indicate the original formation conditions.

[0018] This invention establishes a closed-loop logical chain from data acquisition to causation determination. Data quality is ensured through sample purification, the originality of the data is guaranteed through cross-validation with multiple pieces of evidence, and the cluster isotope values ​​are quantitatively inverted into formation temperature using theoretical curves. This process transforms causation identification from qualitative speculation to quantitative comparison based on an objective temperature scale, significantly improving the accuracy and repeatability of the determination.

[0019] This invention achieves direct identification of the genetic type by comparing the inversion temperature with a database of preset temperature ranges for different genesis. This method provides a unified and clear criterion for distinguishing the complex and diverse genesis of natural gas, and offers key technical support for the scientific evaluation and efficient exploration of natural hydrogen resources. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the natural hydrogen sample processing procedure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the heating experimental apparatus according to an embodiment of the present invention; Figure 3 This is a graph showing the theoretical relationship between ΔDD and equilibrium temperature in an embodiment of the present invention. Figure 4 This is a graph showing the balance relationship between ΔDD and δD in an embodiment of the present invention. Figure 5 Δ is an embodiment of the present invention. 13 The relationship between CH3D and equilibrium temperature; Figure 6 Δ is an embodiment of the present invention. 12 The relationship between CH2D2 and equilibrium temperature; Figure 7 Δ is an embodiment of the present invention. 13 CH3D and Δ 12 Equilibrium relationship curve of CH2D2; Figure 8 This is a diagram showing the correspondence between the types of natural hydrogen formation and their formation temperatures in an embodiment of the present invention. Figure 9 This is a diagram illustrating the identification of the origin of natural hydrogen based on cluster isotopes, according to an embodiment of the present invention. Figure 10 This is an illustration of the identification of the origin of natural hydrogen based on hydrogen isotopes, according to an embodiment of the present invention. Figure 11 This is a diagram illustrating the hydrogen origin identification based on the methane-hydrogen content relationship and hydrogen isotope composition of hydrogen, according to an embodiment of the present invention. Figure 12 This is a flowchart of a method for identifying the origin type of natural hydrogen based on cluster isotopes, according to an embodiment of the present invention. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0023] Example 1 like Figure 1 As shown, this embodiment provides a method for identifying the origin of natural hydrogen based on cluster isotopes, including the following steps: A purified hydrogen sample to be tested was obtained through separation and purification. Cluster isotope measurements were performed on the purified hydrogen sample to obtain cluster isotope values ​​characterizing the degree to which the abundance of dideuterium molecules deviates from a random distribution. When it is determined that the cluster isotope value is in the original thermodynamic equilibrium state, the formation temperature of the purified hydrogen sample can be deduced based on the theoretical functional relationship between the cluster isotope value and the thermodynamic equilibrium temperature. The formation temperature is compared with the pre-established formation temperature range of natural hydrogen of different origin types to determine the origin type of the purified hydrogen sample.

[0024] As a specific implementation method, the following steps are included: Sample collection and processing: In addition to hydrogen, natural hydrogen gas often contains impurity gases such as methane, nitrogen, and helium. However, isotope mass spectrometers have high requirements for gas purity and must avoid isotope fractionation caused by adsorption-desorption during sample processing as much as possible. Therefore, before performing cluster isotope measurements, low-temperature physical separation using a gas chromatography (GC) system is necessary to effectively remove the aforementioned impurity gases.

[0025] Measuring δD, δDD, and ΔDD values ​​of samples: Addressing the challenges of measuring isotopes in natural hydrogen clusters and the lack of calibration standards for DD, a high-precision, high-resolution isotope mass spectrometer was first used to determine the δD and δDD values ​​of hydrogen samples using the "peak skipping" method. Subsequently, the ΔDD value of the sample was calculated using a ΔDD measurement benchmark method established based on heating equilibrium experiments, combined with corresponding theoretical formulas. Here, δD and δDD values ​​represent the relative abundance of D atoms and DD molecules, respectively. ΔDD refers to the distribution of D atoms in HD and DD molecules, and this parameter is independent of the abundance of D in the sample.

[0026] A theoretical curve function of ΔDD versus the equilibrium temperature of natural hydrogen was established: Combining molecular energy level data obtained from ab initio calculations, fundamental physical constants, and statistical mechanics methods, the thermodynamic equilibrium constants of the isotope exchange reaction of natural hydrogen at different temperatures were calculated, and based on this, a theoretical functional relationship and curve between the ΔDD value and the equilibrium temperature of natural hydrogen were constructed.

[0027] Determining whether the ΔDD of natural hydrogen is in its original thermodynamic equilibrium state: This invention innovatively provides a comprehensive identification method to address the crucial issue of determining whether cluster isotopes in natural hydrogen samples have undergone resetting. This method systematically reviews and integrates the main approaches used in existing technologies to determine whether natural gas samples maintain their original thermodynamic state, ultimately summarizing them into the following four core identification criteria: ① joint analysis based on cluster isotope and hydrogen isotope characteristics; ② direct analysis based on isotope homogenization characteristics; ③ indirect inference based on associated gas component characteristics; ④ comprehensive judgment combining geological background and hydrocarbon accumulation history.

[0028] Establish a quantitative correspondence between different types of natural hydrogen and their formation temperatures: Extensive collection and systematic organization of formation temperature data for natural hydrogen from different origins, derived from existing laboratory simulation studies, will be conducted to construct a quantitative data system corresponding to these two types of hydrogen. Based on this, the formation temperature ranges corresponding to five main causes of natural hydrogen, including water-rock interaction with iron-bearing minerals and microbial hydrogen production, will be summarized.

[0029] Using cluster isotopes to determine the origin of natural hydrogen: The cluster isotope values ​​that can record the original thermodynamic equilibrium state, obtained in the above steps, are imported into the theoretical curve and the recorded formation temperature is derived. By comparing the temperature range of natural hydrogen origin obtained in step five, the origin type of natural hydrogen can be further determined.

[0030] Combining traditional methods for comprehensive identification: In order to further improve the accuracy of identifying the origin of natural hydrogen, based on the preliminary identification of the origin based on cluster isotope values, a multi-dimensional comprehensive analysis can be carried out by combining hydrogen isotope data and the component characteristics of the associated gas in the sample, so as to accurately determine its origin type.

[0031] The feasible process for collecting and processing natural hydrogen samples includes: Natural hydrogen samples were separated and purified using liquid nitrogen cryogenic enrichment. Figure 1 The specific procedure is as follows: ① Remove the gas chromatography (GC) column and fix the 10-20 cm column section near the injection port with metal wire or silicone tubing. Then, place it in a liquid nitrogen cold trap and freeze for 2 minutes to lower the temperature of this column section to approximately -196℃. Continue to maintain the frozen state for 5 minutes to ensure that the cold trap reaches the liquid nitrogen temperature and forms a stable low-temperature zone. ② Draw 10-50 mL of sample and inject it into the 200℃ injection port to vaporize it. Then, pass the sample through the chromatographic column at a constant temperature of 35℃, while adjusting the helium carrier gas flow rate to 1 mL / min to match the instrument's operating requirements. Based on the fact that the relative vapor pressures of methane, nitrogen, and helium are higher than those of hydrogen, all three will be condensed and captured in the low-temperature section. Hydrogen, due to its lower boiling point, remains in a gaseous state and can flow directly out with the carrier gas, thereby achieving the physical purification of hydrogen. ③ Directly introduce the purified hydrogen into a dual-inlet isotope mass spectrometer (IRMS) through the adapter at the end of the chromatographic column for isotope ratio determination.

[0032] An feasible process for measuring and calculating the δD and δDD values ​​of a sample includes: On Earth, hydrogen has two main stable isotopes: protium (¹H) and deuterium (²H or D). Protium is extremely abundant, accounting for approximately 99.984% of hydrogen atoms in natural water bodies; while deuterium is extremely rare, with a natural relative abundance of only 0.0156%. These two isotopes can combine to form different hydrogen molecules, including HH, HD, and DD. Among them, the DD molecule is known as a "cluster isotope" variant, with an extremely low relative abundance of only about 2.4 × 10⁻⁶. ﹣8 Therefore, cluster isotope measurements of natural hydrogen are extremely difficult, and accurate determination is often achieved using a high-resolution, high-sensitivity double-focusing stable isotope mass spectrometer.

[0033] Currently, the most common method for precise measurement of hydrogen cluster isotopes is the Thermo Fisher Scientific MAT253Ultra dual-focusing stable isotope mass spectrometer, which boasts a maximum relative mass resolution of 27,000, sufficient to meet the high-precision measurement requirements of natural hydrogen cluster isotopes. This instrument is equipped with nine detector units, all using Faraday cups. Three miniature ion counters (compact discrete potentiometers, CDDs) are additionally deployed next to the three Faraday cups (H2, H3, and H4) on the high mass-to-charge ratio side of the detector array, while a decelerated potential quadrupole secondary electron multiplier (RPQ-SEM) is installed in the central unit. Furthermore, all units except the central detector are movable, allowing for flexible configuration to adapt to the measurement of different substances. Additionally, the Faraday cups can be fitted with amplifiers of different specifications (3×10⁻⁶) depending on the intensity of the ion beam being measured. 8 Ω, 1×10 9 Ω, 1×10 10 Ω, 1×10 11 Ω, 1×10 12 Ω and 1×10 13 In terms of quality resolution, the instrument supports three quality resolution modes: low, medium, and high. The resolution is determined by the size of the inlet slit (corresponding sizes of 250μm, 16μm, and 5μm, respectively), and the resolution is negatively correlated with the signal strength, that is, the higher the resolution, the lower the signal strength.

[0034] Although the MAT253Ultra dual-focusing stable isotope mass spectrometer possesses sufficient accuracy in determining cluster isotope pairs of natural hydrogen, it is limited by the significant mass differences among the HH, HD, and DD ion beams, resulting in dispersions of up to 15%, exceeding the effective range of the instrument's collection plane. Therefore, simultaneous measurement of the three ion beams cannot be achieved under normal conditions. To address this issue, a "peak-skipping" measurement method can be employed. The core idea of ​​this method is to sequentially determine different isotopic isomers within a single acquisition cycle. It uses a five-cycle sequence design of A—B—A—B—A (where A is the reference gas and B is the sample gas), and this sequence needs to be repeated 5-7 times for a single complete measurement. Simultaneously, before initiating each measurement sequence, pressure adjustment is required to re-equilibrate the HH⁺ signal intensity of the sample and reference gases. Specifically, within a single acquisition cycle, the measurement process follows a fixed time sequence: ① First, the HH ion beam is integrated 10 times (each integration lasts 0.13 seconds); ② Then, the HD ion beam is integrated 20 times (each integration lasts 1 second); ③ Finally, the DD ion beam is integrated 20 times (each integration lasts 8 seconds).

[0035] In addition, a brief "virtual" measurement sequence is required before formally integrating the DD ion beam to stabilize the ion counter (CDD). To further eliminate interference and investigate potential memory effects during gas switching, the HD / HH ratio of the corresponding gas must be measured synchronously before and after each DD ion beam measurement. After all measurements are completed, background signals (typically below 1000 cps for HD and approximately 0.02–0.2 cps for DD) are collected approximately 0.0020 Da to the left of the HD and DD peaks, and this background signal is subtracted from the measured signal of the sample.

[0036] Finally, based on the measured HD / HH and DD / HH ratios, the δD and δDD values ​​of the sample relative to the reference gas can be calculated by substituting them into the corresponding formulas, as shown in equations (1) and (2).

[0037] (1) (2) The feasible process for calculating the ΔDD value of a sample and its relationship with the equilibrium temperature includes: The ΔDD value refers to the degree to which the measured abundance ratio of dideuterium (DD) molecules to ordinary hydrogen (HH) molecules in hydrogen deviates from a random distribution. It can quantitatively characterize the enrichment or depletion level of DD molecules in nature compared to a random distribution. Theoretically, ΔDD can be directly calculated from the abundance of three isotopes: HH, HD, and DD, as shown in Equation (3). However, this calculation depends on the absolute abundance of each isotope, and there is currently a lack of calibration standards for DD. In addition, in actual measurements, factors such as the nonlinear response of the instrument and the fact that the DD / HH ratio of the working gas itself may have deviated significantly from a random distribution can also affect the accurate acquisition of ΔDD, making the directly calculated ΔDD only a relative value with bias.

[0038] Therefore, regarding the determination of isotope values ​​of natural hydrogen clusters, this invention, through a comprehensive review of previous research methods, ultimately selected and established the optimal method. This method directly measures ΔDD using a heating equilibrium experiment, establishing a baseline method for ΔDD measurement. The calculated ΔDD does not require conversion to the VSMOW scale, and its standard error directly represents the measurement accuracy. The specific operation is as follows (…). Figure 2① First, the heating tube is evacuated. Then, purified hydrogen is injected into a quartz tube containing a platinum catalyst and brought to a specific pressure (absolute pressure range 400-1000 mbar). This pressure value needs to be adjusted according to the thermal expansion coefficient of the preset heating temperature. ② It is heated continuously at 850℃ (the highest experimental temperature) for about 8 hours to allow it to reach thermodynamic isotope equilibrium at that temperature. ③ Then, the test tube clamp is opened to allow the hydrogen to expand directly and be introduced into the mass spectrometer for measurement. To verify whether the gas has reached complete equilibrium, this study uses the gas after equilibrium at 850℃ as a calibration reference. The theoretical ΔDD value corresponding to this temperature is calculated to be approximately 19‰ based on the molecular mass and internal partition function. Based on this, the ΔDDref of the reference gas is specified as 19‰. ④ The ΔDD value of the sample to be tested can be calculated using the corresponding formula, as shown in equation (4).

[0039] (3) (4) In fitting studies of the temperature curves of natural hydrogen cluster isotopes and thermodynamic equilibrium states, if the ΔDD value is directly calculated from the abundances of the three isotopes HH, HD, and DD, the original measured values ​​must first be calibrated and converted into comparable ΔDD_ARF calibration values ​​before they can be used to invert the formation temperature of hydrogen in thermodynamic equilibrium. However, if the ΔDD_sam value is obtained by measuring the ΔDD measurement benchmark method established based on the heating equilibrium experiment, it can be directly used for temperature inversion. Based on this experimental method, the construction process of the cluster isotope and thermodynamic equilibrium temperature curve function is as follows: ① First, the Schrödinger equations of hydrogen molecules (H2), deuterium molecules (D2 or DD), and hydrogen-deuterium molecules (HD) are accurately solved using the abinitio quantum chemical calculation method to obtain the energy level data of each molecule; ② Based on the energy level data, the internal partition function of each molecule (HH, HD, DD) at temperature T is calculated; ③ Based on the natural hydrogen isotope exchange reaction, see equation (5), the ratio of the partition function of the isotope exchange reaction at different temperatures (thermodynamic equilibrium constant) is obtained; ④ The calculated thermodynamic equilibrium constant is converted into the expression function of ΔDD ( Figure 3 ), see equation (6).

[0040] (5) (6) An feasible process for determining whether the ΔDD value of a natural hydrogen sample is in its original thermodynamic equilibrium state includes: The most direct way to determine whether the cluster isotope composition of natural hydrogen has reached thermodynamic equilibrium is to check whether its cluster isotope values ​​fall on the thermodynamic equilibrium curve of cluster isotope value versus temperature. If the measured data lies on this calculated equilibrium curve, it indicates that the natural hydrogen either reached thermodynamic equilibrium at the time of its formation or underwent thermodynamic reequilibrium later and eventually settled at this equilibrium state.

[0041] Whether cluster isotope data of natural hydrogen has undergone a subsequent thermodynamic rebalancing is a crucial prerequisite for its effective indication of original geological processes. Determining whether cluster isotopes of natural hydrogen have undergone a subsequent thermodynamic rebalancing is complex and cannot rely on a single observational indicator; it requires comprehensive constraints based on multiple pieces of evidence from geology, geochemistry, and isotope dynamics. Currently, there is no systematic research on whether the cluster isotope values ​​(ΔDD) of natural hydrogen have undergone a subsequent thermodynamic rebalancing. However, research on cluster isotopes in natural gas is relatively mature, and methods for determining whether cluster isotopes in natural gas have undergone a subsequent thermodynamic rebalancing can be used to establish a similar discrimination scheme for natural hydrogen. However, these identification results also have significant ambiguity; therefore, they cannot be determined based on a single piece of evidence but require discussion and integration of multiple pieces of evidence. Among these, four common identification methods are: ① When performing joint analysis based on cluster isotope (ΔDD) and hydrogen isotope (δD) characteristics, if the sample measurement value is located on the ΔDD-δD theoretical equilibrium curve or within its error tolerance range (e.g.) Figure 4 The area within the dashed line indicates that the sample currently exhibits an isotopic equilibrium state, and its isotopic signal may well preserve the equilibrium information from its original formation. However, this phenomenon could also be caused by intense subsequent geological or geochemical processes, meaning that the cluster isotopes and hydrogen isotopes of the sample were completely reset during later processes, reaching a new equilibrium. Therefore, the consistency of the two isotopic parameters alone is insufficient to uniquely determine its genetic attribute. A systematic and comprehensive assessment must be conducted, combining the characteristics of associated gas components and the reservoir geological background (such as lithology, tectonic history, and fluid activity history), to accurately distinguish between the two scenarios of "original equilibrium" and "later reset."

[0042] ② Determining whether isotopic repositioning of natural hydrogen clusters based on isotopic homogenization characteristics is a crucial method for analyzing their origin and evolution. If, within the same geological unit, natural gas hydrogen samples collected from different locations and depths show significant consistency in their δD and ΔDD values, it often indicates that these gases have undergone uniform post-modification processes, and their original isotopic composition may have been repositioned or homogenized. According to industry standards, when using a high-precision mass spectrometer in the laboratory, if the measurement accuracy of δD is better than ±1‰ and the measurement accuracy of ΔDD falls between 2 and 6‰, it can be considered to meet the measurement error requirements. Therefore, under these conditions, if the hydrogen isotope and cluster isotope measurements of different samples within the same reservoir are within the aforementioned error range, we can reasonably assume that their isotopic composition is consistent in analysis, and thus infer that the gas may have undergone isotopic homogenization. However, this situation could also be due to these gases originating from a common source or reservoir. Therefore, it is necessary to conduct a comprehensive assessment in conjunction with other regional geochemical indicators and hydrogeological information.

[0043] ③ Inferring whether the isotopes of natural hydrogen have undergone late reset by using the characteristics of associated gases. Samples collected from natural hydrogen reservoirs are not composed of a single hydrogen component; they are usually accompanied by gases such as methane and helium. If it can be determined that the associated gases are of the same origin as the natural hydrogen, it is possible to infer whether the isotopes of the natural hydrogen clusters have undergone late reset by measuring the geochemical indicators of the associated gases. Taking the associated helium of natural hydrogen as an example, its genetic type can be classified by its isotopic composition, specifically into three categories: atmospheric, crustal, and mantle-derived. Helium isotope characteristics are commonly represented by the R / Ra value: where R represents the 3He / 4He ratio of the sample, and Ra is the 3He / 4He value in the atmosphere, which is constant at 1.4 × 10⁻⁶. −6 The criteria for determining this ratio are as follows (Table 1): When the R / Ra value is less than 0.1, the helium is primarily of shell origin; when the R / Ra value is greater than 0.1, the proportion of mantle-derived helium exceeds 1.2%, but the overall origin is still predominantly shell-derived; when the R / Ra value is greater than 1, the proportion of mantle-derived helium exceeds 12%, and the origin is predominantly mantle-derived. Based on this, the genetic attribution of associated helium can be used to determine whether the source of natural hydrogen is deep or shallow, and then, combined with temperature data indicated by cluster isotopes, a comprehensive analysis can be conducted.

[0044]

[0045] Taking associated methane gas as an example, previous research has extensively investigated whether isotopes in methane clusters have undergone reequilibrium. Previous studies have shown that although there are kinetic isotope effects related to the later irreversible hydrogenation steps during methane molecule formation, 13 The CH3D bond order is still primarily determined by the synthesis temperature. Assuming large-scale gas mixing or degradation occurs, Δ can be directly utilized. 13The CH3D value defines the approximate formation temperature of inorganic methanes in the Fischer-Tropsch synthesis (e.g., Figure 5 If the methane gas and natural hydrogen gas share the same origin, comparing the aforementioned temperatures with the temperatures indicated by the isotopes of natural hydrogen clusters can provide a basis for determining whether a reequilibrium has occurred in the natural hydrogen cluster isotopes. Meanwhile, some scholars have also pointed out that Δ... 12 CH2D2 is extremely sensitive to the combination effect of hydrogen atoms during methane formation, and the experimental product's Δ 12 CH2D2 values ​​generally exhibit significant non-equilibrium characteristics (e.g., Figure 6 In comparison, Δ 13 CH3D is primarily temperature-controlled and insensitive to combination effects, making it an effective isotope thermometer. Based on this, they constructed a Δ... 13 CH3D and Δ 12 The coupling discriminant relationship of CH2D2 is used to comprehensively determine whether a reequilibrium has occurred in a methane cluster isotope system (e.g., Figure 7 If Δ 13 The CH3D value is close to the thermodynamic equilibrium state (indicating the formation temperature), while Δ 12 A significant depletion of the CH2D2 value indicates that methane retains the kinetic fractionation signal from its initial formation stage. This non-equilibrium combination characteristic is considered a pristine property of inorganic methane synthesized via the Fischer-Tropsch synthesis, implying that its isotopic system has not undergone a later reset. Conversely, if both values ​​fall consistently on the thermodynamic equilibrium curve at the corresponding temperature, it indicates that the methane isotopic system has undergone a later reset, reaching a new thermodynamic equilibrium state. Using this approach, analyzing the cluster isotopic equilibrium state of associated methane gas can also provide a more reliable basis for inferring whether the cluster isotopes of natural hydrogen have undergone a later reset.

[0046] ④ Conduct comprehensive analysis in conjunction with the regional geological background. Firstly, research should be conducted directly on reservoir temperature. If the measured ΔDD value in the laboratory precisely corresponds to the current geothermal temperature of the reservoir, two possibilities exist. The first is that the hydrogen cluster isotope system has reached a new thermodynamic equilibrium with the current environment over a long geological history, and the original reservoir formation information has been completely lost. The second is that the formation temperature of hydrogen itself is consistent with the current geothermal temperature of the reservoir. Secondly, research can be conducted in conjunction with regional geological activity. For example, a comprehensive analysis can be performed by assessing whether paleohydrothermal activity occurred in the study area. If hydrothermal activity occurred in the study area, and the temperature indicated by the natural hydrogen cluster isotopes highly matches the temperature during the paleohydrothermal activity period, the probability that the natural hydrogen cluster isotope system underwent a later reequilibrium process will be significantly increased.

[0047] A feasible process for establishing a correspondence between the types of natural hydrogen formation and their formation temperatures, and thereby identifying the mechanisms of natural hydrogen formation, includes: The formation temperatures of natural hydrogen vary significantly depending on its origin. To define the quantitative relationship between different types of natural hydrogen origin and their formation temperatures, it is first necessary to extensively collect and systematically organize the formation temperature data of natural hydrogen from different origins based on existing laboratory simulation studies, and then construct a corresponding quantitative data system. Overall, the main formation temperatures corresponding to the following types of natural hydrogen origin can be summarized as follows (…). Figure 8 (Table 2): ① The natural hydrogen formation temperature corresponding to microbial hydrogen production is 15℃~85℃; ② The natural hydrogen formation temperature corresponding to organic matter thermal evolution hydrogen production is 120℃~350℃; ③ The natural hydrogen formation temperature corresponding to water-rock reaction hydrogen production of iron-bearing minerals (including serpentinization) is 50℃~500℃; ④ Radioactive hydrogen production of water is only related to the radioactive dose and the chemical properties of water, and can form under different temperature conditions; ⑤ The natural hydrogen formation temperature corresponding to water free radical decomposition hydrogen production related to rock fragmentation is 25℃~400℃. Based on the above steps, the ΔDD value of the hydrogen sample in the original thermodynamic equilibrium state is accurately measured, and this value is substituted into the cluster isotope dependence curve of equilibrium temperature ( Figure 3 This allows for the inversion of the temperature environment parameters during sample formation. Subsequently, a systematic comparison of these temperature parameters with the formation temperature ranges of various natural hydrogen gases can further pinpoint the possible formation type of the sample, thus aiding in the further deduction of its complete formation mechanism. Figure 9 ).

[0048]

[0049] An feasible process for comprehensive identification combining traditional identification methods includes the following steps: While using cluster isotopes (ΔDD) for identification offers significant advantages over traditional methods for determining the origin of natural hydrogen, the temperature ranges corresponding to ΔDD are typically wide and overlapping. When the inversion temperature falls within this overlapping range, it can lead to multiple interpretations of the origin. For example, when ΔDD indicates a temperature of approximately 450°C, its origin could correspond to either radiolysis of water or a water-rock reaction involving iron-bearing minerals. Therefore, to accurately determine the genetic mechanism of natural hydrogen, further integration of hydrogen isotopes (ΔDD) is necessary after initial identification based on cluster isotopes. Figure 10 ) and associated gas component data ( Figure 11 ), and conduct multi-dimensional comprehensive analysis to accurately identify its cause type ( Figure 12 For example, in this case, if the measured hydrogen isotope value of the sample is -650‰ and the associated gas characteristics indicate that it is of crustal origin, then it can be clearly determined that the natural hydrogen gas originates from the water-rock reaction of iron-bearing minerals.

[0050] Current technologies primarily rely on hydrogen isotope (δD) and associated gas component analysis. The former, due to the reactive nature of hydrogen, readily exchanges isotopes with the surrounding environment during transport and storage, severely altering or even resetting the original causal signal. The latter, however, is indirect evidence, offering multiple interpretations and failing to uniquely and accurately correspond to the complex and diverse causal types. These shortcomings limit the reliability and accuracy of the identification results.

[0051] This embodiment fundamentally changes this situation by using cluster isotopes (ΔDD) as the core indicator. Cluster isotopes record the abundance of heavy isotopic bonding within hydrogen molecules, and their values ​​are mainly controlled by the temperature at formation, exhibiting strong "inertness" to processes such as fluid migration and subsequent water-rock interactions. Therefore, this method first solves the key problem of signal anti-interference, effectively acquiring and retaining the temperature information at the initial formation or final thermal equilibrium of hydrogen, avoiding the drawback of traditional hydrogen isotopes being easily "reset".

[0052] Building upon this foundation, this embodiment constructs a complete logical chain from sample processing, high-precision measurement, equilibrium state identification to temperature inversion and genetic comparison. By cross-validating multiple pieces of evidence (such as combining δD, associated gas characteristics, and geological background), it is determined whether the ΔDD value represents the original equilibrium state, ensuring the "purity" and validity of the temperature signal used for inversion. Subsequently, the inverted temperature is compared with a database of temperature ranges corresponding to different genetic types established through systematic research, achieving a leap from qualitative inference to quantitative discrimination. This provides a clear and objective temperature benchmark for distinguishing different genetic origins such as microbial hydrogen production, water-rock reaction, and organic matter pyrolysis.

[0053] Ultimately, the technical effects of this embodiment are reflected in three aspects: First, it provides a direct and robust causal identification index (based on temperature ΔDD), significantly improving the objectivity and accuracy of the identification results; second, it forms an anti-interference, closed-loop comprehensive analysis process, reducing the risk of misjudgment due to later modifications or single evidence; third, through the organic combination with traditional δD and associated gas component data, it achieves multi-dimensional information complementarity and cross-validation, further enhancing the ability to identify complex causes and the reliability of conclusions, providing more solid scientific support for the resource evaluation and exploration decision-making of natural hydrogen.

[0054] On the other hand, the present invention also provides a computer device including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method.

[0055] On the other hand, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method.

[0056] On the other hand, the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the method.

[0057] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for identifying the origin of natural hydrogen based on cluster isotopes, characterized in that, Includes the following steps: A purified hydrogen sample to be tested was obtained through separation and purification. Cluster isotope measurements were performed on the purified hydrogen sample to obtain cluster isotope values ​​characterizing the degree to which the abundance of dideuterium molecules deviates from a random distribution. When it is determined that the cluster isotope value is in the original thermodynamic equilibrium state, the formation temperature of the purified hydrogen sample can be deduced based on the theoretical functional relationship between the cluster isotope value and the thermodynamic equilibrium temperature. The formation temperature is compared with the pre-established formation temperature range of natural hydrogen of different origin types to determine the origin type of the purified hydrogen sample.

2. The method for identifying the origin of natural hydrogen based on cluster isotopes according to claim 1, characterized in that, The purified hydrogen sample to be tested is obtained through separation and purification processes, specifically including: A liquid nitrogen cryogenic enrichment method is used to process natural hydrogen samples containing impurities. By utilizing the difference in boiling points between hydrogen and impurity gases, the impurity gases are condensed and retained under low-temperature conditions, thereby keeping the hydrogen components in a gaseous state and allowing them to flow out through a carrier gas, thus achieving the physical separation and purification of hydrogen. The impurity gases include methane, nitrogen, and helium.

3. The method for identifying the origin of natural hydrogen based on cluster isotopes according to claim 1, characterized in that, Cluster isotope measurements were performed on the purified hydrogen sample to obtain cluster isotope values ​​characterizing the degree to which the abundance of its dideuterium molecules deviates from a random distribution. Specifically, this included: Using a high-resolution stable isotope mass spectrometer, the signal intensities of the ordinary hydrogen molecular ion beam, hydrogen deuterium molecular ion beam, and double deuterium molecular ion beam in the purified hydrogen sample were measured sequentially using the peak skipping method, and the background signal was subtracted. The hydrogen isotope δD value of the sample was calculated based on the measured signal intensity ratio between hydrogen deuterium molecules and ordinary hydrogen molecules. Based on the measured signal intensity ratio between the dideuterium molecule and the ordinary hydrogen molecule, the δDD value of the dideuterium molecule in the sample was calculated. Based on the benchmark measurement method established by the heating equilibrium experiment, the cluster isotope ΔDD value of the purified hydrogen sample is calculated using a reference gas that has undergone high-temperature thermodynamic equilibrium treatment.

4. The method for identifying the origin of natural hydrogen based on cluster isotopes according to claim 1, characterized in that, Determining whether the cluster isotope values ​​of the purified hydrogen sample are in a state of original thermodynamic equilibrium specifically includes comprehensive identification using at least one of the following methods: Based on the joint analysis of cluster isotope values ​​and hydrogen isotope values, it is determined whether they are within the theoretical equilibrium relationship curve or its error range. Based on the consistency characteristics of hydrogen isotope values ​​and cluster isotope values ​​of different samples within the same geological unit, it can be determined whether they have undergone an isotope homogenization process. Indirect inferences can be made based on the geochemical characteristics of associated gases, including determining the gas source depth by the helium isotope ratio of associated helium, or inferring whether hydrogen has undergone a later reset by analyzing the cluster isotope balance of associated methane. By combining regional geological background and reservoir temperature information, a comprehensive analysis is conducted to determine whether the temperature indicated by cluster isotopes matches the current geothermal temperature or the temperature of ancient hydrothermal activity in the reservoir.

5. The method for identifying the origin of natural hydrogen based on cluster isotopes according to claim 1, characterized in that, Based on the theoretical functional relationship between cluster isotope values ​​and thermodynamic equilibrium temperature, the formation temperature of the purified hydrogen sample can be deduced, specifically including: The theoretical functional relationship is established in advance by obtaining energy level data of hydrogen molecules, deuterium molecules, and hydrogen-deuterium molecules through quantum chemical calculations, calculating the thermodynamic equilibrium constant of isotope exchange reactions at different temperatures, and converting the equilibrium constant into a functional relationship between cluster isotope values ​​and temperature.

6. The method for identifying the origin of natural hydrogen based on cluster isotopes according to claim 1, characterized in that, The pre-established temperature ranges for the formation of natural hydrogen from different genetic types include: the temperature range corresponding to hydrogen production by microorganisms, the temperature range corresponding to hydrogen production by the thermal evolution of organic matter, the temperature range corresponding to hydrogen production by the water-rock reaction of iron-bearing minerals, the temperature conditions corresponding to hydrogen production by the radiation decomposition of water, and the temperature range corresponding to hydrogen production by the decomposition of water free radicals related to rock fragmentation.

7. The method for identifying the origin of natural hydrogen based on cluster isotopes according to claim 1, characterized in that, After determining the preliminary origin type of the purified hydrogen sample, a multi-dimensional comprehensive analysis is conducted by combining the hydrogen isotope data of the purified hydrogen sample and the component characteristics of its associated gas to ultimately pinpoint its origin type.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1-7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the method according to any one of claims 1-7.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the method according to any one of claims 1-7.

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