Fractured well single well tracer production interpretation method and system based on fluid mechanics VOF method

Abstract

The application discloses a kind of based on fluid mechanics VOF method's fractured well single well trace production interpretation method and system, the method includes the following steps: S1: using trace monitoring wellbore-matrix-fracture intelligent modeling method establishes fractured well single well reservoir model;S2: based on fluid mechanics, establish oil-gas-water three-phase percolation and tracer migration mathematical model;S3: on the fractured well single well reservoir model, the oil-gas-water three-phase percolation and tracer migration mathematical model are solved, obtain simulation production dynamic data;S4: the simulation production dynamic data are compared with tracer measured data: if both are not consistent, then adjust the fracture parameters of the fractured well single well reservoir model, repeat steps S1-S4;If both are consistent, then through the oil-gas-water three-phase percolation and tracer migration mathematical model output simulation result.The application can more accurately carry out fractured well single well trace production interpretation.

Description

Technical Field

[0001] This invention relates to the field of fracturing technology, and in particular to a single-well tracer production interpretation method and system for fracturing wells based on the fluid dynamics VOF method. Background Technology

[0002] The study of mathematical models for interpreting fracture parameters using tracers in reservoir fracturing is of great significance in oil and gas field development. Through accurate mathematical models and numerical simulation equations, reservoir engineers can better understand the geometry and conductivity of fractures, thereby optimizing fracturing design and enabling more efficient flow of oil and gas into the wellbore. Interpreting tracer flow states through mathematical models and numerical simulations allows for effective monitoring and evaluation of fracturing effectiveness. Analysis of tracer data provides detailed information on fracture parameters and distribution, enabling the assessment of the actual effectiveness of fracturing operations. This assessment is crucial for adjusting production strategies and optimizing subsequent development plans.

[0003] Current technologies primarily rely on commercial software to model reservoirs using triangular meshes and employ black oil models for numerical simulation and analysis. However, triangular mesh modeling is challenging, and the resulting data often leads to difficulties or non-convergence in subsequent production capacity calculations. While the classic black oil model in commercial software is relatively mature, the numerous nonlinear seepage and complex multiphase flow characteristics inherent in the rock cannot be replicated in commercial software, becoming a bottleneck hindering the further development of tracer production interpretation technologies. Summary of the Invention

[0004] To address the aforementioned problems, this invention aims to provide a method and system for interpreting single-well tracer production in fractured wells based on the fluid dynamics VOF method.

[0005] The technical solution of the present invention is as follows: On the one hand, a single-well tracer production interpretation method for fractured wells based on the fluid dynamics VOF method is provided, including the following steps: S1: A single-well reservoir model for fracturing wells is established using a tracer-monitoring intelligent modeling method for wellbore-matrix-fracture. S2: Establish a mathematical model of three-phase flow of oil, gas and water and tracer transport based on fluid mechanics; S3: Solve the mathematical model of three-phase flow of oil, gas and water and tracer migration on the single-well reservoir model of the fractured well to obtain simulated production dynamic data; S4: Compare the simulated production dynamic data with the tracer measured data: If the simulated production dynamic data does not match the measured data of the tracer, adjust the fracture parameters of the single-well reservoir model of the fractured well and repeat steps S1-S4. If the simulated production dynamic data matches the measured data of the tracer, the simulation results are output through the mathematical model of oil-gas-water three-phase flow and tracer migration.

[0006] Preferably, in step S1, the tracer monitoring wellbore-matrix-fracture intelligent modeling method uses an unsupervised machine learning algorithm to cluster the overall grid coordinate point data volume to obtain the coupling connection relationship between the un-densified grid and the densified grid. The overall grid coordinate point data volume and the coupling connection relationship are used as the single-well reservoir model of the fractured well corresponding to the wellbore-fracture-matrix. The overall grid coordinate point data volume is obtained by merging the wellbore grid coordinate point data volume and the matrix-fracture grid coordinate point data volume. The wellbore grid coordinate point data volume and the matrix-fracture grid coordinate point data volume are obtained by using an unsupervised machine learning algorithm to densify multiple reservoir grid points near the wellbore and fracture, respectively.

[0007] Preferably, the encryption operation is implemented using a clustering algorithm.

[0008] Preferably, in step S2, the mathematical model for the three-phase flow of oil, gas, and water and the tracer transport includes: (1) Mass conservation equation for three-phase fluids: (1) In the formula: t is time, s; V is volume, m 3 ; Porosity, dimensionless; ρ m The density of the mixed fluid, kg / m³ 3 A represents the area, in meters. 2 ; q is the average linear velocity of the mixed fluid flowing in all directions, in m / s; io For source and sink phases, it represents the mass of fluid entering or leaving the micro-element per unit time, in kg / s; (2) Momentum conservation equation for three-phase fluids of oil, gas and water: (2) In the formula: Represents the divergence operator; The pressure gradient of the mixed fluid; μ m The viscosity of the mixed fluid is Pa·s; k is the absolute permeability of the rock, mD; p c ρ is the capillary pressure at the oil-gas-water three-phase interface, MPa; l is the grid side length, m; ρ is the fluid density, kg / m³. 3 ; The acceleration vector due to gravity, in m / s² 2 ; (3) Equation for phase saturation of three-phase fluids: oil, gas and water (3) (4) (5) (6) In the formula: S oi S gi S wi These represent the saturation levels of the oil, gas, and water phases, respectively, and are dimensionless; ρ oi ρ gi ρ wi Densities of oil phase, gas phase, and water phase, respectively, in kg / m³ 3 ;R oi R gi R wi These are the adsorption coefficients of the tracers in the oil phase, gas phase, and aqueous phase, respectively. , , The velocities of the oil, gas, and water phases are respectively, in m / s; D oi D gi D wi These are the diffusion coefficients of the tracers in the oil phase, gas phase, and aqueous phase, respectively. , , These are the average phase saturations of the oil phase, gas phase, and aqueous phase, respectively, and are dimensionless. , , q represents the phase saturation gradients of the oil, gas, and aqueous phases, respectively, and is dimensionless. oi q gi q wi Source and sink terms for oil, gas, and aqueous phases, respectively, kg / s; S o S g S w These represent the phase saturation of oil, gas, and water, respectively.

[0009] Preferably, the density of the mixed fluid is calculated using the following formula: (7) In the formula: ρ o ρ w ρ g The densities of the oil phase, water phase, and gas phase are respectively, in kg / m³. 3 .

[0010] Preferably, the viscosity of the mixed fluid is calculated using the following formula: (8) Where: μ w μ g μ oThe values ​​are the viscosities of the aqueous phase, gas phase, and oil phase, respectively, in Pa·s.

[0011] Preferably, the capillary pressure at the oil-gas-water three-phase interface is calculated using the following formula: (9) In the formula: σ wg The interfacial tension between air and water, N / m; θ wg θ is the wetting contact angle between the air-water interface and the rock surface, in °; r is the average pore throat radius of the rock, in m; σ is a dimensionless function of gas-water saturation; ow The interfacial tension between oil and water is N / m; θ ow The wetting contact angle between the oil-water interface and the rock surface is expressed in °. This is a dimensionless function of oil-water saturation.

[0012] Preferably, in step S3, the mathematical model of the three-phase flow of oil, gas and water and tracer transport is solved numerically by discretization.

[0013] As a preferred method, the finite volume method is used for discretization.

[0014] On the other hand, a single-well tracer production interpretation system for fractured wells based on the fluid dynamics VOF method is also provided, including: The single-well reservoir model module for fractured wells is used to establish a single-well reservoir model for fractured wells by employing a tracer monitoring method for intelligent modeling of the wellbore-matrix-fracture. The module for mathematical models of three-phase flow and tracer transport in oil, gas and water is used to establish mathematical models of three-phase flow and tracer transport in oil, gas and water based on fluid mechanics. The solution module is used to solve the mathematical model of the three-phase flow of oil, gas and water and tracer migration on the single-well reservoir model of the fractured well to obtain simulated production dynamic data. The data comparison and output module is used to compare the simulated production dynamic data with the tracer measured data. If the simulated production dynamic data does not match the measured data of the tracer, the fracture parameters of the single-well reservoir model of the fractured well shall be adjusted. If the simulated production dynamic data matches the measured data of the tracer, the simulation results are output through the mathematical model of oil-gas-water three-phase flow and tracer migration.

[0015] The beneficial effects of this invention are: This invention establishes a single-well reservoir model for fractured wells by employing a tracer-monitoring intelligent modeling method for wellbore-matrix-fracture. This method can establish a more refined geological property model and improve the accuracy of subsequent mathematical modeling of oil, gas, and water three-phase flow and tracer migration. By establishing a mathematical model of oil, gas, and water three-phase flow and tracer migration based on fluid mechanics, which takes into account tracer migration, it can more accurately interpret the tracer production of fractured wells. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the process for interpreting single-well tracer production in fractured wells based on the fluid dynamics VOF method of the present invention. Figure 2 This is a schematic diagram of a single-well reservoir model for a fractured vertical well in a specific embodiment; Figure 3 This is a schematic diagram of a single-well reservoir model for a fractured horizontal well in a specific embodiment; Figure 4 This is a schematic diagram comparing the simulated results of the initial crack parameters with the measured data (total output) in a specific embodiment; Figure 5 This is a schematic diagram showing the comparison between the simulation results of the initial crack parameters and the measured data (Level 1) in a specific embodiment; Figure 6 This is a schematic diagram comparing the simulated results of the initial crack parameters with the measured data (level 2) in a specific embodiment; Figure 7 This is a schematic diagram comparing the simulated results of the initial crack parameters with the measured data (level 3) in a specific embodiment; Figure 8 This is a schematic diagram comparing the simulated results of the initial crack parameters with the measured data (level 4) in a specific embodiment; Figure 9 This is a schematic diagram showing the comparison between the simulated results of the initial crack parameters and the measured data (level 5) in a specific embodiment; Figure 10 This is a schematic diagram showing the comparison between the final simulation results and the measured data (total output) in a specific embodiment; Figure 11 This is a schematic diagram showing the comparison between the final simulation results and the measured data (Level 1) in a specific embodiment; Figure 12 This is a schematic diagram showing the comparison between the final simulation results and the measured data (Level 2) in a specific embodiment; Figure 13 This is a schematic diagram showing the comparison between the final simulation results and the measured data (Level 3) in a specific embodiment; Figure 14 This is a schematic diagram showing the comparison between the final simulation results and the measured data (Level 4) in a specific embodiment; Figure 15 This is a schematic diagram showing the comparison between the final simulation results and the measured data (Level 5) in a specific embodiment. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and technical features described in this application can be combined with each other. It should also be pointed out that, unless otherwise indicated, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms "comprising" or "including" and similar words used in this invention refer to elements or objects preceding the word that encompass the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0019] On the one hand, this invention provides a single-well tracer production interpretation method for fractured wells based on the fluid dynamics VOF method, including the following steps: S1: A single-well reservoir model for fracturing wells is established using a tracer-monitoring intelligent modeling method for wellbore-matrix-fracture.

[0020] In a specific embodiment, the tracer monitoring wellbore-matrix-fracture intelligent modeling method utilizes an unsupervised machine learning algorithm to cluster the overall grid coordinate point data volume to obtain the coupling connection relationship between unrefined and refined grids. The overall grid coordinate point data volume and the coupling connection relationship serve as the single-well reservoir model for the fractured well corresponding to the wellbore-fracture-matrix region. The overall grid coordinate point data volume is obtained by merging the wellbore grid coordinate point data volume and the matrix-fracture grid coordinate point data volume. The wellbore grid coordinate point data volume and the matrix-fracture grid coordinate point data volume are respectively obtained by refining multiple reservoir grid points near the wellbore and fracture using an unsupervised machine learning algorithm. Optionally, the refining operation is implemented using a clustering algorithm.

[0021] In a specific embodiment, step S1 specifically includes the following sub-steps: (1) Data collection, including: ① Basic parameters: coarse grid size l 粗 Fine mesh size l 细① Formation temperature, original formation pressure, viscosity and density of formation oil and water, apparent molecular weight of gas, injection and production time, etc.; ② Well trajectory data: drilling depth d 1i Actual vertical depth z i East-west biased towards x i North-South y i ③ Well logging interpretation data: Well logging depth d 2i Porosity Φ i Penetration rate k i Water saturation S wi ④ PETREL reservoir geological data: Obtain the PETREL geological modeling data body for the current work area. The data body file format is .GRDECL. The data body contains geological data such as porosity, permeability, and formation coordinates of the reservoir in the current work area. The subscript i in the above data body indicates that there are multiple data points and they are stored in the computer in the form of a list. ⑤ Single well tracer production measurement data.

[0022] (2) Well trajectory data processing: Establishing drilling depth d 1i and actual vertical depth z i The one-dimensional linear interpolation function relationship F between them z , i.e. z i =F z (d 1i The F function can be represented by the linear function y = ax + b; establish the drilling depth d. 1i And the things lean towards x i The one-dimensional linear interpolation function relationship F between them x , that is, x i =F x (d 1i Establish drilling depth d 1i and north-south bias y i The one-dimensional linear interpolation function relationship F between them y , that is, y i =F y (d 1i The one-dimensional linear interpolation function can be implemented using the `interp1d` function provided by the `interpolate` module in Python / SciPy. Based on the above three linear interpolation function relationships for well trajectories, the complete well trajectory (x) in the reservoir can be calculated by interpolation. 1i y 1i , z 1i Coordinate values.

[0023] (3) Well logging data processing: Since the well logging data only has one well logging depth value d 2i Substituting this value into the linear interpolation function of the three well trajectories allows us to calculate the three-dimensional (x, y) of the logging data points in the reservoir. 2i y2i , z 2i Coordinates. At this point, the logging depth value d needs to be input. 2i , that is, x 2i =F x (d 2i ) ;y 2i =F y (d 2i ) ;z 2i =F z (d 2i The above calculation results, combined with the original logging data, yield a complete logging data volume for subsequent modeling: the logging point (x...). 2i y 2i , z 2i Coordinate values, porosity Φ i Penetration rate k i Water saturation S wi .

[0024] (4) PETREL Reservoir Geological Data Preprocessing: Export the reservoir geological data volume file (.GRDECL) of the study area from the PETREL software, and use the Python module PyGRDECL to convert the reservoir geological data volume file (.GRDECL) into a VTK data volume file (e.g., .vtu). It should be noted that both .GRDECL and .vtu file formats use corner coordinates for grid data construction, with one hexahedral grid containing 8 vertices (p1, p2, p3, p4, p5, p6, p7, p8). i =(x i ,y i ,z i The center coordinates p of all grid cells can be calculated from the coordinates of the 8 vertices. ci :p ci =1 / 8×(p1+ p2+ p3+ p4+ p5+ p6+ p7+ p8). In the processed data volume, the coordinates of the center point p of the grid are... ci (x) i y i , z i Porosity Φ i Penetration rate k i It is a one-to-one correspondence, meaning that for each center point coordinate, there is a corresponding porosity and a permeability value.

[0025] (5) Establishing a discrete grid model of the reservoir: Based on the logging points (x) of the logging data volume obtained by processing logging data. 2i y 2i , z 2iBy determining the maximum and minimum values ​​of the XYZ three-dimensional coordinates, the maximum three-dimensional XYZ length (L) of the reservoir can be calculated. x L y L z ):L x = max(x i ) - min(x i );L y = max(y i ) - min(y i );L z = max(z i ) - min(z i Set the side length of the coarse mesh to l. 粗 Then the number of XYZ grids (n) is obtained. x n y n z ) is: n x = L x / l 粗 ;n y = L y / l 粗 ;n z = L z / l 粗 Based on the above data, a grid system can be established, and the coordinates of the center point of each grid cell can be calculated: x 4i = x0 + 0.5l + il;y 4i = y0 + 0.5l + jl; z 4i = z0 + 0.5l + kl; where i, j, and k are the numbers of each grid in the three-dimensional block grid system in the XYZ directions, and (x0, y0, z0) are the coordinates of the grid's starting point.

[0026] (6) Modeling of hydraulic fracturing fractures Collect fracturing data for the study section: fracturing section depth d 3i The east half of the crack f xi Crack height f yi Main fracture permeability k fi Permeability k in the fracture zone SRVi The depth of the fracturing section is determined using well logging depth values, and the fracturing section depth d is... 3i By substituting the values ​​into the linear interpolation functions of the three well trajectories, the three-dimensional (x, y) coordinates of the fracturing fracture initiation point in the reservoir can be calculated. 3i y 3i , z 3i ) coordinates, i.e., x 3i =F x (d 3i ), y3i =F y (d 3i ), z 3i =Fz(d 3i ).

[0027] In engineering practice, it is generally assumed that the main fracture surface of the fracturing system is perpendicular to the well trajectory and perpendicular to the horizontal plane. Therefore, the normal vector of the main fracture surface can be calculated based on the two-dimensional (x, y) coordinates of the well trajectory's starting and ending points. Let the well trajectory's starting point P1 = (x1, y1, 1) and ending point P1 = (x2, y2, 1) be set, then the direction vector can be expressed as: (10) Its length L can be calculated using the following formula: (11) Final normal vector This can be represented as the direction vector divided by the length: (12) Combining the above calculation results with the original fracturing fracture data yields a complete fracturing fracture data volume for subsequent modeling: the fracturing fracture initiation point (x... 3i y 3i , z 3i The coordinate values ​​are the normal vectors centered at the crack initiation point. The east half of the crack f xi Crack height f yi Main fracture permeability k fi Permeability k in the fracture zone SRVi .

[0028] (7) Multi-scale intensified modeling of wellbore-matrix-fracturing fractures ① Intensive modeling near the wellbore: Based on the unsupervised machine learning KNN algorithm, all reservoir grid coordinates (x, y, y) obtained in the above steps are used to refine the model. 4i y 4i , z 4i The data points are imported into the KNN model, using the complete wellbore (well trajectory) coordinate data (x) obtained from the well trajectory data processing in step (2). 1i y 1i , z 1i The search point set is defined by K, which can be set to a range of 10-50. The search results are the coordinates of the 10-50 grid points closest to all wellbore points, including the wellbore points themselves. The selected grid is then refined. The specific steps are as follows: 1) Excavation. Excavate the selected reservoir grid points and delete their corresponding grid numbers and coordinate values ​​(x, y, y). 4i y 4i , z4i ); 2) Fill. Based on the side length of the selected mesh and the mesh size parameters to be refined (e.g., side length l)... 细 ), calculate the coordinates of the starting point of the local mesh and the center point of all refined meshes; 3) Merging. The original coarse grid coordinate point data volume is merged with the fine grid coordinate point data volume (i.e., the center point coordinates of all refined grids) to obtain a new grid coordinate point data volume (x). 4i ',y 4i ',z 4i '); ② Matrix-fracturing fracture refinement modeling: fracturing initiation point coordinate data (x 3i y 3i , z 3i Combined with normal vector The east half of the crack f xi and crack height f yi Calculate the extent of the crack extension (using the Boolean function): (13) Based on the unsupervised machine learning KNN algorithm, the coordinates of all obtained reservoir grids (x 4i y 4i , z 4i Importing data points into the KNN model, using Boolean... i ×(x 4i y 4i , z 4i The data volume corresponds to the search points. The K value can be set to a range of 10-50. The search results are the coordinates of the 10-50 grid points closest to all fracturing fractures, including the fracturing fractures and the matrix SRV region. The selected grid is then refined. The specific steps are as follows: 1) Excavation. Excavate the selected reservoir grid points and delete their corresponding grid numbers and coordinate values ​​(x, y, y). 4i y 4i , z 4i ); 2) Fill. Based on the side length of the selected mesh and the mesh size parameters to be refined (e.g., side length l)... 细 ), calculate the coordinates of the starting point of the local mesh and the center point of all refined meshes; 3) Merge. Merge the coarse grid coordinate point data volume with the fine grid coordinate point data volume to obtain a new grid coordinate point data volume (x). 4i ',y 4i ',z 4i ').

[0029] ③ Multi-scale grid coupling relationship modeling: Based on the unsupervised machine learning KNN algorithm, the new reservoir grid coordinate data volume (x) obtained in the above steps is used to model the relationship between the grid coupling relationship and the network structure. 4i ',y 4i ',z 4i Import the data into the KNN model, using the data volume (x) 4i ',y 4i ',z 4i The search point itself is set as the K value, which is set to a range of 5 to 10. The search results yield the coupling connection relationship of all coarse and fine grids. The overall grid coordinate point data volume and the coupling connection relationship are the reservoir model corresponding to the wellbore-fracture-matrix.

[0030] It should be noted that the aforementioned intelligent modeling method for tracer monitoring wellbore-matrix-fracture is existing technology. For other matters not covered, please refer to the technical solution disclosed in CN119740374A "An Intelligent Modeling Method and System for Tracer Monitoring Wellbore-Matrix-Fractured Fracture".

[0031] S2: Establish a mathematical model of three-phase flow of oil, gas and water and tracer transport based on fluid mechanics.

[0032] In one specific embodiment, the mathematical model for the three-phase flow of oil, gas, and water and tracer transport includes: (1) Mass conservation equation for three-phase fluids: (1) In the formula: t is time, s; V is volume, m 3 ; Porosity, dimensionless; ρ m The density of the mixed fluid, kg / m³ 3 A represents the area, in meters. 2 ; q is the average linear velocity of the mixed fluid flowing in all directions, in m / s; io For source and sink phases, it represents the mass of fluid entering or leaving the micro-element per unit time, in kg / s; (2) Momentum conservation equation for three-phase fluids of oil, gas and water: (2) In the formula: Represents the divergence operator; The pressure gradient of the mixed fluid; μ m The viscosity of the mixed fluid is Pa·s; k is the absolute permeability of the rock, mD; p c ρ is the capillary pressure at the oil-gas-water three-phase interface, MPa; l is the grid side length, m; ρ is the fluid density, kg / m³. 3 ; The acceleration vector due to gravity, in m / s² 2 ; (3) Equation for phase saturation of three-phase fluids: oil, gas and water (3) (4) (5) (6) In the formula: S oi S gi S wi These represent the saturation levels of the oil, gas, and water phases, respectively, and are dimensionless; ρ oi ρ gi ρ wi Densities of oil phase, gas phase, and water phase, respectively, in kg / m³ 3 ;R oi R gi R wi These are the adsorption coefficients of the tracers in the oil phase, gas phase, and aqueous phase, respectively. , , The velocities of the oil, gas, and water phases are respectively, in m / s; D oi D gi D wi These are the diffusion coefficients of the tracers in the oil phase, gas phase, and aqueous phase, respectively. , , These are the average phase saturations of the oil phase, gas phase, and aqueous phase, respectively, and are dimensionless. , , q represents the phase saturation gradients of the oil, gas, and aqueous phases, respectively, and is dimensionless. oi q gi q wi Source and sink terms for oil, gas, and aqueous phases, respectively, kg / s; S o S g S w These represent the phase saturation of oil, gas, and water, respectively.

[0033] In the above embodiments, the derivation of the mathematical model for the three-phase flow of oil, gas, and water and tracer transport is as follows: The seepage process of oil, gas and water three-phase fluids in rocks also satisfies the mass conservation equation. According to the fact that the net inflow mass flux into the control surface of the micro-element per unit time is equal to the increase in fluid mass of the micro-element per unit time, the formula for the increase in oil, gas and water mass per unit time can be obtained, thus obtaining the mass conservation equation of oil, gas and water three-phase fluids shown in equation (1).

[0034] For the momentum conservation equation of a three-phase fluid consisting of oil, gas, and water, the capillary pressure p caused by the oil-gas-water interface needs to be considered. cThe gravity effect caused by the density difference between oil, gas and water. At the same time, since there are differences in density and viscosity between different components of the three-phase oil-gas-water or oil-gas-water mixture, in order to more accurately simulate and predict the behavior of these complex fluid systems, the concepts of mixed density (referring to the overall average density after considering the density difference between different components) and mixed viscosity (referring to the overall average viscosity after considering the viscosity difference between different components) are introduced into the momentum conservation equation of the three-phase oil-gas-water fluid. Combined with the momentum conservation equation of fluid flow, the momentum conservation equation of the three-phase oil-gas-water fluid shown in equation (2) is obtained.

[0035] For three-phase flow of oil, gas, and water, the phase saturation equation also needs to be considered to solve for the volume fraction of each component. The above-mentioned mass conservation equation, momentum conservation equation, and phase saturation equation for three-phase flow of oil, gas, and water constitute the mathematical model of three-phase flow of oil, gas, and water and tracer transport.

[0036] In one specific embodiment, the density of the mixed fluid is calculated using the following formula: (7) In the formula: ρ o ρ w ρ g The densities of the oil phase, water phase, and gas phase are respectively, in kg / m³. 3 .

[0037] In one specific embodiment, the viscosity of the mixed fluid is calculated using the following formula: (8) Where: μ w μ g μ o The values ​​are the viscosities of the aqueous phase, gas phase, and oil phase, respectively, in Pa·s.

[0038] In a specific embodiment, the capillary pressure at the oil-gas-water three-phase interface is calculated using the following formula: (9) Where: σ wg The interfacial tension between air and water, N / m; θ wg θ is the wetting contact angle between the air-water interface and the rock surface, in °; r is the average pore throat radius of the rock, in m; σ is a dimensionless function of gas-water saturation; ow The interfacial tension between oil and water is N / m; θ ow The wetting contact angle between the oil-water interface and the rock surface is expressed in °. This is a dimensionless function of oil-water saturation.

[0039] In the three-phase flow process of oil, gas, and water, the core is wet. When the injected phase is wet water, the capillary force acts as the driving force; when the injected phase is non-wet gas, the capillary pressure acts as the resistance. By combining the saturation of the three phases of oil, gas, and water with the capillary pressure, phase interface tracking can be accurately achieved.

[0040] S3: On the single-well reservoir model of the fractured well, solve the mathematical model of the three-phase flow of oil, gas and water and tracer migration to obtain simulated production dynamic data.

[0041] In one specific embodiment, the mathematical model of the three-phase flow of oil, gas, and water with tracer transport is numerically discretized during the solution process. Optionally, the finite volume method is used for discretization.

[0042] In a specific embodiment, the mathematical model of the three-phase flow of oil, gas, and water and tracer transport is numerically discretized using the finite volume method. The three-phase fluids are compressible, and the relationship between their density ρ and pressure p satisfies the following: (14) In the formula: ρ w0 ρ g0 ρ o0 The initial densities of water, gas, and oil are respectively, in kg / m³. 3 Its value will be updated to the new initial value in the next iteration; C w C g C o The compressibility coefficients (Pa) of water, gas, and oil, respectively. -1 p0 is the initial pressure, in Pa.

[0043] Within a reasonable range while ensuring accuracy, expanding using the Maclaurin series and taking the first two terms yields: (15) In the formula: ρ0 is the density of any phase under the reference pressure, kg / m³ 3 C ρ Let Pa be the compressibility coefficient of an arbitrary phase fluid. 1 ; The first term of the mass conservation equation can be written as: (16) Discretizing the time term of the mass conservation equation yields: (17) In the formula: the superscript t represents the current time, and the superscript t+Δt represents the next time, both in seconds; For the second term of the mass conservation equation This requires time-difference based on the phase equation to obtain the seepage equations for each phase of oil, gas, and water, thereby calculating the saturation of each phase in the grid: (18) In the formula: , and , respectively, represent the saturation levels of oil, gas, and water at the next instant, dimensionless; , and These are the source and sink terms for oil, gas, and water, respectively, in kg / s; , and The densities of oil, gas, and water at the next instant, respectively, in kg / m³. 3 ; , and Δt represents the velocity of oil, gas, and water at the next instant, in m / s; Δt is the time step. , and The densities of oil, gas, and water at the current moment, in kg / m³. 3 ; , and These are the current saturation levels of oil, gas, and water, respectively, and are dimensionless. Porosity at the next time step, dimensionless; The momentum conservation equation can be expressed as follows: (19) Multiply both sides by We can obtain: (20) Can be calculated : (twenty one) We can obtain: (twenty two) Where: G m The conductivity between adjacent grids i and j can be written as G. ij , represented as: (twenty three) The second term of the mass conservation equation can be expressed as follows: (twenty four) In the formula: i is the center grid number; j is the number adjacent to center grid i; z c The number of adjacent grid cells; It is the pressure, Pa, at the next moment for grid i; It is the pressure Pa at the next moment of grid j.

[0044] By simultaneously solving the discrete forms of the mass conservation equation and the momentum conservation equation, we can obtain: (25) make The overall compressibility factor is expressed in MPa. -1 The mathematical model of gas-water two-phase flow between adjacent grids after difference is obtained: (26) Any grid i is interconnected with its six neighboring grids, and the three-phase flow of oil, gas, and water between any two adjacent grids satisfies the mass conservation equation. This equation needs to be calculated once for all grids at each time step Δt.

[0045] S4: Compare the simulated production dynamic data with the tracer measured data: If the simulated production dynamic data does not match the measured data of the tracer, adjust the fracture parameters of the single-well reservoir model of the fractured well and repeat steps S1-S4. If the simulated production dynamic data matches the measured data of the tracer, the simulation results are output through the mathematical model of oil-gas-water three-phase flow and tracer migration.

[0046] It should be noted that the determination of whether two sets of data are consistent is mainly based on whether the difference between them is less than a threshold. If the difference or error between the two sets of data is less than the threshold, then the two sets of data are considered consistent; otherwise, they are not consistent.

[0047] On the other hand, the present invention also provides a single-well tracer production interpretation system for fractured wells based on the fluid dynamics VOF method, comprising: The single-well reservoir model module for fractured wells is used to establish a single-well reservoir model for fractured wells by employing a tracer monitoring method for intelligent modeling of the wellbore-matrix-fracture. The module for mathematical models of three-phase flow and tracer transport in oil, gas and water is used to establish mathematical models of three-phase flow and tracer transport in oil, gas and water based on fluid mechanics. The solution module is used to solve the mathematical model of the three-phase flow of oil, gas and water and tracer migration on the single-well reservoir model of the fractured well to obtain simulated production dynamic data. The data comparison and output module is used to compare the simulated production dynamic data with the tracer measured data. If the simulated production dynamic data does not match the measured data of the tracer, the fracture parameters of the single-well reservoir model of the fractured well shall be adjusted. If the simulated production dynamic data matches the measured data of the tracer, the simulation results are output through the mathematical model of oil-gas-water three-phase flow and tracer migration.

[0048] In a specific embodiment, taking a certain reservoir as an example, the single-well tracer production interpretation method for fractured wells based on the fluid dynamics VOF method described in this invention is used to interpret the single-well tracer production data of the fractured wells in this reservoir. In this embodiment, the interpretation process is as follows: Figure 1 As shown, based on the tracer monitoring wellbore-matrix-fracture intelligent modeling method, reservoir, fluid, and fracturing data are collected and organized to obtain a complete modeling basic data volume. The resulting fracturing vertical well single-well reservoir model is then established. Figure 2 As shown, the obtained single-well reservoir model of the fractured horizontal well is established as follows: Figure 3 As shown.

[0049] Based on experience, initial fracture parameters were set, and the simulation results of the three-phase flow of oil, gas, and water and tracer migration were obtained using the mathematical model. The results for horizontal wells are shown below. Figures 4-9 As shown in the figure. Based on the difference between the measured data and the simulation results, the crack parameters were adjusted and the simulation was repeated. After several adjustments, the simulation results finally basically matched the measured data, as shown in the figure. Figures 10-15 As shown in Table 1. Furthermore, this embodiment also compares and verifies the input crack parameters with crack detection data such as microseismic data, and the results are shown in Table 1: Table 1. Comparison of simulated crack parameters and microseismic monitoring crack parameters according to the present invention.

[0050] As can be seen from Table 1, the highest error of the crack parameter prediction results of the present invention is only 6.25%, and the average error is only 3.35%, which is less than 5%. The present invention can accurately predict crack parameters.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A single-well tracer production interpretation method for fractured wells based on the fluid dynamics VOF method, characterized in that, Includes the following steps: S1: A single-well reservoir model for fracturing wells is established using a tracer-monitoring intelligent modeling method for wellbore-matrix-fracture. In the aforementioned intelligent modeling method for tracking and monitoring wellbore-matrix-fracture, an unsupervised machine learning algorithm is used to cluster the overall grid coordinate point data volume to obtain the coupling connection relationship between unrefined and refined grids. The overall grid coordinate point data volume and the coupling connection relationship are used as the single-well reservoir model of the fractured well corresponding to the wellbore-fracture-matrix. The overall grid coordinate point data volume is obtained by merging the wellbore grid coordinate point data volume and the matrix-fracture grid coordinate point data volume. The wellbore grid coordinate point data volume and the matrix-fracture grid coordinate point data volume are obtained by refining multiple reservoir grid points near the wellbore and fracture using an unsupervised machine learning algorithm. S2: A mathematical model of three-phase flow of oil, gas, and water and tracer transport is established based on fluid mechanics; the mathematical model of three-phase flow of oil, gas, and water and tracer transport includes: (1) Mass conservation equation for three-phase fluids: （1） In the formula: t is time, s; V is volume, m 3 ; Porosity, dimensionless; ρ m The density of the mixed fluid, kg / m³ 3 A represents the area, in meters. 2 ; q is the average linear velocity of the mixed fluid flowing in all directions, in m / s; io For source and sink phases, it represents the mass of fluid entering or leaving the micro-element per unit time, in kg / s; (2) Momentum conservation equation for three-phase fluids of oil, gas and water: （2） In the formula: Represents the divergence operator; The pressure gradient of the mixed fluid; μ m The viscosity of the mixed fluid is Pa·s; k is the absolute permeability of the rock, mD; p c ρ is the capillary pressure at the oil-gas-water three-phase interface, MPa; l is the grid side length, m; ρ is the fluid density, kg / m³. 3 ; The acceleration vector due to gravity, in m / s² 2 ; (3) Equation for phase saturation of three-phase fluids: oil, gas and water （3） （4） （5） （6） In the formula: S oi S gi S wi These are the saturations of the oil phase, gas phase, and water phase, respectively, and are dimensionless. ρ oi ρ gi ρ wi Densities of oil phase, gas phase, and water phase, respectively, in kg / m³ 3 ;R oi R gi R wi These are the adsorption coefficients of the tracers in the oil phase, gas phase, and aqueous phase, respectively. , , The velocities of the oil, gas, and water phases are respectively, in m / s; D oi D gi D wi These are the diffusion coefficients of the tracers in the oil phase, gas phase, and aqueous phase, respectively. , , These are the average phase saturations of the oil phase, gas phase, and aqueous phase, respectively, and are dimensionless. , , q represents the phase saturation gradients of the oil, gas, and aqueous phases, respectively, and is dimensionless. oi q gi q wi Source and sink terms for oil, gas, and aqueous phases, respectively, kg / s; S o S g S w These represent the phase saturation of oil, gas, and water, respectively. S3: Solve the mathematical model of three-phase flow of oil, gas and water and tracer migration on the single-well reservoir model of the fractured well to obtain simulated production dynamic data; S4: Compare the simulated production dynamic data with the tracer measured data: If the simulated production dynamic data does not match the measured data of the tracer, adjust the fracture parameters of the single-well reservoir model of the fractured well and repeat steps S1-S4. If the simulated production dynamic data matches the measured data of the tracer, the simulation results are output through the mathematical model of oil-gas-water three-phase flow and tracer migration.

2. The single-well tracer production interpretation method for fractured wells based on the fluid dynamics VOF method according to claim 1, characterized in that, The encryption operation is implemented using a clustering algorithm.

3. The single-well tracer production interpretation method for fractured wells based on the fluid dynamics VOF method according to claim 1, characterized in that, The density of the mixed fluid is calculated using the following formula: （7） In the formula: ρ o ρ w ρ g The densities of the oil phase, water phase, and gas phase are respectively, in kg / m³. 3 .

4. The single-well tracer production interpretation method for fractured wells based on the fluid dynamics VOF method according to claim 1, characterized in that, The viscosity of the mixed fluid is calculated using the following formula: （8） Where: μ w μ g μ o The values ​​are the viscosities of the aqueous phase, gas phase, and oil phase, respectively, in Pa·s.

5. The single-well tracer production interpretation method for fractured wells based on the fluid dynamics VOF method according to claim 1, characterized in that, The capillary pressure at the oil-gas-water three-phase interface is calculated using the following formula: （9） Where: σ wg The interfacial tension between air and water, N / m; θ wg θ is the wetting contact angle between the air-water interface and the rock surface, in °; r is the average pore throat radius of the rock, in m; This is a dimensionless function of air-water saturation. σ ow The interfacial tension between oil and water is N / m; θ ow The wetting contact angle between the oil-water interface and the rock surface is expressed in °. This is a dimensionless function of oil-water saturation.

6. The single-well tracer production interpretation method for fractured wells based on the fluid dynamics VOF method according to claim 1, characterized in that, In step S3, the mathematical model of the three-phase flow of oil, gas and water and tracer transport is numerically discretized and solved.

7. The single-well tracer production interpretation method for fractured wells based on the fluid dynamics VOF method according to claim 6, characterized in that, Discretization is performed using the finite volume method.

8. A single-well tracer production interpretation system for fractured wells based on the fluid dynamics VOF method, characterized in that, include: The single-well reservoir model module for fractured wells is used to establish a single-well reservoir model for fractured wells by employing a tracer monitoring method for intelligent modeling of the wellbore-matrix-fracture. In the aforementioned intelligent modeling method for tracking and monitoring wellbore-matrix-fracture, an unsupervised machine learning algorithm is used to cluster the overall grid coordinate point data volume to obtain the coupling connection relationship between unrefined and refined grids. The overall grid coordinate point data volume and the coupling connection relationship are used as the single-well reservoir model of the fractured well corresponding to the wellbore-fracture-matrix. The overall grid coordinate point data volume is obtained by merging the wellbore grid coordinate point data volume and the matrix-fracture grid coordinate point data volume. The wellbore grid coordinate point data volume and the matrix-fracture grid coordinate point data volume are obtained by refining multiple reservoir grid points near the wellbore and fracture using an unsupervised machine learning algorithm. A mathematical model module for three-phase flow of oil, gas, and water and tracer transport is used to establish a mathematical model for three-phase flow of oil, gas, and water and tracer transport based on fluid mechanics; the mathematical model for three-phase flow of oil, gas, and water and tracer transport includes: (1) Mass conservation equation for three-phase fluids: （1） In the formula: t is time, s; V is volume, m 3 ; Porosity, dimensionless; ρ m The density of the mixed fluid, kg / m³ 3 A represents the area, in meters. 2 ; q is the average linear velocity of the mixed fluid flowing in all directions, in m / s; io For source and sink phases, it represents the mass of fluid entering or leaving the micro-element per unit time, in kg / s; (2) Momentum conservation equation for three-phase fluids of oil, gas and water: （2） In the formula: Represents the divergence operator; The pressure gradient of the mixed fluid; μ m The viscosity of the mixed fluid is Pa·s; k is the absolute permeability of the rock, mD; p c ρ is the capillary pressure at the oil-gas-water three-phase interface, MPa; l is the grid side length, m; ρ is the fluid density, kg / m³. 3 ; The acceleration vector due to gravity, in m / s² 2 ; (3) Equation for phase saturation of three-phase fluids: oil, gas and water （3） （4） （5） （6） In the formula: S oi S gi S wi These are the saturations of the oil phase, gas phase, and water phase, respectively, and are dimensionless. ρ oi ρ gi ρ wi Densities of oil phase, gas phase, and water phase, respectively, in kg / m³ 3 ;R oi R gi R wi These are the adsorption coefficients of the tracers in the oil phase, gas phase, and aqueous phase, respectively. , , The velocities of the oil, gas, and water phases are respectively, in m / s; D oi D gi D wi These are the diffusion coefficients of the tracers in the oil phase, gas phase, and aqueous phase, respectively. , , These are the average phase saturations of the oil phase, gas phase, and aqueous phase, respectively, and are dimensionless. , , q represents the phase saturation gradients of the oil, gas, and aqueous phases, respectively, and is dimensionless. oi q gi q wi Source and sink terms for oil, gas, and aqueous phases, respectively, kg / s; S o S g S w These represent the phase saturation of oil, gas, and water, respectively. The solution module is used to solve the mathematical model of the three-phase flow of oil, gas and water and tracer migration on the single-well reservoir model of the fractured well to obtain simulated production dynamic data. The data comparison and output module is used to compare the simulated production dynamic data with the tracer measured data. If the simulated production dynamic data does not match the measured data of the tracer, the fracture parameters of the single-well reservoir model of the fractured well shall be adjusted. If the simulated production dynamic data matches the measured data of the tracer, the simulation results are output through the mathematical model of oil-gas-water three-phase flow and tracer migration.

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