A method, device, computer storage medium and equipment for calculating effective sealing capacity of carbon dioxide in a constant-volume depleted gas reservoir

Abstract

The application discloses a kind of constant volume exhausted gas reservoir carbon dioxide effective sealing capacity calculation method, comprising: collecting target gas reservoir original geological reserves, production dynamic data, gas reservoir original formation pressure and temperature, high pressure physical property analysis and constant volume depletion test data;Establish the relationship between pseudo pressure and corresponding period cumulative natural gas equivalent production, then draw the intersection plot of target gas reservoir production stage material balance relationship, if the cumulative natural gas equivalent production when pseudo pressure is equal to 0 is consistent with original formation natural gas reserves, then determine that the gas reservoir is constant volume exhausted gas reservoir;Query CO2 deviation factor under CO2 injection to gas reservoir original formation pressure and temperature, and utilize gas reservoir ultimate recovery degree to calculate the mixed gas deviation factor under CO2 injection to gas reservoir original formation pressure;Calculate the injectable amount of CO2 injection to gas reservoir original formation pressure of exhausted gas reservoir;Calculate the CO2 effective sealing capacity of exhausted gas reservoir.The application can reliably calculate the carbon dioxide effective sealing capacity of constant volume exhausted gas reservoir.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide geological storage technology, and more particularly to a method, apparatus, computer storage medium, and equipment for calculating the effective carbon dioxide storage capacity of a fixed-volume depleted gas reservoir based on actual test and production data. Background Technology

[0002] As the world intensifies its efforts to reduce greenhouse gas emissions, CCS (Carbon Capture and Storage) is receiving increasing attention as a safety net for achieving net-zero emissions. A large number of projects utilizing depleted oil and gas reservoirs and saline aquifers for carbon dioxide sequestration have been successfully implemented. Because natural gas has been effectively sealed for a long geological period, these reservoirs possess high caprock integrity and fault sealing properties, and their development and production have access to a wealth of basic data and existing surface production facilities. Therefore, utilizing depleted gas reservoirs for carbon dioxide sequestration is widely recognized as an economical and safe geological sequestration method.

[0003] Accurately understanding the storage capacity of a sequestered geological body is a crucial foundation for source-sink matching planning and sequestration scheme design in CCS projects. Currently, commonly used methods for calculating the carbon dioxide sequestration capacity of oil and gas reservoirs include the Carbon Leaders Forum method (Bachu, 2007) and the US Department of Energy method (Goodman, 2011). However, these methods do not utilize actual production data from oil and gas reservoirs, resulting in poor parameter reliability. They can only be used to calculate theoretical or maximum carbon dioxide sequestration capacity and cannot be applied to calculating the effective carbon dioxide sequestration capacity of depleted gas reservoirs with substantial production data and in the late stages of development. While some published patents involve methods for calculating the sequestration capacity of depleted oil and gas reservoirs—for example, Chinese patent CN116502756 proposes a method for calculating the theoretical maximum carbon dioxide storage capacity of a fixed-volume sealed oil reservoir—this method calculates the theoretical maximum storage capacity, and due to the significant differences in production performance between oil and gas reservoirs, it cannot be applied to calculating the effective carbon dioxide sequestration capacity of depleted gas reservoirs. Chinese patent CN116562126 proposes an optimized design and system for carbon dioxide geological sequestration parameters in depleted gas reservoirs. This method is mainly based on a large amount of reservoir geology and production data, and uses numerical simulation to design sequestration schemes. It is suitable for the later-stage injection scheme design of CCS projects. However, this method has high requirements for the quality and quantity of input data, complex simulation calculations, and high requirements for reservoir expertise and simulation software operation. It cannot be applied to the rapid and effective assessment of carbon dioxide sequestration capacity in depleted gas reservoirs.

[0004] Therefore, to address the above shortcomings, a method is needed to quickly and accurately calculate the effective carbon dioxide sequestration capacity of depleted gas reservoirs in order to obtain a reliable effective carbon dioxide sequestration capacity and support the design of CCS project schemes. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention provides a method for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir, which aims to reliably calculate the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir, comprising the following steps:

[0008] Collect original geological reserves, production dynamics data, original formation pressure and temperature, high-pressure physical property analysis and constant-volume exhaustion test data of the target gas reservoir, and determine the calculation parameters;

[0009] The formation pressure at different stages of gas reservoir production is obtained using dynamic production data. The relationship between the deviation factor and pressure is established using constant-volume depletion test data to obtain the corresponding natural gas deviation factor. The relationship between the pseudo-pressure and the cumulative natural gas equivalent production at the corresponding period is established. Then, a cross-plot of the material balance relationship of the target gas reservoir production stage is drawn. If the cumulative natural gas equivalent production when the pseudo-pressure is equal to 0 is consistent with the original formation natural gas reserves, the influence of water intrusion is excluded, the gas reservoir is determined to be a constant-volume depleted gas reservoir, and the next step is carried out. Otherwise, the method ends.

[0010] Query the CO2 deviation factor at the original formation pressure and temperature of CO2 injection into the gas reservoir, and calculate the mixed gas deviation factor at the original formation pressure of CO2 injection into the gas reservoir using the final recovery degree of the gas reservoir;

[0011] The injectable amount of CO2 into a depleted gas reservoir is calculated using the cumulative natural gas equivalent production, the original formation natural gas reserves, and the mixed gas deviation factor under the original formation pressure of CO2 injection.

[0012] The effective CO2 storage capacity of a depleted gas reservoir is calculated based on the injectable amount of CO2 to the original formation pressure of the reservoir.

[0013] Preferably, the calculation parameters include the raw natural gas production under standard conditions. G i_gas Production of raw condensate oil under standard conditions G i_oil Cumulative natural gas production under standard conditions G p_gas Cumulative condensate production under standard conditions G p_oil Density of condensate oil relative to pure water γ oil The molecular weight of condensate oil relative to pure water M oil; original formation pressure of the gas reservoir p i Original formation temperature of the gas reservoir T r and the natural gas deviation factor under the original formation pressure and temperature of the gas reservoir z i .

[0014] As a preferred embodiment, the relationship between the pseudo-pressure and the corresponding cumulative natural gas equivalent production over the period is as follows:

[0015] (1)

[0016] (2)

[0017] (3)

[0018] In the formula, p gas Formation pressure at different stages during gas reservoir development; z gas This refers to the natural gas deviation factor at different stages of gas reservoir development. p gas / z gas To simulate pressure; G i This represents the original formation natural gas equivalent reserves; G p To accumulate natural gas equivalent production.

[0019] As a preferred embodiment, the mixture deviation factor under the original formation pressure of the injected CO2 is calculated using the following formula:

[0020] (4)

[0021] In the formula, z mix This is the deviation factor for the mixed gas under the original formation pressure of CO2 injection into the gas reservoir; z CO2 The CO2 deviation factor is the CO2 injection into the original formation pressure and temperature of the gas reservoir. R gas To determine the final recovery level of a gas reservoir, the equivalent reserves of natural gas in the original formation are used. G i and cumulative natural gas equivalent production G p The ratio is determined.

[0022] Preferably, the injectable amount of CO2 from the depleted gas reservoir to the original formation pressure is calculated using the following formula:

[0023] (5)

[0024] In the formula, G injCO2 The injectable amount of CO2 to be injected into a depleted gas reservoir to the original formation pressure of the reservoir; p mix This refers to the formation pressure of the gas reservoir after CO2 injection. p mix = p i .

[0025] As a preferred embodiment, the effective CO2 sequestration capacity of the depleted gas reservoir is calculated using the following formula:

[0026] (6)

[0027] In the formula, Effective CO2 sequestration capacity of depleted gas reservoirs; This represents the CO2 density under standard conditions.

[0028] Secondly, the present invention provides a calculation device for the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir, characterized in that it comprises:

[0029] The first processing unit is used to collect the original geological reserves of the target gas reservoir, production dynamic data, original formation pressure and temperature of the gas reservoir, high pressure physical property analysis and constant volume exhaustion test data, and to determine the calculation parameters.

[0030] The second processing unit is used to obtain the formation pressure at different stages of the gas reservoir production process using production dynamic data, and to obtain the corresponding natural gas deviation factor by using the relationship between the deviation factor and pressure established by the constant volume depletion test data. It also establishes the relationship between the pseudo pressure and the cumulative natural gas equivalent production at the corresponding period, and then draws the cross-plot of the material balance relationship of the target gas reservoir production stage. If the cumulative natural gas equivalent production when the pseudo pressure is equal to 0 is consistent with the original formation natural gas reserves, then the influence of water intrusion is excluded, and the gas reservoir is determined to be a constant volume depletion gas reservoir.

[0031] The third processing unit is used to query the CO2 deviation factor at the original formation pressure and temperature of CO2 injection into the gas reservoir, and to calculate the mixed gas deviation factor at the original formation pressure of CO2 injection into the gas reservoir using the final recovery degree of the gas reservoir.

[0032] The fourth processing unit is used to calculate the injectable amount of CO2 into a depleted gas reservoir up to the original formation pressure using accumulated natural gas equivalent production, original formation natural gas reserves, and the mixing gas deviation factor under CO2 injection to the original formation pressure of the gas reservoir.

[0033] The fifth processing unit is used to calculate the effective CO2 storage capacity of a depleted gas reservoir based on the injectable amount of CO2 injected into the reservoir's original formation pressure.

[0034] Thirdly, the present invention provides a computer-readable storage medium, characterized in that it stores a computer program, which is executed by a processor to control the device where the processor is located to implement the steps of the method for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir as described in the first aspect of the present invention.

[0035] Fourthly, the present invention provides a computer device, characterized in that it includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir as described in the first aspect of the present invention.

[0036] The present invention has the following advantages due to the adoption of the above technical solutions:

[0037] This invention establishes a method for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir based on actual test and production data. It establishes a functional relationship between CO2 injection rate and formation pressure, gas deviation factor and oil and gas production through the principle of material balance, and provides a method for quickly calculating the mixed gas deviation factor after CO2 injection, which can reliably calculate the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir. Attached Figure Description

[0038] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:

[0039] Figure 1 A cross-plot of the mass balance relationships during the production phase of the target gas reservoir;

[0040] Figure 2 This is a cross-plot comparing the material balance relationship during the CO2 injection stage with the material balance relationship during the production stage of the target gas reservoir. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments of the present invention will be further described below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0042] The present invention provides a method for calculating the effective carbon dioxide sequestration capacity of a constant-volume depleted gas reservoir, comprising: collecting original geological reserves, production dynamic data, original formation pressure and temperature, high-pressure property analysis, and constant-volume depletion test data of the target gas reservoir; establishing a relationship between the simulated pressure and the cumulative natural gas equivalent production at the corresponding period, and then plotting a cross-plot of the material balance relationship of the target gas reservoir at the production stage; if the cumulative natural gas equivalent production at the simulated pressure equal to 0 is consistent with the original formation natural gas reserves, then the gas reservoir is determined to be a constant-volume depleted gas reservoir; querying the CO2 deviation factor at the original formation pressure and temperature for CO2 injection, and calculating the mixed gas deviation factor at the original formation pressure for CO2 injection using the final recovery degree of the gas reservoir; calculating the injectable amount of CO2 in the depleted gas reservoir at the original formation pressure; and calculating the effective CO2 sequestration capacity of the depleted gas reservoir. The present invention can reliably calculate the effective carbon dioxide sequestration capacity of a constant-volume depleted gas reservoir.

[0043] The following is a detailed description, with reference to the accompanying drawings, of the method and apparatus for calculating the effective carbon dioxide sequestration capacity of a depleted gas reservoir at constant volume, as provided in the embodiments of the present invention.

[0044] Example 1:

[0045] This embodiment provides a method for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir, including the following steps:

[0046] S100. Collect original geological reserves, production dynamics data, original formation pressure and temperature, high-pressure physical property analysis, and constant-volume depletion test data of the target gas reservoir to determine calculation parameters; among which, the calculation parameters include the original natural gas production under standard conditions. G i_gas Production of raw condensate oil under standard conditions G i_oil Cumulative natural gas production under standard conditions G p_gas Cumulative condensate production under standard conditions G p_oil Density of condensate oil relative to pure water γ oil The molecular weight of condensate oil relative to pure water M oil ; original formation pressure of the gas reservoir p i Original formation temperature of the gas reservoir T r and the natural gas deviation factor under the original formation pressure and temperature of the gas reservoir z i .

[0047] S200. Formation pressure at different stages of gas reservoir production is obtained using production dynamic data, and the corresponding natural gas deviation factor is obtained using the relationship between the deviation factor and pressure established from constant-volume depletion test data. A pseudo-pressure (i.e., p) is then established. gas / z gas The relationship between the cumulative natural gas equivalent production and the corresponding period is established, and a cross-plot of the material balance relationship of the target gas reservoir's production stage is plotted. If the cumulative natural gas equivalent production at the simulated pressure of 0 is consistent with the original formation natural gas reserves, then the influence of water intrusion can be ruled out, the gas reservoir is determined to be a constant-volume depleted gas reservoir, and the process proceeds to the next step; otherwise, the method ends. p gas / z gas The relationship between the cumulative natural gas equivalent production for the corresponding period is as follows:

[0048] (1)

[0049] In the formula, p gas Formation pressure at different stages during gas reservoir development; z gas This refers to the natural gas deviation factor at different stages of gas reservoir development. G i This represents the original formation natural gas equivalent reserves; G p To accumulate natural gas equivalent production.

[0050] Among them, the original formation natural gas reserves G i and cumulative natural gas equivalent production G p They can be represented as:

[0051] (2)

[0052] (3)

[0053] S300. Query the CO2 deviation factor at the original formation pressure and temperature of CO2 injection into the gas reservoir, and calculate the mixed gas deviation factor at the original formation pressure of CO2 injection into the gas reservoir using the following formula based on the final recovery degree of the gas reservoir.

[0054] (4)

[0055] In the formula, z mix This is the deviation factor for the mixed gas under the original formation pressure of CO2 injection into the gas reservoir; z CO2 The CO2 deviation factor is the CO2 injection into the original formation pressure and temperature of the gas reservoir. Rgas To determine the final recovery level of a gas reservoir, the equivalent reserves of natural gas in the original formation are used. G i and cumulative natural gas equivalent production G p The ratio is determined.

[0056] S400. Using the cumulative natural gas equivalent production, original formation natural gas reserves from step S200, and the mixed gas deviation factor under the original formation pressure of CO2 injection from step S300, the injectable amount of CO2 to the original formation pressure of the depleted gas reservoir is calculated using the following formula:

[0057] (5)

[0058] In the formula, G injCO2 The injectable amount of CO2 to be injected into a depleted gas reservoir to the original formation pressure of the reservoir; p mix This refers to the formation pressure of the gas reservoir after CO2 injection. p mix = p i .

[0059] S500. Based on the injectable CO2 volume to the original formation pressure of the depleted gas reservoir obtained in step S400, the effective CO2 storage capacity of the depleted gas reservoir is calculated using the following formula:

[0060] (6)

[0061] In the formula, Effective CO2 sequestration capacity of depleted gas reservoirs; This represents the CO2 density under standard conditions.

[0062] In the above embodiments, preferably, the following steps may also be included:

[0063] S600. Calculate the injectable CO2 from 0 to the injectable amount calculated in step S400 using the following formula (7). p mix / z mix ， draw p mix / z mix and G p -G injCO2 The intersection diagram, and the one in step S200 p gas / z gas —G p By merging the cross plots, the reliability of the calculated effective carbon dioxide sequestration capacity of a depleted gas reservoir at constant volume can be further verified. Theoretically, the trend lines of the two plots should be basically consistent.

[0064] (7)

[0065] The following specific example illustrates the calculation method for the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir according to the present invention, including the following steps:

[0066] Step 1: Based on the original geological reserves, production dynamics data, original formation pressure and temperature, high-pressure property analysis, and constant-volume depletion test data of the target gas reservoir, the final shutdown time of the gas reservoir can be determined. G i_gas 、G i_oil 、G p_gas 、G p_oil 、p i 、T r 、z i 、 γ oil 、M oil The final shutdown time of the gas reservoir can be calculated using equations (2) and (3). G i 、G p and through G p and G i The ratio can be determined R gas ， The relevant calculation parameters are shown in Table 1.

[0067] Table 1 Calculation Parameter Table

[0068]

[0069] Step 2: Obtain formation pressure at different stages of gas reservoir production using production dynamic data. p gas and corresponding cumulative natural gas equivalent production G p The corresponding natural gas deviation factor was obtained by using the relationship between the deviation factor and pressure established from the constant volume depletion test data. z gas The relevant data is shown in Table 2. pgas / z gas Cumulative natural gas equivalent production during the corresponding period G p The relationship, and draw it. p gas / z gas and G p Intersection diagram (see) Figure 1 ). p gas / z gas and G p The fitted relationship is linear. p gas / z gas =0 G p 16.01×10 8 m 3 The results are very close to the original geological reserves, with an error of 2%, indicating that the gas reservoir is a water-free, constant-volume, closed gas reservoir.

[0070] Table 2 Formation pressure, deviation factor, and corresponding production at the production stage of the target gas reservoir

[0071]

[0072] Step 3: Check the original formation pressure of the gas reservoir after CO2 injection. p i and temperature T r CO2 deviation factor z CO2 The value is 0.5561. Equation (4) is used to calculate the mixing gas deviation factor under the original formation pressure of the gas reservoir after CO2 injection following the shutdown of the gas reservoir. z mix It is 0.6678.

[0073] Step 4: Calculate the injectable CO2 volume to the original formation pressure of the depleted gas reservoir using equation (5). At this point, p mix = p i , can be obtained G injCO2 13.65×10 8 m 3 .

[0074] Step 5: Calculate the effective carbon dioxide sequestration capacity of the depleted gas reservoir using equation (6). M injCO2It was 2.5566 million tons, ρ CO2 Take 1.873 kg / m 3 .

[0075] Step 6: Calculate the CO2 injection to 13.65 × 10 using equation (7). 8 m 3 of p mix / z mix ， draw p mix / z mix and G p -G injCO2 Intersection diagram ( G p The cumulative natural gas equivalent production at the time of final shutdown of the gas reservoir G p 9.67×10 8 m 3 The cumulative natural gas equivalent production from the start of gas reservoir production to final shutdown is calculated using the material balance fitting formula from step 2. G p 9.67×10 8 m 3 of p gas / z gas Draw on the same intersection diagram p gas / z gas and G p Intersection diagram (see also) Figure 2 It can be seen that the CO2 injection stage p mix / z mix and G p -G injCO2 Relationship Trends and Gas Reservoir Production Stages p gas / z gas and G p The consistent trend indicates that the CO2 calculation results for this constant-volume depleted gas reservoir are reliable.

[0076] Example 2:

[0077] The above-described embodiment 1 provides a method for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir. Correspondingly, this embodiment provides a device for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir. The calculation device provided in this embodiment can implement the calculation method of embodiment 1. This calculation device can be implemented through software, hardware, or a combination of both. For example, the calculation device may include integrated or separate functional modules or functional units to execute the corresponding steps in the methods of embodiment 1. Since the calculation device in this embodiment is basically similar to the method embodiment, the description process in this embodiment is relatively simple. Relevant details can be found in the description of embodiment 1. The calculation device in this embodiment is merely illustrative.

[0078] The device for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir provided in this embodiment includes:

[0079] The first processing unit is used to collect the original geological reserves of the target gas reservoir, production dynamic data, original formation pressure and temperature of the gas reservoir, high pressure physical property analysis and constant volume exhaustion test data, and to determine the calculation parameters.

[0080] The second processing unit is used to obtain the formation pressure at different stages of the gas reservoir production process using production dynamic data, and to obtain the corresponding natural gas deviation factor by using the relationship between the deviation factor and pressure established by the constant volume depletion test data. It also establishes the relationship between the pseudo pressure and the cumulative natural gas equivalent production at the corresponding period, and then draws the cross-plot of the material balance relationship of the target gas reservoir production stage. If the cumulative natural gas equivalent production when the pseudo pressure is equal to 0 is consistent with the original formation natural gas reserves, then the influence of water intrusion is excluded, and the gas reservoir is determined to be a constant volume depletion gas reservoir.

[0081] The third processing unit is used to query the CO2 deviation factor at the original formation pressure and temperature of CO2 injection into the gas reservoir, and to calculate the mixed gas deviation factor at the original formation pressure of CO2 injection into the gas reservoir using the final recovery degree of the gas reservoir.

[0082] The fourth processing unit is used to calculate the injectable amount of CO2 into a depleted gas reservoir up to the original formation pressure using accumulated natural gas equivalent production, original formation natural gas reserves, and the mixing gas deviation factor under CO2 injection to the original formation pressure of the gas reservoir.

[0083] The fifth processing unit is used to calculate the effective CO2 storage capacity of a depleted gas reservoir based on the injectable amount of CO2 injected into the reservoir's original formation pressure.

[0084] Example 3:

[0085] This embodiment provides a processing device for implementing the calculation method for the effective carbon dioxide sequestration capacity of a depleted gas reservoir provided in Embodiment 1. The processing device can be a client-side processing device, such as a mobile phone, laptop, tablet computer, or desktop computer, to execute the method of Embodiment 1.

[0086] The processing device includes a processor, a memory, a communication interface, and a bus. The processor, memory, and communication interface are connected via the bus to enable communication between them. The memory stores a computer program that can run on the processor. When the processor runs the computer program, it executes the calculation method provided in Embodiment 1.

[0087] Preferably, the memory may be high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage device.

[0088] Preferably, the processor can be any type of general-purpose processor such as a central processing unit (CPU) or a digital signal processor (DSP), and there is no limitation herein.

[0089] Example 4:

[0090] The method for calculating the effective carbon dioxide sequestration capacity of a depleted gas reservoir in this embodiment 1 can be specifically implemented as a computer program product. The computer program product may include a computer-readable storage medium on which computer-readable program instructions for executing the method described in this embodiment 1 are loaded.

[0091] A computer-readable storage medium can be a tangible device that holds and stores instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir, characterized in that, Includes the following steps: Collect original geological reserves, production dynamics data, original formation pressure and temperature, high-pressure physical property analysis and constant-volume exhaustion test data of the target gas reservoir, and determine the calculation parameters; The formation pressure at different stages of gas reservoir production is obtained using dynamic production data. The relationship between the deviation factor and pressure is established using constant-volume depletion test data to obtain the corresponding natural gas deviation factor. The relationship between the pseudo-pressure and the cumulative natural gas equivalent production at the corresponding period is established. Then, a cross-plot of the material balance relationship of the target gas reservoir production stage is drawn. If the cumulative natural gas equivalent production when the pseudo-pressure is equal to 0 is consistent with the original formation natural gas reserves, the influence of water intrusion is excluded, the gas reservoir is determined to be a constant-volume depleted gas reservoir, and the next step is performed. Otherwise, the method ends. Query the CO2 deviation factor at the original formation pressure and temperature of CO2 injection into the gas reservoir, and calculate the mixed gas deviation factor at the original formation pressure of CO2 injection into the gas reservoir using the final recovery degree of the gas reservoir; The injectable amount of CO2 into a depleted gas reservoir is calculated using the cumulative natural gas equivalent production, the original formation natural gas reserves, and the mixed gas deviation factor under the original formation pressure of CO2 injection. The effective CO2 storage capacity of a depleted gas reservoir is calculated based on the injectable amount of CO2 injected into the reservoir to the original formation pressure. The injectable amount of CO2 from the depleted gas reservoir to the original formation pressure is calculated using the following formula: （5） In the formula, G injCO2 The injectable amount of CO2 to be injected into a depleted gas reservoir to the original formation pressure of the reservoir; p mix This refers to the formation pressure of the gas reservoir after CO2 injection. p mix = p i ;z mix This is the deviation factor for the mixed gas under the original formation pressure of CO2 injection into the gas reservoir; z i This represents the natural gas deviation factor based on the original formation pressure and temperature of the gas reservoir. p i This represents the original formation pressure of the gas reservoir. G p To accumulate natural gas equivalent production; G i This represents the original formation natural gas equivalent reserves.

2. The calculation method according to claim 1, characterized in that, The calculation parameters include the original natural gas production under standard conditions. G i_gas Production of raw condensate oil under standard conditions G i_oil Cumulative natural gas production under standard conditions G p_gas Cumulative condensate production under standard conditions G p_oil Density of condensate oil relative to pure water γ oil The molecular weight of condensate oil relative to pure water M oil ; original formation pressure of the gas reservoir p i Original formation temperature of the gas reservoir T r and the natural gas deviation factor under the original formation pressure and temperature of the gas reservoir z i .

3. The calculation method according to claim 2, characterized in that, The relationship between the pseudo-pressure and the corresponding cumulative natural gas equivalent production for the period is as follows: （1） （2） （3） In the formula, p gas Formation pressure at different stages during gas reservoir development; z gas This refers to the natural gas deviation factor at different stages of gas reservoir development. p gas / z gas To simulate pressure; G i This represents the original formation natural gas equivalent reserves; G p To accumulate natural gas equivalent production.

4. The calculation method according to claim 3, characterized in that, The mixing gas deviation factor under the original formation pressure of CO2 injection into the gas reservoir is calculated by the following formula: （4） In the formula, z mix This is the deviation factor for the mixed gas under the original formation pressure of CO2 injection into the gas reservoir; z CO2 The CO2 deviation factor is the CO2 injection into the original formation pressure and temperature of the gas reservoir. R gas To determine the final recovery level of a gas reservoir, the equivalent reserves of natural gas in the original formation are used. G i and cumulative natural gas equivalent production G p The ratio is determined.

5. The calculation method according to claim 4, characterized in that, The effective CO2 sequestration capacity of the depleted gas reservoir is calculated using the following formula: （6） In the formula, Effective CO2 sequestration capacity of depleted gas reservoirs; This represents the CO2 density under standard conditions.

6. A calculation apparatus for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir using the calculation method described in any one of claims 1 to 5, characterized in that, include: The first processing unit is used to collect the original geological reserves of the target gas reservoir, production dynamic data, original formation pressure and temperature of the gas reservoir, high pressure physical property analysis and constant volume exhaustion test data, and to determine the calculation parameters. The second processing unit is used to obtain the formation pressure at different stages of the gas reservoir production process using production dynamic data, and to obtain the corresponding natural gas deviation factor by using the relationship between the deviation factor and pressure established by the constant volume depletion test data. It also establishes the relationship between the pseudo pressure and the cumulative natural gas equivalent production at the corresponding period, and then draws the cross-plot of the material balance relationship of the target gas reservoir production stage. If the cumulative natural gas equivalent production when the pseudo pressure is equal to 0 is consistent with the original formation natural gas reserves, then the influence of water intrusion is excluded, and the gas reservoir is determined to be a constant volume depletion gas reservoir. The third processing unit is used to query the CO2 deviation factor at the original formation pressure and temperature of CO2 injection into the gas reservoir, and to calculate the mixed gas deviation factor at the original formation pressure of CO2 injection into the gas reservoir using the final recovery degree of the gas reservoir. The fourth processing unit is used to calculate the injectable amount of CO2 into a depleted gas reservoir up to the original formation pressure using accumulated natural gas equivalent production, original formation natural gas reserves, and the mixing gas deviation factor under CO2 injection to the original formation pressure of the gas reservoir. The fifth processing unit is used to calculate the effective CO2 storage capacity of a depleted gas reservoir based on the injectable amount of CO2 injected into the reservoir's original formation pressure.

7. A computer-readable storage medium, characterized in that, The device contains a computer program that is executed by a processor to control the device where the processor is located to implement the steps of the method for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir as described in any one of claims 1 to 5.

8. A computer device, characterized in that, The method includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the method for calculating the effective carbon dioxide sequestration capacity of a fixed-volume depleted gas reservoir as described in any one of claims 1 to 5.

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