A method and related equipment for calculating the length of large-scale natural cracks

Abstract

This invention relates to the field of well test interpretation technology, and discloses a method and related equipment for calculating the length of large-scale natural fractures. By establishing a mathematical model of well test in a naturally fractured reservoir, calculating the real-time bottom hole pressure, and plotting the interpretation curve of the well test in the naturally fractured reservoir, the theoretical bottom hole pressure is obtained by combining the real-time bottom hole pressure and the interpretation curve, and the theoretical well test curve is plotted. Finally, the natural fracture length is obtained by fitting the theoretical and measured curves. This method overcomes the limitation of uniform fracture distribution in conventional models, is suitable for deep gas reservoirs with poor matrix properties and strong fracture heterogeneity, and avoids the problem of only being able to obtain equivalent parameters and interpreting parameters that do not reflect reality. It accurately characterizes the fracture development state and improves the accuracy of well test interpretation.

Description

Technical Field

[0001] This invention belongs to the field of well test interpretation technology, specifically a method and related equipment for calculating the length of large-scale natural fractures. Background Technology

[0002] Deep natural gas reservoirs are mostly narrow, strip-shaped anticlines formed by plate collision and compression. Natural fractures are concentrated in the axial part of the anticline to form highly conductive strips. The fracture development is reduced on both sides due to the decrease in reservoir deformation. Wells in the axial part are easy to produce high yields and the well locations are linearly deployed along the axial part.

[0003] In well test interpretation technology, it is difficult to accurately characterize the distribution model that matches the relationship between natural fractures and matrix reservoirs, and its applicability is also poor. For analytical well test interpretation models of fractured reservoirs, homogeneity is often considered, that is, the fracture morphology is consistent and the fractures are evenly distributed within the basic reservoir.

[0004] Currently, the dual-porosity (pore and fracture) media models established based on this concept mainly include quasi-steady-state models, spherical models, and plate-like models. However, for deep gas reservoirs in the Kelasu tectonic belt of the Tarim Basin and the lower combination of the southern margin of the Junggar Basin, which have poor matrix properties, fractures as the main conduction system, and strong heterogeneity in fracture development, conventional well test interpretation models that assume uniform distribution of fractures within the matrix reservoir are not applicable. They can only perform equivalent parameter output, and the interpreted parameters cannot reflect the actual reservoir conditions. Summary of the Invention

[0005] This invention provides a method and related equipment for calculating the length of large-scale natural fractures, which solves the problem that conventional well test interpretation models can only output equivalent parameters and the interpretation parameters cannot reflect the actual reservoir.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for calculating the length of large-scale natural cracks includes:

[0008] A physical model of a natural fractured reservoir is established, and dimensionless variables of the physical model are defined. Based on the physical model and dimensionless variables, model constraints are obtained, and a mathematical model for well testing of the natural fractured reservoir is established according to the model constraints.

[0009] The dimensionless bottom hole pressure in the pull space, considering the well reservoir and skin effect, is obtained based on the mathematical model of well testing of natural fractured reservoir. The real-time space bottom hole pressure is obtained by inverting the dimensionless bottom hole pressure in the pull space, considering the well reservoir and skin effect.

[0010] Plot well test interpretation curves for naturally fractured reservoirs;

[0011] The theoretical bottom-hole pressure is obtained from the real-time space bottom-hole pressure and the well test interpretation curve of the natural fractured reservoir, and the theoretical well test curve is plotted.

[0012] The natural fracture length is obtained by fitting the theoretical well test curve with the actual well test curve.

[0013] A further improvement of this invention lies in establishing a physical model of a naturally fractured reservoir, defining dimensionless variables of the physical model, obtaining model constraints based on the physical model and dimensionless variables, and establishing a mathematical model for well testing of the naturally fractured reservoir based on the model constraints. The specific steps are as follows:

[0014] Establish a physical model for naturally fractured reservoirs;

[0015] Define dimensionless variables for the physical model of natural fractured reservoirs;

[0016] Based on the physical model of natural fracture reservoirs and the defined dimensionless variables, the internal control equations of natural fractures, the closure conditions at the fracture ends, the line source function in circular closed reservoirs, the pressure response at dimensionless coordinates, and the condition for the equality of fluid inflow and outflow mass in fractures are obtained in Lagrange space.

[0017] A mathematical model for well testing of natural fracture reservoirs is established based on the internal control equations of natural fractures in the Lagrange space, the sealing conditions at the fracture ends, the source function in a circular sealed reservoir, the pressure response at dimensionless coordinates, and the condition that the inflow and outflow masses of fluids in the fractures are equal.

[0018] A further improvement of this invention lies in the following steps: First, the dimensionless bottom-hole pressure in the pull-shaped space, considering both the reservoir and skin effect, is obtained based on a mathematical model of well testing in a natural fractured reservoir. The specific steps for inverting this dimensionless bottom-hole pressure in the pull-shaped space to obtain the real-time bottom-hole pressure are as follows:

[0019] The dimensionless bottom hole pressure in the pull-space is obtained based on the mathematical model of reservoir well testing.

[0020] The dimensionless bottom-hole pressure in the pull-space is obtained by considering the well reservoir and skin effect.

[0021] The real-time spatial bottom hole pressure is obtained by inverting the dimensionless bottom hole pressure in the Ra-shaped space after considering the well reservoir and skin effect.

[0022] A further improvement of this invention is that the dimensionless bottom-hole pressure in the pull-type space is:

[0023]

[0024] For dimensionless bottom hole pressure in pull-type space, For the first i The endpoints have dimensionless x-coordinates. For the first i +1 dimensionless x-coordinates at the endpoints For the first i Dimensionless flow of a point-based pull space The coordinates of the line source location are dimensionless. Let be the dimensionless ordinates of the two ends of the natural crack. As an intermediate variable, The dimensionless boundary distance, For dimensionless time-corresponding Lagrange space variables, Let I0 be the dimensionless wellbore radius, and let I0 and K0 be the zeroth-order imaginary argument Bessel functions of the first and second kind, respectively; I1 and K1 be the first-order imaginary argument Bessel functions of the first and second kind, respectively. For summation indicators.

[0025] A further improvement of this invention lies in the specific steps of plotting the well test interpretation curves for naturally fractured reservoirs as follows:

[0026] For oil and water wells, obtain pressure measurement data during the actual well production stage or shut-in stage, and plot well test interpretation curves.

[0027] For gas wells, first convert the actual well production stage or shut-in stage pressure measurement data into simulated pressure, and then draw the well test interpretation curve based on the simulated pressure.

[0028] The simulated pressure is:

[0029]

[0030] 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.

[0031] A further improvement of this invention lies in obtaining the theoretical bottom-hole pressure based on the real-time spatial bottom-hole pressure and the well test interpretation curve of the natural fractured reservoir, specifically as follows:

[0032]

[0033]

[0034] For the original pressure, The theoretical bottom hole pressure, For integration variables Output per moment Production pressure differential per unit output At the current time t With integral variables The first derivative of the time difference, Production pressure differential per unit output t For time, This represents the real-time bottom-of-well pressure. For penetration rate, For effective thickness, It is dimensionless time.

[0035] A system for calculating the length of large-scale natural cracks includes:

[0036] Modeling module: Used to establish a physical model of a natural fractured reservoir, define the dimensionless variables of the physical model of the natural fractured reservoir, obtain model constraints based on the physical model of the natural fractured reservoir and the dimensionless variables, and establish a mathematical model of well testing of the natural fractured reservoir according to the model constraints.

[0037] Calculation module: used to obtain the dimensionless bottom hole pressure in the pull space after considering the well reservoir and skin effect based on the mathematical model of well testing of natural fractured reservoir, and to invert the dimensionless bottom hole pressure in the pull space after considering the well reservoir and skin effect to obtain the real-time space bottom hole pressure;

[0038] First curve plotting module: used to plot well test interpretation curves for natural fractured reservoirs;

[0039] The second curve plotting module is used to obtain the theoretical bottom-hole pressure based on the real-time spatial bottom-hole pressure and the well test interpretation curve of the natural fractured reservoir, and to plot the theoretical well test curve.

[0040] Fitting module: Used to fit the theoretical well test curve with the measured curve to obtain the natural fracture length.

[0041] 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 length of a large-scale natural crack.

[0042] 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 length of a large-scale natural crack.

[0043] A computer program product includes a computer program that, when executed by a processor, implements the steps of the method for calculating the length of a large-scale natural crack.

[0044] Compared with existing technologies, the present invention has the following beneficial effects: The present invention provides a method for calculating the length of natural fractures on a large scale. By establishing a mathematical model of a natural fracture reservoir well test, calculating the real-time bottom hole pressure, plotting the interpretation curve of the natural fracture reservoir well test, and then combining the real-time bottom hole pressure with the interpretation curve to obtain the theoretical bottom hole pressure and plot the theoretical well test curve, the natural fracture length is finally obtained by fitting the theoretical and measured curves. This method breaks through the limitation of uniform fracture distribution in conventional models, is suitable for deep gas reservoirs with poor matrix properties and strong fracture heterogeneity, avoids the problem of only being able to obtain equivalent parameters and the interpretation parameters not reflecting the actual situation, accurately characterizes the fracture development state, and improves the accuracy of well test interpretation.

[0045] Furthermore, by establishing an analytical well test model and performing well test curve fitting, the development length of a large-scale natural fracture around the well can be accurately determined, providing strong support for the characterization of favorable zones within the trap and the deployment of drilling in adjacent wells within the same trap, thereby improving the success rate of trap exploration and evaluation and the speed of oil and gas production. Attached Figure Description

[0046] Figure 1 This is a flowchart of a method for calculating the length of large-scale natural cracks according to the present invention;

[0047] Figure 2 This is a schematic diagram of a physical model of a natural fractured reservoir according to an embodiment of the present invention, wherein... x 1, x 2 represents the x-coordinate of the two ends of the natural crack. w The width of the natural crack. represents the dimensionless ordinates of the two ends of the natural crack;

[0048] Figure 3 This is a graph showing the well test curve fitting results of an example well in an embodiment of the present invention, wherein... For the duration of unstable well testing, This is a simulated pressure difference;

[0049] Figure 4 This is a block diagram of a large-scale natural crack length calculation system according to the present invention. Detailed Implementation

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] like Figure 1 As shown, this invention provides a method for calculating the length of large-scale natural cracks, including:

[0055] S1: Establish a physical model of a natural fractured reservoir, define dimensionless variables of the physical model of the natural fractured reservoir, obtain model constraints based on the physical model of the natural fractured reservoir and the dimensionless variables, and establish a mathematical model of well testing of the natural fractured reservoir according to the model constraints.

[0056] S2: Based on the mathematical model of well testing of natural fractured reservoir, the dimensionless bottom hole pressure in the pull space after considering the well reservoir and skin effect is obtained. The real-time space bottom hole pressure is obtained by inverting the dimensionless bottom hole pressure in the pull space after considering the well reservoir and skin effect.

[0057] S3: Plot well test interpretation curves for naturally fractured reservoirs;

[0058] S4: Obtain the theoretical bottom-hole pressure based on the real-time space bottom-hole pressure and the well test interpretation curve of the natural fractured reservoir, and plot the theoretical well test curve;

[0059] S5: Fit the theoretical well test curve with the measured curve to obtain the natural fracture length.

[0060] By establishing a mathematical model for well testing of naturally fractured reservoirs, calculating real-time bottom hole pressure, and plotting interpretation curves for well testing of naturally fractured reservoirs, and then combining the real-time bottom hole pressure with the interpretation curves to obtain the theoretical bottom hole pressure and plot the theoretical well test curves, the natural fracture length is finally obtained by fitting the theoretical and measured curves. This approach overcomes the limitations of conventional models where fractures are uniformly distributed, is suitable for deep gas reservoirs with poor matrix properties and strong fracture heterogeneity, avoids the problem of only being able to obtain equivalent parameters and interpreting parameters that do not reflect reality, accurately characterizes the fracture development state, and improves the accuracy of well test interpretation.

[0061] The detailed steps are as follows:

[0062] A physical model of a naturally fractured reservoir is established, and dimensionless variables of the physical model are defined. Based on the physical model and the dimensionless variables, model constraints are obtained. A mathematical model for well testing of the naturally fractured reservoir is then established based on these constraints.

[0063] (1) Establish a physical model of natural fracture reservoirs

[0064] Physical models of natural fractured reservoirs, such as Figure 2 As shown, the model assumes that the vertical well is located at the center of the circular reservoir, i.e., the origin of the coordinate system. O At this location, production is constant; the reservoir has an impermeable, sealed boundary; a large-scale natural fracture exists near the vertical well, extending along the direction of the natural fracture. x The axial direction and the direction perpendicular to the crack are: y Along the axial direction, the coordinates of the two ends of the crack are respectively ( x 1, b )and( x 2, b The crack width is w The fracture allows fluid to pass through and has a certain conductivity; the mass of fluid flowing into the fracture is equal to the mass of fluid flowing out; the fluid is single-phase and weakly compressible; the fluid obeys Darcy's law, and the effects of capillary force and gravity are ignored; the wellbore storage effect and skin effect are considered.

[0065] (2) Define a dimensionless variable

[0066] To simplify the mathematical model of natural fractured reservoirs, the relevant dimensionless variables are defined as follows:

[0067] , , , .

[0068] , , , , .

[0069] , , .

[0070] , , .

[0071] In the formula: The pressure is dimensionless and has no quantity. Pressure, unit is MPa; The original pressure is expressed in MPa. Permeability, in μm 2 ; Effective thickness, in meters (m); Production volume, in meters (m). 3 / d; The viscosity of the fluid is expressed in mPa·s. This is the volume index, in meters. 3 / m 3 ; It is dimensionless time; Time, in hours; Porosity, expressed as % The overall compressibility factor is expressed in MPa. -1 ; For reference length, the unit is meters; , () represents dimensionless coordinates at any position; , ( ) represents the coordinates of any position, in meters; , () represents the dimensionless coordinates of the line source location; , ( ) represents the coordinates of the line source location, in meters; , ( ) represents the dimensionless x-coordinates of the two endpoints of a natural crack; , () represents the x-coordinates of the two ends of the natural crack, in meters; It is a dimensionless conduction capacity, which is dimensionless. K F Permeability of natural fractures, in μm 2 ; w The width of the natural crack is expressed in meters (m). The conductivity of natural fractures, expressed in μm. 2 ·m; is the dimensionless wellbore storage coefficient, which is dimensionless; This is the wellbore storage coefficient, in meters. 3 / MPa; The crack element is dimensionless and has no dimension. is the length of the crack element, in meters; It is a dimensionless flow, without dimension. The difference in linear density flow rate of the cracks, in m³. 2 / d; The number of subdivision units for natural cracks; The length of a natural crack is measured in meters. The radius of the dimensionless wellbore is dimensionless. The radius of the wellbore is in meters (m).

[0072] (3) Establish a mathematical model for natural fracture reservoirs

[0073] The governing equation for the interior of natural fractures in the pull-type space is:

[0074] (1)

[0075] in For cracks in a tensile space without dimensional pressure, The dimensionless flow rate of the crack in the pull-type space.

[0076] The sealing condition at the end of the crack is:

[0077] (2)

[0078] (3)

[0079] The source function in a circular closed reservoir is:

[0080] (4)

[0081] in, As an intermediate variable, This refers to the dimensionless pressure of the reservoir.

[0082] in:

[0083] .

[0084] In the formula: u Dimensionless time Corresponding to Lagrange space variables, dimensionless; ω The energy storage ratio is dimensionless. λ I0 and K0 are the crosstalk coefficients, which are dimensionless; I0 and K0 are the first and second kind zero-order imaginary argument Bessel functions, respectively; I1 and K1 are the first and second kind first-order imaginary argument Bessel functions, respectively.

[0085] The pressure response at any location in the reservoir is the sum of the pressure responses caused by all elements in the natural fractures and the pressure responses caused by the wellbore. Therefore, combining the line source function (4), the dimensionless coordinates ( , The pressure response at point ) is:

[0086] (5)

[0087] in, For the first iThe endpoints have dimensionless x-coordinates. For the first i +1 dimensionless x-coordinates at the endpoints For the first i Dimensionless flow of a point-based pull space Let be the dimensionless ordinates of the two ends of the natural crack. As an intermediate variable, The dimensionless boundary distance, For summation indicators.

[0088] The condition that the mass of fluid flowing into the crack is equal to the mass of fluid flowing out is as follows:

[0089] (6)

[0090] A mathematical model for well testing of natural fracture reservoirs is established based on the internal control equations of natural fractures in the Lagrange space, the sealing conditions at the fracture ends, the source function in a circular sealed reservoir, the pressure response at dimensionless coordinates, and the condition that the inflow and outflow masses of fluids in the fractures are equal.

[0091] Based on the mathematical model of well testing in a natural fractured reservoir, the dimensionless bottom-hole pressure in the pull-space configuration, considering both the reservoir and skin effects, is obtained. The real-time bottom-hole pressure in the pull-space configuration, considering both the reservoir and skin effects, is then inverted to obtain the following:

[0092] Taking a double integral of equation (1) yields:

[0093] (7)

[0094] Combining equations (2) and (3), and writing the integral of equation (7) in discrete form, we can obtain:

[0095] (8)

[0096] In the formula: subscript i The index is the endpoint number of the crack element; subscript j The index of the midpoint of the crack element. The unit length is dimensionless.

[0097] Substituting equation (5) into equation (8), and rearranging the terms so that the right-hand side of the equation is a constant term, we get:

[0098] (9)

[0099] For the first i The endpoints have dimensionless x-coordinates. For the first i +1 dimensionless x-coordinates at endpoints.

[0100] In equation (9) j The value ranges from 1 to n Therefore, there are a total of n There are 10 equations. Combining these with the mass conservation condition (6), there are a total of 10 equations. n +1 equation, corresponding to n +1 unknown, that is n The dimensionless flow rates under +1 pull space are respectively: Dimensionless pressure in the crack under tension space Therefore, targeting n +1 equation n +1 unknown, solved using matrix methods. and .

[0101] Combining the line source function (4) again, the pressure response at the bottom of the well is the sum of the pressure responses caused by all elements in the natural fracture and the pressure responses caused by the wellbore, expressed as:

[0102] (10)

[0103] The dimensionless bottom hole pressure in the pull-down space is not considered in the context of well storage and skin effect.

[0104] The results already obtained Substituting into equation (10), the dimensionless bottom hole pressure in the pull space can be obtained.

[0105] Considering the well reservoir and skin effect, the dimensionless bottom hole pressure in the pull-out space is:

[0106] (11)

[0107] In the formula: S It is an epidermal factor, dimensionless. To account for the well reservoir and skin effect, the dimensionless bottom hole pressure in the pull-out space is calculated.

[0108] The real-time spatial bottom hole pressure solution can be obtained by performing Stehfest numerical inversion on equation (11) of the dimensionless bottom hole pressure solution in the pull-out space after considering the well reservoir and skin effect. .

[0109] Plot well test interpretation curves for naturally fractured reservoirs. Obtain the theoretical bottom-hole pressure based on real-time bottom-hole pressure and the well test interpretation curves for naturally fractured reservoirs. Plot theoretical well test curves. Fit the theoretical well test curves to the measured curves to obtain the natural fracture length. Specifically:

[0110] Using pressure measurement data from the actual well production or shut-in phases, well test interpretation curves are plotted. For gas wells, the actual well production or shut-in phase pressure measurement data must first be converted into pseudo-pressures, and then the well test interpretation curves are plotted based on the pseudo-pressures. The pseudo-pressures are:

[0111] (12)

[0112] 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.

[0113] According to the superposition principle, we have:

[0114] (13)

[0115] For integration variables, for The derivative of t For time, For integration variables Output per moment Production pressure differential per unit output At the current time t With integral variables The first derivative of the time difference.

[0116] in:

[0117]

[0118] in This refers to the production pressure differential per unit output.

[0119] The calculated real-time space bottom-hole pressure solution Substituting into equation (13) yields the theoretical bottom hole pressure at the corresponding pressure measurement time. And plot the theoretical well test curves.

[0120] The conductivity, half-length, and permeability of the natural fractures were repeatedly adjusted until the theoretical well test curves and the actual well test curves coincided, thus obtaining the correct parameters and finally the length of the natural fractures.

[0121] Another embodiment of the present invention provides a method for calculating the length of large-scale natural cracks, including:

[0122] Table 1 contains a collection of basic parameters for wellbore, fluid, and reservoir data from wells that have undergone unsteady gauging tests.

[0123] Table 1 Basic Data Table

[0124]

[0125] A mathematical model for well testing of naturally fractured reservoirs is established. Based on the pressure measurement data during the actual well production or shut-in stage, the simulated pressure data of the actual well test is obtained after transformation by equation (12). In the figure, Δ t This indicates the duration of the unstable well test, in hours (h). To simulate the pressure difference, well test interpretation curves were plotted using simulated pressure data from the actual well shut-in stage. Theoretical well test curves were plotted based on real-time bottom-hole pressure obtained from a mathematical model of natural fractured reservoir well testing. The theoretical and measured well test curves were then fitted together for interpretation. The fitting results are shown below. Figure 3 As can be seen from the figure, the theoretical and measured curves basically coincide, and the length of the natural crack is obtained as 920m through fitting.

[0126] like Figure 4 As shown, the present invention also provides a system for calculating the length of large-scale natural cracks, comprising:

[0127] Modeling module: Used to establish a physical model of a natural fractured reservoir, define the dimensionless variables of the physical model of the natural fractured reservoir, obtain model constraints based on the physical model of the natural fractured reservoir and the dimensionless variables, and establish a mathematical model of well testing of the natural fractured reservoir according to the model constraints.

[0128] Calculation module: used to obtain the dimensionless bottom hole pressure in the pull space after considering the well reservoir and skin effect based on the mathematical model of well testing of natural fractured reservoir, and to invert the dimensionless bottom hole pressure in the pull space after considering the well reservoir and skin effect to obtain the real-time space bottom hole pressure;

[0129] First curve plotting module: used to plot well test interpretation curves for natural fractured reservoirs;

[0130] The second curve plotting module is used to obtain the theoretical bottom-hole pressure based on the real-time spatial bottom-hole pressure and the well test interpretation curve of the natural fractured reservoir, and to plot the theoretical well test curve.

[0131] Fitting module: Used to fit the theoretical well test curve with the measured curve to obtain the natural fracture length.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] This invention also utilizes a computer program to instruct related hardware. When executed by a processor, this computer program can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or some intermediate form.

[0139] Another embodiment of the present invention provides a readable storage medium for storing a computer program. The computer-readable medium may include any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, 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 a jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium may not include electrical carrier signals and telecommunication signals.

[0140] 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 length of large-scale natural fractures, characterized by, The method comprises the following steps: establishing a natural fracture reservoir physical model, defining dimensionless variables of the natural fracture reservoir physical model, obtaining model constraint conditions based on the natural fracture reservoir physical model and the dimensionless variables, and establishing a natural fracture reservoir well testing mathematical model according to the model constraint conditions; obtaining dimensionless bottom hole pressure in a pull-type space considering well storage and skin effect based on the natural fracture reservoir well testing mathematical model, and inversely obtaining real-time spatial bottom hole pressure based on the dimensionless bottom hole pressure in the pull-type space considering well storage and skin effect; drawing a well testing interpretation curve of the natural fracture reservoir; obtaining theoretical bottom hole pressure based on the real-time spatial bottom hole pressure and the well testing interpretation curve of the natural fracture reservoir, and drawing a theoretical well testing curve; fitting the theoretical well testing curve and the actual well testing curve to obtain a natural fracture length; the step of obtaining dimensionless bottom hole pressure in a pull-type space considering well storage and skin effect based on the natural fracture reservoir well testing mathematical model, and inversely obtaining real-time spatial bottom hole pressure based on the dimensionless bottom hole pressure in the pull-type space considering well storage and skin effect, specifically comprises the following steps: obtaining dimensionless bottom hole pressure in a pull-type space based on a reservoir well testing mathematical model; obtaining dimensionless bottom hole pressure in a pull-type space considering well storage and skin effect based on the dimensionless bottom hole pressure in the pull-type space; inversely obtaining real-time spatial bottom hole pressure based on the dimensionless bottom hole pressure in the pull-type space considering well storage and skin effect; the dimensionless bottom hole pressure in the pull-type space is: B is the dimensionless bottomhole pressure in the Lagrangian space, B is the dimensionless bottomhole pressure in the Lagrangian space, i B is the dimensionless bottomhole pressure in the Lagrangian space, B is the dimensionless bottomhole pressure in the Lagrangian space, i B is the dimensionless bottomhole pressure in the Lagrangian space, B is the dimensionless bottomhole pressure in the Lagrangian space, i B is the dimensionless bottomhole pressure in the Lagrangian space, B is the dimensionless bottomhole pressure in the Lagrangian space, B is the dimensionless bottomhole pressure in the Lagrangian space, B is the dimensionless bottomhole pressure in the Lagrangian space, B is the dimensionless bottomhole pressure in the Lagrangian space, B is the dimensionless bottomhole pressure in the Lagrangian space, B is the dimensionless bottomhole pressure in the Lagrangian space, B is the dimensionless bottomhole pressure in the Lagrangian space, the step of obtaining theoretical bottom hole pressure based on the real-time spatial bottom hole pressure and the well testing interpretation curve of the natural fracture reservoir, specifically comprises the following steps: Poi is the initial pressure, Pth is the theoretical bottom hole pressure, t is the integration variable, t is the integration variable Qoi is the initial production rate, Dp is the drawdown pressure per unit of production at the current time t and the integration variable the first derivative of the time difference, Dp is the drawdown pressure per unit of production, t t is the time, Poi is the real time spatial bottom hole pressure, k is the permeability, h is the effective thickness, t is the dimensionless time.

2. The method of claim 1, wherein, establishing a natural fracture reservoir physical model; defining dimensionless variables of the natural fracture reservoir physical model; obtaining internal control equations of natural fractures in a pull-type space, end sealing conditions of the fractures, line source functions in a circular sealed reservoir, pressure responses at dimensionless coordinates, and equal conditions of fluid inflow mass and outflow mass in the fractures based on the natural fracture reservoir physical model and the defined dimensionless variables; establishing a natural fracture reservoir well testing mathematical model based on the internal control equations of natural fractures in a pull-type space, the end sealing conditions of the fractures, the line source functions in a circular sealed reservoir, the pressure responses at dimensionless coordinates, and the equal conditions of fluid inflow mass and outflow mass in the fractures. the step of drawing a well testing interpretation curve of the natural fracture reservoir, specifically comprises the following steps:

3. The method of claim 1, wherein the method further comprises: for an oil-water well, obtaining pressure measurement data in an actual well production stage or a shut-in stage, and drawing a well testing interpretation curve; for a gas well, first converting the pressure measurement data in the actual well production stage or the shut-in stage into pseudo-pressure, and then drawing a well testing interpretation curve based on the pseudo-pressure; the pseudo-pressure is: the large-scale natural fracture length calculation method according to any one of claims 1-3, comprising: wherein: P is atmospheric pressure, P0 is the original pressure, C0 is the deviation factor at original conditions, μ0 is the fluid viscosity at original conditions, P is the pseudo pressure, P is the pressure, P is the pressure p corresponding viscosity, P is the pressure p corresponding deviation factor.

4. A large-scale natural fracture length calculation system characterized by, ​ The modeling module is configured to establish a natural fracture reservoir physical model, define a dimensionless variable of the natural fracture reservoir physical model, obtain a model constraint condition based on the natural fracture reservoir physical model and the dimensionless variable, and establish a natural fracture reservoir well testing mathematical model according to the model constraint condition. The calculation module is configured to obtain a dimensionless bottom hole pressure in a pull type space considering well storage and skin effect according to the natural fracture reservoir well testing mathematical model, and obtain a real-time spatial bottom hole pressure by inverting the dimensionless bottom hole pressure in the pull type space considering well storage and skin effect. The first curve drawing module is configured to draw a well testing interpretation curve of the natural fracture reservoir. The second curve drawing module is configured to obtain a theoretical bottom hole pressure according to the real-time spatial bottom hole pressure and the well testing interpretation curve of the natural fracture reservoir, and draw a theoretical well testing curve. The fitting module is configured to fit the theoretical well testing curve with a measured curve to obtain a natural fracture length.

5. A computer device comprising a memory, a processor, and a computer program stored on the memory, wherein the computer program comprises instructions that, when executed by the processor, cause the processor to perform the method of any one of claims 1-4. The processor executes the computer program to implement the steps of the large-scale natural fracture length calculation method in any one of claims 1-3.

6. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the steps of the large-scale natural fracture length calculation method in any one of claims 1-3.

7. A computer program product comprising a computer program, characterized in that, The computer program is executed by the processor to implement the steps of the large-scale natural fracture length calculation method in any one of claims 1-3.

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