A method, device, electronic device and storage medium for determining crack density

Abstract

The present application provides a method, apparatus, electronic device, and storage medium for determining fracture density, which relates to the technical field of geological exploration. In the present application, when it is determined that the fracture dip angle in the target area satisfies a preset fracture dip angle condition, a first calculation method for the azimuthal seismic reflection coefficient corresponding to the target area is obtained; the first calculation method is the calculation method for the azimuthal seismic reflection coefficient under a horizontally transverse isotropic 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, improving the accuracy of fracture density prediction.

Description

Technical Field

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

[0002] With the increasing complexity of exploration targets and the continuous increase of exploration requirements, fractured gas-bearing reservoirs have become important targets for oil and gas exploration. In fractured gas-bearing reservoirs, fractures, as reservoir 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] When seismic waves propagate in fractured formations, the kinematic and dynamic parameters of seismic waves usually exhibit azimuthal anisotropy. Related technologies often use the azimuthal anisotropy law of seismic data to predict the fracture density of fractured gas-bearing reservoirs. Exemplarily, the development degree 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 fracture density prediction method to predict the fracture density of formations with high-angle fractures or vertical fractures, the fracture characteristics in formations with high-angle fractures or vertical fractures cannot be directly described by fracture weakness parameters and anisotropy parameters and have uncertainties, resulting in low accuracy of fracture density prediction. Summary of the Invention

[0005] Embodiments of the present application provide a method, device, electronic device and storage medium for determining fracture density, so as to improve the accuracy of fracture density prediction when predicting the 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 fracture density, the method comprising:

[0007] Obtain the fracture dip angle in the target area, and when it is determined that the fracture dip angle meets a preset fracture dip angle condition, obtain a first calculation method for the azimuthal seismic reflection coefficient corresponding to the target area; the first calculation method is the calculation method for the azimuthal seismic reflection coefficient in a horizontal transversely isotropic (HTI) medium;

[0008] 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, to obtain a second calculation method for the azimuthal seismic reflection coefficient;

[0009] Based on the second calculation method and the mapping relationship between azimuthal elastic impedance and azimuthal seismic reflection coefficient, determine the 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.

[0010] In an alternative embodiment, at least one calculation parameter includes: a normal weakness parameter and a tangential weakness parameter;

[0011] 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, including:

[0012] Based on the ratio between the shear wave modulus and the compressional wave modulus of the target area and the fracture density parameter, construct the mapping relationships between the normal weakness parameter and the tangential weakness parameter and the fracture density parameter respectively;

[0013] Modify the first calculation method based on the two constructed mapping relationships.

[0014] In an alternative embodiment, based on the second calculation method and the mapping relationship between azimuthal elastic impedance and azimuthal seismic reflection coefficient, determine the third calculation method corresponding to the azimuthal elastic impedance, including:

[0015] Based on the second calculation method and the mapping relationship between azimuthal elastic impedance and azimuthal seismic reflection coefficient, obtain the fourth calculation method corresponding to the azimuthal elastic impedance;

[0016] Perform integral processing and exponential processing on the fourth calculation method to obtain the third calculation method.

[0017] In an alternative embodiment, determine the fracture density in the target area based on the Fourier series corresponding to the third calculation method, including:

[0018] Perform logarithmic processing on the third calculation method to obtain the logarithmically processed third calculation method, and perform Fourier series expansion processing on the logarithmically processed third calculation method to obtain the Fourier series;

[0019] Determine the fracture density based on multiple harmonic components included in the Fourier series.

[0020] In an alternative embodiment, determine the fracture density based on multiple harmonic components included in the Fourier series, including:

[0021] From multiple harmonic components, obtain the second harmonic component corresponding to the second harmonic;

[0022] Based on the sine component and cosine component of the second harmonic component, determine the Fourier coefficient corresponding to the second harmonic;

[0023] Determine the fracture density based on the Fourier coefficients and the first part of the Fourier coefficients excluding the fracture density parameter.

[0024] In an alternative embodiment, determining the Fourier coefficients corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component includes:

[0025] Determine the azimuth of the fracture symmetry axis set for the target area based on the sine component and the cosine component;

[0026] Determine the sign of the Fourier coefficients based on the sine component and the azimuth of the fracture symmetry axis, and determine the magnitude of the Fourier coefficients based on the sine component and the cosine component.

[0027] In an alternative embodiment, before determining the Fourier coefficients corresponding to the second harmonic based on the sine component and the cosine component of the second harmonic component, it further includes:

[0028] Obtain the incident angle and the first included angle of the target area; the first included angle is the included angle between the observation azimuth of the target area and the azimuth of the fracture symmetry axis;

[0029] Obtain the sine component based on the incident angle, the first included angle, and the cosine integral result of the first included angle included in the third calculation method;

[0030] And obtain the cosine component based on the incident angle, the first included angle, and the sine integral result of the first included angle included in the third calculation method.

[0031] In a second aspect, an embodiment of the present application further provides a device for determining fracture density, and the device includes:

[0032] An acquisition module, configured to acquire the fracture dip angle in the target area, and when it is determined that the fracture dip angle meets a preset fracture dip angle condition, acquire the first calculation method of the azimuth seismic reflection coefficient corresponding to the target area; the first calculation method is the calculation method of the azimuth seismic reflection coefficient in the HTI medium;

[0033] A modification module, configured 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, to obtain the second calculation method of the azimuth seismic reflection coefficient;

[0034] A determination module, configured to determine the third calculation method corresponding to the azimuth elastic impedance based on the second calculation method and the mapping relationship between the azimuth elastic impedance and the azimuth seismic reflection coefficient, and determine the fracture density in the target area based on the Fourier series corresponding to the third calculation method.

[0035] In an alternative embodiment, the at least one calculation parameter includes: a normal weakness parameter and a tangential weakness parameter;

[0036] When modifying the first calculation method based on the mapping relationships between at least one calculation parameter included in the first calculation method and the fracture density parameter respectively, the modification module is specifically configured to:

[0037] Based on the ratio between the shear wave modulus and the compressional wave modulus of the target area, and the fracture density parameter, construct the mapping relationships between the normal weakness parameter and the tangential weakness parameter and the fracture density parameter respectively;

[0038] Modify the first calculation method based on the two constructed mapping relationships.

[0039] In an alternative 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 configured to:

[0040] Based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, obtain the fourth calculation method corresponding to the azimuthal elastic impedance;

[0041] Perform integral processing and exponential processing on the fourth calculation method to obtain the third calculation method.

[0042] In an alternative embodiment, when determining the fracture density in the target area based on the Fourier series corresponding to the third calculation method, the determination module is specifically configured to:

[0043] 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;

[0044] Determine the fracture density based on multiple harmonic components included in the Fourier series.

[0045] In an alternative embodiment, when determining the fracture density based on multiple harmonic components included in the Fourier series, the determination module is specifically configured to:

[0046] Obtain the second harmonic component corresponding to the second harmonic from multiple harmonic components;

[0047] Based on the sine component and the cosine component of the second harmonic component, determine the Fourier coefficient corresponding to the second harmonic;

[0048] Determine the fracture density based on the Fourier coefficient and the first part other than the fracture density parameter in the Fourier coefficient.

[0049] In an alternative 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 configured to:

[0050] Based on the sine component and the cosine component, determine the azimuth of the crack symmetry axis set for the target area;

[0051] Based on the sine component and the azimuth of the crack symmetry axis, determine the sign of the Fourier coefficient, and based on the sine component and the cosine component, determine the magnitude of the Fourier coefficient.

[0052] In an alternative 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 determining module is further configured to:

[0053] Obtain the incident angle and the first included angle of the target area; the first included angle is the included angle between the observation azimuth of the target area and the azimuth of the crack symmetry axis;

[0054] Based on the incident angle, the first included angle, and the cosine integral result of the first included angle included in the third calculation method, obtain the sine component;

[0055] And, based on the incident angle, the first included angle, and the sine integral result of the first included angle included in the third calculation method, obtain the cosine component.

[0056] In a third aspect, an embodiment of the present application further provides an electronic device, including:

[0057] A processor; and

[0058] A memory storing a program,

[0059] wherein the program includes instructions that, when executed by the processor, cause the processor to execute the method for determining the crack density as described in the first aspect.

[0060] 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 cause a computer to execute the method for determining the crack density as described in the first aspect.

[0061] In a fifth aspect, the present application provides a computer program product, which, when called by a computer, causes the computer to execute the steps of the method for determining the crack density as described in the first aspect.

[0062] The beneficial effects of the present application are as follows:

[0063] In the method for determining the fracture density provided in the embodiments of the present application, when it is determined that the fracture dip angle in the target area satisfies the budgeted fracture dip angle condition, the calculation method of the azimuthal seismic reflection coefficient below 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 relationships between at least one calculation parameter included in the first calculation method and the fracture density parameter respectively, 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. By using this method, since the fracture characteristics of the target area (such as the formation with high-angle fractures or vertical fractures) can be directly described by the calculation method of the azimuthal seismic reflection coefficient below the HTI medium and the fracture density parameter, there is no need to indirectly indicate the fracture characteristics in the formation with high-angle fractures or vertical fractures through the fracture weakness parameter and the anisotropy parameter, thereby improving the accuracy of fracture density prediction.

[0064] In addition, other features and advantages of the present application will be described in the subsequent specification, and part of them will become obvious from the specification, or will be understood by implementing the present application. The objectives and other advantages of the present application can be achieved and obtained through the structures specifically pointed out in the written specification, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for the description of 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 to the present application. In the drawings:

[0066] Figure 1 It is a schematic diagram of an optional system architecture applicable to the embodiments of the present application;

[0067] Figure 2 It is a schematic diagram of the implementation process of a method for determining fracture density provided by the embodiments of the present application;

[0068] Figure 3 It is a schematic diagram of the structure of a device for determining fracture density provided by the embodiments of the present application;

[0069] Figure 4 It is a schematic diagram of the structure of an electronic device provided by the embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0070] Embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although some embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present application. It should be understood that the drawings and embodiments of the present application are only for exemplary purposes and are not used to limit the protection scope of the present application.

[0071] It should be understood that the various steps recited in the method embodiments of the present application can be executed in a different order and / or in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present application is not limited in this regard.

[0072] The term "including" and its variants used herein are open-ended, that is, "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts such as "first" and "second" mentioned in the present application are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence relationship of the functions performed by these devices, modules or units.

[0073] It should be noted that the modifications of "one" and "plural" mentioned in the present application are illustrative rather than restrictive. Those skilled in the art should understand that unless clearly stated otherwise in the context, it should be understood as "one or more".

[0074] The names of the messages or information exchanged between multiple devices in the embodiments of the present application are only for illustrative purposes and are not used to limit the scope of these messages or information.

[0075] Some terms in the embodiments of the present application are explained below to facilitate the understanding of those skilled in the art.

[0076] (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 trap. If only oil accumulates in the trap, it is called a pure oil reservoir (or oil reservoir). If only natural gas accumulates, it is called a pure gas reservoir (or gas reservoir). The oil and gas have certain distribution laws and a unified pressure system therein.

[0077] (2) Azimuthal seismic reflection coefficient: A parameter used in seismic exploration to estimate the properties of subsurface rocks, which reflects the ability of seismic waves to reflect in the subsurface medium. The calculation of the azimuthal 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 angle of incidence and the properties of the subsurface medium.

[0078] (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 the exploration of fractured gas reservoirs, the fracture symmetry axis is used to determine the orientation of fractures.

[0079] (4) Longitudinal wave modulus: Also known as the compression modulus, it is a physical quantity that describes the ability of a material to resist deformation when subjected to longitudinal compression or tension.

[0080] (5) Transverse wave modulus: Also known as the shear modulus, it describes the deformation characteristics of a material under shear stress.

[0081] (6) Normal weakness: It refers to the ratio of the elastic modulus of a rock in the normal direction to the elastic modulus in the tangential direction. It reflects the strength and rigidity of the rock perpendicular to the fracture direction. Since the presence of fluids can change the porosity and pressure distribution of the formation, thus affecting the elastic modulus of the formation. Therefore, the normal weakness is very sensitive to the fluid distribution in fractured reservoirs.

[0082] (7) Tangential weakness: It refers to the ratio of the elastic modulus of a rock in the tangential direction to the elastic modulus in the normal direction. It reflects the strength and rigidity of the rock parallel to the fracture direction. Since the flow of fluids in fractures can change the tangential elastic modulus of the formation. Therefore, the tangential weakness is also sensitive to the fluid distribution in fractured reservoirs.

[0083] (8) Azimuthal elastic impedance: A parameter used in seismic exploration to estimate the properties of subsurface rocks, which combines factors such as seismic wave velocity, formation pressure, and temperature, and can reflect geological information such as the porosity and oiliness of the formation. And in seismic exploration, the azimuthal elastic impedance is usually used to indirectly reflect the porosity and oiliness of the formation, which is of great significance for studying the fracture characteristics of reservoirs and fluid identification.

[0084] Based on the above explanations of terms and related terminologies, the design concept of the embodiments of the present application is briefly introduced as follows:

[0085] With the increasing complexity of exploration targets and the continuous growth of exploration demands, fractured gas-bearing reservoirs represented by carbonate rocks, tight sandstones, shales, etc. have become the key focus of researchers. In such oil and gas reservoirs, fractures, as the reservoir space and seepage channels, are important factors affecting the rock properties of gas-bearing reservoirs. Since the kinematic and dynamic parameters of seismic waves usually exhibit azimuthal anisotropy when propagating in fractured formations, using the azimuthal anisotropy law of seismic data to detect fractures has become the main means of fracture prediction.

[0086] Exemplarily, the degree of fracture development in a fractured formation is indirectly indicated through fracture weakness parameters (such as normal weakness or tangential weakness) and anisotropy parameters, that is, the fracture density of the fractured formation is indirectly predicted. However, using the aforementioned fracture density prediction method to predict the fracture density in a formation with high-angle fractures or vertical fractures, it is difficult to obtain an intuitive description of the fracture characteristics in the formation with high-angle fractures or vertical fractures. In addition, due to the large number of parameters in the forward equation, the predicted fracture weakness parameters and anisotropy parameters have great uncertainties, resulting in low accuracy of the prediction results.

[0087] Specifically, most of the existing fracture density prediction methods indirectly indicate the fracture density through ellipse fitting, or obtain the fracture density by converting the predicted anisotropy parameters or fracture weakness parameters. Cumulative errors are easily introduced during the conversion process. In addition, since the anisotropy parameters and fracture weakness parameters contribute less to seismic data, using the conventional seismic multi-parameter simultaneous inversion method to solve the inverse problem is highly ill-posed and has a large amount of uncertainties. These problems make it difficult to quantitatively describe the fracture density, thereby affecting the judgment of gas-bearing reservoirs with high-angle fractures or vertical fractures.

[0088] Therefore, it can be seen that when predicting the fracture density in a formation with high-angle fractures or vertical fractures, how to improve the accuracy of fracture density prediction is an urgent problem to be solved currently. In view of this, to solve or improve the aforementioned problems, the embodiments of the present application provide a method for determining fracture density, which may specifically include: obtaining the fracture dip angle in the target area, and when it is determined that the fracture dip angle meets the preset fracture dip angle condition, obtaining the first calculation method of the azimuthal seismic reflection coefficient corresponding to the target area; the first calculation method is the 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, modifying the first calculation method 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, determining the third calculation method corresponding to the azimuthal elastic impedance, and determining the fracture density in the target area based on the Fourier series corresponding to the third calculation method.

[0089] Based on the above method, due to the influence of the underground tectonic stress field, the fractures in the formation generally exhibit the characteristics of having a certain main arrangement direction and vertical directional distribution. Therefore, under the assumption of the seismic equivalent medium theory, the formation with high-angle fractures or vertical fractures (i.e., the target area) can usually be equivalent to an HTI medium. Thus, the calculation method of the azimuthal seismic reflection coefficient below 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. In this way, the fracture characteristics of the target area can be directly described by the calculation method of the azimuthal seismic reflection coefficient below the HTI medium and the fracture density parameter, without indirectly indicating the fracture characteristics in the formation with high-angle fractures or vertical fractures through the fracture weakness parameter and the anisotropy parameter, improving the accuracy of fracture density prediction.

[0090] In particular, the preferred embodiments of the present application will be described below with reference to the accompanying drawings of 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 without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0091] Refer to Figure 1 As shown, it is a schematic diagram of an optional system architecture applicable to the embodiments of the present application. The system architecture may include: two terminal devices 101 and a server 102. Information interaction can be carried out between each terminal device 101 and the server 102 through a communication network. Among them, the communication methods adopted by the communication network may include: wireless communication methods and wired communication methods. Exemplarily, the terminal device 101 can access the network through cellular mobile communication technology and communicate with the server 102. Among them, the cellular mobile communication technology, for example, includes the fifth-generation mobile networks (5G) technology or the next-generation mobile communication technology.

[0092] Optionally, the terminal device 101 can access the network through a short-range wireless communication method and communicate with the server 102. Among them, the short-range wireless communication method, for example, includes wireless fidelity (Wi-Fi) technology.

[0093] The embodiments of the present application do not impose any restrictions on the number of communication devices involved in the above system architecture. For example, the above system architecture may include more terminal devices, or include fewer terminal devices, or further include other network devices. As Figure 1 As shown, only two terminal devices 101 and a server 102 are taken as examples for description. Below, each of the above communication devices and their respective functions will be briefly introduced.

[0094] The terminal device 101 is a device that can provide voice and / or data connectivity to users and can be a device supporting wired and / or wireless connection methods.

[0095] Exemplarily, the terminal device 101 may include, but is not limited to: mobile phones, tablet computers, laptop computers, handheld computers, mobile internet devices (MIDs), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, wireless terminal devices in industrial control, wireless terminal devices in unmanned driving, wireless terminal devices in smart grids, wireless terminal devices in transportation safety, wireless terminal devices in smart cities, or wireless terminal devices in smart homes, etc.

[0096] In addition, a relevant client may be installed on the terminal device 101. The client may be software, for example, an application (APP), a browser, a short video software, etc., or may also be a web page, a mini-program, etc. It should be noted that in the embodiment of the present application, the terminal device 101 may cause the above-mentioned client related to the determination of crack density to send a determination request (or a prediction request for crack density) for the crack density of the target area to the server 102, so as to perform subsequent method steps such as the determination of the crack density of the target area.

[0097] The server 102 may be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or may also be a cloud server providing 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 network (CDN), and big data and artificial intelligence platforms.

[0098] It is worth noting that in the embodiment of the present application, the server 102 may be used to obtain the crack dip angle in the target area, and when it is determined that the crack dip angle meets the preset crack dip angle condition, obtain the first calculation method of the azimuth 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 crack density parameter, modify the first calculation method to obtain the second calculation method of the azimuth seismic reflection coefficient; finally, based on the second calculation method and the mapping relationship between the azimuth elastic impedance and the azimuth seismic reflection coefficient, determine the third calculation method corresponding to the azimuth elastic impedance, and determine the crack density in the target area based on the Fourier series corresponding to the third calculation method. Among them, the first calculation method is the calculation method of the azimuth seismic reflection coefficient under the HTI medium.

[0099] The method for determining the fracture density provided by the exemplary embodiment of the present application will be described below in combination with the above system architecture and with reference to the accompanying drawings. It should be noted that the above system architecture is only shown for the convenience of understanding the spirit and principle of the present application, and the embodiments of the present application are not limited in this regard.

[0100] Refer to Figure 2 As shown, it is a schematic diagram of the implementation process of a method for determining the fracture density provided by an embodiment of the present application. Taking the server as an example of the execution subject, the specific implementation process of this method is as follows:

[0101] S201: Obtain the fracture dip angle in the target area, and when it is determined that the fracture dip angle meets the preset fracture dip angle condition, obtain the first calculation method of the azimuth seismic reflection coefficient corresponding to the target area.

[0102] Among them, the above preset fracture dip angle condition can be the dip angle range corresponding to high-angle fractures and / or vertical fractures, that is, the preset fracture dip angle condition is: the dip angle range corresponding to high-angle fractures, that is, [70°, 90°), or the dip angle range corresponding to vertical fractures, that is, 90°, or the dip angle range corresponding to high-angle fractures and vertical fractures, that is, [70°, 90°].

[0103] Therefore, when it is determined that the fracture dip angle in the target area meets the above preset fracture dip angle condition, it can be determined that the fractures in the target area are high-angle fractures or vertical fractures, and then the target area is equivalent to an HTI medium.

[0104] The above first calculation method is the calculation method of the azimuth seismic reflection coefficient under the HTI medium. Optionally, the above calculation method of the azimuth seismic reflection coefficient under the HTI medium (i.e., the first calculation method) can be specifically expressed as follows:

[0105] (1)

[0106] Among them, R pp ( θ , ) represents the azimuth seismic reflection coefficient, θ represents the incident angle of the target area, represents the observation azimuth of the target area φ and the azimuth of the fracture symmetry axis φ sym between the angles, that is, the first angle, M and μ represent the longitudinal wave modulus and the transverse wave modulus under the isotropic background, ρ represents the density of the target area, δN and δ T represent the normal weakness parameter and the tangential weakness parameter of the fracture. The symbol "-" at the top of the model parameter represents the average value of the model parameters of the upper and lower layer media in the target area, and the symbol "Δ" represents the difference between the model parameters of the upper and lower layer media in the target area. g = μ / M .

[0107] S202: 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 to obtain a second calculation method for the azimuthal seismic reflection coefficient.

[0108] Since there is a mapping relationship between some of the calculation parameters included in the first calculation method (i.e., the above-mentioned at least one calculation parameter, such as the normal weakness parameter δ N and the tangential weakness parameter δ T ) and the fracture density parameter. Therefore, the server can optimize the first calculation method into a calculation method carrying the fracture density parameter through the mapping relationship between the foregoing partial calculation parameters and the fracture density parameter, thereby reducing the calculation parameters of the azimuthal seismic reflection coefficient, reducing the uncertainty of the calculation parameters, and further improving the accuracy of subsequent prediction of the fracture density.

[0109] Optionally, the above-mentioned at least one calculation parameter may include: the normal weakness parameter and the tangential weakness parameter. Therefore, the mapping relationship between each of the above-mentioned at least one calculation parameter and the fracture density parameter may include: the mapping relationship between the normal weakness parameter and the fracture density parameter (or referred to as the first mapping relationship), and the mapping relationship between the tangential weakness parameter and the fracture density parameter (or referred to as the 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:

[0110] (2)

[0111] Wherein, δ N represents the normal weakness parameter of the fracture, δ T represents the tangential weakness parameter of the fracture, e represents the fracture density in the target area, g represents the ratio between the shear wave modulus μ and the longitudinal wave modulus M in the isotropic background.

[0112] Therefore, when performing step S202, the server can construct the mapping relationships between the normal weakness parameter and the tangential weakness parameter and the fracture density parameter respectively based on the ratio between the shear wave modulus and the P-wave modulus in the target area and the fracture density parameter (i.e., the first mapping relationship and the second mapping relationship recorded in formula (2)), so as to modify the above first calculation method based on the two constructed mapping relationships, and thus obtain the second calculation method of the azimuthal 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, improving the accuracy of fracture density prediction.

[0113] In other words, based on the second calculation method of the above azimuthal seismic reflection coefficient, the first calculation method of the azimuthal seismic reflection coefficient recorded in the above formula (1) of the server, and in combination with the first mapping relationship and the second mapping relationship recorded in the above formula (2), the fracture density parameter can be directly used to characterize the azimuthal seismic reflection coefficient of the target area.

[0114] Exemplarily, the second calculation method of the above azimuthal seismic reflection coefficient can be specifically expressed as follows:

[0115] (3)

[0116] Wherein,

[0117] (4)

[0118] Based on the second calculation method recorded above (i.e., formula (3) and formula (4)), it can be seen that only 4 unknown parameters are included. Compared with the first calculation method, the uncertainty of multi-parameter inversion is greatly reduced; moreover, by adopting the above second calculation method, the anisotropic term is only related to the fracture density parameter, reducing the cumulative error when calculating the fracture density parameter from the inverted fracture weakness parameter or anisotropic parameter, thereby improving the accuracy of fracture prediction.

[0119] S203: Based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, determine the 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.

[0120] When performing seismic inversion using the second calculation method, it is extremely susceptible to seismic wavelets and noise, and it is difficult to determine the fracture density parameter in the target area from the response results. To improve the aforementioned problems, the characteristics of the azimuthal elastic impedance can be combined to realize the prediction of the fracture density in the target area. Therefore, 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 can be determined.

[0121] The mapping relationship between the above azimuthal elastic impedance and the azimuthal seismic reflection coefficient can be specifically expressed as follows:

[0122] (5)

[0123] Among them, R pp ( θ , ) represents the azimuthal seismic reflection coefficient, and Δ EI ( θ , ) represents the difference in azimuthal elastic impedance between the upper and lower layer media in the target area, represents the average value of the azimuthal elastic impedance between the upper and lower layer media in the target area.

[0124] When the elastic parameters on both sides of the reflection interface in the target area are not very different, that is, , the server can obtain the fourth calculation method corresponding to the azimuthal elastic impedance based on the above second calculation method and the mapping relationship between the above azimuthal elastic impedance and the azimuthal seismic reflection coefficient. Optionally, the aforementioned fourth calculation method can be specifically expressed as follows:

[0125] (6)

[0126] Next, perform integral processing and exponential processing on the fourth calculation method, and organize to obtain the calculation method of the normalized azimuthal elastic impedance, that is, the third calculation method. Optionally, the aforementioned third calculation method can be specifically expressed as follows:

[0127] (7)

[0128] Among them, represents the reference value of the azimuthal elastic impedance corresponding to the target area, which can usually be obtained by averaging the logging curves of the target interval. Among them, the target interval is a reservoir included in the deep buried reservoir.

[0129] Furthermore, after the server determines the third calculation method corresponding to the azimuthal elastic impedance, it can predict or determine the fracture density in the target area based on Fourier series analysis. In an optional implementation manner, in order to improve the efficiency of fracture density prediction and reduce the computational complexity, the server can perform logarithmic processing on the third calculation method, obtain the third calculation method after logarithmic processing, and perform Fourier series expansion processing on the third calculation method after logarithmic processing to obtain a Fourier series, so as to determine the fracture density based on multiple harmonic components included in the Fourier series.

[0130] The third calculation method after the above logarithmic processing, that is, the linearized azimuthal elastic impedance expression. Exemplarily, the third calculation method after the above logarithmic processing can be specifically expressed as follows:

[0131] (8)

[0132] Among them,

[0133] (9)

[0134] Since = φ - φ sym , then perform Fourier series expansion on the third calculation method after the above logarithmic processing. Taking the Fourier series of the azimuthal elastic impedance expanded to the 4th order as an example, it can be specifically expressed as follows:

[0135] (10)

[0136] Among them,

[0137] (11)

[0138] Among them, r 0 ( θ ) represents the zero-order component of the azimuthal elastic impedance, E ( θ ) represents the anisotropic terms included in the zero-order component (that is, E ( θ ) e ) except for the fracture density parameter e of the parameter part, r 2 ( θ ) represents the second-order component of the azimuthal elastic impedance, F ( θ ) represents the parameter part except for the fracture density parameter e in the second-order component, r 4 ( θ ) represents the fourth-order component of the azimuthal elastic impedance, G ( θ ) represents the parameter part except for the fracture density parameter e in the fourth-order component.

[0139] It can be understood that the above second-order component can also be called the second harmonic component corresponding to the observation azimuth φ , and the above fourth-order component can also be called the fourth harmonic component corresponding to the observation azimuth φ .

[0140] In addition, the above formula (10) and the above formula (11) can be further rewritten in the form of a weighted sum of sine and cosine components, which can be specifically expressed as follows:

[0141] (12)

[0142] where,

[0143] (13)

[0144] where, a n ( θ ) represents n ( n = 0, 2, 4)the cosine component corresponding to the Fourier of order, b n ( θ ) represents n ( n = 0,2, 4)the sine component corresponding to the Fourier of order. Moreover, from the above formula (11) or formula (12), it can be seen that the crack symmetry axis azimuth φ sym is related to a 2 ( θ ), b 2 ( θ ), a 4 ( θ ) and b 4 ( θ ).

[0145] Optionally, for azimuthal elastic impedance data with uniformly sampled observation azimuths, when it has X observation azimuths (taking the incident angle θ as 22° as an example, there are 6 observation azimuths φ , which are 15°, 45°, 75°, 105°, 135° and 165° in sequence), the discrete Fourier transform can be used to calculate n ( n = 0, 2, 4)the cosine and sine components corresponding to the Fourier of order, that is:

[0146] (14)

[0147] The azimuth response of the crack symmetry axis caused by the fourth-order term of the Fourier series is much smaller than that caused by the second-order term. Therefore, the crack density can be determined only based on the second harmonic component corresponding to the second harmonic in the Fourier series, thereby improving the determination efficiency or prediction efficiency of the crack density. In an alternative 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, based on the Fourier coefficient and the first part of the Fourier coefficient other than the crack density parameter, determine the crack density.

[0148] Optionally, when the server determines the Fourier coefficient corresponding to the second harmonic based on the sine component and cosine component of the second harmonic component, it can determine the azimuth of the crack symmetry axis set for the target area based on the sine component and cosine component, thereby determining the sign of the Fourier coefficient based on the sine component and the azimuth of the crack symmetry axis, and determining the magnitude of the Fourier coefficient based on the sine component and cosine component. Among them, the calculation formula for the azimuth of the crack symmetry axis can be specifically expressed as follows:

[0149] (15)

[0150] Among them, φ sym represents the azimuth of the crack symmetry axis corresponding to the second harmonic component, a 2 ( θ ) represents the cosine component corresponding to the second-order Fourier, that is, the cosine component of the second harmonic component, b 2 ( θ ) represents the sine component corresponding to the second-order Fourier, that is, the sine component of the second harmonic component. It should be noted that the azimuth of the crack symmetry axis φ sym calculated by the above formula has a value range of [0°, 90°].

[0151] When the actual azimuth of the crack symmetry axis φ' > 90°, there is a 90° ambiguity in the prediction result of the azimuth of the crack symmetry axis. Specifically: when the Fourier coefficient corresponding to the second harmonic r 2 ( θ ) > 0, if a 2 ( θ ) and cos ( 2φ sym ) have the same sign, then the actual azimuth of the crack symmetry axis φ' = φ sym , otherwise, the actual azimuth of the crack symmetry axisφ' = φ sym + 90°; When the Fourier coefficient corresponding to the second harmonic r 2 ( θ ) < 0, if a 2 ( θ ) and cos ( 2φ sym ) have opposite signs, then the actual crack symmetry axis orientation φ' = φ sym , otherwise, the actual crack symmetry axis orientation φ' = φ sym + 90°.

[0152] The calculation formula of the Fourier coefficient corresponding to the above-mentioned second harmonic component can be specifically expressed as follows:

[0153] (16)

[0154] Among them, r 2 ( θ ) represents the Fourier coefficient corresponding to the second harmonic, sign [] is the sign function, sign a 2 ( θ ) / cos ( 2φ sym )] represents the sign of the Fourier coefficient corresponding to the second harmonic, represents the magnitude of the Fourier coefficient corresponding to the second harmonic.

[0155] Based on the above method, by determining the sign of the second-order component of the azimuthal elastic impedance (i.e., the value of sign a 2 ( θ ) / cos ( 2 φ sym )]), the 90° ambiguity in predicting the crack symmetry axis orientation can be eliminated.

[0156] Furthermore, after the server determines the sign and magnitude of the Fourier coefficient corresponding to the second harmonic (that is, in determining the Fourier coefficient corresponding to the second harmonic), it can determine the crack density magnitude in the target area based on the Fourier coefficient and the first part of the Fourier coefficient except for the crack density parameter. Optionally, from the above formula (11), it can be seen that when extracting the second-order component of the azimuthal elastic impedance r 2 ( θ ​​) (i.e., determining the Fourier coefficients corresponding to the second harmonic) When calculating the fracture density in the target area, the calculation formula for the fracture density can be specifically expressed as follows:

[0157] (17)

[0158] It can be understood that before the server determines the Fourier coefficients corresponding to the second harmonic based on the sine component and cosine component of the second harmonic component, it can also obtain the incident angle and the first included angle of the target area, so as to obtain the sine component based on the incident angle, the first included angle, and the cosine integral result of the first included angle included in the third calculation method; and, based on the incident angle, the first included angle, and the sine integral result of the first included angle included in the third calculation method, obtain the cosine component. That is, the server can determine the sine component of the second harmonic component based on the above formula (14) a 2 ( θ ) and the cosine component b 2 ( θ ).

[0159] It can be seen that first, the azimuthal elastic impedance equation is rewritten into the form of Fourier series expansion through mathematical transformation, and the second-order component of the elastic impedance is extracted; secondly, the azimuth of the fracture symmetry axis is obtained by the second-order Fourier cosine coefficient and sine coefficient; then, the sign of the second-order component is judged according to the incident angle and the ratio between the shear wave modulus and the compressional wave modulus, and the predicted azimuth of the fracture symmetry axis is corrected; finally, the fracture density can be accurately calculated by the obtained second-order component.

[0160] In summary, in the method for determining the fracture density provided in the embodiments of the present application, when it is determined that the fracture dip angle in the target area meets the budgeted fracture dip angle condition, the calculation method of the azimuthal seismic reflection coefficient below 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 fracture characteristics of the target area (such as the formation of high-angle fractures or vertical fractures) can be directly described by the calculation method of the azimuthal seismic reflection coefficient below the HTI medium and the fracture density parameter, there is no need to indirectly indicate the fracture characteristics in the formation of high-angle fractures or vertical fractures through the fracture weakness parameter and the anisotropy parameter, thereby improving the accuracy of fracture density prediction.

[0161] Furthermore, based on the same inventive concept, an embodiment of the present application provides an apparatus for determining fracture density, which is used to implement the above method flow of the embodiment of the present application. Refer to Figure 3 As shown, the fracture density determination apparatus 300 may include: an acquisition module 301, a modification module 302, and a determination module 303, where:

[0162] The acquisition module 301 is configured to acquire the fracture dip angle in the target area, and when it is determined that the fracture dip angle meets the preset fracture dip angle condition, acquire the first calculation method of the azimuthal seismic reflection coefficient corresponding to the target area; the first calculation method is the calculation method of the azimuthal seismic reflection coefficient under the HTI medium;

[0163] The modification module 302 is configured 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, and obtain the second calculation method of the azimuthal seismic reflection coefficient;

[0164] The determination module 303 is configured to determine 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, and determine the fracture density in the target area based on the Fourier series corresponding to the third calculation method.

[0165] In an optional embodiment, the at least one calculation parameter includes: a normal weakness parameter and a tangential weakness parameter;

[0166] 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 configured to:

[0167] Based on the ratio between the shear wave modulus and the longitudinal wave modulus of the target area and the fracture density parameter, construct the mapping relationship between the normal weakness parameter and the tangential weakness parameter and the fracture density parameter respectively;

[0168] Modify the first calculation method based on the two constructed mapping relationships.

[0169] 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 configured to:

[0170] Based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, obtain the fourth calculation method corresponding to the azimuthal elastic impedance;

[0171] Integrate and exponentiate the fourth calculation method to obtain the third calculation method.

[0172] In an alternative embodiment, when determining the crack density in the target area based on the Fourier series corresponding to the third calculation method, the determining module 303 is specifically configured to:

[0173] Take the logarithm of the third calculation method to obtain the logarithm-processed third calculation method, and perform Fourier series expansion on the logarithm-processed third calculation method to obtain a Fourier series;

[0174] Determine the crack density based on multiple harmonic components included in the Fourier series.

[0175] In an alternative embodiment, when determining the crack density based on multiple harmonic components included in the Fourier series, the determining module 303 is specifically configured to:

[0176] Obtain the second harmonic component corresponding to the second harmonic from multiple harmonic components;

[0177] Determine the Fourier coefficient corresponding to the second harmonic based on the sine component and cosine component of the second harmonic component;

[0178] Determine the crack density based on the Fourier coefficient and the first part of the Fourier coefficient excluding the crack density parameter.

[0179] In an alternative embodiment, when determining the Fourier coefficient corresponding to the second harmonic based on the sine component and cosine component of the second harmonic component, the determining module 303 is specifically configured to:

[0180] Determine the azimuth of the crack symmetry axis set for the target area based on the sine component and cosine component;

[0181] Determine the sign of the Fourier coefficient based on the sine component and the azimuth of the crack symmetry axis, and determine the magnitude of the Fourier coefficient based on the sine component and cosine component.

[0182] In an alternative embodiment, before determining the Fourier coefficient corresponding to the second harmonic based on the sine component and cosine component of the second harmonic component, the determining module 303 is further configured to:

[0183] Obtain the incident angle and the first included angle of the target area; the first included angle is the included angle between the observation azimuth of the target area and the azimuth of the crack symmetry axis;

[0184] Obtain the sine component based on the incident angle, the first included angle, and the cosine integral result of the first included angle included in the third calculation method;

[0185] And, a cosine component is obtained based on the incident angle, the first included angle, and the sine integral result of the first included angle included in the third calculation method.

[0186] Based on the descriptions of the above method embodiments and apparatus embodiments, an exemplary embodiment of the present invention further provides an electronic device, including: at least one processor; and a memory communicatively connected to the at least one processor. The memory stores a computer program executable by the at least one processor, and when the computer program is executed by the at least one processor, it is used to cause the electronic device to execute the method according to the embodiments of the present invention.

[0187] An embodiment of the present application further provides a non-transitory computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor of a computer, it is used to cause the computer to execute the method according to the embodiments of the present application.

[0188] An embodiment of the present application further provides a computer program product, including a computer program, wherein when the computer program is executed by a processor of a computer, it is used to cause the computer to execute the method according to the embodiments of the present application.

[0189] Refer to Figure 4 As shown, a block diagram of an electronic device 400 that can be a server or a client of the present application will now be described. It is an example of a hardware device that can be applied to various aspects of the present application. The electronic device is intended to represent various forms of digital electronic computer devices, such as, a laptop computer, a desktop computer, a workbench, a personal digital assistant, a server, a blade server, a mainframe computer, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as, a personal digital processor, a cellular phone, a smart phone, a wearable device, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present application described and / or claimed herein.

[0190] As Figure 4 shown, the electronic device 400 includes a computing unit 401, which can execute 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 into 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 through a bus 404. An input / output (I / O) interface 405 is also connected to the bus 404.

[0191] Multiple 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 can be any type of device capable of inputting information into the electronic device 400. The input unit 406 can receive input digital or character information and generate key signal inputs related to the user settings and / or function controls of the electronic device. The output unit 407 can be any type of device capable of presenting information and can 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 can include, but is not limited to, magnetic disks and optical disks. The communication unit 409 allows the electronic device 400 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks and can 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.

[0192] The computing unit 401 can be various 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 suitable processor, controller, microcontroller, etc. The computing unit 401 executes the various methods and processes described above. For example, in some embodiments, the method for determining the crack density described above can be implemented as a computer software program tangibly embodied in a machine-readable medium, such as the storage unit 408. In some embodiments, part or all of the computer program can be loaded and / or installed onto the electronic device 400 via the ROM 402 and / or the communication unit 409. In some embodiments, the computing unit 401 can be configured to execute the method for determining the crack density described above in any other suitable manner (e.g., by means of firmware).

[0193] The program code for implementing the methods 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 devices, such that when the program codes are executed by the processor or controller, the functions / operations specified in the flowchart and / or block diagram are implemented. The program code can be executed entirely on the machine, partially on the machine, executed partially on the machine and partially on a remote machine as an independent software package, or executed entirely on a remote machine or server.

[0194] In the context of the present application, a machine-readable medium can be a tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer disk, a hard disk, a RAM, a ROM, an erasable programmable read-only memory (EPROM) or 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.

[0195] As used in the present application, the terms "machine-readable medium" and "computer-readable medium" refer to any computer program product, device, and / or apparatus for providing machine instructions and / or data to a programmable processor (e.g., a disk, an optical disk, a memory, a programmable logic device (PLD)), 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.

[0196] To provide for interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device for displaying information to the user (e.g., a cathode ray tube (CRT) or a liquid crystal display (LCD) monitor); and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the computer. Other kinds of devices can also be used to provide for 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, speech input, or tactile input).

[0197] The systems and techniques described herein can 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 having a graphical user interface or a web browser through which the user can interact with an implementation 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 can 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.

[0198] A computer system can include clients and servers. The clients and servers are generally remote from each other and typically interact through a communication network. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship to each other.

[0199] Also, it should be understood that the above-disclosed is only the preferred embodiment of the present application, and of course cannot be used to limit the scope of the 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 for an azimuthal seismic reflection coefficient corresponding to the target area; wherein the preset fracture dip condition may be a dip range corresponding to a high-angle fracture and / or a vertical fracture, and the dip range corresponding to the high-angle fracture is [70°, 90°), the first calculation method is a calculation method for the azimuthal seismic reflection coefficient in a horizontal transversely isotropic HTI medium, and the first calculation method includes at least one calculation parameter, and the at least one calculation parameter includes: a normal weakness parameter and a tangential weakness parameter; 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; Modify the first calculation method based on the two constructed mapping relationships to obtain a second calculation method for the azimuth seismic reflection coefficient; Based on the second calculation method and the mapping relationship between the azimuthal elastic impedance and the azimuthal seismic reflection coefficient, determining a third calculation method corresponding to the azimuthal elastic impedance; 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; Acquire a second harmonic component corresponding to the second harmonic from a plurality of harmonic components included in the Fourier series; 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.

2. 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.

3. The method according to claim 1, 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.

4. The method according to claim 3, 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.

5. A device for determining crack density, characterized in that: The method for implementing any one of claims 1 to 4 comprises: An acquisition module, used for acquiring a fracture dip in a target area, and when it is determined that the fracture dip satisfies a preset fracture dip condition, acquiring 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; 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.

6. 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 4.

7. 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 4.

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