Oil source or oil-oil comparison method based on asphaltene wrapped hydrocarbon protogenicity information
By separating encapsulated hydrocarbons from asphaltenes and detecting components such as n-1-olefins using gas chromatography-mass spectrometry, the failure problem of traditional oil source correlation methods under strong post-modification effects has been solved, achieving high-precision oil source correlation.
Patent Information
- Application Number
- CN202511557735.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-29
- Publication Date
- 2026-02-06
AI Technical Summary
Traditional oil source correlation methods fail under strong post-modification effects, as free hydrocarbon information is destroyed, leading to ambiguity and unreliability.
Hydrocarbons encapsulated in asphalt are separated and analyzed using physical methods, and components such as n-1-olefins are detected using techniques such as gas chromatography-mass spectrometry to ensure the accuracy of the original information.
In complex altered reservoirs such as those undergoing biodegradation, it can accurately and reliably correlate oil sources, preserve original geochemical information, and avoid chemically destructive interference.
Smart Images
Figure CN121476447A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of petroleum geological exploration, and particularly relates to a method for oil source or oil-oil correlation based on asphaltene-encapsulated hydrocarbon primary information. BACKGROUND
[0002] Oil source correlation (oil-rock correlation) and oil-oil correlation are core links in petroleum geology and oil and gas geochemistry research, and play a crucial role in clarifying oil and gas accumulation process, tracing oil and gas sources and evaluating exploration potential. Traditional oil source correlation methods mainly rely on free-state biomarker compounds (such as steranes and hopanes) and stable carbon isotope compositions of component or series compounds in crude oil or source rock extracts. However, after the oil and gas reservoirs undergo strong post-reformation (such as biodegradation, thermal alteration, water washing, etc.), the molecular composition and isotope values of these free hydrocarbon components will change significantly, resulting in the original hydrocarbon generation information carried by them being masked or distorted, thus making the traditional correlation methods ineffective or multi-solution.
[0003] Asphaltene, as an important high molecular weight component in petroleum and sedimentary organic matter, encapsulates and protects a series of pre-existing small molecule hydrocarbons (n-alkanes, alkenes, cyclic hydrocarbons, etc.) in its complex three-dimensional network structure caused by self-aggregation. These encapsulated hydrocarbons are largely isolated from the external environment due to the effective physical shielding of the asphaltene macromolecular skeleton, thus avoiding the influence of the later secondary alteration process, and are considered to retain the original geochemical information of the oil and gas when it was first formed. Therefore, asphaltene-encapsulated hydrocarbons are regarded as an ideal research object for restoring the original reservoir information and conducting high-precision oil source correlation.
[0004] In the prior art, some studies have attempted to release the encapsulated hydrocarbons by destroying the asphaltene structure through chemical degradation (such as mild oxidative degradation) and then conduct geochemical analysis, but the inherent chemical damage introduces unavoidable systematic errors, which seriously limits the application reliability of the method in precise geochemical research. Another approach is to use pyrolysis (such as gold tube thermal simulation, catalytic hydrogenation pyrolysis) to crack the asphaltene, hoping to release the encapsulated hydrocarbons or weakly bonded hydrocarbons through thermal action, but the pyrolysis method has more complex interference factors, making it difficult to accurately obtain single encapsulated hydrocarbon information. SUMMARY
[0005] The first object of the present application is to provide a method for oil source or oil-oil correlation based on asphaltene-encapsulated hydrocarbon primary information, which can solve the long-standing technical problem that effective oil source correlation cannot be carried out in complex altered reservoirs such as strong biodegradation due to the destruction of free hydrocarbon information.
[0006] The method for oil source or oil-oil correlation based on asphaltene-encapsulated hydrocarbon primary information provided by the present application comprises the following steps: S1. Extracting and purifying asphaltene components from crude oil and / or potential hydrocarbon source rock samples to be compared; S2. Physically separating inclusion hydrocarbons from the purified asphaltene components to obtain saturated hydrocarbons, aromatic hydrocarbons and non-hydrocarbons; S3. Performing specific geochemical analysis on the inclusion saturated hydrocarbons separated in step S2, i.e. using gas chromatography-mass spectrometry to detect and analyze n-alkane series compounds in the inclusion saturated hydrocarbon components to identify the effectiveness of the inclusion hydrocarbon primary information; S4. Performing fine geochemical analysis on the inclusion hydrocarbon components with good primary information identified in step S3 to obtain geochemical parameters thereof; S5. Oil source or oil oil correlation and identification, comparing the geochemical parameters obtained in step S4 of different samples to be compared, and judging the genetic relationship between different samples to be compared according to the similarity degree of the primary information in the geochemical parameters, to complete the oil source or oil oil correlation.
[0007] Preferably, the step S1 of extracting asphaltene components specifically includes: Obtaining asphaltene components by group component separation from soluble organic matter extracted by organic reagents from crude oil and / or potential hydrocarbon source rock samples to be compared.
[0008] Preferably, the step S1 of purifying asphaltene components specifically includes: Firstly, the asphaltene components are extracted by low-polarity reagents, and then the asphaltene components are extracted again by polarity reagents and collected by reflux, the collected asphaltene is dissolved in polarity reagents to make it slightly dissolved into oil-like flowable state, then excessive low-polarity reagents are added and ultrasonic is performed, after ultrasonic, centrifugal elution is performed to the upper clear liquid without color, and the asphaltene solid, i.e. the purified asphaltene components, is collected.
[0009] Preferably, the low-polarity reagents in the first extraction include any one of n-pentane, n-hexane or petroleum ether; and the polarity reagents in the second extraction use dichloromethane.
[0010] Preferably, the centrifugal elution after ultrasonic specifically includes: after ultrasonic for 1-2 min, centrifugal elution is performed at a speed of 3000-4000 rad / min to make the asphaltene precipitate adhere to the bottom of the centrifugal tube, and the upper clear liquid of the centrifugal tube is removed, and the above-mentioned slightly dissolved-centrifugal elution process is repeated until the upper clear liquid is colorless.
[0011] Preferably, the step S2 of physically separating inclusion hydrocarbons from the purified asphaltene components specifically includes: The asphaltene component is fully dissolved in an organic solvent to obtain an asphaltene dilute solution, the asphaltene concentration in the asphaltene dilute solution being not more than 0.5 mg / mL; the activated silica gel particles are uniformly dispersed in the organic solvent to obtain a silica gel suspension; the asphaltene dilute solution is added dropwise into the silica gel suspension under stirring, the silica gel particles are completely precipitated after the asphaltene dilute solution is completely added into the silica gel suspension and stirring is continued for a period of time; the precipitated system is filtered to separate the liquid and the solid silica gel particles; then the liquid is rotary evaporated; and the concentrated liquid obtained by rotary evaporation is separated by column chromatography to obtain saturated hydrocarbons, aromatic hydrocarbons and non-hydrocarbons.
[0012] The key of this step is to require that the selected method must be non-chemical destructive, so as to ensure that the released inclusion hydrocarbons can maximize the preservation of their original molecular composition (especially active components such as n-alkene) and isotopic information, and provide reliable data basis for subsequent comparison.
[0013] Preferably, the step S3 of identifying the effectiveness of the inclusion hydrocarbon original information specifically includes: The effectiveness of the inclusion hydrocarbon original information is identified by identifying whether a series of n-alkene compounds exist in the inclusion saturated hydrocarbon component; if the series of n-alkenes are detected, it is determined that the inclusion hydrocarbon original information is good, and subsequent comprehensive comparison and analysis can be carried out; if not, the sample or separation process needs to be re-evaluated.
[0014] The n-alkene is a "original fingerprint" with high chemical activity and easy to be degraded and destroyed, and its existence is direct evidence that the inclusion hydrocarbon is not affected by secondary alteration and is good in originality. This step ensures the originality and reliability of the data for subsequent comparison and analysis.
[0015] Preferably, the step S4 of fine geochemical analysis specifically includes one or more of gas chromatography-mass spectrometry, element-isotope ratio mass spectrometry and gas chromatography-isotope ratio mass spectrometry.
[0016] Preferably, the geochemical parameters in the step S4 specifically include the complete biomarker distribution and related ratio parameters in the inclusion hydrocarbon component, and stable isotope composition of components or compounds.
[0017] Preferably, the biomarkers include steranes, terpanes, n-alkane / alkene series.
[0018] Beneficial effects: This invention provides a complete technical process for solving the problem of oil source or oil-oil correlation in highly biodegradable reservoirs. It eliminates the need for free hydrocarbons obtained by separating conventional group components that have been damaged, and directly and non-destructively (without chemical damage) obtains and utilizes the original information retained by the encapsulated hydrocarbons protected by asphaltenes. By identifying the original information of the encapsulated hydrocarbons, oil source-oil-oil correlation can be performed more accurately and reliably, which has important practical value for guiding oil and gas exploration.
[0019] The method provided by this invention is designed for oil reservoirs that have suffered severe secondary alteration such as biodegradation and where traditional correlation methods have failed. It enables more accurate and reliable oil-source-oil-oil correlation and ensures the fidelity and reliability of geochemical information throughout the entire process from sample preparation to final identification. Attached Figure Description
[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0021] Figure 1 This is an ion flow diagram of saturated hydrocarbons encapsulated in asphaltenes of oils A and B in a specific embodiment of the present invention (Pr, pterostilbene; Ph, phytane). Figure 2 This is the m / z 85 mass chromatogram of saturated hydrocarbons encapsulated in asphaltenes of oil A and oil B in specific embodiment 1 of the present invention; Figure 3 The m / z 191 and m / z 217 mass chromatograms of asphaltenes-encapsulated saturated hydrocarbons in two oil samples, A and B, in Specific Embodiment 1 of the present invention; Figure 4 The total ion chromatogram and m / z 85 mass chromatogram of free saturated hydrocarbons in oil A and oil B in Comparative Example 1 of this invention are shown. Figure 5 The images show the mass chromatograms of free saturated hydrocarbons in oil A and oil B in Comparative Example 1 of this invention, at m / z 191 and m / z 217. Detailed Implementation
[0022] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0023] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0025] Method Implementation Examples A method for comparing oil sources or oils based on the intrinsic hydrocarbon information encapsulated in asphaltenes includes the following steps: S1. Extract and purify asphaltenes from crude oil and / or potential source rock samples to be compared; The extraction of asphaltenes specifically includes: According to industry standard SY / T5119, asphaltene components are obtained from the soluble organic matter extracted from the target sample, i.e., the crude oil and / or potential source rock sample to be compared, by means of group component separation, generally not less than 10 mg; Purifying asphaltenes specifically includes: First, the asphaltenes are initially extracted using low-polarity reagents such as n-pentane, n-hexane, or petroleum ether (Soxhlet extraction for 48 hours) to remove residual free hydrocarbon components. Then, the asphaltenes are extracted again using a polar reagent, dichloromethane, and refluxed for collection. The collected asphaltenes are dissolved in a trace amount of a polar reagent such as dichloromethane (generally not exceeding 10 μL / mg asphaltenes) to achieve a slightly dissolved, oily, flowable state. Then, an excess of low-polarity reagents such as n-hexane or petroleum ether (generally not less than 1 mL / mg asphaltenes) is added, followed by sonication for 1-2 minutes. After sonication, the mixture is centrifuged at 3000-4000 rad / min for 5 minutes to allow the asphaltenes to precipitate and adhere to the bottom of the centrifuge tube. The supernatant is removed, and the above slightly dissolved-centrifuged elution process is repeated until the supernatant is colorless. The collected asphaltenes solid is the purified asphaltenes component. This purification step ensures that the subsequent analysis focuses on pure asphaltenes and their encapsulated hydrocarbons, minimizing interference from free and adsorbed hydrocarbons.
[0026] S2. Physically separate the encapsulated hydrocarbons from the purified asphaltenes to obtain saturated hydrocarbons, aromatic hydrocarbons, and non-hydrocarbons; The physical separation of encapsulated hydrocarbons from purified asphaltenes specifically includes: Asphaltene components were fully dissolved in an organic solvent to obtain a dilute asphaltene solution with a concentration not exceeding 0.5 mg / mL. Activated silica gel particles were uniformly dispersed in the organic solvent to obtain a silica gel suspension. Under stirring conditions, the dilute asphaltene solution was added dropwise to the silica gel suspension. After all the dilute asphaltene solution was added, stirring was continued for a period of time, followed by standing until the silica gel particles completely precipitated. The precipitated system was filtered to separate liquid and solid silica gel particles. The liquid was then subjected to rotary evaporation. The concentrated liquid obtained from the rotary evaporation was then separated by column chromatography to obtain saturated hydrocarbons, aromatics, and non-hydrocarbons. Specific experimental parameters are disclosed in patent CN111205882A.
[0027] The key to this step is that the method used must be non-chemically destructive to ensure that the released encapsulated hydrocarbons retain their original molecular composition (especially active components such as n-1-olefins) and isotopic information to the greatest extent possible, providing a reliable data basis for subsequent comparisons.
[0028] S3. Perform specific geochemical analysis on the encapsulated saturated hydrocarbons separated in step S2, that is, use gas chromatography-mass spectrometry to detect and analyze the n-chain hydrocarbon series compounds in the encapsulated saturated hydrocarbon components to determine the validity of the original information of the encapsulated hydrocarbons. The effectiveness of determining the original information of the encapsulated hydrocarbons specifically includes: The validity of the original information of the encapsulated hydrocarbon can be determined by identifying whether a series of n-1-olefin compounds are present in the encapsulated saturated hydrocarbon component. If the n-1-olefin series is detected, the original information of the encapsulated hydrocarbon is considered to be good, and subsequent comprehensive comparative analysis can be carried out. If it is not detected, the sample or separation process needs to be re-evaluated.
[0029] S4. For encapsulated hydrocarbon components with good original information, conduct detailed geochemical analysis to obtain their geochemical parameters; Refined geochemical analysis specifically includes one or more of the following: gas chromatography-mass spectrometry, element-isotope ratio mass spectrometry, and gas chromatography-isotope ratio mass spectrometry.
[0030] Geochemical parameters specifically include: the complete distribution of biomarkers and related ratio parameters within hydrocarbon components, and the stable isotopic composition of components or compounds (such as δ¹⁸O₂). 13 C); Biomarkers include steranes, terpenes, and n-alkanes / olefins.
[0031] S5. Oil source or oil-oil comparison and identification: The geochemical parameters obtained in step S4 of different samples to be compared are compared. Based on the degree of similarity of the primary information in the geochemical parameters, the kinship between different samples to be compared is determined. This can avoid the destructive impact of secondary alteration such as biodegradation on free hydrocarbon information and complete the oil source or oil-oil comparison.
[0032] The following examples use the method described in this invention to compare and analyze two known homologous heavy oil samples that have undergone severe biodegradation, aiming to illustrate the specific implementation methods and technical effects of this invention in solving the problem of oil source correlation in complex oil and gas reservoirs.
[0033] Specific Example 1: Oil-to-oil comparison of biodegradable heavy oil in a certain area of an oilfield in western China A method for comparing oil sources or oils based on the intrinsic hydrocarbon information encapsulated in asphaltenes includes the following steps: S1. Select extra-heavy oil sample A and ordinary heavy oil sample B from an oilfield in western China as the analysis objects. The geological background indicates that the two are of the same origin, but oil A has suffered from secondary alteration such as biodegradation to a greater extent than oil B, and the geochemical information of free hydrocarbons in both has been severely lost, making it difficult for traditional oil-oil correlation methods to work.
[0034] The crude oil sample was processed according to the extraction and purification methods in the method embodiment to obtain purified asphaltenes. S2. Physically separate the encapsulated hydrocarbons from the purified asphaltenes to obtain saturated hydrocarbons, aromatic hydrocarbons, and non-hydrocarbons; The specific experimental parameters for the physical separation of encapsulated hydrocarbons from purified asphaltenes have been disclosed in patent CN111205882A; S3. Perform specific geochemical analysis on the encapsulated saturated hydrocarbons separated in step S2, that is, use gas chromatography-mass spectrometry to detect and analyze the n-chain hydrocarbon series compounds in the encapsulated saturated hydrocarbon components to determine the validity of the original information of the encapsulated hydrocarbons. A series of characteristic n-alkanes and n-1-olefins were identified in the ion chromatograms of asphaltenes-encapsulated saturated hydrocarbons in oils A and B, such as... Figure 1 As shown, where C 16 C 18 C 20 The n-alkenes appear in series and paired with n-alkanes of the same carbon number. This indicates that the encapsulated hydrocarbons have good originality and are suitable for subsequent comprehensive comparative analysis. S4. For encapsulated hydrocarbon components with good original information, conduct detailed geochemical analysis to obtain their geochemical parameters; Distribution of measured biomarkers: The m / z 85 mass chromatograms of asphaltenes-encapsulated saturated hydrocarbons in oils A and B are shown below. Figure 2As shown in the figure, a series of characteristic n-alkanes were identified, and it can be seen that the distribution characteristics of n-alkanes are highly similar: the carbon number is mainly distributed in... n C 16 ~nC 28 The main peak carbon is n C 22 Furthermore, it does not possess an odd-even advantage.
[0035] The mass chromatograms of asphaltenes-encapsulated saturated hydrocarbons in oil samples A and B are shown below (m / z 191 and m / z 217). Figure 3 As shown in the figure, the steranes and terpenes are well-distributed and have similar characteristics. In particular, gammacerane was detected in both, and C... 27 The predominance of regular steranes suggests a similar origin and sedimentary environment (e.g., brackish water, stratified water). Furthermore, both oil samples exhibited intact C1 hydrocarbons within their inclusions. 31 ~C 35 The hopane series, all of which share a similar "slight tailing" distribution characteristic, further corroborates their homology in origin.
[0036] Biomarker parameters: Oil samples A and B contain saturated hydrocarbons C. 31 The 22S / (22S+22R) ratios of hopane were all 0.61, while the 20S / (20S+20R) ratios of ααα-C29 steranes were 0.60 and 0.59, respectively. 29 The ββ / (ββ+αα) ratios of steranes were 0.41 and 0.38, respectively. These parameters are often used to indicate the degree of thermal evolution of sedimentary organic matter. Although the thermal evolution of hydrocarbons encapsulated in asphaltenes is relatively independent and lagging, and may not reflect the true degree of thermal evolution of sedimentary organic matter, the high similarity of the above parameters indicates good comparability between the two oil samples.
[0037] S5. Oil source or oil-oil comparison and identification: The geochemical parameters obtained from the detection of oil A and oil B are compared. Based on the degree of similarity of the primary information in the geochemical parameters, the kinship between different samples to be compared is determined. This can avoid the destructive impact of secondary alteration such as biodegradation on free hydrocarbon information and complete the oil source or oil-oil comparison. Identification results: Although the physical properties (viscosity) and free hydrocarbon composition of oil A and oil B are very different, the combination and distribution characteristics of their hydrocarbon-encapsulated biomarkers show a high degree of consistency, supporting a good kinship between the two.
[0038] Specific Comparison Example 1 An oil-to-oil correlation method was proposed, using extra-heavy oil sample A and ordinary heavy oil sample B from an oilfield in western China as analytical objects. Geological backgrounds indicated that both samples originated from the same source. The traditional oil-to-oil correlation method was employed, including the following steps: Free hydrocarbons in two oil samples were analyzed. The results are as follows: Figure 4 and Figure 5 As shown, the total ion chromatograms (TIC) of free saturated hydrocarbons in oils A and B show complete loss of the n-alkanes, with obvious unresolved complex mixture (UCM) bulges, making it impossible to clearly identify characteristic compounds. The distribution characteristics of the n-alkanes differ significantly, with oil A exhibiting a bimodal pattern and oil B a unimodal pattern. Among the terpenoid compounds, the tricyclic terpenoids (C...) in both oils... 21 -C 22 -C 23 The relative distributions of tricyclic terpenes and pentacyclic terpenes are different, and the relative abundances of tricyclic terpenes and pentacyclic terpenes are different; rearranged steranes are the main components in the sterane series, indicating that they have suffered severe biodegradation and the effective information has been almost completely destroyed, so the two are not comparable.
[0039] Therefore, traditional comparison methods cannot effectively compare oils based on the distribution characteristics of compounds in free saturated hydrocarbons in oils A and B, and thus cannot determine the phylogenetic relationship between them.
[0040] The analysis results of Specific Example 1 and Specific Comparative Example 1 demonstrate that the method of utilizing the originality of asphaltenes-encapsulated hydrocarbons in this invention to solve the correlation problem in strongly biodegradable reservoirs is correct and effective. This invention successfully provides a reliable technical means to overcome biodegradation interference. Even when free hydrocarbon information has been severely damaged, the asphaltenes-encapsulated hydrocarbons obtained based on the method of this invention can still completely preserve key information such as the original source rock and sedimentary environment. The high similarity in the biomarker characteristics and related parameters of hydrocarbon encapsulated hydrocarbons in oil A and oil B strongly indicates that they originate from the same source rock and are related.
[0041] In summary, this invention successfully overcomes the interference of secondary alteration processes such as biodegradation on biomarker-based information comparison, providing a reliable technical solution for oil-source / oil-oil correlation in complex heavy oil reservoirs.
[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for comparing oil sources or oil-oil profiles based on the intrinsic hydrocarbon information encapsulated in asphaltenes, characterized in that, Includes the following steps: S1. Extract and purify asphaltenes from crude oil and / or potential source rock samples to be compared; S2. Physically separate the encapsulated hydrocarbons from the purified asphaltenes to obtain saturated hydrocarbons, aromatic hydrocarbons, and non-hydrocarbons; S3. Perform specific geochemical analysis on the encapsulated saturated hydrocarbons separated in step S2, that is, use gas chromatography-mass spectrometry to detect and analyze the n-chain hydrocarbon series compounds in the encapsulated saturated hydrocarbon components to determine the validity of the original information of the encapsulated hydrocarbons. S4. For encapsulated hydrocarbon components with good original information, conduct detailed geochemical analysis to obtain their geochemical parameters; S5. Oil source or oil-oil comparison and identification: The geochemical parameters obtained in step S4 of different samples to be compared are compared. Based on the degree of similarity of the primary information in the geochemical parameters, the kinship between different samples to be compared is determined, and the oil source or oil-oil comparison is completed.
2. The method according to claim 1, characterized in that, The extraction of asphaltenes in step S1 specifically includes: Asphaltenes were obtained from soluble organic matter extracted from crude oil and / or potential source rock samples by organic reagent extraction and group component separation.
3. The method according to claim 1, characterized in that, The purification of asphaltenes in step S1 specifically includes: First, a low-polarity reagent is used to perform an initial extraction of the asphaltene components. Then, a polar reagent is used to extract the asphaltene components again and reflux them for collection. The collected asphaltene is dissolved in a polar reagent until it is slightly dissolved into an oily, flowable state. Then, an excess of low-polarity reagent is added and the mixture is sonicated. After sonication, the mixture is centrifuged and eluted until the supernatant is colorless. The asphaltene solid is then collected, which is the purified asphaltene component.
4. The method according to claim 3, characterized in that, The low-polarity reagent used in the initial extraction includes any one of n-pentane, n-hexane, or petroleum ether; the polarity reagent used in the secondary extraction is dichloromethane.
5. The method according to claim 3, characterized in that, The ultrasonic centrifugation elution process specifically includes: after ultrasonication for 1-2 minutes, centrifugation is performed at a speed of 3000-4000 rad / min to allow the asphaltene precipitate to adhere to the bottom of the centrifuge tube, and the supernatant is removed. The above micro-dissolution-centrifugation elution process is repeated until the supernatant is colorless.
6. The method according to claim 1, characterized in that, The physical separation of encapsulated hydrocarbons from the purified asphaltenes in step S2 specifically includes: The asphaltene component was fully dissolved in an organic solvent to obtain a dilute asphaltene solution, wherein the asphaltene concentration in the dilute asphaltene solution did not exceed 0.5 mg / mL. Activated silica gel particles were uniformly dispersed in an organic solvent to obtain a silica gel suspension. Under stirring conditions, the dilute asphaltene solution was added dropwise to the silica gel suspension. After all the dilute asphaltene solution was added to the silica gel suspension, stirring was continued for a period of time, and then the mixture was allowed to stand until the silica gel particles completely precipitated. The precipitated system was filtered to separate liquid and solid silica gel particles. The liquid was then subjected to rotary evaporation. The concentrated liquid obtained from the rotary evaporation was then separated by column chromatography to obtain saturated hydrocarbons, aromatic hydrocarbons, and non-hydrocarbons.
7. The method according to claim 1, characterized in that, The specific steps in step S3 to determine the validity of the original information of the encapsulated hydrocarbon include: The validity of the original information of the encapsulated hydrocarbon can be determined by identifying whether a series of n-1-olefin compounds are present in the encapsulated saturated hydrocarbon component. If the n-1-olefin series is detected, the original information of the encapsulated hydrocarbon is considered to be good, and subsequent comprehensive comparative analysis can be carried out. If it is not detected, the sample or separation process needs to be re-evaluated.
8. The method according to claim 1, characterized in that, The detailed geochemical analysis in step S4 specifically includes one or more of the following: gas chromatography-mass spectrometry, element-isotope ratio mass spectrometry, and gas chromatography-isotope ratio mass spectrometry.
9. The method according to claim 1, characterized in that, The geochemical parameters in step S4 specifically include: the complete distribution of biomarkers and related ratio parameters in the encapsulated hydrocarbon components, and the stable isotopic composition of the components or compounds.
10. The method according to claim 9, characterized in that, The biomarkers include steranes, terpenes, and n-alkane / olefin series.