Method for calculating effective volume of natural fracture network around well of fractured reservoir and related equipment

Abstract

The invention relates to the technical field of well test interpretation, and discloses a method for calculating the effective volume of a natural fracture network around a fractured reservoir well and related equipment, and the method comprises the following steps: by taking actual data of a fractured reservoir downhole pressure test as a support, drawing a well test curve of a test well and converting the well test curve into a rectangular coordinate curve, constructing an analysis basis fitting the real seepage characteristics of the reservoir, and calculating the effective volume of the natural fracture network around the fractured reservoir well. And limitation of non-uniform distribution of a traditional homogeneous hypothesis model and actual reservoir fractures is avoided. The effective volume of the natural fracture network is directly calculated based on a rectangular coordinate curve, the problem of large indirect calculation error of a traditional method is solved, the effective fracture network scale around the well can be accurately represented, and reliable technical support is provided for defining dominant reservoir distribution, analyzing productivity main control factors and accurately calculating oil and gas geological reserves. And fine evaluation and development of the fractured oil and gas reservoir are facilitated.

Description

Technical Field

[0001] This invention relates to the field of well test interpretation technology, specifically to a method and related equipment for calculating the effective volume of natural fracture networks around a fractured reservoir well. Background Technology

[0002] As oil and gas reservoir exploration and development deepens, the development of shallow conventional oil and gas reservoirs is gradually entering the late stage of exploration and development. Currently, the main goal for increasing oil and gas reserves and production lies in the development and utilization of unconventional and deep oil and gas reservoirs. These reservoirs are often artificially modified to form well-perimeter fracture networks or have naturally developed well-perimeter fracture networks. Of the world's currently confirmed reserves, fractured oil and gas reservoirs account for about one-fifth of the world's total reserves. In recent years, multiple fractured oil and gas reservoirs have been discovered in various locations. These reservoirs are often buried at great depths, or consist of volcanic rocks, metamorphic rocks, etc., and often have extremely poor matrix properties. The storage and seepage channels for oil and gas are secondary diagenetic fractures or weathering-tectonic fractures.

[0003] Therefore, for the aforementioned oil and gas reservoirs, complex fracture networks are often distributed around the well, forming the space for oil and gas accumulation and seepage. Accurately evaluating the effective fracture network volume around the well is of great significance for identifying the distribution of dominant reservoirs and the main factors controlling production capacity, conducting future production forecasting and optimizing production systems, and calculating oil and gas geological reserves.

[0004] In well test interpretation technology, previous studies have focused on matrix-fracture dual-porosity media models. For fractured reservoir well test interpretation models, homogeneity is often considered, meaning the fracture morphology is uniform and the fractures are evenly distributed within the matrix reservoir. Currently, dual-porosity media (pore and fracture) models based on this concept mainly include quasi-steady-state models, spherical models, and plate models. However, these models can only derive the reservoir capacity ratio and channeling coefficient to represent fracture development and the flow capacity of the matrix system to the fracture network, respectively. They cannot directly calculate the effective fracture volume, and the indirectly calculated fracture volume has large errors. Therefore, it is necessary to establish a well-perimeter effective fracture volume well test analysis technique based on the seepage mechanism of fractured reservoirs, providing a technical means for the refined evaluation of complex fractured oil and gas reservoirs. Summary of the Invention

[0005] This invention provides a method and related equipment for calculating the effective volume of natural fracture network around a fractured reservoir well, which solves the problem that the effective volume of fractures cannot be directly obtained and the fracture volume calculated indirectly has a large error.

[0006] To achieve the above objectives, the present invention provides the following technical solution: Methods for calculating the effective volume of natural fracture networks around fractured reservoirs include: Obtain downhole pressure test data for fractured reservoirs; Plot well test curves based on downhole pressure test data of fractured reservoirs; Identify the pseudo-steady flow stage based on the test well curves, and plot a rectangular coordinate curve based on the pseudo-steady flow stage time and pressure difference data. Linear regression based on rectangular coordinate curves is used to obtain the slope of the straight line, and the volume factor, comprehensive compressibility factor and actual wellhead production of fractured reservoirs are obtained. The effective volume of the natural fracture network around the wellhead of the fractured reservoir is calculated based on the straight slope, the actual production at the wellhead of the fractured reservoir, the volume factor, and the comprehensive compressibility factor.

[0007] A further improvement of this invention lies in the fact that the well test curves are plotted based on downhole pressure test data from fractured reservoirs as follows: If the test object of the downhole pressure test data of the fractured reservoir is an oil-water layer, the downhole pressure test data can be directly used to draw the data. If the downhole pressure test data for fractured reservoirs is used to test gas reservoirs, replace the downhole pressure test data with pseudo-pressure and then plot the well test curve. The pseudo-pressure is:

[0008] In the formula: atmospheric pressure ， For the original pressure, The deviation coefficient under the original conditions. The viscosity of the fluid under the original conditions. To simulate pressure, For pressure, For pressure p The corresponding viscosity is below. For pressure p The corresponding deviation coefficient is below.

[0009] A further improvement of this invention is that, for downhole pressure test data or simulated pressure during the fixed production stage, a double logarithmic curve of the production pressure difference and the logarithmic derivative of the production pressure difference with respect to production time is plotted, wherein the production pressure difference is the difference between the original pressure and the production pressure. For downhole pressure test data or simulated pressure during the shut-in phase after production, plot a double logarithmic curve of shut-in pressure differential and its logarithmic derivative with respect to shut-in time, where shut-in pressure differential is the difference between shut-in pressure and instantaneous shut-in pressure.

[0010] A further improvement of the present invention is that, The pseudo-steady flow stage is characterized by a dip in the logarithmic derivative of the production pressure difference with respect to time in the well test curve, followed by a straight line segment with a slope of 1.

[0011] A further improvement of this invention lies in the method for obtaining the volume factor and overall compressibility factor of fractured reservoirs as follows: Obtain formation fluid parameters and reservoir parameters of fractured reservoirs, and obtain volume factor and comprehensive compressibility factor based on formation fluid parameters and reservoir parameters of fractured reservoirs.

[0012] A further improvement of this invention lies in the method for obtaining the effective volume of the natural fracture network around the well based on the straight slope, the actual production rate of the fractured reservoir wellhead, the volume factor, and the comprehensive compressibility factor:

[0013] In the formula: q For actual output, B This is the volume factor. C t The overall compression coefficient is... The effective volume of the natural fracture network around the well. The slope of the line.

[0014] A system for calculating the effective volume of natural fracture networks around a fractured reservoir well includes: Data acquisition module: used to acquire downhole pressure test data of fractured reservoirs; First plotting module: used to plot well test curves based on downhole pressure test data of fractured reservoirs; The second plotting module is used to identify the quasi-steady flow stage based on the well test curves and to plot rectangular coordinate curves based on the quasi-steady flow stage time and pressure difference data. Regression Acquisition Module: Used to perform linear regression based on rectangular coordinate curves to obtain the slope of the straight line, and to obtain the volume factor, comprehensive compressibility factor and actual wellhead production of fractured reservoirs; Calculation module: Used to calculate the effective volume of the natural fracture network around the wellhead of a fractured reservoir based on the slope of the straight line, the actual production at the wellhead of the fractured reservoir, the volume factor, and the comprehensive compressibility factor.

[0015] A computer device includes a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of a method for calculating the effective volume of natural fracture networks around a fractured reservoir well.

[0016] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of a method for calculating the effective volume of natural fracture networks around a fractured reservoir well.

[0017] A computer program product includes a computer program that, when executed by a processor, implements the steps of a method for calculating the effective volume of natural fracture networks around a fractured reservoir well.

[0018] Compared with existing technologies, this invention has the following advantages: This invention provides a method for calculating the effective volume of the natural fracture network around a fractured reservoir. Based on downhole pressure test data of fractured reservoirs, it constructs an analytical foundation that closely reflects the actual seepage characteristics of the reservoir by plotting well test curves and converting them into rectangular coordinate curves, thus avoiding the limitations of traditional homogeneous assumption models and the discrepancies between actual reservoir fracture distribution. By directly calculating the effective volume of the natural fracture network based on rectangular coordinate curves, it solves the problem of large errors in indirect calculations using traditional methods. This method can accurately characterize the scale of the effective fracture network around the well, providing reliable technical support for analyzing the main factors controlling production capacity and accurately calculating oil and gas geological reserves, thus contributing to the refined evaluation and development of fractured oil and gas reservoirs.

[0019] Furthermore, based on seepage theory, by identifying the quasi-steady flow stage, linear regression analysis of the unstable test data during the quasi-steady flow stage is conducted, thereby accurately calculating the effective volume of natural fractures around the well based on the slope and reservoir parameters. Compared with conventional methods, the calculation method is simpler and faster, considers fewer parameters, is easier to obtain, and yields more accurate results. Attached Figure Description

[0020] Figure 1 This is a flowchart of the method for calculating the effective volume of natural fracture network around a fractured reservoir according to the present invention. Figure 2 This invention provides an embodiment of the method for plotting a well test curve using shut-in pressure test data. Figure 3 The linear regression curve is the test data of the simulated stable flow stage in an embodiment of the present invention. Figure 4 This is a well test curve diagram of an embodiment of the present invention; Figure 5 This is a linear regression curve of test data for another pseudo-steady flow stage in an embodiment of the present invention; Figure 6 This is a block diagram of the effective volume calculation system for the natural fracture network around a fractured reservoir well, as described in this invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0025] like Figure 1 As shown, this invention provides a method for calculating the effective volume of natural fracture networks around a fractured reservoir well, including: S1 acquires downhole pressure test data for fractured reservoirs; S2 plots well test curves based on downhole pressure test data of fractured reservoirs; S3 identifies the pseudo-steady flow stage based on the test well curves and plots a rectangular coordinate curve based on the pseudo-steady flow stage time and pressure difference data. S4 uses linear regression based on rectangular coordinate curves to obtain the slope of the straight line, and then obtains the volume factor, comprehensive compressibility factor and actual wellhead production of fractured reservoirs. S5 calculates the effective volume of the natural fracture network around the wellhead of the fractured reservoir based on the straight slope, the actual production at the wellhead of the fractured reservoir, the volume factor, and the comprehensive compressibility factor.

[0026] Based on downhole pressure test data of fractured reservoirs, this study constructs an analytical foundation that closely reflects the actual seepage characteristics of the reservoir by plotting well test curves and converting them into rectangular coordinate curves. This avoids the limitations of traditional homogeneous assumption models that differ from the actual fracture distribution in reservoirs. The effective volume of the natural fracture network is directly calculated based on the rectangular coordinate curves, solving the problem of large errors in indirect calculations using traditional methods. This accurately characterizes the effective fracture network size around the well, providing reliable technical support for analyzing key factors controlling production capacity and accurately calculating oil and gas geological reserves, thus contributing to the refined evaluation and development of fractured oil and gas reservoirs.

[0027] The detailed steps are as follows: The specific steps for plotting well test curves based on downhole pressure test data of fractured reservoirs are as follows: If the downhole pressure test data of a fractured reservoir is used to test an oil-water layer, the downhole pressure test data can be used to plot the well test curve.

[0028] If the downhole pressure test data for fractured reservoirs is used to test gas reservoirs, replace the downhole pressure test data with pseudo-pressure and then plot the well test curve. The pseudo-pressure is: (1).

[0029] In the formula: Atmospheric pressure, MPa; p i The original pressure is in MPa. The deviation coefficient under the original conditions is dimensionless. The viscosity of the fluid under the original conditions is given in mPa·s. The simulated pressure is in MPa. For pressure p The corresponding viscosity is below. For pressure p The corresponding deviation coefficient is below. For pressure.

[0030] For downhole pressure test data or simulated pressure during the production ramp-up phase, plot the production pressure differential. Logarithmic derivative of production pressure differential Regarding production time t The double logarithmic curve, in which the production pressure difference For the original pressure p i With production pressure difference; For downhole pressure test data or simulated pressure during the post-production shut-in phase, plot the shut-in pressure differential. Logarithmic derivative of shut-in pressure difference Regarding shut-in time Δ t The double logarithmic curve, in which the shut-in pressure difference For shut-in pressure Instantaneous pressure upon shutting in the well p ws0 difference; The specific steps for plotting a rectangular coordinate curve based on the well test curves are as follows: (1) Identify the pseudo-steady flow stage based on the derivative curve in the test well curve.

[0031] When a large-scale natural fracture network exists near the wellbore, crossflow characteristics are likely to occur. That is, the logarithmic derivative of the pressure difference with respect to time in the test well curve will show a dip, and then a straight line segment with a slope of 1 will gradually appear, which is the pseudo-steady flow stage.

[0032] (2) Use the time and pressure difference data corresponding to the pseudo-steady flow stage in the test well curve to draw a rectangular coordinate curve.

[0033] The specific steps for calculating the effective volume of the natural fracture network around a fractured reservoir well based on rectangular coordinate curves are as follows: The slope of the straight line is obtained by performing linear regression on the rectangular coordinate curve. .

[0034] For downhole pressure test data during the fixed production phase, the pressure or differential pressure changes linearly with time. The wellhead production during this phase originates from the elastic energy of the natural fracture network region; therefore: (2).

[0035] Due to production pressure, For production time, The effective volume of the natural fracture network around the well. C t The overall compression coefficient is... B This is the volume factor. q This represents the actual output.

[0036] After the points are: (3).

[0037] in, The initial pressure difference. To produce pressure differential.

[0038] It can be seen that the curve of pressure difference changing with time is a straight line in a rectangular coordinate system. Let the slope be... m Then equation (3) can be written as: (4).

[0039] in The slope of the line.

[0040] For the post-production shut-in phase: (5) In the formula: Production time before well shut-in. For the shut-in pressure differential, This refers to the well shut-in time.

[0041] Sufficient production time before well shut-in >>Δ t Equation (5) can be approximated as: (6) Therefore, equation (4) can also be written as: (7) in: (8) The effective volume of the natural seam network can be calculated based on the slope: (9) In the formula: For actual output, m 3 / d; B m is the volume index. 3 / m 3 ; C t The overall compressibility factor is expressed in MPa. -1 ; V f The effective volume of the natural fracture network around the well is m. 3 .

[0042] Another embodiment of the present invention provides a method for calculating the effective volume of natural fracture networks around a fractured reservoir well, including: acquiring downhole pressure test data of the fractured reservoir, and plotting well test curves based on the downhole pressure test data of the fractured reservoir, such as... Figure 2 As shown; Plot a rectangular coordinate curve based on the well test curves from the test wells; (1) Based on the characteristic that the slope of the derivative curve in the well test curve is 1, the pseudo-steady flow stage is identified. Figure 2 .

[0043] (2) Plot a rectangular coordinate curve using the time and pressure difference data corresponding to the pseudo-steady flow stage (see figure). Figure 3 Linear regression yielded a line with a slope m of 0.001.

[0044] The effective volume of the natural fracture network around a fractured reservoir well is calculated based on rectangular coordinate curves.

[0045] The effective volume of the natural fracture network is calculated based on the pressure change formula during the quasi-steady flow stage, involving parameter values ​​such as oil well production. q It is 157.4m 3 / d, volume index B It is 1.052m 3 / m 3 Overall compression coefficient C t 0.0021 MPa -1 Therefore, the effective volume of the natural seam mesh is: (10).

[0046] Another embodiment of the present invention provides a method for calculating the effective volume of natural fracture networks around a fractured reservoir well, including: acquiring downhole pressure test data of the fractured reservoir, and plotting well test curves based on the downhole pressure test data of the fractured reservoir, such as... Figure 4 As shown; Plot a rectangular coordinate curve based on the well test curves from the test wells; (1) Based on the characteristic that the slope of the derivative curve in the well test curve is 1, the pseudo-steady flow stage is identified. Figure 4 .

[0047] (2) Plot a rectangular coordinate curve using the time and pressure difference data corresponding to the pseudo-steady flow stage (see figure). Figure 5 Linear regression yielded a line with a slope m of 0.0007.

[0048] Calculate the effective volume of the natural fracture network around a fractured reservoir well based on rectangular coordinate curves; The effective volume of the natural fracture network is calculated based on the pressure change formula during the quasi-steady flow stage, involving parameter values ​​such as gas well production. q 648299m 3 / d, volume factor B It is 0.0027m 3 / m 3 Overall compression coefficient C t 0.0062 MPa -1 Fluid viscosity under original conditions μ i The value is 0.0353 mPa·s. Therefore, the effective volume of the natural seam mesh is... (11).

[0049] like Figure 6 As shown, the present invention also provides a system for calculating the effective volume of natural fracture networks around fractured reservoir wells, including: Data acquisition module: used to acquire downhole pressure test data of fractured reservoirs; First plotting module: used to plot well test curves based on downhole pressure test data of fractured reservoirs; The second plotting module is used to identify the quasi-steady flow stage based on the well test curves and to plot rectangular coordinate curves based on the quasi-steady flow stage time and pressure difference data. Regression Acquisition Module: Used to perform linear regression based on rectangular coordinate curves to obtain the slope of the straight line, and to obtain the volume factor, comprehensive compressibility factor and actual wellhead production of fractured reservoirs; Calculation module: Used to calculate the effective volume of the natural fracture network around the wellhead of a fractured reservoir based on the slope of the straight line, the actual production at the wellhead of the fractured reservoir, the volume factor, and the comprehensive compressibility factor.

[0050] In the first plotting module, the well test curves of the test wells are plotted based on the wellbore pressure test data of fractured reservoirs as follows: If it is an oil-water layer, the plotting is directly drawn using downhole pressure test data. If it is a gas reservoir, replace the downhole pressure test data with the simulated pressure and then plot it. The simulated pressure is: (12).

[0051] In the formula: atmospheric pressure ， For the original pressure, z i The deviation coefficient under the original conditions. The viscosity of the fluid under the original conditions. To simulate pressure, For pressure p The corresponding viscosity is below. For pressure p The corresponding deviation coefficient is below. For pressure.

[0052] In the first plotting module, for the pressure measurement data during the fixed production stage, a double logarithmic curve of the production pressure difference and the logarithmic derivative of the production pressure difference with respect to the production time is plotted, where the production pressure difference is the difference between the original pressure and the production pressure. For the pressure measurement data during the shut-in phase after production, a double logarithmic curve of shut-in pressure difference and its logarithmic derivative with respect to shut-in time is plotted, where shut-in pressure difference is the difference between shut-in pressure and instantaneous shut-in pressure.

[0053] In the second plotting module, the specific steps for plotting a rectangular coordinate curve based on the well test curve are as follows: Identify the pseudo-steady flow stage based on the test well curves, and plot a rectangular coordinate curve based on the pseudo-steady flow stage time and pressure difference data. The pseudo-steady flow stage is characterized by a dip in the derivative curve of the test well, followed by a straight line segment with a slope of 1.

[0054] In the calculation module, the specific steps for calculating the effective volume of the natural fracture network around a fractured reservoir well based on a rectangular coordinate curve are as follows: Based on the rectangular coordinate curve, linear regression is performed to obtain the slope of the straight line. Obtain formation fluid parameters and reservoir parameters of fractured reservoirs, obtain volume factor and comprehensive compressibility factor based on formation fluid parameters and reservoir parameters of fractured reservoirs, and obtain the actual production of fractured reservoir wellhead; The effective volume of the natural fracture network around the well is obtained based on the straight slope, the actual production at the wellhead of the fractured reservoir, the volume factor, and the comprehensive compressibility factor.

[0055] In the calculation module, the method for obtaining the effective volume of the natural fracture network around the well based on the straight slope, the actual production rate of the fractured reservoir wellhead, the volume factor, and the comprehensive compressibility factor is as follows: (13).

[0056] In the formula: q For actual output, B This is the volume factor. C t The overall compression coefficient is... The effective volume of the natural fracture network around the well. The slope of the line.

[0057] A computer device is provided according to an embodiment of the present invention. This computer device includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the various method embodiments described above. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the various device embodiments described above.

[0058] The computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention.

[0059] The computer device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The computer device may include, but is not limited to, a processor and memory.

[0060] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0061] The memory can be used to store the computer program and / or module, and the processor implements various functions of the computer device by running or executing the computer program and / or module stored in the memory, and by calling the data stored in the memory.

[0062] If the modules / units integrated into the computer device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.

[0063] Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, it can implement the steps of the above method embodiments.

[0064] The computer program includes computer program code, which may be in the form of source code, object code, executable file, or some intermediate form.

[0065] The computer-readable medium may include any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory, random access memory, electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium may be appropriately added to or subtracted according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media may not include electrical carrier signals and telecommunication signals.

[0066] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art, guided by the specification, can make many other modifications without departing from the scope of the claims of the present invention, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A method for calculating the effective volume of natural fracture network around a fractured reservoir well, characterized in that, include: Obtain downhole pressure test data for fractured reservoirs; Plot well test curves based on downhole pressure test data of fractured reservoirs; Identify the pseudo-steady flow stage based on the test well curves, and plot a rectangular coordinate curve based on the pseudo-steady flow stage time and pressure difference data. Linear regression based on rectangular coordinate curves is used to obtain the slope of the straight line, and the volume factor, comprehensive compressibility factor and actual wellhead production of fractured reservoirs are obtained. The effective volume of the natural fracture network around the wellhead of the fractured reservoir is calculated based on the straight slope, the actual production at the wellhead of the fractured reservoir, the volume factor, and the comprehensive compressibility factor.

2. The method for calculating the effective volume of natural fracture network around a fractured reservoir well according to claim 1, characterized in that, The specific well test curves for fractured reservoirs, plotted based on downhole pressure test data, are as follows: If the test object of the downhole pressure test data of the fractured reservoir is an oil-water layer, the downhole pressure test data can be directly used to draw the data. If the downhole pressure test data for fractured reservoirs is used to test gas reservoirs, replace the downhole pressure test data with pseudo-pressure and then plot the well test curve. The pseudo-pressure is: In the formula: atmospheric pressure ， For the original pressure, The deviation coefficient under the original conditions. The viscosity of the fluid under the original conditions. To simulate pressure, For pressure, For pressure p The corresponding viscosity is below. For pressure p The corresponding deviation coefficient is below.

3. The method for calculating the effective volume of natural fracture network around a fractured reservoir well according to claim 2, characterized in that, For downhole pressure test data or simulated pressure during the fixed production stage, plot a double logarithmic curve of production pressure difference and the logarithmic derivative of production pressure difference with respect to production time, where production pressure difference is the difference between the original pressure and the production pressure; For downhole pressure test data or simulated pressure during the shut-in phase after production, plot a double logarithmic curve of shut-in pressure differential and its logarithmic derivative with respect to shut-in time, where shut-in pressure differential is the difference between shut-in pressure and instantaneous shut-in pressure.

4. The method for calculating the effective volume of natural fracture network around a fractured reservoir well according to claim 1, characterized in that, The pseudo-steady flow stage is characterized by a dip in the logarithmic derivative of the production pressure difference with respect to time in the well test curve, followed by a straight line segment with a slope of 1.

5. The method for calculating the effective volume of natural fracture network around a fractured reservoir well according to claim 1, characterized in that, The methods for obtaining the volume factor and overall compressibility factor of fractured reservoirs are as follows: Obtain formation fluid parameters and reservoir parameters of fractured reservoirs, and obtain volume factor and comprehensive compressibility factor based on formation fluid parameters and reservoir parameters of fractured reservoirs.

6. The method for calculating the effective volume of natural fracture network around a fractured reservoir well according to claim 1, characterized in that, The method for obtaining the effective volume of the natural fracture network around the well based on the linear slope, the actual production rate at the wellhead of the fractured reservoir, the volume factor, and the comprehensive compressibility factor is as follows: In the formula: q For actual output, B This is the volume factor. C t The overall compression coefficient is... The effective volume of the natural fracture network around the well. The slope of the line.

7. A system for calculating the effective volume of natural fracture networks around a fractured reservoir well, characterized in that, include: Data acquisition module: used to acquire downhole pressure test data of fractured reservoirs; First plotting module: used to plot well test curves based on downhole pressure test data of fractured reservoirs; The second plotting module is used to identify the quasi-steady flow stage based on the well test curves and to plot rectangular coordinate curves based on the quasi-steady flow stage time and pressure difference data. Regression Acquisition Module: Used to perform linear regression based on rectangular coordinate curves to obtain the slope of the straight line, and to obtain the volume factor, comprehensive compressibility factor and actual wellhead production of fractured reservoirs; Calculation module: Used to calculate the effective volume of the natural fracture network around the wellhead of a fractured reservoir based on the slope of the straight line, the actual production at the wellhead of the fractured reservoir, the volume factor, and the comprehensive compressibility factor.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method for calculating the effective volume of natural fracture network around a fractured reservoir well as described in any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the method for calculating the effective volume of natural fracture network around a fractured reservoir as described in any one of claims 1-6.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the method for calculating the effective volume of natural fracture network around a fractured reservoir as described in any one of claims 1-6.

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