Method for comprehensively determining filling proportion of high-maturity crude oil in mixed-source crude oil

Abstract

The invention belongs to the technical field of oil and gas field exploration, and relates to a method for comprehensively determining the filling proportion of high-maturity crude oil in crude oil with mixed sources. The method comprises the following steps: determining the concentration Cx of adamantane compounds in the mixed source crude oil; respectively identifying the sources of the crude oil with different maturity degrees in the mixed source crude oil; according to the characteristic parameters, the filling proportion of the high-maturity crude oil in the mixed source is determined, the absolute concentration C2 of adamantane is determined when the thermal evolution degree is Ro2, and the filling volume ratio of the high-maturity oil gas in the mixed source crude oil is Cx / C2. According to the method, effective identification of the high-maturity crude oil in the crude oil with different maturity mixed sources is realized for the first time, and the problem that deep oil gas contribution is difficult to find in the past is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas field exploration, and relates to a method for comprehensively determining the charging ratio of highly mature crude oil in mixed-source crude oil. Background Art

[0002] Oil and gas resources are the basis of oil and gas exploration. Clearly defining oil and gas resources at different depths is an important issue in the selection of oil and gas exploration directions. Among them, accurately identifying the composition and source of oil and gas is the key issue in oil and gas resource calculation. During the burial process of source rocks, with the change of burial depth, low-mature to mature crude oil (Ro < 1.0%) can be formed in the middle and shallow layers, and highly mature crude oil (Ro > 1.0%) can be formed in the deep layers. In recent years, for single-source crude oil, identification technologies for the source of oil and gas based on biomarker compounds have been developed. By the relative ratios of the contents of several characteristic compounds, the environment of crude oil generation and the composition of the parent material source are clarified, so as to effectively identify the source of conventional low-mature to mature crude oil. For highly mature crude oil, due to the low thermal stability of biomarker compounds, they lose their indicative significance in highly mature crude oil, and the identification of the source of highly mature oil and gas cannot be carried out. At the same time, with the increase in exploration intensity, it has gradually been found that in some areas, due to the presence of multiple sets of source rocks and multiple stages of hydrocarbon generation and expulsion processes, the oil and gas generated by deeply buried highly evolved source rocks are mixed with low-mature to mature crude oil in the middle and shallow layers. The content of biomarker compounds in low-mature to mature crude oil is high, while the content of biomarker compounds in deeply buried highly mature crude oil is low. Therefore, the biomarker compounds in the mixed crude oil show the characteristics of medium- and low-mature crude oil. Therefore, in the identification of the source of oil and gas, the contribution of deeply buried highly mature oil and gas is often ignored, resulting in deviations in the identification of oil and gas resource quantities. This affects the understanding of the oil and gas exploration prospects in this area and the selection of oil and gas exploration directions.

[0003] In response to the above problems, exploration researchers have carried out research work in relevant aspects, mainly focusing on the effective identification of highly mature oil and gas. CN109557191A discloses a method for discriminating the parent source of highly mature crude oil, which includes the following steps: 1) Utilize the relationship between the methylphenanthrene index (MPI) of phenanthrene series compounds in the extract of source rocks and the vitrinite reflectance Ro; 2) Utilize the relationship between the methylphenanthrene index MPI of phenanthrene series compounds in crude oil and the maturity Rc of the crude oil to calculate Rc; 3) Establish the variation relationship between the vitrinite reflectance of source rocks in different horizons and the geological history period; 4) Utilize Rc in step 2) and the variation relationship between the vitrinite reflectance and the geological history period determined in step 3) to infer the source horizon and hydrocarbon accumulation time of the crude oil. Compared with the conventional method of determining the maturity of crude oil through sterane isomerization parameters (the ratio of the relative contents of two biomarker compounds), the phenanthrene series compounds have stronger thermal stability and better characterization effects on crude oil with a higher degree of evolution and maturity. However, when the maturity of the crude oil reaches Ro > 1.1%, the phenanthrene series compounds will undergo thickening reactions, and the evolution law of characteristic compounds will change, resulting in limitations in its applicability. At the same time, only using phenanthrene series compounds and adamantane compounds can only identify highly mature crude oil from a single source. When highly mature crude oil is mixed with low-mature to mature crude oil, the concentrations of phenanthrene series compounds in the two types of crude oil are similar, and the phenanthrene series compounds in highly mature crude oil are interfered by the phenanthrene series compounds in low-mature to mature crude oil, resulting in the loss of indicative significance of the phenanthrene series compounds in the mixed crude oil. Therefore, it is impossible to identify highly mature crude oil in the mixed crude oil through phenanthrene series compounds, and it is thus difficult to quantitatively determine the proportion of highly mature crude oil in the mixed-source crude oil.

[0004] Therefore, research on adamantane compounds with higher thermal stability has been carried out. CN110412144B discloses a method for determining the maturity of source rocks, which includes: (1) Using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry to identify and quantitatively analyze ethyl noradamantane compounds in the bitumen sample extracted from the source rock sample; (2) According to the identification and quantitative analysis results obtained in step (1), obtain the relative content of ethyl-substituted ethyl noradamantane in ethyl noradamantane compounds; (3) Compare the relative content obtained in step (2) with the relative content of ethyl-substituted ethyl noradamantane in ethyl noradamantane compounds in source rock samples with known maturity to determine the maturity of the target source rock.

[0005] At present, this method can accurately detect adamantane compounds in deep hydrocarbon source rocks and crude oils. By the different relative contents of different adamantane monomers and combined with the current applications of adamantane compounds in the deep layer, the identification of deep hydrocarbon source rocks and highly mature crude oils can be preliminarily realized. However, the above-mentioned patent research method mainly realizes the effective identification of a single highly mature crude oil through the ratio of relative compound contents. How to identify the charging ratio of highly mature crude oils still cannot be effectively solved.

[0006] Based on the current research progress, if we want to accurately determine the charging ratio of highly mature crude oils in mixed-source crude oils, we first need to clarify the concentration evolution laws of biomarker compounds and characteristic compounds such as adamantanes in crude oils with different evolutionary maturities, determine the mutual interference relationships during the mixing process. On this basis, by using effective parameters to identify the sources and characteristics of crude oils, can we effectively identify the accurate determination of the charging ratio of highly mature crude oils in mixed-source crude oils.

[0007] In view of this, effectively identifying the charging ratio of highly mature crude oils in mixed-source crude oils and clearly identifying the effective identification of the sources of highly mature oil and gas can achieve the accurate calculation of oil and gas resources at different depths, clarify the regional oil and gas exploration prospects and the selection of oil and gas exploration directions, which are key problems that need to be solved urgently. Summary of the Invention

[0008] The main object of the present invention is to provide a method for comprehensively determining the charging ratio of highly mature crude oils in mixed-source crude oils. The present invention can accurately identify the charging ratios and maturities of highly mature crude oils and medium- and low-maturity crude oils in mixed-source crude oils.

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

[0010] The present invention provides a method for comprehensively determining the charging ratio of highly mature crude oils in mixed-source crude oils, and the method includes the following steps:

[0011] Step 1. Determine the concentrations of sterane characteristic compounds and adamantane characteristic compounds in the crude oil to determine the concentration C of adamantane compounds in the mixed-source crude oil x ;

[0012] Step 2. Respectively identify the sources of crude oils with different maturities in the mixed-source crude oil: By determining the sterane characteristic compound parameters in the hydrocarbon source rock related to the low-maturity crude oil in the crude oil, determine the thermal evolution equivalent maturity Ro1 of the low-mature crude oil in the mixed-source crude oil; By determining the adamantane maturity parameter in the hydrocarbon source rock related to the highly mature crude oil in the crude oil, determine the thermal evolution degree Ro2 of the crude oil.

[0013] Step 3. Determine the charging ratio of high-maturity crude oil in the mixed source based on characteristic parameters: Determine the absolute concentration C2 of adamantane at the thermal evolution degree of Ro2, then the charging volume ratio of high-maturity oil and gas in the mixed-source crude oil is: C x / C2.

[0014] Further, in Step 1, when the sterane compound concentration is higher than 1000 μg / g and the adamantane concentration is higher than 200 μg / g, it indicates that this type of crude oil is a mixture of high-maturity crude oil and medium-low maturity crude oil.

[0015] Further, use comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry method to analyze the concentration of adamantane compounds;

[0016] The analysis conditions are as follows: Use a DB-petro column, 50 m, 0.2 mm i.d., 0.5 μm, as the 1D column; Select RESTEK-Rix, 2 m, 0.15 mm i.d., 0.15 μm, as the 2D column;

[0017] The DB-petro column is heated to 280 - 300 °C at a rate of 4 - 5 °C / min and isothermally maintained for 30 - 50 minutes, and the RESTEK-Rix column is heated to 310 - 350 °C at a rate of 4 - 5 °C / min and isothermally maintained for 30 - 50 minutes; Select the split mode, the split ratio is 50 - 100:1, the inlet temperature is 280 - 300 °C, the flow rate of inert gas as the carrier gas is 1.5 - 2.0 ml / min, the ionization energy is 65 - 70 eV, the ion source temperature is 240 - 280 °C, the acquisition rate is 100 - 150 spectra / second, and the mass scanning range is 40 - 600 μm.

[0018] Further, in Step 2, by analyzing the characteristic compound parameters of steranes in the mixed-source crude oil and comparing them with the characteristic biomarker compounds of the source rocks in the adjacent sags, determine the source of the low-maturity crude oil in the crude oil; Determine the source rocks related to the low-maturity crude oil in the crude oil; Establish the relationship between the concentrations of sterane compounds and adamantane compounds in the source rocks and the maturity of the crude oil; Determine the thermal evolution equivalent maturity Ro1 of the low-maturity crude oil in the mixed-source oil through the characteristic compound parameters of steranes.

[0019] Further, determine the thermal evolution equivalent maturity Ro1 of the low-maturity crude oil in the mixed-source oil through the characteristic compound parameters of steranes, and the Ro1 is expressed by the following formula:

[0020] When Ro < 0.4, Ro1 = -2 / (C / 13000) + 1.37

[0021] When 0.4 < Ro < 1.0, Ro1 = -0.5 / (C / 13000) + 0.95

[0022] C: Concentration of sterane compounds (μg / g).

[0023] Furthermore, in step 2, the lithological characteristics of the source rock related to high-maturity crude oil are determined by the relative content of dimethylbicycloalkanes in the mixed-source crude oil; the source rock related to the high-maturity crude oil in the crude oil is determined by comprehensively considering the burial depth and lithological characteristics; a relationship diagram between the methylbicycloalkane parameters and the burial depth of the source rock related to the high-maturity crude oil in the deep layer where the source rock related to the low-maturity crude oil in the crude oil is located is established; the burial depth of the source rock related to the high-maturity crude oil in the crude oil is determined according to the content of methylbicycloalkanes in the mixed-source crude oil, and the thermal evolution degree Ro2 of the crude oil is determined by the adamantane maturity parameter in the crude oil.

[0024] Furthermore, the dimethylbicycloalkane series compounds include 4,9-dimethylbicycloalkane, 4,8-dimethylbicycloalkane, and 3,4-dimethylbicycloalkane.

[0025] Furthermore, the methylbicycloalkanes include 1-methylbicycloalkane, 2-methylbicycloalkane, and 4-methylbicycloalkane.

[0026] Furthermore, the relationship model between the methylbicycloalkane parameter and the burial depth of the source rock is:

[0027] h = alnMDI - b

[0028] h: Depth (km); MDI = 100 × chromatographic peak area of 4-methylbicycloalkane / (chromatographic peak area of 1-methylbicycloalkane + chromatographic peak area of 2-methylbicycloalkane + chromatographic peak area of 4-methylbicycloalkane); a, b are fitting parameters.

[0029] Furthermore, the relationship model for determining the thermal evolution degree Ro2 of the crude oil by the adamantane maturity parameter in the crude oil is:

[0030] Ro2 = a1MDI + b1;

[0031] MDI = 100 × chromatographic peak area of 4-methylbicycloalkane / (chromatographic peak area of 1-methylbicycloalkane + chromatographic peak area of 2-methylbicycloalkane + chromatographic peak area of 4-methylbicycloalkane); a1, b1 are fitting parameters.

[0032] In the research of the present invention, it is found that in the medium - low maturity area (Ro < 0.8), the content of biomarker compounds is relatively high while the content of adamantanes is extremely low. When high - maturity crude oil is mixed with medium - low maturity crude oil, the characteristics of biomarker compounds in the mixed - source oil are similar to those of the medium - low maturity oil source. Therefore, the research on medium - low maturity crude oil can be carried out through the biomarker compounds in the mixed - source oil. In the high - maturity area (Ro > 1.0), the content of biomarker compounds is low and the content of adamantanes is relatively high. At this time, the characteristics of adamantanes in the mixed - source oil represent the characteristics of high - maturity crude oil, and the research on high - maturity crude oil in the mixed - source crude oil can be carried out through the characteristics of adamantane compounds.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] The prior art mainly identifies the source of oil and gas through biomarker compounds (such as sterane compounds, etc.). Based on the ink - bottle effect, due to the low concentration of biomarker compounds in high - maturity crude oil, its contribution is often ignored. The present invention accurately measures the concentrations of biomarker compounds and adamantanes, and establishes relevant identification methods and related evolution laws. Compared with the prior art, it has the following technical advantages:

[0035] The present invention realizes the effective identification of high - maturity crude oil in mixed - source crude oil with different maturities for the first time, overcoming the problem that it is difficult to discover the contribution of deep - layer oil and gas in the past;

[0036] The present invention establishes a method for identifying the source of high - maturity crude oil in continental lacustrine basins based on adamantane parameters for the first time, and clarifies the identification of effective deep - layer hydrocarbon source rocks;

[0037] The present invention clarifies the co - evolution law of adamantane concentration and biomarker compounds for the first time, and establishes relevant quantitative formulas;

[0038] The present invention realizes a calculation method for the mixing ratio of high - maturity crude oil in mixed - source crude oil for the first time, clarifies the resource potential of deep - layer hydrocarbon source rocks, and establishes a calculation method for the mixing ratio of high - maturity crude oil with universality through a normalization method.

[0039] The method of the present invention can accurately identify the injection ratio and degree of high - maturity crude oil in crude oil with different maturities. At the same time, the method of the present invention has excellent applicability to crude oils in different regions. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is the variation curve of adamantane compounds and sterane compounds with maturity in source rock B described in Example 2;

[0041] Figure 2 It is the relationship between methyl - bis - adamantane parameters and the burial depth of source rock described in Example 2;

[0042] Figure 3 For the relationship between the parameters of methylbisdiamantane described in Example 2 and the maturity of crude oil;

[0043] Figure 4 For the curve of the concentration of diamantane compounds in source rock C changing with maturity as described in Example 2.

[0044] Figure 5 For the sterane biomarker compound diagram of low-maturity crude oil as described in Example 3;

[0045] Figure 6 For the analysis diagram of diamantane compounds in high-maturity crude oil as described in Example 3. Specific embodiments

[0046] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0047] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and "including" are used in this specification, they indicate the presence of features, steps, operations, and their combinations.

[0048] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with specific embodiments. The following embodiments of the present invention have fully disclosed the technical solution. Determining the source of low-maturity crude oil in mixed-source crude oil through sterane characteristic compound parameters and clarifying the source rock B related to it are all prior arts.

[0049] Example 1

[0050] A method for comprehensively determining the filling ratio of high-maturity crude oil in mixed-source crude oil, the method comprising the following steps:

[0051] Step (1) In the mixed-source crude oil, deuterated sterane compounds and deuterated diamantane compounds are added to accurately measure the concentrations of sterane compounds, characteristic sterane compounds, diamantane compounds, and diamantane characteristic compounds. Through analysis and testing, the concentration C of diamantane compounds in the mixed-source oil can be obtained x .

[0052] Accurate analysis of adamantane compounds using comprehensive two-dimensional chromatography - time-of-flight mass spectrometry; For GC-GC analysis, a DB-petro column (50 m, 0.2 mm i.d., 0.5 μm) was used as the 1D column, and RESTEK-Rix (2 m, 0.15 mm i.d., 0.15 μm) was selected as the 2D column. The DB-petro column was heated to 300 °C at a rate of 4 °C / min and held isothermally for 50 minutes, and the RESTEK-Rix column was heated to 310 °C at a rate of 4 °C / min and held isothermally for 50 minutes. The split mode was selected, the split ratio was 100:1, the injection port temperature was 300 °C, the flow rate of helium as the carrier gas was 1.5 ml / min, the ionization energy was 70 eV, the ion source temperature was 240 °C, the acquisition rate was 100 spectra / second, and the mass scan range was 40 - 600 μm.

[0053] According to the concentrations of characteristic compounds in the oil source, the oil and gas characteristics are determined. When the concentration of sterane compounds is higher than 1000 μg / g and the concentration of adamantane is higher than 200 μg / g, it indicates that this type of crude oil is a mixture of high-maturity crude oil and medium-low maturity crude oil.

[0054] In step (2), through the parameters of sterane characteristic compounds and comparison with the characteristic biomarker compounds of the source rocks in adjacent sags, the source of the low-maturity crude oil in the mixed-source crude oil is clarified, and the source rock B related to it is identified.

[0055] In step (3), the relationship between the concentrations of sterane compounds and adamantane compounds in source rock B and the maturity is established.

[0056] Through the parameters of sterane characteristic compounds, the thermal evolution equivalent maturity Ro1 of the low-maturity crude oil in the mixed-source oil is determined:

[0057] Through the parameters of sterane compounds, the thermal evolution equivalent maturity Ro1 of the low-maturity crude oil in the mixed-source oil is determined:

[0058] When Ro < 0.4, Ro1 = -2 / (C / 13000) + 1.37

[0059] When 0.4 < Ro < 1.0, Ro1 = -0.5 / (C / 13000) + 0.95

[0060] C: Concentration of alkane compounds (μg / g).

[0061] At this degree of thermal evolution, the concentration of adamantane compounds is extremely low, close to 0; indicating that its adamantane compounds are derived from high-maturity crude oil.

[0062] Step (4) determines the lithological characteristics of the source rock related to the high-maturity crude oil by mixing dimethyl diamantanes in the source crude oil. Among them, 4,9-dimethyl diamantane, 4,8-dimethyl diamantane, and 3,4-dimethyl diamantane can effectively divide the source of organic matter. The source rock C related to the high-maturity crude oil in the crude oil is determined by comprehensively considering the burial depth and lithological characteristics.

[0063] Establish a relationship diagram between the methyl diamantane parameters and the burial depth of the deep source rock C in the area where the source rock B is located:

[0064] The relationship model between the methyl diamantane parameters and the burial depth of the source rock is:

[0065] h = alnMDI - b

[0066] h: depth (km); MDI = 100 × chromatographic peak area of 4-methyl diamantane / (chromatographic peak area of 1-methyl diamantane + chromatographic peak area of 2-methyl diamantane + chromatographic peak area of 4-methyl diamantane); a, b are fitting parameters.

[0067] Determine the burial depth of the source rock related to the high-maturity crude oil in the crude oil according to the content of methyl diamantane in the mixed-source crude oil.

[0068] Determine the thermal evolution degree Ro2 of the crude oil through the adamantane maturity parameters in the mixed-source crude oil;

[0069] Ro2 = a1MDI + b1;

[0070] MDI = 100 × chromatographic peak area of 4-methyl diamantane / (chromatographic peak area of 1-methyl diamantane + chromatographic peak area of 2-methyl diamantane + chromatographic peak area of 4-methyl diamantane);

[0071] a1, b1 are fitting parameters.

[0072] Step (5) establishes the relationship between the concentration of adamantane compounds and the maturity in the source rock C, clarifies the absolute concentration C2 of adamantane when the thermal evolution degree is Ro2, and indicates that the concentration of adamantane in the high-maturity crude oil is also C2. Then the injection volume ratio of the high-maturity oil and gas in the mixed-source crude oil is: C x / C2.

[0073] Example 2

[0074] Taking a certain mixed-source crude oil as an example, the method for comprehensively determining the injection ratio of high-maturity crude oil in the mixed-source crude oil includes the following steps:

[0075] Step (1): Add deuterated steranes and deuterated adamantanes to the crude oil of mixed sources to accurately measure the concentrations of steranes, characteristic steranes, adamantanes, and adamantane characteristic compounds. Through analysis and testing, the concentration C of adamantanes in the mixed-source oil can be obtained. x .

[0076] Adopt comprehensive two-dimensional chromatography-time-of-flight mass spectrometry technology for accurate analysis of adamantanes; for GC-GC analysis, use a DB-petro column (50m, 0.2mm i.d., 0.5μm) as the 1D column, and select RESTEK-Rix (2m, 0.15mm i.d., 0.15μm) as the 2D column. The DB-petro column is heated to 300°C at a rate of 4°C / min and held isothermally for 50 minutes, and the RESTEK-Rix column is heated to 310°C at a rate of 4°C / min and held isothermally for 50 minutes. Select the split mode, with a split ratio of 100:1, an inlet temperature of 300°C, a helium flow rate as the carrier gas of 1.5ml / min, an ionization energy of 70eV, an ion source temperature of 240°C, a collection rate of 100 spectra / second, and a mass scan range of 40 - 600μm.

[0077] Based on the concentrations of characteristic compounds in the oil source, determine the oil and gas characteristics. When the concentration of steranes is higher than 1000μg / g and the concentration of adamantanes is higher than 200μg / g, it indicates that this type of crude oil is a mixture of high-maturity crude oil and medium-low maturity crude oil.

[0078] Step (2): Through the parameters of sterane characteristic compounds and comparison with the characteristic biomarker compounds of the source rocks in adjacent sags, clarify the source of the low-maturity crude oil in the mixed-source crude oil and identify the source rock B related to it.

[0079] Step (3): Establish the relationship between the concentrations of steranes and adamantanes in source rock B and maturity.

[0080] Establish the relationship between the concentration of steranes in source rock B and maturity, as Figure 1 shown.

[0081] Through the parameters of sterane characteristic compounds, determine the thermal evolution equivalent maturity Ro1 of the low-maturity crude oil in the mixed-source oil.

[0082] When Ro < 0.4, Ro1 = -2 / (C / 13000) + 1.37

[0083] When 0.4 < Ro < 1.0, Ro1 = -0.5 / (C / 13000) + 0.95

[0084] C: Concentration of steranes (μg / g).

[0085] At this degree of thermal evolution, the concentration of adamantane compounds is extremely low, approaching 0, indicating that the adamantane compounds are derived from highly mature crude oil.

[0086] Step (4) determines the lithological characteristics of the source rock related to highly mature crude oil by mixing dimethyladamantanes in the source crude oil. Among them, 4,9-dimethyladamantane, 4,8-dimethyladamantane, and 3,4-dimethyladamantane can effectively distinguish the sources of organic matter. The source rock C related to the highly mature crude oil in the crude oil is determined by integrating the burial depth and lithological characteristics.

[0087] Establish a relationship diagram between the methyladamantane parameters and the burial depth of the deep source rock C in the area where source rock B is located, as Figure 2 shown:

[0088] The relationship model between the methyladamantane parameters and the burial depth of the source rock is:

[0089] h = 1.92lnMDI - 2.328

[0090] h: depth (km); MDI = 100 × chromatographic peak area of 4-methyladamantane / (chromatographic peak area of 1-methyladamantane + chromatographic peak area of 2-methyladamantane + chromatographic peak area of 4-methyladamantane).

[0091] Determine the burial depth of the source rock related to the highly mature crude oil in the crude oil according to the content of methyladamantanes in the mixed-source crude oil.

[0092] Determine the degree of thermal evolution Ro2 of the crude oil through the adamantane maturity parameters in the mixed-source crude oil, as Figure 3 shown;

[0093] Ro2 = 0.0317MDI + 0.1;

[0094] MDI = 100 × chromatographic peak area of 4-methyladamantane / (chromatographic peak area of 1-methyladamantane + chromatographic peak area of 2-methyladamantane + chromatographic peak area of 4-methyladamantane);

[0095] Step (5) establishes the relationship between the concentration of adamantane compounds and the maturity in source rock C, as Figure 4 shown:

[0096] When Ro > 1.3, Ro = C / (3 × 10 4 ) + 1.37

[0097] When 0.8 < Ro < 1.3, Ro = 0.089ln C + 0.46

[0098] C: adamantane concentration (μg / g)

[0099] Define the absolute concentration C2 of adamantane at the thermal evolution degree of Ro2. It shows that the concentration of adamantane in the highly mature crude oil is also C2. Then the filling volume ratio of the highly mature oil and gas in the mixed-source crude oil is: C x / C2.

[0100] Example 3

[0101] Take 15 ml of highly mature crude oil with a thermal evolution degree of Ro = 1.4 discovered in this area and mix it with 5 ml of low-mature crude oil with a thermal evolution degree of Ro approximately 0.5.

[0102] The characteristics of sterane biomarker compounds in the low-mature crude oil are as Figure 5 shown, and the geochemical characteristics of the highly mature crude oil are as Figure 6 shown.

[0103] Step (1) In the mixed-source crude oil, add deuterated sterane compounds (5α-cholestane-D4) and deuterated adamantane compounds (adamantane-D16). Through analysis and testing, the concentration C x of adamantane compounds in the mixed-source oil can be obtained as 678.5 μg / g, and the concentration of sterane compounds is 2741.6 μg / g, indicating that this type of crude oil is a mixture of highly mature crude oil and medium-low mature crude oil.

[0104] Step (2) In the mixed crude oil, the biomarker compounds have obvious phytane preference and high gammacerane content, indicating that this crude oil is derived from the source rock B in a saline-reducing sedimentary environment. Combining the burial depth characteristics of the crude oil in this area, it shows that this crude oil is derived from the source rock with a thermal evolution degree at a burial depth of 3000 meters.

[0105] Step (3) Analyze the adamantane compounds in the source rocks with similar current burial depths. No adamantane compounds are found in the samples shallower than 3750 meters, indicating that the crude oil in the mixed source is from highly mature crude oil.

[0106] Step (4) Analyze the parameters of dimethylbicyclo[3.3.1]nonanes in the mixed-source crude oil. The relative proportions of 4,9-dimethylbicyclo[3.3.1]nonane, 4,8-dimethylbicyclo[3.3.1]nonane, and 3,4-dimethylbicyclo[3.3.1]nonane are 52%:26%:22%, indicating that this source rock is from a deep source rock with a saline lake sedimentary environment. Through the analysis of the parameters of methylbicyclo[3.3.1]nonanes, its corresponding thermal evolution degree is 1.4, and its corresponding burial depth is 4300 meters. Considering the burial depth of the source rock and the lithology of the source rock, the highly mature crude oil is from the deep source rock C with a saline lake sedimentary environment.

[0107] The general burial depth of this set of source rocks is more than 4,300 meters. By analyzing this set of source rocks, the concentration of sterane compounds in the source rocks is lower than 10 μg / g, indicating that the sterane compounds in the mixed-source crude oil are mainly contributed by low-maturity crude oil.

[0108] In step (5), in the mixed crude oil, the adamantane compounds are derived from deep high-maturity crude oil. The concentration C2 of adamantane compounds in the source rocks at this depth is 925.2 μg / g. According to the method established in this patent, the proportion of high-maturity crude oil is 73.3%.

[0109] The proportion of the crude oil source identified by the method established in the present invention is the same as that of the prepared crude oil, indicating that the method described in the present invention has good accuracy.

[0110] However, through the prior art, the maturity of this crude oil is mainly identified by the sterane isomerization parameter. In low-maturity crude oil and mixed-source crude oil, the sterane isomerization parameter C / (C + D) is 0.35.

[0111] Where C represents the sum of the chromatographic peak areas of 24-ethyl, 5α, 14α, 17α-C 29 , cholestane (20S); D represents the sum of the chromatographic peak areas of 24-ethyl, 5α, 14α, 17α-C 29 , cholestane (20R).

[0112] According to the sterane isomerization parameter, both low-maturity crude oil and mixed crude oil are judged as single low-evolution crude oil, and the effective identification of high-maturity crude oil in the mixed source cannot be achieved.

[0113] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for comprehensively determining the injection ratio of highly mature crude oil in mixed-source crude oil, characterized in that, It includes the following steps: Step 1. Determine the concentrations of sterane characteristic compounds and adamantane characteristic compounds in the crude oil, and determine the concentration C of adamantane compounds in the mixed-source crude oil. x ; Step 2. Identify the sources of crude oils with different maturities in the mixed-source crude oil respectively: Determine the equivalent thermal maturity Ro1 of the low-maturity crude oil in the mixed-source crude oil by measuring the sterane characteristic compound parameters in the source rock related to the low-maturity crude oil in the crude oil; Determine the thermal evolution degree Ro2 of the crude oil by determining the adamantane maturity parameters in the source rock related to the high-maturity crude oil in the crude oil; Step 3. Determine the charging ratio of the high-maturity crude oil in the mixed source according to the characteristic parameters: Determine the absolute concentration C2 of adamantane at the thermal evolution degree of Ro2, then the charging volume ratio of the high-maturity oil and gas in the mixed-source crude oil is: C x / C2.

2. The method according to claim 1, wherein In step 1, when the concentration of sterane compounds is higher than 1000 μg / g and the concentration of adamantane is higher than 200 μg / g, it indicates that this type of crude oil is a mixture of high-maturity crude oil and medium-low maturity crude oil.

3. The method according to claim 1, wherein Analyze the concentration of adamantane compounds by comprehensive two-dimensional chromatography-time-of-flight mass spectrometry method; The analysis conditions are as follows: Use a DB-petro column, 50 m, 0.2 mm i.d., 0.5 μm, as the 1D column; Select RESTEK-Rix, 2 m, 0.15 mm i.d., 0.15 μm, as the 2D column; The DB-petro column is heated to 280 - 300 °C at a rate of 4 - 5 °C / min and isothermally maintained for 30 - 50 minutes, and the RESTEK-Rix column is heated to 310 - 350 °C at a rate of 4 - 5 °C / min and isothermally maintained for 30 - 50 minutes; Select the split mode, the split ratio is 50 - 100:1, the injection port temperature is 280 - 300 °C, the flow rate of inert gas as the carrier gas is 1.5 - 2.0 ml / min, the ionization energy is 65 - 70 eV, the ion source temperature is 240 - 280 °C, the acquisition rate is 100 - 150 spectra / second, and the mass scanning range is 40 - 600 μm.

4. The method according to claim 1, characterized in that, In step 2, by analyzing the parameters of sterane characteristic compounds in the mixed-source crude oil and comparing them with the characteristic biomarker compounds of the source rocks in the adjacent sag, determine the source of the low-maturity crude oil in the crude oil; Determine the source rocks related to the low-maturity crude oil in the crude oil; Establish the relationship between the concentrations of sterane compounds and adamantane compounds in the source rocks and the maturity of the crude oil; Determine the thermal evolution equivalent maturity Ro1 of the low-maturity crude oil in the mixed-source oil through the parameters of sterane characteristic compounds.

5. The method according to claim 1 or 4, characterized in that, Determine the thermal evolution equivalent maturity Ro1 of the low-maturity crude oil in the mixed-source oil through the parameters of sterane compounds: When Ro < 0.4, Ro1 = -2 / (C / 13000) + 1.37 When 0.4 < Ro < 1.0, Ro1 = -0.5 / (C / 13000) + 0.95 C: Concentration of sterane compounds (μg / g).

6. The method according to claim 1, wherein In step 2, through the relative content of dimethylbicyclo[2.2.2]octane series compounds in the mixed-source crude oil, determine the lithological characteristics of the source rocks related to the high-maturity crude oil; Comprehensively determine the source rocks related to the high-maturity crude oil in the crude oil based on the burial depth and lithological characteristics; Establish a relationship diagram between the parameters of methylbicyclo[2.2.2]octane in the deep layer where the source rocks related to the low-maturity crude oil in the crude oil are located and the burial depth of the source rocks related to the high-maturity crude oil in the crude oil; Determine the burial depth of the source rocks related to the high-maturity crude oil in the crude oil according to the content of methylbicyclo[2.2.2]octane in the mixed-source crude oil, and determine the thermal evolution degree Ro2 of the crude oil through the maturity parameters of adamantane in the crude oil.

7. The method according to claim 6, wherein The dimethylbicyclo[2.2.2]octane series compounds include 4,9-dimethylbicyclo[2.2.2]octane, 4,8-dimethylbicyclo[2.2.2]octane, and 3,4-dimethylbicyclo[2.2.2]octane.

8. The method according to claim 6, wherein The methylbicyclo[2.2.2]octane includes 1-methylbicyclo[2.2.2]octane, 2-methylbicyclo[2.2.2]octane, and 4-methylbicyclo[2.2.2]octane.

9. The method according to claim 6, characterized in that, The relationship model between the methylbiscadamane parameter and the burial depth of the hydrocarbon source rock is as follows: h = alnMDI - b h: depth (km); MDI = 100 × chromatographic peak area of 4-methylbiscadamane / (chromatographic peak area of 1-methylbiscadamane + chromatographic peak area of 2-methylbiscadamane + chromatographic peak area of 4-methylbiscadamane); a and b are fitting parameters.

10. The method according to claim 1 or 6, characterized in that The relationship model for determining the thermal evolution degree Ro2 of crude oil through the adamantane maturity parameter in crude oil is as follows: Ro2 = a1MDI + b1; MDI = 100 × chromatographic peak area of 4-methylbiscadamane / (chromatographic peak area of 1-methylbiscadamane + chromatographic peak area of 2-methylbiscadamane + chromatographic peak area of 4-methylbiscadamane); a1 and b1 are fitting parameters.

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