Method for calculating coal rock maturity by simulating crude oil n-alkanes based on hydrocarbon generation heat

Abstract

The invention discloses a method for calculating coal rock maturity by simulating crude oil n-alkanes based on hydrocarbon generation heat. The method comprises the following steps: S1, collecting a rock core sample or a field outcrop sample; s2, performing a gold tube closed system hydrocarbon generation thermal simulation experiment on the sample, and collecting liquid hydrocarbon products generated at different temperature points; s3, performing gas chromatographic analysis on the liquid hydrocarbon product; s4, calculating the equivalent Ro of each temperature point, counting the peak area value of the n-alkanes at each temperature point, and selecting the n-alkanes with the carbon number of C6-C17 at each temperature point to calculate the sum of the peak areas; s5, fitting to obtain a function relation between the equivalent Ro and the sum of the peak areas of the n-alkanes; and S6, taking crude oil samples of the same hydrocarbon source rock source in the research area, measuring the n-alkane peak area of the crude oil, substituting peak area data into the function relation established in the step S5, and calculating to obtain the equivalent Ro of the crude oil samples. The method is suitable for quantitative calculation of crude oil maturity in all thermal evolution stages, and has important significance for oil-gas exploration.

Description

Technical Field

[0001] This invention relates to the field of geological exploration technology, and in particular to a method for calculating coal and rock maturity based on hydrocarbon generation heat simulation of crude oil n-alkane. Background Technology

[0002] Crude oil maturity is a crucial bridge in studying the origin and evolution of oil and gas reservoirs, its importance spanning the entire chain from early exploration and resource assessment to development and utilization and geological research. Crude oil maturity refers to the degree to which organic matter has gradually transformed into petroleum through thermal evolution and other processes during geological history. Maturity is one of the key parameters for oil source correlation, allowing for the tracing of the source material origin of crude oil and the evaluation of crude oil quality.

[0003] Terpenes and steranes are cyclic hydrocarbons with stable molecular structures formed from the chemical transformation of parent material during diagenesis and thermal evolution of sedimentary organic matter. They play a crucial role in maturity assessment. Among them, the C64 in terpenes... 30 The α- and β-isomers of hydrogen atoms at positions 17 and 21 in hopane and C 31 The S- and R-configuration isomers of the hopane side chain at carbon atom 22 are both affected by temperature during burial depth and exhibit a clear evolutionary pattern. As maturity gradually increases, C... 30 The unstable βα configuration 17β(H),21α(H)-hopane in hopane gradually transforms into the stable αβ configuration 17α(H),21β(H)-hopane. C 31 In hopane, the unstable R configuration at the 22nd carbon atom gradually transforms into the S configuration, therefore αβ-C can be used. 30 hopane / βα-C 30 hopane ratio and C 31 The 22S / (22S+22R) ratio of hopane is used to characterize crude oil maturity. Additionally, the C content in sterane compounds... 29 The S and R configuration isomers of the 20th carbon atom in a sterane molecule, as well as the configuration isomers of the hydrogen atoms at positions 5, 14, and 17, can all be used to assess changes in crude oil maturity. As maturity increases, the R configuration of the 20th carbon atom gradually transforms into the S configuration; the configurations of the hydrogen atoms at positions 5, 14, and 17 gradually transform from the ααα configuration to the αββ configuration. These values ​​no longer change after the early stages of high maturity; therefore, Cm can be used as a criterion. 29 sterane 20S / (20S+20R) and C 29The ββ / (αα+ββ) ratio of steranes can be used to some extent to identify crude oil maturity. In addition, n-alkanes with straight-chain skeletons and fully saturated bond structures can also serve as chemical fingerprints of crude oil. As maturity increases, n-alkanes gradually transform into shorter chains, the odd-even carbon dominance remaining from biological sources gradually disappears, and the relative content ratios within specific carbon number ranges change accordingly. The Carbon Dominance Index (CPI) and Odd-Even Dominance Ratio (OEP) both characterize crude oil maturity by quantifying the difference in the content of odd and even carbons in n-alkanes; as maturity increases, the CPI and OEP values ​​gradually approach 1. The above-mentioned biomarker compounds are applicable to the low-maturity to mature stage. However, for hydrocarbon products in the high-maturity to over-mature stage, the n-alkanes, terpenes, and steranes in crude oil will exhibit distortion, leading to errors in the calculation of crude oil maturity.

[0004] Adamantane in crude oil is a class of polycyclic alkanes with a rigid cage-like structure, exhibiting extremely high thermal stability and outstanding resistance to biodegradation and water washing. Studies have shown that the monoadamantane / diadamantane ratio (MDR), methyl monoadamantane index (MAI), methyl diadamantane index (MDI), and ethyl monoadamantane index (EAI) of adamantane compounds can effectively qualitatively characterize crude oil maturity. As crude oil maturity increases, the MDR ratio gradually decreases and tends to stabilize, while the MAI, MDI, and EAI indices gradually increase and tend to stabilize. However, because these adamantane characteristic parameters fluctuate greatly between the low and mature organic matter stages, errors exist in identifying the crude oil maturity at this stage. Summary of the Invention

[0005] To address the errors and drawbacks of existing methods for calculating crude oil maturity based on substances such as n-alkanes, terpenes, and adamantane compounds, and in order to quantitatively calculate crude oil maturity at different thermal evolution stages, this invention provides a method for calculating coal and petrological maturity based on hydrocarbon generation thermal simulation of crude oil n-alkanes.

[0006] The method of this invention is based on a thermal simulation experiment of hydrocarbon generation in a gold tube using low-mature organic matter samples. It analyzes the carbon number distribution characteristics of n-alkanes in crude oil at different thermal evolution stages, establishes the relationship between the carbon number distribution of n-alkanes and maturity, and quantitatively calculates the equivalent vitrinite reflectance R of crude oil. o The thermal evolution stages of crude oil were distinguished by peak area correction for different carbon numbers.

[0007] The method for calculating coal and petrological maturity based on hydrocarbon generation heat simulation of crude oil n-alkanes provided by this invention includes the following specific steps: S1. Collect immature or low-maturity core samples or field outcrop samples, crush and grind the samples, screen out powder with a particle size of 80-100 mesh and uniform particle size, and acid treat the powder to remove inorganic minerals such as carbonate rocks and silicate rocks.

[0008] S2. A thermal simulation experiment of hydrocarbon generation in a closed gold tube system was conducted using pretreated samples. Liquid hydrocarbon products generated at different temperature points were collected during the heating process.

[0009] S3. Perform gas chromatography analysis on the collected liquid hydrocarbon products to obtain the n-alkane spectrum.

[0010] S4. Calculate the equivalent R at each temperature point. o We analyzed and statistically analyzed the peak area values ​​of n-alkanes at each temperature point, and calculated the sum of the peak areas of n-alkanes with C6-C17 carbons at each temperature point.

[0011] S5. The calculated equivalent R o Plotting the graph in a Cartesian coordinate system with the sum of peak areas on the x-axis and the equivalent Ro on the y-axis, we can fit a functional relationship between the sum of the peak areas of the n-alkane and the equivalent Ro. The specific method is as follows: Based on the peak area variation trend of n-alkane at different temperature points as statistically analyzed in step S4, the peak area generally shows a trend of first gradually increasing and then decreasing as the temperature rises. The equivalent R0 at the temperature point corresponding to the point where the peak area begins to decrease is taken. o The value is used as a threshold; Using the threshold as the dividing point, in the intervals below the threshold and above the threshold, respectively, the equivalent R is used. o Using the vertical axis as the ordinate and the sum of peak areas as the horizontal axis, a graph is plotted in a rectangular coordinate system to obtain the equivalent R0. o The functional relationship between the peak area of ​​n-alkane and the total peak area of ​​n-alkane.

[0012] S6. Take crude oil samples from the same source rock within the study area, and measure the peak area data of n-alkane in the crude oil samples by gas chromatography. Calculate the sum of the peak areas of n-alkane with C6-C17 carbons, and substitute the sum of the peak areas into the equivalent R obtained in step S5. o The functional relationship between the peak areas of the crude oil sample and the sum of the peak areas of n-alkanes was used to calculate the equivalent Ri of the crude oil sample. o .

[0013] Preferably, in step S2, two samples are taken. One sample undergoes a closed-system hydrocarbon generation thermal simulation experiment in a gold tube at a heating rate of 2℃ / h, gradually increasing the temperature from 200℃ to 600℃, and collecting liquid hydrocarbon products at equal time intervals within the temperature range of 300℃ to 600℃. The other sample undergoes the same simulation experiment with a heating rate of 20℃ / h. The collected liquid hydrocarbon products are analyzed by gas chromatography to obtain n-alkane chromatograms.

[0014] In step S5, for the experimental data with a heating rate of 2℃ / h, two equivalent R values ​​are fitted to obtain... oThe functional relationship between the peak areas and the sum of the n-alkane peak areas is given by equations 1 and 2. For experimental data with a heating rate of 20℃ / h, two equivalent R-values ​​are obtained through fitting. o The functional relationship between the peak area of ​​n-alkane and the total peak area is shown in Equations 3 and 4.

[0015] The specific method for step S6 is as follows: (1) Perform gas chromatography analysis on crude oil samples to obtain the peak area data of n-alkane in crude oil samples, and calculate the total peak area of ​​n-alkane with C6-C17 carbons. (2) Based on the distribution range of peak area values, determine whether to choose Equation 1 or Equation 2, substitute the sum of the peak areas of n-alkanes with C6-C17 carbons calculated into the chosen functional relationship, and calculate the equivalent R of the crude oil sample. o ; (3) Based on the distribution range of peak area values, determine whether to choose Equation 3 or Equation 4, substitute the sum of the peak areas of n-alkanes with C6-C17 carbons calculated into the chosen functional relationship, and calculate the equivalent R of the crude oil sample. o ; (4) The equivalent R of the crude oil sample calculated in steps (2) and (3) o The average value is calculated to obtain the final equivalent R for the crude oil sample. o .

[0016] Compared with the prior art, the advantages of the present invention are: (1) This invention utilizes thermal simulation of hydrocarbon generation in gold tubes and chromatographic analysis of n-alkane at different thermal evolution stages to calculate the crude oil maturity of reservoirs. It can calculate the crude oil maturity at different thermal evolution stages from the same set of source rocks. This solves the problem that current methods cannot calculate the crude oil maturity of the entire thermal evolution stage.

[0017] (2) The method of the present invention unifies the geochemical parameters used to calculate the maturity of crude oil at different thermal evolution stages, simplifies the calculation method, can quickly and effectively calculate the maturity of crude oil, and the calculation results are highly reliable.

[0018] (3) This method is applicable to the quantitative calculation of crude oil maturity in all thermal evolution stages. Compared with existing methods, it is more universal and can be widely used. It is of great significance to oil and gas exploration.

[0019] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0020] Figure 1 This is a flowchart of the method for calculating coal and rock maturity based on hydrocarbon generation heat simulation of crude oil n-alkane.

[0021] Figure 2 The above are gas chromatograms of liquid hydrocarbon products at different temperature points measured under heating rates of 2℃ / h and 20℃ / h in the examples.

[0022] Figure 3 This is a bar chart showing the absolute difference in the area of ​​each carbon number peak under adjacent EasyRo.

[0023] Figure 4 This is a bar chart showing the absolute difference in the area of ​​adjacent EasyRo peaks at different carbon numbers when the heating rate is 2℃ / h.

[0024] Figure 5 This is a bar chart showing the peak shapes of n-alkanes before and after the maturity threshold at the two heating rates in the examples.

[0025] Figure 6 This is a curve showing the fitting of the peak area of ​​n-alkane before and after the maturity threshold obtained in the example with the equivalent Ro.

[0026] Figure 7 This is a histogram showing the calculated Ro and the measured Ro in the examples. Detailed Implementation

[0027] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0028] like Figure 1 As shown, the method for calculating coal and petrological maturity based on hydrocarbon generation heat simulation of crude oil n-alkane, according to the present invention, includes the following specific steps: (1) Two low-maturity coal samples were collected from No. 8 coal at the Heidaigou open-pit coal mine in the Ordos Basin, referred to as Sample A and Sample B. Sample A and Sample B were pretreated respectively. Specifically, the samples were crushed and ground, and powder with a particle size of 80-100 mesh and uniform particle size was screened through a standard sieve. The powder was added to hydrochloric acid solution (concentration 5-6 mol / L) and reacted fully at room temperature until no bubbles were visible. This was used to remove inorganic minerals such as carbonate rocks and silicate rocks.

[0029] (2) Weigh 20-200 mg of pretreated sample A powder using a balance and uniformly pack it into a gold tube. Install the experimental equipment and check the sealing of the apparatus. Then, conduct a thermal simulation experiment of hydrocarbon generation in the closed gold tube system. Set the heating rate to 2℃ / h. The experiment starts from 200℃ and gradually increases to 600℃. Record the hydrocarbon yield every 20℃ increase within the temperature range of 300 to 600℃ and collect the liquid hydrocarbon product. Collect 100 mg of liquid hydrocarbon product at each temperature point. Perform gas chromatography analysis on the liquid hydrocarbon product at different temperature points to obtain chromatograms of n-alkane under different thermal evolution degrees.

[0030] (3) Using the pretreated sample B, set the heating rate to 20℃ / h, and perform the experiment and gas chromatography analysis in the same way as in step (2).

[0031] Figure 2 These are gas chromatograms of liquid hydrocarbon products at different temperature points measured under heating rates of 2℃ / h and 20℃ / h.

[0032] (4) Calculate the equivalent R corresponding to each temperature point T. o ( (%), the relevant introduction to EasyRo can be found in the literature (Jerry J. Sweeney and Alan K. Burnham. Evaluation of a Simple Model of Vitrinite Reflectance Based on Chemical Kinetics. The American Association of Petroleum Geologists Bulletin V.74. No.10 (October 1990)). P.1559-1570. 8 Figs., 1 Table). Calculated using the dynamics software Kinetics Neo.

[0033] Analyze and statistically analyze the peak area values ​​of n-alkane at each temperature point. Under a heating rate of 20℃ / h, the equivalent Ra at different temperature points is calculated. o The peak area data of n-alkane products of (EasyRo) and liquid hydrocarbons are shown in Tables 1 and 2. The equivalent Ra at different temperature points under a heating rate of 2℃ / h... o The peak area data of n-alkane for (EasyRo, %) and liquid hydrocarbon products are shown in Tables 3 and 4.

[0034] Table 1. Peak area data of n-alkane in liquid hydrocarbon products at different temperatures under a heating rate of 20℃ / h

[0035] Table 2. Peak area data of n-alkane in liquid hydrocarbon products at different temperatures under a heating rate of 20℃ / h.

[0036] Table 3. Peak area data of n-alkane in liquid hydrocarbon products at different temperatures under a heating rate of 2℃ / h.

[0037] Table 4. Peak area data of n-alkane in liquid hydrocarbon products at different temperatures under a heating rate of 2℃ / h.

[0038] Read the peak area data of liquid n-alkanes at different temperature points and analyze adjacent R values. o The difference in absolute peak areas in the chromatogram, such as Figure 3 As shown, the absolute difference in peak area between EasyRo at 1.47% and 1.8% ranges from 2.8 to 252.2, with an average of 94.01. Therefore, using the average value as the standard, peaks with an absolute difference in peak area greater than 94 are selected as key parameters for establishing EasyRo and peak area. Analysis results show that the carbon numbers meeting the criteria are mainly distributed between C6 and C17. Therefore, peak area data of n-alkanes with C6-C17 carbon numbers are selected to establish a functional relationship between n-alkane peak area and maturity. Specifically, the sum of peak areas of n-alkanes with C6-C17 carbon numbers at each temperature point is calculated, and the relationship between the sum of peak areas and EasyRo is established. o The functional relationship.

[0039] (5) Based on the peak area data of liquid hydrocarbon n-alkane in Table 1-4 and Figure 4 It can be observed that with the increase of thermal evolution, the carbon peak content of the n-alkane spectrum of crude oil first gradually increases and then gradually decreases, where the equivalent R... o When the concentration exceeds 1.8%, the peak shape of n-alkane in crude oil begins to gradually decrease. Furthermore, according to nearby EasyR... o Peak area between Figure 3 Analysis revealed (taking a heating rate of 2℃ / h as an example) that EasyR o The largest absolute difference was found between the peak areas of 1.45% and 1.8%. Further analysis revealed that n-alkanes in EasyR... o The peak area changes relatively significantly around 1.8%, thus clarifying the equivalent R of n-alkanes. o The threshold is 1.8%.

[0040] Further integration Figure 5It can be seen that the peak areas of n-alkanes with equivalent Ro less than 1.8% and greater than 1.8% in liquid hydrocarbons are distributed as follows: when the equivalent Ro in liquid hydrocarbons is less than 1.8%, the average peak area of ​​n-alkanes is distributed between 3.26 and 154.28, with an average of 62.98, indicating a relatively high average peak area; while when the equivalent Ro in liquid hydrocarbons is greater than 1.8%, the peak area of ​​n-alkanes is mainly distributed between 0 and 14.38, with an average of 2.16, indicating a relatively low peak area.

[0041] This indicates that in a closed system, as the thermal simulation temperature increases, the content of n-alkane peaks in crude oil at the low to high maturity stages will be relatively high, while in the equivalent R... o If the concentration is greater than 1.8%, crude oil will crack and form gaseous hydrocarbons, resulting in a lack of information on the n-alkane composition of the crude oil.

[0042] like Figure 6 As shown, in the equivalent R o For intervals less than 1.8%, use the equivalent R... o The vertical axis is set to y, and the horizontal axis is the sum of the calculated peak areas of n-alkanes with C6-C17 carbon atoms. Plotting this graph in a Cartesian coordinate system yields the equivalent R-squared value. o The functional relationship between y and the sum of the peak areas of n-alkanes is given by Equation 1: y = 0.0003 × R o +0.6093, (R 2 =09157). In the equivalent R o For intervals greater than 1.8%, the equivalent R is obtained using the same method. o The functional relationship between the total peak area of ​​n-alkanes and y is given by Equation 2: y = -0.309 × Ln(R o +3.4521, (R) 2 =0.7963). This is the relationship between maturity and n-alkanes.

[0043] For data with a heating rate of 20℃ / h, the equivalent R was obtained using the same method described above. o Equivalent R less than the threshold interval o The functional relationship between the peak area of ​​n-alkane and the total peak area y (Equation 3), and the equivalent R o Equivalent R greater than the threshold interval o The functional relationship between the total peak area of ​​n-alkanes and y is given by equation (Equation 4).

[0044] (6) Hydrocarbon samples were collected from underground cores of coal seam No. 8 in three strata. The average area of ​​each carbon number peak of n-alkane was calculated to be between 15, indicating that it is a product of the high-to-over-mature stage. The calculated area of ​​the C6-C17 carbon number peaks of crude oil samples was between 4.2 and 17.35, with an average of 11.97. Therefore, the equivalent R value was used. o Equivalent R under the condition greater than 1.8%o The functional relationship between the sum of peak areas of n-alkanes and y is determined. First, the sum of peak areas for C6-C17 carbons is calculated, and then substituted into the equivalent R² value. o From the functional relationship between the total peak area of ​​n-alkanes and y, the equivalent R is calculated. o The equivalent R was calculated using the functional relationships obtained at the two heating rates. o Finally, calculate the two equivalent R values. o The average value is shown in Table 5. Figure 7 .

[0045] Core samples from three strata of coal seam #8 were collected for vitrinite reflectance analysis. The calculated vitrinite reflectance (Ro) of the organic matter in coal seam #8 ranged from 2.24% to 2.31%, with an average of 2.287%. This is comparable to the average difference of 0.055% in hydrocarbons found in crude oil (Table 5). Figure 7 The equivalent Ro error calculated using this method is 2.4%. This invention is accurate, reliable, and yields good computational results.

[0046] Table 5 Comparison of Measured Data and Calculated Data

[0047] In summary, the method of this invention mainly utilizes a closed-system hydrocarbon generation thermal simulation device (gold tube-high pressure reactor) to conduct hydrocarbon generation experiments on low-mature organic matter samples. It analyzes the peak shape changes of crude oil at different thermal evolution stages, establishes a quantitative relationship between the equivalent vitrinite reflectance of crude oil and peak shape, and uses peak area for correction. Based on existing crude oil chromatographic properties, it calculates crude oil maturity. This method is applicable to the quantitative calculation of crude oil maturity at all thermal evolution stages, exhibiting greater universality than existing methods. The calculated equivalent Ro has an error of only 7.57% compared to the measured Ro, demonstrating accuracy and reliability, and can be used to guide the exploration and development of oil and gas.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for calculating coal and petrological maturity based on hydrocarbon generation heat simulation of crude oil n-alkanes, characterized in that, Includes the following steps: S1. Collect immature or low-maturity core samples or field outcrop samples, and pre-treat the samples to remove inorganic minerals; S2. A thermal simulation experiment of hydrocarbon generation in a closed gold tube system was conducted using the pretreated sample. Liquid hydrocarbon products generated at different temperature points were collected during the heating process. S3. Perform gas chromatography analysis on the collected liquid hydrocarbon products to obtain the n-alkane spectrum; S4. Calculate the equivalent R at each temperature point. o The peak area values ​​of n-alkanes at each temperature point were analyzed and statistically analyzed, and the total peak area of ​​n-alkanes with C6-C17 carbons at each temperature point was calculated. S5. The calculated equivalent R o Plotting the graph in a rectangular coordinate system with the sum of peak areas as the x-axis and the equivalent Ro as the sum of the peak areas of n-alkanes, we can obtain a functional relationship between the equivalent Ro and the sum of the peak areas of n-alkanes. S6. Take crude oil samples from the same source rock within the study area, and measure the peak area data of n-alkane in the crude oil samples by gas chromatography. Calculate the sum of the peak areas of n-alkane with C6-C17 carbons, and substitute the sum of the peak areas into the equivalent R obtained in step S5. o The functional relationship between the peak areas of the crude oil sample and the sum of the peak areas of n-alkanes was used to calculate the equivalent Ri of the crude oil sample. o .

2. The method for calculating coal and petrological maturity based on hydrocarbon generation heat simulation of crude oil n-alkanes as described in claim 1, characterized in that, The specific method for step S5 is as follows: Based on the peak area variation trend of n-alkane at different temperature points as statistically analyzed in step S4, the peak area generally shows a trend of first gradually increasing and then decreasing as the temperature rises. The equivalent R0 at the temperature point corresponding to the point where the peak area begins to decrease is taken. o The value is used as a threshold; Using the threshold as the dividing point, in the intervals below the threshold and above the threshold, respectively, the equivalent R is used. o Using the vertical axis as the ordinate and the sum of peak areas as the horizontal axis, a graph is plotted in a rectangular coordinate system to obtain the equivalent R0. o The functional relationship between the peak area of ​​n-alkane and the total peak area of ​​n-alkane.

3. The method for calculating coal and petrological maturity based on hydrocarbon generation heat simulation of crude oil n-alkane, as described in claim 2, is characterized in that... In step S2, two samples are taken. One sample is subjected to a thermal simulation experiment of hydrocarbon generation in a closed gold tube system at a heating rate of 2℃ / h, starting from 200℃ and gradually increasing to 600℃. Liquid hydrocarbon products are collected at equal intervals in the temperature range of 300℃ to 600℃. The other sample is subjected to a thermal simulation experiment of hydrocarbon generation in a closed gold tube system by changing the heating rate to 20℃ / h.

4. The method for calculating coal and petrological maturity based on hydrocarbon generation heat simulation of crude oil n-alkanes as described in claim 3, characterized in that, In step S5, for the experimental data with a heating rate of 2℃ / h, two equivalent R values ​​are fitted to obtain... o The functional relationship between the peak areas and the sum of the n-alkane peak areas is given by equations 1 and 2. For experimental data with a heating rate of 20℃ / h, two equivalent R-values ​​are obtained through fitting. o The functional relationship between the peak area of ​​n-alkane and the total peak area is shown in Equations 3 and 4.

5. The method for calculating coal and petrological maturity based on hydrocarbon generation heat simulation of crude oil n-alkane as described in claim 4, characterized in that, The specific method for step S6 is as follows: (1) Perform gas chromatography analysis on crude oil samples to obtain the peak area data of n-alkane in crude oil samples, and calculate the total peak area of ​​n-alkane with C6-C17 carbons. (2) Based on the distribution range of peak area values, determine whether to choose Equation 1 or Equation 2, substitute the sum of the peak areas of n-alkanes with C6-C17 carbons calculated into the chosen functional relationship, and calculate the equivalent R of the crude oil sample. o ; (3) Based on the distribution range of peak area values, determine whether to choose Equation 3 or Equation 4, substitute the sum of the peak areas of n-alkanes with C6-C17 carbons calculated into the chosen functional relationship, and calculate the equivalent R of the crude oil sample. o ; (4) The equivalent R of the crude oil sample calculated in steps (2) and (3) o The average value is calculated to obtain the final equivalent R for the crude oil sample. o .

6. The method for calculating coal and petrological maturity based on hydrocarbon generation heat simulation of crude oil n-alkanes as described in claim 1, characterized in that, In step S1, when collecting samples, two immature or low-maturity core samples or outcrop samples from the same area are taken.

7. The method for calculating coal and petrological maturity based on hydrocarbon generation heat simulation of crude oil n-alkanes as described in claim 1, characterized in that, In step S1, the sample pretreatment method is as follows: crush and grind the sample, screen out powder with a particle size of 80-100 mesh and uniform particle size, and perform acid treatment on the powder to remove inorganic minerals.

Images