A method and system for dynamically characterizing injection efficiency of carbon dioxide flooding in an oil reservoir

Abstract

The application discloses a kind of oil layer carbon dioxide drive injection gas efficiency dynamic characterization method and system, comprising the following steps: 1) establish carbon dioxide drive injection gas efficiency dynamic change prediction model;2) carry out the volume expansion experiment after dissolving carbon dioxide under different pressures of crude oil, obtain the volume expansion change coefficient quantitative characterization formula of crude oil under different injection carbon dioxide amount;3) obtain the key static parameters such as compressibility of crude oil, rock compressibility and saturation content;4) obtain the data such as cumulative injection amount, injection-production ratio and block average formation pressure of target reservoir at different times;5) complete injection gas efficiency characterization, obtain the injection gas efficiency result under different injection amount conditions.The application has the advantages of high efficiency and science, and has positive significance for further understanding and improving carbon dioxide drive effect.

Description

Technical Field

[0001] This invention relates to the field of CCUS technology in oil and gas field development, specifically to a method and system for dynamic characterization of the effectiveness of carbon dioxide flooding and gas injection in oil reservoirs. Background Technology

[0002] Carbon dioxide capture, utilization, and storage (CCUS) technology, as an anthropogenic carbon reduction measure, is a focus of attention in the energy industry. CCUS-EOR (carbon dioxide enhanced oil recovery via oil displacement) is an enhanced oil recovery technology that uses carbon dioxide to drive oil flow. Therefore, the development of CCUS-EOR technology is of great significance, especially in unconventional reservoirs such as low-permeability tight oil and shale oil, where its application prospects are broad. However, current field tests commonly show that carbon dioxide is absorbed in non-target layers and sections, particularly in dry layers, water layers, and tight interlayers and interlayers (non-oil sections) between small oil layers. This reduces the amount of carbon dioxide absorbed in the target layer, causing the carbon dioxide flooding effect to fail to meet the design requirements. How to dynamically evaluate the effectiveness of carbon dioxide flooding injection and propose adjustment measures is a pressing technical challenge that needs to be addressed.

[0003] Currently, the effectiveness of carbon dioxide flooding is typically evaluated using reservoir numerical simulation methods. However, these methods require meticulous geological modeling, precise input of reservoir fluid properties, and extensive reservoir history fitting. This process necessitates the collection and processing of large amounts of basic static and dynamic data. Furthermore, the accuracy of the predictions depends not only on the accuracy of the basic data but is also influenced by the subjectivity of history fitting and is characterized by a long timeframe. In geological modeling, dry layers, water layers, and tight interlayers are typically assigned extremely low permeability values ​​and considered ineffective reservoirs. However, carbon dioxide differs significantly from water injection; its strong injection capacity allows for a certain amount of gas uptake even in dry layers, water layers, and tight interlayers. Simultaneously, the highly corrosive nature of carbon dioxide leads to wellbore failures and unpredictable faults, resulting in frequent cross-layer gas channeling. Therefore, there is an urgent need to explore an efficient and rapid method for evaluating the effectiveness of carbon dioxide flooding.

[0004] Therefore, by combining actual reservoir properties and measured formation pressure retention levels after gas injection, a mathematical model of theoretical formation pressure retention level and carbon dioxide flooding gas injection efficiency based on material balance and considering the solubility of carbon dioxide flooding was established. This model enables dynamic characterization of reservoir gas injection efficiency at different gas injection stages and has positive significance for further understanding and improving the effect of carbon dioxide flooding. Summary of the Invention

[0005] To address the issue that non-target layer gas intake in existing carbon dioxide flooding processes leads to suboptimal gas flooding performance, this invention provides a method and system for dynamically characterizing the efficiency of carbon dioxide flooding gas injection in oil reservoirs.

[0006] This invention first provides a method for characterizing the effectiveness of carbon dioxide injection, comprising the following steps:

[0007] 1) Establish a dynamic change characterization model for the effectiveness of carbon dioxide injection and gas displacement based on the influencing factors during the development of the target reservoir; the influencing factors include the injection-production ratio and changes in crude oil volume expansion;

[0008] 2) Conduct experiments on the volume expansion of crude oil obtained from the target reservoir after dissolving carbon dioxide under different pressures, and obtain a quantitative characterization formula for the coefficient of change of crude oil volume expansion after injecting different amounts of carbon dioxide.

[0009] 3) Obtain the static and dynamic parameters of the target reservoir, and calculate the injection-production ratio and the actual injected carbon dioxide subsurface hydrocarbon pore volume of the target reservoir;

[0010] 4) Substitute the quantitative characterization formula, static parameters, dynamic parameters, injection-production ratio, and carbon dioxide underground hydrocarbon pore volume obtained in steps 2) and 3) into the dynamic change characterization model of carbon dioxide injection efficiency constructed in step 1) to obtain the injection efficiency results under different injection volume conditions.

[0011] As a preferred embodiment of the present invention, the dynamic change characterization model of the carbon dioxide injection efficiency in step 1) is specifically as follows:

[0012]

[0013] in, To improve the efficiency of gas injection, and The formation pressure remained horizontal before and after gas injection, respectively. The original formation pressure of the target reservoir. The compression coefficient of crude oil. The core pore volume compressibility coefficient; This represents the water saturation of the formation before gas injection. This represents the actual injected carbon dioxide pore volume of underground hydrocarbons. The coefficient for the change in crude oil volume expansion under different amounts of injected carbon dioxide is a variable related to the amount of carbon dioxide injected. This represents the oil saturation of the formation before gas injection. This represents the cumulative injection-production ratio.

[0014] As a preferred embodiment of the present invention, step 2) includes the following steps:

[0015] 2.1) Obtain crude oil from the target reservoir and inject it into the PVT reactor. Heat the crude oil to the target reservoir temperature, slowly increase the pressure to the formation pressure, and record the volume V of the crude oil in the PVT reactor after stabilizing for 1-2 hours. o ;

[0016] 2.2) Inject carbon dioxide of a preset concentration q into the PVT reactor in step 2.1). When the carbon dioxide can be completely dissolved in the crude oil under the formation pressure, test the volume of the formation crude oil with dissolved carbon dioxide concentration q. If the formation pressure cannot completely dissolve the carbon dioxide, increase the pressure until the carbon dioxide is completely dissolved in the crude oil, and test the volume of the formation crude oil with dissolved carbon dioxide concentration q. After stabilizing for 1-2 hours, record the volume V1 of the crude oil, and calculate B according to B=V1 / V. o Calculate the volume expansion coefficient of crude oil with dissolved carbon dioxide concentration q; 2.3) Inject carbon dioxide concentration q into the PVT reactor again, and calculate the volume expansion coefficient of crude oil with dissolved carbon dioxide concentration 2q according to the operation in step 2.2);

[0017] 2.4) Repeat step 2.3) multiple times to obtain multiple sets of crude oil volume expansion coefficients with different dissolved carbon dioxide amounts, establish a crude oil volume expansion coefficient characterization map, and obtain a quantitative characterization formula for the crude oil volume expansion change coefficient after different injected carbon dioxide amounts.

[0018] The present invention also provides a dynamic characterization system for the efficiency of carbon dioxide flooding and gas injection in oil reservoirs for implementing the above-mentioned dynamic characterization method for the efficiency of carbon dioxide flooding and gas injection in oil reservoirs, comprising:

[0019] The model building module is used to establish a dynamic change characterization model of carbon dioxide flooding and gas injection efficiency based on the influencing factors in the development process of the target reservoir.

[0020] The crude oil volume expansion coefficient characterization module is used to establish a crude oil volume expansion coefficient characterization map based on the obtained volume expansion coefficients of formation crude oil with different dissolved carbon dioxide contents, and to obtain a quantitative characterization formula for the crude oil volume expansion coefficient after different injected carbon dioxide contents.

[0021] The parameter acquisition module is used to acquire the static and dynamic parameters of the target reservoir and calculate the injection-production ratio and the actual injected carbon dioxide underground hydrocarbon pore volume of the target reservoir.

[0022] The gas injection efficiency result acquisition module is used to substitute the static parameters, dynamic parameters, injection-production ratio, actual injected carbon dioxide underground hydrocarbon pore volume, and crude oil volume expansion coefficient under different injected carbon dioxide amounts into the dynamic change characterization model of carbon dioxide flooding gas injection efficiency to obtain gas injection efficiency results under different gas injection volume conditions.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] This invention addresses the issue of suboptimal gas drive performance in existing carbon dioxide flooding processes due to non-target layer gas intake. The key challenge lies in the difficulty and low efficiency of evaluating gas injection effectiveness. This invention innovatively utilizes the principle of material balance, combined with experimental results of dissolved gas-crude oil volume expansion after carbon dioxide flooding, and considers the production injection-production ratio during actual gas injection. It establishes a dynamic prediction model for the effectiveness of carbon dioxide flooding under different injection volumes and injection-production ratios. This method requires only basic fluid properties, injection-production ratio, and actual pressure data to achieve dynamic evaluation of carbon dioxide flooding injection effectiveness. It possesses advantages of high efficiency and scientific rigor, and is of positive significance for further understanding and improving the effectiveness of carbon dioxide flooding. Attached Figure Description

[0025] Figure 1 A schematic diagram illustrating the regression of quantitative formulas for different injected carbon dioxide amounts and the crude oil volume expansion coefficient.

[0026] Figure 2 A schematic diagram of the efficiency characterization curve for carbon dioxide-driven gas injection.

[0027] Figure 3 This is a dynamic data table after carbon dioxide flooding. Detailed Implementation

[0028] 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.

[0029] The present invention describes a method and system for dynamic characterization of the effectiveness of carbon dioxide flooding gas injection in oil reservoirs.

[0030] This innovative approach utilizes the principle of material balance, combined with experimental results on the volume expansion of crude oil after carbon dioxide flooding (COD) injection, and considers the production injection-production ratio and formation pressure maintenance during actual injection processes. A dynamic characterization model for the efficiency of COD injection under different injection volumes and injection-production ratios is established. This method requires only basic fluid properties, injection-production ratios, and actual pressure data to achieve dynamic characterization of COD injection efficiency. The process includes five steps: 1. Establishing a dynamic characterization model for COD injection efficiency based on material balance; 2. Conducting experiments on the volume expansion of crude oil after dissolving carbon dioxide under different pressures to obtain a quantitative characterization formula for the volume expansion coefficient of crude oil with different injected carbon dioxide volumes; 3. Obtaining key static parameters such as crude oil compressibility, rock compressibility, and saturation content; 4. Obtaining data on the cumulative injection volume, injection-production ratio, and average formation pressure of the target reservoir at different times; 5. Completing the characterization of injection efficiency and proposing suggestions for improvement. The specific steps are as follows:

[0031] 1) Establish a dynamic change prediction model for the effectiveness of carbon dioxide injection based on material balance:

[0032] According to the principle of conservation of mass, the change in formation pressure is related to the rate of change of formation volume, and its calculation formula (1) is as follows.

[0033] (1)

[0034] (2)

[0035] The pressure level after gas injection can be calculated according to formula (3).

[0036] (3)

[0037] During water injection development, the volume change rate is mainly affected by the injection-production ratio. However, during carbon dioxide flooding, the volume expansion of crude oil caused by the dissolution of carbon dioxide in the formation is another major factor leading to volume change. The volume change rate of the formation after carbon dioxide flooding is related to the dimensionless volume of crude oil after the volume expansion of dissolved carbon dioxide in the affected area, the dimensionless underground injection volume, and the injection-production ratio. The calculation formula is as follows (4).

[0038] (4)

[0039] In formula (4), the injection-production ratio can be calculated based on the cumulative gas injection volume, water production volume, oil production volume, and carbon dioxide production volume, which is a variable related to the working system. Its calculation formula (5) is as follows:

[0040] (5)

[0041] The volume coefficient of carbon dioxide gas in formula (5) It is usually calculated based on the gas law, and the calculation formula is shown in (6).

[0042] (6)

[0043] In formula (3), the dimensionless volume of crude oil after the volume expansion of dissolved carbon dioxide in the affected area is related to the volume expansion coefficient of crude oil after dissolving carbon dioxide and the saturation level. The calculation formula is shown in formula (7) below.

[0044] (7)

[0045] In the above formula (7), It is the volume expansion coefficient of crude oil after carbon dioxide is dissolved, which is a function of the amount of carbon dioxide dissolved, and can be obtained through carbon dioxide-crude oil gasification expansion experiments. The conversion calculation process between the molar content of carbon dioxide after injection (relative to the entire oil and gas mixture system) and the cumulative underground hydrocarbon volume (HCPV) is shown in the following (8).

[0046] (8)

[0047] Based on formulas (3) and (7), the relationship between the formation pressure level and the injected subsurface volume and injection-production ratio is obtained, and the calculation formula is shown in (9) below.

[0048] (9)

[0049] Based on formula (9), the relationship between the actual intake volume of the target layer and the measured pressure holding level under different pressure holding levels can be obtained. The calculation formula is shown in formula (10) below.

[0050] (10)

[0051] According to formula (10), combined with the actual cumulative underground hydrocarbon pore volume injected, A dynamic mathematical model for the gas injection efficiency under different measured gas injection volumes, combining the actual injection-production ratio and the measured pressure maintenance level, is established. The calculation formula is shown in (11).

[0052] (11)

[0053] In formula (11), the underground volume of the actual gas injection volume can be calculated according to formula (12):

[0054] (12)

[0055] in To improve the efficiency of gas injection, , The formation pressure remained horizontal before and after gas injection, respectively. , , These represent the original formation pressure, the average formation pressure before gas injection, and the average formation pressure after gas injection in the target block or reservoir, respectively. For pressure under standard conditions, , These are the temperatures under standard conditions and the actual reservoir temperatures, respectively. This represents the deviation factor of carbon dioxide under actual reservoir temperature and pressure. To increase formation pressure after gas injection, This represents the rate of change of formation pore volume after gas injection. , , , These are crude oil, formation water, core pore volume, and overall compressibility coefficient, respectively. , The values ​​represent the water saturation and oil saturation of the formation before gas injection. , These represent the actual injected carbon dioxide and the pore volume of underground hydrocarbons absorbed into the target layer, respectively, in HCPV. The volume factor of crude oil after carbon dioxide dissolution is a function related to the amount of carbon dioxide dissolved. The molar content of carbon dioxide after it is injected underground. The cumulative injection-production ratio, This refers to the current effective area of ​​the reservoir or block. This represents the average thickness of the oil layer in the current reservoir or block. This represents the average porosity of the oil reservoir or block. This is the cumulative injection amount. , These represent the cumulative water production and oil production after gas injection, respectively. This represents the cumulative carbon dioxide production after gas injection. This represents the volume factor of carbon dioxide gas under reservoir conditions. , These represent the densities of carbon dioxide and crude oil under reservoir temperature and pressure conditions, respectively. This represents the cumulative injection-production ratio after gas injection. This represents the average relative molecular weight of crude oil.

[0056] 2) In accordance with the industry standard (SY / T5542-2009) "Methods for Fluid Property Analysis of Oil and Gas Reservoirs", gas expansion experiments were conducted to test the relationship between the crude oil volume expansion coefficient and carbon dioxide content, and to obtain a quantitative characterization formula for the change coefficient of crude oil volume expansion with different injected carbon dioxide amounts. The specific steps are as follows:

[0057] 2.1) Obtain the target reservoir formation crude oil, inject a certain amount of formation crude oil into the PVT reactor, heat it to the target reservoir temperature, slowly increase the pressure to the formation pressure, and record the crude oil volume Vo after the system has stabilized for 2 hours.

[0058] 2.2) Inject 10 mol% carbon dioxide into the PVT reactor and observe whether the carbon dioxide can completely dissolve in the crude oil under formation pressure. When it can completely dissolve, test the volume of formation crude oil with 10% dissolved carbon dioxide. Or, if the formation pressure cannot completely dissolve the carbon dioxide, increase the pressure until the carbon dioxide is completely dissolved in the crude oil and test the volume of formation crude oil with 10% dissolved carbon dioxide. After the system stabilizes for 2 hours, record the volume V1 of the crude oil and calculate B according to B=V1 / V. oCalculate the volumetric expansion coefficient of crude oil;

[0059] 2.3) Based on 2.2), inject 10% carbon dioxide into the PVT reactor and test and calculate the volume expansion coefficient of the formation crude oil with 20% dissolved carbon dioxide according to the operation of step 2.2).

[0060] 2.4) Following the procedure in 2.3), inject an additional 10% carbon dioxide into the PVT reactor each time until the carbon dioxide content reaches 90 mol%. Test the volume expansion coefficient of the formation crude oil with different dissolved carbon dioxide contents.

[0061] 2.5) Based on the data obtained from the test in 2.4), construct a graph with carbon dioxide content on the horizontal axis and crude oil volume expansion coefficient on the vertical axis, as shown below. Figure 1 As shown, a quantitative formula characterizing the coefficient of change in crude oil volume expansion with different injected carbon dioxide amounts was obtained through regression analysis. Specifically, by combining actual measured data, regression may yield exponential, logarithmic, and idempotent functions.

[0062] 3) Obtain key static parameters such as crude oil compressibility, rock compressibility, and oil saturation:

[0063] 3.1) Based on the target reservoir reserve report, obtain the average thickness of the original reservoir. ,area Porosity Oil saturation and bound water saturation;

[0064] 3.2) Calculate the oil saturation of the formation before gas injection, based on the cumulative oil production before gas injection. and water saturation ;

[0065] 3.3) Obtain the compressibility coefficient of the crude oil based on the high-pressure physical property report of the target reservoir. and the density of crude oil in the formation ;

[0066] 3.4) The compressibility of the core samples from the target reservoir was tested according to the petroleum and natural gas industry standard SY / T 5815-2016 "Method for Determination of Rock Pore Volume Compressibility" to obtain the rock pore compressibility. .

[0067] 3.5) Based on the current reservoir development plan, obtain the original formation pressure of the target reservoir. Furthermore, it collects well pressure measurement data for the entire target block before production to obtain the average formation pressure before gas injection. Furthermore, by considering reservoir temperature, the carbon dioxide density under thermo-baric conditions was determined. ;

[0068] 4) Obtain dynamic data such as cumulative gas injection volume, injection-production ratio, and average formation pressure of the target reservoir at different times:

[0069] 4.1) Collect and compile the cumulative gas injection volume after gas injection in the target reservoir or block on a semi-annual or annual basis. And convert it into hydrocarbon pore volume according to the following calculation formula;

[0070]

[0071] 4.2) Collect and compile the cumulative gas injection volume after gas injection in the target reservoir or block on a semi-annual or annual basis. Cumulative water output Cumulative oil production Cumulative carbon dioxide production on the ground The cumulative injection-production ratio under formation conditions is calculated using the following formula:

[0072]

[0073] 4.3) Based on the pressure measurement data after gas injection of the target reservoir or block, which is compiled every six months or annually, the mean formation pressure data after gas injection is obtained. Formation pressure is a variable related to the working system.

[0074] 4.4) Organize and plot the collected production dynamic data as follows: Figure 3 The table shown.

[0075] 5) Evaluate the gas injection efficiency under different gas injection volume conditions and propose suggestions for improvement:

[0076] 5.1) Substitute the static parameters and production dynamic parameters obtained in steps 2), 3), and 4) into the mathematical model established in step 1), i.e., formula (11), to calculate the gas injection efficiency of the target layer under different cumulative injection volumes, and complete the dynamic evaluation of gas injection efficiency, such as... Figure 2 As shown, the gas injection efficiency curves under different cumulative gas injection volumes are plotted.

[0077] 5.2) Based on the evaluation results of gas injection efficiency, propose targeted improvement suggestions:

[0078] When the gas injection efficiency is greater than 80%, it indicates that the gas intake of the target layer is good, and the current production system should be maintained to continue production.

[0079] When the gas injection efficiency is between 50% and 80%, it indicates significant gas intake in non-target layers. It is recommended to adjust the injection volume based on the original annual injection volume. Increase the gas injection volume by multiples;

[0080] When the gas injection efficiency is less than 50%, it indicates that gas intake from non-target layers is dominant. It is recommended to re-inspect the wellbore integrity. If casing damage is determined, wellbore treatment or gas injection well replacement should be carried out. If non-casing damage is determined, it confirms that the geological conditions are not suitable for carbon dioxide flooding. It is recommended to stop the test or change to a project mainly focused on storage.

[0081] like Figure 2 As shown, the carbon dioxide injection efficiency of a reservoir under different cumulative injection volumes is quantified. As the injection progresses, the carbon dioxide injection efficiency shows a decreasing trend, but the overall injection efficiency exceeds 80%, indicating that the gas intake of the target layer is good.

[0082] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are relatively 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 method for dynamically characterizing the effectiveness of carbon dioxide flooding gas injection in oil reservoirs, characterized in that, Includes the following steps: 1) Establish a dynamic change characterization model for the efficiency of carbon dioxide flooding and gas injection based on the influencing factors during the development of the target reservoir; the influencing factors include the cumulative injection-production ratio and changes in crude oil volume expansion; the specific dynamic change characterization model for the efficiency of carbon dioxide flooding and gas injection in step 1) is as follows: ； in, To improve the efficiency of gas injection, and The formation pressure remained horizontal before and after gas injection, respectively. The original formation pressure of the target reservoir. The compression coefficient of crude oil. The core pore volume compressibility coefficient; This represents the water saturation of the formation before gas injection. This represents the actual injected carbon dioxide pore volume of underground hydrocarbons. The coefficient for the change in crude oil volume expansion under different amounts of injected carbon dioxide is a variable related to the amount of carbon dioxide injected. This represents the oil saturation of the formation before gas injection. This represents the cumulative injection-production ratio. 2) Conduct experiments on the volume expansion of crude oil obtained from the target reservoir after dissolving carbon dioxide under different pressures, and obtain a quantitative characterization formula for the coefficient of change of crude oil volume expansion after injecting different amounts of carbon dioxide. Step 2) includes the following steps: 21) Obtain crude oil from the target reservoir and inject it into the PVT reactor. Heat the crude oil to the target reservoir temperature, slowly increase the pressure to the formation pressure, and record the volume V of the crude oil in the PVT reactor after stabilizing for 1-2 hours. o ; 22) Inject carbon dioxide of a preset concentration q into the PVT reactor in step 21). When the carbon dioxide can be completely dissolved in the crude oil under the formation pressure, test the volume of the formation crude oil with dissolved carbon dioxide concentration q. If the formation pressure cannot completely dissolve the carbon dioxide, increase the pressure until the carbon dioxide is completely dissolved in the crude oil, and test the volume of the formation crude oil with dissolved carbon dioxide concentration q. After stabilizing for 1-2 hours, record the volume V1 of the crude oil, and calculate B according to B=V1 / V o Calculate the volume expansion coefficient of crude oil with dissolved carbon dioxide concentration q; wherein the molar concentration q of carbon dioxide injected into the PVT reactor each time ranges from 2 mol% to 20 mol%. 23) Inject carbon dioxide of concentration q into the PVT reactor again, and calculate the volume expansion coefficient of crude oil with dissolved carbon dioxide of concentration 2q according to the operation in step 22). 24) Repeat step 23) multiple times to obtain multiple sets of volume expansion coefficients of formation crude oil with different dissolved carbon dioxide amounts, establish a crude oil volume expansion coefficient characterization map, and obtain a quantitative characterization formula for the crude oil volume expansion change coefficient after different injected carbon dioxide amounts. 3) Obtain the static and dynamic parameters of the target reservoir, and calculate the cumulative injection-production ratio and the actual injected carbon dioxide subsurface hydrocarbon pore volume of the target reservoir; 4) Substitute the quantitative characterization formula, static parameters, dynamic parameters, cumulative injection-production ratio, and carbon dioxide underground hydrocarbon pore volume obtained in steps 2) and 3) into the dynamic change characterization model of carbon dioxide injection efficiency constructed in step 1) to obtain the injection efficiency results under different injection volume conditions.

2. The method for dynamically characterizing the effectiveness of carbon dioxide flooding gas injection in oil reservoirs according to claim 1, characterized in that, The static parameters in step 3) include crude oil compressibility coefficient, formation crude oil density, core pore volume compressibility coefficient, formation water saturation before and after gas injection, oil saturation, average oil layer thickness of the target reservoir, effective area, and average porosity of the oil layer.

3. The method for dynamically characterizing the effectiveness of carbon dioxide flooding gas injection in oil reservoirs according to claim 2, characterized in that, Crude oil compressibility coefficient (static parameters) Density of formation crude oil Obtained from the high-pressure physical property report of the crude oil in the target reservoir; Static parameters, core pore volume compressibility The compressibility coefficient was obtained by testing the core samples from the target reservoir.

4. The method for dynamically characterizing the effectiveness of carbon dioxide flooding gas injection in oil reservoirs according to claim 2, characterized in that, The static parameters, including formation water saturation, oil saturation, average oil layer thickness, effective area, and average porosity before and after gas injection, were obtained from the target reservoir reserve report.

5. The method for dynamically characterizing the effectiveness of carbon dioxide flooding gas injection in oil reservoirs according to claim 1, characterized in that, The dynamic parameters mentioned in step 3) include the cumulative gas injection volume, cumulative water production volume, cumulative oil production volume, cumulative carbon dioxide production volume, and formation pressure after gas injection at different times.

6. The method for dynamically characterizing the effectiveness of carbon dioxide flooding gas injection in oil reservoirs according to claim 1, characterized in that, The formula for calculating the actual injected carbon dioxide subsurface hydrocarbon pore volume in the target reservoir is as follows: ； in, This represents the actual injected carbon dioxide pore volume of underground hydrocarbons. The cumulative gas injection volume after gas injection into the target reservoir. The effective area of ​​the target reservoir. The average porosity of the oil layer in the target reservoir. The average thickness of the oil layer in the target reservoir. This represents the water saturation of the formation before gas injection. This represents the density of carbon dioxide under reservoir temperature and pressure conditions.

7. The method for dynamically characterizing the effectiveness of carbon dioxide flooding gas injection in oil reservoirs according to claim 1, characterized in that, The cumulative injection-production ratio is the ratio of the cumulative underground volume of gas injected after injection to the cumulative underground volume of produced oil, gas, and water. The formula for calculating the cumulative injection-production ratio is: ； in, The cumulative gas injection volume after gas injection into the target reservoir. The density of carbon dioxide under reservoir temperature and pressure conditions. The cumulative water production after carbon dioxide injection into the target oil reservoir. The cumulative oil production after carbon dioxide injection into the target reservoir. This represents the cumulative carbon dioxide production on the ground after carbon dioxide injection. is the volume factor of carbon dioxide gas under reservoir conditions. The density of crude oil under reservoir temperature and pressure conditions. This is the crude oil volume coefficient.

8. A dynamic characterization system for the efficiency of carbon dioxide flooding and gas injection in oil reservoirs, used to implement the dynamic characterization method for the efficiency of carbon dioxide flooding and gas injection in oil reservoirs according to any one of claims 1-7, characterized in that, include: The model building module is used to establish a dynamic change characterization model of carbon dioxide flooding and gas injection efficiency based on the influencing factors in the development process of the target reservoir. The crude oil volume expansion coefficient characterization module is used to establish a crude oil volume expansion coefficient characterization map based on the obtained volume expansion coefficients of formation crude oil with different dissolved carbon dioxide contents, and to obtain a quantitative characterization formula for the crude oil volume expansion coefficient after different injected carbon dioxide contents. The parameter acquisition module is used to acquire the static and dynamic parameters of the target reservoir and calculate the cumulative injection-production ratio and the actual injected carbon dioxide underground hydrocarbon pore volume of the target reservoir. The gas injection efficiency result acquisition module is used to substitute the static parameters, dynamic parameters, cumulative injection-production ratio, actual injected carbon dioxide underground hydrocarbon pore volume, and crude oil volume expansion coefficient under different injected carbon dioxide amounts into the dynamic change characterization model of carbon dioxide flooding gas injection efficiency to obtain gas injection efficiency results under different gas injection volume conditions.

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