Method for evaluating oil and gas generation process based on rock pyrolysis analysis spectrogram

Abstract

The invention provides a method for evaluating an oil and gas generation process based on a rock pyrolysis analysis spectrogram, and the method comprises the following steps: analyzing the bonding structure characteristics of organic matters of a characteristic rock sample, and determining the distribution interval of organic matter compounds in the pyrolysis spectrogram and the change rule of the thermal evolution degree; carrying out organic solvent extraction on the hydrocarbon source rock sample, carrying out pyrolytic analysis on the soluble organic matter compound obtained by extraction, and determining the distribution interval of the soluble organic matter compound in a pyrolytic spectrogram; the method comprises the following steps: performing pyrolysis analysis on a hydrocarbon source rock sample, performing peak separation treatment on a pyrolysis spectrogram, comparing with distribution intervals of organic matter compounds with different structures in the pyrolysis spectrogram, distribution intervals of soluble organic matter compounds in the pyrolysis spectrogram and change rules of thermal evolution degrees of the organic matter compounds, and judging an oil and gas generation stage. According to the method, the main parent material source, the phase state of the generated oil gas and the main chemical structure characteristics of oil gas components can be determined, and the quantity of the generated oil gas and the residual resource quantity are preliminarily judged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of organic geochemical analysis and oil-gas generation stage division in oil-gas exploration, and relates to a method for evaluating oil-gas generation process based on rock pyrolysis analysis spectrum. BACKGROUND

[0002] Oil-gas generation is an important content of oil-gas geology research, and the division of oil-gas generation stage helps oil workers to understand the maturity stage of source rock, make preliminary evaluation on the generated oil-gas resource quantity and remaining hydrocarbon generation potential, and make basic judgment on the geochemical properties of the generated oil-gas. The rock pyrolysis analysis spectrum separation research is also helpful to analyze the chemical bonding structure of organic matter and judge the type of organic matter and the properties of generated oil-gas. Therefore, the method for quickly dividing the oil-gas generation stage based on rock pyrolysis analysis spectrum resolution has important significance for serving oil-gas exploration.

[0003] The division of oil-gas generation stage is different in different periods. Tissot (1975) divided it into diagenesis, hypozonal metamorphism and epizonal metamorphism. Fu Jiamoto (1977) divided it into initial oil generation stage, low maturity stage, high maturity stage and final maturity stage. Huang Difan (1981, 1995) divided it into immature stage, mature stage and overmature stage. Yang Wanli (1981) divided it into immature stage, low maturity stage, high maturity stage and metamorphic stage. Cheng Keming (1996) divided it into immature stage, mature stage, high maturity stage and overmature stage. At present, the four-stage division method of Cheng Keming in 1996 is more commonly used. The advantage of this method is that it well describes the phase state of organic matter, such as the immature stage (Ro<0.5%), in which the organic matter is mainly solid kerogen; the mature stage (Ro=0.5%~1.3%), which is the main oil generation period, and the liquid oil is mainly accompanied by a small amount of natural gas. The crude oil in this stage is generally heavy oil, medium oil and light oil (the physical properties of crude oil generated by different types of source rocks are different), and the dry coefficient of hydrocarbon gas is small; the high maturity stage (Ro=1.3%~2.0%) is the condensate oil wet gas stage, in which the crude oil is condensate oil, the oil quality is significantly lighter than that in the mature stage, the gas content increases significantly, and the dry coefficient of hydrocarbon gas is obviously larger than that in the mature stage; the overmature stage (Ro>2.0%) is mainly the gas storage stage, in which the hydrocarbon gas is mainly dry gas (dry coefficient C1 / C 1-5 >0.95), and the oil content is very low. There are many indexes for evaluating the oil-gas generation stage, including optical, chemical and spectral indexes. The optical indexes include vitrinite reflectance (Ro), bitumen reflectance (Rb), marine vitrinite reflectance (R o M), graptolite reflectance (GRo), conodont alteration index (CAI), spore color and thermal alteration index (TAI), fluorescence color alteration (conodont CAIF, spore SCI), chemical class including maximum pyrolysis peak temperature (T max ), methylphenanthrene index (MPI), H / C atomic ratio, carbon isotope index, biomarker compounds, and spectral class indicators including cheese radical concentration N and paramagnetic susceptibility Xp, cheese ring average structure Xb, laser Raman spectrum parameters of organic carbonaceous matter, infrared spectrum, laser fluorescence probe, etc. Among the total indicators, Ro is the most effective indicator, and other indicators for dividing oil and gas generation stages need to use Ro as a scale, but the disadvantage of Ro is that it needs to be prepared into cheese (except coal), and it cannot detect old hydrocarbon source rocks with old age, high maturity and lack of vitrinite components, and the experience requirement for the tester is relatively high. Rock pyrolysis T max has the advantages of simple test method and low cost, and in the immature-mature stage, cheese T max has good correlation with Ro, but in the high evolution stage, T max is not accurate due to the low S2 peak of rock pyrolysis. The S2 peak of rock pyrolysis is called cheese cleavable hydrocarbon, and is generally studied as a peak, but previous studies have found that S2 should actually contain multiple peaks representing different organic matter. Peters (1986) found that there are two peaks, S2a and S2b, in rock pyrolysis. S2a is mainly some thermally unstable macromolecular organic matter, including humic acid and cheese precursor, etc. S2b may be mainly some high molecular weight cheese; Guo Fei (2017) found that S2a may be a better indicator of lake productivity by cracking sediments and algae; Utridge, et al (2007), Sanei, et al (2005) and others believe that S1 in rock pyrolysis is mainly some small molecular weight amorphous organic carbon, including free light, volatile plant oil and a part of light from humic acid sources; Carrie, et al (2009), Outridge, et al (2007) and others believe that RC, residual hydrocarbon or old carbon, includes the most difficult part of algae to pyrolyze, and some difficult-to-pyrolyze organic matter such as carbon black, etc., contains rich condensed aromatic structures. SUMMARY

[0004] To solve the technical problems existing in the prior art, the present application provides a method for evaluating the oil and gas generation process based on rock pyrolysis analysis spectrum, which uses the rock pyrolysis analysis spectrum to divide the oil and gas generation stage method, enriches the method system of oil and gas generation stage division, and through the oil and gas generation stage division, the main parent material source, the phase state of generated oil and gas, the main chemical structure characteristics of oil and gas composition, and the preliminary judgment of the amount of generated oil and gas and the remaining resource amount are given.

[0005] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for evaluating the oil and gas generation process based on rock pyrolysis analysis spectra, the method comprising:

[0007] Analyze the bonding structure characteristics of organic matter in characteristic rock samples to determine the distribution range of organic compounds with different structures in the pyrolysis spectrum and the changing pattern of the thermal evolution degree of organic compounds;

[0008] Extracting the source rock sample with an organic solvent, performing pyrolysis analysis on the soluble organic compounds obtained by the extraction, and determining the distribution range of the soluble organic compounds in the pyrolysis spectrum;

[0009] The source rock sample is subjected to pyrolysis analysis to obtain a pyrolysis spectrum, the pyrolysis spectrum of the source rock sample is subjected to peak separation, and is compared with the distribution range of the organic matter compounds with different structures in the pyrolysis spectrum, the distribution range of the soluble organic matter compounds in the pyrolysis spectrum, and the change pattern of the thermal evolution degree of the organic matter compounds to determine the oil and gas generation stage.

[0010] In the present invention, because different bonded organic matter structures have different activation energies, organic matter with different activation energies appears at different positions on the pyrolysis spectrum during pyrolysis, with organic matter with low activation energies appearing closer to the front and organic matter with high activation energies appearing closer to the back. The properties and scale of oil and gas generated by organic matter with different bonded structures vary, and based on this, the oil and gas generation stages can be divided according to the cracking stage of the pyrolysis of organic matter with different bonded structures.

[0011] As a preferred technical solution of the present invention, the characteristic rock sample has an organic matter type similar to that of the source rock sample and includes all thermal evolution stages.

[0012] As a preferred technical solution of the present invention, the thermal evolution stages include an immature stage, a mature stage, a highly mature stage and an over-mature stage.

[0013] As a preferred technical solution of the present invention, analysis of the bonding structure characteristics of organic matter in characteristic rock samples includes nuclear magnetic resonance analysis and pyrolysis analysis.

[0014] In the present invention, nuclear magnetic resonance analysis mainly refers to preparing kerogen by crushing the sample and measuring the carbon skeleton structure of the sample by a solid-state carbon nuclear magnetic resonance instrument.

[0015] In the present invention, pyrolysis analysis mainly refers to crushing the sample and analyzing it with a rock pyrolysis instrument.

[0016] As a preferred technical solution of the present invention, the characteristic rock samples are subjected to pyrolysis analysis to obtain the S2 peak and T max parameter.

[0017] The distribution interval of different structure organic matter compounds in the pyrolysis spectrum is mainly S2 peak.

[0018] In the application, the distribution interval of different structure organic matter compounds in the pyrolysis spectrum is mainly the distribution interval of aliphatic and aromatic compounds in the pyrolysis spectrum.

[0019] As a preferred technical solution of the application, the organic solvent comprises dichloromethane.

[0020] In the application, dichloromethane is only an example, and other organic solvents that can be used to extract soluble organic matter compounds in the source rock sample are also suitable for the application, and are not limited herein.

[0021] As a preferred technical solution of the application, the soluble organic matter compounds obtained by organic solvent extraction of the source rock sample include saturated hydrocarbons, aromatic hydrocarbons, non-hydrocarbons and asphaltene.

[0022] As a preferred technical solution of the application, pyrolysis analysis is performed on the extracted soluble organic matter compounds to obtain S1 peak parameters.

[0023] The distribution interval of the soluble organic matter compounds in the pyrolysis spectrum is mainly S1 peak, and part is S2 peak.

[0024] In the application, organic solvent extraction mainly refers to obtaining soluble organic matter by crushing the sample and extracting with dichloromethane, and obtaining saturated hydrocarbons, aromatic hydrocarbons, non-hydrocarbons and asphaltene components through a chromatographic column.

[0025] As a preferred technical solution of the application, the compound type of the residual organic matter of the source rock sample is determined according to the interval and relative abundance of S1 and S2 peaks, and the oil and gas generation stage is determined.

[0026] As a preferred technical solution of the application, the method for evaluating the oil and gas generation process based on rock pyrolysis analysis spectrum comprises:

[0027] The bonding structure characteristics of the organic matter of the characteristic rock sample are analyzed by nuclear magnetic resonance and pyrolysis analysis to obtain S2 peak and T max parameters, determine the distribution interval of different structure organic matter compounds in the pyrolysis spectrum and the change rule of the thermal evolution degree of the organic matter compounds;

[0028] The organic matter type of the characteristic rock sample is similar to that of the source rock sample, and the thermal evolution stage of the characteristic rock sample comprises an immature stage, a mature stage, a high-mature stage and an over-mature stage.

[0029] The hydrocarbon source rock sample is subjected to organic solvent extraction to obtain saturated hydrocarbon, aromatic hydrocarbon, non-hydrocarbon and asphaltene, pyrolysis analysis is carried out on the soluble organic matter compounds obtained by the extraction to obtain S1 peak parameters, and the distribution interval of the soluble organic matter compounds in the pyrolysis spectrum is determined;

[0030] The pyrolysis spectrum of the hydrocarbon source rock sample is obtained by pyrolysis analysis, the peak processing of the pyrolysis spectrum of the hydrocarbon source rock sample is carried out, and the distribution interval of the different structure organic matter compounds in the pyrolysis spectrum, the distribution interval of the soluble organic matter compounds in the pyrolysis spectrum and the change rule of the thermal evolution degree of the organic matter compounds are compared, the compound type of the residual organic matter of the hydrocarbon source rock sample is determined according to the interval and relative abundance of S1 and S2 peaks, and the oil and gas generation stage is judged.

[0031] Compared with the prior art, the present application has at least the following beneficial effects:

[0032] The present application provides a method for evaluating the oil and gas generation process based on rock pyrolysis analysis spectrum, which utilizes the rock pyrolysis analysis spectrum to divide the oil and gas generation stage, enriches the method system of dividing the oil and gas generation stage, and clearly determines the main parent material source, the phase state of the generated oil and gas, the main chemical structure characteristics of the oil and gas composition, and gives a preliminary judgment on the amount of the generated oil and gas and the remaining resource amount. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a flowchart of the method for evaluating the oil and gas generation process based on rock pyrolysis analysis spectrum provided by the present application embodiment;

[0034] Figure 2 is the solid-state nuclear magnetic resonance spectrum of organic matter in different thermal evolution stages in the present application embodiment

[0035] Figure 3 is the rock pyrolysis spectrum of soluble organic matter of different groups in the present application embodiment

[0036] Figure 4 is the rock pyrolysis spectrum of different thermal evolution stages in the present application embodiment;

[0037] Figure 5 is the hydrocarbon generation stage spectrum of the organic matter with aliphatic structure in the present application embodiment;

[0038] Figure 6 is the hydrocarbon generation stage spectrum of the organic matter with aromatic structure in the present application embodiment;

[0039] Figure 7 is the cracking stage spectrum of the residual soluble organic matter of the hydrocarbon source rock in the present application embodiment;

[0040] Figure 8 is the rock pyrolysis S2 peak T maxDivide oil and gas generation stage identification template map.

[0041] The application is further described in detail below. However, the examples described below are only simple examples of the application and do not represent or limit the protection scope of the application, and the protection scope of the application is subject to the claims. DETAILED DESCRIPTION

[0042] In order to better illustrate the application and facilitate the understanding of the technical solutions of the application, the typical but non-limiting embodiments of the application are as follows:

[0043] EMBODIMENT

[0044] The embodiment provides a method for evaluating an oil and gas generation process based on a rock pyrolysis analysis spectrum, a flowchart of the method is as shown in Figure 1 The method comprises the following steps.

[0045] Determine the types of organic matters represented by different intervals of the rock pyrolysis spectrum:

[0046] Collect rock samples of similar types of organic matters and covering each stage of immature, mature, high-mature and over-mature thermal evolution degrees or obtain rock samples of different thermal evolution stages by carrying out thermal pressure simulation experiments, carry out nuclear magnetic resonance analysis and pyrolysis analysis (results are as shown in Figure 2 and Figure 4 According to the results of the nuclear magnetic resonance analysis, delimit the distribution intervals of the aliphatic organic compounds and the aromatic organic compounds in the pyrolysis spectrum, S2 2 peak represents the aliphatic organic compounds in the kerogen, S2 3 peak represents the aromatic organic compounds in the kerogen.

[0047] Collect the source rock samples, crush them to more than 80 meshes, extract them by using dichloromethane, separate the extracted soluble organic matters by using a chromatographic column to obtain four group components of saturated hydrocarbons, aromatic hydrocarbons, non-hydrocarbons and asphaltene, and analyze the four components by using a rock pyrolysis instrument to determine the distribution intervals of different types of soluble organic matters in the pyrolysis spectrum (as shown in Figure 3 S1 mainly represents the saturated hydrocarbons and the aromatic hydrocarbons in the soluble organic matters, S2 1 mainly represents the saturated hydrocarbons and the aromatic hydrocarbons in the soluble organic matters, and a small part of small-molecule heteroatomic non-hydrocarbons and asphaltene, and the non-hydrocarbons and the asphaltene are mainly distributed in the S2 2 peak interval, and it can be seen that the S2 2 peak interval is not all kerogen, but also a certain amount of soluble organic matter.

[0048] Determine the rock pyrolysis spectrum and Tmax characteristics of different evolution stages:

[0049] According to the results of nuclear magnetic resonance analysis and pyrolysis analysis of source rocks at different thermal evolution stages, it can be divided into three stages: Stage 1, Ro < 1.30% (experimental temperature 365 ° C), S2 2 The peak decreases and S1 increases ( Figure 5 ), represents the hydrocarbon generation stage of aliphatic kerogen cracking, the products are mainly oil and supplemented by natural gas, T max There is a good correlation with Ro%, T max Generally <500℃( Figure 8 ); Stage 2, Ro = 1.30% ~ 2.5% (experimental temperature 385 ℃ ~ 475 ℃), with S2 3 The peak decreases and S1 decreases as the characteristics ( Figure 6 ), representing the aromatic kerogen cracking hydrocarbon generation stage, the product is mainly gas, T max No correlation with Ro%, T max Distributed in 520℃~540℃( Figure 8 ); Stage 3, Ro>2.5% (experimental temperature 500℃~550℃), characterized by extremely low peak and S1 as the main peak ( Figure 7 ), represents the hydrocarbon generation stage of residual soluble organic matter, the product is mainly gas, T max No correlation with Ro%, T max It is significantly lower than the first two stages, characterized by temperatures below 400°C ( Figure 8 ).

[0050] Steps for dividing oil and gas generation stages:

[0051] The samples were subjected to rock pyrolysis analysis according to S1 and S2. 1 、S2 2 、S2 3 The distribution interval is processed by peak separation.

[0052] The oil and gas generation stages are divided according to the relative abundance of the four peaks and combined with Tmax. 2 Main, T max <500℃ is the hydrocarbon generation stage of aliphatic kerogen cracking, which basically corresponds to the mature stage; 3 Main, T max >500℃ is the aromatic kerogen cracking hydrocarbon generation stage, which basically corresponds to the high maturity stage; mainly S1, T max <400℃ is the gas generation stage of residual hydrocarbon cracking, which basically corresponds to the over-mature stage.

[0053] The applicant declares that the detailed structural features of the present application are illustrated by the above-mentioned embodiments, but the present application is not limited to the above-mentioned detailed structural features, i.e. it does not mean that the present application must rely on the above-mentioned detailed structural features to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the components selected by the present application, addition of auxiliary components, selection of specific modes, etc. all fall within the protection scope and disclosure scope of the present application.

[0054] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the specific details in the above-mentioned embodiments, and within the technical concept scope of the present application, various simple modifications can be made to the technical solutions of the present application, and these simple modifications all belong to the protection scope of the present application.

[0055] In addition, it should be noted that each specific technical feature described in the above-mentioned specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combination manners.

[0056] In addition, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the idea of the present application, and it should be considered as the disclosed content of the present application.

Claims

1. A method for evaluating a hydrocarbon generation process based on a rock pyrolysis analysis spectrum, characterized by, The method comprises: analyzing the bonding structure characteristics of the organic matter of the characteristic rock sample, determining the distribution range of different structural organic matter compounds in the pyrolysis spectrum and the variation law of the thermal evolution degree of the organic matter compounds; performing organic solvent extraction on the source rock sample, performing pyrolysis analysis on the soluble organic matter compounds obtained by the extraction, and determining the distribution range of the soluble organic matter compounds in the pyrolysis spectrum; performing pyrolysis analysis on the source rock sample to obtain a pyrolysis spectrum, performing peak separation processing on the pyrolysis spectrum of the source rock sample, and comparing the distribution range of the different structural organic matter compounds in the pyrolysis spectrum, the distribution range of the soluble organic matter compounds in the pyrolysis spectrum and the variation law of the thermal evolution degree of the organic matter compounds, to determine the oil and gas generation stage.

2. The method of claim 1, wherein, The organic matter types of the characteristic rock sample and the source rock sample are similar, and all thermal evolution stages are included.

3. The method of claim 2, wherein, The thermal evolution stages include the immature stage, the mature stage, the high-mature stage and the over-mature stage.

4. The method of claim 1, wherein, The analysis of the bonding structure characteristics of the organic matter of the characteristic rock sample includes nuclear magnetic resonance analysis and pyrolysis analysis.

5. The method of claim 4, wherein, Thermal analysis of characteristic rock samples to obtain S2 peak and T max parameters.

6. The method of claim 1, wherein, The organic solvent includes dichloromethane.

7. The method of claim 1, wherein, The soluble organic matter compounds obtained by the organic solvent extraction on the source rock sample include saturated hydrocarbons, aromatic hydrocarbons, non-hydrocarbons and asphaltene.

8. The method of claim 1, wherein, The pyrolysis analysis on the soluble organic matter compounds obtained by the extraction obtains S1 peak parameters.

9. The method according to claims 4 and 8, characterized in that, According to the range and relative abundance of S1 peak and S2 peak, the compound type of the residual organic matter of the source rock sample is determined, and the oil and gas generation stage is determined.

10. The method according to claims 1-9, characterized in that, The method comprises: The bonding structure characteristics of the organic matter of the characteristic rock sample are analyzed by nuclear magnetic resonance and pyrolysis analysis, to obtain S2 peaks and T max Parameters, determine the distribution interval of different structural organic matter compounds in the pyrolysis spectrum and the change rule of the thermal evolution degree of the organic matter compounds; The organic matter types of the characteristic rock sample and the source rock sample are similar, and the thermal evolution stages of the characteristic rock sample include the immature stage, the mature stage, the high-mature stage and the over-mature stage; performing organic solvent extraction on the source rock sample to obtain saturated hydrocarbons, aromatic hydrocarbons, non-hydrocarbons and asphaltene, performing pyrolysis analysis on the soluble organic matter compounds obtained by the extraction to obtain S1 peak parameters, and determining the distribution range of the soluble organic matter compounds in the pyrolysis spectrum; performing pyrolysis analysis on the source rock sample to obtain a pyrolysis spectrum, performing peak separation processing on the pyrolysis spectrum of the source rock sample, and comparing the distribution range of the different structural organic matter compounds in the pyrolysis spectrum, the distribution range of the soluble organic matter compounds in the pyrolysis spectrum and the variation law of the thermal evolution degree of the organic matter compounds, according to the range and relative abundance of S1 peak and S2 peak, to determine the compound type of the residual organic matter of the source rock sample, and to determine the oil and gas generation stage.

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