Well test analysis method, device and medium for tight gas reservoirs with weak recharge boundaries

Abstract

The present invention relates to a well test analysis method, device and medium for a tight gas reservoir with a weak recharge boundary. The method includes the following steps: establishing a well test physical model for a tight gas reservoir with a weak recharge boundary; establishing a dimensionless seepage mathematical model for a radial composite reservoir with a weak recharge boundary based on the seepage mathematical model of a finite conductivity fractured well; establishing a dimensionless seepage mathematical model for the fluid in the fracture; establishing a seepage mathematical model for a tight gas reservoir with a weak recharge boundary based on the dimensionless seepage mathematical model for a radial composite reservoir with a weak recharge boundary and the dimensionless seepage mathematical model for the fluid in the fracture; solving the seepage mathematical model for a tight gas reservoir with a weak recharge boundary to obtain the bottom hole pressure solution of the gas well under this model, and calculating its derivative, depicting the pressure and its derivative curves in a double logarithmic coordinate system to obtain the well test curve; based on the well test curve, conducting a sensitivity factor analysis of the well test model for a tight gas reservoir with a weak recharge boundary.

Description

Technical Field

[0001] The present invention relates to a method, device and medium for well test analysis of a tight gas reservoir with a weak recharge boundary, and belongs to the technical field of oil exploration and development. Background Art

[0002] Regarding the research on the seepage model of fractured vertical wells in tight gas reservoirs, the weak recharge boundary effect is rarely considered. The problem of weak recharge boundary was first proposed by the hydrogeology discipline and later introduced by predecessors for the theoretical analysis of gas reservoir seepage. It is mainly used to establish various recharge boundary characterization methods to study problems such as edge water supply, fault diversion, and dynamic reserve prediction, but no research method for characterizing the recharge boundary of tight gas reservoirs has been formed.

[0003] Well test analysis is a key technology in the development of unconventional gas fields. Field practices in some tight gas fields show that there is an external weak recharge phenomenon in the fracturing reconstruction area after gas well fracturing, and traditional well test analysis models are no longer applicable. To develop tight gas reservoirs more efficiently, it is particularly necessary to establish an applicable well test analysis method for tight gas reservoirs with weak recharge boundaries. Summary of the Invention

[0004] In view of the above technical problems, the present invention provides a method, device and medium for well test analysis of a tight gas reservoir with a weak recharge boundary. This method can effectively perform dynamic inversion on a tight gas reservoir with a weak recharge boundary to obtain more real and reliable dynamic parameters and reveal the seepage law of reservoir fluids in a tight gas reservoir with a weak recharge boundary.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for well test analysis of a tight gas reservoir with a weak recharge boundary, the method is based on establishing a well test model for a tight gas reservoir with a weak recharge boundary. The well test model for a tight gas reservoir includes a physical model for well test of a tight gas reservoir and a mathematical model for seepage of a tight gas reservoir, and includes the following steps:

[0007] Based on the interface recharge factor and the external fluid recharge area, establish a physical model for well test of a tight gas reservoir with a weak recharge boundary;

[0008] Based on the physical model for well test of a tight gas reservoir and the mathematical model for seepage of a finite conductivity fractured well, establish a dimensionless mathematical model for radial composite reservoir seepage with a weak recharge boundary;

[0009] Based on the physical model for well test of a tight gas reservoir, considering that the fracture is a finite conductivity fracture, considering the inflow of reservoir fluids and the one-dimensional flow in the fracture, and ignoring the short unstable flow time in the fracture system, establish a dimensionless mathematical model for fluid seepage in the fracture;

[0010] Based on the dimensionless seepage mathematical model of a radial composite reservoir with a weak recharge boundary and the dimensionless seepage mathematical model of fluid in fractures, a seepage mathematical model of a tight gas reservoir with a weak recharge boundary is established;

[0011] Solve the seepage mathematical model of a tight gas reservoir with a weak recharge boundary to obtain the bottom-hole pressure solution of the gas well under this model, calculate its derivative, depict the pressure and its derivative curves in a double-logarithmic coordinate system, and obtain the well test curve;

[0012] Based on the well test curve, conduct a sensitivity factor analysis on the well test model of a tight gas reservoir with a weak recharge boundary.

[0013] Preferably, for the method described above, the assumption conditions of the fracturing well test physical model of a tight gas reservoir with a weak recharge boundary are as follows:

[0014] 1) The tight gas reservoir is a homogeneous gas reservoir with a circular closed boundary, the gas reservoir caprock and bottom plate are both closed, and the initial pressures at each point are the same;

[0015] 2) The fracturing fracture has finite conductivity and vertically penetrates the entire reservoir, is symmetric with the wellbore, and the flow at both ends of the fracture is ignored;

[0016] 3) The fluid in the tight gas reservoir is a slightly compressible fluid, with isothermal single-phase Darcy flow, and the capillary force and gravity effects are not considered;

[0017] 4) The product of the gas viscosity and the compressibility coefficient is a constant value;

[0018] 5) The gas well in the tight gas reservoir produces at a constant rate, the original reservoir supplies to the fracturing reconstruction area, and the fluid first flows from the reservoir into the fracture and then from the fracture into the wellbore.

[0019] Preferably, for the method described above, the following improvements are made to the seepage mathematical model of a tight gas reservoir with a weak recharge boundary:

[0020] Consider the external fluid recharge area and add a mass conservation equation for the recharge area;

[0021] Consider the radial composite reservoir formed by the physical property differences between the inner and outer areas and add an interface condition equation between the inner and outer areas;

[0022] Consider the weak recharge boundary and add an additional term containing the recharge factor at the interface between the inner and outer areas in the interface condition equation between the inner and outer areas.

[0023] Preferably, for the method described above, the specific process of solving the seepage mathematical model of a tight gas reservoir with a weak recharge boundary is as follows:

[0024] Using the Laplace transform, introducing the Green's function and the modified Bessel function, and applying the Duhamel method to solve the seepage mathematical model of a tight gas reservoir with a weak recharge boundary to obtain the bottom-hole pressure solution of the gas well under this model.

[0025] In the method described above, preferably, the sensitive factors include: fracture conductivity, inner zone radius, outer zone radius, interface recharge factor, mobility ratio between the inner and outer zones, and fracture half-length.

[0026] In the method described above, preferably, the dimensionless seepage mathematical model of a radial composite reservoir with a weak recharge boundary includes: inner zone mass conservation equation, outer zone mass conservation equation, inner boundary condition, outer boundary condition, initial condition, and interface condition between the inner and outer zones; the dimensionless seepage mathematical model of the fluid in the fracture includes: fracture seepage equation, inner boundary condition, and outer boundary condition.

[0027] In the method described above, preferably, the well test physical model of a tight gas reservoir with a weak recharge boundary includes: production wellbore, fractured fracture, fractured reformed area, and fluid recharge area. The production wellbore is located within the fractured fracture, the fractured reformed area surrounds the outside of the fractured fracture, and the fluid recharge area surrounds the outside of the fractured reformed area.

[0028] A second aspect of the present invention provides a well test analysis device for a tight gas reservoir with a weak recharge boundary. The device is based on establishing a well test model for a tight gas reservoir with a weak recharge boundary. The well test model for a tight gas reservoir includes a well test physical model and a seepage mathematical model for a tight gas reservoir, and includes:

[0029] A first processing unit for establishing a well test physical model of a tight gas reservoir with a weak recharge boundary based on the interface recharge factor and the external fluid recharge area;

[0030] A second processing unit for establishing a dimensionless seepage mathematical model of a radial composite reservoir with a weak recharge boundary based on the well test physical model of a tight gas reservoir and the seepage mathematical model of a finite conductivity fractured well;

[0031] A third processing unit for establishing a dimensionless seepage mathematical model of the fluid in the fracture based on the well test physical model of a tight gas reservoir, considering the fractured fracture as a finite conductivity fracture, considering the inflow of reservoir fluid and one-dimensional flow in the fracture, and ignoring the short-term unstable flow time of the fracture system;

[0032] A fourth processing unit for establishing a seepage mathematical model of a tight gas reservoir with a weak recharge boundary based on the dimensionless seepage mathematical model of a radial composite reservoir with a weak recharge boundary and the dimensionless seepage mathematical model of the fluid in the fracture;

[0033] A fifth processing unit for solving the seepage mathematical model of a tight gas reservoir with a weak recharge boundary to obtain the bottom-hole pressure solution of the gas well under this model, calculating its derivative, and depicting the pressure and its derivative curves in a double-logarithmic coordinate system to obtain the well test curve;

[0034] The sixth processing unit is configured to perform a sensitivity factor analysis on a well test model of a tight gas reservoir with a weak recharge boundary based on well test curves.

[0035] The third aspect of the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the well test analysis method for a tight gas reservoir with a weak recharge boundary described in any one of the above are implemented.

[0036] The fourth aspect of the present invention provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps of the well test analysis method for a tight gas reservoir with a weak recharge boundary described in any one of the above are implemented.

[0037] Due to the above technical solutions adopted by the present invention, it has the following advantages:

[0038] 1. For a tight gas reservoir with weak recharge influence, the present invention introduces a recharge factor at the interface between the inner and outer regions and considers the external fluid recharge area to quantitatively characterize the degree of weak recharge and clarify the fluid seepage law of the reservoir, thereby establishing a well test analysis model for a tight gas reservoir with a weak recharge boundary.

[0039] 2. The physical model in the present invention includes a production wellbore, a fracturing crack, a fracturing reformed area, a fluid recharge area, and other identification symbols. The physical model can intuitively show the distribution of fracturing cracks and reservoirs in a tight gas reservoir with a weak recharge boundary; the mathematical model includes a dimensionless seepage mathematical model for a radial composite reservoir and a dimensionless seepage mathematical model for the fluid in the crack. The mathematical model aims to quantitatively solve various model parameters; the model well test curve aims to analyze the fluid seepage characteristics of a tight gas reservoir with a weak recharge boundary; the model sensitivity factor analysis aims to clarify the main control influencing factors of the well test physical model of a tight gas reservoir with a weak recharge boundary.

[0040] 3. The present invention aims to reveal the seepage law of reservoir fluids in a tight gas reservoir with a weak recharge boundary and obtain more real and reliable production dynamic parameters of the tight gas reservoir. The present invention has important practical guiding significance for the development of unconventional gas reservoir seepage theory, fracturing evaluation, and efficient development. Description of the Drawings

[0041] Figure 1 is a schematic diagram of a well test physical model of a tight gas reservoir with a weak recharge boundary provided by an embodiment of the present invention;

[0042] Figure 2 is a schematic diagram of the characteristic curve of the well test physical model of a tight gas reservoir with a weak recharge boundary provided by this embodiment of the present invention;

[0043] Figure 3Schematic diagram for analyzing sensitive factors of well test physical model of tight gas reservoir with weak recharge boundary provided by this embodiment of the present invention;

[0044] Figure 4 Flow chart of the well test analysis method for tight gas reservoir with weak recharge boundary provided by this embodiment of the present invention. Detailed implementation manners

[0045] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0046] Well test analysis is a key technology in the development of unconventional gas fields. Field practices in some tight gas fields show that there is an external weak recharge phenomenon in the fracturing reformed area after gas wells are fractured, and the traditional well test analysis model for fractured wells is no longer applicable. In view of the tight gas reservoir with weak recharge influence, the present invention introduces a recharge factor at the interface between the inner and outer regions and considers the external fluid recharge area to quantitatively characterize the degree of weak recharge and clarify the fluid seepage law of the reservoir, so as to establish a set of well test analysis methods for tight gas reservoirs with weak recharge boundaries.

[0047] As Figure 1 shown, the well test analysis method for tight gas reservoirs with weak recharge boundaries involved in the present invention includes the following steps:

[0048] (1) Construction of the physical model

[0049] The well test physical model of the radial composite tight gas reservoir considering the weak recharge boundary is as Figure 1 shown. After the tight gas vertical well is fractured, the original reservoir is the fluid recharge area of the fractured reformed area, and due to the permeability difference between the reservoir fractured reformed area and the original reservoir, it shows a radial composite distribution. To quantitatively characterize the degree of weak fluid recharge in the fluid recharge area to the fractured reformed area, a recharge factor (β) is introduced at the interface between the two areas. Therefore, the physical model includes fracture, fractured reformed area (inner area), fluid recharge area (outer area) and other identification symbols. It can be seen from Figure 1 that the outlines of both the fractured reformed area and the fluid recharge area are circular, and the outer boundary of the fluid recharge area is a closed impermeable boundary.

[0050] According to the characteristics of tight gas reservoirs and the assumption conditions of conventional gas reservoir models, the assumption conditions for establishing the well test physical model of tight gas reservoirs with weak recharge boundaries are as follows:

[0051] 1) The tight gas reservoir is a homogeneous gas reservoir with a circular closed boundary, the gas reservoir caprock and bottom plate are both closed, and the initial pressures at each point are the same;

[0052] 2) The fracturing fracture has finite conductivity and vertically penetrates the entire reservoir, and is symmetrical with the wellbore. The flow at both ends of the fracture is ignored.

[0053] 3) The fluid in the tight gas reservoir is a slightly compressible fluid, and the isothermal single-phase Darcy seepage is considered. The capillary force and gravity effects are not considered.

[0054] 4) The product of the gas viscosity and the compressibility coefficient is a constant value.

[0055] 5) The gas well in the tight gas reservoir produces at a constant rate. The original reservoir supplies to the fracturing reformed area. The fluid first flows from the reservoir into the fracture and then from the fracture into the wellbore.

[0056] (2) Establishment and solution of the mathematical model

[0057] 1) Mathematical model of reservoir seepage

[0058] Based on the existing seepage mathematical model of a finite conductivity fractured well, a dimensionless seepage mathematical model of a radial composite reservoir considering a weak recharge boundary is established, as shown in Equation ①.

[0059]

[0060] In the formula, r D is the distance in the coordinate direction, dimensionless; ψ 1D and ψ 2D represent the pseudo - pressures in the inner and outer regions respectively, dimensionless; t D is the time, dimensionless; ω 12 and M 12 are the storage - capacity ratios and mobility ratios in the inner and outer regions respectively, dimensionless; q fD is the fracture flow - line density, dimensionless; β is the recharge factor at the interface between the inner and outer regions, dimensionless; r wD 、r fD 、r eD are the wellbore radius, the radius of the fracturing reformed area, and the radius of the original reservoir boundary respectively, dimensionless.

[0061] 2) Mathematical model of fracture seepage

[0062] Considering that the fracturing fracture has finite conductivity, considering the inflow of reservoir fluid and the one - dimensional flow in the fracture, and ignoring the short - term unstable flow time in the fracture system, the dimensionless seepage mathematical model of the fluid in the fracture can be obtained, as shown in Figure 2 or Equation ②.

[0063]

[0064] In the formula, ψ fD is the fracture pseudo - pressure, dimensionless; x D 、y Dis the coordinate direction distance, dimensionless; C FD is the fracture conductivity, dimensionless; W fD is the effective width of the fracturing fracture, dimensionless.

[0065] 3) Model solution

[0066] Using the Laplace transform, introducing the Green's function and the modified Bessel function, considering the wellbore storage effect and the skin effect, the bottom-hole pressure solution of the gas well is obtained by using the Duhamel method:

[0067]

[0068] In the formula, S is the wellbore skin factor, dimensionless; is the Laplace space solution of the bottom-hole pressure considering the wellbore storage effect and the skin effect; C D is the wellbore storage coefficient, dimensionless; u is the Laplace transform variable, complex number; is the bottom-hole pressure solution in the Laplace space.

[0069] Performing the inverse Laplace transform on Equation ③ can obtain the real-space bottom-hole pressure solution ψ wD (t D , S, C D ).

[0070] (3) Analysis of model characteristic curves

[0071] According to the bottom-hole pressure solution of the fractured vertical well in the radial composite tight gas reservoir considering the weak recharge boundary, the well test curve of this model can be obtained. The basic parameters are shown in Table 1.

[0072] Table 1 Basic parameter table

[0073]

[0074]

[0075] The typical pressure drawdown well test curve of the fractured vertical well in the radial composite tight gas reservoir considering the weak recharge boundary is obtained. See Figure 3 .

[0076] According to the characteristics of the pressure difference derivative curve, the flow stages of the well test model curve are divided as follows:

[0077] 1) Wellbore storage effect and skin effect stage: In this stage, the pressure difference curve and the pressure difference derivative curve coincide and the slope is 1. After the coincidence section, it shows a "hump" characteristic, and the height of the "hump" depends on the skin factor C D e 2S value.

[0078] 2) Fracture bilinear flow stage: In this stage, the fluid flows linearly from the fracturing reformed area to the fracture and then linearly from the fracture to the wellbore, showing bilinear flow. At this time, both the pressure and the slope of the pressure derivative are 1 / 4.

[0079] 3) Formation linear flow stage: In this stage, the flow in the fracture tends to be stable, and the pressure change is mainly controlled by the linear flow in the fracturing reformed area. At this time, both the pressure and the slope of the pressure derivative are 1 / 2.

[0080] 4) Inner region radial flow stage: In this stage, within the scope of the fracturing reformed area, the fluid reaches radial flow, and a horizontal section appears in the pressure derivative.

[0081] 5) Interface recharge stage between the inner and outer regions: The pressure difference and its derivative curve show the characteristics of pseudo-steady state flow. In the later stage, the slopes of both the pressure difference and its derivative curve are 1. The interface is like a pseudo-boundary, and at the same time, the derivative curve shows a "hump". The height of the "hump" is mainly controlled by the interface recharge factor β between the inner and outer regions.

[0082] 6) Outer region radial flow stage: In the outer region, the fluid reaches radial flow, and a horizontal section appears in the pressure derivative.

[0083] 7) Pseudo-steady state flow stage: The pressure drop reaches the closed boundary of the gas reservoir, and the pressure difference and the pressure difference derivative curve merge and turn up, showing a characteristic with a slope of 1.

[0084] According to the division results, it can be seen that the well test physical model curve of the tight gas reservoir with a weak recharge boundary shows the characteristics of pseudo-steady state flow with a slope of 1 in two stages. Among them, the first stage reflects the inner region boundary, and the second stage reflects the outer region boundary.

[0085] (4) Analysis of model sensitive factors

[0086] To further analyze the characteristics of the well test physical model of the tight gas reservoir with a weak recharge boundary, a sensitivity analysis of the characteristic curve of the well test model was carried out from five aspects: fracture conductivity, inner region radius, outer region radius, interface recharge factor, and mobility ratio between the inner and outer regions. Each factor takes three values, and the differences of the model characteristic curves under different values are compared and analyzed. The results of the analysis of model sensitive factors are shown in Figure 4 . The analysis results show that the fracture conductivity, interface recharge factor, and mobility ratio between the inner and outer regions are the main influencing factors of the model characteristic curve.

[0087] Based on the above analysis, the present invention provides a well test model for a tight gas reservoir with a weak recharge boundary, which can effectively perform dynamic inversion on the tight gas reservoir with a weak recharge boundary to obtain more real and reliable dynamic parameters and reveal the seepage law of reservoir fluids in the tight gas reservoir with a weak recharge boundary.

[0088] In a second aspect of the present invention, a well test analysis device for a tight gas reservoir with a weak recharge boundary is provided. The device is based on establishing a well test model for a tight gas reservoir with a weak recharge boundary. The well test model for a tight gas reservoir includes a physical model for well testing of a tight gas reservoir and a mathematical model for seepage in a tight gas reservoir, and includes:

[0089] A first processing unit for establishing a physical model for well testing of a tight gas reservoir with a weak recharge boundary based on an interface recharge factor and an external fluid recharge area;

[0090] A second processing unit for establishing a dimensionless seepage mathematical model for a radial composite reservoir with a weak recharge boundary based on the physical model for well testing of a tight gas reservoir and the mathematical model for seepage in a finite conductivity fractured well;

[0091] A third processing unit for establishing a dimensionless seepage mathematical model for the fluid in the fracture based on the physical model for well testing of a tight gas reservoir, considering the fractured well as a finite conductivity fracture, considering the inflow of reservoir fluid and the one-dimensional flow in the fracture, and ignoring the short transient unstable flow time in the fracture system;

[0092] A fourth processing unit for establishing a mathematical model for seepage in a tight gas reservoir with a weak recharge boundary based on the dimensionless seepage mathematical model for a radial composite reservoir with a weak recharge boundary and the dimensionless seepage mathematical model for the fluid in the fracture;

[0093] A fifth processing unit for solving the mathematical model for seepage in a tight gas reservoir with a weak recharge boundary to obtain the bottom-hole pressure solution of the gas well under this model, calculating its derivative, and depicting the pressure and its derivative curves in a double logarithmic coordinate system to obtain the well test curve;

[0094] A sixth processing unit for performing a sensitivity factor analysis on the well test model for a tight gas reservoir with a weak recharge boundary based on the well test curve.

[0095] In a third aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method for analyzing a well test of a tight gas reservoir with a weak recharge boundary described in any one of the above are implemented.

[0096] In a fourth aspect of the present invention, a computer device is provided, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps of the method for analyzing a well test of a tight gas reservoir with a weak recharge boundary described in any one of the above are implemented.

[0097] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to specific embodiments. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and combinations of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device generate a means for implementing the functions specified in one or more flows and / or blocks. Figure 1 in one or more flows and / or blocks Figure 1 or in one or more blocks.

[0098] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including an instruction means that implements the functions specified in one or more flows and / or blocks Figure 1 in one or more flows and / or blocks Figure 1 or in one or more blocks.

[0099] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more flows and / or blocks Figure 1 in one or more flows and / or blocks Figure 1 or in one or more blocks.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A well test analysis method for a tight gas reservoir with a weak recharge boundary, the method being based on establishing a well test model for a tight gas reservoir with a weak recharge boundary, the well test model for a tight gas reservoir including a physical model for well testing of a tight gas reservoir and a mathematical model for seepage flow in a tight gas reservoir, characterized in that It includes the following steps: Based on the interface recharge factor and the external fluid recharge area, establish a physical well test model for a tight gas reservoir with a weak recharge boundary; Based on the physical well test model of the tight gas reservoir and the seepage mathematical model of a finite conductivity fractured well, establish a dimensionless seepage mathematical model for a radial composite reservoir with a weak recharge boundary; Based on the physical well test model of the tight gas reservoir, considering the fractured fracture as a finite conductivity fracture, considering the inflow of reservoir fluid and the one-dimensional flow in the fracture, and ignoring the short unstable flow time in the fracture system, establish a dimensionless seepage mathematical model for the fluid in the fracture; Based on the dimensionless seepage mathematical model of the radial composite reservoir with a weak recharge boundary and the dimensionless seepage mathematical model of the fluid in the fracture, establish a seepage mathematical model for the tight gas reservoir with a weak recharge boundary; Solve the seepage mathematical model of the tight gas reservoir with a weak recharge boundary to obtain the bottom-hole pressure solution of the gas well under this model, calculate its derivative, and depict the pressure and its derivative curves in a double logarithmic coordinate system to obtain the well test curve; Based on the well test curve, conduct a sensitivity factor analysis on the well test model of the tight gas reservoir with a weak recharge boundary.

2. The method according to claim 1, characterized in that The assumptions of the physical model of the fracturing well test for the tight gas reservoir with a weak recharge boundary are as follows: 1) The tight gas reservoir is a homogeneous gas reservoir with a circular closed boundary, the gas reservoir caprock and bottom plate are both closed, and the initial pressures at each point are the same; 2) The fractured fracture has finite conductivity and vertically penetrates the entire reservoir, and is symmetrical with the wellbore, ignoring the flow at both ends of the fracture; 3) The fluid in the tight gas reservoir is a slightly compressible fluid, with isothermal single-phase Darcy seepage, and the capillary force and gravity effects are not considered; 4) The product of the gas viscosity and the compressibility coefficient is a constant value; 5) The gas well in the tight gas reservoir produces at a constant rate, the original reservoir supplies to the fracturing reformed area, and the fluid first flows from the reservoir into the fracture and then from the fracture into the wellbore.

3. The method according to claim 1, wherein The following improvements are made to the seepage mathematical model of the tight gas reservoir with a weak recharge boundary: Consider the external fluid recharge area and add a mass conservation equation for the recharge area; Consider the radial composite reservoir formed by the physical property differences between the inner and outer areas and add an interface condition equation between the inner and outer areas; Consider the weak recharge boundary and add an additional term containing the interface recharge factor between the inner and outer areas to the interface condition equation between the inner and outer areas.

4. The method according to claim 1, wherein The specific process of solving the seepage mathematical model of the tight gas reservoir with a weak recharge boundary is as follows: Use the Laplace transform, introduce the Green's function and the modified Bessel function, and use the Duhamel method to solve the seepage mathematical model of the tight gas reservoir with a weak recharge boundary to obtain the bottom-hole pressure solution of the gas well under this model.

5. The method according to claim 1, characterized in that, The sensitivity factors include: fracture conductivity, inner zone radius, outer zone radius, interface recharge factor, mobility ratio between the inner and outer zones, and fracture half-length.

6. The method according to claim 1, characterized in that, The dimensionless seepage mathematical model of the radial composite reservoir with a weak recharge boundary includes: inner zone mass conservation equation, outer zone mass conservation equation, inner boundary condition, outer boundary condition, initial condition, and interface condition between the inner and outer zones; the dimensionless seepage mathematical model of the fluid in the fracture includes: fracture seepage equation, inner boundary condition, and outer boundary condition.

7. The method according to claim 1, wherein The well test physical model of a tight gas reservoir with a weak recharge boundary includes: a production wellbore, a fractured crack, a fractured reformed area, and a fluid recharge area. The production wellbore is located within the fractured crack, the fractured reformed area surrounds the outside of the fractured crack, and the fluid recharge area surrounds the outside of the fractured reformed area.

8. A well test analysis device for a tight gas reservoir with a weak recharge boundary, which is based on establishing a well test model for a tight gas reservoir with a weak recharge boundary. The well test model for a tight gas reservoir includes a physical model for well testing of a tight gas reservoir and a mathematical model for seepage flow in a tight gas reservoir, and is characterized in that, including: a first processing unit for establishing a well test physical model of a tight gas reservoir with a weak recharge boundary based on the interface recharge factor and the external fluid recharge area; a second processing unit for establishing a dimensionless seepage mathematical model of a radial composite reservoir with a weak recharge boundary based on the well test physical model of the tight gas reservoir and the seepage mathematical model of a finite conductivity fractured well; a third processing unit for establishing a dimensionless seepage mathematical model of the fluid within the fracture based on the well test physical model of the tight gas reservoir, considering the fractured crack as a finite conductivity fracture, considering the inflow of reservoir fluid and the one-dimensional flow within the fracture, and ignoring the short unstable flow time of the fracture system; a fourth processing unit for establishing a seepage mathematical model of a tight gas reservoir with a weak recharge boundary based on the dimensionless seepage mathematical model of a radial composite reservoir with a weak recharge boundary and the dimensionless seepage mathematical model of the fluid within the fracture; a fifth processing unit for solving the seepage mathematical model of a tight gas reservoir with a weak recharge boundary to obtain the bottom hole pressure solution of the gas well under this model, calculating its derivative, and depicting the pressure and its derivative curves in a double logarithmic coordinate system to obtain the well test curve; a sixth processing unit for performing a sensitivity factor analysis on the well test model of a tight gas reservoir with a weak recharge boundary based on the well test curve.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, the steps of the well test analysis method for a tight gas reservoir with a weak recharge boundary described in any one of claims 1-7 are implemented.

10. A computer device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, the steps of the well test analysis method for a tight gas reservoir with a weak recharge boundary described in any one of claims 1-7 are implemented.

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