A numerical simulation technology system for carbon dioxide flooding and storage

Abstract

The present application discloses a numerical simulation technology system for carbon dioxide pressure-driven oil displacement and storage, which relates to the field of CCUS numerical simulation. The technology system includes: a geological data acquisition module for acquiring geological data of the target oilfield site; a reservoir geological model construction module for constructing a reservoir geological model for the CO2 pressure-driven process in the deep shale reservoir based on the geological data; a mathematical model establishment module for carbon dioxide pressure-driven oil displacement and storage, which establishes a mathematical model for carbon dioxide pressure-driven oil displacement and storage in the deep shale reservoir based on the multiphase and multicomponent seepage model and the mechanical deformation model, and combines the constitutive model of reservoir damage mechanics; a numerical simulation module for carbon dioxide pressure-driven oil displacement and storage, which solves the seepage equation and the mechanical equation, and performs iterative coupling solution of the fluid-solid two fields based on the fixed stress decomposition algorithm to conduct numerical simulation of carbon dioxide pressure-driven oil displacement and storage in the deep shale reservoir, and can better simulate the changes in porosity, permeability and the evolution of the damage area during the process of carbon dioxide pressure-driven oil displacement and storage.

Description

Technical Field

[0001] This application relates to the field of CCUS numerical simulation, and particularly to a numerical simulation technology system for carbon dioxide pressure drive oil displacement and storage. Background Art

[0002] In the oil reservoirs discovered or developed in recent years, the proportion of deep shale oil reservoirs has gradually increased, and their oil and gas reserves are huge, making them an important front for increasing reserves and production. However, such reservoirs have the characteristics of poor physical properties, low conductivity, and small natural energy, making them difficult to exploit. Generally, fracturing production is required. Although fracturing technology can efficiently increase the production of a single well, the drilling cost is too high, the production decline is fast, unsustainable exploitation, and the difficulty of replenishing the energy of the reservoir in the later stage are the disadvantages of this fracturing method. Therefore, the pressure drive process has been developed. By using large-displacement, high-pressure pumping equipment, pumping a large amount of displacing agent into the formation continuously in a short period at a pumping pressure higher than the formation fracture pressure to supplement the formation energy, improve the oil well productivity and oil displacement efficiency, thereby improving the development effect of the well group.

[0003] Existing research mainly focuses on pressure drive water injection development, and there is little research on the CO 2 pressure drive exploitation of deep shale oil reservoirs. Therefore, aiming at the problems of unclear understanding of the mechanism in the pressure drive process and lack of corresponding numerical simulation technology, there is an urgent need for a numerical simulation technology system for CO 2 pressure drive oil displacement and storage in deep shale oil reservoirs. Summary of the Invention

[0004] The purpose of this application is to provide a numerical simulation technology system for carbon dioxide pressure drive oil displacement and storage, which can simulate the changes in porosity, permeability, and the evolution of the damaged area during the CO 2 pressure drive oil displacement and storage process.

[0005] To achieve the above purpose, this application provides the following solutions:

[0006] This application provides a numerical simulation technology system for carbon dioxide pressure drive oil displacement and storage, including the following modules:

[0007] A geological data acquisition module, used for: acquiring the geological data of the target oilfield site;

[0008] An oil reservoir geological model construction module, used for: constructing an oil reservoir geological model for the deep shale oil reservoir CO 2 pressure drive process according to the geological data;

[0009] A pressure drive oil displacement and storage mathematical model establishment module, used for: establishing a mathematical model for carbon dioxide pressure drive oil displacement and storage in deep shale oil reservoirs based on the multiphase multicomponent seepage model and the mechanical deformation model, and combining the constitutive model of reservoir damage mechanics; the mathematical model for carbon dioxide pressure drive oil displacement and storage in the deep shale oil reservoir 2 ; 2The mathematical model of pressure-driven oil displacement and storage includes multiphase and multicomponent fluid seepage equations, stress equilibrium equations, effective stress equations, dynamic change relationship equations of matrix porosity, and dynamic change relationship equations of permeability.

[0010] The numerical simulation module for pressure-driven oil displacement and storage is used for: solving the seepage equation and mechanical equation, iteratively coupling and solving the fluid-solid two fields based on the fixed stress decomposition algorithm, and carrying out CO2 2 pressure-driven oil displacement and storage numerical simulation to obtain numerical simulation results.

[0011] Optionally, the geological data includes reservoir parameters, fluid physical property parameters, and CO2 2 injection parameters.

[0012] Optionally, the reservoir geological model construction module specifically includes: based on the geological data, constructing a deep shale oil reservoir CO2 2 reservoir geological model for the pressure-driven process.

[0013] Optionally, the constitutive model of reservoir damage mechanics is expressed as follows:

[0014] ;

[0015] Where is the effective stress tensor of the rock, is the stress tensor, is the identity matrix, is the rock damage factor, is the elastic tensor, is the strain tensor.

[0016] Optionally, the numerical simulation technology system for carbon dioxide pressure-driven oil displacement and storage further includes a rock damage factor determination module, and the rock damage factor determination module is used for: determining the rock damage factor according to the reservoir tensile damage factor and the reservoir shear damage factor; the reservoir tensile damage factor and the reservoir shear damage factor are expressed as follows:

[0017] ;

[0018] ;

[0019] Where is the reservoir tensile damage factor, is the maximum principal stress, is the uniaxial tensile strength of the rock, is the reservoir shear damage factor, is the minimum principal stress, is the internal friction angle, is the uniaxial compressive strength of the rock.

[0020] Optionally, the rock damage factor determination module specifically includes:

[0021] When the reservoir tensile damage factor is greater than or equal to 0, the relationship between the rock damage factor and the strain tensor is as follows:

[0022] ;

[0023] When the reservoir shear damage factor is greater than or equal to 0, the relationship between the rock damage factor and the strain tensor is as follows:

[0024] ;

[0025] Wherein, is the ratio of the change in tensile strength, , is the residual tensile strength of the rock, is the initial uniaxial tensile strength of the rock, is the tensile damage strain threshold, is the ultimate tensile strain, is the shear damage strain threshold.

[0026] Optionally, the pressure-driven oil displacement and storage numerical simulation module specifically includes:

[0027] Step 501: In each time step, fix the current in-situ stress field, and use the finite volume method to iteratively solve the seepage equation to obtain the fluid pressure field distribution, and update the matrix and fracture porosities in real time during the iteration process;

[0028] Step 502: Based on the fluid pressure field distribution, use the finite element method to iteratively solve the mechanical equation to obtain the in-situ stress field distribution, and update the matrix and fracture porosities and permeabilities;

[0029] Step 503: Based on the in-situ stress field distribution, determine whether each grid cell is damaged, and update the permeability of the damaged grid cells;

[0030] Step 504: Repeat Step 501 and Step 502 until the coupled iteration converges, and enter the next time step.

[0031] Optionally, the numerical simulation results include reservoir pressure, saturation, oil production, and water cut.

[0032] According to the specific embodiments provided by the present application, the following technical effects are disclosed in the present application:

[0033] The present application provides a numerical simulation technology system for carbon dioxide pressure-driven oil displacement and storage, obtains geological data of the target oilfield site, and constructs a deep shale oil reservoir CO 2Reservoir geological model for the pressure drive process; based on the multi-phase and multi-component seepage model and the mechanical deformation model, combined with the constitutive model of reservoir damage mechanics, a CO 2 Mathematical model for pressure drive oil displacement and storage; solve the seepage equation and the mechanical equation, and perform iterative coupling solution of the fluid-solid two fields based on the fixed stress decomposition algorithm to carry out CO 2 Numerical simulation of pressure drive oil displacement and storage, obtain the numerical simulation results, and establish a CO 2 Mathematical model for pressure drive oil displacement and storage in deep shale reservoirs, and carry out CO 2 Numerical simulation of pressure drive oil displacement and storage, which can better simulate CO 2 During the process of pressure drive oil displacement and storage, the changes in porosity, permeability and the evolution of the damage area, for CO 2 Provide technical support for the pressure drive development of deep shale reservoirs, which can be used to guide the efficient development of oilfields, improve the oilfield production effect and development benefit. Brief description of the drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 It is a schematic flow chart of a numerical simulation technology system for carbon dioxide pressure drive oil displacement and storage provided by an embodiment of the present application;

[0036] Figure 2 It is a schematic detailed flow chart of the numerical simulation of CO 2 Oil displacement and storage in deep shale reservoirs provided by an embodiment of the present application;

[0037] Figure 3 It is a schematic flow chart of the numerical calculation and solution of the fixed stress decomposition algorithm provided by an embodiment of the present application;

[0038] Figure 4 It is a schematic diagram of a low-permeability reservoir model and its calculation grid provided by an embodiment of the present application;

[0039] Figure 5 It is a schematic diagram of the matrix porosity distribution of a low-permeability reservoir provided by an embodiment of the present application;

[0040] Figure 6 It is a schematic diagram of the matrix permeability distribution of a low-permeability reservoir provided by an embodiment of the present application;

[0041] Figure 7Schematic diagram of pressure drive stress distribution provided by an embodiment of the present application;

[0042] Figure 8 Schematic diagram of the evolution of damage factor after pressure drive provided by an embodiment of the present application;

[0043] Figure 9 Schematic diagram of the comparison results between the simulated daily oil production and water cut of the production wells of Niu 6-x22 and Niu 21-x2 and the historical production data provided by an embodiment of the present application; Figure 9 In (a), it is the comparison result between the simulated daily oil production of the production well of Niu 6-x22 and the historical production data; Figure 9 In (b), it is the comparison result between the simulated water cut of the production well of Niu 6-x22 and the historical production data; Figure 9 In (c), it is the comparison result between the simulated daily oil production of the production well of Niu 21-x2 and the historical production data; Figure 9 In (d), it is the comparison result between the simulated water cut of the production well of Niu 21-x2 and the historical production data;

[0044] Figure 10 Schematic diagram of the comparison results between the simulated daily oil production and water cut of the production wells of Niu 21-x3 and Niu 21-x5 and the historical production data provided by an embodiment of the present application; Figure 10 In (a), it is the comparison result between the simulated daily oil production of the production well of Niu 21-x3 and the historical production data; Figure 10 In (b), it is the comparison result between the simulated water cut of the production well of Niu 21-x3 and the historical production data; Figure 10 In (c), it is the comparison result between the simulated daily oil production of the production well of Niu 21-x5 and the historical production data; Figure 10 In (d), it is the comparison result between the simulated water cut of the production well of Niu 21-x5 and the historical production data. Detailed implementation manners

[0045] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0046] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0047] In an exemplary embodiment, as Figure 1 and Figure 2As shown, a numerical simulation technology system for carbon dioxide pressure drive enhanced oil recovery and storage is provided, and the technology system includes the following modules.

[0048] Geological data acquisition module T1, for: acquiring geological data of the target oilfield site.

[0049] Reservoir geological model construction module T2, for: constructing a deep shale reservoir CO 2 Reservoir geological model during pressure drive process.

[0050] Pressure drive enhanced oil recovery and storage mathematical model establishment module T3, for: based on the multi-phase multi-component seepage model and the mechanical deformation model, and combined with the constitutive model of reservoir damage mechanics, establishing a deep shale reservoir CO 2 Pressure drive enhanced oil recovery and storage mathematical model; the deep shale reservoir CO 2 The pressure drive enhanced oil recovery and storage mathematical model includes multi-phase multi-component fluid seepage equations, stress balance equations, effective stress equations, dynamic change relationship equations of matrix porosity, and dynamic change relationship equations of permeability.

[0051] Pressure drive enhanced oil recovery and storage numerical simulation module T4, for: solving the seepage equation and the mechanical equation, iteratively coupling and solving the fluid-solid two fields based on the fixed stress decomposition algorithm, and performing numerical simulation of deep shale reservoir CO 2 Pressure drive enhanced oil recovery and storage numerical simulation to obtain numerical simulation results.

[0052] Based on the above modules T1 to T4, it is possible to better simulate the changes in porosity, permeability, and the evolution of the damage area during the CO 2 Pressure drive enhanced oil recovery and storage process, which can provide technical support for the formulation of pressure drive water injection plans in the oilfield site.

[0053] In another exemplary embodiment of the present application, the geological data includes reservoir parameters, fluid physical property parameters, and CO 2 Injection parameters.

[0054] The above reservoir geological model construction module T2 specifically includes: based on the geological data, constructing a deep shale reservoir CO 2 Reservoir geological model during pressure drive process. Specifically, the model of the target oilfield site is divided into multiple grid units, and geological data is loaded for each grid unit.

[0055] Based on the multi-phase multi-component seepage model and the mechanical deformation model, combined with the constitutive model of reservoir damage mechanics and the relationship between matrix and pore permeability changes, establishing a deep shale reservoir CO 2 Pressure drive enhanced oil recovery and storage mathematical model.

[0056] Using the phase equilibrium module to perform multi-phase multi-component fluid seepage simulation calculations, and the specific calculation process of the phase equilibrium module is as follows:

[0057] During the process of CO 2 pressure-driven oil displacement and storage in deep shale reservoirs, the coupling relationship between seepage and stress has a significant impact on the mechanical behavior characteristics and seepage characteristics of rocks. Considering the complex phase changes involved in the CO 2 pressure-driven oil displacement and storage development process in deep shale reservoirs, a multi-phase and multi-component model is used to describe the fluid seepage process. The mass conservation equations of each component in the system can be uniformly expressed in the form shown in Equation (1) below. The components include hydrocarbon components and water components. The multi-phase and multi-component fluid seepage equation is as follows.

[0058] (1);

[0059] (2);

[0060] In the formula, the subscripts o, g, and w represent the oil phase, gas phase, and water phase respectively; represent the oil phase density, gas phase density, and water phase density respectively, Component The mole fraction of the component in the oil phase, Component The mole fraction of the component in the gas phase, is the total number of components, is the saturation, is the porosity, is the time, is the source-sink term of each component caused by injection and production, is the seepage velocity, which obeys the Darcy's law of multi-phase flow and can be calculated by the following formula:

[0061] (3);

[0062] In the formula, = o, g, w, representing the oil phase, gas phase, or water phase respectively, is the absolute permeability, is the relative permeability; is the viscosity, is the fluid pressure, is the depth. In order to make the mass conservation equation solvable, the following constraint equations are also required, including the saturation relationship, component mole fraction relationship, and capillary force relationship, as follows:

[0063] (4);

[0064] (5);

[0065] (6);

[0066] In the formula, is the total mole fraction of component in the oil-gas two-phase, is the capillary force at the oil-water interface, is the capillary force at the oil-gas interface, are the oil-phase pressure, gas-phase pressure or water-phase pressure respectively. The fluid PVT relationships involved in the above equations can be given by the equation of state shown below:

[0067] (7);

[0068] In the formula, R is the gas constant, V is the fluid volume, T is the fluid temperature, a and b are constants.

[0069] The stress balance equation is shown as follows:

[0070] (8);

[0071] The effective stress equation is shown as follows:

[0072] (9);

[0073] The geometric equation is shown as follows:

[0074] (10);

[0075] In the formula, is the rock density, is the acceleration of gravity, is the stress tensor, is the elastic tensor, is the strain tensor, is the displacement, is the Biot coefficient, is the identity matrix, is the total fluid pressure.

[0076] The equations for the dynamic variation relationships of matrix porosity and permeability are shown as follows respectively.

[0077] (11);

[0078] (12);

[0079] In the formula, represents the matrix porosity, and the subscript 0 represents the initial value, represents the initial value of the matrix porosity, is the initial value of the total fluid pressure, is the drainage bulk modulus, is the volumetric strain, is the initial value of the volumetric strain, represents the matrix permeability, is the initial value of the matrix permeability.

[0080] Fracture mechanics deformation model: For fractures, the normal fracture closure is calculated by the following formula:

[0081] (13);

[0082] In the formula, is the normal fracture closure, is the maximum allowable normal closure of the fracture, is the normal stress applied to the fracture, is the normal fracture stiffness.

[0083] The constitutive model of reservoir damage mechanics is expressed as follows:

[0084] (14);

[0085] Among them, is the effective stress tensor of the rock, is the rock damage factor.

[0086] Among them, the carbon dioxide pressure drive oil displacement and storage numerical simulation technology system further includes a rock damage factor determination module, and the rock damage factor determination module is used to: determine the rock damage factor according to the reservoir tensile damage factor and the reservoir shear damage factor; the reservoir tensile damage factor and the reservoir shear damage factor are expressed as follows:

[0087] (15);

[0088] (16);

[0089] Among them, is the reservoir tensile damage factor, is the maximum principal stress, is the uniaxial tensile strength of the rock, is the reservoir shear damage factor, is the minimum principal stress, is the internal friction angle, is the uniaxial compressive strength of the rock.

[0090] Among them, the rock damage factor determination module specifically includes: according to the elastic-brittle damage judgment model, when the reservoir tensile damage factor is greater than or equal to 0, that is, when tensile damage occurs, the rock damage factor The relationship with the strain tensor is as follows:

[0091] (17);

[0092] When the reservoir shear damage factor is greater than or equal to 0, that is when, the rock undergoes shear damage, and the rock damage factor The relationship with the strain tensor is as follows:

[0093] (18);

[0094] Among them, is the ratio of the change in tensile strength, , is the residual tensile strength of the rock, is the initial uniaxial tensile strength of the rock, is the tensile damage strain threshold, is the ultimate tensile strain, is the shear damage strain threshold.

[0095] The evolution law of the absolute permeability based on the rock damage factor is as follows:

[0096] (19);

[0097] In the formula, is the damage permeability influence coefficient, is the initial permeability.

[0098] The fully implicit solution of the residual form of the seepage equation by the finite volume method:

[0099] (20);

[0100] (21);

[0101] Among them, represents the residual of the seepage equation of the grid cell n component at the +1 time step, represents the conductivity between the grid cell at the +1 time step and the grid cell n and the grid cell m , represents the flow potential of the oil phase in the grid cell m at the +1 time step, represents the flow potential of the oil phase in the grid cell n at the +1 time step, represents The flow potential of the gas phase in the m +1 time-step grid cell, is denoted as the flow potential of the gas phase in the n +1 time-step grid cell, denotes the grid cell n where the residual of the seepage equation of the aqueous phase at the +1 time-step, denotes the set of adjacent grid cells of the grid cell n .

[0102] It is solved iteratively using the Newton-Raphson method:

[0103] (22);

[0104] (23);

[0105] In the formula, p denotes the iteration step, denotes the time step, l denotes the main variable number (such as the oil-phase pressure , the aqueous-phase saturation and the total component mole fraction etc.), denotes the increment of the main variable at the p +1-th iteration step, +1 denotes the current time step, x and

[0106] is the main variable.

[0107] (24);

[0108] In the formula, denotes the residual vector of the mechanical equation, ; is the differential operator matrix, is the shape function matrix; is the delta Dirac function vector, and for a two-dimensional problem, it is defined as =[1, 1, 0] T ; for a three-dimensional problem, it is defined as =[1, 1, 1, 0, 0, 0] T , is the total area where the stress is applied, is the matrix boundary, is the fracture boundary, and

[0109] Solve iteratively using the Newton-Raphson method:

[0110] (25);

[0111] (26);

[0112] According to the above process, perform numerical simulation of CO 2 pressure-driven oil displacement and storage in deep shale reservoirs; perform reservoir numerical simulation through the above steps, output the numerical simulation results, and the numerical simulation results include reservoir pressure, saturation, oil production, and water cut, that is, obtain simulation results such as reservoir pressure, saturation, and oil and water production curves.

[0113] The following is a further detailed description of the numerical simulation of pressure-driven oil displacement and storage. Use the numerical simulation technology of CO 2 pressure-driven oil displacement and storage to carry out numerical simulation in XX block: The geometric shape of the model is as Figure 4 shown, the initial oil saturation is 0.8, the initial water saturation is 0.2, the viscosity of the oil is 0.33, and the matrix porosity and permeability distributions of the low-permeability reservoir are as Figure 5 and Figure 6 shown.

[0114] In the first step, obtain reservoir parameters, fluid physical property parameters, and CO 2 injection parameters, etc., and preprocess the parameters to form an input file;

[0115] In the second step, perform calculations on the data formed in the first step for the multiphase multicomponent flow module and the mechanical module respectively. Specifically, it includes the following steps:

[0116] (1) The calculation process of multiphase multicomponent flow in deep shale oil and gas reservoirs, that is, the process of solving the seepage equation includes the following steps 301 to 306:

[0117] Step 301: At the known initial time = 0, the reservoir pressure, temperature, and saturation distributions are known;

[0118] Step 302: Use the phase equilibrium module to calculate the physical property parameters of the oil, gas, and water phases;

[0119] Step 303: Solve the linear equation system to obtain the pressure distribution law at time + 1;

[0120] Step 304: Substitute into the water phase control equation and the saturation relationship to obtain the saturation distribution law of each phase at time + 1;

[0121] Step 305: Solve the formula J δ = − R1 , determine whether the residual of the seepage equation is less than . If not, return to step 303 for iterative calculation until the residual is less than ; Take the value of 1e -10 . J refers to in formula (22), and δ refers to the increment of the main variable in formula (23) at the p +(1) iterative step , R 1 represents the residual of the seepage equation.

[0122] Step 306: If it holds, that is, the residual of the seepage equation is less than , then = +1, enter the next time step, and repeat steps 302 - 304 to obtain the distribution laws of reservoir pressure and phase saturations, and the calculation is completed.

[0123] The calculation process of the mechanical module, that is, the solution process of the mechanical equation includes the following steps 401 - 405:

[0124] Step 401: Obtain the distribution of formation rock physical property parameters and stress parameters at the initial time =0 according to the data in the first step;

[0125] Step 402: Give the initial values of the distribution laws of formation pressure and temperature at time ;

[0126] Step 403: Use formulas (11) - (13) to calculate the plastic deformation of the matrix and fractures caused by stress;

[0127] Step 404: Solve and determine whether the residual of the mechanical equation is less than ( Take the value of 1e -10 ). If not, return to step 403 for iterative calculation until the residual is less than ;

[0128] Step 405: If it holds, then = +1, enter the next time step, and repeat steps 402 - 404 to obtain the plastic deformation conditions under different temperature and pressure, and the calculation is completed.

[0129] Third step: The above-mentioned pressure-driven oil displacement and storage numerical simulation module T4 is specifically used to implement the following steps 501 - 504:

[0130] Step 501: In each time step, fix the current in-situ stress field, use the finite volume method to iteratively solve the seepage equation to obtain the distribution of the fluid pressure field, and update the matrix and fracture porosities in real time during the iteration process;

[0131] Step 502: Based on the distribution of the fluid pressure field, use the finite element method to iteratively solve the mechanical equation to obtain the distribution of the in-situ stress field, and update the matrix and fracture porosities and permeabilities;

[0132] Step 503: Based on the distribution of the in-situ stress field, determine whether damage occurs in each grid cell, and update the permeability of the damaged grid cells;

[0133] Step 504: Repeat Step 501 and Step 502 until the coupled iteration converges, and enter the next time step.

[0134] Based on the fully implicit solution of the seepage equation by the finite volume method, the mechanical equation is solved by the finite element method, and the fluid-solid two-field iterative coupling is solved based on the fixed stress decomposition algorithm to establish a numerical solution method, forming a complete numerical simulation technology for CO 2 pressure-driven oil displacement and storage in deep shale reservoirs. The numerical calculation solution process of the fixed stress decomposition algorithm is as Figure 3 shown.

[0135] Fourthly, obtain the production data (water cut, oil volume) within the specified production time, and perform history matching with the exploited data of the deep shale reservoir.

[0136] The distribution of the pressure-driven stress is as Figure 7 shown, and the evolution of the damage factor after pressure-driven is as Figure 8 shown.

[0137] Figure 9 and Figure 10 show the history matching situations of the production wells Niu 6-x22, Niu 21-x2, Niu 21-x3, and Niu 21-x5 in this block. The simulated results of the daily oil production and water cut of the four production wells are in good agreement with the historical production data, further verifying the effectiveness and applicability of the numerical simulation technology.

[0138] The present application also provides an application scenario, which applies the above-mentioned numerical simulation technology system for carbon dioxide pressure drive enhanced oil recovery and storage. Specifically: The numerical simulation technology system for carbon dioxide pressure drive enhanced oil recovery and storage provided in this embodiment can be applied in the shale oil extraction scenario. The shale oil extraction scenario includes a data acquisition link, a numerical simulation link for carbon dioxide pressure drive enhanced oil recovery and storage, and a shale oil extraction link; the geological data of the target oilfield site enters the numerical simulation link for carbon dioxide pressure drive enhanced oil recovery and storage from the content production link, obtains the corresponding numerical simulation results, and enters the downstream shale oil extraction link. The numerical simulation technology system for carbon dioxide pressure drive enhanced oil recovery and storage provided in this embodiment belongs to the numerical simulation link for carbon dioxide pressure drive enhanced oil recovery and storage. Specifically, in the process of the numerical simulation link for carbon dioxide pressure drive enhanced oil recovery and storage of the target oilfield site, a geological model of the deep shale oil reservoir for carbon dioxide pressure drive can be constructed according to the geological data. 2 Based on the multiphase and multicomponent seepage model and the mechanical deformation model, and combined with the constitutive model of reservoir damage mechanics, a mathematical model for carbon dioxide pressure drive enhanced oil recovery and storage in the deep shale oil reservoir is established. 2 The seepage equation and the mechanical equation are solved, and the fluid-solid two-field iterative coupling solution is carried out based on the fixed stress decomposition algorithm to conduct the numerical simulation of carbon dioxide pressure drive enhanced oil recovery and storage in the deep shale oil reservoir, and the numerical simulation results are obtained. 2

[0139] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0140] In this article, specific examples are used to elaborate on the principle and implementation mode of the present application. The description of the above embodiments is only used to help understand the system of the present application and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.​

Claims

1. A CO2 pressure-driven oil recovery and storage numerical simulation technology system, characterized in that: The carbon dioxide pressure drive oil recovery and storage numerical simulation technology system includes: The geological data acquisition module is used to: obtain geological data at the target oil field site; The reservoir geological model building module is used to: build a reservoir geological model of the CO2 pressure drive process in deep shale reservoirs according to the geological data; A module for establishing a mathematical model of pressure-driven oil displacement and storage is used to establish a mathematical model of CO2 pressure-driven oil displacement and storage in deep shale reservoirs based on a multiphase and multicomponent seepage model and a mechanical deformation model, combined with a reservoir damage mechanical constitutive model; the mathematical model of CO2 pressure-driven oil displacement and storage in deep shale reservoirs includes a multiphase and multicomponent fluid seepage equation, a stress balance equation, an effective stress equation, a matrix porosity dynamic change relationship equation, and a permeability dynamic change relationship equation; The pressure-driven oil displacement and storage numerical simulation module is used to solve the seepage equation and mechanical equation, solve the fluid-solid field iterative coupling based on the constant stress decomposition algorithm, conduct numerical simulation of CO2 pressure-driven oil displacement and storage in deep shale reservoirs, and obtain numerical simulation results; The finite volume method is fully implicit in solving the residual form of the seepage equation: ； ； in, Represents a grid cell n Components exist The residual of the percolation equation at +1 time step, Indicated in +1 time step grid cell n and grid cells m The conductivity between express +1 time step grid cell m The flow potential of the oil phase, express +1 time step grid cell n The flow potential of the oil phase, express +1 time step grid cell m The flow potential of the gas phase, express +1 time step grid cell n The flow potential of the gas phase, Represents a grid cell n The water phase The residual of the percolation equation at +1 time step, Represents a grid cell n The set of adjacent grid cells; V is the volume of the fluid; is the porosity; represent the density of oil phase, gas phase and water phase respectively; is the saturation, and the subscripts o, g, and w represent the oil phase, gas phase, and water phase, respectively; For components The mole fraction of the component in the oil phase; For components The mole fraction of the component in the gas phase; The Newton-Raphson method is used to iteratively solve: ； ； In the formula, k represents the iteration step, represents the time step, l Indicates the main variable number, Indicates that the main variable is k +1 iteration increment, +1 indicates the current time step, x is the main variable; The residual form of the finite element method to solve the mechanical equation is: ； In the formula, represents the residual vector of the mechanical equation, ; is the differential operator matrix, is the shape function matrix; is the delta Dirac function vector, is the total area where stress is applied, is the matrix boundary, is the crack boundary, is the constant load on the crack boundary; is the Biot coefficient; is the total fluid pressure; is the rock density; is the acceleration due to gravity; The Newton-Raphson method is used to iteratively solve: ； 。 2. The carbon dioxide pressure-driven oil recovery and storage numerical simulation technology system according to claim 1 is characterized in that: The geological data include reservoir parameters, fluid physical property parameters and CO2 injection parameters.

3. The carbon dioxide pressure-driven oil recovery and storage numerical simulation technology system according to claim 1 is characterized in that: The reservoir geological model construction module specifically includes: According to the geological data, a reservoir geological model of the CO2 pressure drive process in deep shale reservoirs is constructed based on a structured network.

4. The carbon dioxide pressure-driven oil recovery and storage numerical simulation technology system according to claim 1 is characterized in that: The reservoir damage mechanics constitutive model is expressed as follows: ； in, is the effective stress tensor of rock, is the stress tensor, is the identity matrix, is the rock damage factor, is the elasticity tensor, is the strain tensor.

5. The carbon dioxide pressure-driven oil recovery and storage numerical simulation technology system according to claim 4 is characterized in that: The carbon dioxide pressure-driven oil recovery and storage numerical simulation technology system also includes a rock damage factor determination module, which is used to: determine the rock damage factor according to the reservoir tensile damage factor and the reservoir shear damage factor; the reservoir tensile damage factor and the reservoir shear damage factor are expressed as follows: ； ； in, is the reservoir tensile damage factor, is the maximum principal stress, is the uniaxial tensile strength of rock, is the reservoir shear damage factor, is the minimum principal stress, is the internal friction angle, is the uniaxial compressive strength of rock.

6. The carbon dioxide pressure drive oil recovery and storage numerical simulation technology system according to claim 5 is characterized in that: The rock damage factor determination module specifically includes: When the reservoir tensile damage factor is greater than or equal to 0, the relationship between the rock damage factor and the strain tensor is as follows: ； When the reservoir shear damage factor is greater than or equal to 0, the relationship between the rock damage factor and the strain tensor is as follows: ； in, is the change ratio of tensile strength, , is the residual tensile strength of rock, is the initial uniaxial tensile strength of rock, is the tensile damage strain threshold, is the ultimate tensile strain, is the shear damage strain threshold.

7. The carbon dioxide pressure drive oil recovery and storage numerical simulation technology system according to claim 1 is characterized in that: The pressure drive oil displacement and burial storage numerical simulation module specifically includes: Step 501: In each time step, the current geostress field is fixed, and the seepage equation is iteratively solved using the finite volume method to obtain the fluid pressure field distribution. The matrix and fracture porosity are updated in real time during the iteration process; Step 502: Based on the fluid pressure field distribution, the finite element method is used to iteratively solve the mechanical equation to obtain the ground stress field distribution, and update the matrix and fracture porosity and permeability; Step 503: Based on the distribution of the geostress field, determine whether each grid unit is damaged, and update the permeability of the damaged grid unit; Step 504: Repeat steps 501 and 502 until the coupled iteration converges and enter the next time step.

8. The carbon dioxide pressure drive oil recovery and storage numerical simulation technology system according to claim 1 is characterized in that: The numerical simulation results include reservoir pressure, saturation, oil production and water content.

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