Anisotropic medium crack prediction method and device

Abstract

The embodiment of the present application provides a method and device for predicting anisotropic medium cracks, the method comprising: determining the post-stack seismic traces corresponding to each azimuth respectively based on the OVT wide azimuth gather data of the target area; determining the frequency gradients within the preset frequency range in each azimuth respectively according to the post-stack seismic traces corresponding to each of the azimuths; performing elliptical fitting on the frequency spectrum gradients corresponding to each of the azimuths, and determining the prediction results of anisotropic medium cracks in the target area based on the corresponding fitting results. The present application can effectively predict anisotropic medium cracks, and can effectively improve the processing efficiency, automation and accuracy of the anisotropic medium crack prediction process.

Description

Technical Field

[0001] The present application relates to the technical field of computer identification of geophysical exploration seismic data, belongs to the category of geophysical exploration data processing and interpretation, and specifically relates to a method and device for predicting fractures in anisotropic media. Background Art

[0002] In the process of petroleum geophysical exploration, in order to better interpret fractured oil and gas reservoirs, it is often necessary to interpret and predict anisotropic medium fractures based on seismic exploration data, so as to interpret geological targets and better predict oil and gas reservoirs. At present, the main methods for predicting anisotropic media include amplitude anisotropy detection, frequency anisotropy detection, velocity anisotropy detection based on OVT wide azimuth gathers, etc. However, in some areas, due to problems such as data noise ratio, these features often cannot detect anisotropic media and cannot effectively predict fractures. Summary of the invention

[0003] In view of the problems in the prior art, the present application provides a method and device for predicting anisotropic medium cracks, which can effectively predict anisotropic medium cracks and effectively improve the processing efficiency, automation and accuracy of the anisotropic medium crack prediction process.

[0004] In order to solve the above technical problems, this application provides the following technical solutions:

[0005] In a first aspect, the present application provides a method for predicting cracks in anisotropic media, comprising:

[0006] Determine the post-stack seismic traces corresponding to each azimuth based on the OVT wide-azimuth gather data in the target area;

[0007] Determine the frequency gradient within the preset frequency range in each azimuth according to the post-stack seismic traces corresponding to each of the azimuths;

[0008] The frequency spectrum gradients corresponding to the respective directions are subjected to ellipse fitting, and the anisotropic medium crack prediction result of the target area is determined based on the corresponding fitting result.

[0009] Furthermore, the post-stack seismic traces corresponding to each azimuth are determined based on the OVT wide azimuth gather data of the target area, including:

[0010] Obtain OVT wide-azimuth gather data in the target area;

[0011] Based on the polar coordinate symmetry of the anisotropic characteristics, the OVT wide azimuth gather data is divided into azimuth angles to obtain corresponding multiple azimuths;

[0012] The OVT wide-azimuth gather data are superimposed according to the divided azimuths to form azimuth-divided post-stack seismic data composed of post-stack seismic traces corresponding to each azimuth.

[0013] Further, the determining of the frequency gradient within a preset frequency range in each azimuth according to the post-stack seismic traces corresponding to each azimuth respectively includes:

[0014] Performing Fourier transformation on the post-stack seismic traces corresponding to each of the azimuths to decompose them into frequency spectra of different frequencies;

[0015] Selecting a spectrum whose spectrum value is greater than a frequency threshold from among the spectrums obtained by decomposition as a target spectrum;

[0016] A frequency gradient within a preset frequency range in each of the directions is determined based on the target frequency spectrum.

[0017] Furthermore, performing ellipse fitting on the frequency spectrum gradients corresponding to each of the orientations includes:

[0018] Displaying the frequency spectrum gradients corresponding to each of the directions in polar coordinates;

[0019] Perform ellipse fitting on the frequency spectrum gradients corresponding to each of the orientations according to the polar coordinate display results to obtain corresponding fitting results;

[0020] The fitting result includes the major axis length, minor axis length and major axis orientation of the ellipse.

[0021] Further, the determining of the anisotropic medium fracture prediction result of the target area based on the corresponding fitting result includes:

[0022] The orientation of the major axis of the ellipse is used as the crack direction of the anisotropic medium;

[0023] Determining the fracture strength of the anisotropic medium according to the ratio of the major axis length to the minor axis length of the ellipse;

[0024] The anisotropic medium fracture prediction result including the fracture direction and fracture strength is output.

[0025] Furthermore, the output includes the anisotropic medium fracture prediction result including the fracture direction and fracture strength, including:

[0026] Determining whether the crack strength is equal to or greater than a strength threshold, and if so, determining that the anisotropic medium has crack characteristics;

[0027] The anisotropic medium fracture prediction result is output, wherein the anisotropic medium fracture prediction result includes fracture direction, fracture strength and information for indicating the existence of fracture characteristics in the anisotropic medium.

[0028] In a second aspect, the present application provides an anisotropic medium crack prediction device, comprising:

[0029] The post-stack seismic trace determination module is used to determine the post-stack seismic traces corresponding to each azimuth based on the OVT wide-azimuth gather data of the target area;

[0030] A frequency gradient determination module, used to determine the frequency gradient within a preset frequency range in each azimuth according to the post-stack seismic traces corresponding to each azimuth;

[0031] The crack prediction module is used to perform ellipse fitting on the frequency spectrum gradients corresponding to each of the orientations, and determine the anisotropic medium crack prediction result of the target area based on the corresponding fitting result.

[0032] Furthermore, the post-stack seismic trace determination module is used to perform the following

[0033] Obtain OVT wide-azimuth gather data in the target area;

[0034] Based on the polar coordinate symmetry of the anisotropic characteristics, the OVT wide azimuth gather data is divided into azimuth angles to obtain corresponding multiple azimuths;

[0035] The OVT wide-azimuth gather data are superimposed according to the divided azimuths to form azimuth-divided post-stack seismic data composed of post-stack seismic traces corresponding to each azimuth.

[0036] Furthermore, the frequency gradient determination module is used to perform the following:

[0037] Performing Fourier transformation on the post-stack seismic traces corresponding to each of the azimuths to decompose them into frequency spectra of different frequencies;

[0038] Selecting a spectrum whose spectrum value is greater than a frequency threshold from among the spectrums obtained by decomposition as a target spectrum;

[0039] A frequency gradient within a preset frequency range in each of the directions is determined based on the target frequency spectrum.

[0040] Furthermore, the crack prediction module includes:

[0041] Ellipse fitting unit, used to perform the following:

[0042] Displaying the frequency spectrum gradients corresponding to each of the directions in polar coordinates;

[0043] Perform ellipse fitting on the frequency spectrum gradients corresponding to each of the orientations according to the polar coordinate display results to obtain corresponding fitting results;

[0044] The fitting result includes the major axis length, minor axis length and major axis orientation of the ellipse.

[0045] Furthermore, the crack prediction module further includes:

[0046] A direction determination unit, used for taking the orientation of the major axis of the ellipse as the crack direction of the anisotropic medium;

[0047] A strength determination unit, configured to determine the fracture strength of the anisotropic medium according to a ratio of a major axis length to a minor axis length of the ellipse;

[0048] The result output unit is used to output the anisotropic medium fracture prediction result including the fracture direction and fracture strength.

[0049] Furthermore, the result output unit is used to perform the following:

[0050] Determining whether the crack strength is equal to or greater than a strength threshold, and if so, determining that the anisotropic medium has crack characteristics;

[0051] The anisotropic medium fracture prediction result is output, wherein the anisotropic medium fracture prediction result includes fracture direction, fracture strength and information for indicating the existence of fracture characteristics in the anisotropic medium.

[0052] In a third aspect, the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the anisotropic medium crack prediction method when executing the program.

[0053] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which implements the anisotropic medium crack prediction method when executed by a processor.

[0054] It can be seen from the above technical scheme that the present application provides a method and device for predicting anisotropic medium fractures, the method comprising: determining the post-stack seismic traces corresponding to each azimuth respectively based on the OVT wide-azimuth gather data of the target area; determining the frequency gradients within the preset frequency range in each azimuth respectively according to the post-stack seismic traces corresponding to each of the said azimuths; performing elliptical fitting on the frequency spectrum gradients corresponding to each of the said azimuths, and determining the prediction results of anisotropic medium fractures in the target area based on the corresponding fitting results, which can effectively predict anisotropic medium fractures, and can effectively improve the processing efficiency, automation and accuracy of the anisotropic medium fracture prediction process, and then can use the anisotropic medium fracture prediction results to improve the interpretation accuracy and efficiency of fracture-type oil and gas reservoirs, and can effectively improve the accuracy and reliability of using the interpretation results of fracture-type oil and gas reservoirs for oil reservoir exploitation and other processing, and effectively save manpower and material costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0056] Figure 1 It is a flow chart of the anisotropic medium crack prediction method in the embodiment of the present application.

[0057] Figure 2 It is a flowchart of step 100 in the anisotropic medium crack prediction method in an embodiment of the present application.

[0058] Figure 3 It is a flowchart of step 200 in the anisotropic medium crack prediction method in an embodiment of the present application.

[0059] Figure 4 It is a first specific flow chart of step 300 in the anisotropic medium crack prediction method in the embodiment of the present application.

[0060] Figure 5 It is a second specific flow chart of step 300 in the anisotropic medium crack prediction method in the embodiment of the present application.

[0061] Figure 6 It is a specific flow chart of step 350 in the anisotropic medium crack prediction method in the embodiment of the present application.

[0062] Figure 7 It is a schematic diagram of the structure of the anisotropic medium crack prediction device in the embodiment of the present application.

[0063] Figure 8 It is a schematic diagram of azimuth angle division in the application example of this application.

[0064] Fig. 9 It is a schematic diagram of spectrum gradient calculation in the application example of this application.

[0065] Fig.10 This is an ellipse fitting effect diagram in the application example of this application.

[0066] Fig.11 It is a schematic diagram of the crack display effect in the application example of this application.

[0067] Fig.12 It is a schematic diagram of the structure of an electronic device in an embodiment of the present application. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0069] The purpose of this application is to provide a method for predicting fractures by using OVT wide azimuth gather data to perform azimuth spectral gradient anisotropy analysis. In this method, the wide azimuth OVT gather data are first divided in azimuth, and the gather data of different azimuths are superimposed. Then, the post-stack seismic data of different azimuths are frequency-divided and transformed using Fourier transform to calculate the rate of change of the spectrum within a specific frequency range of each azimuth. Finally, the rate of change of the spectrum within different azimuths is elliptical fitted, so as to predict the direction of the fracture by the major axis direction of the ellipse, and predict the strength of the fracture by the ratio of the major and minor axes of the ellipse. Interpreters can predict oil and gas reservoirs by the direction and strength of the fractures, and then guide the next step of oilfield development.

[0070] Based on the above content, the present application provides an embodiment of a method for predicting cracks in anisotropic media. Figure 1 The anisotropic medium crack prediction method specifically includes the following contents:

[0071] Step 100: Determine the post-stack seismic traces corresponding to each azimuth based on the OVT wide-azimuth gather data of the target area.

[0072] It can be understood that the offset vector slice OVT technology is a processing method for wide-azimuth seismic data.

[0073] Step 200: According to the post-stack seismic traces corresponding to the respective azimuths, respectively determine the frequency gradient within a preset frequency range in each azimuth.

[0074] It is understandable that the stack migration section is migrated on the basis of the horizontal stack section. The original purpose of its development was to solve the problem of low lateral resolution caused by the spatial misalignment of the inclined reflection layer and the divergence of the diffraction wave in the horizontal stack section. According to the order of stacking and migration, the migration can be divided into pre-stack migration and post-stack migration. The stack migration section belongs to post-stack migration.

[0075] Step 300: performing ellipse fitting on the frequency spectrum gradients corresponding to the respective directions, and determining the anisotropic medium crack prediction result of the target area based on the corresponding fitting results.

[0076] From the above description, it can be seen that the anisotropic medium fracture prediction method provided in the embodiment of the present application can effectively predict anisotropic medium fractures, and can effectively improve the processing efficiency, automation and accuracy of the anisotropic medium fracture prediction process, and then can use the anisotropic medium fracture prediction results to improve the interpretation accuracy and efficiency of fractured oil and gas reservoirs, and can effectively improve the accuracy and reliability of oil reservoir exploitation and other processing using the interpretation results of fractured oil and gas reservoirs, and effectively save manpower and material costs.

[0077] In an embodiment of a method for predicting fractures in anisotropic media, see Figure 2 , step 100 in the anisotropic medium crack prediction method specifically includes the following contents:

[0078] Step 110: Obtain OVT wide-azimuth gather data of the target area.

[0079] Step 120: Based on the polar coordinate symmetry of the anisotropic characteristics, the OVT wide azimuth gather data is divided into azimuth angles to obtain corresponding multiple azimuths.

[0080] Step 130: superimpose the OVT wide-azimuth gather data according to the divided azimuths to form azimuth-divided post-stack seismic data consisting of post-stack seismic traces corresponding to the azimuths.

[0081] Specifically, the OVT wide azimuth gather is divided into azimuths. Due to the polar coordinate symmetry of the anisotropic characteristics of seismic data, the 360-degree full-azimuth gather is evenly divided into a fixed azimuth range at 180 degrees. Usually there are 6 azimuths. The gather data is stacked according to the divided azimuths to form azimuth-divided post-stack seismic data. For each sampling point in the seismic trace, the stacking method is to find the average value through all seismic traces (n is the number of seismic traces).

[0082] In an embodiment of a method for predicting fractures in anisotropic media, see Figure 3 , step 200 in the anisotropic medium fracture prediction method may also specifically include the following contents:

[0083] Step 210: Perform Fourier transform on the post-stack seismic traces corresponding to each of the azimuths to decompose them into frequency spectra with different frequencies.

[0084] Step 220: Select a spectrum whose spectrum value is greater than a frequency threshold from among the spectrums obtained by decomposition as a target spectrum.

[0085] Step 230: Determine a frequency gradient within a preset frequency range in each of the directions based on the target frequency spectrum.

[0086] Specifically, the post-stack seismic data sequence of each azimuth is subjected to a short-time window Fourier transform through a specified window length. The spectrum values ​​are counted, and the frequency corresponding to the maximum spectrum position is found. This frequency is taken as the starting frequency, and the frequency corresponding to the spectrum value close to 0 is taken as the ending frequency. The spectrum values ​​are taken from these spectrum pairs to calculate their spectrum gradients.

[0087] In an embodiment of a method for predicting fractures in anisotropic media, see Figure 4 , step 300 in the anisotropic medium crack prediction method specifically includes the following contents:

[0088] Step 310: Display the frequency spectrum gradients corresponding to the respective directions in polar coordinates.

[0089] Step 320: performing ellipse fitting on the frequency spectrum gradients corresponding to each of the orientations according to the polar coordinate display result to obtain corresponding fitting results; wherein the fitting results include the major axis length, minor axis length and major axis orientation of the ellipse.

[0090] Specifically, the spectrum gradients at different orientations are transformed into discrete points in a rectangular coordinate system according to their corresponding orientations, so as to facilitate ellipse fitting, and the fitted ellipse is displayed on a two-dimensional view.

[0091] In an embodiment of a method for predicting fractures in anisotropic media, see Figure 5 , step 300 in the anisotropic medium crack prediction method further specifically includes the following contents:

[0092] Step 330: taking the orientation of the major axis of the ellipse as the crack direction of the anisotropic medium.

[0093] Step 340: Determine the fracture strength of the anisotropic medium according to the ratio of the major axis length to the minor axis length of the ellipse.

[0094] Step 350: Output the anisotropic medium fracture prediction result including the fracture direction and fracture strength.

[0095] In an embodiment of a method for predicting fractures in anisotropic media, see Figure 6 Step 350 in the anisotropic medium fracture prediction method may also specifically include the following contents:

[0096] Step 351: Determine whether the crack strength is equal to or greater than a strength threshold; if so, determine that the anisotropic medium has crack characteristics.

[0097] Step 352: outputting the anisotropic medium fracture prediction result, wherein the anisotropic medium fracture prediction result includes fracture direction, fracture strength and information for indicating the existence of fracture characteristics in the anisotropic medium.

[0098] Specifically, the direction of the major axis of the ellipse is taken as the crack direction, and the ratio of the major and minor axes of the ellipse is output as the crack strength. A crack strength less than 0.8 is considered to have no crack characteristics.

[0099] In summary, the present application implements a method for predicting fractures using wide-azimuth OVT gathers. The method predicts fractures through the anisotropy of the spectral gradient of gather data in different azimuths. The method is suitable for when the amplitude, frequency, and velocity anisotropy characteristics of the gather data are not obvious and conventional methods cannot be used for fracture prediction. The method is used to predict fractures, thereby more effectively interpreting and developing fractured oil and gas reservoirs.

[0100] From the software level, the present application provides an embodiment of an anisotropic medium crack prediction device for realizing all or part of the content of the anisotropic medium crack prediction method, see Figure 7 The anisotropic medium crack prediction device specifically includes the following contents:

[0101] The post-stack seismic trace determination module 10 is used to determine the post-stack seismic traces corresponding to each azimuth based on the OVT wide azimuth gather data of the target area.

[0102] The frequency gradient determination module 20 is used to determine the frequency gradient within a preset frequency range in each azimuth according to the post-stack seismic traces corresponding to each azimuth.

[0103] The crack prediction module 30 is used to perform ellipse fitting on the frequency spectrum gradients corresponding to each of the directions, and determine the anisotropic medium crack prediction result in the target area based on the corresponding fitting result.

[0104] The embodiment of the anisotropic medium crack prediction device provided in the present application can be specifically used to execute the processing flow of the embodiment of the anisotropic medium crack prediction method in the above embodiment, and its functions are not repeated here, and reference can be made to the detailed description of the above method embodiment.

[0105] From the above description, it can be seen that the anisotropic medium fracture prediction device provided in the embodiment of the present application can effectively predict anisotropic medium fractures, and can effectively improve the processing efficiency, automation level and accuracy of the anisotropic medium fracture prediction process, and then can use the anisotropic medium fracture prediction results to improve the interpretation accuracy and efficiency of fractured oil and gas reservoirs, and can effectively improve the accuracy and reliability of processing such as oil reservoir exploitation using the interpretation results of fractured oil and gas reservoirs, and effectively save manpower and material costs.

[0106] In an embodiment of an anisotropic medium fracture prediction device, the post-stack seismic trace determination module 10 in the anisotropic medium fracture prediction device is used to perform the following contents:

[0107] Step 110: Obtain OVT wide-azimuth gather data of the target area.

[0108] Step 120: Based on the polar coordinate symmetry of the anisotropic characteristics, the OVT wide azimuth gather data is divided into azimuth angles to obtain corresponding multiple azimuths.

[0109] Step 130: superimpose the OVT wide-azimuth gather data according to the divided azimuths to form azimuth-divided post-stack seismic data consisting of post-stack seismic traces corresponding to the azimuths.

[0110] In an embodiment of an anisotropic medium crack prediction device, the frequency gradient determination module 20 in the anisotropic medium crack prediction device is used to perform the following contents:

[0111] Step 210: Perform Fourier transform on the post-stack seismic traces corresponding to each of the azimuths to decompose them into frequency spectra with different frequencies.

[0112] Step 220: Select a spectrum whose spectrum value is greater than a frequency threshold from among the spectrums obtained by decomposition as a target spectrum.

[0113] Step 230: Determine a frequency gradient within a preset frequency range in each of the directions based on the target frequency spectrum.

[0114] In an embodiment of an anisotropic medium crack prediction device, the crack prediction module 30 in the anisotropic medium crack prediction device is specifically used to include the following contents:

[0115] Ellipse fitting unit, used to perform the following:

[0116] Displaying the frequency spectrum gradients corresponding to each of the directions in polar coordinates;

[0117] Perform ellipse fitting on the frequency spectrum gradients corresponding to each of the orientations according to the polar coordinate display results to obtain corresponding fitting results;

[0118] The fitting result includes the major axis length, minor axis length and major axis orientation of the ellipse.

[0119] In an embodiment of an anisotropic medium crack prediction device, the crack prediction module 30 in the anisotropic medium crack prediction device is further specifically configured to include the following contents:

[0120] The wavelet extraction machine learning model building module is used to perform the following:

[0121] A direction determination unit, used for taking the orientation of the major axis of the ellipse as the crack direction of the anisotropic medium;

[0122] A strength determination unit, configured to determine the fracture strength of the anisotropic medium according to a ratio of a major axis length to a minor axis length of the ellipse;

[0123] The result output unit is used to output the anisotropic medium fracture prediction result including the fracture direction and fracture strength.

[0124] In an embodiment of an anisotropic medium crack prediction device, the result output unit in the anisotropic medium crack prediction device is further specifically used to perform the following contents:

[0125] Step 351: Determine whether the crack strength is equal to or greater than a strength threshold; if so, determine that the anisotropic medium has crack characteristics.

[0126] Step 352: outputting the anisotropic medium fracture prediction result, wherein the anisotropic medium fracture prediction result includes fracture direction, fracture strength and information for indicating the existence of fracture characteristics in the anisotropic medium.

[0127] To further illustrate the present scheme, the present application also provides a specific application example of an anisotropic medium fracture prediction method using an anisotropic medium fracture prediction device. First, the wide azimuth OVT gather data is divided into azimuths, and the gather data of different azimuths are superimposed. Then, the Fourier transform is used to perform frequency division transformation on the post-stack seismic data of different azimuths, and the spectrum change rate within the specific frequency range of each azimuth is calculated. Finally, the spectrum change rate within different azimuths is elliptical fitted, so as to predict the fracture direction by the major axis direction of the ellipse, and predict the fracture strength by the major-minor axis ratio of the ellipse. Interpreters can predict oil and gas reservoirs by the direction and strength of the fractures, and then guide the next step of oilfield development.

[0128] The specific implementation steps are as follows:

[0129] 1) The OVT wide azimuth gathers are divided into azimuths. Due to the polar coordinate symmetry of the anisotropic characteristics of seismic data, the 360-degree full-azimuth gathers are evenly divided into fixed azimuth ranges of 180 degrees, usually 6 azimuths.

[0130] 2) The gather data are superimposed according to the divided azimuths to form azimuth post-stack seismic data, with each azimuth being a post-stack seismic trace.

[0131] 3) Perform Fourier transform on the post-stack seismic trace in each azimuth and decompose it into spectra of different frequencies.

[0132] 4) Take the high-frequency spectrum and calculate the frequency gradient within a specific frequency range in each direction.

[0133] 5) Display the spectrum gradients in different directions in polar coordinates and perform ellipse fitting to calculate the major and minor axis lengths and major axis azimuth of the ellipse.

[0134] 6) The direction of the major axis of the ellipse is taken as the crack direction, and the ratio of the major axis to the minor axis of the ellipse is output as the crack strength. A crack strength less than 0.8 is considered to have no crack characteristics.

[0135] Based on the above content, the specific example of the anisotropic medium crack prediction method provided by the application entity of this application is as follows:

[0136] 1) Divide the OVT wide azimuth gather into azimuths. Due to the polar coordinate symmetry of the anisotropic characteristics of seismic data, the 360-degree omnidirectional gather is evenly divided into fixed azimuth ranges according to 180-degree azimuths. Usually there are 6 azimuths, such as Figure 8 shown.

[0137] 2) The gather data are stacked according to the divided azimuths to form azimuth-divided post-stack seismic data. For each sampling point in the seismic trace, the stacking method is to find the average value through all seismic traces (n is the number of seismic traces):

[0138]

[0139] 3) By specifying the window length γ, the post-stack seismic data sequence at each azimuth is Perform a short-time window Fourier transform:

[0140]

[0141]

[0142] F[n] is the input one-dimensional single-channel seismic data, k is the time window length, w is the specific frequency, and t is the spectrum information corresponding to the frequency. After the transformation, the post-stack seismic trace is decomposed into spectra of different frequencies (w, s).

[0143] 4) Count the spectrum values, find the frequency corresponding to the maximum spectrum position, and use this frequency as the starting frequency F start , the frequency corresponding to the spectrum value close to 0 is the end frequency F end . Take the spectral values ​​from these spectral pairs and calculate their spectral gradients:

[0144]

[0145] The corresponding effect of the fitting method is as follows Fig. 9 shown.

[0146] 5) The spectrum gradients G at different orientations are transformed into discrete points in a rectangular coordinate system according to their corresponding orientations θ, so as to facilitate ellipse fitting:

[0147] P i (x,y)=(G i *cos(θ),G i *sin(θ))

[0148] Because the center point of the fitted ellipse is at (0, 0), let the ellipse equation be:

[0149] Ax 2 +Bxy+Cy 2 +Dx+Ey=1

[0150] Calculate the corresponding A, B, C, D, E according to the least squares method:

[0151]

[0152]

[0153]

[0154] The major axis a, minor axis b and rotation angle β of the ellipse are:

[0155]

[0156]

[0157]

[0158] Finally, the fitted ellipse is displayed on a two-dimensional view according to a, b, and β, as shown in Fig.10 shown.

[0159] 6) The direction of the major axis of the ellipse β is taken as the crack direction, and the ratio of the major and minor axes of the ellipse c is taken as the crack strength:

[0160] c=a / b

[0161] Cracks with a strength less than 0.8 are considered to have no crack characteristics. The cracks are displayed on the two-dimensional plane in the form of lines. The length of the line is the crack strength c, and the direction of the line is the orientation β of the crack. The final effect is as follows Fig.11 shown.

[0162] The anisotropic medium crack prediction method provided in the application example of the present application uses OVT wide azimuth gather data for crack prediction. First, the OVT wide azimuth gather data is divided into different azimuth ranges by azimuth, and the seismic traces in different azimuth ranges are superimposed. The stacked seismic traces are subjected to spectral decomposition using Fourier transform, and then the gradient of the spectrum change within a specific frequency range is calculated. Finally, the spectrum gradient is elliptical fitted in polar coordinates, and finally the direction and intensity of the crack are taken as the direction of the ellipse and the ratio of the major and minor axes, thereby realizing crack prediction.

[0163] From the hardware level, the present application provides an embodiment of an electronic device for implementing all or part of the content of the anisotropic medium crack prediction method, and the electronic device specifically includes the following content:

[0164] Fig.12 Schematic block diagram of the device structure of the electronic device 9600 according to an embodiment of the present application. Fig.12 As shown, the electronic device 9600 may include a central processor 9100 and a memory 9140; the memory 9140 is coupled to the central processor 9100. It is worth noting that Fig.12 is exemplary; other types of structures may also be used to supplement or replace this structure to implement telecommunication functions or other functions.

[0165] In one embodiment, the anisotropic medium fracture prediction function may be integrated into a central processing unit, wherein the central processing unit may be configured to perform the following control:

[0166] Step 100: Determine the post-stack seismic traces corresponding to each azimuth based on the OVT wide-azimuth gather data of the target area.

[0167] It can be understood that the offset vector slice OVT technology is a processing method for wide-azimuth seismic data.

[0168] Step 200: According to the post-stack seismic traces corresponding to the respective azimuths, respectively determine the frequency gradient within a preset frequency range in each azimuth.

[0169] It is understandable that the stack migration section is migrated on the basis of the horizontal stack section. The original purpose of its development was to solve the problem of low lateral resolution caused by the spatial misalignment of the inclined reflection layer and the divergence of the diffraction wave in the horizontal stack section. According to the order of stacking and migration, the migration can be divided into pre-stack migration and post-stack migration. The stack migration section belongs to post-stack migration.

[0170] Step 300: performing ellipse fitting on the frequency spectrum gradients corresponding to the respective directions, and determining the anisotropic medium crack prediction result of the target area based on the corresponding fitting results.

[0171] From the above description, it can be seen that the electronic device provided in the embodiment of the present application can effectively predict anisotropic medium fractures, and can effectively improve the processing efficiency, automation and accuracy of the anisotropic medium fracture prediction process, and then can use the anisotropic medium fracture prediction results to improve the interpretation accuracy and efficiency of fractured oil and gas reservoirs, and can effectively improve the accuracy and reliability of oil reservoir exploitation and other processing using the interpretation results of fractured oil and gas reservoirs, and effectively save manpower and material costs.

[0172] In another embodiment, the anisotropic medium crack prediction device can be configured separately from the central processing unit 9100. For example, the anisotropic medium crack prediction device can be configured as a chip connected to the central processing unit 9100, and the anisotropic medium crack prediction function can be realized through the control of the central processing unit.

[0173] like Fig.12 As shown, the electronic device 9600 may also include: a communication module 9110, an input unit 9120, an audio processor 9130, a display 9160, and a power supply 9170. It is worth noting that the electronic device 9600 does not necessarily have to include Fig.12 In addition, the electronic device 9600 may also include Fig.12 For components not shown, reference may be made to the prior art.

[0174] like Fig.12As shown, the central processing unit 9100 is sometimes also referred to as a controller or an operation control, and may include a microprocessor or other processor device and / or logic device. The central processing unit 9100 receives input and controls the operation of various components of the electronic device 9600.

[0175] The memory 9140 may be, for example, one or more of a cache, a flash memory, a hard drive, a removable medium, a volatile memory, a non-volatile memory or other suitable devices. The above-mentioned information related to the failure may be stored, and a program for executing the relevant information may also be stored. The CPU 9100 may execute the program stored in the memory 9140 to implement information storage or processing, etc.

[0176] The input unit 9120 provides input to the central processing unit 9100. The input unit 9120 is, for example, a key or a touch input device. The power supply 9170 is used to provide power to the electronic device 9600. The display 9160 is used to display display objects such as images and texts. The display may be, for example, an LCD display, but is not limited thereto.

[0177] The memory 9140 may be a solid-state memory, such as a read-only memory (ROM), a random access memory (RAM), a SIM card, etc. It may also be a memory that saves information even when the power is off, can be selectively erased, and is provided with more data, examples of which are sometimes referred to as EPROMs, etc. The memory 9140 may also be some other type of device. The memory 9140 includes a buffer memory 9141 (sometimes referred to as a buffer). The memory 9140 may include an application / function storage unit 9142, which is used to store application programs and function programs or processes for executing the operation of the electronic device 9600 through the central processor 9100.

[0178] The memory 9140 may also include a data storage unit 9143 for storing data, such as contacts, digital data, pictures, sounds, and / or any other data used by the electronic device. The driver storage unit 9144 of the memory 9140 may include various drivers for communication functions of the electronic device and / or for executing other functions of the electronic device (such as messaging applications, address book applications, etc.).

[0179] The communication module 9110 is a transmitter / receiver 9110 that sends and receives signals via an antenna 9111. The communication module (transmitter / receiver) 9110 is coupled to the central processor 9100 to provide input signals and receive output signals, which may be the same as the case of a conventional mobile communication terminal.

[0180] Based on different communication technologies, multiple communication modules 9110 may be provided in the same electronic device, such as a cellular network module, a Bluetooth module and / or a wireless LAN module, etc. The communication module (transmitter / receiver) 9110 is also coupled to a speaker 9131 and a microphone 9132 via an audio processor 9130 to provide an audio output via the speaker 9131 and receive an audio input from the microphone 9132, thereby realizing a common telecommunication function. The audio processor 9130 may include any suitable buffer, decoder, amplifier, etc. In addition, the audio processor 9130 is also coupled to the central processor 9100, so that recording can be performed on the local machine through the microphone 9132, and the sound stored on the local machine can be played through the speaker 9131.

[0181] The embodiments of the present application also provide a computer-readable storage medium capable of implementing all the steps of the anisotropic medium crack prediction method in the above embodiments. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, all the steps of the anisotropic medium crack prediction method in the above embodiments are implemented by the execution subject being a server or a client. For example, when the processor executes the computer program, the following steps are implemented:

[0182] Step 100: Determine the post-stack seismic traces corresponding to each azimuth based on the OVT wide-azimuth gather data of the target area.

[0183] It can be understood that the offset vector slice OVT technology is a processing method for wide-azimuth seismic data.

[0184] Step 200: According to the post-stack seismic traces corresponding to the respective azimuths, respectively determine the frequency gradient within a preset frequency range in each azimuth.

[0185] It is understandable that the stack migration section is migrated on the basis of the horizontal stack section. The original purpose of its development was to solve the problem of low lateral resolution caused by the spatial misalignment of the inclined reflection layer and the divergence of the diffraction wave in the horizontal stack section. According to the order of stacking and migration, the migration can be divided into pre-stack migration and post-stack migration. The stack migration section belongs to post-stack migration.

[0186] Step 300: performing ellipse fitting on the frequency spectrum gradients corresponding to the respective directions, and determining the anisotropic medium crack prediction result of the target area based on the corresponding fitting results.

[0187] From the above description, it can be seen that the computer-readable storage medium provided in the embodiment of the present application can effectively predict anisotropic medium fractures, and can effectively improve the processing efficiency, automation level and accuracy of the anisotropic medium fracture prediction process, and then can apply the anisotropic medium fracture prediction results to improve the interpretation accuracy and efficiency of fractured oil and gas reservoirs, and can effectively improve the accuracy and reliability of processing such as oil reservoir exploitation using the interpretation results of fractured oil and gas reservoirs, and effectively save manpower and material costs.

[0188] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, devices, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0189] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (apparatus), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0190] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0191] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0192] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for predicting cracks in anisotropic media, characterized in that: include: Determine the post-stack seismic traces corresponding to each azimuth based on the OVT wide-azimuth gather data in the target area; Determine the frequency spectrum gradient within a preset frequency range in each azimuth according to the post-stack seismic traces corresponding to each azimuth; Performing ellipse fitting on the frequency spectrum gradients corresponding to each of the directions, and determining the anisotropic medium crack prediction result of the target area based on the corresponding fitting results; The method of determining the post-stack seismic traces corresponding to each azimuth respectively based on the OVT wide azimuth gather data of the target area includes: Obtain OVT wide-azimuth gather data in the target area; Based on the polar coordinate symmetry of the anisotropic characteristics, the OVT wide azimuth gather data is divided into azimuth angles to obtain corresponding multiple azimuths; The OVT wide azimuth gather data are stacked according to the divided azimuths to form azimuth-divided post-stack seismic data composed of post-stack seismic traces corresponding to the azimuths; Determining the frequency spectrum gradient within a preset frequency range in each azimuth according to the post-stack seismic traces corresponding to each azimuth, respectively, includes: Performing Fourier transformation on the post-stack seismic traces corresponding to each of the azimuths to decompose them into frequency spectra of different frequencies; Selecting a spectrum whose spectrum value is greater than a frequency threshold from among the spectrums obtained by decomposition as a target spectrum; Determining a spectrum gradient within a preset frequency range in each of the directions based on the target spectrum; The Fourier transform is performed on the post-stack seismic traces corresponding to each of the azimuths to decompose them into frequency spectra of different frequencies, including: By specifying the window length, the short-time window Fourier transform is performed on the post-stack seismic data sequence of each azimuth to obtain the spectrum of different frequencies: The selecting a spectrum whose spectrum value is greater than a frequency threshold from each spectrum obtained by decomposition as a target spectrum, and determining a spectrum gradient within a preset frequency range in each of the directions based on the target spectrum, comprises: Count the spectrum values, find the frequency corresponding to the maximum spectrum position, and use this frequency as the starting frequency F start , the frequency corresponding to the spectrum value close to 0 is the end frequency F end , take the spectral values ​​from these spectral pairs and calculate their spectral gradients: In the formula, G represents the spectral gradient, S i represents the spectrum value corresponding to the i-th frequency, S i+1 represents the spectrum value corresponding to the i+1th frequency, and n represents the number of frequencies.

2. The anisotropic medium crack prediction method according to claim 1, characterized in that: The step of performing ellipse fitting on the frequency spectrum gradients corresponding to each of the directions comprises: Displaying the frequency spectrum gradients corresponding to each of the directions in polar coordinates; Perform ellipse fitting on the frequency spectrum gradients corresponding to each of the orientations according to the polar coordinate display results to obtain corresponding fitting results; The fitting result includes the major axis length, minor axis length and major axis orientation of the ellipse.

3. The anisotropic medium crack prediction method according to claim 2, characterized in that: The step of determining the anisotropic medium fracture prediction result of the target area based on the corresponding fitting result includes: The orientation of the major axis of the ellipse is used as the crack direction of the anisotropic medium; Determining the fracture strength of the anisotropic medium according to the ratio of the major axis length to the minor axis length of the ellipse; The anisotropic medium fracture prediction result including the fracture direction and fracture strength is output.

4. The anisotropic medium crack prediction method according to claim 3, characterized in that: The output includes the anisotropic medium fracture prediction result including the fracture direction and fracture strength, including: Determining whether the crack strength is equal to or greater than a strength threshold, and if so, determining that the anisotropic medium has crack characteristics; The anisotropic medium fracture prediction result is output, wherein the anisotropic medium fracture prediction result includes fracture direction, fracture strength and information for indicating the existence of fracture characteristics in the anisotropic medium.

5. A device for predicting cracks in anisotropic media, characterized in that: include: The post-stack seismic trace determination module is used to determine the post-stack seismic traces corresponding to each azimuth based on the OVT wide-azimuth gather data of the target area; A spectrum gradient determination module, used to determine the spectrum gradient within a preset frequency range in each azimuth according to the post-stack seismic traces corresponding to each of the azimuths; A crack prediction module, used for performing ellipse fitting on the frequency spectrum gradients corresponding to each of the orientations, and determining the anisotropic medium crack prediction result of the target area based on the corresponding fitting result; The post-stack seismic trace determination module is used to perform the following: Obtain OVT wide-azimuth gather data in the target area; Based on the polar coordinate symmetry of the anisotropic characteristics, the OVT wide azimuth gather data is divided into azimuth angles to obtain corresponding multiple azimuths; The OVT wide azimuth gather data are stacked according to the divided azimuths to form azimuth-divided post-stack seismic data composed of post-stack seismic traces corresponding to the azimuths; The spectrum gradient determination module is used to perform the following: Performing Fourier transformation on the post-stack seismic traces corresponding to each of the azimuths to decompose them into frequency spectra of different frequencies; Selecting a spectrum whose spectrum value is greater than a frequency threshold from among the spectrums obtained by decomposition as a target spectrum; Determining a spectrum gradient within a preset frequency range in each of the directions based on the target spectrum; The Fourier transform is performed on the post-stack seismic traces corresponding to each of the azimuths to decompose them into frequency spectra of different frequencies, including: By specifying the window length, the short-time window Fourier transform is performed on the post-stack seismic data sequence of each azimuth to obtain the spectrum of different frequencies: The selecting a spectrum whose spectrum value is greater than a frequency threshold from each spectrum obtained by decomposition as a target spectrum, and determining a spectrum gradient within a preset frequency range in each of the directions based on the target spectrum, comprises: Count the spectrum values, find the frequency corresponding to the maximum spectrum position, and use this frequency as the starting frequency F start , the frequency corresponding to the spectrum value close to 0 is the end frequency F end , take the spectral values ​​from these spectral pairs and calculate their spectral gradients: In the formula, G represents the spectral gradient, S i represents the spectrum value corresponding to the i-th frequency, S i+1 represents the spectrum value corresponding to the i+1th frequency, and n represents the number of frequencies.

6. The anisotropic medium crack prediction device according to claim 5, characterized in that: The crack prediction module comprises: Ellipse fitting unit, used to perform the following: Displaying the frequency spectrum gradients corresponding to each of the directions in polar coordinates; Perform ellipse fitting on the frequency spectrum gradients corresponding to each of the orientations according to the polar coordinate display results to obtain corresponding fitting results; The fitting result includes the major axis length, minor axis length and major axis orientation of the ellipse.

7. The anisotropic medium crack prediction device according to claim 6, characterized in that: The crack prediction module further includes: A direction determination unit, used for taking the orientation of the major axis of the ellipse as the crack direction of the anisotropic medium; A strength determination unit, configured to determine the fracture strength of the anisotropic medium according to a ratio of a major axis length to a minor axis length of the ellipse; The result output unit is used to output the anisotropic medium fracture prediction result including the fracture direction and fracture strength.

8. The anisotropic medium crack prediction device according to claim 7, characterized in that: The result output unit is used to perform the following: Determining whether the crack strength is equal to or greater than a strength threshold, and if so, determining that the anisotropic medium has crack characteristics; The anisotropic medium fracture prediction result is output, wherein the anisotropic medium fracture prediction result includes fracture direction, fracture strength and information for indicating the existence of fracture characteristics in the anisotropic medium.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the anisotropic medium crack prediction method according to any one of claims 1 to 4 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the anisotropic medium crack prediction method according to any one of claims 1 to 4 is implemented.

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