Four-dimensional seismic data correction method and system based on multi-scale frequency division waveform matching

Abstract

The application discloses a four-dimensional seismic data correction method and system based on multi-scale frequency division waveform matching, relates to the technical field of seismic data analysis, and comprises the following steps: collecting two times of four-dimensional seismic data of a target oil field in different times and different modes, and obtaining early four-dimensional seismic data and late four-dimensional seismic data; performing preprocessing and wavelet transform frequency division processing based on preset parameters to obtain early frequency division data and late frequency division data in a plurality of preset frequency band ranges; performing inverse wavelet transform based on the preset parameters to obtain early frequency division space-time domain signals and late frequency division space-time domain signals in the plurality of preset frequency band ranges; performing cross-correlation calculation to determine a time offset; and correcting the early frequency division space-time domain signals based on the time offset to obtain data after frequency division waveform matching. The application alleviates the technical problem in the prior art that a time-lapse seismic response caused by fluid change in an oil and gas reservoir cannot be intuitively displayed.

Description

Technical Field

[0001] The present invention relates to the technical field of seismic data analysis, and in particular to a four-dimensional seismic data correction method and system based on multi-scale frequency-division waveform matching. Background Art

[0002] Over time, the remaining oil and gas volume and reservoir locations in underground oil and gas fields change. 4D seismic data collected over the same area at different time intervals is called 4D seismic. 3D seismic exploration yields subsurface seismic data for oil and gas reservoirs. During 4D exploration, only the time attribute should be varied, while all other variables should remain consistent. This ensures the repeatability of 4D seismic data. However, due to differences in observation systems, sensor accuracy, and acquisition methods, the two data collection periods are inconsistent in non-reservoir areas, making it difficult to intuitively display the time-lapse seismic response caused by reservoir fluid changes. Summary of the Invention

[0003] The purpose of the present invention is to provide a four-dimensional seismic data correction method and system based on multi-scale frequency division waveform matching in order to solve at least one of the above technical problems.

[0004] In the first aspect, an embodiment of the present invention provides a four-dimensional seismic data correction method based on multi-scale frequency-division waveform matching, comprising: performing two four-dimensional seismic data acquisitions on a target oil field at different times and in different ways to obtain early four-dimensional seismic data and late four-dimensional seismic data, respectively; pre-processing the early four-dimensional seismic data and the late four-dimensional seismic data and performing wavelet transform frequency division processing based on preset parameters on the early four-dimensional seismic data and the late four-dimensional seismic data, respectively, to obtain early frequency-division data and late frequency-division data within multiple preset frequency bands; the preset parameters include preset scale parameters and preset position parameters; performing inverse wavelet transform based on the preset parameters on the early frequency-division data and the late frequency-division data, respectively, to obtain early frequency-division time-space domain signals and late frequency-division time-space domain signals within the multiple preset frequency bands; performing cross-correlation calculation on the early frequency-division time-space domain signals and the late frequency-division time-space domain signals to determine a time offset; and correcting the early frequency-division time-space domain signals based on the time offset to obtain data after frequency-division waveform matching.

[0005] Furthermore, the preprocessing includes: denoising, time correction and equalization processing.

[0006] Furthermore, the early four-dimensional seismic data and the late four-dimensional seismic data are subjected to wavelet transform frequency division processing based on preset parameters, including:

[0007]

[0008] Where, is the previous frequency division data, is the later frequency division data, D x (a,b) and D y (a, b) are wavelet coefficients, d(x, t) is the early four-dimensional seismic data, d(y, t) is the late four-dimensional seismic data, ψ a,b The wavelet basis functions corresponding to the multiple preset frequency band ranges, a is the preset scale parameter, b is the preset position parameter, f min and f max They are the lower and upper bounds of the preset frequency band respectively.

[0009] Furthermore, the early frequency division data and the late frequency division data are respectively subjected to inverse wavelet transformation based on the preset parameters, including:

[0010]

[0011] Wherein, d′(x, t) is the early frequency-divided time-space domain signal, d′(y, t) is the late frequency-divided time-space domain signal, is the conjugate function of the wavelet basis function.

[0012] Furthermore, performing cross-correlation calculation on the early frequency-divided time-space domain signal and the late frequency-divided time-space domain signal to determine a time offset includes:

[0013]

[0014] Wherein, δt is the time offset.

[0015] Furthermore, the previous frequency-divided time-space domain signal is corrected based on the time offset to obtain data after frequency-divided waveform matching, including:

[0016] d′(x,t) c =d′(x,t+δt)

[0017] Where d′(x,t) c is the data after the frequency-division waveform is matched, δt is the time offset, and d′(x, t) is the previous frequency-division time-space domain signal.

[0018] In a second aspect, an embodiment of the present invention further provides a four-dimensional seismic data correction system based on multi-scale frequency division waveform matching, comprising: an acquisition module, a frequency division module, an inverse transformation module, a calculation module and a correction module; wherein the acquisition module is used to perform two four-dimensional seismic data acquisitions on a target oil field at different times and in different ways, and obtain early four-dimensional seismic data and late four-dimensional seismic data respectively; the frequency division module is used to perform pre-processing and wavelet transformation frequency division processing based on preset parameters on the early four-dimensional seismic data and the late four-dimensional seismic data respectively, and obtain early frequency division data and late four-dimensional seismic data within a plurality of preset frequency bands. Post-frequency division data; the preset parameters include preset scale parameters and preset position parameters; the inverse transformation module is used to perform inverse wavelet transformation based on the preset parameters on the pre-frequency division data and the post-frequency division data, respectively, to obtain the pre-frequency division time-space domain signal and the post-frequency division time-space domain signal within the multiple preset frequency bands; the calculation module is used to perform cross-correlation calculation on the pre-frequency division time-space domain signal and the post-frequency division time-space domain signal to determine the time offset; the correction module is used to correct the pre-frequency division time-space domain signal based on the time offset to obtain data after frequency division waveform matching.

[0019] In a third aspect, an embodiment of the present invention further provides an electronic device comprising: a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the method provided in the embodiment of the present invention when executing the computer program.

[0020] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and when the computer instructions are executed by a processor, the method provided in the embodiment of the present invention is implemented.

[0021] The present invention provides a four-dimensional seismic data correction method and system based on multi-scale frequency division waveform matching. By leveraging the advantages of two-dimensional wavelet transform, the cross-correlation calculation of different frequencies is realized, and the nonlinear and non-stationary characteristic problems of conventional time-space domain waveform matching are improved. At the same time, through cross-correlation time-shift correction, the comparability and consistency of time-shift seismic data between seismic data collected at different times are ensured, the unexpected differences in non-oil and gas reservoir areas are eliminated, and the time-shift seismic impact caused by changes in oil and gas reservoir fluids is highlighted. The technical problem in the prior art that the two phases of collected data are inconsistent in non-reservoir areas due to differences in observation systems, sensor accuracy and acquisition methods, resulting in the inability to intuitively display the time-shift seismic response caused by changes in oil and gas reservoir fluids, is alleviated. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] Figure 1 A four-dimensional seismic data correction method based on multi-scale frequency division waveform matching provided in an embodiment of the present invention is a flow chart;

[0024] Figure 2 A schematic diagram of a seismic cross section of four-dimensional seismic data provided by an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of a frequency-dividing streamer seismic profile provided by an embodiment of the present invention;

[0026] Figure 4 A schematic diagram of a frequency-divided OBC seismic profile provided by an embodiment of the present invention;

[0027] Figure 5 A schematic diagram of a time-lapse streamer seismic profile provided by an embodiment of the present invention;

[0028] Figure 6 A schematic diagram of a four-dimensional seismic data correction system based on multi-scale frequency-division waveform matching provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] Example 1

[0031] Figure 1 FIG. 1 is a flow chart of a four-dimensional seismic data correction method based on multi-scale frequency division waveform matching according to an embodiment of the present invention. Figure 1 As shown, the method specifically includes the following steps:

[0032] Step S102 : collecting four-dimensional seismic data twice at different times and in different ways for the target oil field, and obtaining early four-dimensional seismic data and late four-dimensional seismic data respectively.

[0033] In step S104, the early four-dimensional seismic data and the late four-dimensional seismic data are preprocessed and subjected to wavelet transform frequency division processing based on preset parameters to obtain early frequency division data and late frequency division data within a plurality of preset frequency bands; the preset parameters include preset scale parameters and preset position parameters.

[0034] Step S106 , performing inverse wavelet transform based on preset parameters on the early frequency-divided data and the late frequency-divided data to obtain early frequency-divided space-time domain signals and late frequency-divided space-time domain signals within a plurality of preset frequency bands.

[0035] Step S108 , performing cross-correlation calculation on the early frequency-divided time-space domain signal and the late frequency-divided time-space domain signal to determine a time offset.

[0036] Step S110 , correcting the previous frequency-divided time-space domain signal based on the time offset to obtain data after frequency-divided waveform matching.

[0037] Preferably, the pre-processing in step S104 includes: denoising, time correction and equalization. The two-period data after pre-processing are transformed into the frequency domain using a two-dimensional wavelet transform for analysis. The transformation formula includes:

[0038]

[0039] Where, For the early frequency division data, For the later frequency division data, D x (a,b) and D y (a, b) are wavelet coefficients, d(x, t) is the early four-dimensional seismic data, d(y, t) is the late four-dimensional seismic data, ψ a,b Wavelet basis functions corresponding to multiple preset frequency bands, a is the preset scale parameter, b is the preset position parameter, f min and f max They are the lower and upper bounds of the preset frequency band respectively.

[0040] Specifically, according to the above wavelet transform formula, a suitable wavelet basis function is selected to decompose the frequency range into multiple preset frequency bands, for example, into four preset frequency bands of 5-10 Hz, 10-20 Hz, 20-30 Hz and 30-40 Hz. The wavelet basis function is a Gaussian modulated sine wave:

[0041]

[0042] Where, f c is the center frequency, and a and b are selected so that the center frequency f c satisfy:

[0043] f min <fc <f max

[0044] Through D x (a,b) and D y (a, b) Integrate the results within the corresponding frequency band to obtain the frequency domain representation of the four-dimensional seismic data within the frequency band:

[0045]

[0046] In this way, the four-dimensional seismic data d(x, t) and d(y, t) of the previous and subsequent periods can be decomposed into multiple preset frequency bands (5-10 Hz, 10-20 Hz, 20-30 Hz and 30-40 Hz).

[0047] Specifically, in the inverse wavelet transform of step S106, the scale parameter a and position parameter b are selected to be the same as those in the wavelet transform, and D is converted to freq band Convert to the spatiotemporal domain d′(x, t) and d′(y, t). Specifically, the inverse wavelet transform formula includes:

[0048]

[0049] Where d′(x, t) is the time-space domain signal of the early frequency division, and d′(y, t) is the time-space domain signal of the later frequency division. is the conjugate function of the wavelet basis function.

[0050] The above-mentioned inverse wavelet transform formula can be used to obtain the time-space domain signals of the early four-dimensional seismic data and the late four-dimensional seismic data within multiple preset frequency bands (for example, 5-10 Hz, 10-20 Hz, 20-30 Hz and 30-40 Hz). For example, the corresponding early frequency-divided time-space domain signals within the four preset frequency bands are: d1′(x, t), d2′(x, t), d3′(x, t) and d4′(x, t), and the corresponding late frequency-divided time-space domain signals within the four preset frequency bands are: d1′(y, t), d2′(y, t), d3′(y, t) and d4′(y, t).

[0051] Specifically, in step S108, the arrival time of the P wave in the seismic record is selected as the reference signal, and a cross-correlation calculation is performed on the early frequency-divided time-space domain signal and the late frequency-divided time-space domain signal to determine the time offset:

[0052]

[0053] Where δt is the time offset. The function argmax() represents the value of τ when the integral function within the brackets reaches its maximum value.

[0054] Specifically, the correction in step S110 includes:

[0055] d′(x,t) c =d′(x,r+δt)

[0056] Where d′(x,t) c is the data after matching the frequency division waveform, δt is the time offset, and d′(x, t) is the time-space domain signal of the previous frequency division. For example, for the four preset frequency bands, each frequency band corresponds to a data after matching the frequency division waveform: d1′(x, t) c d2′(x,t) c 、d3′(x,t) c and d4′(x,t) c .

[0057] From the above description, it can be seen that the present invention provides a four-dimensional seismic data correction method based on multi-scale frequency division waveform matching. With the help of the advantages of two-dimensional wavelet transform, the cross-correlation calculation of different frequencies is realized, and the nonlinear and non-stationary characteristics of conventional time-space domain waveform matching are improved. At the same time, through cross-correlation time-shift correction, the comparability and consistency of time-shift seismic data between seismic data collected at different times are ensured, the unexpected differences in non-oil and gas reservoir areas are eliminated, and the time-shift seismic impact caused by changes in oil and gas reservoir fluids is highlighted, alleviating the technical problem of the existing technology that the two phases of data collected are inconsistent in non-reservoir areas due to differences in observation systems, sensor accuracy and acquisition methods, resulting in the inability to intuitively display the time-shift seismic response caused by changes in oil and gas reservoir fluids.

[0058] Example 2

[0059] To better investigate the potential of a particular oilfield, two 3D acquisitions were conducted: the initial acquisition was conducted using an offshore streamer, and the subsequent acquisition was conducted using an OBC (Ocean Bottom Cable). Seismic data collected at different times and methods were processed for non-repetitive time-lapse consistency to eliminate the effects of environmental and human factors. The offshore streamer acquisition consisted of four cables, with a trace spacing of 12.5 meters and a cable spacing of 100 meters, respectively, recording 324 channels per cable. The OBC acquisition consisted of 14 cables, with a trace spacing of 25 meters and a cable spacing of 200 meters, recording 240 channels per cable. The OBC acquisition method provided relatively limited shallow depth coverage, with narrow streamer azimuths and uneven coverage. The streamer's advantage in shallow depths and the oilfield was particularly evident in its clear fault pattern. The first and third sections of the mid-deep stream exhibited the OBC's high coverage, wide reception azimuths, and high resolution.

[0060] Figure 2 : is a schematic diagram of a seismic cross section of four-dimensional seismic data provided according to an embodiment of the present invention. Figure 2As shown, the left figure is the seismic section of the streamer data, and the right figure is the seismic section of the OBC data.

[0061] respectively Figure 2 The streamer data and OBC data shown in the figure are pre-processed and two-dimensional wavelet transformed to four preset frequency bands, namely 5-10Hz, 10-20Hz, 20-30Hz and 30-40Hz, respectively, as shown in the following figure. Figure 3 The four previous frequency division data shown and Figure 4 The four post-frequency division data are shown. Figure 3 A schematic diagram of a frequency-dividing streamer seismic profile provided by an embodiment of the present invention, wherein the four profiles from left to right correspond to four preset frequency bands of 5-10 Hz, 10-20 Hz, 20-30 Hz, and 30-40 Hz, respectively. Figure 4 1 is a schematic diagram of a frequency-divided OBC seismic profile provided according to an embodiment of the present invention. The four profiles from left to right correspond to four preset frequency band ranges of 5-10 Hz, 10-20 Hz, 20-30 Hz and 30-40 Hz, respectively.

[0062] Then, the cross-correlation calculation of the frequency division data is performed to determine the time offset, and then the time offset is used to correct the previous frequency division time and space domain signal to obtain the following: Figure 5 The schematic diagram of the time-lapse streamer seismic profile is shown in FIG. Figure 5 The four cross-sectional views from left to right in the diagram correspond to the four preset frequency bands of 5-10Hz, 10-20Hz, 20-30Hz and 30-40Hz respectively. Figure 5 It can be seen that the method provided by the embodiment of the present invention effectively solves the problem of consistency correction of the previous and subsequent four-dimensional seismic data.

[0063] Example 3

[0064] Figure 6 FIG is a schematic diagram of a four-dimensional seismic data correction system based on multi-scale frequency division waveform matching according to an embodiment of the present invention. Figure 6 As shown, the system includes: an acquisition module 10 , a frequency division module 20 , an inverse transformation module 30 , a calculation module 40 and a correction module 50 .

[0065] Specifically, the acquisition module 10 is used to acquire four-dimensional seismic data twice at different times and in different ways for the target oil field, to obtain early four-dimensional seismic data and late four-dimensional seismic data respectively.

[0066] The frequency division module 20 is used to pre-process the early four-dimensional seismic data and the late four-dimensional seismic data and perform wavelet transform frequency division processing based on preset parameters to obtain early frequency division data and late frequency division data within multiple preset frequency bands; the preset parameters include preset scale parameters and preset position parameters.

[0067] The inverse transform module 30 is used to perform inverse wavelet transform based on preset parameters on the early frequency division data and the late frequency division data to obtain early frequency division time-space domain signals and late frequency division time-space domain signals within multiple preset frequency bands.

[0068] The calculation module 40 is used to perform cross-correlation calculation on the early frequency-divided time-space domain signal and the late frequency-divided time-space domain signal to determine the time offset.

[0069] The correction module 50 is used to correct the previous frequency-divided time-space domain signal based on the time offset to obtain data after frequency-divided waveform matching.

[0070] The present invention also provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method provided in the embodiment of the present invention when executing the computer program.

[0071] The present invention also provides a computer-readable storage medium, which stores computer instructions. When the computer instructions are executed by a processor, the method provided in the embodiment of the present invention is implemented.

[0072] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0073] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A four-dimensional seismic data correction method based on multi-scale frequency division waveform matching, characterized in that: include: The target oil field is collected twice with four-dimensional seismic data at different times and in different ways, obtaining early four-dimensional seismic data and late four-dimensional seismic data respectively; Preprocessing the early four-dimensional seismic data and the late four-dimensional seismic data and performing wavelet transform frequency division processing based on preset parameters respectively to obtain early frequency division data and late frequency division data within a plurality of preset frequency bands; The preset parameters include preset scale parameters and preset position parameters; Performing inverse wavelet transform based on the preset parameters on the early frequency-division data and the late frequency-division data respectively to obtain early frequency-division time-space domain signals and late frequency-division time-space domain signals within the plurality of preset frequency bands; Performing cross-correlation calculation on the early frequency-divided time-space domain signal and the late frequency-divided time-space domain signal to determine a time offset; Correcting the previous frequency-divided time-space domain signal based on the time offset to obtain data after frequency-divided waveform matching; Performing wavelet transform frequency division processing based on preset parameters on the early four-dimensional seismic data and the late four-dimensional seismic data respectively includes: Where, is the previous frequency division data, is the later frequency division data, D x (a,b) and D y (a, b) are wavelet coefficients, d(x, t) is the early four-dimensional seismic data, d(y, t) is the late four-dimensional seismic data, ψ a,b is the wavelet basis function corresponding to the multiple preset frequency bands, a is the preset scale parameter, b is the preset position parameter, f min and f max They are the lower and upper bounds of the preset frequency band respectively.

2. The method according to claim 1, wherein: The preprocessing includes: denoising, time correction and equalization processing.

3. The method according to claim 1, wherein: The early frequency division data and the late frequency division data are respectively subjected to inverse wavelet transformation based on the preset parameters, comprising: Wherein, d′(x, t) is the early frequency-divided time-space domain signal, d′(y, t) is the late frequency-divided time-space domain signal, is the conjugate function of the wavelet basis function.

4. The method according to claim 3, wherein: Performing cross-correlation calculation on the early frequency-divided time-space domain signal and the late frequency-divided time-space domain signal to determine a time offset includes: Wherein, δt is the time offset.

5. The method according to claim 4, characterized in that: Correcting the previous frequency-divided time-space domain signal based on the time offset to obtain data after frequency-divided waveform matching includes: d′(x,t) c =d′(x,t+δt) Where d′(x,t) c is the data after the frequency-division waveform is matched, δt is the time offset, and d′(x, t) is the previous frequency-division time-space domain signal.

6. A four-dimensional seismic data correction system based on multi-scale frequency division waveform matching, characterized in that: Used to implement the method described in any one of claims 1-5; comprising: an acquisition module, a frequency division module, an inverse transformation module, a calculation module and a correction module; wherein, The acquisition module is used to acquire four-dimensional seismic data twice at different times and in different ways for the target oil field, respectively obtaining early four-dimensional seismic data and late four-dimensional seismic data; The frequency division module is used to pre-process the early four-dimensional seismic data and the late four-dimensional seismic data and perform wavelet transform frequency division processing based on preset parameters to obtain early frequency division data and late frequency division data within a plurality of preset frequency bands; the preset parameters include preset scale parameters and preset position parameters; The inverse transform module is used to perform inverse wavelet transform based on the preset parameters on the early frequency division data and the late frequency division data, respectively, to obtain early frequency division time-space domain signals and late frequency division time-space domain signals within the multiple preset frequency bands; The calculation module is used to perform cross-correlation calculation on the early frequency-divided time-space domain signal and the late frequency-divided time-space domain signal to determine a time offset; The correction module is used to correct the previous frequency-divided time-space domain signal based on the time offset to obtain data after frequency-divided waveform matching.

7. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the method according to any one of claims 1 to 5 when executing the computer program.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, and when the computer instructions are executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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