Method for obtaining hydrogen fugacity in sedimentary organic matter

Abstract

The invention provides a method for acquiring hydrogen fugacity in sedimentary organic matters, which can calculate the hydrogen fugacity in the sedimentary organic matters according to organic chemical analysis results of sedimentary organic matter matrixes in natural geological samples, artificial cured samples and chemical refining samples and temperature conditions of a system. In geological evolution, artificial curing and crude oil refining, the hydrogen fugacity of the sedimentary organic matter is one of important parameters for controlling oil gas generation, so that the method for evaluating the hydrogen fugacity of the sedimentary organic matter can provide a new reference basis for understanding an organic matter hydrocarbon generation process mechanism and evaluating resource potential.

Description

Technical Field

[0001] The invention relates to the field of geochemical technology, and in particular to a method for obtaining hydrogen fugacity in sedimentary organic matter. Background Art

[0002] Organic-rich sedimentary rocks (such as shale, coal seams, etc.) will generate hydrogen-rich mobile phase oil and gas components and carbon-rich solid phase condensation products after natural or artificial thermal action. In this process, the hydrogen in the organic matter can come from the organic matter itself or from exogenous inorganic hydrogen. In deep and ultra-deep layers with great burial depth, high temperature and high pressure, water-rock interaction can maintain the hydrogen fugacity of deep formations at a higher level than that of medium and shallow layers, which also makes it possible for hydrogen from inorganic sources to be added to organic matter for hydrocarbon generation. Since the essence of thermal evolution of organic matter is a disproportionation reaction accompanied by hydrogen transfer, hydrogen fugacity has an important influence on the hydrocarbon production effect of hydrocarbon-generating parent materials. Whether it is the geological evolution of source rocks, artificial maturation, or crude oil refining, hydrogen fugacity in organic matter is one of the important parameters affecting oil and gas generation. Effective evaluation of hydrogen fugacity in organic matter is the key to systematically clarifying the hydrocarbon generation process and mechanism. For example, in the field of deep-earth resource exploration, paying attention to the hydrogen fugacity level in organic matter not only has important guiding value for studying the resource effects of organic-inorganic composite hydrocarbon generation, but may also provide key clues for the future exploration of clean energy such as natural hydrogen.

[0003] At present, there are few descriptions of the redox state of sedimentary organic matter during thermal evolution. Under certain temperature and pressure conditions, the hydrogen fugacity of organic matter in deep geological bodies can reflect the redox state of the system to a certain extent. The promoting effect of deep hydrogen-rich fluids on hydrocarbon generation from organic matter also means that the hydrogen fugacity of the system is significantly increased. In addition, many traces of natural hydrogen have also been found during deep drilling. The above phenomenon can qualitatively determine the relative level of hydrogen fugacity in sedimentary organic matter, but it cannot be quantitative. Summary of the invention

[0004] The present invention provides a method for obtaining hydrogen fugacity in sedimentary organic matter, which can realize the calculation of hydrogen fugacity in sedimentary organic matter according to the organic chemical analysis results in the sedimentary organic matter and the temperature conditions of the system, and can provide key parameters for systematically clarifying the hydrocarbon generation process and mechanism.

[0005] The present invention provides a method for obtaining the hydrogen fugacity of a system in sedimentary organic matter, comprising the following steps:

[0006] Obtain the olefin-alkane activity ratio of target hydrocarbons in sedimentary organic matter;

[0007] The hydrogen fugacity is obtained based on the olefin activity ratio, the Gibbs free energy change of olefin conversion and the system temperature of the deposited organic matter.

[0008] The acquisition method as described above, wherein the hydrogen fugacity is acquired according to the olefin activity ratio, the olefin conversion Gibbs free energy change and the system temperature of the deposited organic matter, comprises: calculating the hydrogen fugacity according to Formula 1:

[0009]

[0010] Among them, f H2 is hydrogen fugacity, bar; ΔrGm is Gibbs free energy change for olefin conversion, J / mol; R is gas constant, 8.314 J / (mol·K); T is absolute temperature of the system where organic matter is deposited, K; α 烯烃 / α 烷烃 is the olefin activity ratio.

[0011] The acquisition method as described above, wherein the olefin activity ratio of the target hydrocarbon in the sedimentary organic matter is obtained, comprises the following steps:

[0012] Obtaining the matrix of inclusions in sedimentary organic matter;

[0013] Separating and treating the encapsulated matrix to obtain encapsulated hydrocarbons;

[0014] The encapsulated hydrocarbons are detected by gas chromatography-mass spectrometry to obtain the olefin-alkane activity ratio of the olefin target hydrocarbons;

[0015] The mass percentage of the encapsulated hydrocarbon in the encapsulated matrix is ​​not less than 0.002%.

[0016] The acquisition method as described above, wherein the separation process comprises:

[0017] Step 1, fully dissolving the encapsulation matrix in an organic solvent to obtain a dilute solution of the encapsulation matrix;

[0018] Step 2, uniformly dispersing the activated silica gel particles in an organic solvent to obtain a silica gel suspension; wherein the organic solvent in step 2 is the same as the organic solvent in step 1; the organic solvent is at least one of dichloromethane, chloroform, benzene, toluene, tetrahydrofuran, ethyl acetate, carbon disulfide, and nitrogen methyl pyrrolidone;

[0019] Step 3, under stirring conditions, dropwise add the encapsulation matrix dilute solution into the silica gel suspension, until all the encapsulation matrix dilute solution is added into the silica gel suspension, continue stirring and then stand until the silica gel particles are completely precipitated;

[0020] Step 4: filtering the system obtained in step 3 to separate the liquid and the solid silica gel particles; rotary evaporating the liquid, and separating the concentrated liquid obtained by rotary evaporation by column chromatography to obtain encapsulated hydrocarbons.

[0021] The acquisition method as described above, wherein, in the gas chromatography-mass spectrometry detection, the detection conditions of the gas chromatography include a helium flow rate of 1 mL / min and a column box temperature program; the detection conditions of the mass spectrometry include a scanning range of m / z 50-450;

[0022] The column oven temperature program included holding at 50°C for 1 minute, then heating to 100°C at a rate of 20°C / min and holding for 1 minute, and finally heating to 310°C at a rate of 3°C / min and holding for 20 minutes.

[0023] In the acquisition method as described above, the target hydrocarbons are normal hydrocarbons.

[0024] In the acquisition method as described above, the olefin conversion energy barrier of the target hydrocarbon is not higher than 481160 J / mol.

[0025] The acquisition method as described above, wherein the target hydrocarbon is C 16 Hydrocarbon or C 18 hydrocarbon.

[0026] The acquisition method as described above, wherein the package matrix includes at least one of asphaltene, kerogen, and solid asphalt.

[0027] In the acquisition method as described above, the sedimentary organic matrix includes at least one of organic matter in natural geological samples, artificially matured samples, and solid residues after chemical refining.

[0028] The present invention provides a method for obtaining hydrogen fugacity in sedimentary organic matter, which can be used to infer hydrogen fugacity in sedimentary organic matter based on target hydrocarbons in natural geological samples, artificially matured samples or solid residues after chemical refining. Since hydrogen fugacity in sedimentary organic matter is one of the important parameters controlling oil and gas generation in geological evolution, artificial maturation and crude oil refining, evaluating hydrogen fugacity in sedimentary organic matter by the method of the present invention can provide a new reference for understanding the mechanism of organic matter hydrocarbon generation process and resource potential. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific implementation methods listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0030] The present invention provides a method for obtaining hydrogen fugacity in sedimentary organic matter, comprising the following steps:

[0031] Obtain the olefin-alkane activity ratio of target hydrocarbons in sedimentary organic matter;

[0032] The hydrogen fugacity is obtained based on the olefin activity ratio, the Gibbs free energy change of olefin conversion and the system temperature of the deposited organic matter.

[0033] Sedimentary organic matter refers to natural organic matter that was deposited into rocks along with inorganic matter during the geological history, and the products derived from them during the geological evolution process and after being mined and processed by humans. Sedimentary organic matter contains macromolecular matrices, such as asphaltene, which can be called sedimentary organic matter matrix or encapsulation matrix.

[0034] The hydrogen fugacity of the present invention refers to the effective hydrogen partial pressure in the deposited organic matrix, which is equal to the pressure of ideal hydrogen gas with the same chemical potential under the same conditions. It is understandable that the hydrogen fugacity obtained in the present invention is the hydrogen fugacity in the macromolecular matrix.

[0035] Generally, the sedimentary organic matter contains hydrocarbon organics such as alkanes, olefins and aromatic hydrocarbons. Since the conversion between olefins and alkanes is easier to occur, and olefins and alkanes are more likely to be well preserved in the macromolecular matrix structure in the sedimentary organic matter, the present invention takes the mutual conversion between olefins and alkanes as the entry point, and uses the conversion behavior of hydrogenation and dehydrogenation of the two as the source of hydrogen fugacity. Of course, the conversion between olefins and alkanes refers to the conversion of olefins and alkanes with the same carbon atoms.

[0036] In detail, after obtaining the deposited organic matter, it is necessary to first determine that there are olefins and alkanes with the same number of carbon atoms, and use them as the acquisition object of hydrogen fugacity, i.e., the target hydrocarbon of the present invention. Subsequently, according to the olefin activity ratio, the olefin conversion Gibbs free energy change and the system temperature of the deposited organic matter, the hydrogen fugacity is obtained. Due to the conversion of olefins and alkanes, it is also related to the olefin conversion Gibbs free energy change and the system temperature of the deposited organic matter, therefore, the present invention is based on the olefins and alkanes in the deposited organic matter as objects, by the olefin activity ratio in the deposited organic matter, the olefin conversion Gibbs free energy change (the Gibbs free energy change of olefin to alkane conversion) and the system temperature of the deposited organic matter, finally obtain the hydrogen fugacity with more reference and reference value, complete the qualitative-semi-quantitative analysis of the hydrogen fugacity of the deposited organic matter.

[0037] The Gibbs free energy change of the olefin conversion of the target hydrocarbon under certain temperature conditions is obtained by constructing and optimizing the molecular models of the reactants and products using Gaussian software. For example, in one embodiment of the present invention, the target hydrocarbon is C 16 Hydrocarbon or C 18 The Gibbs free energy changes for the conversion of hydrocarbons to alkenes are shown in Table 1.

[0038] Table 1

[0039]

[0040]

[0041] The present invention does not limit the method for obtaining the system temperature of the deposited organic matter, for example, it can be a thermocouple method, temperature measurement of the matrix, apatite fission track analysis, Barker temperature function method, EASY%Ro simulation and other methods.

[0042] It is understood that the system temperature of the deposited organic matter refers to the temperature of the stratum or experimental device where the deposited organic matter is located. For example, when the deposited organic matter is organic matter in a natural geological sample, the system temperature refers to the stratum temperature where the natural geological sample is located; when the deposited organic matter is an artificially matured sample or a solid residue after chemical refining, the system temperature refers to the experimental system temperature where the artificially matured sample or the solid residue after chemical refining is located, that is, the system temperature during the thermal simulation experiment.

[0043] In the scheme of the present invention, obtaining the hydrogen fugacity of sedimentary organic matter can provide a new reference for understanding the mechanism of organic matter hydrocarbon generation process and resource potential. Since the present invention calculates the hydrogen fugacity in sedimentary organic matter based on the organic chemical analysis results of sedimentary organic matter and the temperature conditions of the system, the present invention is not only suitable for obtaining the hydrogen fugacity of the experimental system in the artificial thermal simulation experiment, but also suitable for the hydrogen fugacity of organic matter in the actual geological strata, which can reflect a more realistic hydrocarbon generation process and mechanism.

[0044] Further, according to the olefin activity ratio, the Gibbs free energy change of olefin conversion and the system temperature of the deposited organic matter, the hydrogen fugacity is obtained, including: calculating the hydrogen fugacity according to formula 1:

[0045]

[0046] Among them, f H2 is hydrogen fugacity, bar; ΔrGm is the Gibbs free energy change for olefin conversion, J / mol; R is the gas constant, 8.314 J / (mol·K); T is the absolute temperature of the stratum where organic matter is deposited, K; α 烯烃 / α 烷烃 is the olefin activity ratio.

[0047] In a specific embodiment, obtaining the olefin activity ratio of the target hydrocarbon in the sedimentary organic matter comprises the following steps:

[0048] Obtaining the matrix of inclusions in sedimentary organic matter;

[0049] Separating and treating the encapsulated matrix to obtain encapsulated hydrocarbons;

[0050] The encapsulated hydrocarbons are detected by gas chromatography-mass spectrometry to obtain the olefin activity ratio of the target hydrocarbons;

[0051] The mass percentage of the encapsulated hydrocarbon in the encapsulated matrix is ​​not less than 0.002%.

[0052] Some typical organic geological macromolecules have natural confined spaces inside their molecular structures, which encapsulate and protect a series of active small molecules, such as olefin compounds, which have a certain indicative significance for the chemical environment of the corresponding strata. Among them, the encapsulation matrix refers to the organic geological macromolecules that encapsulate alkane and olefin molecules in a structure mainly composed of liquid or solid organic matter, that is, the sedimentary organic matrix.

[0053] The present invention does not limit the specific method of obtaining the inclusion matrix in the sedimentary organic matter. For example, in one embodiment of the present invention, the inclusion matrix in the sedimentary organic matter, i.e., asphaltene, can be obtained in accordance with the Chinese petroleum and natural gas industry standards: SY / T 5118-2021 Determination of extract content in rocks and SY / T 5119-2016 Analysis of soluble organic matter and crude oil group components in rocks.

[0054] After the obtained encapsulated matrix is ​​further separated, the hydrocarbon compounds encapsulated and protected in the encapsulated matrix, namely, encapsulated hydrocarbons, can be obtained.

[0055] By using gas chromatography-mass spectrometry to detect the encapsulated hydrocarbons, the olefin activity ratio of the target hydrocarbons in the encapsulated hydrocarbons can be obtained. Among them, chromatography is a fast and efficient separation technology, but it cannot identify each separated component; while mass spectrometry is an important method for qualitative identification and structural analysis, a highly sensitive and efficient qualitative analysis tool, but it has no separation ability and cannot directly analyze mixtures. Therefore, the chromatography-mass spectrometry technology combines the two and uses the mass spectrometer as the detector of the chromatograph. It can give full play to the advantages of both, with the high resolution of chromatography and the high sensitivity of mass spectrometry, and is an effective tool for qualitative and quantitative analysis of organic compounds.

[0056] According to the total ion current diagram obtained by gas chromatography-mass spectrometry, the compound peak area ratio of olefins and alkanes of the target hydrocarbon can replace the olefin-alkanes activity ratio of the target hydrocarbon, because the peak area of ​​the compound in the total ion current diagram detected by gas chromatography-mass spectrometry is proportional to the content of the compound, especially the peak area ratio of normal chain hydrocarbons with the same carbon number can replace its content ratio. The content ratio refers to the ratio of the amount of a component in a mixed system to the total amount of the mixed system, while the activity ratio describes the ratio of the ability of each component to actually participate in the reaction in a chemical reaction. Ideally, if the reaction system reaches a stable state, the content ratio of each component can approximately reflect its activity ratio. This is because components with high content tend to have higher concentrations and are therefore more likely to participate in chemical reactions.

[0057] Furthermore, in order to improve the reference value of hydrogen fugacity, the present invention limits the mass percentage of encapsulated hydrocarbons in the encapsulated matrix to no less than 0.002%.

[0058] In a specific embodiment, the separation process of the package matrix includes:

[0059] Step 1, fully dissolving the encapsulation matrix in an organic solvent to obtain a dilute solution of the encapsulation matrix;

[0060] Step 2, uniformly dispersing the activated silica gel particles in an organic solvent to obtain a silica gel suspension; wherein the organic solvent in step 2 is the same as the organic solvent in step 1; the organic solvent is at least one of dichloromethane, chloroform, benzene, toluene, tetrahydrofuran, ethyl acetate, carbon disulfide, and nitrogen methyl pyrrolidone;

[0061] Step 3, under stirring conditions, dropwise add the encapsulation matrix dilute solution into the silica gel suspension, until all the encapsulation matrix dilute solution is added into the silica gel suspension, continue stirring and then stand until the silica gel particles are completely precipitated;

[0062] Step 4: filtering the system obtained in step 3 to separate the liquid and the solid silica gel particles; rotary evaporating the liquid, and separating the concentrated liquid obtained by rotary evaporation by column chromatography to obtain encapsulated hydrocarbons.

[0063] The effective separation of the encapsulated hydrocarbons in the encapsulated matrix is ​​the key to obtaining the olefin activity ratio. According to the inventor's previous research, the dispersed solid phase extraction method has a good non-destructive separation effect on the encapsulated hydrocarbons in the encapsulated matrix. The method uses a polar solvent to fully dilute the encapsulated matrix to disperse the encapsulated matrix aggregates and achieve the effect of releasing the encapsulated components. Then, with the help of solid phase materials such as silica gel particles, the polar macromolecules in the adsorption system are adsorbed, and finally the solid and liquid phases are separated by filtration to obtain the encapsulated components released in the liquid phase, and saturated hydrocarbons, aromatic hydrocarbons and non-hydrocarbon components are separated by column chromatography, wherein the saturated hydrocarbon components are the encapsulated hydrocarbons.

[0064] In a specific embodiment, the encapsulated hydrocarbon is detected by gas chromatography-mass spectrometry, wherein the detection conditions of the gas chromatography include a helium flow rate of 1 mL / min and a column box temperature program; the detection conditions of the mass spectrometry include a scanning range of m / z 50-450;

[0065] The column oven temperature program included holding at 50°C for 1 minute, then heating to 100°C at a rate of 20°C / min and holding for 1 minute, and finally heating to 310°C at a rate of 3°C / min and holding for 20 minutes.

[0066] Under the above conditions, gas chromatography-mass spectrometry detection can better identify and quantify the target hydrocarbons in the encapsulated hydrocarbons, which helps to further obtain reasonable and scientific results.

[0067] In the solution of the present invention, the target hydrocarbons are normal hydrocarbons.

[0068] Normal hydrocarbons are a series of substances in hydrocarbon compounds that are widely distributed, have obvious characteristics, are simple to identify, and are easy to quantify. Isohydrocarbons are relatively complex, difficult to identify, and have low content, making them unsuitable as target hydrocarbons.

[0069] Furthermore, the olefin conversion energy barrier of the target hydrocarbon is no higher than 481160 J / mol, i.e., 115 kcal / mol.

[0070] In a chemical reaction, during the process of reactants being converted into products, a transition state, i.e., a temporary state between reactants and products, is experienced. The transition state is the state with the highest energy during the reaction and is also the apex of the energy barrier. The energy barrier can be described by the energy of the transition state, i.e., the energy difference that needs to be overcome when the reactants are converted into the transition state. The height of the energy barrier determines the rate of the reaction, and the higher the energy, the slower the reaction rate. Therefore, the target hydrocarbon in the present invention has an alkene conversion energy barrier of no more than 481160 J / mol, i.e., 115 kcal / mol, which makes it easier to reach a balance in the reaction.

[0071] Furthermore, the target hydrocarbon is C 16 Hydrocarbon or C 18 Hydrocarbons. A series of even-carbon-number normal 1-olefins and normal alkanes with corresponding carbon numbers are widely present in the encapsulated hydrocarbons in the encapsulated matrix. Among them, hydrocarbons with carbon numbers greater than 19 are prone to cracking; hydrocarbons with carbon numbers less than 16 have a low content and are easy to volatilize during separation and treatment, resulting in significant changes in their composition; C 16 or C 18 Compounds are ubiquitous and account for a large proportion, and C 16 or C 18 The olefin conversion energy barrier of the compound is small, and it is easier to reach reaction equilibrium, so C 16 or C 18 The olefin equilibrium is an advantageous combination for calculating the hydrogen fugacity of a system.

[0072] In the scheme of the present invention, the package matrix includes at least one of asphaltene, kerogen, and solid asphalt.

[0073] The present invention utilizes the protective effect of typical organic geological macromolecules on the chemical balance of active organic small molecules. Therefore, asphaltene, kerogen, and solid asphalt, as typical organic geological macromolecules, can better deduce the hydrogen fugacity of the system by detecting and analyzing the chemical balance of the hydrocarbons they encapsulate.

[0074] In the solution of the present invention, the sedimentary organic matter includes at least one of organic matter in natural geological samples, artificially matured samples, and solid residues after chemical refining.

[0075] Organic matter in natural geological samples refers to the source material produced from specific sedimentary formations, for example, shale, coal and other organic-rich samples in oil and gas basins;

[0076] Artificially matured samples refer to products obtained by simulating the evolution of natural geological samples at a certain temperature, pressure and duration using thermal simulation experimental equipment, for example, products obtained by conducting a gold tube high temperature and high pressure closed system simulation experiment on source rocks;

[0077] Solid residues after chemical refining refer to the residual solid phase obtained after refining crude oil with lower oil quality, such as coke obtained after refining heavy oil.

[0078] The analysis of natural geological samples can characterize the hydrogen fugacity of sedimentary organic matter matrix in the actual formation environment, and then study the process and effect of hydrocarbon generation from sedimentary organic matter. The analysis of artificially matured or chemical refining samples can quantitatively study the distribution law of hydrogen fugacity under different conditions and help to build corresponding theoretical models.

[0079] The technical solution of the present application will be further explained below in conjunction with specific embodiments.

[0080] The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or conditions recommended by the manufacturers. The reagents used are commercially available or publicly available unless otherwise specified.

[0081] Embodiment 1:

[0082] This embodiment provides a method for obtaining the hydrogen fugacity of a system in sedimentary organic matter, which specifically includes the following steps:

[0083] (1) Based on the standard that the mass percentage of asphaltene in the rock sample is not less than 0.005%, source rock cores located in the western basin of China and with a depth not exceeding 8000m were selected.

[0084] (2) According to the Chinese petroleum and natural gas industry standards: SY / T 5118-2021 Determination of extract content in rocks and SY / T 5119-2016 Analysis of soluble organic matter in rocks and crude oil group components, the soluble organic matter in the sedimentary organic matter sample was extracted and the asphaltene therein was separated.

[0085] (3) Fully dissolve the asphaltene in dichloromethane to obtain a dilute asphaltene solution. Then evenly disperse the activated silica gel particles in dichloromethane to obtain a silica gel suspension. Under stirring conditions, drop the dilute asphaltene solution into the silica gel suspension drop by drop. After the dilute asphaltene solution is completely added to the silica gel suspension, continue stirring for 30 minutes, and then let the resulting mixed solution stand until the silica gel particles are completely precipitated. The resulting system is filtered to separate the upper liquid and solid silica gel particles. The solid silica gel particles are washed with dichloromethane three times, filtered again after washing, and the upper liquid and all the filtrate are rotary evaporated together. Finally, the concentrated solution obtained by rotary evaporation is separated by column chromatography to obtain saturated hydrocarbons, aromatic hydrocarbons and non-hydrocarbon components, among which the saturated hydrocarbon components are called encapsulated hydrocarbons.

[0086] (4) The encapsulated hydrocarbons were detected by gas chromatography-mass spectrometry detector, wherein the chromatographic detection conditions were as follows: the instrument was equipped with HP-5MS (5% phenylmethylpolysiloxane) fused silica capillary column (inner diameter 60m×0.25mm, film thickness 0.25μm), the carrier gas was helium, the flow rate was 1mL / min, the injection port temperature was 300°C, and non-split injection was performed. The initial temperature was 50°C and maintained for 1 minute, then increased to 120°C at 20°C / min and maintained for 1 minute, and then increased to 310°C at 3°C / min and maintained for 20 minutes. The mass spectrometry detection conditions were as follows: the mass spectrometry ion source used an EI source, the ionization energy was 70eV, and the scanning range was m / z 50-450. Based on the gas chromatography-mass spectrometry detection results, the C 16 Normal olefins and C 16 The composition of normal alkanes, and the corresponding olefin activity ratio was calculated to be 0.59.

[0087] (5) Obtain hydrogen fugacity through formula 1:

[0088]

[0089] Since the formation temperature of the source rock core is about 200°C, according to the formation temperature and Table 1, it can be known that the Gibbs free energy of olefin conversion becomes -17.50 kcal / mol, that is, -73220 J / mol.

[0090] Therefore, the hydrogen fugacity of the system containing the sedimentary organic matter is:

[0091]

[0092] That is, f H2 For 10 -7.85 bar.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for obtaining hydrogen fugacity in sedimentary organic matter, characterized in that: The steps include: Obtain the olefin-alkane activity ratio of target hydrocarbons in sedimentary organic matter; The hydrogen fugacity is obtained according to the olefin activity ratio, the Gibbs free energy change of olefin conversion and the system temperature of the deposited organic matter.

2. The method according to claim 1, characterized in that According to the olefin activity ratio, the Gibbs free energy change of olefin conversion and the system temperature of the deposited organic matter, the hydrogen fugacity is obtained, including: calculating the hydrogen fugacity according to Formula 1: Among them, f H2 is hydrogen fugacity, bar; ΔrGm is Gibbs free energy change for olefin conversion, J / mol; R is gas constant, 8.314 J / (mol·K); T is absolute temperature of the system where organic matter is deposited, K; α 烯烃 / α 烷烃 is the olefin activity ratio.

3. The method according to claim 1 or 2, characterized in that: The method of obtaining the olefin activity ratio of the target hydrocarbon in the sedimentary organic matter comprises the following steps: Obtaining the inclusion matrix in the sedimentary organic matter; Separating the encapsulated matrix to obtain encapsulated hydrocarbons; Performing gas chromatography-mass spectrometry detection on the encapsulated hydrocarbon to obtain the olefin-alkane activity ratio of the target hydrocarbon; Wherein, the mass percentage of the encapsulated hydrocarbon in the encapsulated matrix is ​​not less than 0.002%.

4. The method according to claim 3, characterized in that The separation process comprises: Step 1, fully dissolving the encapsulation matrix in an organic solvent to obtain a dilute solution of the encapsulation matrix; Step 2, uniformly dispersing the activated silica gel particles in an organic solvent to obtain a silica gel suspension; wherein the organic solvent in step 2 is the same as the organic solvent in step 1; the organic solvent is at least one of dichloromethane, chloroform, benzene, toluene, tetrahydrofuran, ethyl acetate, carbon disulfide, and nitrogen methyl pyrrolidone; Step 3, under stirring conditions, dripping the encapsulation matrix dilute solution into the silica gel suspension drop by drop, until the encapsulation matrix dilute solution is completely added to the silica gel suspension, continuing to stir and then standing until the silica gel particles are completely precipitated; Step 4: filtering the system obtained in step 3 to separate the liquid and the solid silica gel particles; rotary evaporating the liquid, and separating the concentrated liquid obtained by rotary evaporation by column chromatography to obtain encapsulated hydrocarbons.

5. The method according to claim 3, characterized in that: In the gas chromatography-mass spectrometry detection, the detection conditions of the gas chromatography include a helium flow rate of 1 mL / min and a column box temperature program; the detection conditions of the mass spectrometry include a scanning range of m / z50-450; The column box temperature program includes maintaining at 50°C for 1 minute, then heating to 100°C at a rate of 20°C / min and maintaining for 1 minute, and finally heating to 310°C at a rate of 3°C / min and maintaining for 20 minutes.

6. The method according to any one of claims 1 to 5, characterized in that: The target hydrocarbons are normal hydrocarbons.

7. The method according to claim 6, characterized in that The olefin conversion energy barrier of the target hydrocarbon is no higher than 481160 J / mol.

8. The method according to claim 6 or 7, characterized in that: The target hydrocarbon is C 16 Hydrocarbon or C 18 hydrocarbon.

9. The method according to any one of claims 3 to 5, characterized in that: The package matrix includes at least one of asphaltene, kerogen, and solid asphalt.

10. The method according to claim 1, characterized in that The sedimentary organic matter includes at least one of organic matter in natural geological samples, artificially matured samples, and solid residues after chemical refining.

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