Microcosmic water drive numerical simulation result interface flow field visualization method and system

Abstract

The invention provides a microcosmic water flooding numerical simulation result interface flow field visualization method and system, and the method comprises the steps: S1, building a mathematical model and a solving method of microcosmic water flooding, carrying out the numerical simulation of a water flooding process, and obtaining the numerical simulation result data; s2, establishing a mapping relation between a background grid and a physical quantity field according to the numerical simulation result data; s3, performing clear reconstruction and flow field segmentation on the oil-water two-phase interface to obtain a clear field of the oil phase or the water phase; s4, triangularization processing is carried out according to the space surface of the clear field, and rendering is carried out; and S5, repeating the steps S3 to S4, realizing reconstruction and rendering of another phase field, and completing layer superposition. The problem that post-processing of a microscopic numerical simulation result relates to partial physical field rendering and multi-layer superposition is solved, and clear capture of a microscopic oil-water interface is achieved.

Description

Technical Field

[0001] The invention relates to the field of microscopic oil reservoir numerical simulation, and in particular to a method and system for visualizing interface flow field of microscopic water drive numerical simulation results. Background Art

[0002] The numerical simulation process of water flooding in micro-reservoirs is to divide the physical model of the micro-pore structure into computational domain grids by means of computational fluid dynamics, and then numerically solve the oil-water behavior in the micro-pore structure, and finally obtain physical information data sets such as oil-water distribution, velocity distribution, and pressure distribution.

[0003] These GB-level or even TB-level data sets contain grid and physical quantity information. The original data sets need to be normalized through data preprocessing, and then mapped into geometric primitives using computer graphics methods. Finally, the geometric data is converted into graphic image data for display in the drawing stage, which is also an indispensable part of the entire numerical simulation.

[0004] Generally speaking, existing data post-processing algorithms are mainly based on macroscopic numerical simulation results, and their usage scenarios, focus, and compatibility are different from those of microscopic numerical simulations. In particular, unstructured grids are often used in microscopic reservoir simulations, and the mapping between grids and physical fields is complex. Next, when the interface display of multiple phases is involved in numerical simulation post-processing, the phase interfaces are often not clearly depicted. Finally, the simulation results involve multiple layers that are rendered separately and displayed in superposition.

[0005] In short, in the microscopic numerical simulation results, due to the huge amount of data, complex data types and the complexity of the physical characteristics themselves, how to accurately describe and display the data results through intuitive visualization methods is the key to summarizing and analyzing the oil and water movement behavior in the microscopic reservoir pore structure. This is also the basis for further proposing measures to improve reservoir recovery. Summary of the invention

[0006] In view of the above problems, the present invention is proposed to provide a method and system for visualizing the interface flow field of microscopic water flooding numerical simulation results, which overcomes the above problems or at least partially solves the above problems.

[0007] According to one aspect of the present invention, a method for visualizing the interface flow field of microscopic water flooding numerical simulation results is provided, and the visualization method comprises:

[0008] Step S1: establishing a mathematical model and solution method for microscopic water-to-oil displacement, performing numerical simulation of the water-to-oil displacement process, and obtaining numerical simulation result data;

[0009] Step S2: establishing a mapping relationship between the background grid and the physical quantity field according to the numerical simulation result data;

[0010] Step S3: clearly reconstructing the oil-water two-phase interface and segmenting the flow field to obtain a clear field of the oil phase or the water phase;

[0011] Step S4: performing triangulation processing and rendering according to the spatial surface of the clear field;

[0012] Step S5: Repeat steps S3 and S4 to achieve another phase field reconstruction and rendering, and complete layer overlay.

[0013] Optionally, the step S1: establishing a mathematical model of microscopic water-to-oil displacement specifically includes:

[0014] A mathematical model of microscopic oil-water two-phase distribution is established to simulate the dynamic behavior of oil-water two-phase in the microscopic pore structure of the core.

[0015] The oil-water two-phase tracking is implemented by using a fluid volume model.

[0016] Optionally, the mass conservation and momentum conservation equations of oil and water in the mathematical model are described by the following equations ① and ②:

[0017]

[0018]

[0019] Among them, ρ is the average density of the two phases; μ is the average density and dynamic viscosity coefficient of the two phases; u is the average velocity of the two phases; g is the gravitational acceleration, p d is the pressure, τ is the fluid stress tensor;

[0020] Optionally, the step S1 performs a numerical simulation of the water-to-oil process, and obtaining numerical simulation result data specifically includes:

[0021] The mathematical model is discretized on a grid based on a finite volume method, and an iterative solution is performed to obtain the calculation results of the numerical simulation in the microscopic reservoir pore structure.

[0022] Optionally, the step S2: establishing a mapping relationship between a background grid and a physical quantity field according to the numerical simulation result data specifically includes:

[0023] Establish a mapping relationship between the background grid unit body number and the value of the physical quantity at the center of the background grid unit body;

[0024] The mapping relationship is stored.

[0025] Optionally, the mapping relationship specifically includes: a corresponding relationship between grid points, grid surfaces, grid bodies and physical quantity data.

[0026] Optionally, the step S3: performing clear reconstruction and flow field segmentation on the oil-water two-phase interface to obtain a clear field of the oil phase or the water phase specifically includes:

[0027] Traverse all fluid grid cells to obtain the spatial position information of the center points of all grid cells and the stored physical quantity information;

[0028] Loop through all grid points to obtain the location information of all grid points and the neighbor relationship between grid points and grid cells;

[0029] Establish a mapping from grid cell values ​​to grid point values;

[0030] Determine the segmentation boundary of the field, loop all grid edges, and determine whether the given segmentation threshold is between the values ​​of two adjacent grid points based on the positional relationship between the grid points and the edges; if the segmentation threshold is between the values ​​of the two grid points, the interface and the edge intersect, otherwise they do not intersect;

[0031] Loop through all mesh edges that intersect the phase interface, and calculate the intersection points between the phase interface and the mesh edge by linear interpolation;

[0032] The dividing points on the grid surface are connected in sequence to obtain the dividing lines on the grid surface, and the dividing lines on adjacent grid surfaces are connected in sequence to reconstruct a clear oil-water boundary interface based on threshold segmentation to obtain a clear phase region.

[0033] Optionally, establishing the mapping from the grid cell value to the grid point value specifically includes: using an inverse distance weighted interpolation algorithm to implement the mapping from the grid cell value to the grid point value.

[0034] Optionally, the step S4: performing triangulation processing and rendering according to the spatial surface of the clear field specifically includes:

[0035] Traverse the mesh surface of the clear phase space. When the external boundary surface is a convex polygon, connect any two non-adjacent points of the convex polygon, and so on, until the polygon is divided into triangles that cannot be divided any more;

[0036] When the external boundary surface is a concave polygon, the ear-cut method is used to perform triangulation;

[0037] The triangulated mesh surface is rendered according to the set physical quantity values.

[0038] Optionally, the step S5: repeating the steps S3 and S4 to achieve another phase field reconstruction and rendering, and completing the layer overlay specifically includes:

[0039] Repeat steps 3-4 to obtain the layer of water-oil two-phase physical field;

[0040] The rendering result of the final physical quantity obtained by superimposing two layers.

[0041] On the other hand, the present invention further provides a microscopic water flooding numerical simulation result interface flow field visualization system, which uses a microscopic water flooding numerical simulation result interface flow field visualization method according to any one of claims 1 to 10, characterized in that the visualization system comprises:

[0042] Model building module, used to establish the mathematical model and solution method of microscopic water-to-oil displacement, conduct numerical simulation of the water-to-oil displacement process, and obtain numerical simulation result data;

[0043] A mapping relationship establishment module, used to establish a mapping relationship between a background grid and a physical quantity field according to the numerical simulation result data;

[0044] A segmentation module, used for clearly reconstructing the oil-water two-phase interface and segmenting the flow field to obtain a clear field of the oil phase or the water phase;

[0045] A triangulation processing module, used for performing triangulation processing and rendering according to the spatial surface of the clear field;

[0046] The overlay module is used to repeat step S3-step S4 to achieve another phase field reconstruction and rendering, and complete layer overlay.

[0047] The present invention provides a method and system for visualizing the interface flow field of microscopic water flooding numerical simulation results, and the visualization method includes: step S1: establishing a mathematical model and solution method of microscopic water flooding oil, performing numerical simulation of the water flooding oil process, and obtaining numerical simulation result data; step S2: establishing a mapping relationship between a background grid and a physical quantity field according to the numerical simulation result data; step S3: clearly reconstructing the oil-water two-phase interface and segmenting the flow field to obtain a clear field of the oil phase or water phase; step S4: triangulating the spatial surface of the clear field and rendering it; step S5: repeating steps S3-S4 to achieve reconstruction and rendering of another phase field, and completing layer superposition. The problem of partial physical field rendering and multi-layer superposition involved in the post-processing of microscopic numerical simulation results is solved, and the clear capture of the microscopic oil-water interface is achieved.

[0048] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0050] Figure 1 A flow chart of a method for visualizing interface flow field of microscopic water flooding numerical simulation results provided by an embodiment of the present invention;

[0051] Figure 2 A schematic diagram of a grid unit provided in an embodiment of the present invention;

[0052] Figure 3 A triangulated schematic diagram provided for an embodiment of the present invention;

[0053] Figure 4 A schematic diagram of layer rendering and overlay provided by an embodiment of the present invention;

[0054] Figure 5 A diagram of a physical model used in calculations provided in an embodiment of the present invention;

[0055] Figure 6 A visualization of numerical simulation results provided by an embodiment of the present invention;

[0056] Figure 7 This is a multi-layer overlay display result provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0057] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0058] The terms "comprises" and "having" and any variations thereof in the description embodiments, claims and drawings of the present invention are intended to cover non-exclusive inclusions, for example, including a series of steps or units.

[0059] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0060] The present invention proposes to construct a unified and operable data structure based on the microscopic oil-water numerical simulation results in the field of microscopic numerical simulation of oil reservoirs, and realizes a one-to-one mapping between grid information and physical field information. By developing a post-processing reconstruction algorithm for the two-phase interface, the problem of the field data in the traditional microscopic numerical simulation being unable to be clearly displayed during rendering is solved; finally, the problem of partial physical field rendering and multi-layer superposition involved in the post-processing of microscopic numerical simulation results is solved, and the clear capture of the microscopic oil-water interface is realized. It helps researchers to intuitively and efficiently analyze and understand the physical phenomena in microscopic reservoir numerical simulation and reveal the complex physical laws contained in the data results.

[0061] The purpose of the present invention is to provide a visualization method for a two-phase flow field with a clear interface of a microscopic reservoir water flooding numerical simulation result, comprising establishing a microscopic reservoir calculation domain model, building a microscopic numerical simulation mathematical model of a microscopic reservoir, reconstructing the two-phase interface of the simulation result, and superimposing multiple layers to finally achieve the rendering of a two-phase flow field with a clear interface.

[0062] like Figure 1 As shown, the present invention discloses a visualization algorithm for a clear interface flow field of microscopic water flooding numerical simulation results, comprising the steps of:

[0063] Step S1: establishing a mathematical model and solution method for microscopic water-to-oil displacement, performing numerical simulation of the water-to-oil displacement process, and obtaining numerical simulation result data;

[0064] Step S2: Read in the result data of the numerical simulation and establish a one-to-one mapping relationship between the background grid and the physical quantity field;

[0065] Step S3: Clearly reconstruct the oil-water two-phase interface and segment the flow field to obtain a clear field for a certain phase;

[0066] Step S4: triangulating the formed clear field space surface and rendering it;

[0067] Step S5: Repeat steps S3 and S4 to achieve another phase field reconstruction and rendering, and complete layer overlay.

[0068] (1) A mathematical model of the microscopic oil-water two-phase distribution was established to simulate the dynamic behavior of the oil-water two-phase in the microscopic pore structure of the core. The mass conservation and momentum conservation equations of oil and water were described by the following equations ① and ②:

[0069]

[0070]

[0071] Among them, ρ is the average density of the two phases; μ is the average density and dynamic viscosity coefficient of the two phases; u is the average velocity of the two phases; g is the gravitational acceleration, pd is the pressure, τ is the fluid stress tensor. Two-phase tracking is implemented using the fluid volume model.

[0072] Based on the finite volume method, the above mathematical model is discretized on the grid and solved iteratively to obtain the calculation results of the numerical simulation in the microscopic reservoir pore structure.

[0073] (2) Read in the result data of numerical simulation and establish a one-to-one mapping relationship between the background grid and the physical field, which is characterized by:

[0074] A mapping relationship is established between the background grid unit body number and the value of the physical quantity at the center of the background grid unit body, thereby realizing the correspondence between the grid points, grid surfaces, grid bodies and physical quantity data; finally, the mapping relationship is stored.

[0075] (3) Clearly reconstruct the oil-water interface and segment the flow field to obtain a clear field for a certain phase.

[0076] Step 1: Traverse all fluid grid cells and obtain the center points of all grid cells ( Figure 2 The solid dots in the middle) are spatial position information and stored physical quantity information.

[0077] Step 2: loop through all grid points to obtain the location information of all grid points and the neighbor relationship between grid points and grid cells; use the inverse distance weighted interpolation algorithm to map grid cell values ​​to grid point values; Figure 1 As shown, the value of the physical quantity at the grid point i1 is obtained by sharing the values ​​of the center positions of the grid cells i, j, k, l, m, and n at the grid point and performing inverse distance weighted interpolation;

[0078] Step 3: Determine the segmentation boundary of the field, loop all grid edges, and determine whether the given segmentation threshold is between the values ​​of two adjacent grid points based on the positional relationship between the grid points and the edges; if the segmentation threshold is between the two grid point values, the interface and the edge intersect, otherwise they do not intersect.

[0079] Step 4: Loop through all mesh edges that intersect with the interface, and calculate the intersection of the interface and the mesh edge by linear interpolation. For example, the position information of the intersection point h1 with the interface is obtained by the position information and physical value of i1 and j1 on the edge i1j1 mesh line.

[0080] Step 5: Connect the boundary points on the grid surface in sequence to obtain the boundary lines on the grid surface, connect the boundary lines on adjacent grid surfaces in sequence, reconstruct a clear oil-water boundary interface based on threshold segmentation, and obtain a clear phase region.

[0081] (4) Triangulate the clear field space surface (such as Figure 3As shown in the figure, the triangulated surface mesh is rendered, and the mesh surface of the clear phase space is traversed. When the external boundary surface is a convex polygon, any two non-adjacent points of the convex polygon are connected, and so on, until the polygon is divided into triangles that cannot be divided any more; when the external boundary surface is a concave polygon, the ear cutting method is used to divide it and triangulate it. The triangulated mesh surface is rendered according to specific physical quantity values.

[0082] (5) Render the triangulated surface mesh and implement multi-layer overlay

[0083] Repeat steps 3-4 to obtain two layers of phase physics fields, such as Figure 4 As shown, Figure 4 a gives the monochrome rendering result of physical field one. Figure 4 b shows the monochrome rendering result of physical field 2. The rendering result of the final physical quantity obtained by superimposing the two layers (such as Figure 4 c). Since the two physical quantities are displayed in two layers respectively, the phase interface obtained by superposition is clear.

[0084] like Figure 5 The figure shows the rock pore physical model used in the calculation, which contains multiple interconnected micron-scale pore channels. The physical model is divided into grids, and the mathematical model established in step (1) is used to solve the physical quantities on the grid units.

[0085] like Figure 6 As shown, a visualization image of the numerical simulation results of the local pore volume fraction is given. Figure 6 a is the oil-water interface obtained by the traditional method. It is found that there is an obvious transition zone at the interface between water (shown in black) and oil (shown in gray), and oil and water are difficult to distinguish in this transition zone; Figure 6 b is the clear oil-water interface obtained by the method in this paper.

[0086] like Figure 7 As shown, the method based on the present invention can further demonstrate the physical phenomenon that a certain population only exists in one phase. The figure shows the superposition rendering of three layers of black, dark gray and gray.

[0087] Beneficial effect: The present invention provides a method for visualizing a two-phase flow field with a clear interface of a numerical simulation result of water flooding in a microscopic reservoir, comprising establishing a calculation domain model of a microscopic reservoir, constructing a mathematical model of a microscopic numerical simulation of a microscopic reservoir, reconstructing the two-phase interface of the simulation result, and superimposing multiple layers to finally realize the rendering of a two-phase flow field with a clear interface.

[0088] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for visualizing the interface flow field of microscopic water flooding numerical simulation results, characterized in that: The visualization method comprises: Step S1: establishing a mathematical model and solution method for microscopic water-to-oil displacement, performing numerical simulation of the water-to-oil displacement process, and obtaining numerical simulation result data; Step S2: establishing a mapping relationship between the background grid and the physical quantity field according to the numerical simulation result data; Step S3: clearly reconstructing the oil-water two-phase interface and segmenting the flow field to obtain a clear field of the oil phase or the water phase; Step S4: performing triangulation processing and rendering according to the spatial surface of the clear field; Step S5: Repeat steps S3 and S4 to achieve another phase field reconstruction and rendering, and complete layer overlay.

2. A method for visualizing interface flow field of microscopic water flooding numerical simulation results according to claim 1, characterized in that: The step S1: establishing a mathematical model of microscopic water-to-oil displacement specifically includes: A mathematical model of microscopic oil-water two-phase distribution is established to simulate the dynamic behavior of oil-water two-phase in the microscopic pore structure of the core. The oil-water two-phase tracking is implemented by using a fluid volume model.

3. A method for visualizing interface flow field of microscopic water flooding numerical simulation results according to claim 2, characterized in that: The mass conservation and momentum conservation equations of oil and water in the mathematical model are described by the following equations ① and ②: Among them, ρ is the average density of the two phases; μ is the average density and dynamic viscosity coefficient of the two phases; u is the average velocity of the two phases; g is the gravitational acceleration, p d is the pressure and τ is the fluid stress tensor.

4. The method for visualizing the interface flow field of microscopic water flooding numerical simulation results according to claim 1, characterized in that: The numerical simulation of the water-to-oil process is performed in step S1, and the numerical simulation result data obtained specifically includes: The mathematical model is discretized on a grid based on a finite volume method, and an iterative solution is performed to obtain the calculation results of the numerical simulation in the microscopic reservoir pore structure.

5. The method for visualizing the interface flow field of microscopic water flooding numerical simulation results according to claim 1, characterized in that: The step S2: establishing a mapping relationship between a background grid and a physical quantity field according to the numerical simulation result data specifically includes: Establish a mapping relationship between the background grid unit body number and the value of the physical quantity at the center of the background grid unit body; The mapping relationship is stored.

6. A method for visualizing interface flow field of microscopic water flooding numerical simulation results according to claim 5, characterized in that: The mapping relationship specifically includes: the corresponding relationship between grid points, grid surfaces, grid bodies and physical quantity data.

7. The method for visualizing the interface flow field of microscopic water flooding numerical simulation results according to claim 1, characterized in that: The step S3: clearly reconstructing the oil-water two-phase interface and segmenting the flow field to obtain the clear field of the oil phase or the water phase specifically includes: Traverse all fluid grid cells to obtain the spatial position information of the center points of all grid cells and the stored physical quantity information; Loop through all grid points to obtain the location information of all grid points and the neighbor relationship between grid points and grid cells; Establish a mapping from grid cell values ​​to grid point values; Determine the segmentation boundary of the field, loop all grid edges, and determine whether the given segmentation threshold is between the values ​​of two adjacent grid points based on the positional relationship between the grid points and the edges; if the segmentation threshold is between the values ​​of the two grid points, the interface and the edge intersect, otherwise they do not intersect; Loop through all mesh edges that intersect the phase interface, and calculate the intersection points between the phase interface and the mesh edge by linear interpolation; The dividing points on the grid surface are connected in sequence to obtain the dividing lines on the grid surface, and the dividing lines on adjacent grid surfaces are connected in sequence to reconstruct a clear oil-water boundary interface based on threshold segmentation to obtain a clear phase region.

8. The method for visualizing the interface flow field of microscopic water flooding numerical simulation results according to claim 7, characterized in that: The establishing of the mapping from the grid cell value to the grid point value specifically includes: using an inverse distance weighted interpolation algorithm to implement the mapping from the grid cell value to the grid point value.

9. The method for visualizing the interface flow field of microscopic water flooding numerical simulation results according to claim 1, characterized in that: The step S4: performing triangulation processing and rendering according to the spatial surface of the clear field specifically includes: Traverse the mesh surface of the clear phase space. When the external boundary surface is a convex polygon, connect any two non-adjacent points of the convex polygon, and so on, until the polygon is divided into triangles that cannot be divided any more; When the external boundary surface is a concave polygon, the ear-cut method is used to perform triangulation; The triangulated mesh surface is rendered according to the set physical quantity values.

10. The method for visualizing the interface flow field of microscopic water flooding numerical simulation results according to claim 1, characterized in that: The step S5: repeating the steps S3 to S4 to realize another phase field reconstruction and rendering, and completing the layer overlay specifically includes: Repeat steps 3-4 to obtain the layer of water-oil two-phase physical field; The rendering result of the final physical quantity obtained by superimposing two layers.

11. A microscopic water flooding numerical simulation result interface flow field visualization system, using a microscopic water flooding numerical simulation result interface flow field visualization method according to any one of claims 1 to 10, characterized in that: The visualization system comprises: Model building module, used to establish the mathematical model and solution method of microscopic water-to-oil displacement, conduct numerical simulation of the water-to-oil displacement process, and obtain numerical simulation result data; A mapping relationship establishment module, used to establish a mapping relationship between a background grid and a physical quantity field according to the numerical simulation result data; A segmentation module, used for clearly reconstructing the oil-water two-phase interface and segmenting the flow field to obtain a clear field of the oil phase or the water phase; A triangulation processing module, used for performing triangulation processing and rendering according to the spatial surface of the clear field; The overlay module is used to repeat step S3-step S4 to achieve another phase field reconstruction and rendering, and complete layer overlay.

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