CN105913494A - Multi-scale fracture fine geological modeling and value simulation method and device - Google Patents

Abstract

The invention discloses a multi-scale fracture fine geological modeling and numerical simulation method and device, belonging to the technical field of oil reservoir numerical simulation. The method includes: acquiring corner grid and fracture network data; classifying and screening fractures; generating unstructured basic grid and unstructured numerical simulation grid, and performing corner grid matrix property mapping; class III fractures Equivalent to the basic grid, and further equivalent to the numerical simulation grid; use the global coarsening technique to calculate all conductivities of the final numerical simulation grid. The invention can process cracks with different properties in a targeted manner, thereby reducing the number of numerical simulation grids and increasing the calculation speed of numerical simulation under the premise of ensuring the accuracy of numerical simulation.

Description

Multi-scale fracture fine geological modeling and numerical simulation method and device

technical field

The invention relates to the technical field of reservoir description and reservoir numerical simulation, in particular to a multi-scale fracture fine geological modeling and numerical simulation method and device.

Background technique

Fractured reservoirs are a widely existing type of reservoirs. According to incomplete statistics, fractured reservoirs account for more than 28% of the proven geological reserves. The modeling and numerical modeling of fractured reservoirs has always been a major difficulty in the industry, mainly reflected in the huge differences in scale, seepage conductivity and other flow characteristics between matrix and fractures of different levels.

Aiming at the characteristics of fractures, there are mainly two methods of dual-media model and discrete fracture model to describe fractures, and provide models and parameters for subsequent numerical simulations. These two models have different characteristics and adaptability: the dual-media model has the advantage of being stable and efficient, but its accuracy is low, and it is often only suitable for areas with developed medium and small fractures, and is not suitable for large-scale fractures that have a major impact on the flow of the entire reservoir. The discrete fracture model is characterized by fine fracture description and high numerical simulation accuracy. However, due to its extremely high resolution, it cannot efficiently simulate reservoirs with medium and small fractures. Figure 1 shows a schematic diagram of a fractured reservoir (left), and its corresponding dual-media model (middle) and discrete fracture model (right).

However, since fractured reservoirs usually have fractures of different origins, scales and distribution patterns, the above two models cannot meet the requirements of accuracy and efficiency at the same time. Therefore, it is necessary to develop a new model for multi-scale fractured reservoirs. Modular and numerical simulation techniques.

Due to the existence of small-scale fractures, for the modeling and numerical simulation of multi-scale fractured reservoirs, dual-media models are still mostly used at home and abroad. That is, without distinguishing the scale or flow characteristics of fractures, the numerical simulation model parameters are calculated uniformly for the fracture system of the whole reservoir by a specific method: fracture porosity and permeability, and the channeling coefficient between matrix and fracture grid, Also known as form factor.

Among them, there are many ways to calculate the parameters of the dual-media model, including the traditional calculation method based on fracture geometry statistics, the calculation method based on local flow calculation, and a flow-based upscaling method that has become more popular in recent years. No matter which method is adopted, there are inevitably limitations of the dual-media model. For example, the flow coarsening method can obtain a high-accuracy dual-media model when fractures are relatively developed or distributed in a network pattern, but in areas where fractures are scattered or some large fractures play a dominant role, it may cause large error. Figure 2 shows the situation where the dual-media model (left) and the discrete fracture model (right) are suitable.

Therefore, there are following disadvantages in the dual medium model technology in the prior art:

1) It is impossible to treat cracks of different scales separately;

2) For areas where fractures are scattered or some large fractures play a dominant role, the accuracy is low.

To sum up, the existence of multi-scale fractures makes the numerical simulation calculation efficiency of the discrete fracture model unsuitable, and usually only dual-media models can be used for modeling and numerical simulation. However, due to the rough description and equivalent treatment of fractures in the dual-media model, the accuracy will be greatly reduced, and large errors may occur in the case of crude oil flow in some main fracture control areas.

Contents of the invention

The technical problem to be solved by the present invention is to provide a multi-scale fracture fine geological modeling and numerical simulation method and device that can take into account both calculation accuracy and calculation efficiency.

In order to solve the problems of the technologies described above, the present invention provides technical solutions as follows:

On the one hand, a multi-scale fracture fine geological modeling and numerical simulation method is provided, including:

Step 1: loading data, the data includes a corner grid model, a matrix property model, a fracture network model and a fracture property model;

Step 2: According to the fracture parameters, divide the fractures into three grades of I, II and III, which are discrete fracture grade, double-porous medium grade and equivalent medium grade respectively. Among them, grade I corresponds to the largest fracture scale, and grade II corresponds to The fracture scale is medium, and the fracture scale corresponding to grade III is the smallest;

Step 3: According to the corner grid model and the geometric information of the I and II fracture systems, generate the unstructured grid G _f of the I and II discrete fractures, and map the matrix properties of the corner grid to it as base mesh;

Step 4: According to the corner point grid model and the geometric information of the I-level fracture system, generate the unstructured grid G _c of the I-level discrete fracture as the digital model grid;

Step 5: Equivalently insert grade III fractures into the matrix grid of _Gf , and calculate their equivalent porosity and permeability;

Step 6: Correspond level II fractures to the digital model grid G _c to become the fracture medium grid in the dual medium model; calculate the numerical simulation parameters of the G _c grid according to the global coarsening method, and the obtained result is a discrete fracture + Dual media hybrid models.

On the other hand, a multi-scale fracture fine geological modeling and numerical simulation model acquisition device is provided, including:

Loading module: used to load data, the data includes corner grid model, matrix property model, fracture network model and fracture property model;

Fracture classification module: used to divide fractures into three grades I, II and III according to fracture parameters, which are discrete fracture grade, double-porous medium grade and equivalent medium grade, among which, grade I corresponds to the largest fracture scale, and grade II Grade III corresponds to a medium-scale fracture, and Grade III corresponds to a minimum fracture scale;

The first grid generation module: it is used to generate the unstructured grid G _f of level I and level II discrete fractures according to the corner point grid model and the geometric information of level I and level II fracture systems, and convert the corner point grid Matrix attributes are mapped to it, as the base grid;

The second grid generation module: according to the corner point grid model and the geometric information of the I-level fracture system, generate the unstructured grid G _c of the I-level discrete fracture as a digital model grid;

The first equivalent calculation module: it is used to equivalent the grade III fractures to the matrix grid of G _f , and calculate its equivalent porosity and permeability;

The second equivalent calculation module: it is used to correspond the grade II fractures to the digital model grid _Gc , and become the fractured medium grid in the dual medium model; according to the global coarsening method, calculate the numerical simulation parameters of the _Gc grid, The result obtained is a discrete fracture + dual-medium mixture model.

The present invention has the following beneficial effects:

In the above scheme, cracks of different sizes are classified and screened.

(1) Small-scale (level III) fractures are treated as equivalent media. In the equivalent numerical simulation model, level III fractures do not need additional numerical simulation grids, which avoids the small-scale, large number and data uncertainty High-resolution modeling and modeling of larger fractures can greatly reduce the calculation cost, and can greatly improve the efficiency of numerical calculation with little loss of accuracy.

(2) For mesoscale (level II) fractures, dual-medium treatment is adopted, and the global coarsening process is adopted, which can ensure the equivalent accuracy of II fractures. In the final numerical simulation model, the second-level fractures are represented by dual-medium grids, and only Add few meshes for numerical simulations.

(3) Discrete fracture processing for large-scale (level I) fractures can accurately describe and simulate fractures that play an important role in the reservoir, maintaining the high precision of traditional discrete fracture models.

To sum up, the method of the present invention adopts separate processing for cracks of different scales and reliability, and uses different numerical simulation strategies in a targeted manner, which ensures the accuracy of numerical calculation and improves the efficiency of numerical calculation.

Description of drawings

Fig. 1 is a schematic diagram of a fractured reservoir (left) and its corresponding dual-media model (middle) and discrete fracture model (right) in the prior art;

Fig. 2 is a schematic diagram of a fractured reservoir suitable for the application of the dual-media model (left) and the discrete fracture model (right) in the prior art;

Fig. 3 is the schematic diagram that obtains unstructured grid G _f as basic grid in the present invention;

Fig. 4 is the schematic diagram that obtains unstructured grid G _c as digital-analog grid in the present invention;

Fig. 5 is a schematic diagram of porosity attributes obtained when reading corner grids and their attributes in the present invention;

Fig. 6 is a schematic diagram of fracture grading according to the fracture network geometric data read in the present invention, wherein the upper part is III-level cracks, the lower left is II-level cracks, and the lower right is: I-level cracks;

Fig. 7 is a schematic diagram of generating a model boundary according to the read corner grid information in steps 3 and 4 of the present invention;

Fig. 8 is a schematic diagram of dividing an unstructured grid Gf based on I+II level discrete fractures in the present invention;

Fig. 9 is a schematic diagram of mapping matrix properties from corner point grids to Gf grids in the present invention, wherein the porosity properties are shown in the figure;

Fig. 10 is a schematic diagram of dividing an unstructured grid Gc based on class I discrete fractures in the present invention;

Fig. 11 is a schematic diagram of calculating the parameters of grade III fractures, where the right figure is the equivalent permeability of grade III fractures;

Fig. 12 is a schematic diagram of the coarsening of the hybrid model (obtaining parameters such as conductivity);

Fig. 13 is a test calculation example adopting the method of the present invention, wherein the upper figure is a saturation distribution diagram of the comparison model numerical simulation results (the numerical simulation calculation time is 1619 seconds), and the lower figure is the saturation distribution of the mixed grid numerical simulation results of the present invention Figure (numerical simulation calculation time is 88 seconds), the error of the two is only 5%, and the calculation is only 1/18 of the original;

Fig. 14 is a schematic diagram of the flow principle of the method of the present invention.

detailed description

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will describe in detail with reference to the drawings and specific embodiments.

Usually there are fractures of different sizes and properties in the reservoir, such as:

(1) The main fractures of fracturing are usually large in size, strong in conductivity, and have a great impact on fluid seepage and reservoir development. In terms of distribution, the number of such fractures is small and sparsely distributed. Since a single fracture has a great influence on seepage and the distribution is relatively sparse, for this type of fracture, the traditional dual-media model will have a large error, and the discrete fracture model is more accurate and effective.

(2) Some fractures, such as fracturing fracture network and natural fracture network, are usually medium in size and have strong flow conductivity. They are distributed in a network-like staggered distribution, which is suitable for dual-media model simulation. If the discrete fracture model is used, the grid There are too many problems and the calculation speed is too slow.

(3) There are still some micro-fractures in the reservoir, and these fractures are very densely distributed. However, due to the small size of the fractures, an effective fracture network may not be formed. Therefore, neither the discrete fracture model nor the dual fracture model is suitable for such fractures. The medium model is simulated, and its properties can be assigned to the substrate through specific methods.

It can be seen that using a single dual-media model or a discrete fracture model cannot effectively simulate different types of fractures in the reservoir. method to build the model, and finally unified into a mixed model for numerical simulation.

On the one hand, the present invention provides a multi-scale fracture fine geological modeling and numerical simulation method, as shown in Fig. 3-14, including the following steps:

Step 1: load (read) data, the data includes corner grid model, matrix property model, fracture network model and fracture property model;

The sources of each data are explained as follows:

(1) Corner mesh model

The corner grid model can generally be generated by 3D geological modeling software and exported to Eclipse corner grid file (*.GRDECL) format. The commonly used 3D geological modeling software includes Petrel, SKUA/GOCAD, RMS, etc.

(2) Matrix attribute model

The matrix attribute model is established after the corner point grid model is generated, and it is usually completed in 3D geological modeling software, and it can also be completed with the help of professional geostatistical software such as GsLib. Establishing a model for each attribute requires hard data as input data. According to its source, hard data can be divided into core data, logging data, seismic data, etc. Under the constraints of hard data, modeling through specific attributes The method establishes the attribute model corresponding to the grid, that is, assigns attributes to each grid unit. Common attribute modeling methods include stochastic simulation methods (such as Gaussian sequential simulation methods), interpolation methods (such as ordinary kriging methods), and expression evaluation methods. The matrix attribute model is based on the corner point grid model in (1), including three attributes of the matrix: porosity, permeability and net-to-gross ratio.

(3) Fracture network model

Fracture network models are generally established by professional fracture modeling software. Common fracture modeling software includes Fraca, FracMan, etc. With the deepening and popularization of fracture model research, many 3D geological modeling software (such as Petrel, GOCAD, etc.) also support fracture modeling software. network modeling. Export and save as GOCAD surface file (*.ts) format after modeling.

(4) Fracture attribute model

The fracture attribute model is usually established together with the fracture network model, which can be automatically calculated by the software for establishing the fracture network model, or can be input manually. Generally, it includes fracture opening and permeability.

Step 2: Crack Grading

According to the fracture parameters, the fractures are divided into three grades: I, II and III, which are discrete fracture grade, double-porous medium grade and equivalent medium grade respectively. Among them, the fracture scale corresponding to grade I is the largest, and the fracture scale corresponding to grade II is medium. , the fracture scale corresponding to grade III is the smallest;

Specifically, fractures can be divided into three levels according to the scale of the fracture (such as length, height, and opening), the conductivity of the fracture, and the distribution of the fracture:

(1) Discrete crack level (level I)

This level of fractures has the largest scale and strong conductivity, and a single fracture has the greatest impact on fluid seepage, and exists as discrete fractures in the final digital model;

(2) Double-hole medium grade (II grade)

The scale of fractures at this level is medium, the connectivity of fractures at the same level is relatively good, and a single fracture has a moderate influence on fluid seepage. In the final numerical simulation model, the fracture medium of the dual-media model exists;

(3) Equivalent medium level (level III)

The scale of fractures at this level is the smallest, and a single fracture has the least impact on fluid seepage. In the final digital model, its effect on seepage is equivalent to the matrix grid.

The specific grading steps can be:

(1) Class I cracks

According to the preset grade I-II fracture classification parameters, including critical length L ₁ , critical opening d ₁ , and critical permeability k ₁ , in the fracture network F, the subset F _I ={f∈F|L _f >L ₁ and d _f >d ₁ and k _f >k ₁ } are class I fractures;

(2) Class III cracks

According to the preset grade II-III fracture classification parameters, including critical length L ₂ , critical opening d ₂ , and critical permeability k ₂ , in the fracture network F, subset F _III ={f∈F|L _f <L ₂ or d _f <d ₂ or k _f <k ₂ } are class III cracks;

(3) Grade II cracks

The subset F _II =FF _I -F _III of the fracture network F is class II fractures.

Step 3: Generate the base mesh G _f

According to the corner grid model and the geometric information of the I and II fracture systems, the unstructured grid G _f of the I and II discrete fractures is generated, and the matrix properties of the corner grid are mapped to it as the basic grid ;

In this step, according to the corner point grid model and the geometric information of the I+II fracture system, the unstructured grid G _f of the I+II discrete fractures is subdivided as the basic grid (as shown in Fig. 3 ). Specifically, the following sub-steps may be included:

(1) Generate model boundaries

According to the input corner grid, the outer envelope surface of the model is generated as the boundary of the unstructured grid G _f ;

(2) Split unstructured grid G _f

Mesh division can be done by mesh generation software such as Triangle, TetGen or CGAL;

(3) Mapping matrix attributes

For any grid g in G _f , find the corner grid corresponding to the grid according to the coordinates of its center point, and assign the matrix properties of the corner grid to grid g one by one.

This grid has all the parameters for numerical simulation. In fact, the basic grid model is the traditional discrete fracture model. Compared with the hybrid grid model proposed in this patent, the basic grid model The price is higher. Therefore, in this patented technology, the basic grid model is only used as a basis for follow-up work, and is not directly used for numerical simulation calculations. In the follow-up work, the calculation of grade III fracture parameters and the coarsening steps of the hybrid model are carried out on the basis of this grid.

Step 4: Generate digital-analog grid G _c

According to the corner point grid model and the geometric information of the I-level fracture system, the unstructured grid G _c of the I-level discrete fracture is generated as a digital model grid;

This step is similar to step 3, the difference is that here only unstructured grid division is performed on class I fractures, and there is no need to map matrix properties (performed in the mixed model coarsening step).

In this step, the unstructured grid _Gc of level I discrete fractures (as shown in Fig. 4) is obtained as the final digital-analog grid. Since the final numerical simulation model parameters are obtained by coarsening the hybrid grid, no attribute mapping is required in this step.

Specifically, this step may include the following sub-steps:

(1) Generate model boundaries

According to the input corner grid, the outer envelope surface of the model is generated as the boundary of the unstructured grid G _c ;

(2) Split unstructured grid G _c

Mesh division can be done by mesh generation software such as Triangle, TetGen or CGAL.

This grid is the carrier of the final hybrid grid, that is, the final numerical simulation model is based on this grid.

Step 5: Calculation of Grade III Fracture Parameters

Equivalent the grade III fractures to the matrix grid of G _f , and calculate their equivalent porosity and permeability;

In this step, based on the basic grid G _f in step 3, class III fractures are equivalent to the matrix grid of G _f . The reason why the class III fracture parameters are equivalent to the basic grid G _f instead of the digital model grid G _c is that the former already has all the numerical model information except the class III fracture, while the latter lacks the class II fracture and other Therefore, the grade III fractures are equivalently calculated to the basic grid G _f , and the final hybrid grid upscaling step can obtain a hybrid grid model with complete information.

In the calculation of grade III fracture parameters, the porosity can be equivalent to the traditional calculation method (see the following formula), and the permeability is preferably equivalent to the flow-based local coarsening method. That is, for any grid g in G _f :

(1) Traverse F _III to determine all grade III cracks falling inside the grid

(2) To correct matrix porosity, the calculation formula is

${\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; g</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}$

Wherein, φ is the porosity, V is the volume;

(3) To correct matrix permeability, the calculation formula is

${\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Q</span>}\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; P</span>}$

where Q is the total flow of the grid cross-section perpendicular to the permeability direction, d is the grid length in the permeability direction, A is the average area of the grid cross-section perpendicular to the permeability direction, and ΔP is the pressure gradient in the permeability direction weight.

Due to the small fracture scale and high uncertainty of this level, it is not necessary to perform global discrete fracture characterization, and only need to perform equivalent calculations in a single grid block of the unstructured grid G _f .

After the calculation of equivalent parameters is completed, grade III fractures can be eliminated from the fracture network.

Step 6: Mixture Model Coarsening

Corresponding level II fractures to the digital model grid G _c becomes the fracture medium grid in the dual medium model; according to the global coarsening method, the numerical simulation parameters of the G _c grid are calculated, and the result obtained is discrete fracture + dual medium Hybrid model.

The aforementioned steps have generated a set of basic grid G _f with complete numerical model information. The disadvantage is that the number of grids is too large, and the calculation cost of numerical simulation is too high. In addition, in step 4, the unstructured grid G _c used in the final numerical simulation is also obtained. Compared with G _f , the numerical simulation grid G _c is much less, but so far, it only contains the information of class I fractures . Therefore, the goal of this step is to assign the information of the basic grid G _f (level II fractures and other matrix properties) to the digital model grid G _c through the coarsening method.

In order to achieve the above goals, this step adopts the flow-based global coarsening method to obtain all the parameters of the final numerical simulation model. The work is divided into two parts. One is to map II-level fractures to the G _c grid and become a dual medium The fracture medium grid in the model, the second is to calculate the numerical simulation parameters of the _Gc grid, and the result obtained is a discrete fracture + dual medium mixed model. Specific steps such as:

(1) traverse F _II and determine all II-level cracks falling inside each grid of G _c ;

(2) To calculate the porosity of the fracture grid, the calculation formula is

${\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}}^{\mathrm{<span\; class="notranslate">\; g</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}$

where φ is the porosity, V is the volume,

(3) According to the global coarsening method, the conductivities T _MM , T _FF and T _MF are calculated respectively, where T is the conductance, M and F refer to the matrix and the fracture grid, respectively. Note that here F has two levels of cracks, I and II, so the conductivity can be further subdivided into T _MM ,

So far, the final numerical simulation parameters based on the G _c grid are obtained:

(1) Numerical simulation of the porosity of the grid;

(2) The control point depth of the numerical simulation grid;

(3) The volume of the numerical simulation grid;

(4) Conductivity connectivity table of numerical simulation grid.

Fig. 13 is a test calculation example adopting the method of the present invention, wherein the upper figure is a saturation distribution diagram of the comparison model numerical simulation results (the numerical simulation calculation time is 1619 seconds), and the lower figure is the saturation distribution of the mixed grid numerical simulation results of the present invention Figure (numerical simulation calculation time is 88 seconds), the error of the two is only 5%, and the calculation is only 1/18 of the original.

On the other hand, corresponding to the above method, the present invention also provides a multi-scale fracture fine geological modeling and numerical simulation device, including:

Loading module: used to load data, the data includes corner grid model, matrix property model, fracture network model and fracture property model;

Fracture classification module: used to divide fractures into three grades I, II and III according to fracture parameters, which are discrete fracture grade, double-porous medium grade and equivalent medium grade, among which, grade I corresponds to the largest fracture scale, and grade II Grade III corresponds to a medium-scale fracture, and Grade III corresponds to a minimum fracture scale;

The first grid generation module: it is used to generate the unstructured grid G _f of level I and level II discrete fractures according to the corner point grid model and the geometric information of level I and level II fracture systems, and convert the corner point grid Matrix attributes are mapped to it, as the base grid;

The second grid generation module: according to the corner point grid model and the geometric information of the I-level fracture system, generate the unstructured grid G _c of the I-level discrete fracture as a digital model grid;

The first equivalent calculation module: it is used to equivalent the grade III fractures to the matrix grid of G _f , and calculate its equivalent porosity and permeability;

The second equivalent calculation module: it is used to correspond the grade II fractures to the digital model grid _Gc , and become the fractured medium grid in the dual medium model; according to the global coarsening method, calculate the numerical simulation parameters of the _Gc grid, The result obtained is a discrete fracture + dual-medium mixture model.

Further, the crack classification module preferably includes:

The first grading sub-module: according to the preset grade I-II fracture grading parameters, including critical length L ₁ , critical opening d ₁ , and critical permeability k ₁ , in the fracture network F, the subset F _I ={ f∈F|L _f >L ₁ and d _f >d ₁ and k _f >k ₁ } are Class I fractures;

The second grading sub-module: according to the preset II-III fracture grading parameters, including critical length L ₂ , critical opening d ₂ , and critical permeability k ₂ , in the fracture network F, subset F _III ={ f∈F|L _f <L ₂ or d _f <d ₂ or k _f <k ₂ } are class III cracks;

The third grading sub-module: the subset F _II =FF _I -F _III of the fracture network F is grade II fractures.

Further, the first grid generation module preferably includes:

The first model boundary generation submodule: used to generate the outer envelope surface of the model as the boundary of the unstructured grid G _f according to the input corner grid;

The first dissection sub-module: used to divide unstructured grid G _f ;

Mapping sub-module: For any grid g in G _f , find the corner grid corresponding to the grid according to its center point coordinates, and assign the matrix properties of the corner grid to grid g one by one.

Further, the second grid generation module preferably includes:

The second model boundary generation submodule: used to generate the outer envelope surface of the model according to the input corner grid, as the unstructured grid _Gc boundary;

The second dissection submodule: used for dissection of the unstructured grid G _c .

Further, in the first equivalent calculation module, when calculating the grade III fracture parameters, the porosity can be equivalent using the traditional calculation method, and the permeability can preferably be equivalent using the flow-based local coarsening method.

The above description is a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. A multi-scale fracture fine geological modeling and numerical simulation method, characterized in that it includes: Step 1: loading data, the data includes a corner grid model, a matrix property model, a fracture network model and a fracture property model; Step 2: According to the fracture parameters, divide the fractures into three grades of I, II and III, which are discrete fracture grade, double-porous medium grade and equivalent medium grade respectively. Among them, grade I corresponds to the largest fracture scale, and grade II corresponds to The fracture scale is medium, and the fracture scale corresponding to grade III is the smallest; Step 3: According to the corner grid model and the geometric information of the I and II fracture systems, generate the unstructured grid G _f of the I and II discrete fractures, and map the matrix properties of the corner grid to it as base mesh; Step 4: According to the corner point grid model and the geometric information of the I-level fracture system, generate the unstructured grid G _c of the I-level discrete fracture as the digital model grid; Step 5: Equivalently insert grade III fractures into the matrix grid of _Gf , and calculate their equivalent porosity and permeability; Step 6: Correspond level II fractures to the digital model grid G _c to become the fracture medium grid in the dual medium model; calculate the numerical simulation parameters of the G _c grid according to the global coarsening method, and the obtained result is a discrete fracture + Dual media hybrid models. 2. multi-scale fracture fine geological modeling and numerical simulation method according to claim 1, is characterized in that, described step 2 comprises: Step 21: According to the preset grade I-II fracture classification parameters, including critical length L ₁ , critical opening d ₁ , and critical permeability k ₁ , in the fracture network F, the subset F _I ={f∈F |L _f >L ₁ and d _f >d ₁ and k _f >k ₁ } are Class I fractures; Step 22: According to the preset grade II-III fracture classification parameters, including critical length L ₂ , critical opening d ₂ , and critical permeability k ₂ , in the fracture network F, subset F _III ={f∈F |L _f <L ₂ or d _f <d ₂ or k _f <k ₂ } are class III cracks; Step 23: The subset F _II =FF _I -F _III of the fracture network F is class II fractures. 3. multi-scale fracture fine geological modeling and numerical simulation method according to claim 2, is characterized in that, described step 3 comprises: Step 31: According to the input corner point grid, generate the outer envelope surface of the model as the boundary of the unstructured grid G _f ; Step 32: Subdividing the unstructured grid G _f ; Step 33: For any grid g in G _f , find the corner grid corresponding to the grid according to the coordinates of its center point, and assign the matrix properties of the corner grid to grid g one by one. 4. multi-scale fracture fine geological modeling and numerical simulation method according to claim 3, is characterized in that, described step 4 comprises: Step 41: According to the input corner grid, generate the outer envelope surface of the model as the boundary of the unstructured grid _Gc ; Step 42: Subdividing the unstructured grid G _c . 5. The multi-scale fracture fine geological modeling and numerical simulation method according to claim 4, characterized in that, in the step 5, when calculating the parameters of grade III fractures, the porosity is equivalent to the traditional calculation method, and the permeability is equivalent to Flow-based local coarsening methods are equivalent. 6. A multi-scale fracture fine geological modeling and numerical simulation device, characterized in that it includes: Loading module: used to load data, the data includes corner grid model, matrix property model, fracture network model and fracture property model; Fracture classification module: used to divide fractures into three grades I, II and III according to fracture parameters, which are discrete fracture grade, double-porous medium grade and equivalent medium grade, among which, grade I corresponds to the largest fracture scale, and grade II Grade III corresponds to a medium-scale fracture, and Grade III corresponds to a minimum fracture scale; The first grid generation module: it is used to generate the unstructured grid G _f of level I and level II discrete fractures according to the corner point grid model and the geometric information of level I and level II fracture systems, and convert the corner point grid Matrix attributes are mapped to it, as the base grid; The second grid generation module: according to the corner point grid model and the geometric information of the I-level fracture system, generate the unstructured grid G _c of the I-level discrete fracture as a digital model grid; The first equivalent calculation module: it is used to equivalent the grade III fractures to the matrix grid of G _f , and calculate its equivalent porosity and permeability; The second equivalent calculation module: it is used to correspond the grade II fractures to the digital model grid _Gc , and become the fractured medium grid in the dual medium model; according to the global coarsening method, calculate the numerical simulation parameters of the _Gc grid, The result obtained is a discrete fracture + dual-medium mixture model. 7. The multi-scale fracture fine geological modeling and numerical simulation device according to claim 6, wherein the fracture classification module comprises: The first grading sub-module: according to the preset grade I-II fracture grading parameters, including critical length L ₁ , critical opening d ₁ , and critical permeability k ₁ , in the fracture network F, the subset F _I ={ f∈F|L _f >L ₁ and d _f >d ₁ and k _f >k ₁ } are Class I fractures; The second grading sub-module: according to the preset II-III fracture grading parameters, including critical length L ₂ , critical opening d ₂ , and critical permeability k ₂ , in the fracture network F, subset F _III ={ f∈F|L _f <L ₂ or d _f <d ₂ or k _f <k ₂ } are class III cracks; The third grading sub-module: the subset F _II =FF _I -F _III of the fracture network F is grade II fractures. 8. The multi-scale fracture fine geological modeling and numerical simulation device according to claim 7, wherein the first grid generation module comprises: The first model boundary generation submodule: used to generate the outer envelope surface of the model as the boundary of the unstructured grid G _f according to the input corner grid; The first dissection sub-module: used to divide unstructured grid G _f ; Mapping sub-module: for any grid g in G _f , find the corner grid corresponding to the grid according to its center point coordinates, and assign the matrix properties of the corner grid to grid g one by one. 9. The multi-scale fracture fine geological modeling and numerical simulation device according to claim 8, wherein the second grid generation module comprises: The second model boundary generation submodule: used to generate the outer envelope surface of the model according to the input corner grid, as the unstructured grid _Gc boundary; The second dissection submodule: used for dissection of the unstructured grid G _c . 10. The multi-scale fracture fine geological modeling and numerical simulation device according to claim 9, characterized in that, in the first equivalent calculation module, when calculating the parameters of grade III fractures, the porosity is equivalent to the traditional calculation method , the permeability is equivalent using a flow-based local upscaling method.