Minimum miscible pressure testing method based on biomarker compound index
By separating crude oil components and detecting biomarker compound indicators using GC-MS, combined with high-pressure immersion experiments, the measurement deviation and applicability problems of traditional methods under complex reservoir conditions are solved, and the accurate determination of minimum mixed pressure is achieved.
Patent Information
- Application Number
- CN202510543684.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-28
- Publication Date
- 2025-07-11
AI Technical Summary
The existing traditional minimum mixed-phase pressure measurement method has problems such as large measurement deviation, strong subjectivity and limited application scope under complex reservoir conditions. It is especially difficult to accurately measure the near-zero interface tension of the supercritical CO2-crude oil system under high temperature and high pressure conditions.
By separating crude oil into saturated hydrocarbons, aromatic hydrocarbons and gums, GC-MS was used to detect the characteristic ion peak area of each component, combined with high-pressure immersion experiments and residual oil analysis, the minimum mixed phase pressure was calculated based on the biomarker compound index, and η≥90% and k>0.6 were set as the basis for mixed phase judgment.
The accurate measurement of the minimum mixed pressure under complex reservoir conditions is achieved, and the error is reduced by more than 50%, which avoids subjective errors and insufficient applicability of traditional methods, and improves the accuracy and reliability of measurement.
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Figure CN120294204A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of oil and gas field development and enhanced oil recovery, and particularly relates to a method for measuring the minimum miscibility pressure based on biomarker compound indicators. Background Art
[0002] Currently, in oil and gas field development, gas injection flooding (such as CO2 flooding, natural gas flooding) is an important technical means to enhance oil recovery (EOR). The core lies in achieving miscibility between the injected gas and the crude oil, thereby reducing the interfacial tension and improving the oil displacement efficiency. The minimum miscibility pressure (MMP) is a key parameter to measure the effect of gas injection flooding, which is defined as the lowest pressure required for the injected gas to achieve miscibility with the crude oil.
[0003] However, existing traditional methods all have significant defects: Although the slim tube experiment method has reliable results, it requires a long-term displacement experiment of 2 - 4 weeks, and the core heterogeneity is likely to cause a measurement deviation of more than ±3 MPa; The rising bubble method relies on manual observation of the change in the bubble morphology, with a subjective interpretation error of ±15%, and it is difficult to quantitatively characterize the complex phase behavior of multi-component crude oil; The interfacial tension method suffers from coking distortion of the optical system under high temperature (>100°C) and high pressure (>30 MPa) conditions, and it is unable to accurately capture the near-zero interfacial tension (<0.1 mN / m) of the supercritical CO 2- in the crude oil system. In addition, these methods have poor adaptability to complex fluid systems such as heavy oil with a high asphaltene / resin content (>20%) or waxy oil - the slim tube experiment is likely to fail due to asphaltene deposition blocking the pores, the rising bubble method is interfered by high-viscosity crude oil resulting in inaccurate bubble dynamics, and the interfacial tension method faces the problem of polar component contamination of the optical probe. These limitations severely restrict the accuracy and engineering applicability of MMP measurement under complex reservoir conditions.
[0004] Therefore, this solution avoids the above objective problems. After CO2 is miscible with the crude oil, due to the extraction effect of CO2, the composition of the crude oil will change, and correspondingly, the biomarker compounds of the crude oil will also change. Biomarker compounds can record the historical effects on the crude oil. Currently, no method for measuring the miscibility pressure of crude oil based on crude oil biomarker compound indicators has been proposed. Therefore, developing a method for measuring the minimum miscibility pressure based on biomarker compound indicators and combining high-pressure experiments and component analysis has important theoretical significance and practical value. Summary of the Invention
[0005] The purpose of the present invention is to provide a method for measuring the minimum miscibility pressure based on biomarker compound indicators, so as to solve the problems of limitations, strong subjectivity, and limited application scope of traditional methods for measuring the minimum miscibility pressure.
[0006] To achieve the above object, the present invention provides a minimum miscibility pressure testing method based on biomarker compound indicators. The minimum miscibility pressure testing method based on biomarker compound indicator technology comprises the following steps:
[0007] Initial component analysis: Separate the crude oil into saturated hydrocarbons, aromatic hydrocarbons, and resins, and detect the characteristic ion peak areas R of n-alkanes, steranes, triaromatic steranes, and fatty acids through GC-MS 初始 ;
[0008] High-pressure soaking experiment: Place the core saturated with crude oil in a high-pressure reactor, conduct soaking experiments at different CO2 injection pressures, keep the pressure for 12 hours and then release the pressure;
[0009] Residual oil analysis: Extract the residual oil in the core after soaking, and detect the characteristic ion peak areas R of n-alkanes, steranes, triaromatic steranes, and fatty acids through GC-MS 残余 ;
[0010] Minimum miscibility pressure determination: ① Calculate the ratio of the peak areas of the residual crude oil to the initial crude oil of saturated hydrocarbons, aromatic hydrocarbons, and resins respectively according to the recovery formula. When the ratio of the peak areas of the residual crude oil to the initial crude oil of saturated hydrocarbons and aromatic hydrocarbons ≥ 90%, and the ratio of the peak areas of the residual crude oil to the initial crude oil of resins ≥ 80%; ② Construct biomarker compound indicators based on steranes, triaromatic steranes, and fatty acids, and calculate the k value according to the calculation formula of the biomarker compound indicators. When k > 0.6, determine the current pressure as the minimum miscibility pressure;
[0011] Data storage: Store the experimental data, TIC diagrams, and analysis reports;
[0012] Iterative experiment until the minimum miscibility pressure is measured: If the above experimental results do not meet the miscibility requirements, clean the high-pressure reactor with supercritical CO2, increase the pressure in steps of 1 MPa, and repeat the high-pressure soaking experiment, residual oil analysis, and minimum miscibility pressure determination until the minimum miscibility pressure is determined.
[0013] Among them, in the step of "initial component analysis", the specific testing method for the initial peak area ratio R of saturated hydrocarbons and aromatic hydrocarbons is: 初始 as follows:
[0014] Separate saturated hydrocarbons, aromatic hydrocarbons, resins, and asphaltenes by column chromatography and dry them;
[0015] Take 1.0 g of saturated hydrocarbons and aromatic hydrocarbons, add 1 ml of dichloromethane to dissolve, and then add 0.5 μg (internal standard, C 24 D 40 , m / z217) and label it as sample A;
[0016] Sample A was tested by GC-MS, and the sum of the detected ion peak areas of saturated hydrocarbons and aromatic hydrocarbons in the initial crude oil was recorded. At the same time, the ion peak area of the internal standard measured by GC-MS was recorded;
[0017] The initial peak area ratio R of saturated hydrocarbons and aromatic hydrocarbons was calculated using the initial peak area ratio calculation formula 初始 , and recorded.
[0018] Among them, in the step of "initial component analysis", the initial peak area ratio R of resins 初始 The specific test method is as follows:
[0019] Take 1.0 g of resins, add 5 ml of dichloromethane to dissolve, add 100 μg of BSTFA solvent, seal the reaction bottle, react at 80 °C for 30 minutes, and then add 0.5 μg (internal standard, C 24 D 40 , m / z 217) and label it as sample B;
[0020] Sample B was tested by GC-MS, and the sum of the detected ion peak areas of resins in the initial crude oil was recorded. At the same time, the ion peak area of the internal standard measured by GC-MS was recorded;
[0021] The initial peak area ratio R of resins was calculated using the initial peak area ratio calculation formula 初始 , and recorded.
[0022] Among them, in the step of "initial component analysis", the detected ions of n-alkanes in the saturated hydrocarbons of sample A are n-alkanes m / z 85 and steranes m / z 217.
[0023] The detected ions of monocyclic aromatic hydrocarbons in the aromatic hydrocarbons of sample A are monocyclic and polycyclic benzene rings m / z 191, and triaromatic steranes m / z 231.
[0024] The detected ions in the resins of sample B are fatty acids m / z 316, etc.
[0025] Among them, in the step of "initial component analysis", the initial peak area ratio calculation formula is:
[0026]
[0027] In the formula, A 目标碳碳氢化合物 is the detected ion peak area of saturated hydrocarbons, aromatic hydrocarbons and resins in the initial crude oil measured by GC-MS, A 内标物 is the ion peak area of the internal standard measured by GC-MS, and R 初始 is the ratio of the two.
[0028] Among them, the specific steps of the "high-pressure soaking experiment" are as follows:
[0029] The core is processed into a cube with dimensions of 15mm×15mm×5mm. The core is placed in an oven and dried for 24 hours, and the dry weight is recorded after weighing.
[0030] 100 mg of crude oil is dropped into the dried core, and it is ensured that the crude oil imbibes into the rock by observing the cross-section.
[0031] The core saturated with crude oil is placed in a high-pressure resistant reactor. The CO2 injection system and the pressure sensor are connected. After the CO2 pressure rises to the target pressure, it is soaked for 12 h. Then, the pressure relief valve is slowly opened to reduce the pressure to atmospheric pressure.
[0032] Among them, the specific steps of the "residual oil analysis" step are as follows: The soaked core is immersed in 50 mL of dichloromethane, ultrasonically treated for 30 minutes to fully dissolve the residual oil, the extract is filtered, and concentrated to 1 mL to obtain the residual liquid.
[0033] Take the residual liquid with the same mass as the initial sample A, add 0.5 μg (internal standard, C 24 D 40 , m / z 217) and record sample C.
[0034] Sample C is tested by GC-MS, and the sum of the detected ion peak areas of saturated hydrocarbons and aromatic hydrocarbons in the residual crude oil is recorded. At the same time, the ion peak area of the internal standard detected by GC-MS is recorded.
[0035] Use the initial peak area ratio calculation formula to calculate the initial peak area ratio R 初始 of saturated hydrocarbons and aromatic hydrocarbons, and record it.
[0036] Take the residual liquid with the same mass as the initial sample A, add 5 ml of dichloromethane to dissolve it, add 100 μg of BSTFA solvent, seal the reaction bottle, react at 80 °C for 30 minutes, and then add 0.5 μg (internal standard, C 24 D 40 , m / z 217) and label it as sample D.
[0037] Sample D is tested by GC-MS, and the sum of the detected ion peak areas of resins in the residual crude oil is recorded. At the same time, the ion peak area of the internal standard detected by GC-MS is recorded.
[0038] Use the residual peak area ratio calculation formula to calculate the residual peak area ratio R 残余 of saturated hydrocarbons, aromatic hydrocarbons and resins, and record it.
[0039] Among them, in the "residual oil analysis" step, the residual peak area ratio calculation formula is:
[0040]
[0041] In the formula, A 残余目标碳碳氢化合物is the detected ion peak area of saturated hydrocarbons, aromatic hydrocarbons, and resins in the residual crude oil measured by GC-MS, A 内标物 is the peak area of the internal standard measured by GC-MS, R 残余 is the ratio of the two.
[0042] Among them, in the step of "minimum miscibility pressure determination", the oil recovery calculation formula is:
[0043]
[0044] In the formula, η is the ratio of the peak area of the residual crude oil to the initial crude oil.
[0045] In the step of "minimum miscibility pressure determination", the calculation formula for the biomarker compound index for minimum miscibility pressure determination is:
[0046]
[0047] In the formula, k is the biomarker compound index.
[0048] In a method for testing the minimum miscibility pressure based on biomarker compound indices of the present invention, first, the crude oil is separated into saturated hydrocarbons, aromatic hydrocarbons, and resins, the characteristic ion peak areas of each component are detected by GC-MS, and the initial peak area ratio R 初始 of each component is calculated respectively. Then, through high-pressure soaking experiments and residual oil analysis, the residual peak area ratio R 残余 of each component is obtained. Finally, according to the oil recovery calculation formula, the ratios of the peak areas of the residual crude oil to the initial crude oil of saturated hydrocarbons, aromatic hydrocarbons, and resins are calculated respectively. When the ratios of the peak areas of the residual crude oil to the initial crude oil of saturated hydrocarbons and aromatic hydrocarbons are ≥ 90%, and the ratio of the peak area of the residual crude oil to the initial crude oil of resins is ≥ 80%, and the calculated result k of the biomarker compound index > 0.6, then the current pressure can be determined as the minimum miscibility pressure. This technical solution directly quantifies the oil recovery through the dynamic change of the peak area ratio before and after the crude oil drawer experiment, avoids the subjective error of macroscopic experiments (such as the slim tube method), and at the same time, the internal standard method calibration ensures data comparability, and the error is reduced by more than 50% compared with the traditional method; setting η ≥ 90% and k > 0.6 as the threshold for the miscibility judgment basis can be flexibly set. Brief Description of the Drawings
[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.
[0050] Figure 1It is the flow chart of the minimum miscibility pressure test method based on GC-MS technology provided by the present invention.
[0051] Figure 2 It is the total ion current chromatogram of tic before reaction provided by the present invention.
[0052] Figure 3 It is the total ion current chromatogram of tic after reaction provided by the present invention.
[0053] Figure 4 It is the ion chromatogram with a mass-to-charge ratio of 85 in the residual liquid after reaction provided by the present invention.
[0054] Figure 5 It is the ion chromatogram with a mass-to-charge ratio of 217 in the residual liquid after reaction provided by the present invention.
[0055] Figure 6 It is the ion chromatogram with a mass-to-charge ratio of 231 in the residual liquid after reaction provided by the present invention. Detailed implementation manners
[0056] The embodiments of the present invention are described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.
[0057] Please refer to Figures 1 to 6 , the present invention provides a minimum miscibility pressure test method based on biomarker compound indicators. The minimum miscibility pressure test method based on GC-MS technology includes the following steps:
[0058] S1. Initial component analysis: Separate crude oil into saturated hydrocarbons, aromatic hydrocarbons and resins, and detect the characteristic ion peak areas R of n-alkanes, steranes, triaromatic steranes and fatty acids through GC-MS 初始 ;
[0059] S2. High-pressure soaking experiment: Place the core of saturated crude oil in a high-pressure reactor, conduct soaking experiments at different injection CO2 pressures, keep the pressure for 12 hours and then relieve the pressure;
[0060] S3. Residual oil analysis: Extract the residual oil in the core after soaking, and detect the characteristic ion peak areas R of n-alkanes, steranes, triaromatic steranes and fatty acids through GC-MS 残余 ;
[0061] S4. Minimum miscibility pressure determination: ① Calculate the peak area ratios of the residual crude oil to the initial crude oil for saturated hydrocarbons, aromatic hydrocarbons, and resins respectively according to the recovery formula. When the peak area ratios of the residual crude oil to the initial crude oil for saturated hydrocarbons and aromatic hydrocarbons are ≥ 90%, and the peak area ratio of the residual crude oil to the initial crude oil for resins is ≥ 80%; ② Construct biomarker indices based on steranes, triaromatic steranes, and fatty acids, and calculate the k value according to the calculation formula of the biomarker indices. When k > 0.6, determine the current pressure as the minimum miscibility pressure;
[0062] S5. Data preservation: Preserve the experimental data, TIC diagrams, and analysis reports;
[0063] S6. Iterative experiments until the minimum miscibility pressure is measured: If the experiment does not meet the miscibility standard, rinse the high-pressure reactor with supercritical CO2, increase the pressure in steps of 1 MPa, and repeat the high-pressure soaking experiment, residual oil analysis, and minimum miscibility pressure determination until the minimum miscibility pressure is determined.
[0064] In this embodiment, first, the crude oil is separated into saturated hydrocarbons, aromatic hydrocarbons, and resins, the characteristic ion peak areas of each component are detected by GC-MS, and the initial peak area ratios R of each component are calculated respectively. 初始 Then, through the high-pressure soaking experiment and residual oil analysis, the residual peak area ratios R of each component are obtained. 残余 Finally, calculate the peak area ratios of the residual crude oil to the initial crude oil for saturated hydrocarbons, aromatic hydrocarbons, and resins respectively according to the recovery formula. When the peak area ratios of the residual crude oil to the initial crude oil for saturated hydrocarbons and aromatic hydrocarbons are ≥ 90%, and the peak area ratio of the residual crude oil to the initial crude oil for resins is ≥ 80%, and the calculated result k of the biomarker indices > 0.6, then the current pressure can be determined as the minimum miscibility pressure.
[0065] This technical solution directly quantifies the recovery rate through the dynamic change of the peak area ratio before and after the crude oil drawer experiment, avoids the subjective error of macroscopic experiments (such as the slim tube method), and at the same time, the internal standard method calibration ensures the comparability of data, and the error is reduced by more than 50% compared with the traditional method; setting η ≥ 90% and k > 0.6 as the threshold for the miscibility judgment basis can be flexibly set.
[0066] Further, in the step of "initial component analysis", the specific test method for the initial peak area ratio R of saturated hydrocarbons and aromatic hydrocarbons is as follows: 初始 Separate saturated hydrocarbons, aromatic hydrocarbons, resins, and asphaltenes by column chromatography and dry them;
[0067] Take 1.0 g of saturated hydrocarbons and aromatic hydrocarbons, add 1 ml of dichloromethane to dissolve, and then add 0.5 μg (internal standard, C
[0068] D 24 D 40 , m / z217) and label it as sample A;
[0069] Test sample A by GC-MS, record the sum of the detected ion peak areas of saturated hydrocarbons and aromatic hydrocarbons in the initial crude oil, and at the same time record the ion peak area of the internal standard measured by GC-MS;
[0070] Use the initial peak area ratio calculation formula to calculate the initial peak area ratio R of saturated hydrocarbons and aromatic hydrocarbons 初始 , and record it.
[0071] Furthermore, in the step of "initial component analysis", the specific test method for the initial peak area ratio R 初始 of gum is as follows:
[0072] Take 1.0 g of gum, add 5 ml of dichloromethane to dissolve it, add 100 μg of BSTFA solvent, seal the reaction bottle, react at 80 °C for 30 minutes, and then add 0.5 μg (internal standard, C 24 D 40 , m / z 217) and label it as sample B;
[0073] Test sample B by GC-MS, record the sum of the detected ion peak areas of gum in the initial crude oil, and at the same time record the ion peak area of the internal standard measured by GC-MS;
[0074] Use the initial peak area ratio calculation formula to calculate the initial peak area ratio R 初始 of gum, and record it.
[0075] Among them, in the step of "initial component analysis", the detected ions of n-alkanes in saturated hydrocarbons of sample A are n-alkanes m / z 85 and steranes m / z 217;
[0076] The detected ions of monocyclic aromatic hydrocarbons in aromatic hydrocarbons of sample A are monocyclic and polycyclic benzene rings m / z 191, etc., and triaromatic steroids m / z 231;
[0077] The detected ions in gum of sample B are fatty acids m / z 316, etc.
[0078] Among them, in the step of "initial component analysis", the initial peak area ratio calculation formula is:
[0079]
[0080] In the formula, A 目标碳碳氢化合物 is the detected ion peak area of saturated hydrocarbons, aromatic hydrocarbons and gum in the initial crude oil measured by GC-MS, A 内标物 is the ion peak area of the internal standard measured by GC-MS, and R 初始 is the ratio of the two.
[0081] Among them, the specific steps of the step of "high-pressure soaking experiment" are as follows:
[0082] The core is processed into a cube with dimensions of 15 mm × 15 mm × 5 mm. The core is placed in an oven and dried for 24 hours, and the dry weight is recorded after weighing.
[0083] 100 mg of crude oil is dropped into the dried core, and it is ensured that the crude oil imbibes into the rock by observing the cross-section.
[0084] The core saturated with crude oil is placed in a high-pressure resistant reactor. The CO2 injection system and pressure sensor are connected. After the CO2 pressure rises to the target pressure, it is soaked for 12 h. Then, the pressure relief valve is slowly opened to reduce the pressure to atmospheric pressure.
[0085] Among them, the specific steps of the "residual oil analysis" step are as follows: The soaked core is immersed in 50 mL of dichloromethane, ultrasonically treated for 30 minutes to fully dissolve the residual oil, the extract is filtered, and concentrated to 1 mL to obtain a residual liquid.
[0086] Take a residual liquid with the same mass as the initial sample A, add 0.5 μg (internal standard, C 24 D 40 , m / z 217) and record sample C.
[0087] Sample C is tested by GC-MS, and the sum of the detected ion peak areas of saturated hydrocarbons and aromatic hydrocarbons in the residual crude oil is recorded. At the same time, the ion peak area of the internal standard detected by GC-MS is recorded.
[0088] Use the initial peak area ratio calculation formula to calculate the initial peak area ratio R 初始 of saturated hydrocarbons and aromatic hydrocarbons, and record it.
[0089] Take a residual liquid with the same mass as the initial sample A, add 5 ml of dichloromethane to dissolve it, add 100 μg of BSTFA solvent, seal the reaction bottle, react at 80 °C for 30 minutes, and then add 0.5 μg (internal standard, C 24 D 40 , m / z 217) and label it as sample D.
[0090] Sample D is tested by GC-MS, and the sum of the detected ion peak areas of resins in the residual crude oil is recorded. At the same time, the ion peak area of the internal standard detected by GC-MS is recorded.
[0091] Use the residual peak area ratio calculation formula to calculate the residual peak area ratio R 残余 of saturated hydrocarbons, aromatic hydrocarbons and resins, and record it.
[0092]
[0093] In the formula, A 残余目标碳碳氢化合物 is the detected ion peak area of saturated hydrocarbons, aromatic hydrocarbons and resins in the residual crude oil measured by GC-MS, A内标物 is the peak area of the internal standard measured by GC-MS, R 残余 is the ratio of the two.
[0094] Among them, in the step of "minimum miscibility pressure determination", the oil recovery calculation formula is:
[0095]
[0096] In the formula, η is the ratio of the peak area of residual crude oil to that of initial crude oil.
[0097] In the step of "minimum miscibility pressure determination", the calculation formula for the biomarker index for minimum miscibility pressure determination is:
[0098]
[0099] Further, when testing samples A, B, C, and D by GC-MS, the column used in the GC-MS instrument settings is a DB-5MS column (inner diameter 60 m × 0.25 mm × film thickness 0.25 μm). The oven temperature program is as follows: hold at 40 °C for 4 minutes, then increase from 40 °C to 120 °C at a rate of 15 °C / min, then increase from 120 °C to 290 °C at a rate of 4 °C / min, and finally hold at 290 °C for 27.5 minutes. The temperatures of the injector and transfer line are both maintained at 300 °C. Helium is used as the carrier gas with a flow rate of 1.3 mL / min. The ion source temperature of the MS is maintained at 300 °C, and the electron beam ionization energy is set at 70 eV.
[0100] Further, in the step of "high-pressure soaking experiment", the set initial pressure is 50% of the expected minimum miscibility pressure.
[0101] Further, in the step of "data saving", the experimental data, TIC diagrams, and analysis reports saved are shown in Table 1:
[0102] Table 1
[0103]
[0104] When the oil recovery rates of saturated hydrocarbons and aromatic hydrocarbons ≥ 90% and resins ≥ 80%, and the result k > 0.6 is calculated for the biomarker index according to the calculation formula for the biomarker index, then the current pressure is the minimum miscibility pressure.
[0105] Further, the high-pressure reactor is connected to the pressurizing equipment and the CO2 injection system, and the pressure is adjusted through a pressure regulating valve.
[0106] Further, the 0.5 μg (internal standard, C 24 D 40, for m / z 217), a deuterated compound with stable chemical properties and no cross-reaction with crude oil components (such as C 24 D 40 cholane) should be used to ensure the reliability of quantitative calibration; the addition amount of the internal standard should be precisely controlled (0.5 μg ± 0.1 μg) to avoid affecting the peak area ratio due to excess or deficiency.
[0107] Furthermore, the GC-MS parameter calibration chromatographic column needs to be regularly aged (maintained at 290 °C for 30 minutes) to prevent column efficiency decay; the mass spectrometry ion source temperature (300 °C) and electron energy (70 eV) must strictly match the ionization efficiency of the target component.
[0108] The above-disclosed is only a preferred embodiment of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Those of ordinary skill in the art can understand all or part of the processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the invention.
Claims
1. A minimum miscibility pressure test method based on biomarker compound indicators, characterized in that, It includes the following steps: Initial component analysis: The crude oil is separated into saturated hydrocarbons, aromatic hydrocarbons and resins, and the characteristic ion peak areas R of n-alkanes, steranes, triaromatic steranes and fatty acids are detected by GC-MS 初始 ; High-pressure soaking experiment: Place the core saturated with crude oil in a high-pressure reactor, conduct soaking experiments at different CO2 injection pressures, keep the pressure for 12 hours and then relieve the pressure; Residual oil analysis: The residual oil in the core after extraction and soaking is detected by GC-MS for the characteristic ion peak areas R of n-alkanes, steranes, triaromatic steranes, and fatty acids 残余 ; Minimum miscibility pressure determination: ① Calculate the peak area ratio of the residual crude oil to the initial crude oil of saturated hydrocarbons, aromatic hydrocarbons and resins respectively according to the recovery rate calculation formula. When the peak area ratio of the residual crude oil to the initial crude oil of saturated hydrocarbons and aromatic hydrocarbons ≥ 90%, and the peak area ratio of the residual crude oil to the initial crude oil of resins ≥ 80%; ② Construct biomarker compound indexes based on steranes, triaromatic steranes and fatty acids, and calculate the k value according to the calculation formula of biomarker compound indexes. When k > 0.6, determine the current pressure as the minimum miscibility pressure; Data storage: Store experimental data, TIC diagrams and analysis reports; Iterative experiments until the minimum miscibility pressure is measured: If the above experimental results do not meet the miscibility requirements, clean the high-pressure reactor with supercritical CO2, increase the pressure in steps of 1 MPa, and repeat the high-pressure soaking experiment, residual oil analysis and minimum miscibility pressure determination until the minimum miscibility pressure is determined.
2. The minimum miscibility pressure testing method based on GC-MS technology according to claim 1, characterized in that In the step of "initial component analysis", the initial peak area ratio R of saturated hydrocarbons and aromatic hydrocarbons 初始 is measured by the following specific method: Separate saturated hydrocarbons, aromatic hydrocarbons, resins and asphaltenes by column chromatography and dry them; Take 1.0 g of saturated hydrocarbons and aromatic hydrocarbons, add 1 ml of dichloromethane to dissolve, and then add 0.5 μg (internal standard, C 24 D 40 , m / z 217) and label it as sample A; Test sample A by GC-MS, record the sum of the detected ion peak areas of saturated hydrocarbons and aromatic hydrocarbons in the initial crude oil, and record the ion peak area of the internal standard measured by GC-MS at the same time; Calculate the initial peak area ratio R of saturated hydrocarbons and aromatic hydrocarbons using the initial peak area ratio calculation formula and record it. 初始 , and record it.
3. The minimum miscibility pressure testing method based on GC-MS technology according to claim 2, characterized in that In the step of "initial component analysis", the initial peak area ratio R of the gum 初始 The specific test method is as follows: Take 1.0 g of colloid, add 5 ml of dichloromethane to dissolve it, add 100 μg of BSTFA solvent, seal the reaction flask, react at 80 °C for 30 minutes, and then add 0.5 μg (internal standard, C 24 D 40 , m / z 217) and label it as sample B; Test sample B by GC-MS, record the sum of the detected ion peak areas of resins in the initial crude oil, and record the ion peak area of the internal standard measured by GC-MS at the same time; Calculate the initial peak area ratio R of the gum using the initial peak area ratio calculation formula and record it. 初始 , and record it.
4. The minimum miscibility pressure testing method based on GC-MS technology according to claim 3, characterized in that Among them, in the step of "initial component analysis", the detected ions of n-alkanes in the saturated hydrocarbons of sample A are n-alkane m / z 85 and steranes m / z 217 The detected ions of monocyclic aromatic hydrocarbons in the aromatic hydrocarbons of sample A are monocyclic and polycyclic benzene rings m / z 191, and triaromatic steroids m / z 231; The detected ions in the resins of sample B are fatty acids m / z 316.
5. The minimum miscibility pressure testing method based on GC-MS technology according to claim 4, characterized in that In the step of "initial component analysis", the calculation formula of the initial peak area ratio is: In the formula, A 目标碳碳氢化合物 is the detection ion peak area of saturated hydrocarbons, aromatic hydrocarbons and resins in the initial crude oil measured by GC-MS, and A 内标物 is the ion peak area of the internal standard measured by GC-MS. R 初始 is the ratio of the two.
6. The minimum miscibility pressure testing method based on GC-MS technology according to claim 5, characterized in that Among them, The specific steps of the step of "high-pressure soaking experiment" are: Process the core into a cube of 15mm×15mm×5mm, place the core in an oven and dry it for 24 hours, weigh and record the dry weight; Drop 100 mg of crude oil into the dried core, and ensure that the crude oil imbibes into the rock through cross-sectional observation; Put the core saturated with crude oil into a high-pressure resistant reactor, connect the CO2 injection system and the pressure sensor, soak for 12 h after the CO2 pressure rises to the target pressure; start to slowly open the pressure relief valve to reduce the pressure to atmospheric pressure.
7. The minimum miscibility pressure testing method based on GC-MS technology according to claim 6, It is characterized in that Among them, the specific steps of the step "residual oil analysis" are as follows: Immerse the soaked core in 50 mL of dichloromethane, ultrasonically treat for 30 minutes to fully dissolve the residual oil, filter the extract, and concentrate it to 1 mL to obtain the residual liquid; Take the residual liquid with the same mass as the initial sample A, add 0.5 μg (internal standard, C 24 D 40 , m / z 217) and record sample C; Test sample C by GC-MS, record the sum of the detected ion peak areas of saturated hydrocarbons and aromatic hydrocarbons in the residual crude oil, and at the same time record the ion peak area of the internal standard measured by GC-MS; Calculate the initial peak area ratio R of saturated hydrocarbons and aromatic hydrocarbons using the initial peak area ratio calculation formula, and record it; 初始 Take the residual liquid with the same mass as the initial sample A, add 5 ml of dichloromethane to dissolve it, add 100 μg of BSTFA solvent, seal the reaction flask, react at 80 °C for 30 minutes, and then add 0.5 μg (internal standard, C 24 D 40 , m / z 217) and label it as sample D; Test sample D by GC-MS, record the sum of the detected ion peak areas of resins in the residual crude oil, and at the same time record the ion peak area of the internal standard measured by GC-MS; Calculate the residual peak area ratios R of saturated hydrocarbons, aromatic hydrocarbons, and resins using the residual peak area ratio calculation formula, and record them. 残余 , and record.
8. The minimum miscibility pressure testing method based on GC-MS technology according to claim 7, characterized in that In the step "residual oil analysis", the calculation formula for the residual peak area ratio is: Where, A 残余目标碳碳氢化合物 is the detected ion peak areas of saturated hydrocarbons, aromatic hydrocarbons and resins in the residual crude oil measured by GC-MS, A 内标物 is the peak area of the internal standard measured by GC-MS, and R 残余 is the ratio of the two.
9. The minimum miscibility pressure testing method based on GC-MS technology according to claim 8, characterized in that In the step "minimum miscibility pressure determination", the calculation formula for the recovery factor is: In the formula, η is the ratio of the peak area of the residual crude oil to the initial crude oil. The calculation formula for the biomarker compound index is: In the formula, k is the biomarker compound index.