Seismic trace gather far offset energy preserving processing method

Abstract

The invention provides a seismic trace gather far offset energy preserving processing method, which comprises the following steps of: 1, decompiling field seismic data, and performing first arrival picking and trace gather extraction processing; 2, performing high-order dynamic correction processing on the extracted gather data to improve the influence of conventional dynamic correction stretching on the far offset; step 3, performing space-time variation cutting on gather first arrival waves and interference waves by adopting control points; step 4, performing offset resolution improvement processing on the gather data, and further improving the frequency dispersion problem of the far-offset data; and step 5, carrying out deconvolution, superposition and migration processing on the far-offset information preserving gather to obtain far-offset energy preserving seismic result data. According to the seismic trace gather far-offset energy maintaining processing method, recovery and maintenance of far-offset energy in seismic trace gather data can be realized, the imaging quality of seismic data of middle and shallow layers is improved, and recovery and maintenance of far-offset information are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of seismic data processing, and in particular to a method for processing far-offset energy of seismic trace gathers. Background Art

[0002] With the widespread application of wide-angle exploration technology and the increasing complexity of exploration targets, higher requirements are being placed on the imaging processing accuracy of seismic event axes. Preserving energy at far-offsets is crucial for accurate event imaging. Although currently acquired mid- and shallow-seismic data and raw gathers have large effective offsets, the effects of dynamic correction processing technology and the accuracy of offset velocities can cause a certain degree of waveform stretching and distortion in mid- and long-offset reflection axes, affecting the resolution and fidelity of the stacking results. Therefore, it is urgently necessary to develop seismic data processing technologies that preserve energy and information at far-offsets, achieve the preservation of seismic information under wide-angle reflections, and improve the accuracy of geological characterization.

[0003] Chinese patent application number CN201710953912.4 discloses a method and system for segmented amplitude energy compensation of prestack seismic gathers. The method may include: calculating depth-domain forward modeling gather data based on well logs and seismic data, and converting it into time-domain forward modeling gather data; calculating the offset response equation of the forward gather, the offset response equation of the actual prestack seismic gather, and the curvature of the offset response equation of the actual prestack seismic gather based on the time-domain forward modeling gather data and the actual prestack seismic gather data; setting a cutoff point to group the offsets and separately calculating the large-offset response equation and the small-offset response equation; replacing the gradient with the forward modeling gather gradient, calculating the intercept value, and obtaining the compensated offset response equation; and obtaining the difference in amplitude values ​​at each offset position to obtain the compensated prestack seismic gather. This invention can perform amplitude compensation of prestack seismic gather data, improve the accuracy of prestack reservoir prediction and prestack fracture prediction, and provide stronger technical support for exploration and development.

[0004] Chinese patent application number CN201811550994.9 discloses a time-domain full-waveform inversion method based on a zero-mean normalized cross-correlation objective function. This method replaces the least-squares objective function used in traditional full-waveform inversion by calculating the zero-mean normalized cross-correlation between simulated and observed data. Normalized cross-correlation ensures that the absolute values ​​of the amplitudes of the simulated and observed data are between -1 and 1, effectively reducing inversion errors caused by amplitude errors. Furthermore, the normalization of amplitude energy increases the energy weight of far-offset data in seismic records. Because far-offset data carry information about large-scale structures in the model, this method can reduce cycle skipping. Because real seismic records are susceptible to low-frequency noise, often non-mean noise, a demeaning term is introduced. By demeaning the simulated and observed records, the interference of low-frequency noise is reduced. This method can accurately invert subsurface velocity parameters even when low-frequency information is missing or contaminated by noise.

[0005] Chinese patent application number CN201010610767.8 discloses a method for identifying pre-stack low-frequency signals in complex oil reservoirs. The method involves using artificially excited seismic waves to acquire raw seismic data and thereby obtain a stratigraphic file for the target layer. The method then selects the optimal time window within the stratigraphic file to identify the target layer. The pre-stack seismic data within the target layer are then separated into near-, medium-, and far-offset data. Spectral analysis is then performed on the data within the target layer to determine the optimal oil and gas-sensitive frequency bands for the pre-stack and post-stack seismic data. Frequency division techniques are then used to extract low- and high-frequency information from the seismic waves within the target layer within these optimal oil and gas-sensitive frequency bands. The presence of oil and gas is detected by utilizing the characteristic of enhanced energy in low-frequency bands and weakened energy in high-frequency bands. Finally, the method compares the results with known exploration wells, analyzes them, and outputs the results. This invention, based on a two-phase medium model that more closely resembles the actual underground conditions, utilizes pre-stack low-frequency signals with richer information to identify oil and gas reservoirs. Compared to traditional indirect and direct methods, the method offers the advantages of lower cost and higher accuracy.

[0006] The above existing technologies are significantly different from the present invention and fail to solve the technical problem we want to solve. Therefore, we have invented a new method for energy preservation processing of far-offset seismic gathers. Summary of the Invention

[0007] The purpose of the present invention is to provide a seismic gather far-offset energy preservation processing method which can realize the recovery and preservation of far-offset energy in seismic gather data and improve the imaging quality of medium-shallow seismic data.

[0008] The object of the present invention can be achieved by the following technical measures: a method for processing far-offset energy of a seismic trace gather, the method comprising:

[0009] Step 1: decode the field seismic data, and perform first arrival picking and gather extraction processing;

[0010] Step 2: Perform high-order dynamic correction on the extracted gather data to improve the effect of conventional dynamic correction stretching on far offsets;

[0011] Step 3: Use control points to perform time-space variation removal on the first arrival wave and interference wave of the gather;

[0012] Step 4: Process the gather data by offset to improve the resolution and further improve the dispersion problem of far-offset data.

[0013] Step 5: Deconvolution, stacking and migration processing are performed on the far-offset information-preserving gathers to obtain seismic data with far-offset energy preservation.

[0014] The purpose of the present invention can also be achieved by the following technical measures:

[0015] In step 1, the field seismic data is decoded, the volume header and trace header information are checked and edited, blank shots, waste traces and empty traces are deleted or replaced, and the first arrival and trace collection processing are performed.

[0016] In step 2, conventional hyperbolic NMO correction is based on the DIX formula, which retains only the first two low-order terms of the Taylor expansion of the time-distance function and ignores the higher-order terms of the expansion. The low-order terms can accurately describe the time-distance relationship of seismic events in isotropic media at close offsets, but will produce distortion when corrected at far offsets. Therefore, the higher-order terms must be considered when correcting far-offset events.

[0017] In step 2, the conventional hyperbolic motion correction formula is:

[0018]

[0019] Where t0 is the zero-offset two-way propagation time of the seismic wave, x is the offset distance, V rms is the root mean square velocity.

[0020] Based on the conventional hyperbolic NMO correction and processing objectives, an optimized sixth-order anisotropic moveout correction is proposed:

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027] Where △t k For the vertical travel time of the kth layer, V k is the kth layer velocity, C * is the Taylor expansion coefficient.

[0028] High-order dynamic correction processing reduces the transformation of far offsets caused by conventional hyperbolic dynamic correction stretching and retains more far offset information.

[0029] In step 3, control points are used to perform spatiotemporal excision. The excision position can be adjusted in time according to the effective offset of the seismic gather. While ensuring the excision of the first arrival wave and the interference wave, the far-offset energy is maintained to the maximum extent, which can effectively protect the far-offset information of complex structural parts.

[0030] In step 4, the far-offset data are processed for resolution enhancement based on offset. Due to the difference in the main frequency of each channel in the CIP gather, a frequency enhancement operator that varies with the offset can be designed to perform frequency enhancement on each channel, thereby achieving resolution enhancement based on offset, improving the far-offset resolution, improving the consistency of the resolution at near, medium and far offsets, and improving the overall resolution of the data.

[0031] In step 4, the main frequency of the target layer of the CIP gather is obtained, and the frequency boost operator is designed according to the main frequency difference of the near, medium and far offsets. Q compensation is performed according to the main frequency difference of each trace in the CIP gather. Assuming that the frequency domain seismic trace with τ = O on the surface is U(O, ω) and the time domain seismic trace after inverse Q filtering is U(τ), then

[0032]

[0033] Where: Λ(τ, ω) is a stable amplitude compensation operator, γ(τ) is a time-varying attenuation parameter, γ(τ) = [πQ(τ)] -1 ;ω h is the reference frequency.

[0034] In step 4, based on the difference in main frequency of each channel in the CIP gather, a frequency-boosting operator that varies with offset can be designed to perform frequency boost on a channel-by-channel basis, thereby achieving offset-based resolution enhancement, improving far-offset resolution, and improving the consistency of resolution at near, medium, and far offsets, while also improving the overall resolution of the data.

[0035] In step 5, the gathers that have undergone the high-order dynamic correction processing of time-space variation excision, time-space variation excision, and offset resolution enhancement processing are stacked and offset processed to obtain seismic data with energy preservation at far offsets.

[0036] The object of the present invention can also be achieved through the following technical measures: a seismic track gather far-offset energy preservation processing system, which uses a seismic track gather far-offset energy preservation processing method to recover and preserve far-offset information.

[0037] The far-offset energy preservation processing method of the seismic track gather in the present invention is used for reservoir prediction in oil exploration. First, based on the decoding of field seismic data, the volume header and track header information are checked and edited, the empty shots, abandoned tracks and empty tracks are deleted or replaced, and the first arrival and track gather processing are performed; then, the extracted track gather data are subjected to high-order dynamic correction processing to effectively improve the influence of conventional dynamic correction stretching on the far-offset; then, the first arrival wave and interference wave of the track gather are subjected to time-space variation excision using control points; after that, the far-offset data are subjected to offset-based resolution improvement processing to further improve the dispersion problem of the far-offset data; finally, the far-offset information-maintaining track gather is subjected to deconvolution, stacking and offset processing to obtain seismic result data with far-offset energy preservation. The advantages of the present invention are: based on high-order dynamic correction and time-space variation excision technology, the far-offset information of complex structural parts is effectively protected, and the far-offset dispersion problem is improved by offset-based resolution improvement processing, so that the result data after stacking and offset contain more far-offset information, which significantly improves the prediction effect for complex structural parts and medium and shallow reservoirs.

[0038] Compared with the prior art, the present invention provides a far-offset energy preservation processing method for seismic trace gathers, which has the following beneficial effects: high-order dynamic correction can reduce the modification of far-offset caused by conventional hyperbolic dynamic correction stretching, thereby retaining more far-offset information; the use of control points for spatiotemporal variation excision can effectively protect far-offset information in complex structural areas and improve imaging in medium and deep layers; resolution enhancement processing by offset division can improve far-offset dispersion problems; and finally, far-offset information can be recovered and preserved, thereby improving the accuracy of imaging in medium and shallow layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A flowchart of a specific embodiment of the method for processing far-offset energy preservation of seismic trace gathers according to the present invention;

[0040] Figure 2 Schematic diagram of a comparison cross section between conventional dynamic correction and high-order dynamic correction in a specific embodiment of the present invention;

[0041] Figure 3 A comparison diagram of spatiotemporal control point excision and conventional linear excision in a specific embodiment of the present invention;

[0042] Figure 4 A comparison diagram of a gather processed by offset-based resolution enhancement and a conventional gather in a specific embodiment of the present invention;

[0043] Figure 5 A comparison diagram of a conventional stacking section and a stacking section processed with energy preservation at a far offset in a specific embodiment of the present invention;

[0044] Figure 6 1 is a comparison diagram of a conventional stacking section and a stacking section after far-offset energy preservation processing in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0045] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0046] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations and / or combinations thereof.

[0047] The technical problem to be solved by the present invention is that when processing seismic data, the energy of far-offset information is relatively weak. Conventional dynamic correction methods cause distortion of the far-offset information in the gather, while the single first-arrival and interference wave removal technology removes the distorted information at the same time, resulting in loss of far-offset information. A method for preserving the far-offset energy of a seismic gather is provided.

[0048] The technical solution adopted by the present invention to solve its technical problems is as follows: high-order dynamic correction processing is performed on the extracted seismic gather data to effectively improve the influence of conventional dynamic correction stretching on the far offset; control points are used to perform time-space variation to remove the first arrival wave and interference wave of the gather; the far offset data is processed by offset to improve the resolution, and the far offset dispersion problem is further improved; finally, the processed gather is deconvolved, stacked and offset processed to obtain seismic data with energy preservation at far offset.

[0049] The method for preserving energy of seismic trace gathers at far offsets of the present invention comprises:

[0050] S1. Decode the field seismic data, check and edit the volume header and trace header information, delete or replace empty shots, abandoned traces, and empty traces, and perform first arrival and trace collection processing;

[0051] S2. Perform high-order dynamic correction on the extracted gather data to effectively improve the effect of conventional dynamic correction stretching on far offsets;

[0052] S3, use control points to perform time-space variation removal on the first arrival wave and interference wave of the gather;

[0053] S4. Process the gather data by offset to improve the resolution and further improve the dispersion problem of far-offset data.

[0054] S5. Deconvolution, stacking and migration processing are performed on the far-offset information-preserving gathers to obtain seismic data with far-offset energy preservation.

[0055] In step S2, high-order dynamic correction processing is performed on the extracted gather data to reduce the transformation of the far offset by conventional hyperbolic dynamic correction stretching and retain more far offset information.

[0056] The conventional hyperbolic motion correction formula is:

[0057]

[0058] Where t0 is the zero-offset two-way propagation time of the seismic wave, x is the offset distance, V rms is the root mean square velocity.

[0059] Based on the conventional hyperbolic NMO correction and processing objectives, an optimized sixth-order anisotropic moveout correction is proposed:

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066] Where △t k For the vertical travel time of the kth layer, V k is the kth layer velocity, C * is the Taylor expansion coefficient.

[0067] In step S3, during conventional gather processing, if the structure of the work area is relatively complex, the use of a single first arrival wave and interference wave excision can easily cause erroneous excision of medium and deep layer information, affecting the preservation of medium and deep layer far-offset information. Control points are used for time-space variable excision, and the excision position can be adjusted in time according to the effective offset of the seismic gather. While ensuring the excision of the first arrival wave and interference wave, the far-offset energy is maintained to the maximum extent, which can effectively protect the far-offset information of complex structural parts.

[0068] In step S4, the resolution is improved by offset separation to improve the dispersion problem at far offsets.

[0069] Obtain the main frequency of the target layer of the CIP gather, design a frequency boost operator based on the main frequency difference of the near, medium and far offsets, and perform Q compensation based on the main frequency difference of each trace in the CIP gather. Assuming that the frequency domain seismic trace with τ = O on the surface is U(O, ω) and the time domain seismic trace after inverse Q filtering is U(τ), then

[0070]

[0071] Where: Λ(τ, ω) is a stable amplitude compensation operator, γ(τ) is a time-varying attenuation parameter, γ(τ) = [πQ(τ)] -1 ;ω h is the reference frequency.

[0072] In step S5, the gathers that have undergone the high-order dynamic correction processing of time-space variation excision, time-space variation excision, and offset resolution enhancement processing are stacked and offset processed to obtain seismic data with energy preservation at far offsets.

[0073] The following are several specific embodiments of the present invention:

[0074] Example 1

[0075] In a specific embodiment 1 of the present invention, Figure 1 As shown, the present invention provides a method for processing far-offset energy of seismic gathers for reservoir prediction in oil exploration.

[0076] Step 1: Based on the decompilation of field seismic data, the volume header and trace header information are checked and edited, blank shots, abandoned traces, and empty traces are deleted or replaced, and the first arrival and trace collection processing are performed;

[0077] Step 2: Perform high-order NMO on the extracted gather data. Conventional hyperbolic NMO is based on the DIX formula, which retains only the first two low-order terms of the Taylor expansion of the time-distance function and ignores the higher-order terms. Low-order terms accurately describe the time-distance relationship of seismic events in isotropic media at close offsets, but they produce distortion at far offsets. Therefore, high-order terms must be considered when performing NMO on events at far offsets.

[0078] The conventional hyperbolic motion correction formula is:

[0079]

[0080] Where t0 is the zero-offset two-way propagation time of the seismic wave, x is the offset distance, V rms is the root mean square velocity.

[0081] Based on the conventional hyperbolic NMO correction and processing objectives, an optimized sixth-order anisotropic moveout correction is proposed:

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088] Where △t k For the vertical travel time of the kth layer, V k is the kth layer velocity, C * is the Taylor expansion coefficient.

[0089] High-order dynamic correction processing reduces the transformation of far offsets caused by conventional hyperbolic dynamic correction stretching and retains more far offset information.

[0090] Step 3: Use control points to perform time-space variation removal on the high-order NMO gathers to remove the first arrival wave and interference wave.

[0091] When processing conventional gathers, if the structure of the work area is relatively complex, the use of a single first-arrival wave and interference wave excision can easily cause erroneous excision of medium-deep layer information, affecting the preservation of medium-deep layer far-offset information. Control points are used for time-space-varying excision, and the excision position can be adjusted in time according to the effective offset of the seismic gather. While ensuring the excision of the first-arrival wave and interference wave, the far-offset energy is maintained to the maximum extent, which can effectively protect the far-offset information of complex structural parts.

[0092] Step 4: Perform offset-based resolution enhancement on the far-offset data. Due to the different dominant frequencies of each trace in the CIP gather, a frequency-boosting operator can be designed that varies with offset to perform frequency enhancement on each trace. This allows for offset-based resolution enhancement, improving far-offset resolution, and refining resolution consistency at near, medium, and far offsets, while also increasing the overall resolution of the data.

[0093] Obtain the main frequency of the target layer of the CIP gather, design a frequency boost operator based on the main frequency difference of the near, medium and far offsets, and perform Q compensation based on the main frequency difference of each trace in the CIP gather. Assuming that the frequency domain seismic trace with τ = O on the surface is U(O, ω), and the time domain seismic trace after inverse Q filtering is U(τ), then

[0094]

[0095] Where: Λ(τ, ω) is a stable amplitude compensation operator, γ(τ) is a time-varying attenuation parameter, γ(τ) = [πQ(τ)] -1 ;ω h is the reference frequency.

[0096] Step 5: Stack and migrate the gathers that have undergone high-order dynamic correction processing, spatial-temporal variation excision, and offset resolution enhancement processing to obtain seismic data with energy preservation at far offsets.

[0097] Example 2

[0098] In a specific embodiment 2 of the present invention, Figure 2 The following figure shows the results of the dynamic normalization (NMO) processing in a specific embodiment of the present invention. The left figure shows the results of conventional hyperbolic NMO, and the right figure shows the results of high-order NMO. As can be seen from the left figure, the hyperbolic NMO results are reasonable at near-mid-offset locations, and the events are effectively flattened. However, at far-offset locations, especially in the mid-shallow layers, significant eastward stretching is observed. The right figure shows the results after high-order NMO processing using the inventive method. While the correction results are reasonable at near-mid-offset locations and the events are effectively flattened, the far-offset information is well restored, and the events are also effectively flattened.

[0099] Figure 3 This figure shows a schematic diagram of the spatiotemporal variation excision process in a specific embodiment of the present invention. The left figure illustrates a conventional excision method, while the right figure illustrates a control point spatiotemporal variation excision method. As can be seen from the left figure, the conventional excision method is a simple linear excision method that tends to remove some valid far-offset information during interference wave excision in seismic gathers. The right figure illustrates the control point spatiotemporal variation excision method using the inventive method. During interference wave excision, the appropriate interference wave boundary is automatically identified and the excision location is determined based on the control point positions, preserving the far-offset information to the greatest extent possible.

[0100] Figure 4 This is a diagram showing the results of offset-based resolution enhancement in a specific embodiment of the present invention. Figure a shows a conventional CIP gather, Figure b shows a conventional CIP gather after single resolution enhancement processing, Figure c shows a CIP gather after offset-based resolution enhancement processing, and Figure d shows a comparison of gather spectra before and after processing. As can be seen from Figure a, the conventional CIP gather has weak event energy at far-offset positions, and the event energy dispersion phenomenon increases with increasing offset. Figure c shows the CIP gather result after offset-based resolution enhancement processing. By designing a frequency enhancement operator that varies with offset, frequency enhancement is performed on each channel, achieving offset-based resolution enhancement processing and improving far-offset resolution. Compared with the conventional single resolution enhancement processing result (Figure b), the consistency of resolution at near, medium, and far offsets is further improved, while also improving the overall resolution of the data.

[0101] Figure 5This is a diagram showing the result of far-offset energy preservation processing of seismic traces in a specific embodiment of the present invention. The left figure is a pre-stack time migration section after conventional processing, and the right figure is a pre-stack time migration section after far-offset energy preservation processing of seismic traces. As can be seen from the left figure, due to the loss of some far-offset information by conventional processing methods, some event axes in the section after stacking and migration are relatively weak, especially the continuity and reflection intensity of the event axes in the middle and shallow layers are relatively weak. The right figure is a pre-stack time migration section after far-offset energy preservation processing of seismic traces. Based on high-order dynamic correction and spatiotemporal variation excision technology, the far-offset information of complex structural parts is effectively protected, and the resolution is improved by offset-based processing to improve the far-offset dispersion problem, so that the result data after stacking and migration contain more far-offset information, which significantly improves the prediction effect for complex structural parts and middle and shallow reservoirs.

[0102] Example 3

[0103] In a specific embodiment 3 of the present invention, as Figure 1 As shown, the present invention provides a method for processing far-offset energy of seismic gathers for reservoir prediction in oil exploration.

[0104] Step 1: Based on the decompilation of field seismic data, the volume header and trace header information are checked and edited, blank shots, abandoned traces, and empty traces are deleted or replaced, and the first arrival and trace collection processing are performed;

[0105] Step 2: Perform high-order NMO on the extracted gather data. Conventional hyperbolic NMO is based on the DIX formula, which retains only the first two low-order terms of the Taylor expansion of the time-distance function and ignores the higher-order terms. Low-order terms accurately describe the time-distance relationship of seismic events in isotropic media at close offsets, but they produce distortion at far offsets. Therefore, high-order terms must be considered when performing NMO on events at far offsets.

[0106] The conventional hyperbolic motion correction formula is:

[0107]

[0108] Where t0 is the zero-offset two-way propagation time of the seismic wave, x is the offset distance, V rms is the root mean square velocity.

[0109] Based on the conventional hyperbolic NMO correction and processing objectives, an optimized sixth-order anisotropic moveout correction is proposed:

[0110]

[0111]

[0112]

[0113]

[0114]

[0115]

[0116] Where △t k For the vertical travel time of the kth layer, V k is the kth layer velocity, C * is the Taylor expansion coefficient.

[0117] High-order dynamic correction processing reduces the transformation of far offsets caused by conventional hyperbolic dynamic correction stretching and retains more far offset information.

[0118] Step 3: Use control points to perform time-space variation removal on the high-order NMO gathers to remove the first arrival wave and interference wave.

[0119] When processing conventional gathers, if the structure of the work area is relatively complex, the use of a single first-arrival wave and interference wave excision can easily cause erroneous excision of medium-deep layer information, affecting the preservation of medium-deep layer far-offset information. Control points are used for time-space-varying excision, and the excision position can be adjusted in time according to the effective offset of the seismic gather. While ensuring the excision of the first-arrival wave and interference wave, the far-offset energy is maintained to the maximum extent, which can effectively protect the far-offset information of complex structural parts.

[0120] Step 4: Perform offset-based resolution enhancement on the far-offset data. Due to the different dominant frequencies of each trace in the CIP gather, a frequency-boosting operator can be designed that varies with offset to perform frequency enhancement on each trace. This allows for offset-based resolution enhancement, improving far-offset resolution, and refining resolution consistency at near, medium, and far offsets, while also increasing the overall resolution of the data.

[0121] Obtain the main frequency of the target layer of the CIP gather, design a frequency boost operator based on the main frequency difference of the near, medium and far offsets, and perform Q compensation based on the main frequency difference of each trace in the CIP gather. Assuming that the frequency domain seismic trace with τ = O on the surface is U(O, ω), and the time domain seismic trace after inverse Q filtering is U(τ), then

[0122]

[0123] Where: Λ(τ, ω) is a stable amplitude compensation operator, γ(τ) is a time-varying attenuation parameter, γ(τ) = [πQ(τ)] -1 ;ω h is the reference frequency.

[0124] Step 5: Stack and migrate the gathers that have undergone high-order dynamic correction processing, spatial-temporal variation excision, and offset resolution enhancement processing to obtain seismic data with energy preservation at far offsets.

[0125] Figure 6 This is a diagram showing the result of far-offset energy preservation processing of seismic traces in a specific embodiment of the present invention. The left figure is a pre-stack time migration section after conventional processing, and the right figure is a pre-stack time migration section after far-offset energy preservation processing of seismic traces. As can be seen from the left figure, due to the loss of some far-offset information by conventional processing methods, some event axes in the section after stacking and migration are relatively weak, especially the continuity and reflection intensity of the event axes in the middle and shallow layers are relatively weak. The right figure is a pre-stack time migration section after far-offset energy preservation processing of seismic traces. Based on high-order dynamic correction and spatiotemporal variation excision technology, the far-offset information of complex structural parts is effectively protected, and the resolution is improved by offset-based processing to improve the far-offset dispersion problem, so that the result data after stacking and migration contain more far-offset information, which significantly improves the prediction effect for complex structural parts and middle and shallow reservoirs.

[0126] The present invention relates to the field of oil and gas geophysical exploration and provides a method for preserving far-offset energy in seismic gather data. This method can restore and preserve far-offset energy in seismic gather data, improving the imaging quality of shallow-to-medium seismic data. By using high-order dynamic correction (NMO), the method reduces the effects of conventional hyperbolic dynamic correction (NMO) stretching on far-offset data; employs control points for spatiotemporal excision to effectively protect far-offset information in complex structures; and employs offset-based resolution enhancement processing to improve far-offset dispersion. This method achieves the restoration and preservation of far-offset information, improving the accuracy of shallow-to-medium imaging.

[0127] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art may modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features therein. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

[0128] Except for the technical features described in the specification, all other technical features are known technologies to those skilled in the art.

Claims

1. A method for preserving energy in far-offset seismic traces, characterized in that: The far-offset energy preservation processing method of the seismic trace gathers includes: Step 1: decode the field seismic data, and perform first arrival picking and gather extraction processing; Step 2: Perform high-order dynamic correction on the extracted gather data to improve the effect of conventional dynamic correction stretching on far offsets; Step 3: Use control points to perform time-space variation removal on the first arrival wave and interference wave of the gather; Step 4: Process the gather data by offset to improve the resolution and further improve the dispersion problem of far-offset data. Step 5: Deconvolution, stacking and migration processing are performed on the far-offset information-preserving gathers to obtain seismic data with far-offset energy preservation.

2. The method for processing far-offset energy of seismic traces according to claim 1, characterized in that: In step 1, the field seismic data is decoded, the volume header and trace header information are checked and edited, blank shots, waste traces and empty traces are deleted or replaced, and the first arrival and trace collection processing are performed.

3. The method for processing far-offset energy of seismic traces according to claim 1, characterized in that: In step 2, conventional hyperbolic NMO correction is based on the DIX formula, which retains only the first two low-order terms of the Taylor expansion of the time-distance function and ignores the higher-order terms of the expansion. The low-order terms can accurately describe the time-distance relationship of seismic events in isotropic media at close offsets, but will produce distortion when corrected at far offsets. Therefore, the higher-order terms must be considered when correcting far-offset events.

4. The method for processing far-offset energy of seismic traces according to claim 3, characterized in that: In step 2, the conventional hyperbolic motion correction formula is: Where t0 is the zero-offset two-way propagation time of the seismic wave, x is the offset distance, V rms is the root mean square velocity; Based on the conventional hyperbolic NMO correction and processing objectives, an optimized sixth-order anisotropic moveout correction is proposed: Where △t k For the vertical travel time of the kth layer, V k is the kth layer velocity, C * is the Taylor expansion coefficient; High-order dynamic correction processing reduces the transformation of far offsets caused by conventional hyperbolic dynamic correction stretching and retains more far offset information.

5. The method for processing far-offset energy of seismic traces according to claim 1, characterized in that: In step 3, control points are used to perform spatiotemporal excision. The excision position can be adjusted in time according to the effective offset of the seismic gather. While ensuring the excision of the first arrival wave and the interference wave, the far-offset energy is maintained to the maximum extent, which can effectively protect the far-offset information of complex structural parts.

6. The method for processing far-offset energy of seismic traces according to claim 1, characterized in that: In step 4, the far-offset data are processed for resolution enhancement based on offset. Due to the difference in the main frequency of each channel in the CIP gather, a frequency enhancement operator that varies with the offset can be designed to perform frequency enhancement on each channel, thereby achieving resolution enhancement based on offset, improving the far-offset resolution, improving the consistency of the resolution at near, medium and far offsets, and improving the overall resolution of the data.

7. The method for processing far-offset energy of seismic traces according to claim 6, characterized in that: In step 4, the main frequency of the target layer of the CIP gather is obtained, and the frequency boost operator is designed according to the main frequency difference of the near, medium and far offsets. Q compensation is performed according to the main frequency difference of each trace in the CIP gather. Assuming that the frequency domain seismic trace with τ = O on the surface is U(O, ω) and the time domain seismic trace after inverse Q filtering is U(τ), then Where: Λ(τ, ω) is a stable amplitude compensation operator, γ(τ) is a time-varying attenuation parameter, γ(τ) = [πQ(τ)] -1 ;ω h is the reference frequency.

8. The method for processing far-offset energy of seismic traces according to claim 7, characterized in that: In step 4, based on the difference in main frequency of each channel in the CIP gather, a frequency-boosting operator that varies with offset can be designed to perform frequency boost on a channel-by-channel basis, thereby achieving offset-based resolution enhancement, improving far-offset resolution, and improving the consistency of resolution at near, medium, and far offsets, while also improving the overall resolution of the data.

9. The method for processing far-offset energy of seismic traces according to claim 1, characterized in that: In step 5, the gathers that have undergone the high-order dynamic correction processing of time-space variation excision, time-space variation excision, and offset resolution enhancement processing are stacked and offset processed to obtain seismic data with energy preservation at far offsets.

10. A seismic trace gather far-offset energy retention processing system, characterized in that: The seismic track gather far-offset energy preservation processing system uses the seismic track gather far-offset energy preservation processing method according to any one of claims 1 to 9 to recover and preserve far-offset information.

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