Reservoir development method and device, apparatus, and medium based on pore-scale simulation

Abstract

This invention relates to a reservoir development method, apparatus, equipment, and medium based on pore-scale simulation, belonging to the field of oil and gas extraction technology. The method includes: constructing a three-dimensional digital core geometric model of the target reservoir block; meshing the three-dimensional digital core geometric model to obtain a geometric mesh model; performing flow simulation on the geometric mesh model to obtain a pore-scale multiphase flow model; and conducting pore-scale simulations of different injection methods based on the three-dimensional digital core geometric model and the pore-scale multiphase flow model to obtain the optimal injection scheme for reservoir development. The reservoir development method provided by this invention combines pore-scale simulation technology with reservoir development parameter optimization to quantitatively analyze the impact of injection parameters on oil displacement efficiency, predict the remaining oil distribution under different parameters at the microscale, clarify the microscopic mechanism of development parameter optimization, and provide theoretical basis and technical support for optimizing injection parameters and adjusting injection methods in offshore weak water drive reservoirs.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction technology, specifically to a reservoir development method, apparatus, equipment, and medium based on pore scale simulation, and particularly to a reservoir development method, apparatus, equipment, and medium for offshore weak water drive using pore scale numerical simulation. Background Technology

[0002] Currently, offshore oil fields are gradually becoming the main source of increased crude oil production, playing a key role in promoting the strategic goal of stabilizing crude oil production.

[0003] However, long-term development has made it increasingly difficult to improve the recovery rate of offshore oil fields. The average recovery rate is about 31%, the recovery degree is 19.89%, the overall water cut reaches 90.44%, and the oil production rate is only 1.12%.

[0004] Therefore, there is an urgent need to develop key technologies for enhanced oil recovery that are highly targeted and adapted to complex offshore geological conditions, so as to provide scientific support for stabilizing and increasing oil production and improving economic efficiency in oil fields.

[0005] Weak water drive reservoirs are a challenging type of reservoir in offshore oilfield development. They rely mainly on natural energy for extraction, and have low formation energy, weak formation water recharge capacity, and insufficient water injection pressure driving force.

[0006] Meanwhile, offshore weak water-drive reservoirs are usually accompanied by strong heterogeneity and complex pore structure, resulting in low water injection efficiency, complex distribution of remaining oil, and low recovery rate. This also makes it difficult for traditional macro-scale reservoir simulation or empirical models to characterize the displacement process under these conditions, and even more difficult to analyze the micro-mechanism of displacement methods such as water drive and gas drive. In other words, traditional development methods face problems such as low recovery rate and complex distribution of remaining oil in the development of offshore weak water-drive reservoirs.

[0007] In summary, there is an urgent need to propose a method that combines pore-scale simulation technology with reservoir development parameter optimization to quantitatively analyze the impact of injection parameters on oil displacement efficiency, predict the distribution of remaining oil under different parameters at the microscale, clarify the microscopic mechanism of development parameter optimization, provide theoretical basis and technical support for optimizing injection parameters and adjusting injection methods in offshore weak water drive reservoirs, and improve the overall development performance of weak water drive reservoirs. Summary of the Invention

[0008] In view of the problems existing in the prior art, the purpose of this invention is to provide a reservoir development method, apparatus, equipment and medium based on pore scale simulation, so as to solve the problems of low recovery rate and complex distribution of remaining oil faced by traditional development methods in the development of weak water drive reservoirs at sea, and thus achieve efficient development of weak water drive reservoirs.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a reservoir development method based on pore scale simulation, the development method comprising:

[0011] Construct a three-dimensional digital core geometric model of the target block reservoir;

[0012] The three-dimensional digital core geometric model is meshed to obtain a geometric mesh model;

[0013] A flow simulation was performed on the geometric mesh model to obtain a pore-scale multiphase flow model;

[0014] Based on a three-dimensional digital core geometric model and a pore-scale multiphase flow model, pore-scale simulations of different injection methods were conducted to study the influence of injection methods on displacement effect and residual oil distribution, and to obtain the optimal injection scheme for reservoir development.

[0015] The reservoir development method provided by this invention combines pore-scale simulation technology with reservoir development parameter optimization to quantitatively analyze the impact of injection parameters on oil displacement efficiency, predict the distribution of remaining oil under different parameters at the microscale, clarify the microscopic mechanism of development parameter optimization, provide guidance for macroscopic reservoir engineering design, and provide theoretical basis and technical support for optimizing injection parameters and adjusting injection methods in offshore weak water drive reservoirs, thereby improving the overall development performance of weak water drive reservoirs.

[0016] As a preferred technical solution of the present invention, the construction process of the three-dimensional digital core geometric model includes:

[0017] CT scans were performed on core samples from the target oil reservoir to obtain images of the core's micropore structure. These images were then processed to obtain a three-dimensional digital core geometric model.

[0018] As a preferred technical solution of the present invention, the image processing includes: sequential image filtering, threshold segmentation, and binarization.

[0019] As a preferred technical solution of the present invention, the mesh division includes: regular mesh division and irregular mesh division.

[0020] As a preferred technical solution of the present invention, the flow simulation is performed using the fluid volume method.

[0021] As a preferred technical solution of the present invention, the relationships used in the flow simulation include:

[0022] ;

[0023] ;

[0024] In the formula, Here, ρ is the vector differential operator; u is the velocity vector, m / s; P is the pressure, Pa; ρ is the density, kg / m³. 3 g is the acceleration due to gravity, 9.81 m / s². 2 μ is viscosity, mPa·s; F sa The interfacial force acting on the phase interface, N / m 3 ;

[0025] ;

[0026] In the formula, u c The compression rate is expressed in m / s and depends on the maximum velocity in the interface domain; α represents the fluid volume fraction.

[0027] ;

[0028] ;

[0029] In the formula, ρ w The density of the aqueous phase is kg / m³. 3 ;ρ o Here is the density of the oil phase, kg / m³ 3 μ w The viscosity of the aqueous phase is mPa·s; μ o ρ is the viscosity of the oil phase, mPa·s;

[0030] ;

[0031] In the formula, F sa Γ represents the interfacial force; τ represents the integration region; Γ represents the two-phase interface. x is the Dirac-delta function acting on the two-phase interface; x is the spatial coordinate point within the computational domain; x S is the coordinate point on the interface between the two phases; k is the interface curvature; σ is a unit vector; σ is the interfacial tension between the two phases, in N / m. 3 ;

[0032] The expression for the interface curvature k is:

[0033] ;

[0034] Contact angle satisfy:

[0035] ;

[0036] In the formula, It is a unit vector perpendicular to the interface between the two phases; It is a unit vector perpendicular to the solid wall.

[0037] As a preferred technical solution of the present invention, the pore-scale multiphase flow model uses a laminar two-phase flow model between flat plates to compare and analyze the numerical simulation results with the analytical solutions.

[0038] Secondly, the present invention provides a reservoir development apparatus based on pore scale simulation, the reservoir development apparatus comprising:

[0039] The building module is used to construct a three-dimensional digital core geometry model of the target block reservoir;

[0040] The meshing module is used to mesh the three-dimensional digital core geometric model to obtain a geometric mesh model.

[0041] The flow simulation module is used to perform flow simulation on the geometric mesh model to obtain a pore-scale multiphase flow model.

[0042] The injection simulation module is used to conduct pore-scale simulations of different injection methods based on a three-dimensional digital core geometric model and a pore-scale multiphase flow model. It studies the influence of injection methods on displacement effect and residual oil distribution, and obtains the optimal injection scheme for reservoir development.

[0043] Thirdly, the present invention provides an electronic device comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the reservoir development method based on pore scale simulation as described in the first aspect.

[0044] Fourthly, the present invention provides a computer storage medium storing computer-executable instructions, which, when executed by a processor, implement the reservoir development method based on pore scale simulation described in the first aspect.

[0045] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0046] (1) Based on microscopic CT scanning experiments, this invention obtains microscopic pore data of rock cores and constructs a high-precision digital rock core geometric network model. This model can accurately reconstruct the microscopic structure of the rock core, laying the foundation for high-precision simulation of the microscopic displacement process of rock cores in offshore weak water-drive reservoirs.

[0047] (2) This invention is based on pore-scale simulation, combined with digital core modeling and volumetric fluid flow (VOF) method, to accurately simulate the flow behavior of multiphase fluids in the pore structure of complex oil reservoirs. A digital core micro-flow simulation technology has been established, which can observe and quantitatively characterize the migration process of injected fluid in pores in real time, which helps to reveal the micro-dynamic mechanism of injected fluid in depth, thereby realizing high-precision simulation of the displacement process of offshore weak water drive oil reservoirs.

[0048] (3) This invention is designed for the development characteristics of offshore weak water drive reservoirs, and reveals the influence law of different injection methods on the final recovery rate. It can provide technical support for the development scheme design of offshore weak water drive reservoirs and guide the optimization of injection parameters. It has significant engineering application potential and economic value. Attached Figure Description

[0049] Figure 1 This is an example flowchart of a reservoir development method based on pore scale simulation provided by an embodiment of the present invention;

[0050] Figure 2 This is an example diagram of a reservoir development device based on pore scale simulation provided in an embodiment of the present invention;

[0051] Figure 3 This is a schematic diagram of an electronic device provided in an embodiment of the present invention;

[0052] Figure 4 This is a flowchart of the reservoir development method based on pore scale simulation in Embodiment 1 of the present invention;

[0053] Figure 5 This is a pore structure model diagram extracted from digital core CT scan results in Embodiment 1 of the present invention;

[0054] Figure 6 This is a model diagram of the pore structure after meshing in Embodiment 1 of the present invention;

[0055] Figure 7 This is a comparison chart of the numerical simulation results and analytical solutions of the laminar two-phase flow model between flat plates in Embodiment 1 of the present invention;

[0056] Figure 8 This is a simulation result diagram of fluid distribution under different displacement methods in Embodiment 1 of the present invention;

[0057] Figure 9 This is a distribution map of residual oil saturation in slices under different displacement methods in Embodiment 1 of the present invention;

[0058] Figure 10 This is a comparison chart of the recovery degree under different displacement methods in Embodiment 1 of the present invention.

[0059] In the picture:

[0060] 100 - Building module, 200 - Partitioning module, 300 - Flow simulation module, 400 - Injection simulation module;

[0061] 10-Electronic device, 11-Processor, 12-ROM, 13-RAM, 14-Bus, 15-I / O interface, 16-Input unit, 17-Output unit, 18-Storage unit, 19-Communication unit.

[0062] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0063] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0064] I. This embodiment provides a reservoir development method based on pore scale simulation, the process of which is as follows: Figure 1 As shown, the development method includes:

[0065] Construct a three-dimensional digital core geometric model of the target block reservoir;

[0066] The three-dimensional digital core geometric model is meshed to obtain a geometric mesh model;

[0067] A flow simulation was performed on the geometric mesh model to obtain a pore-scale multiphase flow model;

[0068] Based on a three-dimensional digital core geometric model and a pore-scale multiphase flow model, pore-scale simulations of different injection methods were conducted to study the influence of injection methods on displacement effect and residual oil distribution, and to obtain the optimal injection scheme for reservoir development.

[0069] The construction process of the three-dimensional digital core geometric model includes: performing CT scanning on core samples of the target block reservoir to obtain images of the core micropore structure, and performing image processing on the core micropore structure images to obtain a three-dimensional digital core geometric model.

[0070] The image processing includes sequential image filtering, thresholding, and binarization.

[0071] In this invention, the specific filtering method can be reasonably selected according to the conventional requirements in the field. For example, non-local mean filtering can be used. This method uses the similarity of the pixel blocks around two pixels as the weight for pixel smoothing. The greater the similarity, the greater the probability that the pixels are in the same phase. Noise will cause weight abnormalities, which can protect edge information well while reducing noise.

[0072] In this invention, the threshold segmentation method is designed reasonably according to the conventional requirements in the field. For example, the grayscale CT image is segmented according to the histogram of the intensity value and grayscale value of each phase, i.e., threshold segmentation. The accuracy of the segmentation is verified by comparing the results of the segmented image with the core porosity and permeability test results.

[0073] In this invention, after threshold segmentation is completed, the image is converted into a binary image, where white represents the pore area and black represents the solid skeleton area.

[0074] The grid division includes regular grid division and irregular grid division.

[0075] In this invention, the meshing is based on a constructed three-dimensional digital core model. Each pixel or voxel represents a tiny volume unit within the core in three-dimensional space. The model can clearly display the pore morphology and distribution of the core through the geometric information of the pore structure.

[0076] In this invention, the mesh generation method can be handled according to conventional requirements in the field. For example, the original 3D image data can be processed and segmented using Fiji software, and the reconstructed 3D model can be saved in STL file format. Then, OpenFOAM software can be used for subsequent processing. BlockMesh is a mesh generation method in OpenFOAM, suitable for generating structured meshes. It can generate regular hexahedral meshes, suitable for processing regions with regular geometric shapes. SnappyHexMesh is a tool in OpenFOAM used to generate irregular meshes. It can handle complex geometric structures and generate irregular meshes on the surface of porous structures, which is particularly important for core structures with complex pore distributions and morphologies. By extracting surface features of the solid skeleton in the digital core model, the surface details of the object can be accurately captured, and suitable geometric boundaries for mesh generation can be generated. Then, an appropriate mesh refinement strategy is adopted to perform more detailed mesh generation in the porous structure region, especially at the pore boundaries, where the refined mesh can better capture fluid flow and interface behavior. Finally, the mesh is generated to ensure effective simulation of the flow characteristics of the porous region.

[0077] In this invention, the quality of the mesh generation can be ensured by checking orthogonality and cell uniformity.

[0078] The flow simulation is performed using the fluid volume method.

[0079] In this invention, the exemplary process of flow simulation using the fluid volume method is as follows:

[0080] The Navier-Stokes equations are partial differential equations used to describe the motion of viscous fluids and are one of the core equations in fluid mechanics. They incorporate the effects of fluid viscosity, pressure gradient, inertial forces, and external forces, and can accurately simulate the motion behavior of fluids under different conditions. By coupling the continuity equation and the Navier-Stokes equations, the pressure and velocity of incompressible two-phase flow of Newtonian fluids can be solved. The governing equations are expressed as follows:

[0081] ;

[0082] ;

[0083] In the formula, Here, ρ is the vector differential operator; u is the velocity vector, m / s; P is the pressure, Pa; ρ is the density, kg / m³. 3 g is the acceleration due to gravity, 9.81 m / s². 2 μ is viscosity, mPa·s; F sa The interfacial force acting on the phase interface, N / m 3 .

[0084] In this invention, the core idea of ​​the fluid volume fraction (VOF) method is to describe the proportion of each fluid phase in each computational cell using a scalar field (volume fraction). This allows for the tracking of phase interfaces between fluids and the accurate simulation of multiphase flow. This method can obtain the location of the oil-water interface, the distribution of fluids, and their changes over time. In the VOF method, the fluid volume fraction (α) represents the proportion of each fluid in each computational cell. For a computational cell composed of two or more fluids, the volume fraction value determines the fluid distribution, ranging from 0 to 1. When α = 1, the cell is entirely composed of one fluid (e.g., oil phase); when α = 0, the cell is entirely composed of another fluid (e.g., water phase); and when 0 < α < 1, the cell is a mixing zone of two fluids.

[0085] The variation of fluid volume fraction α with time and space is influenced by fluid flow; therefore, its variation needs to be described by a phase transport equation for fluid volume fraction (α). The expression for the phase transport equation of fluid volume fraction (α) is as follows:

[0086] ;

[0087] In the formula, u c The compression velocity is expressed in m / s and depends on the maximum velocity in the interface domain; α represents the fluid volume fraction.

[0088] To maintain the balance of mass and momentum among the phases, density ρ and viscosity μ can be expressed by the fluid volume fraction α:

[0089] ;

[0090] ;

[0091] In the formula, ρ w The density of the aqueous phase is kg / m³. 3 ;ρ o Here is the density of the oil phase, kg / m³ 3 μ w The viscosity of the aqueous phase is mPa·s; μ o ρ is the viscosity of the oil phase, mPa·s;

[0092] Interface force ;

[0093] In the formula, F sa Γ represents the interfacial force; τ represents the integration region; Γ represents the two-phase interface. x is the Dirac-delta function acting on the two-phase interface; x is the spatial coordinate point within the computational domain; x S is the coordinate point on the interface between the two phases; k is the interface curvature; σ is a unit vector; σ is the interfacial tension between the two phases, in N / m. 3 ;

[0094] The expression for the interface curvature k is:

[0095] ;

[0096] Contact angle satisfy:

[0097] ;

[0098] In the formula, It is a unit vector perpendicular to the interface between the two phases; It is a unit vector perpendicular to the solid wall.

[0099] The pore-scale multiphase flow model uses a laminar two-phase flow model between flat plates to compare and verify the numerical simulation results with the analytical solutions.

[0100] In this invention, a laminar two-phase flow model between flat plates is used to compare and analyze the numerical simulation results with the analytical solutions to verify the accuracy of the VOF simulation method, as exemplarily as follows:

[0101] Two immiscible fluids are set to be distributed between two infinitely long parallel plates. The channel extends to a height of 2b in the y-direction, and the centerline of the channel is located at y = 0. Fluid 1 occupies the region 0 < |y| < a, and fluid 2 occupies the region a < |y| < b. Two constant pressure gradients G1 and G2 are applied to fluid 1 and fluid 2 respectively. The densities ρ of the two fluids are the same, and the viscosities are μ1 and μ2 respectively. Assuming that the fluid flow between the parallel plates reaches a steady state and satisfies Poiseuille flow, within the positive semi-axis range between the infinitely long parallel plates, the analytical solution of the velocity distribution of the cross-section along the y-direction can be expressed as:

[0102] ;

[0103] In the formula, ; ; ; ; ; a is the longitudinal extension height of fluid 1, μm; b is the longitudinal extension height of fluid 2, μm; G1 represents the pressure gradient of fluid 1, Pa / m; G2 represents the pressure gradient of fluid 2, Pa / m; μ1 is the viscosity of fluid 1, mPa·s; μ2 is the viscosity of fluid 2, mPa·s.

[0104] In this invention, pore-scale simulations of different injection methods are carried out to study the effects of different injection methods on the displacement effect and the distribution of remaining oil. The simulation process is based on the constructed digital core model and the VOF method. By calculating the volume fraction equation of the fluid, the dynamic changes of the oil-water interface are traced, and the seepage process of the water phase in the pores and the changes of the fluid front are analyzed.

[0105] In this invention, the optimal injection scheme for reservoir development can be determined by selecting the injection method based on actual conditions. For example, different injection methods such as water drive, partially miscible drive, fully miscible drive, and water drive-to-gas drive can be implemented to influence oil displacement. Water drive is a commonly used reservoir development method that maintains reservoir pressure by injecting water, driving crude oil towards production wells. Miscible displacement is a highly efficient enhanced oil recovery (EOR) technology in oil and gas field development. Its core is to inject a fluid that can form a miscible phase with crude oil into the formation, eliminating the interfacial tension between crude oil and the displacement agent, improving crude oil fluidity, and thus efficiently displacing residual oil retained in rock pores after conventional extraction to production wells. It is particularly effective in low-permeability reservoirs and complex pore structures. Specifically, it can be divided into partially miscible drive and fully miscible drive. Partially miscible drive refers to fluids that are not completely mixed, with a clear interface remaining. Fully miscible drive refers to fluids that are completely mixed with crude oil to form a homogeneous fluid with almost zero interfacial tension. The interaction between the two fluid phases is enhanced, enabling uniform displacement of crude oil. Water-to-gas flooding is a synergistic displacement method that combines water and gas flooding. In the process of water-to-gas flooding, the water phase is first injected into the reservoir, driving the fluid in the oil layer to flow along high-permeability channels. Then, gas is injected, and through the high fluidity of the gas, it reaches areas that have not been displaced by the water phase, improving fluid distribution and thus increasing the recovery rate.

[0106] II. This embodiment provides a reservoir development device based on pore scale simulation, such as... Figure 2 As shown, the reservoir development apparatus includes:

[0107] Module 100 is used to construct a three-dimensional digital core geometric model of the target block reservoir;

[0108] The meshing module 200 is used to mesh the three-dimensional digital core geometric model to obtain a geometric mesh model.

[0109] The flow simulation module 300 is used to perform flow simulation on the geometric mesh model to obtain a pore-scale multiphase flow model.

[0110] The injection simulation module 400 is used to conduct pore-scale simulations of different injection methods based on a three-dimensional digital core geometric model and a pore-scale multiphase flow model. It studies the influence of injection methods on displacement effect and residual oil distribution, and obtains the optimal injection scheme for reservoir development.

[0111] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0112] III. This embodiment provides an electronic device intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (e.g., helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0113] like Figure 3 As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded into the RAM 13 from storage unit 18. The RAM 13 can also store various programs and data required for the operation of the electronic device 10. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An I / O interface 15 is also connected to the bus 14.

[0114] Multiple components in electronic device 10 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of displays, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0115] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, central processing unit (CPU), graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, digital signal processors (DSPs), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as reservoir development methods based on pore scale simulation.

[0116] In some embodiments, the reservoir development method based on pore-scale simulation can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the reservoir development method based on pore-scale simulation described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to perform the reservoir development method based on pore-scale simulation by any other suitable means (e.g., by means of firmware).

[0117] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0118] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0119] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0120] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0121] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or middleware components (e.g., application servers), or frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0122] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0123] The server provided in this embodiment includes: a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the program, it implements a reservoir development method based on pore scale simulation.

[0124] Unless otherwise specifically stated, terms such as processing, calculation, operation, determination, display, etc., may refer to the actions and / or processes of one or more processing or computing systems or similar devices that represent the manipulation and conversion of data representing physical (e.g., electronic) quantities within the registers or memory of the processing system into other data similarly representing physical quantities within the memory, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals can be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0125] Those skilled in the art will also understand that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with embodiments of the present invention can all be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate the interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps described above are generally described in terms of their functionality. Whether this functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art can implement the described functionality in alternative ways for each specific application; however, such implementation decisions should not be construed as departing from the scope of protection of the present invention.

[0126] The steps of the methods or algorithms described in conjunction with the embodiments herein can be directly embodied in hardware, software modules executed by a processor, or a combination thereof. The software modules can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. Alternatively, the processor and storage medium can exist as discrete components in the user terminal.

[0127] For software implementation, the techniques described in this invention can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described in this application. This software code can be stored in memory units and executed by a processor. The memory units can be implemented within the processor or externally; in the latter case, they are communicatively coupled to the processor via various means, as is well known in the art.

[0128] IV. To illustrate the effects of the reservoir development method based on pore scale simulation provided by this invention, the following example is used for explanation:

[0129] Example 1

[0130] This embodiment provides a reservoir development method based on pore scale simulation, the process of which is as follows: Figure 4 As shown, the details are as follows:

[0131] 1) CT scans were performed on core samples from the target block reservoir to obtain images of the core micropore structure. Through image processing such as image filtering, threshold segmentation, and binarization, a preliminary three-dimensional digital core geometric model was constructed to ensure that the model accurately reflects the pore structure characteristics of the reservoir.

[0132] The core data in step (1) is based on actual reservoir formation parameters. The selected core sample has a porosity of 19.5% and a permeability of 27.6 × 10⁻⁶. -3 μm 2 The core samples obtained in this experiment were columnar cores with a diameter of 6 mm and a length of 4 mm. The X-ray CT scan resolution was 3 μm, and the scan results were 8-bit grayscale images, with each voxel having 2... 8 (i.e., 256) levels of grayscale, the filtering process uses non-local mean filtering, which can effectively protect edge information while reducing noise.

[0133] Before analysis, grayscale CT images were thresholded and segmented based on histograms of intensity and grayscale values ​​for each phase. The accuracy of the segmentation was verified by comparing the segmented images with core porosity and permeability test results. In this study, porosity and permeability were selected as constraints.

[0134] After thresholding, the image is converted into a binary image, where white represents the porous region and black represents the solid skeleton region. The image obtained after binarization can more clearly reflect the pore structure of the core and facilitates subsequent geometric model reconstruction. Considering the actual model size and subsequent computing power requirements, this embodiment selects a 150×150×350 voxel region as the characterization unit, with a single voxel resolution of 3.0 μm.

[0135] Pore ​​structure model extracted from digital core CT scan results, such as Figure 5 As shown.

[0136] (2) Using Avizo and OpenFOAM numerical simulation software, the constructed digital core geometric model is meshed to generate a high-precision geometric mesh model that conforms to the actual pore structure, so as to ensure that the simulation results can match the micropore structure of the actual reservoir, thereby ensuring the accuracy of the simulation results.

[0137] In step (2), the digital core pore structure is accurately transformed into a high-quality mesh model suitable for numerical simulation by combining Avizo software with the blockMesh and snappyHexMesh methods in OpenFOAM. First, Avizo is used to preprocess the CT scan images to accurately extract the geometric features of the pores and core skeleton. Then, the blockMesh method is used to generate a structured mesh, which is suitable for meshing regular parts. For complex pore structures, the snappyHexMesh method is used to generate unstructured meshes, especially at pore boundaries and complex regions, to improve simulation accuracy. Mesh quality is ensured by checking orthogonality and element uniformity. The accuracy of the mesh is guaranteed in both small-scale and large-scale pore regions.

[0138] Ultimately, the grid data is stored in the OpenFOAM standard format, providing a foundation for subsequent fluid flow simulations and ensuring high-precision capture of fluid behavior and interface changes during the simulation.

[0139] The pore structure model after digital core meshing is as follows: Figure 6 As shown.

[0140] (3) Based on the constructed high-precision geometric mesh model, the volumetric fluid flow (VOF) method is used for flow simulation to establish a pore-scale multiphase flow model, characterizing the interaction, interface dynamics, and flow mechanism between different fluid phases, providing microscale data support for subsequent development and optimization. At the beginning of the simulation, the computational domain is initialized to be in a saturated oil state, and a constant inlet volumetric flow rate is given. In the numerical solution loop, the α field is first updated by solving the volume fraction equation, thereby realizing the capture and position update of the oil-water interface; then, the density and viscosity distribution of the entire domain are reconstructed according to the latest phase distribution. Combining the obtained physical properties, the surface tension acting on the interface is calculated and substituted into the NS equations for pressure-velocity coupling solution, and finally the velocity vector u and pressure distribution P of the current step are obtained through iteration.

[0141] In step (3), the VOF method defines a fluid volume fraction (α) in each computational cell to represent the proportion of a certain fluid (such as oil, gas or water) in that cell.

[0142] In this embodiment, if the control unit is entirely composed of the aqueous phase, the volume fraction is 1; if it is entirely composed of the oil phase, the volume fraction is 0. The volume fraction at the interface within the unit is between 0 and 1, meaning the unit's interior is a mixing zone of the two fluids. In this way, the VOF method can dynamically track changes in the fluid phase interface and adapt to the complex interfacial behavior in multiphase flow processes.

[0143] In this embodiment, a digital core model is used to simulate the distribution of fluid in a complex pore structure and its dynamic process over time. The VOF solver in the OpenFOAM platform is used to simulate the flow behavior of the fluid by solving the continuity equation and the Navier-Stokes equation. At the same time, physical parameters such as fluid viscosity, density, and interfacial tension are introduced to simulate the interfacial forces between two-phase flows and the interaction between the fluids.

[0144] (4) A laminar two-phase flow model between parallel plates is adopted. By comparing the numerical simulation results with the analytical solution, the accuracy of the VOF method in simulating the oil-water interface flow is verified, proving that the adopted VOF numerical method can accurately simulate the oil-water two-phase flow and its interface evolution behavior.

[0145] The specific steps for model verification in step (4) are as follows: First, the oil-water two-phase flow is simulated using a parallel plate laminar two-phase flow model, with fluid 1 and fluid 2 occupying different regions between the parallel plates. To simplify the calculation, the following settings are adopted: fluids with different viscosities are selected, with the viscosity of fluid 1 being μ1 = 4 mPa·s and the viscosity of fluid 2 being μ2 = 50 mPa·s. The two fluids are set to have the same density, ρ1 = ρ2 = 1000 kg / m³, which simplifies the influencing factors in the flow process.

[0146] Different pressure gradients are applied to the two fluids, G1 = 1 × 10⁻⁶ 6 Pa / m is applied to fluid 1, while G2=0 is applied to fluid 2. This setting is designed to simulate fluid flow behavior driven by pressure.

[0147] The classic Poiseuille flow solution was employed, which analytically describes the velocity distribution of the fluid between parallel plates under a constant pressure gradient. In the two-phase flow, the numerical solution was obtained using the VOF method, simulating the flow behavior of the oil-water two-phase fluid between the parallel plates and obtaining the velocity distribution at each location. The numerical simulation results were compared in detail with the analytical solution, specifically revealing the changes in the velocity gradient between the parallel plates.

[0148] The comparison results between numerical simulation results and analytical solutions, such as... Figure 7 As shown, the velocity distribution obtained by the VOF method is highly consistent with the Poiseuille flow solution, and the velocity distribution and pressure changes of the fluid are also consistent with the analytical solution. The consistency between the simulation results and the classical analytical solution verifies the effectiveness of the model used and ensures the accuracy of the VOF method in subsequent complex reservoir flow simulations.

[0149] The verification process shows that the numerical simulation method used in this invention has good stability and accuracy, and can be used for accurate simulation of multiphase flow in actual oil reservoir development, providing a scientific basis for oilfield development.

[0150] (5) Based on the verification of the laminar two-phase flow model, pore-scale simulations of different injection methods were carried out to implement the application effects of four injection methods—water drive, partial miscible drive, fully miscible drive, and water drive to gas drive—in weak water drive reservoirs, so as to provide the optimal injection scheme for reservoir development.

[0151] In step (5), based on the constructed digital core model, the VOF method was used to simulate multiphase flow and systematically study the effects of different injection methods on flow behavior, displacement efficiency and residual oil distribution.

[0152] In this embodiment, the injected gas is CH4, which has a density of 144.35 kg / m³ and a viscosity of 2.12 × 10⁻⁶ at 120°C and 30 MPa. -5 Pa·s designed four CH4 oil displacement schemes:

[0153] Water drive, partially miscible drive, fully miscible drive, and water drive to gas-injected miscible drive (i.e., first injecting 0.5 PV of water and then injecting 0.5 PV of gas).

[0154] In the simulation, the injection rate was 0.001 m / s, the interfacial tension was set to 0.01 mN / m for partial miscible displacement, and the diffusion coefficient was 1 × 10⁻⁶. -10 m2 / s, with an interfacial tension of 0 and a diffusion coefficient of 1×10⁻⁶ for fully miscible phase displacement. -9 m 2 / s.

[0155] Simulation results of fluid distribution under different displacement methods are as follows: Figure 8 As shown in the figure, yellow represents the gas phase, blue represents the water phase, and red represents the oil phase;

[0156] The residual oil saturation distribution of slices under different displacement methods is as follows: Figure 9 As shown;

[0157] Comparison of recovery rates under different displacement methods is as follows: Figure 10 As shown.

[0158] based on Figures 8-10 It can be seen that partial miscible flooding has the lowest recovery rate, only 30.9%, with severe gas channeling and a large amount of residual oil in the reservoir; miscible flooding promotes a steady increase in recovery rate through dissolution and viscosity reduction; water flooding effect is between partial miscible flooding and miscible flooding; and switching to miscible gas flooding after water flooding can significantly expand the swept volume and achieve the best displacement effect, with a recovery rate of 49.3%.

[0159] In areas where water injection development is ineffective, switching from water-driven to gas-driven development yields better results, indicating that water-gas synergistic displacement significantly improves sweep efficiency and micro-displacement efficiency.

[0160] In summary, the proposed optimization method for weak water-drive reservoir development based on pore scale simulation has significant application prospects.

[0161] The present invention is described in detail through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0162] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0163] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0164] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A reservoir development method based on pore scale simulation, characterized in that, The development method includes: Construct a three-dimensional digital core geometric model of the target block reservoir; The three-dimensional digital core geometric model is meshed to obtain a geometric mesh model; A flow simulation was performed on the geometric mesh model to obtain a pore-scale multiphase flow model; Based on a three-dimensional digital core geometric model and a pore-scale multiphase flow model, pore-scale simulations of different injection methods were conducted to study the influence of injection methods on displacement effect and residual oil distribution, and to obtain the optimal injection scheme for reservoir development.

2. The reservoir development method as described in claim 1, characterized in that, The construction process of the three-dimensional digital core geometric model includes: CT scans were performed on core samples from the target oil reservoir to obtain images of the core's micropore structure. These images were then processed to obtain a three-dimensional digital core geometric model.

3. The reservoir development method as described in claim 2, characterized in that, The image processing includes sequential image filtering, thresholding, and binarization.

4. The reservoir development method as described in claim 1, characterized in that, The grid division includes: regular grid division and irregular grid division.

5. The reservoir development method as described in claim 1, characterized in that, The flow simulation was performed using the fluid volume method.

6. The reservoir development method as described in claim 5, characterized in that, The relationships used in the flow simulation include: ； ； In the formula, Here, ρ is the vector differential operator; u is the velocity vector, m / s; P is the pressure, Pa; ρ is the density, kg / m³. 3 g is the acceleration due to gravity, 9.81 m / s². 2 μ is viscosity, mPa·s; F sa The interfacial force acting on the phase interface, N / m 3 ; ； In the formula, u c The compression rate is expressed in m / s and depends on the maximum velocity in the interface domain; α represents the fluid volume fraction. ； ； In the formula, ρ w The density of the aqueous phase is kg / m³. 3 ;ρ o Here is the density of the oil phase, kg / m³ 3 μ w The viscosity of the aqueous phase is mPa·s; μ o ρ is the viscosity of the oil phase, mPa·s; ； In the formula, F sa Γ represents the interfacial force; τ represents the integration region; Γ represents the two-phase interface. x is the Dirac-delta function acting on the two-phase interface; x is the spatial coordinate point within the computational domain; x S is the coordinate point on the interface between the two phases; k is the interface curvature; σ is a unit vector; σ is the interfacial tension between the two phases, in N / m. 3 ; The expression for the interface curvature k is: ； Contact angle satisfy: ； In the formula, It is a unit vector perpendicular to the interface between the two phases; It is a unit vector perpendicular to the solid wall.

7. The reservoir development method as described in claim 1, characterized in that, The pore-scale multiphase flow model uses a laminar two-phase flow model between flat plates to compare and verify the numerical simulation results with the analytical solutions.

8. A reservoir development device based on pore scale simulation, characterized in that, The reservoir development facility includes: The building module is used to construct a three-dimensional digital core geometry model of the target block reservoir; The meshing module is used to mesh the three-dimensional digital core geometric model to obtain a geometric mesh model. The flow simulation module is used to perform flow simulation on the geometric mesh model to obtain a pore-scale multiphase flow model. The injection simulation module is used to conduct pore-scale simulations of different injection methods based on a three-dimensional digital core geometric model and a pore-scale multiphase flow model. It studies the influence of injection methods on displacement effect and residual oil distribution, and obtains the optimal injection scheme for reservoir development.

9. An electronic device, characterized in that, The electronic device includes: At least one processor; and a memory communicatively connected to said at least one processor; The memory stores a computer program that can be executed by the at least one processor, which is then executed by the at least one processor to enable the at least one processor to perform the reservoir development method based on pore scale simulation as described in any one of claims 1-7.

10. A computer storage medium, characterized in that, The computer storage medium stores computer-executable instructions, which, when executed by a processor, implement the reservoir development method based on pore scale simulation as described in any one of claims 1-7.

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