Oil and gas reservoir productivity prediction method, device, equipment and storage medium

Abstract

The present application provides a method, device, equipment and storage medium for predicting the productivity of oil and gas reservoirs, and relates to the technical field of oil and gas reservoir development. According to the obtained fracturing characteristics of the shale reservoir to be predicted, a physical model is constructed, and the areas included in the physical model include supported fracture area, unsupported fracture area, fracture transformation inner area, fracture transformation outer area and unfracture transformation area; the seepage control equations of each area in the fixed production stage and the fixed pressure production stage are coupled to obtain a seepage mathematical model; the seepage mathematical model is analytically solved to obtain the bottom hole pressure distribution and oil and gas reservoir production under real space pseudo-time corresponding to the shale reservoir to be predicted, and then the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in real space and real time are obtained. Considering incomplete fracture support, fracture closure and variable production will be more in line with the actual situation, which can improve the accuracy of productivity prediction; using analytical solution method, the calculation speed is faster.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas reservoir development, and in particular to a method, device, equipment and storage medium for predicting oil and gas reservoir productivity. Background Art

[0002] With advances in oil and gas reservoir development technology, large-scale production has been achieved in shallow and medium-layer shale reservoirs. However, the production capacity prediction and production technology for deep shale reservoirs still need to be improved. Deep shale oil and gas resources are enormous and form the decisive resource foundation for future large-scale shale oil and gas production. In actual production, multi-stage fracturing horizontal well technology has become an effective means of commercial production due to the dense matrix and low permeability of deep shale reservoirs. Productivity is a key indicator for evaluating post-fracture development results. Therefore, pre-production production capacity prediction of deep shale reservoirs is crucial to ensuring development results.

[0003] Compared with shallow shale, deep shale has high in-situ stress and large stress differentials, a low brittleness index, and high construction pressures. This makes sand addition during fracturing difficult, and proppant distribution in the fractures difficult. Most proppant accumulates in the main fracture near the wellbore, leaving distal fractures severely closed. Furthermore, deep shale reservoirs have high fracture closure stresses, significantly increasing the probability of proppant breakage and embedding after fracturing, leading to closure of proppant fractures near the wellbore and a rapid decrease in fracture conductivity. Furthermore, deep shale reservoirs have more numerous and complex natural fractures, and the complex fracture network composed of both natural and artificial fractures is more sensitive to fracture stress, which can easily affect the productivity of deep shale reservoirs. Existing shale reservoir productivity prediction methods are primarily designed for shallow shale reservoirs using a single production system (fixed rate or fixed pressure) and are not suitable for deep shale reservoir productivity prediction. Therefore, an effective method for predicting the productivity of deep shale reservoirs is urgently needed. Summary of the Invention

[0004] The present application provides a method, apparatus, device and storage medium for predicting the productivity of oil and gas reservoirs, which are used to solve the problem of predicting the productivity of deep shale oil and gas reservoirs.

[0005] In a first aspect, the present application provides a method for predicting oil and gas reservoir productivity, comprising:

[0006] Obtaining the fracturing characteristics of the shale reservoir to be predicted;

[0007] Based on the fracturing characteristics, a physical model is constructed. The physical model includes the propped fracture area, the unpropped fracture area, the fractured inner area, the fractured outer area, and the unfractured area. The different areas are divided according to the proppant filling status in the fractures of the shale reservoir to be predicted and the effect after fracturing.

[0008] The seepage control equations of each region in the fixed-output production stage and the fixed-pressure production stage are coupled to obtain the seepage mathematical model. The fixed-output production stage is the stage where the production time is less than or equal to the critical production time, and the fixed-pressure production stage is the stage where the production time is greater than the critical production time.

[0009] The mathematical model of seepage is analytically solved to obtain the bottom hole pressure distribution and oil and gas reservoir production in real space pseudo-time corresponding to the shale reservoir to be predicted;

[0010] According to the bottom hole pressure distribution and oil and gas reservoir production in real space and pseudo time, the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in real space and real time are determined.

[0011] In one possible implementation, the mathematical model of seepage is analytically solved to obtain the bottom hole pressure distribution and oil and gas reservoir production in the real space pseudo-time corresponding to the shale reservoir to be predicted, including: through dimensionless processing, perturbation transformation, Laplace transform and Steifest numerical inversion, the mathematical model of seepage is analytically solved to obtain the bottom hole pressure distribution and oil and gas reservoir production in the real space pseudo-time corresponding to the shale reservoir to be predicted.

[0012] In one possible implementation, the seepage control equations of each region in the fixed-output production stage and the fixed-pressure production stage are coupled to obtain a seepage mathematical model, including: determining the initial conditions, internal and external boundary conditions of each region and the flow-pressure coupling conditions between different regions according to the production system, actual boundary conditions and the flow-pressure relationship between different regions, wherein the initial conditions include the pressures of each point in different regions at the initial moments in the fixed-output production stage and the fixed-pressure production stage; according to the initial conditions, internal and external boundary conditions of each region and the flow-pressure coupling conditions between different regions, the seepage control equations of each region in the fixed-output production stage and the fixed-pressure production stage are coupled to obtain a seepage mathematical model.

[0013] In one possible implementation, the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in real space and real time are determined based on the bottom hole pressure distribution and oil and gas reservoir production in real space pseudo time, including: using an iterative solution method to determine the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in the complete production stage in real space and real time based on the bottom hole pressure distribution and oil and gas reservoir production in real space pseudo time.

[0014] In one possible implementation, the iterative solution method in the oil and gas reservoir productivity prediction method includes:

[0015] Determine whether the first bottomhole pressure is less than the target bottomhole pressure. The first bottomhole pressure is the bottomhole pressure calculated according to the bottomhole pressure formula for the fixed production phase, at the first duration of the given production capacity forecast duration. The target bottomhole pressure is the bottomhole pressure at the end of the preset fixed pressure production phase.

[0016] If the first bottomhole pressure is less than the target bottomhole pressure, the bottomhole pressure during the fixed-rate production phase is equal to the first bottomhole pressure, the cumulative reservoir production is equal to the multiple of the first duration of the initial reservoir production, and the pressure of each region is obtained according to the pressure formula for each region during the fixed-rate production phase;

[0017] If the first bottom hole pressure is greater than or equal to the target bottom hole pressure, the bottom hole pressure in the constant pressure production stage is equal to the target bottom hole pressure. The cumulative oil and gas reservoir production is obtained by integrating the oil and gas reservoir production in the constant pressure production stage with time. The oil and gas reservoir production in the constant pressure production stage is obtained according to the oil and gas reservoir production formula in the constant pressure production stage. The pressure of each region is obtained according to the pressure formula of each region in the constant pressure production stage.

[0018] updating parameters of the seepage mathematical model based on the first bottom hole pressure and the pressure of each region in the fixed production phase or the target bottom hole pressure and the pressure of each region in the fixed pressure production phase, and determining whether the first duration is less than the production capacity prediction duration;

[0019] If so, the reservoir production and bottom hole pressure distribution during the complete production phase are output.

[0020] In one possible implementation, the seepage control equation in the oil and gas reservoir productivity prediction method is established in the following manner: based on the seepage, diffusion, slippage and supercritical adsorption and desorption effects of the shale reservoir to be predicted, the seepage control equations corresponding to the fractured inner zone, the fractured outer zone and the unfractured zone are established respectively; based on the pseudo-permeability modulus and stress sensitivity of the supported fracture zone and the unsupported fracture zone, the seepage control equations for the supported fracture zone and the unsupported fracture zone are established respectively.

[0021] In one possible implementation, the oil and gas reservoir productivity prediction method further includes: linearly flowing the fluid in the shale reservoir to be predicted, so as to set the flow characteristics of the fluid in each region when constructing the physical model.

[0022] In a second aspect, the present application provides an oil and gas reservoir productivity prediction device, comprising:

[0023] An acquisition module, used for acquiring the fracturing characteristics of the shale reservoir to be predicted;

[0024] A construction module is used to construct a physical model based on the fracturing characteristics. The physical model includes regions such as supported fracture areas, unsupported fracture areas, fractured inner areas, fractured outer areas, and unfractured areas. The different regions are divided according to the proppant filling conditions in the fractures of the shale reservoir to be predicted and the effects after fracturing.

[0025] The coupling module is used to couple the seepage control equations of each area in the fixed-output production stage and the fixed-pressure production stage to obtain a seepage mathematical model. The fixed-output production stage is the stage where the production time is less than or equal to the critical production time, and the fixed-pressure production stage is the stage where the production time is greater than the critical production time.

[0026] The analytical module is used to analytically solve the seepage mathematical model to obtain the bottom hole pressure distribution and oil and gas reservoir production in real space pseudo-time corresponding to the shale reservoir to be predicted;

[0027] The determination module is used to determine the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in real space and real time based on the bottom hole pressure distribution and oil and gas reservoir production in real space pseudo time.

[0028] In one possible implementation, the analytical module can be specifically used to analytically solve the seepage mathematical model through dimensionless processing, perturbation transformation, Laplace transform and Steifest numerical inversion, so as to obtain the bottom hole pressure distribution and oil and gas reservoir production under real space pseudo-time corresponding to the shale reservoir to be predicted.

[0029] In one possible implementation, the coupling module can be specifically used to: determine the initial conditions, internal and external boundary conditions of each region and the flow-pressure coupling conditions between different regions based on the production system, actual boundary conditions and the flow-pressure relationship between different regions, wherein the initial conditions include the pressures of each point in different regions at the initial moment in the fixed-production stage and the fixed-pressure production stage; according to the initial conditions, internal and external boundary conditions of each region and the flow-pressure coupling conditions between different regions, couple the seepage control equations of each region in the fixed-production stage and the fixed-pressure production stage to obtain a seepage mathematical model.

[0030] In one possible implementation, the determination module can be specifically used to: determine the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in the complete production stage in real space and real time by using an iterative solution method based on the bottom hole pressure distribution and oil and gas reservoir production in real space pseudo time.

[0031] In one possible implementation, the iterative solution method in the oil and gas reservoir productivity prediction device may include:

[0032] Determine whether the first bottomhole pressure is less than the target bottomhole pressure. The first bottomhole pressure is the bottomhole pressure calculated according to the bottomhole pressure formula for the fixed production phase, at the first duration of the given production capacity forecast duration. The target bottomhole pressure is the bottomhole pressure at the end of the preset fixed pressure production phase.

[0033] If the first bottomhole pressure is less than the target bottomhole pressure, the bottomhole pressure during the fixed-rate production phase is equal to the first bottomhole pressure, the cumulative reservoir production is equal to the multiple of the first duration of the initial reservoir production, and the pressure of each region is obtained according to the pressure formula for each region during the fixed-rate production phase;

[0034] If the first bottom hole pressure is greater than or equal to the target bottom hole pressure, the bottom hole pressure in the constant pressure production stage is equal to the target bottom hole pressure. The cumulative oil and gas reservoir production is obtained by integrating the oil and gas reservoir production in the constant pressure production stage with time. The oil and gas reservoir production in the constant pressure production stage is obtained according to the oil and gas reservoir production formula in the constant pressure production stage. The pressure of each region is obtained according to the pressure formula of each region in the constant pressure production stage.

[0035] updating parameters of the seepage mathematical model based on the first bottom hole pressure and the pressure of each region in the fixed production phase or the target bottom hole pressure and the pressure of each region in the fixed pressure production phase, and determining whether the first duration is less than the production capacity prediction duration;

[0036] If so, the reservoir production and bottom hole pressure distribution during the complete production phase are output.

[0037] In one possible implementation, the seepage control equation in the oil and gas reservoir productivity prediction device can be established in the following manner: based on the seepage, diffusion, slippage and supercritical adsorption and desorption of the shale reservoir to be predicted, the seepage control equations corresponding to the fractured inner zone, the fractured outer zone and the unfractured zone are established respectively; based on the pseudo-permeability modulus and stress sensitivity of the supported fracture zone and the unsupported fracture zone, the seepage control equations of the supported fracture zone and the unsupported fracture zone are established respectively.

[0038] In a possible implementation, the oil and gas reservoir productivity prediction device may further include: linear flow of fluid in the shale reservoir to be predicted, which is used to set the flow characteristics of the fluid in each area when the construction module constructs the physical model.

[0039] In a third aspect, the present application provides an electronic device comprising: a memory and a processor. The memory is used to store program instructions; the processor is used to call the program instructions in the memory to execute the oil and gas reservoir productivity prediction method of the first aspect.

[0040] In a fourth aspect, the present application provides a computer-readable storage medium, in which computer execution instructions are stored. When the computer execution instructions are executed, the oil and gas reservoir productivity prediction method of the first aspect is implemented.

[0041] In a fifth aspect, the present application provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, it is used to implement the oil and gas reservoir productivity prediction method of the first aspect.

[0042] The oil and gas reservoir productivity prediction method, device, equipment and storage medium provided in the present application obtain the fracturing characteristics of the shale reservoir to be predicted; construct a physical model based on the fracturing characteristics, and the physical model includes regions such as supported fracture area, unsupported fracture area, fracturing transformation inner area, fracturing transformation outer area and unfractured transformation area, wherein different areas are divided according to the proppant filling conditions in the fractures of the shale reservoir to be predicted and the effectiveness after fracturing; couple the seepage control equations of each area in the fixed production stage and the fixed pressure production stage to obtain a seepage mathematical model, the fixed production stage is a stage in which the production time is less than or equal to the critical production time, and the fixed pressure production stage is a stage in which the production time is greater than the critical production time; analytically solve the seepage mathematical model to obtain the bottom hole pressure distribution and oil and gas reservoir production under real space pseudo-time corresponding to the shale reservoir to be predicted; determine the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in real space and real time based on the bottom hole pressure distribution and oil and gas reservoir production under real space pseudo-time. Among them, the impact of variable production system, incomplete fracture support, and fracture closure on oil and gas reservoir production is comprehensively considered, which is more in line with actual production conditions and can improve the accuracy of production capacity prediction; at the same time, the use of analytical solution method has faster calculation speed and is more conducive to practical application. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0044] Figure 1 This is a schematic diagram of an application scenario provided by an embodiment of the present application;

[0045] Figure 2 This is a flow chart of a method for predicting oil and gas reservoir productivity provided by an embodiment of the present application;

[0046] Figure 3 This is a schematic diagram of a physical model provided by an embodiment of the present application;

[0047] Figure 4 is a schematic diagram of an iterative solution method provided in one embodiment of the present application;

[0048] Figure 5 This is a comparison chart of the production capacity prediction results provided by an embodiment of the present application and the prediction results of commercial numerical simulation software;

[0049] Figure 6This is a schematic diagram of the impact of fracture stress sensitivity on shale oil and gas reservoir production provided by an embodiment of the present application;

[0050] Figure 7 This is a schematic diagram of the effect of the initial oil and gas reservoir production on the shale oil and gas reservoir production during the fixed production phase provided by one embodiment of the present application;

[0051] Figure 8 This is a schematic diagram of the effect of bottom hole flowing pressure on shale oil and gas reservoir production during a constant pressure production phase provided by an embodiment of the present application;

[0052] Figure 9 This is a schematic diagram of the effect of propped fracture half-length on shale gas production provided by an embodiment of the present application;

[0053] Figure 10 This is a schematic structural diagram of an oil and gas reservoir productivity prediction device provided in one embodiment of the present application;

[0054] Figure 11 It is a structural diagram of an electronic device provided in one embodiment of the present application.

[0055] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0056] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0057] The terms "first", "second" etc. in the specification and claims of the present application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable in appropriate circumstances, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, the process, system, product or equipment comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or that are inherent to these processes, products or equipment.

[0058] First, some technical terms involved in this application are explained:

[0059] Closed boundary: A boundary where the velocity component of the fluid in the direction normal to the boundary is zero. If there is no fluid flow at the boundary, there is no energy replenishment at the boundary. As the reservoir is developed, the pressure at the boundary will gradually decrease.

[0060] Constant pressure boundary: refers to the pressure at which the boundary of the oil and gas reservoir is set to a fixed value, usually connected to a water body or replenishing energy.

[0061] In related technologies, shale oil and gas reservoir productivity prediction methods mostly assume that the proppant is completely filled in the fractures when dealing with the complex fracture network formed after fracturing, and do not consider the effects of incomplete fracture support and fracture closure. Among them, far-well propped fractures are due to the failure of proppant to fill and close, and near-well propped fractures are due to the rapid drop in pressure during production, resulting in a large pressure difference, which causes the proppant to break or embed and cause the fracture closure. Moreover, they are only based on a single production system (fixed-rate production or fixed-pressure production), and do not consider the impact of changes in the working system during the actual production process, resulting in low accuracy of shale oil and gas reservoir productivity prediction results.

[0062] In response to the above problems, this application proposes a method for predicting the productivity of oil and gas reservoirs. This method constructs a physical model and processes the complex fracture network formed after fracturing in different regions. It takes into account the problem of partial filling of proppant in the fracture and the closure of the fracture, which leads to a decrease in the conductivity of the fracture. In combination with actual production characteristics (such as the length of the fractured horizontal well, the number of fracture stages and porosity, etc.), a variable production method is adopted. That is, the complete production stage is divided into a fixed production stage and a fixed pressure production stage. Given the external boundary conditions (fixed pressure boundary or closed boundary) and the internal boundary conditions (fixed production or fixed pressure production), a mathematical model of seepage is established, and then solved by an analytical solution method to obtain the oil and gas reservoir production and pressure distribution of the fractured horizontal well in the shale oil and gas reservoir. Because this method takes into account the effects of variable production, incomplete fracture support and fracture closure on oil and gas reservoir production, it is more in line with actual production conditions and can improve the accuracy of productivity prediction. At the same time, the analytical solution method has a faster calculation speed and is more conducive to practical application.

[0063] Figure 1 This is a schematic diagram of an application scenario provided by an embodiment of the present application. Figure 1As shown, this application scenario includes a client 11 and a server 12, wherein the number of clients 11 can be at least one. In practical applications, the fracturing characteristics of the shale reservoir can be obtained by the client 11 and stored in the server 12. The server 12 can construct a physical model corresponding to the shale reservoir based on the fracturing characteristics, and divide the physical model into different regions based on the proppant filling status in the fractures of the shale reservoir and the effect after fracturing. At the same time, combined with the variable production mode, the seepage control equations for different regions at different production stages are obtained, and the seepage control equations are coupled to obtain a seepage mathematical model. Then, through analytical and iterative solution methods, the oil and gas reservoir production and bottomhole pressure distribution of the shale reservoir in real space and real time are obtained.

[0064] It should be noted that server 12 can also be replaced by a server cluster or other computing device with sufficient computing power. Client 11 can be a computer, laptop, or personal digital assistant (PDA). In addition, the oil and gas reservoir productivity prediction method provided in this application can also be used to predict the productivity of mines or coalbed methane reservoirs developed using multi-stage horizontal well fracturing technology.

[0065] The following combination Figure 1 For application scenarios, refer to Figure 2 To describe the oil and gas reservoir productivity prediction method according to the exemplary embodiment of the present application. It should be noted that the above application scenario is only shown to facilitate understanding of the spirit and principle of the present application, and the implementation of the present application is not affected by Figure 1 Limitations of the application scenario shown.

[0066] Figure 2 FIG. 1 is a flow chart of a method for predicting oil and gas reservoir productivity provided by an embodiment of the present application. Figure 2 As shown, the oil and gas reservoir productivity prediction method in the embodiment of the present application includes the following steps:

[0067] S201: Acquire the fracturing characteristics of the shale reservoir to be predicted.

[0068] The shale reservoirs to be predicted may include medium-shallow shale reservoirs and deep shale reservoirs.

[0069] In practice, shale reservoirs typically exhibit different fracturing characteristics after fracturing, including post-fracture fracture shape, fracture distribution, and proppant distribution within the fractures. Proppants are key materials for extracting oil and gas from shale reservoirs. They are carried into the shale reservoir by the fracturing fluid and supported within the fractures of the fractured shale reservoir, effectively directing oil and gas into the wells, significantly increasing production and extending the life of the wells.

[0070] In addition, some natural fractures will be formed in the natural evolution process of the predicted shale reservoir, and artificial fractures will be formed after fracturing construction during oil and gas extraction. Therefore, when extracting oil and gas, natural fractures and artificial fractures together constitute a complex fracture network.

[0071] S202: Construct a physical model based on the fracturing characteristics. The physical model includes supported fracture areas, unsupported fracture areas, inner fractured areas, outer fractured areas, and unfractured areas. The different areas are divided based on the proppant filling conditions in the fractures of the shale reservoir to be predicted and the effects after fracturing.

[0072] In this step, a physical model can be constructed by numerical simulation methods or programming software (such as MATLAB).

[0073] For example, the complex fracture network formed after the shale reservoir to be predicted is equivalent to a fractured body, that is, according to the fracture characteristics, a physical model corresponding to the shale reservoir to be predicted after fracture is constructed. At the same time, according to the proppant filling condition in the fracture and the effect of the shale reservoir to be predicted after fracture, the physical model is divided into supported fracture area 1, unsupported fracture area 2, fractured inner area 3, fractured outer area 4 and unfractured area 5, etc. Figure 3 shown.

[0074] The propped fracture zone 1 refers to the area near the wellbore after fracturing, consisting of proppant-filled fractures. The inner fracture zone 3 refers to the complex fracture network formed by propped fractures. This area has a high degree of fracturing and a significant increase in permeability. The unpropped fracture zone 2 refers to the fracture area in the far-flung area where proppant cannot reach. The outer fracture zone 4 refers to the fracture network formed by unpropped fractures. Although the fracturing effect in this area is not as good as that in the inner fracture zone, it is still a fracture-effective area, with a permeability higher than that of the original reservoir. The unfractured fracture zone 5 refers to the original reservoir, which has not been fracturing-treated.

[0075] In some embodiments, the shale reservoir to be predicted can be fractured by using a multi-stage fracturing horizontal well technology, which will form multiple fracturing areas after fracturing. Figure 3 The figure shows only three fracturing zones for reference; in practice, more zones can be fractured. Each fracturing zone includes the original reservoir, a stimulated zone, and a fracture zone. The original reservoir includes an unfractured stimulated zone 5; the stimulated zone includes an inner fracture zone 3 and an outer fracture zone 4; and the fracture zone includes a propped fracture zone 1 and an unpropped fracture zone 2.

[0076] Furthermore, the fractures in propped fracture zone 1 are also referred to as "near-wellbore supported fractures," and the fractures in unpropped fracture zone 2 are also referred to as "far-wellbore unpropped fractures." During actual oil and gas reservoir production, fracture closure is important, and the closure causes of "near-wellbore supported fractures" and "far-wellbore unpropped fractures" differ. Specifically, "far-wellbore unpropped fractures" close due to a lack of proppant filling, while "near-wellbore supported fractures" close due to a rapid pressure drop during production, resulting in a large production pressure differential, which causes the proppant to break or embed into the formation.

[0077] During the production of shale oil and gas reservoirs, the effective stress within the fractures increases due to a decrease in reservoir pressure, leading to gradual closure of the fractures. The conductivity of both "near-well supported fractures" and "far-well unsupported fractures" decreases, but "far-well unsupported fractures" are more stress sensitive. Therefore, when predicting oil and gas reservoir productivity, it is necessary to consider different stress sensitivity coefficients for "near-well supported fractures" and "far-well unsupported fractures," depending on the actual situation. Stress sensitivity is a characteristic of the rock itself that causes it to react significantly to specific forms of external forces. For example, strata are very sensitive to parallel forces, and even very small forces can destroy the entire bonded layer. Shale, on the other hand, is sensitive to both parallel and perpendicular forces. Reservoir pressure includes the pressure in each region and the bottomhole pressure (or bottomhole flowing pressure).

[0078] Furthermore, in response to the problem of ignoring incomplete support of fractures in existing shale oil and gas reservoir productivity prediction methods, the method provided in this application takes into account the impact of incomplete filling of proppants in fractures. Therefore, it is possible to quantitatively distinguish the contribution of "supported fractures near the wellbore" and "unsupported fractures far from the wellbore" to the oil and gas reservoir productivity, thereby ensuring the accuracy of the oil and gas reservoir productivity prediction.

[0079] exist Figure 3 In the fracking area, a coordinate system is established, where O represents the origin of the coordinate system, and xy represents the direction of the coordinate system. xy can be interchanged. The cracks after fracking are equal in length and symmetrical in the vertical direction. e represents the half length of the cluster spacing after fracturing, y e represents the half-width of the fracture section of deep shale reservoir, x oF represents the total crack half-length, which is the sum of the supported crack half-length and the unsupported crack half-length, x IF represents the half-length of the support crack, ω IF and ω oF denote the crack width of the supported crack and the crack width of the unsupported crack, ω IF / 2 and ω oF / 2 represents the half-width of a supported fracture and the half-width of an unsupported fracture, respectively. Furthermore, in the field of oil and gas reservoir development, wells are typically fractured into several segments, each of which is then divided into smaller "clusters." Close cluster spacing increases the number of reservoir fractures, enhances fluid inflow, and increases the stimulated volume, facilitating subsequent recovery.

[0080] in addition, Figure 3 The arrows in different regions indicate the flow direction of the fluids in those regions. The fluid in the inner fracture zone 3 flows toward the propped fracture zone 1, the fluid in the outer fracture zone 4 flows toward the unpropped fracture zone 2, and the fluid in the unfractured fracture zone 5 flows toward the outer fracture zone 4. The fluids include oil and natural gas.

[0081] Corresponding to the above embodiment, the shale reservoirs within each region can be considered as homogeneous reservoirs, and the reservoir physical parameters of different regions are different. Each region can be coupled through flow and pressure conditions. Among them, the reservoir physical parameters include porosity and permeability.

[0082] S203: The seepage control equations of each region in the fixed-output production stage and the fixed-pressure production stage are coupled to obtain a seepage mathematical model. The fixed-output production stage is a stage in which the production time is less than or equal to the critical production time, and the fixed-pressure production stage is a stage in which the production time is greater than the critical production time.

[0083] In actual conditions, as the cumulative production of oil and gas reservoirs increases, the oil and gas reservoirs in deep shale reservoirs decrease, and accordingly, the pressure in oil and gas wells will also decrease, resulting in an increase in the pressure difference between the inside and outside of the oil and gas wells, which can easily cause damage to the deep shale reservoirs, and thus lead to a decrease in oil and gas reservoir production. In order to be more in line with the actual development (or production) situation of oil and gas reservoirs and to increase oil and gas reservoir production, the method provided in this application divides the entire oil and gas reservoir production stage into a fixed-production production stage and a fixed-pressure production stage, that is, a transition from a fixed-production production mode to a fixed-pressure production mode. Among them, in the fixed-production production stage, the oil and gas reservoir production of each exploitation is fixed; in the fixed-pressure production stage, the oil and gas reservoir production or bottom hole flow pressure of each exploitation is fixed.

[0084] In this step, the critical production time τ c The production duration of the fixed production stage and the fixed pressure production stage can be determined according to actual conditions and is not restricted here.

[0085] The method provided by this application, when the production time t≤τ c At a fixed gas production rate q sc Production, that is, the fixed production stage; when t>τ c When the bottom hole pressure p is constant wfProduction, namely the constant-pressure production stage. To address the problem that existing shale oil and gas reservoir capacity prediction methods ignore changes in working systems during the production process, the method provided in this application considers the changing relationship between oil and gas reservoir output and pressure during the transition from a fixed-rate production mode to a fixed-pressure production mode. This method is more realistic than a single production system (considering only fixed-rate production or fixed-pressure production), and the oil and gas reservoir capacity prediction results will also be more accurate.

[0086] Furthermore, the governing equations for seepage flow in each region are formally the same during the fixed-rate and fixed-pressure production phases, but the initial boundary conditions differ. Furthermore, due to the different pressures during the fixed-rate and fixed-pressure production phases, pressure-related parameters, such as permeability, vary across production phases. Other parameters unrelated to pressure, such as horizontal well length and reservoir thickness, remain the same across production phases.

[0087] Furthermore, since the seepage control equations in different regions are different (the specific seepage control equations can be referred to the following embodiments), in order to obtain the total oil and gas reservoir production in the complete production stage, that is, the fixed production stage and the fixed pressure production stage, and to ensure that the seepage control equations are solvable, it is necessary to establish flow pressure coupling conditions, initial conditions, and internal and external boundary conditions between each region, so as to couple the seepage control equations of different regions in different production stages and obtain the coupled seepage control equations, that is, the seepage mathematical model.

[0088] S204: Analytically solving the seepage mathematical model to obtain the bottom hole pressure distribution and oil and gas reservoir production in real space pseudo-time corresponding to the shale reservoir to be predicted.

[0089] In this step, pseudo-time is relative to real time. When solving the mathematical model for seepage, introducing pseudo-time can address nonlinear factors within the model, specifically the nonlinearity caused by changes in parameters such as the comprehensive compressibility coefficient with pressure. After solving for the bottomhole pressure distribution and reservoir production in real-space pseudo-time, they are mapped back to real space and real time using the corresponding formulas. The specific process is described in the following examples.

[0090] In some embodiments, semi-analytical and numerical methods can be used to solve the seepage mathematical model to obtain the real-space pseudo-time bottomhole pressure distribution and oil and gas reservoir production corresponding to the predicted shale reservoir. However, compared with semi-analytical and numerical methods, analytical methods are simpler, faster, and more convenient for application in oil and gas reservoir development, such as in mines.

[0091] S205: Determine the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in real space and real time based on the bottom hole pressure distribution and oil and gas reservoir production in real space pseudo time.

[0092] Based on the above embodiment, it can be seen that in this step, the bottomhole pressure distribution and oil and gas reservoir production in real space and pseudo time are mapped to the bottomhole pressure distribution and oil and gas reservoir production in real space and real time. For example, this can be achieved through an analytical solution method, and the details are shown in the following embodiment.

[0093] The oil and gas reservoir productivity prediction method provided in the embodiments of this application divides the constructed physical model into different regions based on the proppant filling status in the fractures of the predicted shale reservoir and the effectiveness of the fractures. This method fully considers the impact of incomplete fracture propping and fracture closure on oil and gas reservoir production. At the same time, it also considers the transition of the production system from a fixed-rate production mode to a fixed-pressure production mode. This method is more in line with actual production conditions than a single production system, and the resulting oil and gas reservoir productivity prediction results will also be more accurate. In addition, the use of an analytical solution method has faster calculation speed and is more conducive to practical application.

[0094] In some embodiments, a mathematical model of seepage is analytically solved to obtain the bottomhole pressure distribution and oil and gas reservoir production in real-space pseudo-time corresponding to the shale reservoir to be predicted, including: analytically solving the mathematical model of seepage to obtain the bottomhole pressure distribution and oil and gas reservoir production in real-space pseudo-time corresponding to the shale reservoir to be predicted through dimensionless processing, perturbation transformation, Laplace transform, and Stehfest numerical inversion. Dimensionless processing is to reduce parameters with units to dimensionless parameters; perturbation transformation is required to consider the stress sensitivity of fractures; when solving the mathematical model of seepage, the model after dimensionless processing and perturbation transformation can be Laplace transformed and then solved in Laplace space; finally, the Stehfest method is used to invert the numerical values obtained by Laplace transform to obtain the bottomhole pressure distribution and oil and gas reservoir production in real-space pseudo-time.

[0095] For example, the mathematical model of seepage in a propped fracture zone is used to illustrate the analytical solution steps. First, dimensionless variables are introduced, including dimensionless pseudo-pressure, dimensionless pseudo-time, dimensionless propped fracture half-length, and dimensionless unpropped fracture half-length. Dimensionless pseudo-pressure and dimensionless pseudo-time correspond to true pressure and true time, respectively.

[0096] Among them, the dimensionless pseudo-pressure in the fixed production stage and the fixed pressure production stage are:

[0097]

[0098] The dimensionless pseudo-time in the fixed output production stage and the fixed pressure production stage are:

[0099]

[0100] The dimensionless propped crack half-length, dimensionless crack half-length, dimensionless propped crack width, dimensionless unpropped crack width, dimensionless fracture section half-width and dimensionless outer boundary distance are:

[0101]

[0102] Among them, L r Indicates the reference length, η r Indicates the reference pressure coefficient, which is a fixed reference value and can be selected according to actual conditions. IF represents the permeability of the supported fracture zone, H represents the effective thickness of the reservoir, ψ represents the pseudo-pressure, and ψ i represents the pseudo-pressure corresponding to the original formation pressure, ψ wf The bottom hole pressure is p wf The corresponding pseudo-pressure, q sc Indicates gas production, μ g Indicates gas viscosity, B g Indicates the gas volume coefficient. a represents pseudo-time, and the subscript D indicates dimensionless processing.

[0103] The permeabilities of the dimensionless fracturing inner zone, dimensionless fracturing outer zone, dimensionless unfractured zone, dimensionless propped fracture zone, and dimensionless unpropped fracture zone are:

[0104]

[0105] Among them, k Ima 、k oma 、k ma 、k IF and k oF k represents the permeability of the inner zone of the fractured zone, the outer zone of the fractured zone, the unfractured zone, the propped fracture zone, and the unpropped fracture zone, respectively; r Indicates the reference permeability, which is a fixed reference value, such as k r It can take the value k oma wait.

[0106] The pseudo-permeability moduli of the dimensionless supported fracture region and the dimensionless unsupported fracture region are:

[0107] γ IFD =(ψ i -ψ wf )γ IF and γ oFD =(ψ i -ψ wf )γ oF .

[0108] Among them, γ IF and γ oFdenote the pseudo-permeability moduli of the propped fracture zone and the unpropped fracture zone, respectively.

[0109] The mass transfer coefficients of the dimensionless unsupported fracture zone, dimensionless supported fracture zone, and dimensionless unfractured stimulation zone are:

[0110]

[0111] The pressure conductivity coefficients η (or pressure transmission coefficients) of the dimensionless fracturing inner zone, dimensionless fracturing outer zone, dimensionless unfractured zone, dimensionless propped fracture zone, and dimensionless unpropped fracture zone are:

[0112]

[0113] Where η r Indicates the reference pressure coefficient, which is a fixed reference value and can be selected according to actual conditions. Im represents the porosity of the inner zone of the fracture stimulation, c tIm represents the comprehensive compression coefficient of the inner zone of the fracture stimulation. The subscripts m, om, Im, oF, and IF represent the unfractured stimulation area, the outer zone of the fracture stimulation, the inner zone of the fracture stimulation, the unpropped fracture area, and the propped fracture area, respectively. φ and c t represent porosity and comprehensive compressibility, respectively, but the subscripts are different in different regions.

[0114] Optionally, after the mathematical model of seepage is dimensionless, the nonlinearity caused by the stress sensitivity of the fracture can be processed through perturbation transformation. The mathematical model of seepage after perturbation transformation can be expressed as follows in the fixed production stage:

[0115]

[0116] In the constant pressure production stage, it can be expressed as:

[0117]

[0118] Among them, the first equation in the above two seepage mathematical models represents the seepage control equation, the second equation represents the initial condition, the third and fourth equations represent the flow-pressure conditions of regional coupling, and the fifth equation represents the internal boundary condition.

[0119] In the above two seepage mathematical models represents the second-order partial derivative calculation of the pressure in the supporting crack zone during the fixed production stage after the perturbation transformation, represents the pressure in the unsupported fracture zone during the fixed production stage after perturbation transformation, ζ IF represents the pressure in the supporting fracture zone during the constant pressure production stage after perturbation transformation, ζ IF1D represents the pressure at the end of the fixed production stage after perturbation transformation, ζoF represents the pressure in the unsupported fracture zone during the constant pressure production phase after perturbation transformation, w IFD represents the dimensionless support crack width, w oFD represents the dimensionless unsupported crack width, where ω and w represent the same parameter.

[0120] On the basis of the above embodiment, the percolation mathematical model after dimensionless processing and perturbation transformation is subjected to Laplace transformation, and then solved in Laplace space.

[0121] Specifically, under the pull-type space, the pressures of the unfractured zone, the fractured outer zone, the fractured inner zone, the unpropped fracture zone, and the propped fracture zone during the fixed production stage are:

[0122]

[0123]

[0124]

[0125] and

[0126] in:

[0127]

[0128]

[0129]

[0130]

[0131]

[0132] Where cosh represents the hyperbolic cosine function, sinh represents the hyperbolic sine function, and tanh represents the hyperbolic tangent function. α is the tangential momentum coordination coefficient, and different subscripts correspond to different regions. s represents the parameter in the Laplace transform, and its value can be determined based on actual conditions.

[0133] Under the pull-type space, the bottom hole flowing pressure in the fixed production stage is:

[0134]

[0135] In addition, under the pull-type space, the pressures of the unfractured zone, the fractured outer zone, the fractured inner zone, the unsupported fracture zone, and the supported fracture zone during the constant pressure production stage are:

[0136]

[0137]

[0138]

[0139] and

[0140] in:

[0141]

[0142]

[0143] in:

[0144]

[0145]

[0146]

[0147] Where, ψ IF1D represents the pseudo-pressure in the propped fracture zone after dimensionless processing, perturbation transformation, and Laplace transform during the constant-pressure production stage. Correspondingly, different subscripts represent the pseudo-pressure in different regions after dimensionless processing, perturbation transformation, and Laplace transform.

[0148] In the pull-type space, the gas production in the constant pressure production stage is:

[0149] The oil and gas reservoir production is

[0150] Finally, the Steifest method can be used to invert the values obtained by Laplace transform to obtain the oil and gas reservoir production in real space pseudo-time:

[0151]

[0152] The bottom hole pressure distribution is:

[0153]

[0154]

[0155] Here, ! represents factorial, and the value range of k is [(i+1) / 2, min(i, N / 2)].

[0156] Where ∑ is the summation symbol, represents the bottom hole pressure distribution in the pull space, i represents the production time, the value range is [1, N], N represents the end time of production, t aDrepresents the pseudo-time after dimensionless processing, t D Represents the production time after dimensionless processing.

[0157] When production time t≤τ c hour, When t>τ c hour,

[0158] Based on the above examples, the method provided in the application can obtain an analytical solution for the productivity of deep shale oil and gas reservoirs through dimensionless processing, perturbation transformation, Laplace transform, and Steifest numerical inversion. Specifically, it can obtain the reservoir production and bottomhole pressure distribution. Compared with semi-analytical and numerical solutions, the method provided in the application is simpler and faster, making it more convenient to apply to oil and gas reservoir development in mines and other fields.

[0159] In addition, in addition to constructing the seepage control equation based on existing flow mechanisms, such as slippage, adsorption-desorption, and stress sensitivity, if a new flow mechanism emerges, the method provided in the application will also make it easier to consider adding the new flow mechanism to the seepage control equation.

[0160] In some embodiments, the seepage control equations in the oil and gas reservoir productivity prediction method can be established in the following manner: based on the seepage, diffusion, slippage, and supercritical adsorption and desorption of the shale reservoir to be predicted, the seepage control equations corresponding to the fractured inner zone, the fractured outer zone, and the unfractured zone are respectively established; based on the pseudo-permeability modulus and stress sensitivity of the propped fracture zone and the unpropped fracture zone, the seepage control equations for the propped fracture zone and the unpropped fracture zone are respectively established. In this case, the unfractured zone, the fractured outer zone, and the fractured inner zone can be regarded as a matrix system, and the propped fracture zone and the unpropped fracture zone can be regarded as a fracture system.

[0161] For example, the steps for constructing the seepage control equation in the matrix system are explained by taking the unfractured zone as an example. First, considering the seepage, diffusion, slippage, and supercritical adsorption and desorption of the fluid in the matrix system, the seepage control equation can be expressed as:

[0162]

[0163] Where, is the vector differential operator, ρ gm is the gas density of the unfractured zone, v m is the seepage velocity of the matrix system, q am represents the adsorbed gas desorption rate, q m-m is the gas exchange between matrix systems, φ m is the porosity of the unfractured zone, t represents time, Is the partial differential symbol. In the unfractured zone and the fractured zone, there is no gas inflow, so q m-m = 0; for the outer zone of the fracturing transformation, there is gas supply from the unfractured transformation zone, so

[0164]

[0165] Where, subscripts m and om represent the unfractured zone and the non-fractured zone, respectively, and k ma is the permeability of the unfractured zone, μ gm is the gas viscosity of the unfractured zone, x oF is the total crack half length. In actual situations, when x=x oF When q m-om The value of .

[0166] Among them, the matrix system seepage velocity v m for:

[0167]

[0168] Where k is the permeability, k m is the permeability of the matrix system, R is the ideal gas constant, T is the reservoir temperature, M is the gas molar mass, C gm is the gas compressibility coefficient of the matrix system, p m is the pressure of the matrix system, α is the tangential momentum coordination coefficient, Indicates that p m Perform vector differentiation.

[0169] Among them, the adsorbed gas desorption rate q am for:

[0170]

[0171] Where B gm is the gas volume coefficient of the matrix system, V L is the Langmuir volume, p L is the Langmuir pressure, ρ am is the density of the adsorbed phase.

[0172] Then, pseudo-pressure and pseudo-time can be introduced to deal with the nonlinearity caused by the change of gas physical parameters, such as gas density and reservoir temperature, with pressure.

[0173] Where, the pseudo pressure ψ m for:

[0174]

[0175] Where Z is the ideal gas deviation factor and ∫ is the integration symbol.

[0176] Pseudo-time t am for:

[0177]

[0178] Where c tm represents the comprehensive compression coefficient of the matrix system, and the subscript i represents the production moment.

[0179] Among them, the matrix system comprehensive compressibility coefficient c tm =c m +c gm +c dm , where c m and C gm are respectively the matrix pore compressibility coefficient and the matrix system gas compressibility coefficient, both of which are known values, c dm is the supercritical desorption compressibility coefficient, which can be obtained by get.

[0180] Based on the above embodiment, during one-dimensional isothermal fluid flow, the flow control equations for the unfractured zone, the fractured outer zone, and the fractured inner zone are obtained as follows:

[0181]

[0182]

[0183]

[0184] Corresponding to the above embodiment, the steps of establishing the seepage control equation in the fracture system are explained by taking the unsupported fracture area as an example.

[0185] Since only free gas exists in the unsupported fracture system, it is possible to consider supplying the gas from the matrix system to the fracture system, and then the seepage control equation of the fracture system is obtained as follows:

[0186]

[0187] Where, ρ goF is the gas density in the unsupported crack region, v oF is the seepage velocity of the fracture system, q om-oF is the gas exchange volume between the outer zone of the fracturing stimulation and the unsupported fractures, φ oF is the fracture porosity.

[0188] The seepage velocity of the fracture system is:

[0189]

[0190] The gas exchange rate between the outer zone of the fracturing stimulation and the unsupported fracture is:

[0191]

[0192] Where, ω oF is the crack width of the unsupported crack, p oF represents the pressure in the unsupported crack zone, p om Indicates the pressure in the outer zone of the fracturing stimulation.

[0193] In addition, the seepage equation can be linearized using pseudo-pressure and pseudo-time, and the pseudo-permeability modulus can be introduced to characterize the change of permeability in the unsupported fracture area with pressure. The formulas for pseudo-pressure and pseudo-time in the fracture system can refer to the above-mentioned embodiments of the matrix system. In specific use, the corresponding parameters can be selected according to the matrix system and the fracture system. For example, the matrix system comprehensive compressibility coefficient c in the matrix system is tm , in the fracture system is the comprehensive compression coefficient of the fracture system c toF .

[0194] Comprehensive compression coefficient of the crack system c toF for:

[0195] c toF =c oF +c goF .

[0196] Where c oF is the fracture pore compression coefficient, which can be determined by conducting indoor physical experiments on field core samples. The actual measurement is of the entire rock sample, reflecting the compression coefficient of the corresponding oil and gas reservoir; c goF is the gas compression coefficient of the fracture system, which can be calculated by empirical formula based on the pressure in different areas.

[0197] For example, the compression coefficients of different regions can be given according to the characteristics of different regions considered when partitioning the physical model and in combination with the compression coefficients of actual oil and gas reservoirs.

[0198] Permeability k of the unsupported fracture zone oF for:

[0199]

[0200] Where, γ oF is the pseudo-permeability modulus of the unsupported fracture zone, ψ i is the pseudo-pressure corresponding to the original formation pressure, ψ oF is the pseudo-pressure corresponding to the pressure in the unpropped fracture zone, and e is the base of the natural logarithm function. The permeability of the propped fracture zone can be obtained by referring to the permeability of the unpropped fracture zone.

[0201] Furthermore, the seepage control equations in the unsupported fracture zone and the supported fracture zone can be obtained as follows: and

[0202] Wherein, the subscripts oF and IF represent the unsupported fracture area and the supported fracture area, respectively, and γ IF is the pseudo-permeability modulus of the supported fracture zone.

[0203] In some embodiments, the seepage control equations of each region in the fixed production stage and the fixed pressure production stage are coupled to obtain a seepage mathematical model, including: determining the initial conditions, internal and external boundary conditions of each region and the flow-pressure coupling conditions between different regions according to the production system, actual boundary conditions and the flow-pressure relationship between different regions, wherein the initial conditions include the pressures of each point in different regions at the initial moment in the fixed production stage and the fixed pressure production stage; according to the initial conditions, internal and external boundary conditions of each region and the flow-pressure coupling conditions between different regions, the seepage control equations of each region in the fixed production stage and the fixed pressure production stage are coupled to obtain a seepage mathematical model. Among them, the production system includes fixed production and fixed pressure production. The actual boundary conditions include the fluid in the inner zone of the fracturing transformation flowing to the supported fracture zone, the fluid in the outer zone of the fracturing transformation flowing to the unsupported fracture zone, the fluid in the unfractured transformation zone flowing to the outer zone of the fracturing transformation, etc.

[0204] For example, in order to ensure that the seepage control equation obtained in the above embodiment is solvable, flow-pressure coupling conditions, initial conditions, and internal and external boundary conditions between different regions can be established based on the production system, actual boundary conditions, and the flow-pressure relationship between different regions.

[0205] Among them, the flow and pressure coupling conditions between each area are:

[0206] The flow rate and pressure at the junction of the outer zone of the fracturing stimulation and the unsupported fracture zone are continuous. The flow rate and pressure coupling condition at the junction of the outer zone of the fracturing stimulation and the unsupported fracture zone is:

[0207] When y=w oF / 2,

[0208] The flow rate and pressure at the junction of the inner zone of the hydraulic fracturing stimulation and the propped fracture zone are continuous. The flow rate and pressure coupling condition at the junction of the inner zone of the hydraulic fracturing stimulation and the propped fracture zone is:

[0209] When y=w IF / 2,

[0210] The flow and pressure at the junction of the unsupported fracture zone and the supported fracture zone are continuous. Then the flow and pressure coupling condition at the junction of the unsupported fracture zone and the supported fracture zone is:

[0211] At x=x IF hour, After performing partial derivative operation, we get

[0212] In addition, the initial conditions are: in the fixed production stage (stage I), that is, t≤τ c When producing oil and gas at a fixed gas production rate, the initial pressure of each point in the unfractured zone, the fractured outer zone, the fractured inner zone, the unsupported fracture zone, and the supported fracture zone is equal to the pseudo-pressure ψ corresponding to the original formation pressure. i , which can be expressed as:

[0213]

[0214] In the constant pressure production stage (stage II), t>τ c When producing oil and gas at a constant bottomhole flowing pressure, the initial pressures at each point in the unfractured zone, the fractured outer zone, the fractured inner zone, the unpropped fracture zone, and the propped fracture zone are equal to the pressures of each zone at the end of stage I, which can be expressed as:

[0215]

[0216]

[0217] Combine Figure 3 , the unfractured zone is at x=x e The closed area, the outer area of the fracturing transformation and the inner area of the fracturing transformation are at y=y e The closed, unsupported crack zone is at x = x oF If the fracture is closed, the outer boundary conditions of the unfractured zone, the outer fractured zone, the inner fractured zone, and the unsupported fracture zone can be expressed as follows:

[0218]

[0219] The inner boundary conditions are:

[0220] At t≤τ c When the horizontal well has a constant gas production rate q sc Production, the oil and gas reservoir production under pseudo time is:

[0221]

[0222] When t>τ c When the horizontal well is at a constant bottom hole pressure p wf Production, the bottom hole pressure under the pseudo time is:

[0223] ψ IF (x, t a )| x＝0 =ψwf .

[0224] Based on the above embodiments, it can be seen that the method provided in this application comprehensively considers the seepage, diffusion, slippage, supercritical adsorption and desorption of oil and gas in deep shale, the stress sensitivity of incomplete support of fractures, supported fractures and unsupported fractures, and the impact of changes in working systems during the production process on the production capacity of shale oil and gas reservoirs. It is more in line with on-site fracturing and production conditions, and provides more accurate theoretical guidance for accurately calculating the production of deep shale oil and gas reservoirs and evaluating the fracturing effect.

[0225] In some embodiments, determining the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in real space and real time based on the bottom hole pressure distribution and oil and gas reservoir production in real space pseudo time may include: using an iterative solution method to determine the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in the complete production stage in real space and real time based on the bottom hole pressure distribution and oil and gas reservoir production in real space pseudo time.

[0226] In the above embodiment, the pseudo-time and pseudo-pressure are functions related to pressure. If the gas volume (or gas production) of the oil and gas reservoir in real time is to be obtained, an iterative solution method is required.

[0227] Specifically, the iterative solution method in the oil and gas reservoir productivity prediction method may include: judging whether the first bottom hole pressure is less than the target bottom hole pressure, the first bottom hole pressure is the bottom hole pressure calculated according to the bottom hole pressure formula of the fixed production stage under the first time length in the given productivity prediction time length, and the target bottom hole pressure is the bottom hole pressure at the end of the preset fixed pressure production stage; if the first bottom hole pressure is less than the target bottom hole pressure, the bottom hole pressure of the fixed production stage is equal to the first bottom hole pressure, the cumulative oil and gas reservoir production is equal to the multiple of the first time length of the initial oil and gas reservoir production, and the pressure of each area is obtained according to the pressure formula of each area in the fixed production stage; if the first bottom hole pressure is greater than or equal to the target The bottom hole pressure is equal to the target bottom hole pressure in the constant pressure production stage, the cumulative oil and gas reservoir production is obtained by integrating the oil and gas reservoir production in the constant pressure production stage with time, the oil and gas reservoir production in the constant pressure production stage is obtained according to the oil and gas reservoir production formula in the constant pressure production stage, and the pressure of each region is obtained according to the pressure formula of each region in the constant pressure production stage; according to the first bottom hole pressure and the pressure of each region in the constant production stage or the target bottom hole pressure and the pressure of each region in the constant pressure production stage, the parameters of the seepage mathematical model are updated, and it is determined whether the first time length is less than the production capacity prediction time length; if so, the oil and gas reservoir production and bottom hole pressure distribution of the complete production stage are output.

[0228] Figure 4 Schematic diagram of the iterative solution method provided by an embodiment of the present application. Figure 4As shown, the seepage mathematical model obtained in the above embodiment can be initialized first, and used to give shale reservoir and fluid physical parameters, such as density and reservoir temperature, according to the actual conditions of the target block (or target area); and give the production capacity prediction time step, including the production capacity prediction time t end , and production system conversion conditions, which include the initial gas production q sc and target bottom hole flowing pressure (or target bottom hole pressure) p wf .

[0229] At the tth time step, that is, when the production time is t, the bottom hole pressure formula of the fixed production stage can be used to calculate Calculate the pressure p at this time wf (t), that is, the first bottom hole pressure. Then, we can judge the p wf (t) and p wf Specifically, when p wf (t)<p wf When the production is in the fixed production stage, the daily gas production volume Q g =q sc , cumulative gas production c g =q sc t, bottom hole pressure is p wf (t), the pressures of the unfractured zone, the external fractured zone, the internal fractured zone, the unsupported fracture zone, and the supported fracture zone are p m (t), p om (t), p Im (t), p oF (t) and p IF (t) can be calculated by referring to the pressure formula of each area in the fixed production stage in the above embodiment.

[0230] When p wf (t)≥p wf When the pressure is constant, the production is in the constant pressure stage. At this time, according to the gas production formula of the constant pressure production stage Calculate daily gas production Q g , cumulative gas production c g =∫q sc ·dt, bottom hole pressure is p wf (t) = p wf The pressures of the unfractured zone, the external fractured zone, the internal fractured zone, the unsupported fracture zone, and the supported fracture zone are p respectively. m (t), p om (t), p Im (t), p oF (t) and p IF (t) can be calculated with reference to the above embodiment.

[0231] Furthermore, the bottom hole pressure p can be used to wf (t) and the pressure of each area at different production stages to update the parameters of the seepage mathematical model. end When p wf (t) and p wf On the contrary, the gas production and bottom hole pressure distribution in the complete production stage are obtained.

[0232] Figure 5 This is a comparison chart of the production capacity prediction results provided by an embodiment of the present application and the prediction results of commercial numerical simulation software. Figure 5 As shown, it is the production time (d)-daily gas production (10 4 m 3 / d) and production time (d)-bottom hole pressure (MPa), using numerical solution (Eclipse) and semi-analytical model, that is, using commercial numerical simulation software to predict gas production and using the method provided by this application to predict gas production. Figure 5 The comparison results show that the results predicted by the method provided in this application are consistent with the numerical simulation results, indicating that the method provided in this application can be used to predict the production capacity of shale oil and gas reservoirs.

[0233] Based on the above embodiment, the oil and gas reservoir productivity prediction method may further include: assuming linear flow of fluid in the shale reservoir to be predicted, thereby setting the flow characteristics of the fluid in each region when constructing the physical model. In practice, production data from many unconventional oil and gas wells demonstrates the presence of long straight-line segments on the double-logarithmic curve of production versus time, i.e., the presence of a linear flow phase. This linear flow phase can last for a very long time, potentially several years or even more than a decade. Therefore, the flow of fluid in the shale reservoir to be predicted can be assumed to be linear, i.e., the fluid in each region can flow linearly.

[0234] In combination with the above embodiments, the method provided in this application can obtain the following experimental results.

[0235] Figure 6 FIG. 1 is a schematic diagram showing the effect of fracture stress sensitivity on shale oil and gas reservoir production provided by an embodiment of the present application. Figure 6 As shown, Figure 6 The upper figure is the production time (d) - daily gas production (10 4 m 3 / d) and production time (d)-cumulative gas production (10 8 m 3 / d), the comparison results of gas production under the consideration of stress sensitivity and without considering stress sensitivity, where the solid line represents daily gas production and the dotted line represents cumulative gas production; the figure below is the production time (d)-bottom hole pressure (MPa), the comparison results of bottom hole pressure under the consideration of stress sensitivity and without considering stress sensitivity. Figure 6 The comparison results show that deep shale reservoirs have strong stress sensitivity. When the stress sensitivity effect is considered, the stable production period of the producing oil and gas reservoir becomes shorter, the bottom hole pressure decreases faster, and the cumulative gas production is low; when the stress sensitivity effect is not considered, the obtained gas production will be too high.

[0236] Figure 7 This is a schematic diagram of the impact of the initial oil and gas reservoir production on the shale oil and gas reservoir production during the fixed production phase provided by an embodiment of the present application. Figure 7 As shown, Figure 7 The upper figure is the production time (d) - daily gas production (10 4 m 3 / d) and production time (d)-cumulative gas production (10 8 m 3 / d), at different initial gas production (45000m 3 / d, 60000m 3 / d and 75000m 3 / d) gas production comparison results; the figure below is the production time (d) - bottom hole pressure (MPa), the bottom hole pressure comparison results at different initial gas production rates. Figure 7 From the comparison results, it can be seen that the higher the initial gas production, the shorter the stable production period of the producing oil and gas reservoir, and the faster the bottom hole pressure decreases. However, in the same time, the production in the stable production stage is higher, and the final production will also be higher.

[0237] Figure 8 This is a schematic diagram of the effect of bottom hole pressure on shale oil and gas reservoir production during the constant pressure production phase provided by an embodiment of the present application. Figure 8 As shown, Figure 8 The upper figure is the production time (d) - daily gas production (10 4 m 3 / d) and production time (d)-cumulative gas production (10 8 m 3 / d), the gas production comparison results at different bottom hole pressures (3MPa, 5MPa and 7MPa); the figure below is the production time (d) - bottom hole pressure (MPa), the bottom hole pressure comparison results at different bottom hole pressures. Figure 8 The comparison results show that when the production stage changes from fixed production to fixed pressure production, the higher the bottom hole pressure is, the shorter the stable production period of the oil and gas reservoir is, the faster the bottom hole pressure decreases, and the lower the cumulative gas production is.

[0238] Figure 9 This is a schematic diagram of the effect of the half-length of the propped fracture on shale gas production provided by an embodiment of the present application. Figure 9 As shown, Figure 9 The upper figure is the production time (d) - daily gas production (10 4 m 3 / d) and production time (d)-cumulative gas production (10 8 m 3 / d), the gas production rate comparison results at different prop fracture half lengths (10m, 30m and 50m); the figure below is the production time (d)-bottom hole pressure (MPa), the bottom hole pressure comparison results at different prop fracture half lengths. Figure 9 Comparison results show that, for a given total fracture half-length, increasing the propping fracture half-length increases the reservoir's stable production period, slows the rate of decline in bottomhole pressure, and significantly increases cumulative gas production. Therefore, increasing the propping fracture length significantly boosts reservoir production. In practice, increasing the propping fracture permeability or the matrix permeability within the fracturing zone is equivalent to increasing the propping fracture half-length.

[0239] Based on the above examples, it can be seen that in the development of deep shale oil and gas reservoirs, the production system and propped fractures have a significant impact on the oil and gas reservoir production of horizontal wells. Therefore, in the actual development of shale oil and gas reservoirs, the production method of pressure control and production limitation is usually adopted for oil and gas reservoir development.

[0240] In other embodiments, the oil and gas reservoir productivity prediction method provided in this application can also be applied to the productivity prediction of other unconventional oil and gas reservoirs developed using multi-stage fracturing horizontal well technology, such as coalbed methane reservoirs developed using multi-stage fracturing horizontal wells.

[0241] In summary, this application has at least the following advantages:

[0242] 1. The method comprehensively considers the seepage, diffusion, slippage, supercritical adsorption and desorption of oil and gas in deep shale, the stress sensitivity in supported and unsupported fractures, and the impact of changes in the working system during the production process on the productivity of shale oil and gas reservoirs. It is more in line with on-site fracturing and actual production conditions than a single production system, and provides more accurate theoretical guidance for accurately predicting the production of deep shale oil and gas reservoirs and evaluating the fracturing effect.

[0243] 2. The production capacity of deep shale oil and gas reservoirs is analyzed through dimensionless processing, perturbation transformation, Laplace transform and Steifest numerical inversion. Compared with semi-analytical and numerical solutions, the method provided in this application is simpler, faster in calculation, more convenient for field application, and more convenient for considering adding new flow mechanisms.

[0244] The following are device embodiments of the present application, which can be used to implement the method embodiments of the present application. For details not disclosed in the device embodiments of the present application, please refer to the method embodiments of the present application.

[0245] Figure 10 Schematic diagram of the structure of the oil and gas reservoir productivity prediction device provided by an embodiment of the present application. For the sake of convenience, only the parts related to the embodiment of the present application are shown. Figure 10 As shown, the oil and gas reservoir productivity prediction device 100 includes: an acquisition module 1001, a construction module 1002, a coupling module 1003, an analysis module 1004 and a determination module 1005. Among them:

[0246] An acquisition module 1001 is used to acquire the fracturing characteristics of the shale reservoir to be predicted;

[0247] A construction module 1002 is used to construct a physical model based on the fracturing characteristics. The physical model includes regions such as propped fracture areas, unpropped fracture areas, fractured inner areas, fractured outer areas, and unfractured areas. The different regions are divided based on the proppant filling status in the fractures of the shale reservoir to be predicted and the effect after fracturing.

[0248] The coupling module 1003 is used to couple the seepage control equations of each area in the fixed production stage and the fixed pressure production stage to obtain a seepage mathematical model. The fixed production stage is a stage where the production time is less than or equal to the critical production time, and the fixed pressure production stage is a stage where the production time is greater than the critical production time.

[0249] The analytical module 1004 is used to analytically solve the seepage mathematical model to obtain the bottom hole pressure distribution and oil and gas reservoir production in real space pseudo time corresponding to the shale reservoir to be predicted;

[0250] The determination module 1005 is used to determine the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in real space and real time based on the bottom hole pressure distribution and oil and gas reservoir production in real space and pseudo time.

[0251] In one possible implementation, the analytical module 1004 can be specifically used to analytically solve the seepage mathematical model through dimensionless processing, perturbation transformation, Laplace transform and Steifest numerical inversion to obtain the bottom hole pressure distribution and oil and gas reservoir production under real space pseudo-time corresponding to the shale reservoir to be predicted.

[0252] In one possible implementation, the coupling module 1003 can be specifically used to: determine the initial conditions, internal and external boundary conditions of each region and the flow-pressure coupling conditions between different regions based on the production system, actual boundary conditions and the flow-pressure relationship between different regions, wherein the initial conditions include the pressures of each point in different regions at the initial moment in the fixed-production stage and the fixed-pressure production stage; according to the initial conditions, internal and external boundary conditions of each region and the flow-pressure coupling conditions between different regions, couple the seepage control equations of each region in the fixed-production stage and the fixed-pressure production stage to obtain a seepage mathematical model.

[0253] In one possible implementation, the determination module 1005 can be specifically used to: determine the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in the complete production stage in real space and real time using an iterative solution method based on the bottom hole pressure distribution and oil and gas reservoir production in real space pseudo time.

[0254] In one possible implementation, the iterative solution method in the oil and gas reservoir productivity prediction device may include: judging whether the first bottom hole pressure is less than the target bottom hole pressure, the first bottom hole pressure is the bottom hole pressure calculated according to the bottom hole pressure formula of the fixed production stage under the first time length in the given productivity prediction time length, and the target bottom hole pressure is the bottom hole pressure at the end of the preset fixed pressure production stage; if the first bottom hole pressure is less than the target bottom hole pressure, the bottom hole pressure of the fixed production stage is equal to the first bottom hole pressure, the cumulative oil and gas reservoir production is equal to the multiple of the first time length of the initial oil and gas reservoir production, and the pressure of each area is obtained according to the pressure formula of each area in the fixed production stage; if the first bottom hole pressure is greater than or equal to At the target bottom hole pressure, the bottom hole pressure in the constant pressure production stage is equal to the target bottom hole pressure, the cumulative oil and gas reservoir production is obtained by integrating the oil and gas reservoir production in the constant pressure production stage with time, the oil and gas reservoir production in the constant pressure production stage is obtained according to the oil and gas reservoir production formula in the constant pressure production stage, and the pressure of each region is obtained according to the pressure formula of each region in the constant pressure production stage; according to the first bottom hole pressure and the pressure of each region in the constant production stage or the target bottom hole pressure and the pressure of each region in the constant pressure production stage, update the parameters of the seepage mathematical model, and judge whether the first time length is less than the production capacity prediction time length; if so, output the oil and gas reservoir production and bottom hole pressure distribution of the complete production stage.

[0255] In one possible implementation, the seepage control equation in the oil and gas reservoir productivity prediction device can be established in the following manner: based on the seepage, diffusion, slippage and supercritical adsorption and desorption of the shale reservoir to be predicted, the seepage control equations corresponding to the fractured inner zone, the fractured outer zone and the unfractured zone are established respectively; based on the pseudo-permeability modulus and stress sensitivity of the supported fracture zone and the unsupported fracture zone, the seepage control equations of the supported fracture zone and the unsupported fracture zone are established respectively.

[0256] In a possible implementation, the oil and gas reservoir productivity prediction device may further include: linear flow of fluid in the shale reservoir to be predicted, which is used to set the flow characteristics of the fluid in each area when the construction module constructs the physical model.

[0257] The oil and gas reservoir productivity prediction device provided in the embodiment of the present application has similar implementation principles and technical effects as those of the above embodiment. Please refer to the above embodiment for details and will not be repeated here. Figure 11 Schematic diagram of the structure of an electronic device provided by an embodiment of the present application. Figure 11 As shown, the electronic device 110 includes: at least one processor 1101, a memory 1102, a communication interface 1103, and a system bus 1104. The memory 1102 and the communication interface 1103 are connected to the processor 1101 via the system bus 1104 and communicate with each other. The memory 1102 is used to store instructions, the communication interface 1103 is used to communicate with other devices, and the processor 1101 is used to call instructions in the memory to execute the solution of the embodiment of the oil and gas reservoir productivity prediction method described above. The specific implementation methods and technical effects are similar and will not be repeated here.

[0258] Figure 11 The processor 1101 mentioned in the specification can be a general-purpose processor, including a central processing unit, a network processor (NP), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, and discrete hardware components.

[0259] The memory 1102 may include random access memory (RAM), and may also include static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk, for example, at least one magnetic disk storage.

[0260] The communication interface 1103 is used to implement communication between the oil and gas reservoir productivity prediction device and other devices (such as a client).

[0261] The system bus 1104 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The system bus 1104 may be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, the figure shows only one thick line, but this does not imply that there is only one bus or only one type of bus.

[0262] Those skilled in the art will understand that Figure 11 The electronic device shown does not constitute a limitation of the electronic device, and may include more or fewer components than shown, or combine certain components, or arrange components differently.

[0263] An embodiment of the present application further provides a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed, the above-mentioned oil and gas reservoir productivity prediction method is implemented.

[0264] An embodiment of the present application also provides a computer program product, including a computer program, which implements the above oil and gas reservoir productivity prediction method when executed.

[0265] An embodiment of the present application also provides a chip for executing instructions, and the chip is used to execute the oil and gas reservoir productivity prediction method as described in any of the above method embodiments.

[0266] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with the relevant laws, regulations and standards of relevant countries and regions, and provide corresponding operation entrances for users to choose to authorize or refuse.

[0267] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of the present application and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0268] It should be understood that the present application is not limited to the exact structure described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for predicting oil and gas reservoir productivity, characterized in that: include: Obtaining the fracturing characteristics of the shale reservoir to be predicted; Based on the fracturing characteristics, a physical model is constructed, wherein the physical model includes regions including a propped fracture region, an unpropped fracture region, an inner fracture stimulation region, an outer fracture stimulation region, and an unfracture stimulation region, wherein the different regions are divided according to the proppant filling conditions in the fractures of the shale reservoir to be predicted and the effects after fracturing; The seepage control equations of each region in the fixed-production stage and the fixed-pressure production stage are coupled to obtain a seepage mathematical model. The fixed-production stage is a stage where the production time is less than or equal to the critical production time, and the fixed-pressure production stage is a stage where the production time is greater than the critical production time. Analytically solving the seepage mathematical model to obtain the bottom hole pressure distribution and oil and gas reservoir production corresponding to the shale reservoir to be predicted in real space pseudo-time; The oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in real space and real time are determined according to the bottom hole pressure distribution and oil and gas reservoir production in the real space pseudo time.

2. The oil and gas reservoir productivity prediction method according to claim 1, characterized in that: The analytical solution of the seepage mathematical model to obtain the bottom hole pressure distribution and oil and gas reservoir production corresponding to the shale reservoir to be predicted in real space pseudo-time includes: The mathematical model of seepage is analytically solved through dimensionless processing, perturbation transformation, Laplace transformation and Steifest numerical inversion to obtain the bottom hole pressure distribution and oil and gas reservoir production under real space pseudo-time corresponding to the shale reservoir to be predicted.

3. The oil and gas reservoir productivity prediction method according to claim 1 or 2, characterized in that: The seepage control equations of each region in the fixed production stage and the fixed pressure production stage are coupled to obtain a seepage mathematical model, including: Determine the initial conditions, internal and external boundary conditions, and flow-pressure coupling conditions for each region based on the production system, actual boundary conditions, and the flow-pressure relationship between different regions. The initial conditions include the pressure at each point in the different regions at the initial moment during the fixed-rate production phase and the fixed-pressure production phase. According to the initial conditions of each area, the internal and external boundary conditions and the flow-pressure coupling conditions between different areas, the seepage control equations of each area in the fixed production stage and the fixed pressure production stage are coupled to obtain a seepage mathematical model.

4. The oil and gas reservoir productivity prediction method according to claim 1 or 2, characterized in that: The determining of the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in real space and real time based on the bottom hole pressure distribution and oil and gas reservoir production in real space and real time includes: According to the bottom hole pressure distribution and oil and gas reservoir production in the real space pseudo time, an iterative solution method is adopted to determine the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in the complete production stage in real space and real time.

5. The oil and gas reservoir productivity prediction method according to claim 4, characterized in that: The iterative solution method comprises: determining whether a first bottom hole pressure is less than a target bottom hole pressure, where the first bottom hole pressure is the bottom hole pressure calculated according to a bottom hole pressure formula for a fixed production phase for a first duration in a given production capacity forecast duration, and the target bottom hole pressure is the bottom hole pressure at the end of a preset fixed pressure production phase; If the first bottom hole pressure is less than the target bottom hole pressure, the bottom hole pressure during the fixed production phase is equal to the first bottom hole pressure, the cumulative oil and gas reservoir production is equal to a multiple of the first duration of the initial oil and gas reservoir production, and the pressure of each region is obtained according to the pressure formula for each region during the fixed production phase; If the first bottom hole pressure is greater than or equal to the target bottom hole pressure, the bottom hole pressure in the constant pressure production stage is equal to the target bottom hole pressure, the cumulative oil and gas reservoir production is obtained by integrating the oil and gas reservoir production in the constant pressure production stage with time, the oil and gas reservoir production in the constant pressure production stage is obtained according to the oil and gas reservoir production formula in the constant pressure production stage, and the pressure of each region is obtained according to the pressure formula of each region in the constant pressure production stage; updating the parameters of the seepage mathematical model according to the first bottom hole pressure and the pressure of each region in the fixed production phase or the target bottom hole pressure and the pressure of each region in the fixed pressure production phase, and determining whether the first duration is less than the production capacity prediction duration; If so, the reservoir production and bottom hole pressure distribution during the complete production phase are output.

6. The oil and gas reservoir productivity prediction method according to claim 1 or 2, characterized in that: The seepage control equation is established in the following way: According to the seepage, diffusion, slippage and supercritical adsorption and desorption of the shale reservoir to be predicted, the seepage control equations corresponding to the inner fractured zone, the outer fractured zone and the unfractured zone are respectively established; According to the pseudo-permeability modulus and stress sensitivity of the propped fracture zone and the unpropped fracture zone, the seepage control equations of the propped fracture zone and the unpropped fracture zone are established respectively.

7. The oil and gas reservoir productivity prediction method according to claim 1 or 2, characterized in that: Also includes: The fluid in the shale reservoir to be predicted flows linearly, which is used to set the flow characteristics of the fluid in each area when constructing the physical model.

8. An oil and gas reservoir productivity prediction device, characterized in that: include: An acquisition module, used for acquiring the fracturing characteristics of the shale reservoir to be predicted; A construction module is used to construct a physical model based on the fracturing characteristics, wherein the physical model includes regions including a propped fracture area, an unpropped fracture area, an inner fractured area, an outer fractured area, and an unfractured area, wherein the different regions are divided according to the proppant filling conditions in the fractures of the shale reservoir to be predicted and the effect after fracturing; A coupling module is used to couple the seepage control equations of each area in the fixed-production stage and the fixed-pressure production stage to obtain a seepage mathematical model. The fixed-production stage is a stage where the production time is less than or equal to the critical production time, and the fixed-pressure production stage is a stage where the production time is greater than the critical production time. An analytical module, configured to analytically solve the seepage mathematical model to obtain the bottom hole pressure distribution and oil and gas reservoir production under real space pseudo-time corresponding to the shale reservoir to be predicted; The determination module is used to determine the oil and gas reservoir production and bottom hole pressure distribution of the shale reservoir to be predicted in real space and real time according to the bottom hole pressure distribution and oil and gas reservoir production in the real space pseudo time.

9. An electronic device, characterized in that: include: memory and processor; The memory is used to store program instructions; The processor is configured to call program instructions in the memory to execute the oil and gas reservoir productivity prediction method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer-executable instructions, and when the computer-executable instructions are executed, the oil and gas reservoir productivity prediction method according to any one of claims 1 to 7 is implemented.

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