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

Abstract

The invention discloses a four-dimensional seismic data correction method and system based on multi-scale frequency division waveform matching, and relates to the technical field of seismic data analysis, and the method comprises the steps: carrying out the two times of four-dimensional seismic data collection of a target oil field in different time and different modes, and obtaining the earlier-stage four-dimensional seismic data and the later-stage four-dimensional seismic data; performing preprocessing and wavelet transform frequency division processing based on preset parameters to obtain early-stage frequency division data and later-stage frequency division data in a plurality of preset frequency band ranges; performing inverse wavelet transform based on preset parameters to obtain early-stage frequency division time-space domain signals and later-stage frequency division time-space domain signals in a plurality of preset frequency band ranges; performing cross-correlation calculation to determine a time offset; and correcting the earlier-stage frequency division time-space domain signal based on the time offset to obtain data after frequency division waveform matching. The technical problem that in the prior art, time-lapse seismic response caused by oil and gas reservoir fluid changes cannot be visually displayed is solved.

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] As time goes by, the remaining amount of oil and gas and the location of oil and gas reservoirs in underground oil and gas fields will change. Collecting seismic data in the same area at different time intervals is four-dimensional seismic. After three-dimensional seismic exploration, underground seismic data of oil and gas reservoirs can be obtained. When conducting four-dimensional exploration, only the time attribute should be different, and other variables should remain consistent, so as to maintain the repeatability of four-dimensional seismic data. However, due to differences in observation systems, sensor accuracy and acquisition methods, the two phases of data collected are inconsistent in non-reservoir areas, resulting in the inability to intuitively display the time-lapse seismic response caused by changes in oil and gas reservoir fluids. 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 four-dimensional seismic data acquisition twice at different times and in different ways on a target oil field to obtain 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 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 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] Further, the early four-dimensional seismic data and the late four-dimensional seismic data are respectively subjected to wavelet transform frequency division processing based on preset parameters, including:

[0007]

[0008] In the formula, 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 limits of the preset frequency band range 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] Further, performing 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 includes:

[0013]

[0014] Wherein, δt is the time offset.

[0015] Further, 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, and obtain early frequency division data and late four-dimensional seismic data within multiple preset frequency bands. The 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 the data after the frequency division waveform is matched.

[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 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.

[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, which utilizes the advantages of two-dimensional wavelet transform to realize cross-correlation calculation of different frequencies, improves the nonlinear and non-stationary characteristic problems of conventional time-space domain waveform matching, and at the same time, through cross-correlation time-shift correction, ensures that time-shift seismic data collected in different times are comparable and consistent, eliminates unexpected differences in non-oil and gas reservoir areas, highlights the impact of time-shift seismic caused by changes in oil and gas reservoir fluids, and alleviates the technical problem in the prior art 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. 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 drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. 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 paying 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 profile 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 be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0030] Embodiment 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 comprises the following steps:

[0032] Step S102, collecting 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.

[0033] Step S104, 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 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.

[0034] Step S106, performing inverse wavelet transform based on 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 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 the 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 preprocessing in step S104 includes: denoising, time correction and equalization. The preprocessed two-period data is transformed into the frequency domain using a two-dimensional wavelet transform for analysis, and the transformation formula includes:

[0038]

[0039] In the formula, For the previous frequency division data, For 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 later four-dimensional seismic data, ψ a,b Wavelet basis functions corresponding to multiple preset frequency band ranges, a is a preset scale parameter, b is a preset position parameter, f min and f max They are the lower and upper limits of the preset frequency band range 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] In the formula, 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 same scale parameter a and position parameter b as those in the wavelet transform are selected, and D is converted into freq band Convert to the time-space domain d′(x, t) and d′(y, t). Specifically, the inverse wavelet transform formula includes:

[0048]

[0049] In the formula, 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 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 (e.g., 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: 1 ′(x,t),d 2 ′(x,t),d 3 ′(x,t) and d 4 ′(x,t), the corresponding post-frequency division time-space domain signals within the four preset frequency bands are d 1 ′(y,t),d 2 ′(y,t),d 3 ′(y,t) and d 4 ′(y,t).

[0051] Specifically, in step S108, the P wave arrival time in the seismic record is selected as the reference signal, and the cross-correlation calculation is performed on the early frequency-divided time-space domain signal and the later 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 in the brackets takes the 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 four preset frequency bands, each frequency band corresponds to a data after matching the frequency division waveform: d 1 ′(x,t) c ,d 2 ′(x,t) c ,d 3 ′(x,t) c and d 4 ′(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. By taking advantage 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 the cross-correlation time-shift correction, the comparability and consistency of time-shift seismic data between seismic data collected in different times are ensured, the unexpected differences in non-oil and gas reservoir areas are eliminated, and the influence of time-shift seismic caused by changes in oil and gas reservoir fluids is highlighted. The technical problem that the two phases of data collected in the prior art are inconsistent in the non-reservoir area 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] Embodiment 2

[0059] In order to better carry out the potential research of a certain oil field, two three-dimensional acquisitions were carried out on the oil field, the early acquisition was offshore towed cable acquisition, and the later acquisition was OBC (Ocean Bottom Cable) acquisition. Non-repetitive time-lapse seismic consistency processing was carried out on the seismic data collected at different times and methods to eliminate the influence of environmental and human factors on the seismic data. The number of offshore towed cable acquisition cables is 4, the track spacing and cable spacing are 12.5 meters and 100 meters respectively, and the number of recording channels is 324 per cable; the number of OBC acquisition cables is 14, the track spacing and cable spacing are 25 meters and 200 meters respectively, and the number of recording channels is 240 per cable; the OBC acquisition method has relatively less shallow coverage; the towed cable has a narrow azimuth and uneven coverage; the shallow layer and the oil field more reflect the advantages of clear towed faults; the first and third sections of the middle and deep layers more reflect the characteristics of high coverage times, wide receiving azimuths, and high resolution of OBC data.

[0060] Figure 2 is a schematic diagram of a seismic profile of four-dimensional seismic data provided according to an embodiment of the present invention. Figure 2 As 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 preprocessed and transformed into four preset frequency bands, namely 5-10 Hz, 10-20 Hz, 20-30 Hz and 30-40 Hz, respectively. 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-divided streamer seismic profile provided in an embodiment of the present invention, wherein 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. Figure 4 It 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-space domain signal to obtain the following: Figure 5 The schematic diagram of the time-lapse streamer seismic profile is shown in Figure 1. Figure 5 The four cross-sectional diagrams from left to right in the schematic diagram correspond to the four preset frequency bands of 5-10 Hz, 10-20 Hz, 20-30 Hz and 30-40 Hz respectively. Figure 5 It can be seen that the method provided by the embodiment of the present invention can better solve the problem of consistency correction of the previous and next four-dimensional seismic data.

[0063] Embodiment 3

[0064] Figure 6 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, and 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 a plurality of 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 the frequency-divided waveform is matched.

[0070] The present invention further 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 invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0073] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description 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 may also be appropriately combined to form other implementation modes 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, and the early four-dimensional seismic data and the late four-dimensional seismic data are obtained 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 pre-frequency division data and the post-frequency division data respectively, to obtain pre-frequency division time-space domain signals and post-frequency division time-space domain signals within the multiple 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; The previous frequency-divided time-space domain signal is corrected based on the time offset to obtain data after frequency-divided waveform matching.

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

3. The method according to claim 1, characterized in that: The early four-dimensional seismic data and the late four-dimensional seismic data are respectively subjected to wavelet transform frequency division processing based on preset parameters, including: In the formula, 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 limits of the preset frequency band range respectively.

4. The method according to claim 3, characterized in that: The pre-frequency division data and the post-frequency division data are respectively subjected to inverse wavelet transformation based on the preset parameters, including: 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.

5. The method according to claim 4, characterized in that: 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.

6. The method according to claim 1, characterized in that: The previous frequency-divided time-space domain signal is corrected based on the time offset to obtain data after frequency-divided waveform matching, including: 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.

7. A four-dimensional seismic data correction system based on multi-scale frequency division waveform matching, characterized in that: include: Acquisition module, frequency division module, inverse transformation module, calculation module and 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, and obtain early four-dimensional seismic data and late four-dimensional seismic data respectively; 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 pre-frequency division data and the post-frequency division data, respectively, to obtain pre-frequency division time-space domain signals and post-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.

8. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method according to any one of claims 1 to 6 when executing the computer program.

9. 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 6 is implemented.

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