Fluid permeability prediction method and system of dual pore-fracture network

Abstract

The invention belongs to the technical field of permeability prediction, and particularly relates to a fluid permeability prediction method and system of a dual pore-fracture network. The method comprises the following steps: establishing an intergranular pore flow channel model based on a fluid mechanics model, and calculating to obtain a flow state of an intergranular pore network; establishing a pressure-flow velocity linear equation set of the intergranular pore network according to the flow state, and solving to obtain pressure and flow velocity values at different positions in the intergranular pore network; according to the node flow conservation law in the fracture network, fluid velocity and pressure distribution in the fracture network are obtained; and establishing a coupling linear equation set according to the pressure and flow velocity values at different positions in the intergranular pore network and the fluid velocity and pressure distribution in the fracture network, and solving to obtain flow exchange data in the dual pore-fracture network space. According to the method, the three-dimensional fracture-pore network structure model of the cross-microscopic-mesoscopic-macroscopic scale is established, and the dynamic permeability of the double-scale fractured compact rock can be predicted.

Description

Technical Field

[0001] The present invention belongs to the technical field of permeability prediction, and in particular relates to a method and system for predicting fluid permeability of a dual pore-fracture network. Background Art

[0002] The prediction of dual-porosity fracture fluid permeability is a key issue in the exploration and development of oil and gas reservoirs. Reservoirs may contain fractures and dense matrix pores, both of which have a significant impact on fluid permeability. Therefore, accurately predicting the permeability of fluids in reservoirs is an important factor in evaluating and developing reservoirs.

[0003] The method commonly used to predict the permeability of porous rock fluids is to use a network structure model. However, this traditional model has the following disadvantages:

[0004] (1) For complex rock structures and fracture networks, the model simplifies the actual situation and lacks accuracy;

[0005] (2) The model is based on the assumption of uniformity, while the rock structure and fracture network often have heterogeneous characteristics and cannot fully reflect the actual situation;

[0006] (3) The parameters of the model need to undergo complex experimental tests or be derived from other models, and there is a lack of direct experimental data;

[0007] (4) The model may produce inconsistent results for different seepage conditions and geological environments, making it difficult to apply universally. Summary of the invention

[0008] In view of the above problems, the present invention provides a method for predicting fluid permeability of a dual pore-fracture network, the method comprising:

[0009] Based on the fluid mechanics model, the intergranular pore flow channel model is established to calculate the flow state of the intergranular pore network;

[0010] According to the flow state, the pressure-velocity linear equations of the intergranular pore network are established, and the pressure and velocity values ​​at different positions in the intergranular pore network are obtained by solving them;

[0011] According to the law of conservation of nodal flow in the fracture network, the fluid velocity and pressure distribution in the fracture network are obtained;

[0012] According to the pressure and velocity values ​​at different positions in the intergranular pore network and the fluid velocity and pressure distribution in the fracture network, a coupled linear equation system is established and the flow exchange data in the dual pore-fracture network space is obtained by solving it.

[0013] Predict flow in dual pore-fracture networks based on flow exchange data;

[0014] The fluid permeability of the dual pore-fracture network is predicted by combining the inlet-outlet pressure difference with the flow rate in the dual pore-fracture network.

[0015] Preferably, the establishment of the intergranular pore flow channel model based on the fluid mechanics model includes:

[0016] Based on the velocity field of pore fluid and the flow formula of incompressible Newtonian fluid in a single tube, the flow calculation formula of intergranular pores is obtained by using the Navier-Stokes equations and the symmetry condition of the elliptical section in the elliptical cylindrical coordinate system and the no-slip boundary condition of the inner wall of the pipe.

[0017] Preferably, the pore fluid velocity field includes a steady-state field and a non-steady-state field.

[0018] Preferably, the flow state includes the flow rate and flow velocity of the fluid.

[0019] Preferably, the flow state of the inter-particle pore network is obtained by calculation, including:

[0020] Calculate the flow velocity in the flow channel through the intergranular pore flow channel model;

[0021] The volume of fluid flowing through the flow channel per unit time is obtained by the flow velocity;

[0022] Combining the fluid volume with the flow calculation formula, the flow rate of the interparticle pore network is obtained.

[0023] Preferably, the predicting of the flow in the dual pore-fracture network based on the flow exchange data comprises:

[0024] The pore and flow exchange data at the interface of the dual pore-fracture network are combined to establish a coupled linear equation for flow exchange;

[0025] Solve the flow exchange coupling linear equation to obtain the pressure and flow at the interface nodes of the pore network and fracture network;

[0026] The flow rate in a dual pore-fracture network is predicted using the pressure and flow rate at the interface nodes of the pore network and the fracture network.

[0027] The present invention also provides a fluid permeability prediction system for a dual pore-fracture network, the system comprising a first acquisition module, an information processing module, a second acquisition module, an integration module, a first prediction module and a second prediction module;

[0028] The first acquisition module is used to establish an intergranular pore flow channel model based on a fluid mechanics model, and calculate the flow state of the intergranular pore network;

[0029] The information processing module is used to establish a pressure-flow rate linear equation group of the intergranular pore network according to the flow state, and solve the pressure and flow rate values ​​at different positions in the intergranular pore network;

[0030] The second acquisition module is used to obtain the fluid velocity and pressure distribution in the fracture network according to the law of conservation of node flow in the fracture network;

[0031] The integration module is used to establish a coupled linear equation group according to the pressure and flow velocity values ​​at different positions in the intergranular pore network and the fluid velocity and pressure distribution in the fracture network, and solve to obtain the flow exchange data in the dual pore-fracture network space;

[0032] The first prediction module is used to predict the flow in the dual pore-fracture network based on the flow exchange data;

[0033] The second prediction module is used to predict the fluid permeability of the dual pore-fracture network by combining the inlet-outlet pressure difference with the flow rate in the dual pore-fracture network.

[0034] Preferably, the first acquisition module is used to establish a flow channel model of intergranular pores, including:

[0035] The first acquisition module is based on the pore fluid velocity field and the flow formula of incompressible Newtonian fluid in a single tube. In the elliptical cylindrical coordinate system and the no-slip boundary conditions of the inner wall of the pipeline, the flow calculation formula of the intergranular pores is obtained using the Navier-Stokes equations and the symmetry conditions of the elliptical section.

[0036] Preferably, the first acquisition module is used to calculate the flow state of the intergranular pore network, including:

[0037] The first acquisition module is used to calculate the flow velocity in the flow channel through the intergranular pore flow channel model;

[0038] The volume of fluid flowing through the flow channel per unit time is obtained by the flow velocity;

[0039] Combining the fluid volume with the flow calculation formula, the flow rate of the interparticle pore network is obtained.

[0040] Preferably, the first prediction module is used to predict the flow in the dual pore-fracture network according to the flow exchange data, including:

[0041] The first prediction module is used to combine the pores on the interface of the dual pore-fracture network with the flow exchange data to establish a flow exchange coupling linear equation;

[0042] Solve the flow exchange coupling linear equation to obtain the pressure and flow at the interface nodes of the pore network and fracture network;

[0043] The flow rate in a dual pore-fracture network is predicted using the pressure and flow rate at the interface nodes of the pore network and the fracture network.

[0044] The present invention also provides an electronic device, comprising:

[0045] Processor and memory;

[0046] The processor calls the computer program stored in the memory to execute any one of the above-mentioned methods for predicting fluid permeability of a dual pore-fracture network.

[0047] The present invention also provides a computer-readable storage medium.

[0048] The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the processor is enabled to execute any of the above-mentioned methods for predicting fluid permeability of a dual pore-fracture network.

[0049] The present invention has the following beneficial effects:

[0050] (1) The present invention establishes a three-dimensional fracture-pore network structure model across micro-meso-macro scales, which can predict the dynamic permeability of dual-scale fractured dense rocks;

[0051] (2) The present invention can be combined with reservoir characteristics to predict fluid flow rate and pressure distribution in porous rocks.

[0052] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 A diagram showing a method for predicting fluid permeability of a dual pore-fracture network in an embodiment of the present invention;

[0055] Figure 2 A schematic diagram of a fracture-matrix block network model in an embodiment of the present invention is shown;

[0056] Figure 3A schematic diagram of the intergranular pore network model inside the matrix block in an embodiment of the present invention is shown;

[0057] Figure 4 A schematic diagram of a fracture network and a matrix block network model in an embodiment of the present invention is shown;

[0058] Figure 5 Schematic diagrams of two scale pore network models in an embodiment of the present invention are shown;

[0059] Figure 6 A schematic diagram showing the fluid pressure distribution in a three-dimensional fracture-pore network containing through fracture surfaces in an embodiment of the present invention is shown;

[0060] Figure 7 A schematic diagram showing the fluid pressure distribution in the XZ plane in a three-dimensional fracture-pore network containing through fracture surfaces in an embodiment of the present invention is shown;

[0061] Figure 8 A schematic diagram showing the distribution of fluid flow rate in a three-dimensional fracture-pore network containing through fracture surfaces in an embodiment of the present invention is shown;

[0062] Fig. 9 A schematic diagram showing the fluid velocity distribution in the XZ plane in a three-dimensional fracture-pore network containing through fracture surfaces in an embodiment of the present invention is shown;

[0063] Fig.10 A schematic diagram showing the fluid pressure distribution in a three-dimensional fracture-pore network containing through fracture surfaces in an embodiment of the present invention is shown;

[0064] Fig.11 A schematic diagram showing the fluid pressure distribution in the XZ plane in a three-dimensional fracture-pore network containing through fracture surfaces in an embodiment of the present invention is shown;

[0065] Fig.12 A schematic diagram showing the distribution of fluid flow rate in a three-dimensional fracture-pore network containing through fracture surfaces in an embodiment of the present invention is shown;

[0066] Fig.13 A schematic diagram showing the fluid velocity distribution in the XZ plane in a three-dimensional fracture-pore network containing through fracture surfaces in an embodiment of the present invention is shown;

[0067] Fig.14 A diagram showing a fluid permeability prediction system for a dual pore-fracture network in an embodiment of the present invention;

[0068] Fig.15 A diagram of an electronic device in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0069] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as being limited to the examples set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be more comprehensive and complete, and the concepts of the example embodiments are fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0070] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware units or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0071] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the steps. For example, some steps may be decomposed, while some steps may be combined or partially combined, so the actual execution order may change according to the actual situation.

[0072] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example.

[0073] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or sub-modules is not necessarily limited to those steps or sub-modules explicitly listed, but may include other steps or sub-modules not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0074] The dual pore-fracture network model is a method for predicting fluid permeability in porous rocks containing fractures. It simulates the flow of fluids in the reservoir by considering the permeability and flow interaction of fractures and porous media, and then calculates the total permeability of the reservoir based on the fluid flow simulation results. By using these methods, the effects of different reservoir characteristics (such as fracture density and size, porous media type and permeability, etc.) on fluid permeability can be evaluated.

[0075] The method for predicting fluid permeability in dual pore-fracture network systems involves simulating the flow of fluids in porous media with multiple interconnections. The fractures and the surrounding porous media are treated as two different porous regions, each with its own permeability. The fluid flow in the fractures can be described using Darcy's law, while the flow in the porous media can be described using the cubic law or other more complex models to obtain the total permeability of the system by combining the permeabilities of the two regions and considering the flow interaction between them.

[0076] like Figure 1 As shown, the present invention proposes a method for predicting fluid permeability of a dual pore-fracture network, the method comprising the following steps:

[0077] S1. Establish a flow channel model of interparticle pores based on the fluid mechanics model and calculate the flow state of the interparticle pore network;

[0078] The flow channel model of intergranular pores is established based on the fluid mechanics model, including:

[0079] Based on the pore fluid velocity field and the flow formula of incompressible Newtonian fluid in a single tube, the flow calculation formula of the interparticle pores is obtained by using the Navier-Stokes equations and the symmetry conditions of the elliptical cross section in the elliptical cylindrical coordinate system and the no-slip boundary conditions of the inner wall of the pipe. Among them, the pore fluid velocity field includes steady-state field and unsteady-state field, and the flow state includes the flow rate and flow velocity of the fluid.

[0080] The flow state of the intergranular pore network is obtained by calculation, including: calculating the flow velocity in the flow channel through the intergranular pore flow channel model; obtaining the volume of fluid flowing through the flow channel per unit time through the flow velocity; and combining the fluid volume with the flow calculation formula to obtain the flow of the intergranular pore network.

[0081] S2. Establishing a pressure-velocity linear equation group of the intergranular pore network according to the flow state, and solving it to obtain the pressure and velocity values ​​at different positions in the intergranular pore network;

[0082] S3, according to the law of conservation of node flow in the fracture network, the fluid velocity and pressure distribution in the fracture network are obtained;

[0083] S4, establishing a coupled linear equation system according to the pressure and flow velocity values ​​at different positions in the intergranular pore network and the fluid velocity and pressure distribution in the fracture network, and solving them to obtain the flow exchange data in the dual pore-fracture network space;

[0084] S5, predicting the flow in the dual pore-fracture network based on the flow exchange data;

[0085] It includes: combining the pore and flow exchange data on the interface of the dual pore-fracture network to establish the flow exchange coupling linear equation; solving the flow exchange coupling linear equation to obtain the pressure and flow at the interface nodes of the pore network and the fracture network; predicting the flow in the dual pore-fracture network through the pressure and flow at the interface nodes of the pore network and the fracture network.

[0086] Specifically, (1) intergranular pore i is connected to the six nearby pores j = 1, ..., 6, and the flow rate Q between pores i and j is ij The flow rate expression Q(t) of the fluid in the flow tube can be obtained:

[0087]

[0088] Some of these six adjacent pores have fluid flowing into pore i, while others have fluid flowing out of pore i. The flow conservation law is satisfied at the network nodes, that is, the sum of the inflow flow and the outflow flow is zero;

[0089]

[0090] Among them, P i , P j is the fluid pressure at pore i, j;

[0091] (2) Assume that the entire network has 125 pore nodes, that is, i = 1, ..., 125. Then, for each node, a flow conservation equation can be given. All 125 equations construct a large linear system of equations. Solving this system of equations, we can obtain the pressure P on each pore. i and the flow rate Q in each flow tube ij ;

[0092] (3) Similarly, for a fracture network composed of elliptical cylindrical flow tubes, each node also satisfies the flow conservation equation. Assuming that the fracture network has 64 connected nodes, 64 flow conservation equations can be obtained, forming another large linear equation system. Solving this equation system can obtain the fracture pressure and flow in the fracture network.

[0093] (4) Since there are interconnected channels between the intergranular pore network and the fracture network, the two networks exchange flows on these interconnected channels. There are both intergranular pores and fractures near the pore i on the interconnected interface. Therefore, at this pore node, the inflow and outflow flows include the node flows from the two networks. Assuming that there are 3 adjacent pores on this node from the intergranular pore network and 3 from the fracture network, the flow conservation is expressed as:

[0094]

[0095] Where J represents the fracture network node, j represents the intergranular pore network node, and formula (2) represents the conservation condition of flow exchange on the dual network interface;

[0096] (5) Assuming that there are 16 pores on the dual network interface (this parameter is determined based on the actual pore network structure observed in rock physics experiments), then an equation can be established for each pore i = 1, ..., 16 to obtain a coupled linear equation system for flow exchange, which contains 16 equations;

[0097] (6) The linear equations for flow exchange in the two scale flow spaces are solved to obtain the pressure and flow at the interface nodes of the pore network and the fracture network.

[0098] At this point, the flow prediction in the dual pore-fracture network based on the flow exchange data is completed.

[0099] S6. Combining the inlet-outlet pressure difference with the flow rate in the dual pore-fracture network, the fluid permeability of the dual pore-fracture network is predicted.

[0100] Specifically, the present invention first establishes a flow channel model of micro-scale interparticle pores, and the flow channels (radius is in the micrometer level) are interconnected to form a mesoscopic (pipeline length is in the millimeter level)-macroscopic (overall unit is in the centimeter level) overall network, thereby realizing the overall modeling of the fluid connection space in the porous medium.

[0101] Based on the flow formula of incompressible Newtonian fluid in a single tube, the elliptic cylindrical coordinate system is used. The velocity field of the pore fluid contains two components: steady-state field and unsteady-state field. Starting from the Navier-Stokes equation in the elliptic cylindrical coordinate system, considering the no-slip boundary condition of the inner wall of the pipe and using the symmetry condition of the elliptical section, the flow expression of the fluid in the flow tube can be obtained:

[0102]

[0103] Where ω is the fluid pressure pulsation frequency, R1 is the main radius of the flow channel, a is the aspect ratio of the flow channel section, J0 and J1 are zero-order and first-order Bessel functions, and the density and viscosity of the fluid in the pipeline are ρ f, η, λ and k are intermediate variables, defined as is an imaginary unit, is the average value of the cross-sectional radius of the flow tube, t is the time, c is the speed of the sound wave in the fluid, z is the coordinate along the axial direction of the flow tube, and P is the pressure on the cross-sectional area at the z coordinate position.

[0104] Assume that the cross-section of the microscopic intergranular pores is close to a circle, constituting the fluid flow space of the dense matrix. The fluid flows slowly in the pores under the action of pulsating pressure, and the zero flow tube aspect ratio a=1. The above flow formula can be used to establish a flow prediction method in the matrix block.

[0105] Secondly, the dimensions of reservoir fractures in width and height vary greatly, and their cross-sections have a very small aspect ratio. Based on geological survey and analysis data and rock physics experimental observations, the aspect ratio range of the fractures can be determined. By substituting the fracture aspect ratio into the above flow calculation formula, the distribution of the fluid flow in the fracture space over time and space can be predicted.

[0106] Finally, if Figure 2 As shown in Figure 1, a three-dimensional network structure model is formed based on macroscopic fractures and microscopic intergranular pores, and a flow calculation formula for porous rocks in reservoirs containing fracture networks is obtained. Figure 3 As shown in Figure 2, the internal pore channels of the matrix block containing intergranular pores are represented as a circular flow channel network, and the matrix block is divided by larger cracks, such as Figure 4 As shown, the cracks form a network of fluid channels around the matrix block.

[0107] The degree of fracture development plays a very important role in improving reservoir permeability and productivity. Due to the development of fractures, the permeability has been greatly improved. There is fluid coupling flow at the interface between the fluid inside the matrix block and the fluid in the fracture space, so that the fluid pores in the tight porous rock with fractures form a whole, which contains full flow matrix pore space and fast flow fracture space. This dual-porosity medium has a significant impact on fluid permeability, which also brings difficulties to the traditional permeability calculation model.

[0108] Example 1 Fluid flow pattern in a dual-scale pore network with intergranular pores and through-fracture surfaces

[0109] For rocks with intergranular pores and horizontally penetrating fractures, two scale pore-fracture network structures are established. In the Z direction of the fracture-pore network, the plane where the second layer of pores is located is taken as the fracture penetration plane, such as Figure 5 As shown, the channel fluidity between the pores is enhanced.

[0110] The network calculation parameters used are: porosity 0.06, pore throat aspect ratio 0.01, pore radius 0.2 mm, confining pressure 10 atmospheres, and the spatial distribution of flow field pressure is shown in Figure 6and Figure 7 , we can find from the figure:

[0111] (1) The pressure near the pores of the inlet layer is uniformly distributed on the YZ plane, which is consistent with the uniform pressure condition applied on the inlet plane;

[0112] (2) From the inlet layer to the outlet layer, the pressure gradually decreases in space, and the outlet meets the 1 atmosphere pressure boundary condition;

[0113] (3) The second layer position in the Z direction, such as Figure 7 As shown, due to the existence of the through-fracture plane, the fluid flow pattern changes differently from the uniform pore-pore throat structure. The pressure front shows an obvious protrusion feature, and the fluid pressure along the through-fracture plane is significantly higher than the surrounding area, indicating that high-pressure fluid enters the numerical sample along the fracture surface.

[0114] The spatial distribution of fluid velocity in the fracture-pore space is shown in Figure 8 , Fig. 9 As shown. From the fluid velocity distribution diagram, we can find that:

[0115] (1) On the fracture penetration plane, the velocity contour surface shows an obvious protrusion phenomenon, and the velocity of the fluid in the fracture plane layer is significantly higher than that in other nearby locations;

[0116] (2) The maximum fluid velocity in the numerical sample increases from about 0.015 mm / s in the uniform fracture-pore network to about 0.27 mm / s;

[0117] (3) There is still a certain flow velocity at the inlet layer far away from the fracture plane, but the flow velocity at the fracture position is dominant.

[0118] From the above example results analysis, we can draw the following conclusions:

[0119] (1) The through-fracture plane has a strong flow-guiding effect on the fluid, causing a significant change in the fluid flow pattern, from the plane advancement mode of the uniform fracture-pore network (pressure and velocity isosurfaces are parallel to the YZ plane) to the advance mode along the fracture surface;

[0120] (2) At locations with through fracture planes, high-pressure fluids can enter more easily than at other locations;

[0121] (3) The fluid velocity in the fracture-pore network with through-fracture planes is higher than that in the uniform pore-pore throat network, and has a greater permeability.

[0122] Example 2 Effect of pressure on the flow pattern of double pore network fluid

[0123] In order to verify the applicability of the present invention under different pressure conditions, the flow characteristics under 100 atmospheres and 10 atmospheres were calculated respectively. In the Z direction of the fracture-pore network, the plane where the second layer of pores is located is taken as the fracture penetration plane, and the network calculation parameters are: porosity 0.06, pore throat aspect ratio 0.01, pore radius 0.2mm, and confining pressure 100 atmospheres. The spatial distribution of flow field pressure is shown in Fig.10 , Fig.11 , we can find from the figure:

[0124] (1) The distribution of fluid pressure field under the condition of confining pressure of 100 atmospheres is very similar to that under the condition of 10 atmospheres;

[0125] (2) Under the condition of confining pressure of 100 atmospheres, the fluid enters the interior of the numerical sample along the crack penetration plane, and the pressure value at the same position is about 10 times that under the condition of 10 atmospheres.

[0126] The spatial distribution of fluid velocity in the fracture-pore space is shown in Fig.12 and Fig.13 From the fluid velocity distribution diagram under high pressure conditions, it is found that:

[0127] (1) The distribution of the fluid velocity field under the confining pressure of 100 atmospheres is very similar to that under the confining pressure of 10 atmospheres;

[0128] (2) Under the condition of confining pressure of 100 atmospheres, the fluid velocity at the same position is about 10 times that under the condition of 10 atmospheres.

[0129] From the above analysis of the influence of pressure on fluid field pressure and velocity, it is found that:

[0130] (1) As the inlet-outlet pressure gradient increases, the pressure distribution in the fracture-pore space increases in direct proportion;

[0131] (2) As the inlet-outlet pressure gradient increases, the fluid velocity in the fracture-pore space increases in direct proportion;

[0132] (3) Under the condition of the same pore-throat structure, within a certain pressure range, the change of pressure gradient has little effect on the fluid distribution morphology.

[0133] Data analysis shows that the present invention can reflect the changing characteristics of permeability in porous rocks containing fractures under different pressures, and realizes a method for accurately characterizing the internal flow characteristics of fluids in porous rocks containing fractures, which has obvious advantages over other traditional methods.

[0134] like Fig.14As shown, the present invention proposes a fluid permeability prediction system for a dual pore-fracture network, the system comprising a first acquisition module 10, an information processing module 20, a second acquisition module 30, an integration module 40, a first prediction module 50 and a second prediction module 60;

[0135] The first acquisition module 10 is used to establish an intergranular pore flow channel model based on a fluid mechanics model, and calculate the flow state of the intergranular pore network;

[0136] The information processing module 20 is used to establish a pressure-flow rate linear equation group of the intergranular pore network according to the flow state, and solve the pressure and flow rate values ​​at different positions in the intergranular pore network;

[0137] The second acquisition module 30 is used to obtain the fluid velocity and pressure distribution in the fracture network according to the law of conservation of node flow in the fracture network;

[0138] The integration module 40 is used to establish a coupled linear equation group according to the pressure and flow velocity values ​​at different positions in the intergranular pore network and the fluid velocity and pressure distribution in the fracture network, and solve to obtain the flow exchange data in the dual pore-fracture network space;

[0139] The first prediction module 50 is used to predict the flow in the dual pore-fracture network based on the flow exchange data;

[0140] The second prediction module 60 is used to predict the fluid permeability of the dual pore-fracture network by combining the inlet-outlet pressure difference with the flow rate in the dual pore-fracture network.

[0141] like Fig.15 As shown, corresponding to the above-mentioned dual pore-fracture network fluid permeability prediction method, the present invention also provides an electronic device. Since the embodiment of the device is similar to the above-mentioned method embodiment, the description is relatively simple. For relevant parts, please refer to the description of the above-mentioned method embodiment part. The device described below is only schematic. The device may include: a processor (processor) 1, a memory (memory) 2 and a communication bus (i.e., the above-mentioned device bus) and a search engine, wherein the processor 1 and the memory 2 communicate with each other through the communication bus and communicate with the outside through the communication interface. The processor 1 can call the logic instructions in the memory 2 to execute the dual pore-fracture network fluid permeability prediction method.

[0142] In addition, the logic instructions in the above-mentioned memory 2 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: a storage chip, a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a disk or an optical disk, and other media that can store program codes.

[0143] On the other hand, an embodiment of the present invention further provides a processor-readable storage medium, on which a computer program 3 is stored. When the computer program 3 is executed by the processor 1, the fluid permeability prediction method for the dual pore-fracture network provided in the above embodiments is implemented.

[0144] The processor-readable storage medium can be any available medium or data storage device that can be accessed by the processor 1, including but not limited to magnetic storage (such as floppy disks, hard disks, magnetic tapes, magneto-optical disks (MO), etc.), optical storage (such as CD, DVD, BD, HVD, etc.), and semiconductor storage (such as ROM, EPROM, EEPROM, non-volatile memory (NANDFLASH), solid-state drive (SSD)), etc.

[0145] Those skilled in the art should understand that although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible to modify the technical solutions described in the aforementioned embodiments, or to make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for predicting fluid permeability of a dual pore-fracture network, characterized in that: The method comprises: Based on the fluid mechanics model, the intergranular pore flow channel model is established to calculate the flow state of the intergranular pore network; According to the flow state, the pressure-velocity linear equations of the intergranular pore network are established, and the pressure and velocity values ​​at different positions in the intergranular pore network are obtained by solving them; According to the law of conservation of nodal flow in the fracture network, the fluid velocity and pressure distribution in the fracture network are obtained; According to the pressure and velocity values ​​at different positions in the intergranular pore network and the fluid velocity and pressure distribution in the fracture network, a coupled linear equation system is established and the flow exchange data in the dual pore-fracture network space is obtained by solving it. Predict flow in dual pore-fracture networks based on flow exchange data; The fluid permeability of the dual pore-fracture network is predicted by combining the inlet-outlet pressure difference with the flow rate in the dual pore-fracture network.

2. The method for predicting fluid permeability of a dual pore-fracture network according to claim 1, characterized in that: The intergranular pore flow channel model is established based on the fluid mechanics model, including: Based on the velocity field of pore fluid and the flow formula of incompressible Newtonian fluid in a single tube, the flow calculation formula of intergranular pores is obtained by using the Navier-Stokes equations and the symmetry condition of the elliptical section in the elliptical cylindrical coordinate system and the no-slip boundary condition of the inner wall of the pipe.

3. The method for predicting fluid permeability of a dual pore-fracture network according to claim 2, characterized in that: The pore fluid velocity field includes a steady-state field and a non-steady-state field.

4. The method for predicting fluid permeability of a dual pore-fracture network according to claim 1, characterized in that: The flow state includes the flow rate and flow velocity of the fluid.

5. The method for predicting fluid permeability of a dual porosity-fracture network according to claim 1, characterized in that: The flow state of the inter-particle pore network is obtained by calculation, including: Calculate the flow velocity in the flow channel through the intergranular pore flow channel model; The volume of fluid flowing through the flow channel per unit time is obtained by the flow velocity; Combining the fluid volume with the flow calculation formula, the flow rate of the interparticle pore network is obtained.

6. The method for predicting fluid permeability of a dual pore-fracture network according to claim 1, characterized in that: The method of predicting the flow in the dual pore-fracture network based on the flow exchange data includes: The pore and flow exchange data at the interface of the dual pore-fracture network are combined to establish a coupled linear equation for flow exchange; Solve the flow exchange coupling linear equation to obtain the pressure and flow at the interface nodes of the pore network and fracture network; The flow rate in a dual pore-fracture network is predicted using the pressure and flow rate at the interface nodes of the pore network and the fracture network.

7. A fluid permeability prediction system for dual pore-fracture networks, characterized in that: The system includes a first acquisition module, an information processing module, a second acquisition module, an integration module, a first prediction module and a second prediction module; The first acquisition module is used to establish an intergranular pore flow channel model based on a fluid mechanics model, and calculate the flow state of the intergranular pore network; The information processing module is used to establish a pressure-flow rate linear equation group of the intergranular pore network according to the flow state, and solve the pressure and flow rate values ​​at different positions in the intergranular pore network; The second acquisition module is used to obtain the fluid velocity and pressure distribution in the fracture network according to the law of conservation of node flow in the fracture network; The integration module is used to establish a coupled linear equation group according to the pressure and flow velocity values ​​at different positions in the intergranular pore network and the fluid velocity and pressure distribution in the fracture network, and solve to obtain the flow exchange data in the dual pore-fracture network space; The first prediction module is used to predict the flow in the dual pore-fracture network based on the flow exchange data; The second prediction module is used to predict the fluid permeability of the dual pore-fracture network by combining the inlet-outlet pressure difference with the flow rate in the dual pore-fracture network.

8. The fluid permeability prediction system of dual pore-fracture network according to claim 7, characterized in that: The first acquisition module is used to establish a flow channel model of intergranular pores, including: The first acquisition module is based on the pore fluid velocity field and the flow formula of incompressible Newtonian fluid in a single tube. In the elliptical cylindrical coordinate system and the no-slip boundary conditions of the inner wall of the pipeline, the flow calculation formula of the intergranular pores is obtained using the Navier-Stokes equations and the symmetry conditions of the elliptical section.

9. The fluid permeability prediction system of dual pore-fracture network according to claim 7, characterized in that: The first acquisition module is used to calculate the flow state of the intergranular pore network, including: The first acquisition module is used to calculate the flow velocity in the flow channel through the intergranular pore flow channel model; The volume of fluid flowing through the flow channel per unit time is obtained by the flow velocity; Combining the fluid volume with the flow calculation formula, the flow rate of the interparticle pore network is obtained.

10. The fluid permeability prediction system of dual pore-fracture network according to claim 7, characterized in that: The first prediction module is used to predict the flow in the dual pore-fracture network according to the flow exchange data, including: The first prediction module is used to combine the pores on the interface of the dual pore-fracture network with the flow exchange data to establish a flow exchange coupling linear equation; Solve the flow exchange coupling linear equation to obtain the pressure and flow at the interface nodes of the pore network and fracture network; The flow rate in a dual pore-fracture network is predicted using the pressure and flow rate at the interface nodes of the pore network and the fracture network.

11. An electronic device, characterized in that: include: Processor and memory; The processor calls the computer program stored in the memory to execute the method for predicting fluid permeability of a dual pore-fracture network according to any one of claims 1 to 6.

12. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the processor is enabled to execute the method for predicting fluid permeability of a dual pore-fracture network according to any one of claims 1 to 6.

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