Numerical simulation method for CO2 storage and oil displacement development effect evaluation

Abstract

The invention relates to the technical field of oil exploration and development, and particularly provides a numerical simulation method for CO2 storage and oil displacement development effect evaluation. The method comprises the following steps: constructing a flow state physical model after CO2 enters a reservoir; according to the flow state physical model, a seepage model of CO2 entering the reservoir is established by combining the Darcy seepage theory and the mass conservation theory, and an oil phase formula, a water phase formula and a CO2 gas phase formula are obtained in a radial one-dimensional cylindrical coordinate system; dividing a calculation area into differential grids according to an oil phase formula, a water phase formula and a CO2 gas phase formula to obtain a limited number of grid nodes, and replacing a continuous solution domain with the limited number of grid nodes; according to the solution domain, calculating to obtain a relation expression of CO2 saturation changing along with radius and time; a prediction model is formed through the change relational expression, the CO2 storage or oil displacement state is predicted, the CO2 storage and oil displacement process is accurately simulated, and the CO2 emission reduction effect and potential can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of CO2 storage and oil recovery, and in particular to a numerical simulation method for evaluating the effects of CO2 storage and oil recovery development. Background Art

[0002] Carbon capture, utilization and storage (CCUS) technology is one of the key technologies for reducing CO2 emissions and mitigating the greenhouse effect. Compared with CO2 energy conservation and emission reduction, CCUS technology has a huge effect and potential for reducing CO2 emissions as long as the storage method and storage location are properly selected. Up to now, there are more than 200 CUSS projects in the world. Among them, CO2 flooding technology injects CO2 as a new displacement agent into the reservoir through injection wells to improve the properties of crude oil and reservoir porosity. On the one hand, it significantly improves the oil field recovery rate, and at the same time achieves CO2 emission reduction and storage, achieving a win-win situation. Numerical simulation of CO2 flooding is one of the key technologies in the development of oil and gas fields.

[0003] At present, most reservoir numerical simulation software on the market can simulate the CO2 displacement process, but in the entire simulation process it is impossible to accurately consider the impact of CO2 as one of the hydrocarbon components existing in both oil and gas phases on the overall fluidity of crude oil, as well as the impact of CO2 dissolution in water, chemical reactions between carbonic acid and formation minerals, and mineralization processes on reservoir permeability. Summary of the invention

[0004] In view of this, the present invention provides a numerical simulation method for evaluating the effects of CO2 storage and oil recovery development, so as to accurately simulate the processes of CO2 storage and oil recovery and effectively improve the effect and potential of CO2 emission reduction.

[0005] In a first aspect, the present invention provides a numerical simulation method for evaluating the effect of CO2 storage and oil recovery development, the method comprising: Step 1: construct a physical model of the flow state of CO2 after it enters the reservoir; Step 2: Based on the flow state physical model, combined with Darcy's seepage theory and mass conservation theory, a seepage model of CO2 entering the reservoir is established. In the radial one-dimensional cylindrical coordinate system, the mass continuity equation is used to calculate the water phase, oil phase and CO2 liquid phase respectively to obtain the oil phase formula, water phase formula and CO2 gas phase formula; Step 3: According to the oil phase formula, the water phase formula and the CO2 gas phase formula, the calculation area is divided into differential grids to obtain a finite number of grid nodes, and the finite number of grid nodes are used to replace the continuous solution domain; Step 4: According to the solution domain, calculate and obtain the relationship between CO2 saturation, radius and time; Step 5: Form a prediction model by changing the relationship to predict the CO2 storage or oil recovery status.

[0006] Optionally, the step 2 includes: At the center of the unit body, point O, along the direction of reservoir flow, the seepage velocity of free gas under standard conditions is , the seepage velocity of gas dissolved in oil and water under standard conditions is , ,in , is the dissolved gas-oil ratio, dissolved gas-water ratio; Under standard conditions, CO2 gas phase In time along x The difference in the gas mass flowing into and out of the unit cell in the direction is expressed as: ; exist The mass increment of the standard volume gas in the unit body within a certain time period is expressed as: ; The mass conservation equation of the gas component is expressed as: ; That is: ; During the oil displacement process, the three-phase fluid of oil, gas and water flows in the porous medium, and the flow obeys Darcy's law. The equation form of Darcy's law in the Cartesian coordinate system is: ; Substituting into the mass conservation equation of the gas component, the CO2 gas phase expression can be obtained as follows: ; (1) Similarly, the oil phase expression can be obtained as follows: ; (2) The aqueous phase expression is: (3).

[0007] Optionally, the step 3 includes: Assuming that capillary forces are neglected, , and order , , ; Substituting the above into the oil phase formula, water phase formula and CO2 gas phase formula, we can get: ; make , , , where the density , gas solubility , porosity are all functions of pressure P. , , The derivatives in are expanded according to time, and we can get: ; ; There are ,so We can get: ; Available through To eliminate , Then there is only one unknown quantity in the formula that needs to be solved : ; in, ; ; ; ; ; ; ; ; Then the oil phase formula, water phase formula and CO2 gas phase formula can be multiplied by the corresponding coefficients on the left and added to obtain: ; (7) No. The gas phase of unit number, the mass of gas passing through cylinder j is: ; The mass of gas passing through cylinder j-1 is: ; The gas mass increment of unit j is: ; The volume of unit j is: ; Then for the above formula (7), we can get: ; The proof is as follows: ; Similarly, we can get: ; (8) ; (9) ; (10) Then formula (7) is discretized for time t, from arrive In the time; for the radius r discretization, from arrive ;get: ; have to: ; have to: ; Logarithmic transformation in the radial direction Then discretize it, and get: ; After finishing, we can get: ; (11) For the total grid divided, the pressure of the N-1th unit is calculated, and the pressure of the Nth unit adopts the formation pressure.

[0008] Optionally, step 4 includes: According to the solution domain, the time t is discretized, from arrive In time, we get: ; ; ; After finishing, we can get: ; ; ; make ; It is the slope of saturation changing with time, which is a function of saturation and complies with the upstream weight method; after each pressure is calculated, a small step of MT is used. To calculate the saturation [S], the adaptive time step method .

[0009] In a second aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium includes a stored program, wherein when the program is run, the device where the computer-readable storage medium is located is controlled to execute the numerical simulation method for evaluating the effects of CO2 storage and oil recovery development in the first aspect or any possible implementation of the first aspect.

[0010] In a fourth aspect, an embodiment of the present invention provides an electronic device, comprising: one or more processors; a memory; and one or more computer programs, wherein the one or more computer programs are stored in the memory, and the one or more computer programs include instructions, which, when executed by the device, enable the device to execute the numerical simulation method for evaluating the effects of CO2 storage and oil recovery development in the first aspect or any possible implementation of the first aspect.

[0011] In the technical solution provided by the present invention, the method comprises constructing a physical model of the flow state after CO2 enters the reservoir; according to the physical model of the flow state, in combination with Darcy's seepage theory and mass conservation theory, a seepage model of CO2 entering the reservoir is established, and in a radial one-dimensional cylindrical coordinate system, the mass continuity equation is used to perform constant calculations on the water phase, the oil phase and the CO2 liquid phase respectively to obtain the oil phase formula, the water phase formula and the CO2 gas phase formula; according to the oil phase formula, the water phase formula and the CO2 gas phase formula, the calculation area is divided into differential grids to obtain a finite number of grid nodes, and the finite number of the grid nodes are used to replace the continuous solution domain; according to the solution domain, the relationship between the change of CO2 saturation with radius and time is calculated; a prediction model is formed by the change relationship to predict the CO2 storage or oil recovery state. The method accurately simulates the process of CO2 storage and oil recovery, and can effectively improve the effect and potential of CO2 emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 A flowchart of a numerical simulation method provided by an embodiment of the present invention; Figure 2 A schematic diagram of a unit body provided by an embodiment of the present invention; Figure 3 A schematic diagram of grid and unit division and numbering provided in an embodiment of the present invention; Figure 4 A graph showing water saturation at different times during a CO2 flooding simulation provided by an embodiment of the present invention; Figure 5 A graph showing the oil saturation at different times during the CO2 flooding simulation provided by an embodiment of the present invention; Figure 6 A graph showing the CO2 saturation at different times during the CO2 flooding simulation provided by an embodiment of the present invention; Figure 7A graph showing the change of water saturation over time at different radii during CO2 flooding simulation provided in an embodiment of the present invention; Figure 8 A graph showing the change of oil saturation over time at different radii during CO2 flooding simulation provided in an embodiment of the present invention; Fig. 9 A graph showing the change of CO2 saturation over time at different radii during CO2 flooding simulation provided in an embodiment of the present invention; Fig.10 A graph showing water saturation at different pressure differences during CO2 flooding simulation provided by an embodiment of the present invention; Fig.11 A graph showing oil saturation at different pressure differences during CO2 flooding simulation provided by an embodiment of the present invention; Fig.12 A graph showing CO2 saturation at different pressure differences during CO2 flooding simulation provided in an embodiment of the present invention; Fig.13 A graph showing water saturation at different porosities during CO2 flooding simulation provided by an embodiment of the present invention; Fig.14 A graph showing oil saturation at different porosities during CO2 flooding simulation provided in an embodiment of the present invention; Fig.15 A graph showing CO2 saturation at different porosities during CO2 flooding simulation provided in an embodiment of the present invention; Fig.16 A schematic diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] It should be clear that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention are also intended to include plural forms, unless the context clearly indicates other meanings.

[0017] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0018] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0019] Since the Sacroc oil field in the United States first adopted CO2 flooding in 1972, foreign petroleum engineers have conducted a lot of research on the mathematical model of CO2 flooding and proposed many different mathematical models of CO2 flooding. Shih-Hsien Chang et al. (1996) considered using foam displacement to simulate the CO2 displacement process. Durlofsky LJ et al. (2005)'s fluid flow model in a complex multiphase and multicomponent system described the miscible gas injection process by making a detailed calculation of the reservoir heterogeneity, indicating that miscible injection can improve the recovery rate and CO2 storage efficiency. Grogan et al. (2010) measured the diffusion coefficient of CO2 in hydrocarbons through a diffusion experiment, and established a mathematical model of the diffusion coefficient of CO2 in hydrocarbons at normal temperature and pressure. In terms of theoretical research on oil recovery, domestic scholars have carried out a lot of research. Cheng Linsong et al. (1998) established a three-dimensional reservoir numerical simulation model of oil, gas and water based on the solubility of CO2 in water. Hou Jian (2004) established a practical mathematical model of CO2 miscible flooding based on the improved black oil model. The mathematical model uses the adjustment of the relative permeability and effective viscosity of oil and gas to simulate the miscible process. Xu Geyuan et al. (2011) established a multi-phase and multi-component partitioned seepage model of CO2 flooding considering diffusion. Gao Ran et al. (2021) coupled the flash evaporation of oil and gas, the dissolution and corrosion of CO2 in water, and simultaneously simulated the distribution of CO2 in the three phases of oil, gas and water, the influence of dissolved CO2 on reservoir properties, and the whole process of CO2 flooding and storage.

[0020] In order to better understand the mechanism and influencing factors of CO2 flooding, optimize the flooding scheme, improve the recovery rate, reduce costs, and extend the life of the oil field, it is a very meaningful work to study the mathematical models involved in the numerical simulation of CO2 flooding. The increase in crude oil fluidity caused by the dissolution of CO2, the geophysical and chemical reactions in the formation under special conditions and the CO2 displacement process must be integrated to better simulate the CO2 flooding process. The present invention establishes a three-dimensional mathematical model of columnar formations, and solves and analyzes it based on this. It can simultaneously simulate the distribution of CO2 in the oil and gas phases, the dissolution of CO2 in water, and the reaction under special formation conditions during the displacement process. After further programming, the numerical simulation results are processed to optimize various parameters.

[0021] Figure 1 A flowchart of a numerical simulation method provided by an embodiment of the present invention, such as Figure 1 As shown, the method includes: Step 1: Construct a physical model of the flow state of CO2 after it enters the reservoir.

[0022] In the embodiment of the present invention, the flow state is the seepage driven by the pressure difference between the wellbore and the formation. Physical model of flow state: 1. Conforms to Darcy's seepage law; 2. Isothermal seepage; 3. Oil, gas and water three phases and oil, gas and water three components, the water component exists in the water phase, the oil component exists in the oil phase, and the oil and water phases are immiscible; the gas component not only exists in the gas phase, but also dissolves in the oil phase and the water phase; 4. One-dimensional flow; 5. Both rock and fluid are compressible; 6. The reservoir is heterogeneous and anisotropic; 7. Capillary force and gravity are not considered.

[0023] Step 2: Based on the physical model of the flow state, combined with Darcy's seepage theory and mass conservation theory, a seepage model of CO2 entering the reservoir is established. In the radial one-dimensional cylindrical coordinate system, the mass continuity equation is used to calculate the water phase, oil phase and CO2 liquid phase respectively to obtain the oil phase formula, water phase formula and CO2 gas phase formula.

[0024] In the embodiment of the present invention, Figure 2 As shown, step 2 includes: At the center of the unit body, point O, along the direction of reservoir flow, the seepage velocity of free gas under standard conditions is , the seepage velocity of gas dissolved in oil and water under standard conditions is , ,in , is the dissolved gas-oil ratio, dissolved gas-water ratio; Under standard conditions, CO2 gas phase In time along x The difference in the gas mass flowing into and out of the unit cell in the direction is expressed as: ; exist The mass increment of the standard volume gas in the unit body within a certain time period is expressed as: ; The mass conservation equation of the gas component is expressed as: ; That is: ; During the oil displacement process, the three-phase fluid of oil, gas and water flows in the porous medium, and the flow obeys Darcy's law. The equation form of Darcy's law in the Cartesian coordinate system is: ; Substituting into the mass conservation equation of the gas component, the CO2 gas phase expression can be obtained as follows: ; (1) Similarly, the oil phase expression can be obtained as follows: ; (2) The aqueous phase expression is: (3).

[0025] Step 3: According to the oil phase formula, the water phase formula and the CO2 gas phase formula, the calculation area is divided into differential grids to obtain a finite number of grid nodes, and the finite number of grid nodes are used to replace the continuous solution domain.

[0026] In the embodiment of the present invention, step 3 includes: Assuming that capillary forces are neglected, , and order , , ; Substituting the above into the oil phase formula, water phase formula and CO2 gas phase formula, we can get: ; make , , , where the density , gas solubility , porosity are all functions of pressure P. , , The derivatives in are expanded according to time, and we can get: ; ; There are ,so We can get: ; Available through To eliminate , Then there is only one unknown quantity in the formula that needs to be solved : ; in, ; ; ; ; ; ; ; ; Then the oil phase formula, water phase formula and CO2 gas phase formula can be multiplied by the corresponding coefficients on the left and added to obtain: ; (7) No. The gas phase of unit number, the mass of gas passing through cylinder j is: ; The mass of gas passing through cylinder j-1 is: ; The gas mass increment of unit j is: ; The volume of unit j is: ; Then for the above formula (7), we can get: ; The proof is as follows: ; Similarly, we can get: ; (8) ; (9) ; (10) Then formula (7) is discretized for time t, from arrive In the time; for the radius r discretization, from arrive ;get: ; have to: ; have to: ; Logarithmic transformation in the radial direction Then discretize it, and get: ; After finishing, we can get: ; (11) For the total grid divided, the pressure of the N-1th unit is calculated, and the pressure of the Nth unit adopts the formation pressure.

[0027] In the embodiment of the present invention, a finite number of grid nodes replaces a continuous solution domain to construct a matrix for solving pressure by using the obtained equation for solving pressure, such as Figure 3 The grid and unit division and numbering shown are explanations for the construction of parameters in the matrix equation. The upstream weight method is used to determine the value of the relative permeability, so that the pressure at time n can be solved by the pressure at time n-1.

[0028] The general formula for pressure solution is derived from the oil phase formula, water phase formula and CO2 gas phase formula to obtain the pressure solution equation for each unit. The pressure solution equations of all units are combined to form a pressure solution matrix, thereby solving the pressure of each unit. Unit division: Discretization on radial radius r , forming a unit sequence .

[0029] Step 4: Based on the solution domain, calculate and obtain the relationship between CO2 saturation, radius and time.

[0030] In the embodiment of the present invention, step 4 includes: According to the solution domain, substitute formulas (8), (9), and (10) into formulas (4), (5), and (6), and discretize time t, from arrive In time, we get: ; ; ; After finishing, we can get: ; ; ; make ; It is the slope of saturation changing with time, which is a function of saturation and complies with the upstream weight method; after each pressure is calculated, a small step of MT is used. To calculate the saturation [S], the adaptive time step method .

[0031] Step 5: Form a prediction model by changing the relationship to predict the CO2 storage or oil recovery status.

[0032] Combining theoretical algorithms, writing programs, and forming a prediction model, the simulation process includes: Set the formation model parameters, such as setting the layer height grid division, simulation time, etc.; set initial conditions, such as pressure, initial saturation, porosity, etc.; calculate the relative permeability of the three phases of oil, gas and water; solve the pressure P implicitly through the matrix; correct the porosity according to the geophysical and chemical reactions, and apply viscosity correction; solve the saturation of the three phases of oil, gas and water; calculate the time step, and determine the simulation time, and complete the simulation based on the judgment result.

[0033] In the embodiment of the present invention, Figures 4 to 6 As shown in the figure, the horizontal axis is the displacement radius of the formation, and the vertical axis is the saturation of the three phases of water, oil, and CO2 gas; the curves in the figure represent the water saturation under different invasion days. It can be clearly seen from the curves in the figure that: with the continuous progress of immiscible displacement, the displacement radius increases with the increase of displacement time, but the growth rate of the displacement radius of the formation decreases with the increase of displacement time, the time taken for the water phase saturation to increase from the bound water saturation to the initial water saturation of the formation is getting longer and longer, and the saturation increase rate is getting smaller and smaller; the time taken for the oil phase saturation to increase from the residual oil saturation to the saturation peak and then decrease to the initial oil saturation of the formation is getting longer and longer, and the saturation increase rate is getting smaller and smaller, and the ring effect of the displacement is becoming more and more obvious; the time taken for the CO2 gas phase saturation to decrease from the retained CO2 gas saturation to the initial CO2 gas saturation of the formation is getting longer and longer, and the saturation increase rate is getting smaller and smaller. CO2 gas drives the movable water and movable oil in the formation away from the central wellbore, and only bound water, residual oil and CO2 gas remain in the pores of the affected units, that is, the part parallel to the horizontal axis at the front end of each curve, and the part parallel to the horizontal axis at the back end of each curve is the formation that has not been affected by CO2 displacement, and the three-phase saturation of water, oil and CO2 gas still maintains the initial value.

[0034] In the embodiment of the present invention, Figures 7 to 9As shown in the figure, the horizontal axis is the invasion time, and the vertical axis is the three-phase saturation of water, oil, and CO2 gas. It can be clearly seen from the curves in the figure that the three-phase saturations of water, oil, and CO2 gas in units at different positions in the formation begin to change at different times, and the rates of change are also different. As the immiscible displacement process proceeds, in the first 10 days of this oil displacement simulation, the time taken for the water phase saturation of the unit close to the wellbore to decrease from the initial saturation of the formation to the bound water saturation is shorter, and the saturation decrease rate is faster; the time taken for the unit far away from the wellbore is longer, and the decrease rate is smaller. The time taken for the oil phase saturation of the unit close to the wellbore to increase from the initial saturation of the formation to the peak value of the formation oil saturation and then decrease to the residual oil saturation is shorter, and the saturation change rate is faster; the time taken for the unit far away from the wellbore is longer, and the decrease rate is smaller. As CO2 gas displaces the formation fluid away from the wellbore, the CO2 gas saturation begins to increase from zero. As the immiscible displacement proceeds, the CO2 gas saturation in the unit increases until the pores in the formation are filled with CO2 gas except for residual oil and bound water. As the unit radius increases, the unit volume becomes larger, resulting in a longer immiscible displacement time. At the same time, compared with the water phase saturation, at the same position in the formation, the time it takes for the oil phase saturation to decrease to the residual oil saturation is longer than the time it takes for the water phase to decrease to the bound water saturation.

[0035] In the embodiment of the present invention, Figures 10 to 12 As shown, the horizontal axis is the displacement radius of the formation, and the vertical axis is the saturation of the three phases of water, oil, and CO2 gas; the difference between the bottom hole pressure and the original formation pressure is 1Mpa, 2.5Mpa, 5Mpa, 7.5Mpa, and 10Mpa, respectively. It can be clearly seen from the simulation results that within the same simulation time, the greater the pressure difference between the wellbore and the formation, the larger the radius of CO2 displacement and the more obvious the invasion ring. This is because the pressure difference between the wellbore and the formation drives the water and oil two-phase fluids to seep into the formation pores. When the formation pressure is fixed, the greater the bottom hole pressure, the greater the CO2 displacement rate and the larger the displacement radius.

[0036] In the embodiment of the present invention, Figures 13 to 15 As shown in the figure, the horizontal axis is the displacement radius of the formation, and the vertical axis is the saturation of the three phases of water, oil, and CO2 gas. The porosity of the formation is 0.1, 0.15, 0.2, 0.25, and 0.3 respectively. It can be clearly seen from the saturation curve of the three phases that within the same simulation time, the greater the porosity of the formation, the smaller the radius of CO2 displacement, and the narrower the annulus of the oil phase. The larger the pores in the formation, the larger the volume to be displaced, and the lower the efficiency of the displacement.

[0037] Each step of the embodiment of the present invention may be performed by an electronic device, which includes but is not limited to a mobile phone, a tablet computer, a portable PC, a desktop computer, etc.

[0038] In the technical solution provided by the present invention, the method comprises constructing a physical model of the flow state after CO2 enters the reservoir; according to the physical model of the flow state, in combination with Darcy's seepage theory and mass conservation theory, a seepage model of CO2 entering the reservoir is established, and in a radial one-dimensional cylindrical coordinate system, the mass continuity equation is used to perform constant calculations on the water phase, the oil phase and the CO2 liquid phase respectively to obtain the oil phase formula, the water phase formula and the CO2 gas phase formula; according to the oil phase formula, the water phase formula and the CO2 gas phase formula, the calculation area is divided into differential grids to obtain a finite number of grid nodes, and the finite number of the grid nodes are used to replace the continuous solution domain; according to the solution domain, the relationship between the change of CO2 saturation with radius and time is calculated; a prediction model is formed by the change relationship to predict the CO2 storage or oil recovery state. The method accurately simulates the process of CO2 storage and oil recovery, and can effectively improve the effect and potential of CO2 emission reduction.

[0039] An embodiment of the present invention provides a computer-readable storage medium, which includes a stored program, wherein when the program is running, the electronic device where the computer-readable storage medium is located is controlled to execute the above-mentioned embodiment of the numerical simulation method for evaluating the effect of CO2 storage and oil recovery development.

[0040] Fig.16 A schematic diagram of an electronic device provided by an embodiment of the present invention, such as Fig.16 As shown, the electronic device 21 includes: a processor 211, a memory 212, and a computer program 213 stored in the memory 212 and executable on the processor 211. When the computer program 213 is executed by the processor 211, the numerical simulation method for evaluating the effect of CO2 storage and oil recovery development in the embodiment is implemented. To avoid repetition, they are not described one by one here.

[0041] The electronic device 21 includes, but is not limited to, a processor 211 and a memory 212. Those skilled in the art will appreciate that Fig.16 It is only an example of the electronic device 21 and does not constitute a limitation of the electronic device 21. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device may also include input and output devices, network access devices, buses, etc.

[0042] The processor 211 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0043] The memory 212 may be an internal storage unit of the electronic device 21, such as a hard disk or memory of the electronic device 21. The memory 212 may also be an external storage device of the electronic device 21, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card (FlashCard), etc. equipped on the electronic device 21. Further, the memory 212 may also include both an internal storage unit of the electronic device 21 and an external storage device. The memory 212 is used to store computer programs and other programs and data required by network devices. The memory 212 may also be used to temporarily store data that has been output or is to be output.

[0044] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A numerical simulation method for evaluating the effect of CO2 storage and oil recovery development, characterized in that: The method comprises: Step 1: construct a physical model of the flow state of CO2 after it enters the reservoir; Step 2: Based on the flow state physical model, combined with Darcy's seepage theory and mass conservation theory, a seepage model of CO2 entering the reservoir is established. In the radial one-dimensional cylindrical coordinate system, the mass continuity equation is used to calculate the water phase, oil phase and CO2 liquid phase respectively to obtain the oil phase formula, water phase formula and CO2 gas phase formula; Step 3: According to the oil phase formula, the water phase formula and the CO2 gas phase formula, the calculation area is divided into differential grids to obtain a finite number of grid nodes, and the finite number of grid nodes are used to replace the continuous solution domain; Step 4: According to the solution domain, calculate and obtain the relationship between CO2 saturation, radius and time; Step 5: Form a prediction model by changing the relationship to predict the CO2 storage or oil recovery status.

2. The method according to claim 1, characterized in that The step 2 comprises: At the center of the unit body, point O, along the direction of reservoir flow, the seepage velocity of free gas under standard conditions is , the seepage velocity of gas dissolved in oil and water under standard conditions is , ,in , is the dissolved gas-oil ratio, dissolved gas-water ratio; Under standard conditions, CO2 gas phase In time along x The difference in the gas mass flowing into and out of the unit cell in the direction is expressed as: ； exist The mass increment of the standard volume gas in the unit body within a certain time period is expressed as: ； The mass conservation equation of the gas component is expressed as: ； That is: ； During the oil displacement process, the three-phase fluid of oil, gas and water flows in the porous medium, and the flow obeys Darcy's law. The equation form of Darcy's law in the Cartesian coordinate system is: ； Substituting into the mass conservation equation of the gas component, the CO2 gas phase expression can be obtained as follows: ；（1） Similarly, the oil phase expression can be obtained as follows: ；（2） The aqueous phase expression is: （3）。 3. The method according to claim 1, characterized in that The step 3 comprises: Assuming that capillary forces are neglected, , and order , , ; Substituting the above into the oil phase formula, water phase formula and CO2 gas phase formula, we can get: ； make , , , where the density , gas solubility , porosity are all functions of pressure P. , , The derivatives in are expanded according to time, and we can get: ； ； ； There are ,so We can get: ； Available through To eliminate , Then there is only one unknown quantity in the formula that needs to be solved : ； in, ； ； ； ； ； ； ； ； Then the oil phase formula, water phase formula and CO2 gas phase formula can be multiplied by the corresponding coefficients on the left and added to obtain: ；（7） No. The gas phase of unit number, the mass of gas passing through cylinder j is: ； The mass of gas passing through cylinder j-1 is: ； The gas mass increment of unit j is: ； The volume of unit j is: ； Then for the above formula (7), we can get: ； The proof is as follows: ； Similarly, we can get: ; (8) ；（9） ；（10） Then formula (7) is discretized for time t, from arrive In the time; for the radius r discretization, from arrive ;get: ； have to: ； have to: ； Logarithmic transformation in the radial direction Then discretize it, and get: ； After finishing, we can get: ；（11） For the total grid divided, the pressure of the N-1th unit is calculated, and the pressure of the Nth unit adopts the formation pressure.

4. The method according to claim 1, characterized in that: The step 4 comprises: According to the solution domain, the time t is discretized, from arrive In time, we get: ； ； ； After finishing, we can get: ； ； ； make ； It is the slope of saturation changing with time, which is a function of saturation and complies with the upstream weight method; after each pressure is calculated, a small step of MT is used. To calculate the saturation [S], the adaptive time step method .

5. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the numerical simulation method for evaluating the effect of CO2 storage and oil recovery development as described in any one of claims 1 to 4.

6. An electronic device, characterized in that: include: one or more processors; Memory; And one or more computer programs, wherein the one or more computer programs are stored in the memory, and the one or more computer programs include instructions, which, when executed by the device, enable the device to execute the numerical simulation method for evaluating the effect of CO2 storage and oil recovery development as described in any one of claims 1 to 4.

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