Construction method of shale fracture long-term flow conductivity calculation model

Abstract

The invention belongs to the field of petroleum and natural gas development, and particularly discloses a method for constructing a shale fracture long-term flow conductivity calculation model, which comprises the following steps of: establishing a shale damage evolution equation under stress-temperature-time coupling; the method comprises the following steps of: acquiring a constitutive relation of an Abel damper under a constant stress by applying a Riemann-Liouville fractional calculus operator, then replacing a Newton damper in a Nishihara model with the Abel damper, and establishing a shale damage creep constitutive model under stress-temperature-time coupling by utilizing a Boltzmann superposition principle and a Laplace transformation property; calculating crack width and crack permeability; and a shale fracture long-term flow conductivity calculation model based on the fractional order damage creep effect is established in combination with the fracture width and permeability expression. The method can improve the calculation precision and accuracy of the long-term flow conductivity of the crack.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of oil and gas development, more particularly, to a method for constructing a long-term fracture conductivity calculation model of shale. BACKGROUND

[0002] After a series of complex deposition and diagenesis, the physical properties of shale reservoirs, such as porosity and permeability, are generally poor. Hydraulic fracturing technology is the most common technical means for improving shale reservoirs to obtain commercial industrial gas flow. Field production data of shale gas reservoirs show that the natural gas production has a significant downward trend in the first 5-6 months after the reservoir is improved. This is mainly because the shale reservoirs exhibit significant creep characteristics under the action of overburden pressure, and the embedding of proppant particles into the formation is very serious, which makes it difficult for the hydraulic fracture to maintain a stable open state for a long time, thereby reducing the fracture conductivity and narrowing the gas seepage channel. Therefore, accurately predicting the fracture conductivity is of great significance to improve the efficiency of shale gas production.

[0003] Currently, the methods for studying fracture conductivity can be divided into two categories: experimental testing and theoretical modeling. Experimental testing can directly observe the change rule of conductivity under different conditions, but it often requires a large amount of manpower, material resources and time cost. In contrast, the theoretical modeling method has the advantages of high calculation accuracy and low cost, and is increasingly valued by scholars in studying fracture conductivity. The existing technology calculates the elastic embedding depth of proppant, the deformation of proppant and the change of fracture width based on the Hertz contact theory, and obtains the relationship between fracture width change and time. After Laplace transformation and inverse Laplace transformation, a long-term fracture conductivity prediction model considering the creep effect of rock is established (Ren L, Hu ZY, Zhao JZ, Lin R, Wu JF, Song Y, Lin C. (2023). Impact of Creep Effect on Hydraulic Fracture Long-Term Conductivity in Deep Shale Reservoirs[J]. J Energ Resour 145(7): 073301.). It is worth noting that the technology uses the classic Maxwell model to calculate the creep embedding amount of proppant. However, the Maxwell model is a series connection of a Hooke body and a Newton damper, which can only describe the decay creep and stable creep stages in the viscoelastic-plastic deformation of rock, and is not ideal for capturing the mechanical behavior of accelerated creep. Deep shale is often in a complex geological environment of high temperature and high pressure, and its mechanical properties will inevitably be damaged and deteriorated. If the classic Maxwell model is still used to describe the creep behavior, the predicted fracture width change will have a large error, and ultimately affect the calculation accuracy and accuracy of long-term fracture conductivity.

[0004] Therefore, how to improve the calculation accuracy and accuracy of long-term fracture conductivity is a difficult problem in current research. SUMMARY

[0005] In view of the defects of the prior art, the purpose of the present application is to provide a method for constructing a shale fracture long-term conductivity calculation model, which can improve the calculation accuracy and accuracy of long-term fracture conductivity.

[0006] To achieve the above-mentioned purpose, in a first aspect, the present application provides a method for constructing a shale fracture long-term conductivity calculation model, comprising the following steps: S10, according to the rock mechanics and statistical damage theory, a shale damage evolution equation under stress-temperature-time coupling is established; S20, a Riemann-Liouville fractional calculus operator is applied to obtain the constitutive relationship of the Abel damper under constant stress, then the Newton damper in the classical Nishihara model is replaced by the Abel damper, and a shale damage creep constitutive model under stress-temperature-time coupling is established by using the Boltzmann superposition principle and the Laplace transform property; S30, according to the fractional order damage creep model, the embedding depth of the proppant on the rock surface and the deformation amount of the proppant are obtained, and the fracture width under the action of the closure pressure is calculated by comprehensively considering the effects of the proppant deformation, embedding and rock creep; S40, according to the geometric relationship of the proppant arrangement distribution, the fracture porosity, pore throat radius and tortuosity relationship at any moment are obtained, and the fracture permeability is calculated by applying the porous medium Kozeny-Carman equation; S50, the fracture long-term conductivity calculation model based on the fractional order damage creep effect is established by combining the fracture width expression in step S30 and the permeability expression in step S40.

[0007] The application has the beneficial effects that the application comprehensively considers the deterioration effects of stress, temperature and time on the mechanical properties of rock, and establishes a total damage evolution equation. On this basis, the application fully utilizes the advantages of the fractional order integral and differential in reflecting the nonlinearity and memory dependence of system development, improves the classical Nishihara model, and proposes a fractional order damage creep model. The model can accurately describe the deformation characteristics of each creep stage of rock, thereby laying a solid foundation for the construction of the subsequent fracture long-term conductivity model.

[0008] As a further preferred, in step S10, the shale damage evolution equation under stress-temperature-time coupling is:

[0009] In the formula, D STt is a stress-temperature-time coupling damage variable; E T is the elastic modulus of rock at temperature T is the elastic modulus of rock at room temperature; E 0 is the elastic modulus of rock at room temperature; m and F 0 are Weibull distribution parameters; F is the strength of rock microelement; ω is a time-dependent damage correction coefficient; t is the creep time.

[0010] As a further preferred, in step S20, the constitutive relation of the Abel damper under constant stress is:

[0011] wherein, ε t ) is strain; σ η 1 γ is the viscous coefficient of the Abel damper in the viscoelastic component; γ is the fractional order; t is the creep time; Γ (·) is the Gamma function.

[0012] As a further preferred, in step S20, the shale damage creep constitutive model under stress-temperature-time coupling is:

[0013] wherein, D STt is the stress-temperature-time coupling damage variable; E T is the elastic modulus of the rock at temperature T ; E 0 is the elastic modulus of the rock at room temperature; ε t ) is strain; σ σ y is the long-term strength of the shale; η 1 γ is the viscous coefficient of the Abel damper in the viscoelastic component; γ is the fractional order; t is the creep time; Γ (·) is the Gamma function; α T is the thermal expansion coefficient; Δ T is the temperature change; η 2 γ is the viscous coefficient of the Abel damper in the visco-plastic component.

[0014] As a further preferred, in step S30, the calculation formula of the embedding depth of the proppant on the rock surface and the deformation amount of the proppant is:

[0015]

[0016] wherein, h is the embedding depth of the proppant on the rock surface; p ​​​​c Pc is the closure pressure; E * Ee is the equivalent elastic modulus; R R is the proppant radius; E E0 is the elastic modulus of the rock at room temperature; D STt D is the stress-temperature-time coupling damage variable; α T a is the thermal expansion coefficient; E T E is the elastic modulus of the rock at temperature T ; η 1 γ is the viscous coefficient of the Abel damper in the viscoelastic component; γ is the fractional order; Γ (·) is the Gamma function; Δ T is the temperature change; d rock is the thickness of the rock directly in contact with the proppant; Δ d prop is the proppant deformation; d prop is the height of the proppant along the direction of the fracture width; E prop is the elastic modulus of the proppant; δ is the contact depth.

[0017] As a further preferred, in step S30, the calculation formula of the fracture width considering the proppant deformation, embedding and rock creep effect is:

[0018] In the formula, w f is the fracture width; w f0 is the initial fracture width; p c Pc is the closure pressure; E * Ee is the equivalent elastic modulus; R R is the proppant radius; d rock is the thickness of the rock directly in contact with the proppant; ε ( t ) is the strain; δ is the contact depth; d prop is the height of the proppant along the direction of the fracture width; E prop is the elastic modulus of the proppant.

[0019] As a further preferred, in step S40, the relationship of fracture porosity, pore throat radius and tortuosity at any time is respectively:

[0020]

[0021]

[0022] In the formula, is the porosity; is the initial porosity; w f0 is the initial fracture width; Δd prop is the proppant deformation amount; r is the pore throat radius; r 0 is the initial pore throat radius; τ is the tortuosity; τ 0 is the initial tortuosity.

[0023] As a further preferred, in step S40, the fracture permeability calculation formula is:

[0024] In the formula, k f is the fracture permeability; is the porosity; r is the pore throat radius; τ is the tortuosity.

[0025] As a further preferred, in step S50, the shale fracture long-term conductivity calculation model based on fractional order damage creep effect is:

[0026] In the formula, F RCD is the fracture conductivity; k f is the fracture permeability; w f is the fracture width.

[0027] In a second aspect, the present application provides a shale fracture long-term conductivity calculation model construction device, comprising a processor and a storage medium, the processor loads and executes the instructions and data in the storage medium to realize the shale fracture long-term conductivity calculation model construction method as described above.

[0028] It can be understood that the beneficial effects of the above-mentioned second aspect can be referred to the related description in the above-mentioned first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a flowchart of a construction method of a shale fracture long-term conductivity calculation model provided by an embodiment of the present application; Figure 2 is a fractional order damage creep model mode diagram provided by an embodiment of the present application; Figure 3 is a proppant distribution mode diagram in a fracture provided by an embodiment of the present application; Figure 4 is a proppant and shale interaction mechanism schematic diagram provided by a specific embodiment of the present application; Figure 5 is a comparison diagram of model data and conductivity test results of the present embodiment provided by a specific embodiment of the present application; Figure 6 is a relationship diagram of the influence of proppant elastic modulus on conductivity provided by a specific embodiment of the present application; Figure 7 is a relationship diagram of the influence of proppant particle size on conductivity provided by a specific embodiment of the present application; Figure 8 is a relationship diagram of the influence of closure pressure on conductivity provided by a specific embodiment of the present application. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings of the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0031] In the shale gas production process, due to the creep characteristics of the reservoir itself, the embedding of proppants into the formation is extremely serious, which causes the fracture conductivity to gradually decrease over time, and brings severe challenges to the safe and efficient production of shale gas. Therefore, in the present application, the deterioration of stress, temperature and time on the mechanical properties of shale is fully considered, and a construction method of a shale fracture long-term conductivity calculation model based on fractional order damage creep effect is established, as shown in Figure 1 The construction method includes steps S10-S50, which are described in detail as follows: Step S10, according to rock mechanics and statistical damage theory, a shale damage evolution equation under stress-temperature-time coupling is established.

[0032] In the embodiment, the shale damage evolution equation under stress-temperature-time coupling in step S10 is: (1) In the formula, D STt is a stress-temperature-time coupling damage variable, dimensionless; E T is the elastic modulus of the rock at temperature T , MPa; E 0 is the elastic modulus of the rock at room temperature, MPa; m and F 0 are Weibull distribution parameters, dimensionless; F is the strength of a rock microelement, dimensionless; ω is a time-dependent damage correction coefficient, h -1 ; t is a creep time, h.

[0033] In step S20, the constitutive relationship of the Abel damper under constant stress is obtained by applying the Riemann-Liouville fractional calculus operator, and then the Newton damper in the classical Nishihara model is replaced by the Abel damper, and by using the Boltzmann superposition principle and the Laplace transform property, a shale damage creep constitutive model under stress-temperature-time coupling is established.

[0034] In the embodiment, in step S20, the constitutive relationship of the Abel damper under constant stress is: (2) In the formula, ε ( t ) is a strain, dimensionless; σ is a stress, MPa; η 1 γ is a viscous coefficient of the Abel damper in the viscoelastic component, MPa·h γ ; γ is a fractional order, dimensionless; Γ (·) is a Gamma function, .

[0035] In step S20, the classic Nishihara model, composed of Hooke bodies, viscoelastic bodies, and viscoplastic bodies connected in series, can describe the decay and steady-state stages of creep relatively well, but its performance in depicting accelerated creep is not particularly ideal. This application improves the classic Nishihara model by considering the damage and degradation effects of each basic mechanical component and replacing the Newton damper with an Abel damper, aiming to more accurately simulate the entire process of rock creep deformation. Figure 2 Using the Boltzmann superposition principle and the Laplace transform property, a constitutive model of shale damage creep under stress-temperature-time coupling is established: (3) In the formula: α T The coefficient of thermal expansion is °C. -1 ;Δ T The change in temperature is expressed in °C. σ y The long-term strength of shale is expressed in MPa. η 2 γ Here is the viscosity coefficient of the Abel damper in the viscoplastic component, in MPa·h γ .

[0036] Step S30: Based on the fractional-order damage creep model established in step S20, obtain the proppant embedment depth and proppant deformation on the rock surface, and calculate the crack width under the action of closure pressure, taking into account the effects of proppant deformation, embedment and rock creep.

[0037] In this embodiment, during the hydraulic fracturing process, proppant particles are laid in multiple layers and arranged uniformly in a rhomboid shape within the hydraulic fracture, such as... Figure 3 As shown. Based on the fractional-order damage creep model established in step S20, the formulas for calculating the proppant embedment depth and proppant deformation on the rock surface are: (4) (5) In the formula: p c The closing pressure is in MPa. E * The equivalent elastic modulus is expressed in MPa. R The radius of the proppant is in mm; d rock Thickness of rock in direct contact with proppant, in mm; Δ d prop The deformation of the proppant is expressed in mm. d propThe height of the proppant along the crack width direction, in mm; E prop The elastic modulus of the proppant is expressed in MPa. δ The contact depth is in mm.

[0038] Step S30: As Figure 4 As shown, the crack width is controlled by the proppant embedment depth and deformation. Combining equations (4) and (5), we obtain the expression for the crack width at any given time, taking into account the effects of proppant deformation, embedment, and rock creep: (6) In the formula: w f The crack width is in mm; w f0 The initial crack width is in mm.

[0039] Step S40: Based on the geometric relationship of the proppant arrangement, obtain the relationships between fracture porosity, pore throat radius, and tortuosity at any given time. Calculate fracture permeability using the Kozeny-Carman equation for porous media.

[0040] In this embodiment, in step S40, the relationships between crack porosity, pore throat radius, and tortuosity at any given time are as follows: (7) (8) (9) In the formula: Porosity is a dimensionless quantity. Initial porosity, dimensionless; r Where is the throat radius, in μm; r 0 represents the initial throat radius, in μm; τ The degree of tortuosity is dimensionless; τ 0 represents the initial tortuosity, which is dimensionless.

[0041] In step S40, the permeability of the porous medium can be determined by the Kozeny-Carman equation, which is a function of porosity, pore throat radius, and tortuosity. The formula for calculating fracture permeability is: (10) In the formula: k f For crack permeability, 10 -3 μm 2 .

[0042] Step S50, combined with the crack width expression in step S30 and the permeability expression in step S40, a shale fracture long-term conductivity calculation model based on fractional order damage creep effect is established.

[0043] In this embodiment, the fracture conductivity is a key parameter for evaluating the fracturing effect and the degree of difficulty of oil and gas migration, which is defined as the product of permeability and fracture width. Combined with formula (6) and formula (10), the shale fracture long-term conductivity calculation model expression based on fractional order damage creep effect is obtained: (11) In the formula: F RCD Fracture conductivity, 10 -3 μm 2 ·cm.

[0044] It should be noted that the traditional fracture conductivity technology also considers the creep effect to establish a shale long-term conductivity prediction model. However, it does not improve the creep model, but directly embeds the classic Maxwell creep model into the expression for calculating the fracture width. When predicting the long-term fracture conductivity, the most core step is to establish the corresponding creep model. Some common creep models include Maxwell model, Kelvin model, Burgers model and Nishihara model. The biggest difference between the present application and the traditional technology is that the present application improves the Nishihara model. The specific improvement method is to obtain a damage creep constitutive model considering the effects of stress, temperature and time based on fractional calculus and damage mechanics theory. The accuracy of the damage creep constitutive model is effectively verified by laboratory experimental data, and the fitting accuracy is higher than that of the classic Maxwell model, Kelvin model, Burgers model and Nishihara model. After verifying the rationality of the damage creep constitutive model, it is applied to the subsequent fracture conductivity modeling.

[0045] The beneficial effects of the present application are: the present application comprehensively considers the deterioration of stress, temperature and time on the mechanical properties of rock, and establishes a total damage evolution equation. On this basis, the present application fully utilizes the advantages of fractional order integral in reflecting the nonlinearity and memory dependence of system development, improves the classic Nishihara model, and proposes a fractional order damage creep model. The model can accurately describe the deformation characteristics of each creep stage of rock, thereby laying a solid foundation for the construction of subsequent fracture long-term conductivity model.

[0046] The construction method of the shale fracture long-term conductivity calculation model provided by the present application will be described in detail according to specific embodiments.

[0047] According to the data measured in the study of the influence of proppant packing on the flow conductivity of Eagle Ford shale by Mittal A, Rai CS, Sondergeld CH. (2018). Proppant-Conductivity Testing Under Simulated Reservoir Conditions: Impact of Crushing, Embedment, and Diagenesis on Long-Term Production in Shales[J]. SPE J 23(4): 1304-1315, the long-term fracture conductivity is calculated using the method of the present embodiment, and the calculation results of the present embodiment are compared with the experimental results to verify the rationality and accuracy of the present embodiment. In addition, the method of the present embodiment is compared with the Ren model (Ren L, Hu ZY, Zhao JZ, Lin R, Wu JF, Song Y, Lin C. (2023). Impact of Creep Effect on Hydraulic Fracture Long-Term Conductivity in Deep Shale Reservoirs[J]. J Energ Resour 145(7).), Zhang model (Zhang JC. (2014). Theoretical conductivity analysis of surface modification agent treated proppant[J]. Fuel 134 166-170.) to further demonstrate the reliability of the method of the present application. The basic parameters in the experimental data are shown in Table 1.

[0048] Table 1 Basic parameters of long-term fracture conductivity test

[0049] Figure 5 The matching results of the long-term conductivity test data for the method of the present embodiment, the Ren model, and the Zhang model are shown in Table 2. Figure 5 It can be seen that the fracture conductivity shows a clear nonlinear reduction trend over time, which has a good corresponding relationship with the creep behavior of the rock. Compared with the Ren model and the Zhang model, the matching accuracy of the test data of the method of the present embodiment shows a more satisfactory effect, and the determination coefficient R2 is 0.9999, which is much higher than that of the Ren model and the Zhang model. R 20.9897. This fully shows that the method of the embodiment can better predict the time evolution law of the long-term fracture conductivity.

[0050] Using the basic parameters in Table 1, further draw the relationship curve between the long-term fracture conductivity and the elastic modulus of the proppant ( Figure 6 ), the relationship curve between the long-term fracture conductivity and the proppant particle size ( Figure 7 ), and the relationship curve between the long-term fracture conductivity and the closure pressure ( Figure 8 ).

[0051] It can be seen from Figure 6 that as the elastic modulus of the proppant increases, the initial conductivity increases, the time required for the conductivity to decrease to 0 is prolonged, and the conductivity evolution curve as a whole moves upward along the coordinate system angle bisector. In fact, when the closure pressure is constant, the greater the elastic modulus of the proppant, the more difficult it is for the fracture to close, thereby effectively slowing down the influence of rock creep on the fracture conductivity.

[0052] It can be seen from Figure 7 that the proppant particle size mainly affects the initial conductivity and has no significant effect on the time during which the conductivity decreases to 0. During the increase of the proppant particle size from 50 / 80 mesh to 20 / 40 mesh, the conductivity curve becomes steeper.

[0053] It can be seen from Figure 8 that as the closure pressure increases, the conductivity-time curve becomes steeper and translates in the direction of decreasing conductivity. After 8.5 days of stress loading, the fracture conductivity decreases from 23.69 μm 2 ·cm when the closure pressure is 30 MPa to 7.88 μm 2 ·cm when the closure pressure is 40 MPa. As the closure pressure further increases to 50 MPa, the fracture conductivity has almost approached to 0. In addition, when the closure pressure is small, the fracture conductivity can be stably at a high level for a long time.

[0054] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for constructing a shale fracture long-term conductivity calculation model, characterized in that, The method comprises the following steps: S10, establishing a shale damage evolution equation under stress-temperature-time coupling according to rock mechanics and statistical damage theory; S20, obtaining a constitutive relationship of the Abel damper under constant stress by applying a Riemann-Liouville fractional calculus operator, then replacing the Newton damper in a classical Nishihara model with the Abel damper, and establishing a shale damage creep constitutive model under stress-temperature-time coupling by using Boltzmann superposition principle and Laplace transform properties; S30, obtaining a proppant embedding depth on a rock surface and a proppant deformation amount according to the fractional order damage creep model, and calculating a fracture width under closure pressure by comprehensively considering influences of proppant deformation, embedding and rock creep effects; S40, obtaining a relationship formula of fracture porosity, pore throat radius and tortuosity at any time according to a geometric relationship of proppant arrangement and distribution, and calculating a fracture permeability by applying a porous medium Kozeny-Carman equation; S50, combining the fracture width expression in step S30 and the permeability expression in step S40, and establishing a shale fracture long-term conductivity calculation model based on fractional order damage creep effects.

2. The method for constructing a shale fracture long-term conductivity calculation model according to claim 1, characterized in that, In step S10, the shale damage evolution equation under stress-temperature-time coupling is: wherein D STt is the stress-temperature-time coupling damage variable; E T is the elastic modulus of the rock at temperature T ; E 0is the elastic modulus of the rock at room temperature; m and F 0are Weibull distribution parameters; F is the strength of the rock element; ω is the time-dependent damage correction factor; t is the creep time.

3. The method for constructing a shale fracture long-term conductivity calculation model according to claim 1, characterized in that, In step S20, the constitutive relationship of the Abel damper under constant stress is: wherein ε (·) is the strain; t ) is the stress; σ (·) is the stress; η 1 γ (·) is the viscous coefficient of the Abel damper in the viscoelastic component; γ (·) is the fractional order; t (·) is the creep time; Γ (·) is the Gamma function.

4. The method for constructing a shale fracture long-term conductivity calculation model according to claim 1, characterized in that, In step S20, the shale damage creep constitutive model under stress-temperature-time coupling is: wherein D STt is the stress-temperature-time coupling damage variable; E T is the elastic modulus of the rock at temperature T ; E 0 is the elastic modulus of the rock at room temperature; ε ( t ) is the strain; σ is the stress; σ y is the long-term strength of the shale; η 1 γ is the Abel damper viscous coefficient in the viscoelastic component; γ is the fractional order; t is the creep time; Γ (·) is the Gamma function; α T is the thermal expansion coefficient; Δ T is the temperature variation; η 2 γ is the Abel damper viscous coefficient in the viscoplastic component.

5. The method for constructing a shale fracture long-term conductivity calculation model according to claim 1, characterized in that, In step S30, the calculation formula of the proppant embedding depth on the rock surface and the proppant deformation amount is: wherein, h is the embedment depth of the proppant into the rock surface; p c is the closure pressure; E * is the equivalent elastic modulus; R is the proppant radius; E 0 is the elastic modulus of the rock at room temperature; D STt is the stress-temperature-time coupled damage variable; α T is the thermal expansion coefficient; E T is the elastic modulus of the rock at temperature T ; η 1 γ is the viscous coefficient of the Abel damper in the viscoelastic component; γ is the fractional order; Γ (·) is the Gamma function; Δ T is the temperature change; d rock is the thickness of the rock in direct contact with the proppant; Δ d prop is the deformation of the proppant; d prop is the height of the proppant along the width of the fracture; E prop is the elastic modulus of the proppant; δ is the contact depth.

6. The method for constructing a shale fracture long-term conductivity calculation model according to claim 1, characterized in that, In step S30, the calculation formula of the fracture width by comprehensively considering influences of proppant deformation, embedding and rock creep effects is: wherein w f is the initial fracture width; w f0 is the initial fracture width; p c is the closure pressure; E * is the equivalent elastic modulus; R is the proppant radius; d rock is the thickness of the rock in direct contact with the proppant; ε t is the strain; δ is the contact depth; d prop is the height of the proppant along the fracture width direction; E prop is the proppant elastic modulus.​ 7. The method for constructing a shale fracture long-term conductivity calculation model according to claim 1, characterized in that, In step S40, the relationship formula of the fracture porosity, the pore throat radius and the tortuosity at any time is: wherein is the porosity; is the initial porosity; w f0 is the initial fracture width; Δd prop is the proppant deformation; r is the pore throat radius; r 0 is the initial pore throat radius; τ is the tortuosity; τ 0 is the initial tortuosity.

8. The method of claim 1, wherein, In step S40, the fracture permeability calculation formula is: wherein k f is the fracture permeability; is the porosity; r is the pore throat radius; τ is the tortuosity.

9. The method of constructing a model for calculating long-term fracture conductivity in shale of claim 1, wherein, In step S50, the shale fracture long-term conductivity calculation model based on fractional order damage creep effects is: wherein F RCD is the fracture conductivity; k f is the fracture permeability; w f is the fracture width.

10. A device for constructing a model for calculating long-term fracture conductivity in shale, characterized in that, The method comprises a processor and a storage medium, the processor loads and executes instructions and data in the storage medium to realize the shale fracture long-term conductivity calculation model construction method according to any one of claims 1-9. The method comprises a processor and a storage medium, the processor loads and executes instructions and data in the storage medium to realize the shale fracture long-term conductivity calculation model construction method according to any one of claims 1-9.

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