Crack density determination method and device, electronic equipment and storage medium

Abstract

The invention provides a fracture density determination method and device, electronic equipment and a storage medium, and relates to the technical field of geological exploration. The method comprises the steps that when it is determined that a crack inclination angle in a target area meets a preset crack inclination angle condition, a first calculation mode of an azimuth seismic reflection coefficient corresponding to the target area is acquired; the first calculation mode is a calculation mode of orientation seismic reflection coefficients under a horizontal transverse isotropic medium; modifying the first calculation mode based on a mapping relation between at least one calculation parameter included in the first calculation mode and the fracture density parameter to obtain a second calculation mode of the azimuth seismic reflection coefficient; and determining a third calculation mode corresponding to the azimuth elastic impedance based on the second calculation mode and the mapping relation between the azimuth elastic impedance and the azimuth seismic reflection coefficient, and determining the fracture density in the target area based on the Fourier series corresponding to the third calculation mode, thereby improving the accuracy of fracture density prediction.

Description

Technical Field

[0001] The present application relates to the field of geological exploration technology, and in particular to a method, device, electronic equipment and storage medium for determining fracture density. Background Art

[0002] With the increasing complexity of exploration targets and the increasing demand for exploration, fractured gas-bearing reservoirs have become an important target for oil and gas exploration. In fractured gas-bearing reservoirs, fractures, as storage spaces and seepage channels, are important factors affecting the rock properties of gas-bearing reservoirs. Therefore, the fracture density of fractured gas-bearing reservoirs can be used to more accurately determine the location of gas-bearing reservoirs.

[0003] Since the kinematic and dynamic parameters of seismic waves usually show azimuthal anisotropy when propagating in fractured formations, related technologies often use the azimuthal anisotropy law of seismic data to predict the fracture density of fractured gas-bearing reservoirs. For example, the degree of development of fractures in fractured formations is indirectly indicated by fracture weakness parameters (such as normal weakness or tangential weakness) and anisotropy parameters, that is, the fracture density of fractured formations is indirectly predicted.

[0004] However, when using the above-mentioned fracture density prediction method to predict fracture density in formations with high-angle fractures or vertical fractures, the fracture weakness parameters and anisotropy parameters cannot directly describe the fracture characteristics in formations with high-angle fractures or vertical fractures and are uncertain, resulting in low accuracy in fracture density prediction. Summary of the invention

[0005] The embodiments of the present application provide a method, device, electronic device and storage medium for determining fracture density, which are used to improve the accuracy of fracture density prediction when predicting fracture density of formations with high-angle fractures or vertical fractures.

[0006] In a first aspect, an embodiment of the present application provides a method for determining crack density, the method comprising: Obtaining the fracture dip in the target area, and when determining that the fracture dip meets the preset fracture dip condition, obtaining a first calculation method of the azimuthal seismic reflection coefficient corresponding to the target area; the first calculation method is a calculation method of the azimuthal seismic reflection coefficient in a horizontal transversely isotropic (HTI) medium; Based on the mapping relationship between at least one calculation parameter included in the first calculation method and the fracture density parameter, the first calculation method is modified to obtain a second calculation method of the azimuthal seismic reflection coefficient; Based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, a third calculation method corresponding to the azimuthal elastic impedance is determined, and the fracture density in the target area is determined based on the Fourier series corresponding to the third calculation method.

[0007] In an optional embodiment, the at least one calculated parameter includes: a normal weakness parameter and a tangential weakness parameter; Based on the mapping relationship between at least one calculation parameter included in the first calculation method and the crack density parameter, the first calculation method is modified, including: Based on the ratio between the shear wave modulus and the longitudinal wave modulus in the target area and the crack density parameter, the mapping relationship between the normal weakness parameter and the tangential weakness parameter and the crack density parameter is constructed; The first calculation method is modified based on the two constructed mapping relationships.

[0008] In an optional embodiment, based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, a third calculation method corresponding to the azimuthal elastic impedance is determined, including: Based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, a fourth calculation method corresponding to the azimuthal elastic impedance is obtained; The fourth calculation method is integrated and indexed to obtain the third calculation method.

[0009] In an optional embodiment, determining the crack density in the target area based on the Fourier series corresponding to the third calculation method includes: Performing logarithm processing on the third calculation method to obtain the third calculation method after logarithm processing, and performing Fourier series expansion processing on the third calculation method after logarithm processing to obtain a Fourier series; Based on the multiple harmonic components included in the Fourier series, the crack density is determined.

[0010] In an optional embodiment, the crack density is determined based on a plurality of harmonic components included in the Fourier series, including: From the plurality of harmonic components, obtaining a second harmonic component corresponding to the second harmonic; Determine the Fourier coefficient corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component; The fracture density is determined based on the Fourier coefficients and the first portion of the Fourier coefficients excluding the fracture density parameter.

[0011] In an optional embodiment, determining the Fourier coefficient corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component includes: Based on the sine component and the cosine component, the orientation of the crack symmetry axis set for the target area is determined; The sign of the Fourier coefficient is determined based on the sine component and the orientation of the crack symmetry axis, and the magnitude of the Fourier coefficient is determined based on the sine component and the cosine component.

[0012] In an optional embodiment, before determining the Fourier coefficient corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component, the method further includes: Obtaining the incident angle and the first angle of the target area; the first angle is the angle between the observation azimuth of the target area and the azimuth of the crack symmetry axis; Obtaining a sine component based on the incident angle, the first angle, and a cosine integral result of the first angle included in the third calculation method; And, based on the incident angle, the first angle, and the sine integration result of the first angle included in the third calculation method, a cosine component is obtained.

[0013] In a second aspect, an embodiment of the present application further provides a device for determining crack density, the device comprising: An acquisition module, used to acquire the fracture dip in the target area, and when it is determined that the fracture dip meets the preset fracture dip condition, acquire a first calculation method of the azimuth seismic reflection coefficient corresponding to the target area; the first calculation method is a calculation method of the azimuth seismic reflection coefficient under the HTI medium; A modification module, configured to modify the first calculation method based on a mapping relationship between at least one calculation parameter included in the first calculation method and a fracture density parameter, to obtain a second calculation method of the azimuthal seismic reflection coefficient; A determination module is used to determine a third calculation method corresponding to the azimuthal elastic impedance based on the second calculation method and a mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, and to determine the fracture density in the target area based on the Fourier series corresponding to the third calculation method.

[0014] In an optional embodiment, the at least one calculated parameter includes: a normal weakness parameter and a tangential weakness parameter; When modifying the first calculation method based on the mapping relationship between at least one calculation parameter included in the first calculation method and the fracture density parameter, the modification module is specifically used to: Based on the ratio between the shear wave modulus and the longitudinal wave modulus in the target area and the crack density parameter, the mapping relationship between the normal weakness parameter and the tangential weakness parameter and the crack density parameter is constructed; The first calculation method is modified based on the two constructed mapping relationships.

[0015] In an optional embodiment, when determining the third calculation method corresponding to the azimuthal elastic impedance based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, the determination module is specifically used to: Based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, a fourth calculation method corresponding to the azimuthal elastic impedance is obtained; The fourth calculation method is integrated and indexed to obtain the third calculation method.

[0016] In an optional embodiment, when determining the crack density in the target area based on the Fourier series corresponding to the third calculation method, the determination module is specifically used to: Performing logarithm processing on the third calculation method to obtain the third calculation method after logarithm processing, and performing Fourier series expansion processing on the third calculation method after logarithm processing to obtain a Fourier series; Based on the multiple harmonic components included in the Fourier series, the crack density is determined.

[0017] In an optional embodiment, when determining the crack density based on a plurality of harmonic components included in the Fourier series, the determination module is specifically configured to: From the plurality of harmonic components, obtaining a second harmonic component corresponding to the second harmonic; Determine the Fourier coefficient corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component; The fracture density is determined based on the Fourier coefficients and the first portion of the Fourier coefficients excluding the fracture density parameter.

[0018] In an optional embodiment, when determining the Fourier coefficient corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component, the determination module is specifically used to: Based on the sine component and the cosine component, the orientation of the crack symmetry axis set for the target area is determined; The sign of the Fourier coefficient is determined based on the sine component and the orientation of the crack symmetry axis, and the magnitude of the Fourier coefficient is determined based on the sine component and the cosine component.

[0019] In an optional embodiment, before determining the Fourier coefficient corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component, the determination module is further configured to: Obtaining the incident angle and the first angle of the target area; the first angle is the angle between the observation azimuth of the target area and the azimuth of the crack symmetry axis; Obtaining a sine component based on the incident angle, the first angle, and a cosine integral result of the first angle included in the third calculation method; And, based on the incident angle, the first angle, and the sine integration result of the first angle included in the third calculation method, a cosine component is obtained.

[0020] In a third aspect, an embodiment of the present application further provides an electronic device, including: Processor; and Memory for storing programs, The program includes instructions, and when the instructions are executed by the processor, the processor executes the method for determining the crack density as described in the first aspect.

[0021] In a fourth aspect, an embodiment of the present application further provides a non-transitory computer-readable storage medium storing computer instructions, wherein the computer instructions are used to enable a computer to execute the method for determining the fracture density as described in the first aspect.

[0022] In a fifth aspect, the present application provides a computer program product, which, when called by a computer, enables the computer to execute the steps of the method for determining the fracture density as described in the first aspect.

[0023] The beneficial effects of this application are as follows: In the method for determining the fracture density provided in the embodiment of the present application, when it is determined that the fracture dip in the target area meets the estimated fracture dip condition, the calculation method of the azimuthal seismic reflection coefficient under the HTI medium, that is, the first calculation method, can be used as the first calculation method of the azimuthal seismic reflection coefficient corresponding to the target area. Then, based on the mapping relationship between at least one calculation parameter included in the first calculation method and the fracture density parameter, the first calculation method is modified to obtain the second calculation method of the azimuthal seismic reflection coefficient. Finally, based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, the third calculation method corresponding to the azimuthal elastic impedance is determined, and the fracture density in the target area is determined based on the Fourier series corresponding to the third calculation method. In this way, since the calculation method of the azimuthal seismic reflection coefficient under the HTI medium and the fracture density parameter can directly describe the fracture characteristics of the target area (such as a formation with high-angle fractures or vertical fractures), there is no need to indirectly indicate the fracture characteristics in the formation with high-angle fractures or vertical fractures through fracture weakness parameters and anisotropy parameters, thereby improving the accuracy of fracture density prediction.

[0024] In addition, other features and advantages of the present application will be described in the subsequent description, and partly become apparent from the description, or be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described here are used to provide a further understanding of the present application, constitute a part of the present application, and do not constitute an improper limitation on the present application. In the drawings: Figure 1 A schematic diagram of an optional system architecture applicable to the embodiments of the present application; Figure 2 A schematic diagram of an implementation flow of a method for determining crack density provided in an embodiment of the present application; Figure 3 A schematic diagram of the structure of a device for determining crack density provided in an embodiment of the present application; Figure 4 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be construed as being limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the drawings and embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.

[0027] It should be understood that the various steps described in the method implementation of the present application can be performed in different orders and / or performed in parallel. In addition, the method implementation may include additional steps and / or omit the steps shown. The scope of the present application is not limited in this respect.

[0028] The term "including" and its variations used in this document are open inclusions, that is, "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments". Relevant definitions of other terms will be given in the description below. It should be noted that the concepts of "first", "second", etc. mentioned in this application are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0029] It should be noted that the modifications of "one" and "plurality" mentioned in the present application are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0030] The names of the messages or information exchanged between multiple devices in the embodiments of the present application are only used for illustrative purposes and are not used to limit the scope of these messages or information.

[0031] Some of the terms used in the embodiments of the present application are explained below to facilitate understanding by those skilled in the art.

[0032] (1) Oil and gas reservoir: It is the basic unit of oil and gas accumulation and the object of oil and gas exploration. An oil and gas reservoir exists in an independent enclosure. If only oil accumulates in the enclosure, it is called a pure oil reservoir (or oil reservoir); if only natural gas accumulates in the enclosure, it is called a pure gas reservoir (or gas reservoir). Oil and gas have a certain distribution pattern and a unified pressure system in the enclosure.

[0033] (2) Azimuth seismic reflection coefficient: It is a parameter used in seismic exploration to estimate the characteristics of underground rocks, reflecting the ability of seismic waves to reflect in underground media. The calculation of azimuth seismic reflection coefficient is usually based on the ratio of the amplitude of the seismic wave to the amplitude of the incident wave, and this ratio is affected by the incident angle and the characteristics of the underground medium.

[0034] (3) Fracture symmetry axis: In seismic exploration and fracture medium parameter inversion, the symmetry axis is closely related to the distribution and orientation of fractures. In fractured gas reservoir exploration, the fracture symmetry axis is used to determine the orientation of fractures.

[0035] (4) Longitudinal wave modulus: also known as compression modulus, is a physical quantity that describes the material's ability to resist deformation when subjected to longitudinal compression or tension.

[0036] (5) Shear modulus: also known as shear modulus, describes the deformation characteristics of a material under shear stress.

[0037] (6) Normal weakness: refers to the ratio of the elastic modulus of the rock in the normal direction to the elastic modulus in the tangential direction. It reflects the strength and rigidity of the rock in the direction perpendicular to the fracture. The presence of fluid will change the porosity and pressure distribution of the formation, thereby affecting the elastic modulus of the formation. Therefore, normal weakness is very sensitive to the fluid distribution in fractured reservoirs.

[0038] (7) Tangential weakness: refers to the ratio of the elastic modulus of the rock in the tangential direction to the elastic modulus in the normal direction. It reflects the strength and rigidity of the rock in the direction parallel to the fracture. Since the flow of fluid in the fracture will change the tangential elastic modulus of the formation, the tangential weakness is also sensitive to the fluid distribution in the fractured reservoir.

[0039] (8) Azimuth elastic impedance: It is a parameter used in seismic exploration to estimate underground rock properties. It combines factors such as seismic wave velocity, formation pressure and temperature, and can reflect geological information such as the porosity and oil content of the formation. In seismic exploration, azimuth elastic impedance is usually used to indirectly reflect the porosity and oil content of the formation, which is of great significance for studying the fracture characteristics of the reservoir and identifying fluids.

[0040] Based on the above-mentioned nouns and related terminology explanations, the design concept of the embodiments of the present application is briefly introduced below: With the increasing complexity of exploration targets and the increasing demand for exploration, fractured gas-bearing reservoirs represented by carbonate rocks, tight sandstones, shales, etc. have become the focus of researchers. In such oil and gas reservoirs, fractures, as storage spaces and seepage channels, are important factors affecting the rock properties of gas-bearing reservoirs. Since the kinematic and dynamic parameters of seismic waves usually show azimuthal anisotropy when propagating in fractured formations, the detection of fractures using the azimuthal anisotropy law of seismic data has become the main means of fracture prediction.

[0041] For example, the degree of development of fractures in fractured formations is indirectly indicated by fracture weakness parameters (e.g., normal weakness or tangential weakness) and anisotropy parameters, that is, the fracture density of fractured formations is indirectly predicted. However, it is difficult to obtain an intuitive description of the fracture characteristics in formations with high-angle fractures or vertical fractures by using the aforementioned fracture density prediction method. In addition, due to the large number of parameters in the forward equation, the predicted fracture weakness parameters and anisotropy parameters have large uncertainties, resulting in low accuracy of the prediction results.

[0042] Specifically, most existing fracture density prediction methods indirectly indicate fracture density through ellipse fitting, or convert the predicted anisotropy parameters or fracture weakness parameters to obtain fracture density, which easily introduces cumulative errors during the conversion process. In addition, since anisotropy parameters and fracture weakness parameters contribute little to seismic data, the use of conventional seismic multi-parameter simultaneous inversion methods to solve inverse problems is highly ill-conditioned and has a lot of uncertainty. These problems make it difficult to quantitatively describe fracture density, which in turn affects the judgment of gas-bearing reservoirs with high-angle fractures or vertical fractures.

[0043] It can be seen that when predicting the fracture density of a stratum with high-angle fractures or vertical fractures, how to improve the accuracy of fracture density prediction is a problem that needs to be solved urgently. In view of this, in order to solve or improve the aforementioned problems, an embodiment of the present application provides a method for determining fracture density, which may specifically include: obtaining the fracture dip in the target area, and when determining that the fracture dip meets the preset fracture dip condition, obtaining a first calculation method of the azimuthal seismic reflection coefficient corresponding to the target area; the first calculation method is a calculation method of the azimuthal seismic reflection coefficient under the HTI medium; then, based on the mapping relationship between at least one calculation parameter included in the first calculation method and the fracture density parameter, the first calculation method is modified to obtain a second calculation method of the azimuthal seismic reflection coefficient; finally, based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, a third calculation method corresponding to the azimuthal elastic impedance is determined, and the fracture density in the target area is determined based on the Fourier series corresponding to the third calculation method.

[0044] Based on the above method, due to the influence of the underground tectonic stress field, the cracks in the stratum generally show the characteristics of having a certain main arrangement direction and vertical directional distribution. Therefore, under the assumption of seismic equivalent medium theory, the stratum with high-angle cracks or vertical cracks (i.e., the target area) can usually be equivalent to HTI medium. Therefore, the calculation method of the azimuthal seismic reflection coefficient under the HTI medium, i.e., the first calculation method, can be used as the first calculation method of the azimuthal seismic reflection coefficient corresponding to the target area. In this way, the calculation method of the azimuthal seismic reflection coefficient under the HTI medium and the fracture density parameter can directly describe the fracture characteristics of the target area, without indirectly indicating the fracture characteristics in the stratum with high-angle cracks or vertical cracks through the fracture weakness parameter and the anisotropy parameter, thereby improving the accuracy of fracture density prediction.

[0045] In particular, the preferred embodiments of the present application are described below in conjunction with the drawings in the specification. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application, and the embodiments of the present application and the features in the embodiments may be combined with each other if there is no conflict.

[0046] See also Figure 1As shown, it is a schematic diagram of an optional system architecture applicable to an embodiment of the present application, and the system architecture may include: two terminal devices 101 and a server 102. Each terminal device 101 and the server 102 can exchange information through a communication network, wherein the communication mode adopted by the communication network may include: wireless communication mode and wired communication mode. Exemplarily, the terminal device 101 can access the network through cellular mobile communication technology and communicate with the server 102. The cellular mobile communication technology, for example, includes the fifth generation mobile communication (5th generation mobile networks, 5G) technology or the next generation mobile communication technology.

[0047] Optionally, the terminal device 101 may access the network through a short-range wireless communication method to communicate with the server 102. The short-range wireless communication method, for example, includes wireless fidelity (Wi-Fi) technology.

[0048] The embodiment of the present application does not impose any restriction on the number of communication devices involved in the above system architecture. For example, the above system architecture may include more terminal devices, or fewer terminal devices, or other network devices. Figure 1 As shown, only two terminal devices 101 and a server 102 are used as an example for description, and the above-mentioned communication devices and their respective functions are briefly introduced below.

[0049] The terminal device 101 is a device that can provide voice and / or data connectivity to users, and can be a device that supports wired and / or wireless connection.

[0050] Exemplarily, the terminal device 101 may include, but is not limited to: a mobile phone, a tablet computer, a laptop computer, a PDA, a mobile internet device (MID), a wearable device, a virtual reality (VR) device, an augmented reality (AR) device, a wireless terminal device in industrial control, a wireless terminal device in unmanned driving, a wireless terminal device in a smart grid, a wireless terminal device in transportation safety, a wireless terminal device in a smart city, or a wireless terminal device in a smart home, etc.

[0051] In addition, the terminal device 101 may be installed with a relevant client, which may be software, such as an application (APP), a browser, a short video software, etc., or a web page, a small program, etc. It should be noted that the terminal device 101 in the embodiment of the present application may enable the above-mentioned client related to the determination of crack density to send a determination request for the crack density of the target area (or a prediction request for the crack density) to the server 102, so as to subsequently perform the method steps such as determination of the crack density of the target area.

[0052] Server 102 can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers. It can also be a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, content delivery networks (CDNs), and big data and artificial intelligence platforms.

[0053] It is worth mentioning that in the embodiment of the present application, the server 102 can be used to obtain the fracture dip in the target area, and when it is determined that the fracture dip meets the preset fracture dip condition, obtain the first calculation method of the azimuthal seismic reflection coefficient corresponding to the target area; then, based on the mapping relationship between at least one calculation parameter included in the first calculation method and the fracture density parameter, the first calculation method is modified to obtain the second calculation method of the azimuthal seismic reflection coefficient; finally, based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, the third calculation method corresponding to the azimuthal elastic impedance is determined, and the fracture density in the target area is determined based on the Fourier series corresponding to the third calculation method. Among them, the first calculation method is a calculation method of the azimuthal seismic reflection coefficient under the HTI medium.

[0054] The following describes the method for determining crack density provided by an exemplary embodiment of the present application in combination with the above-mentioned system architecture and with reference to the accompanying drawings. It should be noted that the above-mentioned system architecture is only shown to facilitate understanding of the spirit and principles of the present application, and the implementation of the present application is not limited in this regard.

[0055] See also Figure 2 As shown, it is a schematic diagram of an implementation process of a method for determining crack density provided in an embodiment of the present application. The execution subject takes a server as an example. The specific implementation process of the method is as follows: S201: Acquire a fracture dip in a target area, and when it is determined that the fracture dip satisfies a preset fracture dip condition, acquire a first calculation method of an azimuthal seismic reflection coefficient corresponding to the target area.

[0056] Among them, the above-mentioned preset crack inclination conditions can be the inclination range corresponding to high-angle cracks and / or vertical cracks, that is, the preset crack inclination conditions are: the inclination range corresponding to high-angle cracks, that is, [70°, 90°), or the inclination range corresponding to vertical cracks, that is, 90°, or the inclination range corresponding to high-angle cracks and vertical cracks, that is, [70°, 90°].

[0057] Therefore, when it is determined that the fracture inclination in the target area meets the above-mentioned preset fracture inclination conditions, it can be determined that the fracture in the target area is a high-angle fracture or a vertical fracture, and then the target area is equivalent to an HTI medium.

[0058] The first calculation method mentioned above is a calculation method for calculating the azimuth seismic reflection coefficient under the HTI medium. Optionally, the calculation method for calculating the azimuth seismic reflection coefficient under the HTI medium (ie, the first calculation method) can be specifically expressed as follows: (1) in, R pp ( θ , ) represents the azimuthal seismic reflection coefficient, θ represents the incident angle of the target area, Indicates the observation direction of the target area φ Azimuth of the crack φ sym The angle between them, namely the first angle, M and μ represents the longitudinal and transverse wave moduli in an isotropic background, ρ represents the density of the target area, δ N and δ T It represents the normal weakness parameter and tangential weakness parameter of the crack. The symbol “-” on the top of the model parameter represents the average value of the model parameters of the upper and lower layers of the target area. The symbol “Δ” represents the difference between the model parameters of the upper and lower layers of the target area. g = μ / M .

[0059] S202: Based on the mapping relationship between at least one calculation parameter included in the first calculation method and the fracture density parameter, the first calculation method is modified to obtain a second calculation method of the azimuthal seismic reflection coefficient.

[0060] Since some of the calculation parameters included in the first calculation method (i.e., at least one of the above-mentioned calculation parameters, such as the normal weakness parameter δ N and the tangential weakness parameter δ T) and the existence of a mapping relationship between the fracture density parameters. Therefore, the server can optimize the first calculation method into a calculation method carrying the fracture density parameters through the mapping relationship between the aforementioned partial calculation parameters and the fracture density parameters, thereby reducing the calculation parameters of the azimuth seismic reflection coefficient, thereby reducing the uncertainty of the calculation parameters, and further improving the accuracy of subsequent predictions of the fracture density.

[0061] Optionally, the at least one calculation parameter mentioned above may include: a normal weakness parameter and a tangential weakness parameter. Therefore, the mapping relationship between the at least one calculation parameter mentioned above and the fracture density parameter may include: a mapping relationship between the normal weakness parameter and the fracture density parameter (or referred to as a first mapping relationship), and a mapping relationship between the tangential weakness parameter and the fracture density parameter (or referred to as a second mapping relationship). Exemplarily, for a gas-bearing reservoir, the mapping relationship between the normal weakness parameter and the tangential weakness parameter of the fracture and the fracture density parameter can be simplified to the following linear relationship: (2) in, δ N represents the normal weakness parameter of the crack, δ T represents the tangential weakness parameter of the crack, e represents the crack density in the target area, g represents the shear wave modulus in an isotropic background μ and longitudinal wave modulus M The ratio between .

[0062] Therefore, when executing step S202, the server can construct a mapping relationship between the normal weakness parameter and the tangential weakness parameter and the fracture density parameter (i.e., the first mapping relationship and the second mapping relationship recorded in formula (2)) based on the ratio between the transverse wave modulus and the longitudinal wave modulus of the target area and the fracture density parameter, thereby modifying the above-mentioned first calculation method based on the two constructed mapping relationships to obtain the second calculation method of the azimuth seismic reflection coefficient. In this way, there is no need to indirectly indicate the fracture characteristics in the target area through the fracture weakness parameter, thereby improving the accuracy of fracture density prediction.

[0063] In other words, based on the second calculation method of the azimuthal seismic reflection coefficient, the first calculation method of the azimuthal seismic reflection coefficient recorded in the above formula (1), and combined with the first mapping relationship and the second mapping relationship recorded in the above formula (2), the azimuthal seismic reflection coefficient of the target area can be directly characterized by the fracture density parameter.

[0064] Exemplarily, the second calculation method of the azimuthal seismic reflection coefficient can be specifically expressed as follows: (3) in, (4) Based on the second calculation method described above (i.e., formula (3) and formula (4)), it can be seen that it only includes four parameters, which greatly reduces the uncertainty of multi-parameter inversion compared to the first calculation method; and, using the second calculation method described above, the anisotropy term is only related to the fracture density parameter, which reduces the cumulative error when calculating the fracture density parameter from the inverted fracture weakness parameter or anisotropy parameter, thereby improving the accuracy of fracture prediction.

[0065] S203: Based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, determine a third calculation method corresponding to the azimuthal elastic impedance, and determine the fracture density in the target area based on the Fourier series corresponding to the third calculation method.

[0066] Since the second calculation method is very susceptible to the influence of seismic wavelets and noise when performing seismic inversion, and it is difficult to determine the crack density parameters of the target area from the response results. In order to improve the above-mentioned problems, the characteristics of azimuthal elastic impedance can be combined to achieve the prediction of crack density in the target area. Therefore, based on the second calculation method and the mapping relationship between azimuthal elastic impedance and azimuthal seismic reflection coefficient, the third calculation method corresponding to azimuthal elastic impedance can be determined.

[0067] The mapping relationship between the above azimuthal elastic impedance and azimuthal seismic reflection coefficient can be specifically expressed as follows: (5) in, R pp ( θ , ) represents the azimuthal seismic reflection coefficient, Δ EI ( θ , ) represents the difference in azimuthal elastic impedance between the upper and lower media in the target area, It represents the average value of the azimuthal elastic impedance between the upper and lower media in the target area.

[0068] When the elastic parameters on both sides of the reflection interface of the target area are not much different, that is, The server may obtain a fourth calculation method corresponding to the azimuthal elastic impedance based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient. Optionally, the fourth calculation method may be specifically expressed as follows: (6) Next, the fourth calculation method is integrated and indexed to obtain a normalized calculation method of azimuthal elastic impedance, namely, a third calculation method. Optionally, the third calculation method can be specifically expressed as follows: (7) in, The reference value of the azimuthal elastic impedance corresponding to the target area can usually be obtained by averaging the logging curves of the target layer section, where the target layer section is a reservoir included in the deeply buried reservoir.

[0069] Further, after determining the third calculation method corresponding to the azimuthal elastic impedance, the server can predict or determine the crack density in the target area based on Fourier series analysis. In an optional implementation, in order to improve the efficiency of crack density prediction and reduce the computational complexity, the server can perform logarithmic processing on the third calculation method to obtain the third calculation method after logarithmic processing, and perform Fourier series expansion processing on the third calculation method after logarithmic processing to obtain the Fourier series, thereby determining the crack density based on multiple harmonic components included in the Fourier series.

[0070] The third calculation method after the logarithmic processing is also the linearized azimuthal elastic impedance expression. Exemplarily, the third calculation method after the logarithmic processing can be specifically expressed as follows: (8) in, (9) because = φ - φ sym , the third calculation method after the logarithmic processing is subjected to Fourier series expansion processing, and the Fourier series of the azimuthal elastic impedance obtained, taking the expansion into a 4-order Fourier series as an example, can be specifically expressed as follows: (10) in, (11) in, r 0 ( θ ) represents the zero-order component of the azimuthal elastic impedance, E ( θ ) represents the anisotropic term included in the zero-order component (i.e. E ( θ ) e ) except for the crack density parameter e The parameters outside of r 2 ( θ) represents the second-order component of azimuthal elastic impedance, F ( θ ) represents the second-order component except the crack density parameter e The parameters outside of r 4 ( θ ) represents the fourth-order component of azimuthal elastic impedance, G ( θ ) represents the fourth-order component except the crack density parameter e Parameters outside of the .

[0071] It is understandable that the above second-order component can also be called the observation direction φ The corresponding second harmonic component, the above fourth-order component can also be called the observation direction φ The corresponding fourth harmonic component.

[0072] In addition, the above formula (10) and the above formula (11) can be further rewritten as a weighted sum of a sine component and a cosine component, which can be specifically expressed as follows: (12) in, (13) in, a n ( θ ) express n ( n = 0, 2, 4) order Fourier transform corresponding to the cosine component, b n ( θ ) express n ( n = 0,2,4) order Fourier corresponding sine components. Moreover, from the above formula (11) or formula (12), it can be seen that the orientation of the crack symmetry axis is φ sym and a 2 ( θ ) 、 b 2 ( θ ) 、 a 4 ( θ ) and b 4 ( θ ) related.

[0073] Optionally, for azimuth elastic impedance data uniformly sampled at observation locations, when there are X observation locations (in terms of incident angle θ Taking 22° as an example, there are 6 observation positions.φ , 15°, 45°, 75°, 105°, 135°, and 165°, respectively), the discrete Fourier transform can be used to calculate n ( n = 0, 2, 4) order Fourier transform corresponding to the cosine and sine components, that is: (14) Since the azimuth response of the crack symmetry axis caused by the fourth-order term of the Fourier series is much smaller than the azimuth response of the crack symmetry axis caused by the second-order term. Therefore, the crack density can be determined based only on the second harmonic component corresponding to the second harmonic included in the Fourier series, thereby improving the efficiency of determining or predicting the crack density. In an optional implementation, the server can obtain the second harmonic component corresponding to the second harmonic from multiple harmonic components; then, based on the sine component and cosine component of the second harmonic component, determine the Fourier coefficient corresponding to the second harmonic; finally, determine the crack density based on the Fourier coefficient and the first part of the Fourier coefficient except the crack density parameter.

[0074] Optionally, when determining the Fourier coefficient corresponding to the second harmonic based on the sine component and cosine component of the second harmonic component, the server can determine the orientation of the crack symmetry axis set for the target area based on the sine component and the cosine component, thereby determining the sign of the Fourier coefficient based on the sine component and the orientation of the crack symmetry axis, and determining the size of the Fourier coefficient based on the sine component and the cosine component. The calculation formula for the orientation of the crack symmetry axis can be specifically expressed as follows: (15) in, φ sym represents the orientation of the crack symmetry axis corresponding to the second harmonic component, a 2 ( θ ) represents the cosine component corresponding to the second-order Fourier transform, that is, the cosine component of the second harmonic component, b 2 ( θ ) represents the sinusoidal component corresponding to the second-order Fourier transform, that is, the sinusoidal component of the second harmonic component. It should be noted that the orientation of the crack symmetry axis calculated by the above formula is φ sym The value range is [0° , 90°].

[0075] When the actual crack symmetry axis is φ' > 90°, the prediction result of the crack symmetry axis orientation has 90° ambiguity. Specifically: when the Fourier coefficient corresponding to the second harmonic r 2 ( θ ) > 0, ifa 2 ( θ ) and cos ( 2φ sym ) signs are consistent, then the actual crack symmetry axis orientation φ' = φ sym , otherwise, the actual crack symmetry axis orientation φ' = φ sym + 90°; when the Fourier coefficient corresponding to the second harmonic r 2 ( θ ) < 0, if a 2 ( θ ) and cos ( 2φ sym ) has the opposite sign, then the actual crack symmetry axis orientation φ' = φ sym , otherwise, the actual crack symmetry axis orientation φ' = φ sym +90°.

[0076] The calculation formula of the Fourier coefficient corresponding to the second harmonic component can be specifically expressed as follows: (16) in, r 2 ( θ ) represents the Fourier coefficient corresponding to the second harmonic, sign [] is a symbolic function, sign [ a 2 ( θ ) / cos ( 2φ sym )] represents the sign of the Fourier coefficient corresponding to the second harmonic, Indicates the size of the Fourier coefficient corresponding to the second harmonic.

[0077] Based on the above method, by determining the sign of the second-order component of the azimuthal elastic impedance (i.e. sign [ a 2 ( θ ) / cos ( 2 φ sym )]), the 90° ambiguity in the prediction of the crack symmetry axis orientation can be eliminated.

[0078] Furthermore, after determining the sign and magnitude of the Fourier coefficient corresponding to the second harmonic (i.e., determining the Fourier coefficient corresponding to the second harmonic), the server can determine the magnitude of the crack density in the target area based on the Fourier coefficient and the first part of the Fourier coefficient except the crack density parameter. Optionally, from the above formula (11), when the second-order component of the azimuthal elastic impedance is extracted, r 2 ( θ ) (i.e., determining the Fourier coefficient corresponding to the second harmonic) When calculating the crack density in the target area, the calculation formula of the crack density can be specifically expressed as follows: (17) It is understandable that before determining the Fourier coefficient corresponding to the second harmonic based on the sine component and cosine component of the second harmonic component, the server can also obtain the incident angle and the first angle of the target area, thereby obtaining the sine component based on the incident angle, the first angle and the cosine integral result of the first angle included in the third calculation method; and obtaining the cosine component based on the incident angle, the first angle and the sine integral result of the first angle included in the third calculation method. That is, the server can determine the sine component of the second harmonic component based on the above formula (14) a 2 ( θ ) and cosine components b 2 ( θ ).

[0079] It can be seen that first, the azimuthal elastic impedance equation is rewritten into the Fourier series expansion form through mathematical transformation, and the second-order component of the elastic impedance is extracted; secondly, the azimuth of the crack symmetry axis is obtained through the second-order Fourier cosine coefficient and sine coefficient; then, the sign of the second-order component is determined according to the incident angle and the ratio between the shear wave modulus and the longitudinal wave modulus, and the predicted azimuth of the crack symmetry axis is corrected; finally, the crack density can be accurately calculated through the obtained second-order component.

[0080] In summary, in the method for determining the fracture density provided in the embodiment of the present application, when it is determined that the fracture dip in the target area meets the estimated fracture dip condition, the calculation method of the azimuthal seismic reflection coefficient under the HTI medium, that is, the first calculation method, can be used as the first calculation method of the azimuthal seismic reflection coefficient corresponding to the target area. Then, based on the mapping relationship between at least one calculation parameter included in the first calculation method and the fracture density parameter, the first calculation method is modified to obtain the second calculation method of the azimuthal seismic reflection coefficient. Finally, based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, the third calculation method corresponding to the azimuthal elastic impedance is determined, and the fracture density in the target area is determined based on the Fourier series corresponding to the third calculation method. In this way, since the calculation method of the azimuthal seismic reflection coefficient under the HTI medium and the fracture density parameter can directly describe the fracture characteristics of the target area (such as a formation with high-angle fractures or vertical fractures), there is no need to indirectly indicate the fracture characteristics in the formation with high-angle fractures or vertical fractures through fracture weakness parameters and anisotropy parameters, thereby improving the accuracy of fracture density prediction.

[0081] Further, based on the same technical concept, the embodiment of the present application provides a device for determining crack density, and the device for determining crack density is used to implement the above method flow of the embodiment of the present application. Figure 3 As shown, the determination 300 of the crack density may include: an acquisition module 301, a modification module 302 and a determination module 303, wherein: The acquisition module 301 is used to acquire the fracture dip in the target area, and when it is determined that the fracture dip meets the preset fracture dip condition, acquire a first calculation method of the azimuthal seismic reflection coefficient corresponding to the target area; the first calculation method is a calculation method of the azimuthal seismic reflection coefficient under the HTI medium; A modification module 302 is used to modify the first calculation method based on the mapping relationship between at least one calculation parameter included in the first calculation method and the fracture density parameter, so as to obtain a second calculation method for the azimuthal seismic reflection coefficient; The determination module 303 is used to determine a third calculation method corresponding to the azimuthal elastic impedance based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, and determine the fracture density in the target area based on the Fourier series corresponding to the third calculation method.

[0082] In an optional embodiment, the at least one calculated parameter includes: a normal weakness parameter and a tangential weakness parameter; When modifying the first calculation method based on the mapping relationship between at least one calculation parameter included in the first calculation method and the fracture density parameter, the modification module 302 is specifically used to: Based on the ratio between the shear wave modulus and the longitudinal wave modulus in the target area and the crack density parameter, the mapping relationship between the normal weakness parameter and the tangential weakness parameter and the crack density parameter is constructed; The first calculation method is modified based on the two constructed mapping relationships.

[0083] In an optional embodiment, when determining the third calculation method corresponding to the azimuthal elastic impedance based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, the determination module 303 is specifically used to: Based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, a fourth calculation method corresponding to the azimuthal elastic impedance is obtained; The fourth calculation method is integrated and indexed to obtain the third calculation method.

[0084] In an optional embodiment, when determining the crack density in the target area based on the Fourier series corresponding to the third calculation method, the determination module 303 is specifically used to: Performing logarithm processing on the third calculation method to obtain the third calculation method after logarithm processing, and performing Fourier series expansion processing on the third calculation method after logarithm processing to obtain a Fourier series; Based on the multiple harmonic components included in the Fourier series, the crack density is determined.

[0085] In an optional embodiment, when determining the crack density based on a plurality of harmonic components included in the Fourier series, the determination module 303 is specifically configured to: From the plurality of harmonic components, obtaining a second harmonic component corresponding to the second harmonic; Determine the Fourier coefficient corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component; The fracture density is determined based on the Fourier coefficients and the first portion of the Fourier coefficients excluding the fracture density parameter.

[0086] In an optional embodiment, when determining the Fourier coefficient corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component, the determination module 303 is specifically used to: Based on the sine component and the cosine component, the orientation of the crack symmetry axis set for the target area is determined; The sign of the Fourier coefficient is determined based on the sine component and the orientation of the crack symmetry axis, and the magnitude of the Fourier coefficient is determined based on the sine component and the cosine component.

[0087] In an optional embodiment, before determining the Fourier coefficient corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component, the determination module 303 is further configured to: Obtaining the incident angle and the first angle of the target area; the first angle is the angle between the observation azimuth of the target area and the azimuth of the crack symmetry axis; Obtaining a sine component based on the incident angle, the first angle, and a cosine integral result of the first angle included in the third calculation method; And, based on the incident angle, the first angle, and the sine integration result of the first angle included in the third calculation method, a cosine component is obtained.

[0088] Based on the description of the above method embodiment and device embodiment, the exemplary embodiment of the present invention further provides an electronic device, including: at least one processor; and a memory connected to the at least one processor in communication. The memory stores a computer program that can be executed by the at least one processor, and the computer program is used to enable the electronic device to perform the method according to the embodiment of the present invention when executed by the at least one processor.

[0089] An embodiment of the present application also provides a non-transitory computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor of a computer, is used to cause the computer to execute a method according to an embodiment of the present application.

[0090] An embodiment of the present application also provides a computer program product, including a computer program, wherein the computer program, when executed by a processor of a computer, is used to cause the computer to execute a method according to an embodiment of the present application.

[0091] See also Figure 4 As shown, the structured block diagram of the electronic device 400 that can be used as the server or client of the present application will now be described, which is an example of the hardware device that can be applied to various aspects of the present application. The electronic device is intended to represent the computer device of various forms of digital electronics, such as, laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as, personal digital processing, cellular phones, smart phones, wearable devices and other similar computing devices. The components shown herein, their connections and relationships, and their functions are only used as examples, and are not intended to limit the implementation of the present application described herein and / or required.

[0092] like Figure 4As shown, the electronic device 400 includes a computing unit 401, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 402 or a computer program loaded from a storage unit 408 to a random access memory (RAM) 403. In the RAM 403, various programs and data required for the operation of the device 400 can also be stored. The computing unit 401, the ROM 402, and the RAM 403 are connected to each other via a bus 404. An input / output (I / O) interface 405 is also connected to the bus 404.

[0093] A plurality of components in the electronic device 400 are connected to the I / O interface 405, including: an input unit 406, an output unit 407, a storage unit 408, and a communication unit 409. The input unit 406 may be any type of device capable of inputting information to the electronic device 400, and the input unit 406 may receive input digital or character information, and generate key signal inputs related to user settings and / or function control of the electronic device. The output unit 407 may be any type of device capable of presenting information, and may include but is not limited to a display, a speaker, a video / audio output terminal, a vibrator, and / or a printer. The storage unit 408 may include but is not limited to a disk, an optical disk. The communication unit 409 allows the electronic device 400 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks, and may include but is not limited to a modem, a network card, an infrared communication device, a wireless communication transceiver, and / or a chipset, such as a Bluetooth device, a WiFi device, a worldwide interoperability for microwave access (WiMax) device, a cellular communication device, and / or the like.

[0094] The computing unit 401 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the computing unit 401 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The computing unit 401 performs the various methods and processes described above. For example, in some embodiments, the above-mentioned method for determining the crack density may be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit 408. In some embodiments, part or all of the computer program may be loaded and / or installed on the electronic device 400 via the ROM 402 and / or the communication unit 409. In some embodiments, the computing unit 401 may be configured to perform the above-mentioned method for determining the crack density in any other appropriate manner (e.g., by means of firmware).

[0095] The program code for implementing the method of the present application can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that the program code, when executed by the processor or controller, implements the functions / operations specified in the flow chart and / or block diagram. The program code can be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0096] In the context of the present application, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or device, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a RAM, a ROM, an erasable programmable read-only memory (EPROM) or a flash memory, an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0097] As used herein, the terms "machine-readable medium" and "computer-readable medium" refer to any computer program product, apparatus, and / or device (e.g., disk, optical disk, memory, programmable logic device (PLD)) for providing machine instructions and / or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term "machine-readable signal" refers to any signal for providing machine instructions and / or data to a programmable processor.

[0098] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device (e.g., a cathode ray tub (CRT) or a liquid crystal display (LCD) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the computer. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0099] The systems and techniques described herein may be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), and the Internet.

[0100] A computer system may include clients and servers. Clients and servers are generally remote from each other and usually interact through a communication network. The relationship of client and server is generated by computer programs running on respective computers and having a client-server relationship to each other.

[0101] Furthermore, it should be understood that what is disclosed above is only a preferred embodiment of the present application, and certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope covered by the present application.

Claims

1. A method for determining crack density, characterized in that: include: Obtaining a fracture dip in a target area, and when determining that the fracture dip satisfies a preset fracture dip condition, obtaining a first calculation method of an azimuthal seismic reflection coefficient corresponding to the target area; the first calculation method is a calculation method of the azimuthal seismic reflection coefficient in a horizontal transversely isotropic HTI medium; Based on the mapping relationship between at least one calculation parameter included in the first calculation method and the fracture density parameter, the first calculation method is modified to obtain a second calculation method for the azimuthal seismic reflection coefficient; Based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, a third calculation method corresponding to the azimuthal elastic impedance is determined, and the fracture density in the target area is determined based on the Fourier series corresponding to the third calculation method.

2. The method according to claim 1, characterized in that The at least one calculated parameter includes: a normal weakness parameter and a tangential weakness parameter; The modifying of the first calculation method based on the mapping relationship between at least one calculation parameter included in the first calculation method and the crack density parameter comprises: Based on the ratio between the shear wave modulus and the longitudinal wave modulus of the target area and the crack density parameter, a mapping relationship between the normal weakness parameter and the tangential weakness parameter and the crack density parameter is constructed; The first calculation method is modified based on the two constructed mapping relationships.

3. The method according to claim 1, characterized in that The determining, based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, a third calculation method corresponding to the azimuthal elastic impedance includes: Based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, a fourth calculation method corresponding to the azimuthal elastic impedance is obtained; The fourth calculation method is integrated and indexed to obtain the third calculation method.

4. The method according to any one of claims 1 to 3, characterized in that The determining the crack density in the target area based on the Fourier series corresponding to the third calculation method includes: Performing logarithm processing on the third calculation method to obtain the third calculation method after logarithm processing, and performing Fourier series expansion processing on the third calculation method after logarithm processing to obtain the Fourier series; The crack density is determined based on a plurality of harmonic components included in the Fourier series.

5. The method according to claim 4, characterized in that The determining the crack density based on the multiple harmonic components included in the Fourier series comprises: From the multiple harmonic components, obtaining a second harmonic component corresponding to the second harmonic; Determine the Fourier coefficient corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component; The fracture density is determined based on the Fourier coefficients and a first portion of the Fourier coefficients excluding the fracture density parameter.

6. The method according to claim 5, characterized in that The determining, based on the sine component and the cosine component of the second harmonic component, the Fourier coefficient corresponding to the second harmonic comprises: Based on the sine component and the cosine component, determining the orientation of the crack symmetry axis set for the target area; The sign of the Fourier coefficient is determined based on the sine component and the orientation of the crack symmetry axis, and the magnitude of the Fourier coefficient is determined based on the sine component and the cosine component.

7. The method according to claim 6, characterized in that Before determining the Fourier coefficient corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component, the method further includes: Acquire the incident angle and the first angle of the target area; the first angle is the angle between the observation azimuth of the target area and the azimuth of the crack symmetry axis; Obtaining the sine component based on the incident angle, the first angle, and a cosine integral result of the first angle included in the third calculation method; And, the cosine component is obtained based on the incident angle, the first angle and the sine integration result of the first angle included in the third calculation method.

8. A device for determining crack density, characterized in that: include: An acquisition module, used to acquire a fracture dip in a target area, and when it is determined that the fracture dip satisfies a preset fracture dip condition, acquire a first calculation method of an azimuthal seismic reflection coefficient corresponding to the target area; The first calculation method is a method for calculating the azimuthal seismic reflection coefficient in a horizontal transversely isotropic HTI medium; A modification module, configured to modify the first calculation method based on a mapping relationship between at least one calculation parameter included in the first calculation method and a fracture density parameter, to obtain a second calculation method for the azimuthal seismic reflection coefficient; A determination module is used to determine a third calculation method corresponding to the azimuthal elastic impedance based on the second calculation method and a mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, and to determine the fracture density in the target area based on the Fourier series corresponding to the third calculation method.

9. An electronic device, comprising: processor; as well as Memory for storing programs, The program comprises instructions, which, when executed by the processor, cause the processor to perform the method according to any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium storing computer instructions, characterized in that: The computer instructions are used to cause the computer to execute the method according to any one of claims 1 to 7.

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