A comprehensive testing method and system for reservoir properties under dissolution during carbon dioxide flooding in tight oil reservoirs

Abstract

This invention discloses a comprehensive testing method and system for reservoir properties under dissolution during carbon dioxide flooding in tight oil reservoirs. The method focuses on testing and comparing the dry weight, pore throat structure, pore size distribution, and permeability of core samples before and after carbon dioxide flooding to comprehensively characterize the impact of dissolution on reservoir properties. This method has the advantages of combining dynamic and static analysis, macroscopic and microscopic analysis, and results with process analysis. It is significant for establishing the correlation between dissolution reaction intensity and mineral composition, pressure changes, degree of property improvement, and pore throat distribution. The new method provides a more systematic and scientific analysis of the dissolution process and its impact on reservoir properties, filling a technological gap.

Description

Technical Field

[0001] This invention relates to the field of enhanced oil recovery technology in oil and gas field development, specifically to a comprehensive testing method and system for reservoir properties under the dissolution effect of carbon dioxide flooding in tight oil reservoirs. Background Technology

[0002] Carbon dioxide capture, utilization, and storage (CCUS) technology, as an artificial carbon reduction measure, has become a focus of attention in the energy industry. Among them, CCUS-EOR is an enhanced oil recovery technology that uses carbon dioxide for oil displacement, and its development is of great significance. Especially for tight sandstone reservoirs, under the reservoir's temperature and pressure conditions, injected carbon dioxide reacts with formation water to form a weak acid, which then reacts chemically with calcite, dolomite, feldspar, and other minerals in the rock. Simultaneously, secondary minerals generated by the reaction migrate, thus microscopically altering the reservoir's pore-throat structure and distribution characteristics, macroscopically manifesting as changes in reservoir properties. This process is largely negligible for conventional medium-to-high permeability reservoirs (due to their large pore-throat scale and limited improvement in properties from dissolution). However, for tight sandstone reservoirs with micro- and nano-scale pores, this process is significant, introducing considerable uncertainty to effective carbon dioxide injection, efficient oil displacement, and safe storage. Therefore, systematic testing and analysis of the dissolution process during carbon dioxide flooding is crucial.

[0003] Currently, the testing and analysis of carbon dioxide flooding and dissolution mainly utilizes physical simulation methods, focusing on testing and comparing reservoir permeability and porosity before and after carbon dioxide flooding to characterize the degree of influence of dissolution on reservoir properties. Existing methods have two main drawbacks: first, they do not systematically analyze the material basis and reaction conditions for dissolution; second, they do not reflect how the microscopic pore throat structure changes after dissolution and its impact on properties. Summary of the Invention

[0004] To address the problem that current methods for testing and analyzing the dissolution effects of carbon dioxide flooding (CFD) are limited (primarily focusing on macroscopic property changes), leading to a lack of understanding of the mechanisms by which dissolution affects reservoir properties, this paper proposes a comprehensive method and system for testing and analyzing CFD-induced dissolution. This system integrates rock and mineral composition determination, formation water pH testing under reservoir conditions, static electron microscopy, and dynamic nuclear magnetic resonance simulation, based on the chemical reaction conditions of dissolution.

[0005] This invention first provides a comprehensive testing method for reservoir properties under the dissolution effect of carbon dioxide flooding in tight oil reservoirs, including the following steps:

[0006] 1) Select core wells within the target tight oil reservoir area to obtain natural cores; based on the chemical formula of the reaction between carbon dioxide and rock minerals, determine the characteristic mineral component types of the dissolution reaction in the target tight oil reservoir and test the content of dissolution mineral components in the natural cores to complete the test of the material basis of the dissolution reaction in the carbon dioxide flooding process.

[0007] 2) At the target tight reservoir temperature, test the pH value of formation water with carbon dioxide introduced at different pressures to complete the reaction condition test of the dissolution reaction during the carbon dioxide flooding process.

[0008] 3) The dry weight of natural cores before and after carbon dioxide flooding under different pressures was tested by weighing method; and the surface images of the samples before and after carbon dioxide flooding under different pressures were scanned by scanning electron microscopy; the dry weight of the samples and the surface images of the samples before and after carbon dioxide flooding under different pressures were compared to calculate the rate of change of core dry weight and core porosity.

[0009] 4) Test the porosity and permeability of natural cores before and after carbon dioxide flooding under different pressures. At the same time, conduct nuclear magnetic resonance tests on the cores before and after gas injection under different pressures to obtain T2 spectra under different pressures, and calculate the pore throat radius based on the T2 spectra.

[0010] 5) The influence of dissolution on reservoir properties is characterized by changes in core dry weight, core surface porosity, core permeability, and pore throat radius distribution.

[0011] This invention also provides a system for a comprehensive testing method of reservoir properties under the dissolution effect of carbon dioxide flooding in tight oil reservoirs, comprising:

[0012] The core dissolution mineral component analysis module is used to obtain the natural core of the target oil reservoir. Based on the chemical formula of the reaction between carbon dioxide and rock minerals, it determines the characteristic mineral component types of the dissolution reaction of the target oil reservoir and tests the content of dissolution mineral components in the core of the target oil reservoir.

[0013] The formation water pH testing module is used to test the pH value of saturated formation water with dissolved carbon dioxide at different pressures under target reservoir temperatures.

[0014] The core dry weight change rate calculation module is used to test and compare the dry weight of samples before carbon dioxide flooding under different pressures using the weighing method, thereby calculating the core dry weight change rate.

[0015] The core pore throat variation calculation module is used to scan and compare images of the sample surface before and after carbon dioxide flooding under different pressures using a scanning electron microscope, thereby calculating the core porosity.

[0016] The core porosity and permeability detection module is used to detect the porosity and permeability of samples before and after carbon dioxide flooding under different pressures;

[0017] The nuclear magnetic resonance module is used to conduct nuclear magnetic resonance tests on cores before and after gas injection under different pressures, obtain T2 spectra under different pressures, and calculate the pore throat radius based on the T2 spectra.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1) This invention patent takes into account the material basis (characteristic mineral components) and reaction conditions (pH) of the dissolution reaction in the carbon dioxide flooding process, overcomes the problem of unclear conditions for the dissolution reaction in existing methods, and is an effective supplement to existing methods, which is more scientific and reasonable;

[0020] 2) This invention patent employs electron microscopy to observe changes in pore throat structure (direct qualitative observation) and nuclear magnetic resonance to compare changes in pore size distribution (indirect quantitative characterization) as support for conventional near-field testing of rock cores to detect permeability or porosity changes. This overcomes the problem of existing methods failing to clearly explain the underlying causes of core property changes due to dissolution, and provides a more in-depth analysis of the intrinsic mechanisms of dissolution reactions.

[0021] 3) This invention patent adopts a comprehensive evaluation technology using different testing methods. By assigning different weights to different experimental results, it quantitatively characterizes the degree of dissolution reaction, overcoming the problem that existing methods do not classify and grade the degree of dissolution. The evaluation considers more comprehensive factors and the results are more scientific. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the effect of pressure at reservoir temperature on the pH value of dissolved CO2 water.

[0023] Figure 2 This is a schematic diagram comparing the T2 NMR values ​​of samples before and after carbon dioxide flooding at a certain injection pressure.

[0024] Figure 3 This is a comprehensive diagram showing the degree of static dissolution under different reaction pressures;

[0025] Figure 4 A comprehensive diagram showing the dynamic degree of dissolution under different reaction pressures;

[0026] Figure 5 Diagram showing changes in core pore size before and after carbon dioxide flooding;

[0027] Figure 6 This is a graph showing the amplitude difference of relaxation time signals of core samples with different pore sizes before and after carbon dioxide flooding under a certain pressure.

[0028] Figure 7 This is a flowchart of the experimental evaluation process for this invention. Detailed Implementation

[0029] The present invention will be further described and illustrated below with reference to specific embodiments. The embodiments described are merely examples of the content of this disclosure and do not limit the scope of the invention. The technical features of each embodiment in the present invention can be combined accordingly, provided that there is no mutual conflict.

[0030] This invention proposes a testing and analysis method based on the reaction process of carbon dioxide with rocks and minerals and the pH change of formation water driven by dissolved carbon dioxide. It integrates physical simulation to test the changes in core pore permeability, electron microscopy to qualitatively observe dissolution channels, and nuclear magnetic resonance analysis to analyze the distribution changes of different pore throats. This method can more scientifically and deeply analyze the intensity and degree of dissolution in the carbon dioxide flooding process of tight sandstone reservoirs, which is of great significance for evaluating the feasibility of CCUS projects.

[0031] This invention describes a method and system for testing and analyzing the dissolution effect during carbon dioxide flooding in oil reservoirs. The method of this invention is as follows: Figure 7 As shown, the process includes five steps: First, based on the chemical formula of the reaction between carbon dioxide and rock minerals, the characteristic mineral component types of the dissolution reaction are identified; natural cores of the target reservoir are obtained, and the content of dissolution mineral components is tested; second, the pH value of deionized water containing dissolved carbon dioxide is tested at different pressures under different reservoir temperatures; third, static dissolution testing is conducted, using weighing and scanning electron microscopy to test the dry weight and surface images of samples before and after carbon dioxide flooding and at different pressures; fourth, dynamic dissolution testing is conducted, using physical simulation to test the porosity and permeability of the reservoir before and after carbon dioxide flooding at different pressures, and nuclear magnetic resonance testing is carried out before and after core gas injection and at different pressures to obtain T2 spectra at different pressures; fifth, the degree of influence of dissolution on reservoir properties is analyzed, and the pore throat distribution characteristics are compared.

[0032] Furthermore, it can determine the degree of carbon dioxide flooding dissolution in the target reservoir based on the established criteria for judging the degree of dissolution.

[0033] The specific process of this invention is as follows:

[0034] 1) Based on the chemical formula of the reaction between carbon dioxide and rock minerals, identify the characteristic mineral component types of the dissolution reaction; obtain natural core samples from the target reservoir and test the content of its dissolution mineral components.

[0035] The dissolution process of calcite and dolomite: CO2 + H2O + C a CO3→C a 2+ +2HCO3 -

[0036] Dissolution process of Changbai Stone: C a Al₂Si₂O₈ + H₂CO₃ + H₂O → C a CO3+Al2Si2O5(OH)4.

[0037] Among the rock minerals, calcite, dolomite, and feldspar are involved in the CO2 dissolution reaction and form the material basis for this reaction. On one hand, the acidic fluid formed by CO2 dissolving in formation water dissolves the cement in the rock, thereby increasing the reservoir's permeability. On the other hand, the formation water contains scale-forming ions (CaO) after the dissolution reaction. 2+ The continuous increase in calcium carbonate content and inorganic precipitation, along with changes in reservoir pressure, temperature, and other conditions, leads to the formation and migration of secondary minerals, which can clog pores and reduce reservoir permeability. Therefore, the impact of dissolution reactions on reservoir properties is the result of the combined effects of both factors.

[0038] a. Select core wells within the current reservoir area, and on the basis of ensuring similar lithology and mineral composition, carry out natural core drilling, cutting and oil washing in accordance with SY / T5336 "Rock Analysis Methods" to complete the core preparation work;

[0039] b. Based on the obtained core samples, test the mineral content of the target reservoir rocks, focusing on evaluating the content of three dissolution reaction minerals: calcite, dolomite, and feldspar. In a specific embodiment of this invention, the tests are performed according to the standard SY / T5163-2018 "X-ray Diffraction Analysis Methods for Clay Minerals and Common Non-Clay Minerals in Sedimentary Rocks".

[0040] 2) At the target reservoir temperature, test the pH value of formation water saturated with carbon dioxide under different pressures.

[0041] Rinse the calibrated pressure-resistant electrode with deionized water, blot dry with filter paper, and load the solution to be tested into the high-pressure pH testing device, inserting the pH electrode. After preheating the solution to the specified temperature, introduce carbon dioxide gas to the specified pressure. Gradually increase the pressure and record the equilibrium reading displayed on the pH meter at each pressure point, such as... Figure 1 As shown.

[0042] 3) Static dissolution test: The dry weight and surface images of the samples before and after carbon dioxide displacement and under different pressures were measured using a gravimetric method and scanning electron microscopy, such as... Figure 3 As shown.

[0043] a. After pretreatment of the sample according to the requirements of scanning electron microscopy testing, obtain the scanning electron microscope image and dry weight before carbon dioxide displacement;

[0044] b. Place the sample in a high-temperature, high-pressure, visual autoclave containing deionized water, preheat the solution to the reservoir temperature, then introduce carbon dioxide gas to the specified pressure. After the dissolution reaction is fully completed, remove the sample and obtain a core scanning electron microscope image and dry weight under that pressure. In a specific embodiment of the present invention, the dissolution reaction time is 24 hours.

[0045] c. Scanning electron microscope images and dry weights of samples after reacting with carbon dioxide at different pressures, as per b;

[0046] d. Compare the scanning electron microscopy and dry weight of samples under different pressures to observe the changes in the pore throat of the core.

[0047] 4) Dynamic dissolution reaction test. Based on the selected target reservoir natural core, the permeability of the samples before and after carbon dioxide flooding under different pressures was tested using physical simulation. Nuclear magnetic resonance tests were carried out simultaneously before and after gas injection and under different pressures to obtain T2 spectra under different pressures.

[0048] a. Testing the permeability of natural core samples before carbon dioxide flooding; in one specific embodiment of the present invention, the test is performed in accordance with the standard SY / T 5354-2007 "Determination of Relative Permeability of Two-Phase Fluids in Rocks".

[0049] b. In accordance with the requirements of nuclear magnetic resonance, after the core is saturated with deionized water, a nuclear magnetic resonance test is performed to obtain the T2 map before the reaction;

[0050] C. Begin the carbon dioxide flooding experiment. Inject carbon dioxide at a specified pressure and obtain the NMR T2 map after carbon dioxide flooding at that pressure;

[0051] d. Following C, change the injection pressure to obtain T2 diagrams after carbon dioxide displacement at different pressures; in a specific embodiment of the present invention, the obtained T2 diagram is as follows: Figure 2 As shown.

[0052] 5) Data processing and analysis of static and dynamic dissolution reactions

[0053] a. Characterization of the degree of static dissolution reaction

[0054] The degree of static dissolution reaction is quantitatively characterized by the rate of change of sample mass ω before and after the carbon dioxide reaction. The calculation formula is as follows:

[0055]

[0056] ω i The rate of mass change of a sample after it undergoes a dissolution reaction with carbon dioxide at a certain reaction pressure; m o : The mass of the sample before it undergoes the dissolution reaction with carbon dioxide; m i The mass of a sample after it undergoes a dissolution reaction with carbon dioxide under a certain reaction pressure;

[0057] Simultaneously, by combining electron micrographs of samples under different pressures, a comprehensive diagram of the degree of static dissolution reaction caused by carbon dioxide flooding was drawn, and the porosity and its rate of change on the core surface were calculated.

[0058]

[0059] χ iS: The rate of change in porosity of a sample after it undergoes a dissolution reaction with carbon dioxide under a certain reaction pressure; o : Porosity of the sample before it undergoes a dissolution reaction with carbon dioxide; S i The porosity of a sample after it undergoes a dissolution reaction with carbon dioxide under a certain reaction pressure.

[0060] b. Characterization of the degree of dynamic dissolution reaction

[0061] The degree of dynamic dissolution reaction is quantitatively characterized by the change in sample permeability before and after carbon dioxide flooding. The calculation formula is as follows:

[0062]

[0063] λ i K: The rate of change in gas permeability after a sample undergoes a dissolution reaction with carbon dioxide at a certain reaction pressure; o : Gas permeability of the sample before it undergoes a dissolution reaction with carbon dioxide; K i : Gas permeability measured after a sample undergoes a dissolution reaction with carbon dioxide at a certain injection pressure;

[0064] A graph depicting the degree of carbon dioxide-driven dissolution reaction under different pressures was plotted. In a specific embodiment of the present invention, the plotted graph is as follows: Figure 4 As shown.

[0065] c. Dynamic dissolution degree characterization based on nuclear magnetic resonance

[0066] The principle of nuclear magnetic resonance (NMR) indicates that relaxation time is directly proportional to pore radius. According to GB-T 42035-2022 "Determination of Pore Size Distribution in Coal and Rock - Nuclear Magnetic Resonance Method", relaxation time is converted into pore radius, i.e.

[0067]

[0068] In the formula: r is the pore radius; T2 is the NMR relaxation time; C is the conversion coefficient; and n is the exponent. C and n can be obtained by fitting the formula to the cumulative distribution curves of pore size and T2 relaxation time from mercury porosimetry data and the NMR data.

[0069] Based on the T2 diagrams of the samples before and after carbon dioxide flooding and the conversion relationship between pore size and T2, the following results were obtained: Figure 5 The changes in pore size of the core sample before and after carbon dioxide flooding are shown in the following formula:

[0070] ΔE i (r)=E i (r)-E o (r)

[0071] ΔE i(r) represents the difference in relaxation signal amplitude of the core sample with pore size r before and after gas injection. A value greater than 0 indicates an increase in the number of pores with pore size r, and vice versa. E o (r) represents the amplitude of the relaxation signal of the core sample with pore size r before gas injection, E i (r) represents the amplitude of the relaxation signal of the core sample with a pore size of r.

[0072] Drawing as Figure 6 The curves showing the difference in relaxation signal amplitude before and after carbon dioxide flooding in core samples with different pore sizes are shown.

[0073] The degree of variation for different aperture sizes is calculated using the following formula.

[0074]

[0075] Where, ε i (r) represents the change in the proportion of channels with aperture r; ∑E o (r) represents the cumulative value of the relaxation signal amplitude for different apertures before air drive;

[0076] 6) Determine the degree of dissolution reaction and its impact on carbon dioxide flooding based on the experimental results.

[0077] In one specific embodiment of the present invention, different parameters and phenomena are assigned different weights based on the results of dynamic and static tests, and the results are comprehensively evaluated on-site according to three levels: strong dissolution, moderate dissolution, and weak dissolution, so as to clarify the intensity of the dissolution reaction and its impact on reservoir properties.

[0078] Table 1. Weighting of different experimental test results and assignment of different levels of dissolution.

[0079]

[0080] Based on different experimental results and weights, a comprehensive judgment coefficient η for dissolution intensity is proposed and calculated according to the following formula:

[0081] η i =ω i δ1+χ i δ2+λ i δ3+∑ΔE i (r)δ4

[0082] η i χ² is the comprehensive judgment coefficient for dissolution intensity. iThe results of the corrosion determination are based on scanning electron microscopy (SEM) images; δ1 is the weighting coefficient for dry weight change rate; δ2 is the weighting coefficient for SEM contrast; δ3 is the weighting coefficient for permeability change rate; and δ4 is the weighting coefficient for cumulative pore size change rate. In a specific embodiment of the present invention, δ1 is assigned a value of 15%, δ2 is assigned a value of 15%, δ3 is assigned a value of 40%, and δ4 is assigned a value of 30%.

[0083] Based on the preceding test and calculation results, a comprehensive evaluation of the dissolution effect is completed according to the following criteria: When the comprehensive evaluation coefficient of dissolution intensity is greater than 70, the carbon dioxide flooding is judged as a strong dissolution effect; when the comprehensive evaluation coefficient of dissolution intensity is between 30 and 70, the carbon dioxide flooding is judged as a moderate dissolution effect; when the comprehensive evaluation coefficient of dissolution intensity is less than 30, the carbon dioxide flooding is judged as a weak dissolution effect.

[0084] Table 2. Comprehensive evaluation coefficient and corrosion level classification results

[0085] Greater than 70 Strong dissolution 30-70 Moderate dissolution Less than 30 Weak dissolution

[0086] This method can assess the intensity of dissolution during carbon dioxide flooding in reservoirs with different mineral contents and under different formation pressure conditions.

[0087] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. Those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A comprehensive testing method for reservoir properties under dissolution during carbon dioxide flooding in tight oil reservoirs, characterized in that, Includes the following steps: 1) Select core wells within the target tight oil reservoir area to obtain natural rock cores as test samples; based on the chemical formula of the reaction between carbon dioxide and rock minerals, determine the characteristic mineral component types of the dissolution reaction of the target tight oil reservoir and test the content of dissolution mineral components in the natural rock cores to complete the test of the material basis of the dissolution reaction in the carbon dioxide flooding process. 2) At the target tight reservoir temperature, test the pH value of formation water with carbon dioxide introduced at different pressures to complete the reaction condition test of the dissolution reaction during the carbon dioxide flooding process. Step 2) specifically involves: rinsing the calibrated pressure-resistant electrode with deionized water, loading formation water from the target reservoir into the high-pressure pH testing device, and inserting the pH electrode; preheating the test solution to the specified temperature, and then introducing carbon dioxide gas to the specified pressure; subsequently, gradually increasing the pressure and recording the equilibrium reading displayed on the pH meter at each pressure point. 3) The dry weight of natural cores before and after carbon dioxide flooding under different pressures was tested by weighing method; and the surface images of natural cores before and after carbon dioxide flooding under different pressures were scanned by scanning electron microscopy; the dry weight of the samples and the surface images of the samples before and after carbon dioxide flooding under different pressures were compared to calculate the rate of change of core dry weight and core porosity. 4) Test the porosity and permeability of natural cores before and after carbon dioxide flooding under different pressures. At the same time, conduct nuclear magnetic resonance tests on the cores before and after gas injection under different pressures to obtain T2 spectra under different pressures, and calculate the pore throat radius based on the T2 spectra. 5) The influence of dissolution on reservoir properties is characterized by changes in core dry weight, core surface porosity (SEM) surface porosity, core permeability, and pore throat radius distribution. Step 5) specifically involves: 5-1) Utilizing the rate of change in sample mass before and after the carbon dioxide reaction Quantitative characterization of the degree of static dissolution reaction: ； in, The mass change rate of the sample after it undergoes a dissolution reaction with carbon dioxide; The mass of the sample before it undergoes the dissolution reaction with carbon dioxide; The mass of the sample after it undergoes a dissolution reaction with carbon dioxide; 5-2) The change rate of porosity in samples before and after carbon dioxide reaction is used to characterize the influence of static dissolution on the reservoir pore-throat structure. ； The change rate of porosity after the sample undergoes a dissolution reaction with carbon dioxide; The porosity of the sample before it undergoes a dissolution reaction with carbon dioxide; The porosity of the sample after it undergoes a dissolution reaction with carbon dioxide. 5-3) The degree of dynamic dissolution reaction is quantitatively characterized by the rate of change in sample permeability before and after carbon dioxide flooding: ； in, This represents the rate of change in gas permeability after the sample undergoes a dissolution reaction with carbon dioxide. The gas permeability is measured before the sample undergoes a dissolution reaction with carbon dioxide. The gas permeability is measured after the sample undergoes a dissolution reaction with carbon dioxide. 5-4) Based on the T2 diagrams of the samples before and after carbon dioxide flooding, and the conversion relationship between pore size and T2, the changes in pore size of the core samples before and after carbon dioxide flooding were obtained: ； ； in, The difference in relaxation signal amplitude of the core sample with pore size r before and after gas injection; The amplitude of the relaxation signal of the core sample with pore size r before gas injection; The amplitude of the relaxation signal is given by the core sample with pore size r. It is the difference in relaxation signal amplitude of the core sample with pore size r before and after gas injection. The ratio of the cumulative values ​​of relaxation signal amplitudes for different apertures before gas drive. This represents the cumulative value of the relaxation signal amplitude for different apertures before gas drive; 6) Based on the results of dynamic and static tests, different weights are assigned to different parameters and phenomena. The results are comprehensively evaluated on-site according to three levels: strong dissolution, moderate dissolution, and weak dissolution, so as to clarify the intensity of the dissolution reaction and its impact on reservoir properties. The comprehensive judgment coefficient for dissolution intensity is: ； The comprehensive judgment coefficient for dissolution intensity; This is the weighting coefficient for the rate of change of dry weight; For scanning electron microscopy contrast weighting coefficients; This is the weighting coefficient for the rate of change in penetration rate; This is the weighting coefficient for the cumulative aperture change rate; The value is assigned to 15%. The value is assigned to 15%. The value is assigned to 40%. The value is assigned to 30%; When the comprehensive determination coefficient of the corrosion intensity is greater than 70, the carbon dioxide flooding is determined to be a strong corrosion effect; when the comprehensive determination coefficient of the corrosion intensity is between 30 and 70, the carbon dioxide flooding is determined to be a moderate corrosion effect; when the comprehensive determination coefficient of the corrosion intensity is less than 30, the carbon dioxide flooding is determined to be a weak corrosion effect. The method is used to assess the intensity of dissolution during carbon dioxide flooding under different mineral content reservoirs and formation pressure conditions.

2. The test method according to claim 1, characterized in that, In step 1), the chemical formula for the reaction of carbon dioxide with rocks and minerals includes: The dissolution process of calcite and dolomite: ; The dissolution process of Changbai Stone: .

3. The test method according to claim 1, characterized in that, Step 3) specifically refers to: 3-1) After pretreatment of the sample according to the requirements of scanning electron microscopy test, obtain the scanning electron microscope image and dry weight before carbon dioxide displacement; 3-2) Place the sample into a high-temperature, high-pressure visual autoclave containing deionized water, preheat the solution to the reservoir temperature, then introduce carbon dioxide gas to the specified pressure. After the dissolution reaction is fully completed, remove the sample and obtain the core scanning electron microscope image and dry weight under that pressure. 3-3) Following the method in step 3-2), test the scanning electron microscope images and dry weight of the samples after they undergo a dissolution reaction with carbon dioxide under different pressures; 3-4) Compare the dry weight of samples under different pressures and calculate the rate of change of core dry weight; divide the area of ​​the pores in the scanning electron microscope window by the area of ​​the entire scanning electron microscope window to calculate the porosity of the pore throat on the core surface; compare the porosity of the pore throat on the core surface under different pressures and calculate the rate of change of the pore throat on the core surface.

4. The test method according to claim 1, characterized in that, The specific steps for calculating the pore throat radius in step 4) are as follows: Nuclear magnetic resonance (NMR) tests are conducted on the core before and after gas injection under different pressures to obtain T2 spectra at different pressures. Based on the NMR principle that the relaxation time is proportional to the pore radius, the relaxation time is converted into the pore radius. In the formula: r is the pore radius; T2 is the nuclear magnetic resonance relaxation time; C is the conversion coefficient; and n is the exponent.

5. A system for implementing a comprehensive testing method for reservoir properties under dissolution during the carbon dioxide flooding process in tight oil reservoirs as described in claim 1, characterized in that, include The core dissolution mineral component analysis module is used to obtain the natural core of the target oil reservoir. Based on the chemical formula of the reaction between carbon dioxide and rock minerals, it determines the characteristic mineral component types of the dissolution reaction of the target oil reservoir and tests the content of dissolution mineral components in the core of the target oil reservoir. The formation water pH testing module is used to test the pH value of saturated formation water with dissolved carbon dioxide at different pressures under target reservoir temperatures. The core dry weight change rate calculation module is used to test and compare the dry weight of samples before carbon dioxide flooding under different pressures using the weighing method, thereby calculating the core dry weight change rate. The core pore throat variation calculation module is used to scan and compare images of the sample surface before and after carbon dioxide flooding under different pressures using a scanning electron microscope, thereby calculating the core porosity. The core porosity and permeability detection module is used to detect the porosity and permeability of samples before and after carbon dioxide flooding under different pressures; The nuclear magnetic resonance module is used to conduct nuclear magnetic resonance tests on cores before and after gas injection under different pressures, obtain T2 spectra under different pressures, and calculate the pore throat radius based on the T2 spectra.

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