Method for calculating fitting degree of pre-stack amplitude preservation evaluation parameter AVO of seismic data

Abstract

The invention belongs to the technical field of geophysics, and particularly relates to a seismic data pre-stack amplitude preservation evaluation parameter AVO fitting degree calculation method, which comprises the following steps: firstly generating a well-side theoretical CRP gather, then processing seismic data, generating a well-side actual CRP gather, and finally carrying out AVO fitting degree calculation. According to the method, the AVO fitting degree is expressed through the overall fitting degree of the elastic parameter actual value and the theoretical value corresponding to the well-side CRP gather, the pre-stack amplitude preservation performance of the well-side actual CRP gather is reflected, the calculated AVO fitting degree result has practical significance on seismic data processing, the amplitude preservation performance of actual pre-stack seismic data can be visually and quantitatively analyzed, and the method has the advantages of being high in practicability and the like. Parameter evaluation of a processing link and amplitude preservation monitoring of a processing flow are facilitated, and the method is of great significance to investigation of pre-stack amplitude preservation of seismic data.

Description

Technical Field

[0001] The invention belongs to the field of geophysical technology, and particularly relates to a method for calculating the AVO fitting degree of a pre-stack amplitude preservation evaluation parameter of seismic data. Background Art

[0002] With the gradual deepening of oil and gas exploration, it is becoming more and more important to find lithologic oil and gas reservoirs, which puts higher requirements on the amplitude preservation of seismic data processing. Amplitude preservation refers to making the relative relationship of the peak amplitude of seismic data reflect the relative relationship of the formation reflection coefficient as realistically as possible through the processing link. At present, the amplitude preservation analysis methods of seismic data proposed by various scholars can be roughly divided into two categories. One is the conventional analysis method in processing, which only uses the seismic data itself during analysis, such as residual analysis method, time-frequency analysis method, amplitude curve comparison method, amplitude ratio calculation method, wavelet consistency analysis method, layer-by-layer seismic attribute analysis method, slice analysis method, etc. The judgment of amplitude preservation in this type of method relies on processing experience, and it is difficult to intuitively understand the relative relationship of the real reflection coefficient; the other is the integrated processing and interpretation method, such as synthetic recording method, AVO attribute analysis method, etc., which uses a variety of data such as seismic and well logging in the analysis. The theoretical reflection coefficient of the formation is calculated and the theoretical seismic data is synthesized during the analysis process. Through comparison, the amplitude preservation of the actual seismic data can be intuitively analyzed.

[0003] AVO (Amplitude Variation with Offset / Amplitude Versus Offset) is a seismic exploration technology that uses the characteristics of amplitude variation with shot offset to analyze and identify lithology and oil and gas reservoirs. Some scholars have conducted research on AVO attribute analysis, but most of them remain at the qualitative comparison of the relationship between the amplitude variation of theoretical and actual gathers. A few scholars have quantitatively calculated and compared some elastic parameters through curve fitting, but their parameter settings lack practical significance for seismic data processing and are not convenient for the evaluation and monitoring of processing links and processes. Summary of the invention

[0004] In view of the above problems, on the one hand, the present invention proposes a method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data, comprising the following steps:

[0005] Post-stack calibration of actual wellside traces and theoretical traces to obtain calibrated first information, and pre-stack calibration combined with the first information to generate wellside theoretical CRP trace gathers;

[0006] Acquire the actual CRP gathers near the well, and determine whether the actual CRP gathers near the well meet the basic standard of amplitude preservation. If the actual CRP gathers near the well do not meet the basic standard of amplitude preservation, process the seismic data, and obtain the processing results of the seismic data to generate the actual CRP gathers near the well;

[0007] The AVO fitting degree is calculated based on the theoretical CRP gathers near the well and the actual CRP gathers near the well.

[0008] Furthermore, the post-stack calibration of the actual wellside trace and the theoretical trace to obtain the calibrated first information includes the following steps:

[0009] Identify the target layer and calculate the theoretical post-stack reflection coefficient according to the well logging curve; the well logging curve includes the well logging density and the acoustic wave curve;

[0010] According to the theoretical post-stack reflection coefficient and using seismic wavelet and logging time-depth relationship, a time-shift domain wellside theoretical trace is synthesized;

[0011] The wave group waveforms of the actual wellside trace in the time migration domain and the theoretical wellside trace in the time migration domain are compared, and the seismic wavelet and the logging time-depth relationship are adjusted according to the comparison results. When the actual wellside trace in the time migration domain and the theoretical wellside trace in the time migration domain are most consistent, the post-stack calibration is completed to obtain the first information after calibration.

[0012] Further, performing pre-stack calibration in combination with the first information and generating a wellside theoretical CRP gather comprises the following steps:

[0013] The pre-stack reflection coefficient that varies with the reflection angle is calculated based on the second information theory, and the theoretical CRP angle gathers beside the well in the time migration domain are synthesized;

[0014] The theoretical CRP angle gathers beside the well in the time offset domain are converted into offset gathers, the seismic wavelet and the time-depth relationship of the logging are adjusted, and the calibration is completed when the actual CRP gathers beside the well are consistent with the theoretical CRP gathers to generate the theoretical CRP gathers beside the well.

[0015] Further, the second information includes the first information, actual CRP gathers beside the well in the time migration domain, layer velocity in the time migration domain, well logging density, acoustic wave and shear wave curves;

[0016] The first information includes the seismic wavelet obtained by post-stack calibration and the time-depth relationship of well logging.

[0017] Furthermore, if the actual CRP gathers obtained near the well meet the basic standards for amplitude preservation, they are used directly;

[0018] The basic amplitude preservation standard is that the actual CRP gathers near the well have been subjected to inverse geometric diffusion compensation and amplitude-preserving prestack time migration.

[0019] Furthermore, the process of obtaining the seismic data processing results to generate the actual CRP gathers near the well includes the following steps:

[0020] Obtain processed seismic data information, including shot gathers, detector domain gathers, shot-detection line cross-domain gathers or CMP gathers;

[0021] Sorting CMP gathers: sorting the gathers obtained from other domains into CMP gathers;

[0022] If the CMP gather has been subjected to geometric diffusion compensation, then the CMP gather is subjected to inverse geometric diffusion compensation;

[0023] According to the CMP gathers after inverse geometric diffusion compensation and the time migration velocity field, the amplitude-preserving migration is performed with given migration parameters, and the actual CRP gathers near the well are obtained by migration.

[0024] Further, the compensation parameters used for performing inverse geometric diffusion compensation on the CMP gather are the same as the geometric diffusion compensation parameters of the CMP gather in the historical processing record;

[0025] The migration parameters include a given migration aperture, a migration tilt angle, an anti-aliasing factor and a migration range.

[0026] Further, calculating the AVO fit according to the wellside theoretical CRP gather and the wellside actual CRP gather comprises the following steps:

[0027] Converting the wellside CRP gathers from the offset domain to the angle domain, wherein the wellside CRP gathers include the wellside theoretical CRP gathers and the wellside actual CRP gathers;

[0028] Read the amplitude values ​​corresponding to different reflection angles at the time position of the target layer on the wellside CRP gather in the angle domain;

[0029] Determine fitting parameters, and construct a fitting model between the amplitude value and the reflection angle according to the fitting parameters, and convert the fitting model into an objective function; the fitting parameters include a longitudinal wave reflection coefficient, a shear wave reflection coefficient and a density reflection coefficient;

[0030] The elastic parameter harmonic error and the AVO fitting degree are calculated according to the fitting parameters.

[0031] Furthermore, the conversion of the wellside CRP gather from the offset domain to the angle domain is specifically as follows:

[0032] The wellside CRP gathers in the time migration domain and the interval velocity in the time migration domain are input, and a specific conversion method is used to convert the wellside CRP gathers from the offset domain to the angle domain.

[0033] Furthermore, the fitting model between the amplitude value and the reflection angle is as follows:

[0034]

[0035] Among them, R pp (θ) is the longitudinal wave reflection coefficient that changes with the reflection angle, θ is the reflection angle; R pis the longitudinal wave reflection coefficient; R s is the shear wave reflection coefficient; R ρ is the density reflection coefficient; is the ratio of transverse and longitudinal wave velocities;

[0036] The objective function is as follows:

[0037] J(R p ,R s ,R ρ )=||R pp -R pp (R p ,R s ,R ρ )|| 2

[0038] Among them, J(R p ,R s ,R ρ ) is the objective function, R pp is the measured value, R pp (R p ,R s ,R ρ ) is the fitted value.

[0039] Further, calculating the elastic parameter harmonic error and the AVO fitting degree according to the fitting parameters includes the following steps:

[0040] Calculate the percentage error of the longitudinal wave reflection coefficient separately Shear wave reflection coefficient percentage error And the density reflectance percentage error

[0041] Percent error according to longitudinal wave reflection coefficient Shear wave reflection coefficient percentage error And the density reflectance percentage error Calculate the elastic parameter harmonic error Berr;

[0042] The AVO goodness of fit is calculated based on the harmonic errors of the elastic parameters.

[0043] Furthermore, the longitudinal wave reflection coefficient percentage error The calculation formula is as follows:

[0044]

[0045] The shear wave reflection coefficient percentage error The calculation formula is as follows:

[0046]

[0047] The density reflectance percentage error The calculation formula is as follows:

[0048]

[0049] in, are the theoretical values ​​of longitudinal wave reflection coefficient, shear wave reflection coefficient and density reflection coefficient, respectively. are the actual values ​​of longitudinal wave reflection coefficient, shear wave reflection coefficient and density reflection coefficient respectively;

[0050] The calculation formula of the elastic parameter harmonic error Berr is as follows:

[0051]

[0052] Among them, a, b, and 1-ab are the importance of the longitudinal wave reflection coefficient, the shear wave reflection coefficient, and the density reflection coefficient, respectively, and all of them are greater than or equal to zero;

[0053] The calculation formula of the AVO goodness of fit is as follows:

[0054] P match =(1-Berr)×100%

[0055] Where P match is the AVO fitting degree, which indicates the overall fitting degree between the actual value of the elastic parameter corresponding to the CRP gather near the well and the theoretical value.

[0056] In a second aspect, the present invention proposes a calculation system for the AVO fitting degree of a pre-stack amplitude preservation evaluation parameter of seismic data, comprising:

[0057] A wellside theoretical CRP gather generating unit is used for post-stack calibration of the wellside actual and theoretical traces to obtain the calibrated first information, and performs pre-stack calibration in combination with the first information to generate the wellside theoretical CRP gather;

[0058] A wellside actual CRP gather generating unit is used to obtain the wellside actual CRP gather and determine whether the wellside actual CRP gather meets the basic standard of amplitude preservation. If the wellside actual CRP gather does not meet the basic standard of amplitude preservation, the seismic data is processed and the seismic data processing result is obtained to generate the wellside actual CRP gather;

[0059] The calculation unit is used to calculate the AVO fit according to the theoretical CRP gathers near the well and the actual CRP gathers near the well.

[0060] In a third aspect, the present invention provides an electronic device, comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus;

[0061] a memory storing a computer program;

[0062] The processor is used to implement the calculation method of the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data when executing the program stored in the memory.

[0063] In a fourth aspect, the present invention proposes a computer-readable storage medium storing a computer program, which, when executed, executes the method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data.

[0064] Beneficial effects of the present invention:

[0065] The present invention proposes a calculation method for the AVO fitting degree of a pre-stack amplitude preservation evaluation parameter of seismic data, which first generates a theoretical CRP gather near a well, then processes the seismic data to generate an actual CRP gather near a well, and finally calculates the AVO fitting degree. The present invention represents the AVO fitting degree by the overall fitting degree between the actual value of the elastic parameter corresponding to the CRP gather near the well and the theoretical value, reflecting the pre-stack amplitude preservation of the actual CRP gather near the well. The calculated AVO fitting degree result has practical significance for seismic data processing, can intuitively and quantitatively analyze the amplitude preservation of actual pre-stack seismic data, is convenient for parameter evaluation in a processing link and amplitude preservation monitoring in a processing flow, and is of great significance for investigating the pre-stack amplitude preservation of seismic data.

[0066] The present invention uses inverse geometric diffusion compensation and amplitude-preserving prestack time migration in the process of generating the actual CRP gathers near the well, thereby ensuring the accuracy of the gathers; and uses the Aki-Richard approximate formula to fit, calculate the elastic parameter harmonic error and the AVO fit in the process of performing the AVO fit calculation, thereby ensuring the practical significance and intuitiveness of the parameter setting.

[0067] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0069] Figure 1A flow chart of a method for calculating the AVO fitting degree of a pre-stack amplitude preservation evaluation parameter of seismic data proposed in an embodiment of the present invention is shown;

[0070] Figure 2 A schematic diagram of actual and theoretical wellside traces for post-stack calibration in an embodiment of the present invention is shown;

[0071] Figure 3 A schematic diagram of pre-stack calibration and generation of wellside theoretical CRP gathers in an embodiment of the present invention is shown;

[0072] Figure 4 It shows a schematic diagram of converting a wellside CRP gather into an angle domain in an embodiment of the present invention;

[0073] Figure 5 The figure shows the fitting result using the Aki-Richard approximation formula in the embodiment of the present invention;

[0074] Figure 6 A schematic diagram of the architecture of a calculation system for the AVO fitting degree of a pre-stack amplitude preservation evaluation parameter of seismic data in an embodiment of the present invention is shown;

[0075] Figure 7 The schematic diagram of the architecture of the electronic device for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data proposed in the embodiment of the present invention is shown. DETAILED DESCRIPTION

[0076] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0077] The purpose of the present invention is to propose a pre-stack amplitude preservation evaluation parameter AVO fitting degree and a calculation method thereof. The AVO fitting degree has practical significance for seismic data processing, can intuitively and quantitatively analyze the amplitude preservation of actual pre-stack seismic data, and is convenient for parameter evaluation in the processing link and monitoring of the processing flow.

[0078] The AVO fit is the degree of fit between the actual AVO and the theoretical AVO, which refers to the degree of fit between the amplitude curves of the actual common reflection point gathers near the well and the theoretical common reflection point gathers at the geological interface of the target layer with the change of offset (or angle). The higher the AVO fit, the better the amplitude preservation of the prestack seismic data. Therefore, this parameter can be used to evaluate the amplitude preservation of different processing parameters in the same processing link, and can also be used to monitor the amplitude preservation of the entire processing flow.

[0079] The AVO goodness of fit calculation method is as follows: Figure 1 As shown, the following steps are included:

[0080] S1: Post-stack calibration of actual wellside traces and theoretical traces to obtain first calibrated information, and pre-stack calibration combined with the first information to generate wellside theoretical CRP trace gathers;

[0081] CRP gathers (common reflection point gathers), in seismic data acquisition, when the reflection interface is horizontal, different traces can always be found in different common shot point gathers on the survey line. When some traces come from a common point on the underground interface, this point is called a common reflection point, and the corresponding recording traces of the common reflection point constitute a common reflection point gather.

[0082] Generating the wellside theoretical CRP gather in step S1 includes the following steps:

[0083] The first information after calibration is obtained by post-stack calibration of the actual well track and the theoretical track, which is:

[0084] Define the target layer, input the well logging density, acoustic wave curve, etc., calculate the theoretical post-stack reflection coefficient, give the seismic wavelet and well logging time-depth relationship, and synthesize the theoretical well track in the time offset domain;

[0085] The wave group waveforms of the actual wellside trace in the time offset domain and the theoretical wellside trace in the time offset domain are compared, and the seismic wavelet and the logging time-depth relationship are adjusted. When the actual wellside trace in the time offset domain and the theoretical wellside trace in the time offset domain are most consistent, the calibration is completed, and the first information after calibration is obtained, that is, the seismic wavelet and the logging time-depth relationship at this time.

[0086] Combined with the first information, pre-stack calibration is performed and a wellside theoretical CRP gather is generated, specifically:

[0087] Input the seismic wavelet obtained by post-stack calibration, the time-depth relationship of well logging, the actual CRP gathers beside the well in the time migration domain, the layer velocity, well logging density, acoustic wave and shear wave curves in the time migration domain, etc., calculate the theoretical pre-stack reflection coefficient that changes with the reflection angle, and synthesize the theoretical CRP angle gathers beside the well in the time migration domain;

[0088] The theoretical CRP angle gathers beside the well in the time offset domain are converted into offset gathers, and the seismic wavelet and the time-depth relationship of the logging are fine-tuned. When the actual CRP gathers beside the well are consistent with the theoretical CRP gathers, the calibration is completed to obtain the theoretical CRP gathers beside the well.

[0089] Prestack calibration uses unstacked seismic data, which contains more frequency information and has better resolution. Prestack inversion uses prestack CRP gather data (or partially stacked data), velocity data (generally offset velocity) and well data (S-wave velocity, P-wave velocity, density and other elastic parameter data) to obtain various elastic parameters related to lithology and hydrocarbon content by using different approximate inversion solutions, and further use them to predict reservoir lithology, reservoir physical properties and hydrocarbon content. Poststack inversion, also known as wave impedance inversion, refers to the use of offset and stacked seismic data to invert the formation acoustic impedance (or velocity) to predict reservoirs.

[0090] S2: obtaining an actual CRP gather near the well, and determining whether the actual CRP gather near the well meets the basic standard for amplitude preservation; if the actual CRP gather near the well does not meet the basic standard for amplitude preservation, processing the seismic data, and obtaining the processing result of the seismic data to generate the actual CRP gather near the well;

[0091] If the actual CRP gathers obtained near the well meet the basic standards for amplitude preservation, they can be used directly.

[0092] The basic amplitude preservation standard is that the actual CRP gathers near the well have been processed with inverse geometric diffusion compensation and amplitude-preserving prestack time migration.

[0093] Seismic data processing includes completing a processing link in the middle of seismic data or completing a parameter test in a specific link; specifically, seismic data processing links include denoising, amplitude compensation and other links. Using one of the links, such as the denoised data, to calculate the AVO fit is a link. When a link, such as selecting a specific denoising method for denoising, there are also different denoising parameter tests. One parameter corresponds to a test data result, and the AVO fit is calculated based on the specific test data result.

[0094] Obtaining the seismic data processing results to generate the actual CRP gathers near the well specifically includes the following steps:

[0095] Obtain the processing results of seismic data. The obtained processing results of seismic data may be shot gathers, detector domain gathers, shot detection line cross domain gathers or CMP gathers, etc. CMP gathers (Common Middle Point) refer to extracting the gathers with common middle points from different shot gathers to form a new set.

[0096] Sorting CMP gathers: sorting the gathers obtained from other domains into CMP gathers;

[0097] Inverse geometric diffusion compensation: In this process, if geometric diffusion compensation has been performed in the historical processing records of the CMP gather, then inverse geometric diffusion compensation is required, and the parameters used are the same as those in the historical processing records; if the CMP gather has not been subjected to geometric diffusion compensation, then directly proceed to the next step;

[0098] Perform amplitude-preserving prestack time migration. In this process, the CMP gathers and time migration velocity field are input, and parameters such as migration aperture, migration inclination, anti-aliasing factor, and migration range are given. The mainstream amplitude-preserving migration method is used to migrate and obtain the actual CRP gathers near the well.

[0099] S3: Calculating the AVO fit according to the wellside theoretical CRP gather and the wellside actual CRP gather, specifically including the following steps:

[0100] Convert the wellside CRP gathers to the angle domain. In this process, the wellside CRP gathers in the time offset domain and the layer velocity in the time offset domain are input, and the wellside CRP gathers are converted from the offset domain to the angle domain using the mainstream conversion method; the wellside CRP gathers include the wellside theoretical CRP gathers and the wellside actual CRP gathers;

[0101] In one embodiment of the present invention, for example, the following conversion formula may be used to convert the wellside CRP gather from the offset domain to the angle domain:

[0102] z=z(t)

[0103]

[0104]

[0105] Where t represents the reflection time of each point on the reflected wave, v t and v 0 They represent the initial velocity and final velocity of each point on the reflected wave, θ represents the reflection angle, Δx represents the horizontal offset, and z t and z 0 They represent the end displacement and initial displacement of each point on the reflected wave respectively.

[0106] Read the amplitude values ​​corresponding to different reflection angles at the time position of the target layer on the wellside CRP gather in the angle domain;

[0107] The amplitude value read as the reflection angle changes is fitted using the Aki-Richard approximate formula, which is:

[0108]

[0109] Among them, R pp(θ) is the longitudinal wave reflection coefficient that varies with the reflection angle, and θ is the reflection angle; is the longitudinal wave reflection coefficient; is the shear wave reflection coefficient; is the density reflection coefficient; is the ratio of transverse and longitudinal wave velocities;

[0110] in,

[0111] ΔVp=Vp2-Vp1, Vp1 and Vp2 represent the longitudinal wave velocities of different media, respectively;

[0112] ΔVs=Vs2-Vs1, Vs1 and Vs2 represent the shear wave velocities of different media, respectively;

[0113] Δρ=ρ2-ρ1, ρ1 and ρ2 represent the densities of different media respectively;

[0114] Given by the prior information logging curve The fitting problem of the reflection coefficient that varies with angle can be expressed as:

[0115] J(R p ,R s ,R ρ )=||R pp -R pp (R p ,R s ,R ρ )|| 2 (2)

[0116] Among them, J(R p ,R s ,R ρ ) is the objective function, R pp is the measured value, R pp (R p ,R s ,R ρ ) is the fitting value. The best fitting problem refers to finding R p , R s and R ρ To minimize the objective function value, assuming that the reflection coefficient can be replaced by the amplitude value, when the amplitude values ​​at different angles are known, the R corresponding to the best fit is obtained by solving the linear equation p , R s and R ρ , use the above method to obtain the R corresponding to the actual CRP gathers near the well and the theoretical CRP gathers respectively p , R s and R ρIt should be noted that since the amplitude value is used instead of the reflection coefficient, the R p , R s and R ρ It is not a true elastic parameter, but it does not affect the subsequent definition and calculation of AVO fit.

[0117] According to R p , R s and R ρ Calculate the elastic parameter harmonic error and AVO fit; specifically include the following steps:

[0118] ① Calculate the percentage error of the longitudinal wave reflection coefficient respectively Shear wave reflection coefficient percentage error And the density reflectance percentage error The three methods evaluate the errors between actual and theoretical values ​​of different elastic parameters corresponding to the CRP gathers near the well;

[0119] The calculation formula is as follows:

[0120]

[0121] in, are the theoretical values ​​of longitudinal wave reflection coefficient, shear wave reflection coefficient and density reflection coefficient, respectively. are the actual values ​​of longitudinal wave reflection coefficient, shear wave reflection coefficient and density reflection coefficient respectively;

[0122] ②According to the percentage error of longitudinal wave reflection coefficient Shear wave reflection coefficient percentage error And the density reflectance percentage error Calculate the elastic parameter harmonic error Berr;

[0123] The calculation formula is as follows:

[0124]

[0125] Among them, a, b, 1-ab are p , R s , R ρ The importance of the inspection, all three are greater than or equal to zero, and can be given according to different inspection situations. In one embodiment of the present invention, a, b, 1-ab are all set to

[0126] ③ Calculate the AVO fitting degree P according to the elastic parameter harmonic error match , the calculation formula is as follows:

[0127] P match =(1-Berr)×100% (5)

[0128] Among them, P match is the AVO fitting degree, which indicates the overall fitting degree between the actual value of the elastic parameter corresponding to the CRP gather near the well and the theoretical value, and reflects the pre-stack amplitude preservation of the actual CRP gather near the well. Obviously, the higher the AVO fitting degree, the better the pre-stack amplitude preservation of the actual CRP gather near the well.

[0129] In an exemplary embodiment of the present invention, step S1 is performed according to the above method. First, the actual well track and the theoretical track are calibrated after stacking. The calibration result is as follows: Figure 2 Then, pre-stack calibration is performed to generate the theoretical CRP gathers near the well. The synthesized CRP gathers are shown in Figure 3 As shown;

[0130] In the seismic data processing link of step S2, the CMP gathers that have completed the preliminary processing are used. Since the CMP gathers that have completed the preliminary processing are used in this embodiment, there is no need to sort the CMP gathers. Inverse geometric diffusion compensation is directly performed. Here, the original CMP gathers have undergone geometric diffusion compensation, and inverse geometric diffusion compensation is required here. Finally, amplitude-preserving prestack time migration is performed. In this process, the CMP gathers and time migration velocity fields are input, and parameters such as the migration aperture, migration inclination, anti-aliasing factor, and migration range are given. The mainstream amplitude-preserving migration method is used to migrate the actual CRP gathers near the well.

[0131] In step S3, the AVO fit calculation is performed. First, the wellside CRP gathers are converted into the angle domain, such as Figure 4 Secondly, extract the amplitude value at the geological interface of the target layer. In this process, read the amplitude values ​​corresponding to different reflection angles at the time position of the target layer on the wellside CRP gather in the angle domain, as shown in Figure 2. Figure 4 The dashed box indicated by the arrow in the right figure. Then, the Aki-Richard approximate formula is used for fitting. In this process, the amplitude value read with the reflection angle is fitted using the Aki-Richard approximate formula. The theoretical CRP gathers near the well and the actual CRP gathers are fitted respectively, and the fitting curve of the theoretical CRP gathers near the well, the amplitude of the actual CRP gathers near the well, and the fitting curve of the actual CRP gathers near the well are displayed, as shown in Figure 1. Figure 5 Finally, the elastic parameter harmonic error and AVO fitting degree are calculated. The calculation results are shown in Table 1, which shows that the AVO fitting degree of the actual wellside CRP gather is 56%.

[0132] Table 1

[0133]

[0134] Based on the same concept of the present invention, another exemplary embodiment of the present invention provides a calculation system for the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data, such as Figure 6 As shown, including:

[0135] The wellside theoretical CRP gather generating unit 601 is used for post-stack calibration of the wellside actual and theoretical traces to obtain the calibrated first information, and performs pre-stack calibration in combination with the first information to generate the wellside theoretical CRP gather;

[0136] The actual CRP gathers beside the well generating unit 602 is used to obtain the actual CRP gathers beside the well, and determine whether the actual CRP gathers beside the well meet the basic standard of amplitude preservation. If the actual CRP gathers beside the well do not meet the basic standard of amplitude preservation, the seismic data are processed, and the seismic data processing results are obtained to generate the actual CRP gathers beside the well;

[0137] The calculation unit 603 is used to calculate the AVO fit according to the theoretical CRP gathers near the well and the actual CRP gathers near the well.

[0138] Based on the same inventive concept, another exemplary embodiment of the present invention provides an electronic device. Figure 7 As shown, the electronic device includes at least one processor 701, at least one communication interface 702, at least one memory 703 and at least one communication bus 704; wherein the processor 701, the communication interface 702 and the memory 703 communicate with each other through the communication bus 704;

[0139] Memory 703, storing computer programs;

[0140] The processor 701 is used to implement the calculation method of the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data when executing the program stored in the memory 703.

[0141] Optionally, the communication interface may be an interface of a communication module, such as an interface of a GSM module; the processor may be a processor CPU, or an application specific integrated circuit ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present invention. The memory may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory. The memory stores a program, and the processor calls the program stored in the memory to execute some or all of the above method embodiments.

[0142] Based on the same inventive concept, the embodiment of the present application further provides a computer-readable storage medium storing a computer program, which implements part or all of the above method embodiments when the computer program is executed. Optionally, the storage medium may be a non-temporary computer-readable storage medium, for example, the non-temporary computer-readable storage medium may be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

[0143] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data, characterized in that: The following steps are involved: Post-stack calibration of actual wellside traces and theoretical traces to obtain calibrated first information, and pre-stack calibration combined with the first information to generate wellside theoretical CRP trace gathers; Acquire the actual CRP gathers near the well, and determine whether the actual CRP gathers near the well meet the basic standard of amplitude preservation. If the actual CRP gathers near the well do not meet the basic standard of amplitude preservation, process the seismic data, and obtain the processing results of the seismic data to generate the actual CRP gathers near the well; The AVO fitting degree is calculated based on the theoretical CRP gathers near the well and the actual CRP gathers near the well.

2. The method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to claim 1 is characterized in that: The post-stack calibration of the actual wellside trace and the theoretical trace to obtain the calibrated first information comprises the following steps: Identify the target layer and calculate the theoretical post-stack reflection coefficient according to the well logging curve; the well logging curve includes the well logging density and the acoustic wave curve; According to the theoretical post-stack reflection coefficient and using seismic wavelet and logging time-depth relationship, a time-shift domain wellside theoretical trace is synthesized; The wave group waveforms of the actual wellside trace in the time migration domain and the theoretical wellside trace in the time migration domain are compared, and the seismic wavelet and the logging time-depth relationship are adjusted according to the comparison results. When the actual wellside trace in the time migration domain and the theoretical wellside trace in the time migration domain are most consistent, the post-stack calibration is completed to obtain the first information after calibration.

3. The method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to claim 1, characterized in that: Combining the first information with the pre-stack calibration to generate a wellside theoretical CRP gather comprises the following steps: The pre-stack reflection coefficient that varies with the reflection angle is calculated based on the second information theory, and the theoretical CRP angle gathers beside the well in the time migration domain are synthesized; The theoretical CRP angle gathers beside the well in the time offset domain are converted into offset gathers, the seismic wavelet and the time-depth relationship of the logging are adjusted, and the calibration is completed when the actual CRP gathers beside the well are consistent with the theoretical CRP gathers to generate the theoretical CRP gathers beside the well.

4. The method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to claim 3 is characterized in that: The second information includes the first information, actual CRP gathers beside the well in the time migration domain, layer velocity in the time migration domain, well logging density, sonic wave and shear wave curves; The first information includes the seismic wavelet obtained by post-stack calibration and the time-depth relationship of well logging.

5. The method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to claim 1, characterized in that: If the actual CRP gathers near the well meet the basic standards for amplitude preservation, they will be used directly; The basic amplitude preservation standard is that the actual CRP gathers near the well have been subjected to inverse geometric diffusion compensation and amplitude-preserving prestack time migration.

6. The method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to claim 1, characterized in that: The method of obtaining the seismic data processing results to generate the actual CRP gathers near the well comprises the following steps: Obtain processed seismic data information, including shot gathers, detector domain gathers, shot-detection line cross-domain gathers or CMP gathers; Sorting CMP gathers: sorting the gathers obtained from other domains into CMP gathers; If the CMP gather has been subjected to geometric diffusion compensation, then the CMP gather is subjected to inverse geometric diffusion compensation; According to the CMP gathers after inverse geometric diffusion compensation and the time migration velocity field, the amplitude-preserving migration is performed with given migration parameters, and the actual CRP gathers near the well are obtained by migration.

7. The method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to claim 6, characterized in that: The compensation parameters used for performing inverse geometric diffusion compensation on the CMP gather are the same as the geometric diffusion compensation parameters of the CMP gather in the historical processing record; The migration parameters include a given migration aperture, a migration tilt angle, an anti-aliasing factor and a migration range.

8. The method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to claim 6, characterized in that: Calculating the AVO fit based on the wellside theoretical CRP gather and the wellside actual CRP gather includes the following steps: Converting the wellside CRP gathers from the offset domain to the angle domain, wherein the wellside CRP gathers include the wellside theoretical CRP gathers and the wellside actual CRP gathers; Read the amplitude values ​​corresponding to different reflection angles at the time position of the target layer on the wellside CRP gather in the angle domain; Determine fitting parameters, and construct a fitting model between the amplitude value and the reflection angle according to the fitting parameters, and convert the fitting model into an objective function; the fitting parameters include a longitudinal wave reflection coefficient, a shear wave reflection coefficient and a density reflection coefficient; The elastic parameter harmonic error and the AVO fitting degree are calculated according to the fitting parameters.

9. The method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to claim 8, characterized in that: The conversion of the wellside CRP gather from the offset domain to the angle domain is specifically as follows: The wellside CRP gathers in the time migration domain and the interval velocity in the time migration domain are input, and a specific conversion method is used to convert the wellside CRP gathers from the offset domain to the angle domain.

10. The method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to claim 8, characterized in that: The fitting model between the amplitude value and the reflection angle is as follows: Among them, R pp (θ) is the longitudinal wave reflection coefficient that changes with the reflection angle, θ is the reflection angle; R p is the longitudinal wave reflection coefficient; R s is the shear wave reflection coefficient; R ρ is the density reflection coefficient; is the ratio of transverse and longitudinal wave velocities; The objective function is as follows: J(R p ,R s ,R ρ )=||R pp -R pp (R p ,R s ,R ρ )||2 Among them, J(R p ,R s ,R ρ ) is the objective function, R pp is the measured value, R pp (R p ,R s ,R ρ ) is the fitted value.

11. The method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to claim 8, characterized in that: Calculating the elastic parameter harmonic error and AVO fitting degree according to the fitting parameters includes the following steps: Calculate the percentage error of the longitudinal wave reflection coefficient separately Shear wave reflection coefficient percentage error And the density reflectance percentage error According to the percentage error of longitudinal wave reflection coefficient Shear wave reflection coefficient percentage error And the density reflectance percentage error Calculate the elastic parameter harmonic error Berr; The AVO goodness of fit is calculated based on the elastic parameters and the harmonic error Berr.

12. The method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to claim 8, characterized in that: The longitudinal wave reflection coefficient percentage error The calculation formula is as follows: The shear wave reflection coefficient percentage error The calculation formula is as follows: The density reflectance percentage error The calculation formula is as follows: in, are the theoretical values ​​of longitudinal wave reflection coefficient, shear wave reflection coefficient and density reflection coefficient, respectively. are the actual values ​​of longitudinal wave reflection coefficient, shear wave reflection coefficient and density reflection coefficient respectively; The calculation formula of the elastic parameter harmonic error Berr is as follows: Among them, a, b, and 1-ab are the importance of the longitudinal wave reflection coefficient, the shear wave reflection coefficient, and the density reflection coefficient, respectively, and all of them are greater than or equal to zero; The calculation formula of the AVO goodness of fit is as follows: P match (1-Berr)×100| Where P match is the AVO fitting degree, which indicates the overall fitting degree between the actual value of the elastic parameter corresponding to the CRP gather near the well and the theoretical value.

13. A calculation system for the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data, characterized in that: include: A wellside theoretical CRP gather generating unit is used for post-stack calibration of the wellside actual and theoretical traces to obtain the calibrated first information, and performs pre-stack calibration in combination with the first information to generate the wellside theoretical CRP gather; A wellside actual CRP gather generating unit is used to obtain the wellside actual CRP gather and determine whether the wellside actual CRP gather meets the basic standard of amplitude preservation. If the wellside actual CRP gather does not meet the basic standard of amplitude preservation, the seismic data is processed and the seismic data processing result is obtained to generate the wellside actual CRP gather; The calculation unit is used to calculate the AVO fit according to the theoretical CRP gathers near the well and the actual CRP gathers near the well.

14. An electronic device, characterized in that: It includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus; a memory storing a computer program; The processor is used to implement the calculation method of the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to any one of claims 1 to 12 when executing the program stored in the memory.

15. A computer-readable storage medium, characterized in that: A computer program is stored, and when the computer program is run, the method for calculating the AVO fitting degree of the pre-stack amplitude preservation evaluation parameter of seismic data according to any one of claims 1 to 12 is executed.

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