Five-dimensional seismic gather leveling correction method and device based on two-step method

Abstract

The invention discloses a five-dimensional seismic gather leveling correction method and device based on a two-step method. The method comprises the following steps: acquiring a relative leveling gather of a plurality of five-dimensional seismic gathers; based on the relative leveling gather, calculating to obtain a final leveling gather; and repeating the steps for multiple times to finish the leveling correction of the five-dimensional seismic trace gather data volume. According to the method, correlation is carried out on each channel in a gather and an adjacent channel to calculate the relative time difference of the gather, correction is carried out by calculating the residual time difference of each channel and the adjacent channel, leveling correction processing and event leveling are carried out on gather data, and it is ensured that no stretching distortion exists while second-class OVT characteristics are reserved.

Description

Technical Field

[0001] The present invention relates to the field of physical exploration technology, and in particular to a five-dimensional seismic gather leveling correction method and device based on a two-step method. Background Art

[0002] At present, oil and gas exploration in the oil fields of eastern China has entered the middle and late stages, and large-scale structural oil and gas reservoirs have been exhausted. Small-scale lithological and concealed oil and gas reservoirs have become the focus of current exploration and development. From the perspective of technological development, the technical direction of onshore oil and gas seismic exploration is single-source, single-detection, high-density and wide-azimuth seismic data acquisition and imaging processing technology. At present, the international specialized technology for wide-azimuth five-dimensional seismic data processing is mainly OVT processing technology. OVT (Offset Vector Tile) is usually translated as "shot offset vector tile technology", which was first proposed by Vermeer when studying the minimum data set expression of the acquisition area; Cary almost independently proposed the concept of common shot offset vector COV (Common Offset Vector) at the same time.

[0003] In seismic data processing, stacking is an effective denoising method. However, in actual OVT seismic data processing, the dynamic correction velocity is based on the NMO algorithm with flat layer assumption, and it is the interpolation velocity of discrete points, which is difficult to calculate accurately; in addition, due to the time difference caused by velocity anisotropy, when there is an inhomogeneous body in the seismic ray path, even the prestack time migration algorithm cannot obtain the flattened gather. Therefore, there will be a certain amount of residual dynamic correction on the data after dynamic correction, which will reduce the resolution of the stacked section when doing in-phase stacking.

[0004] The commonly used flattening method is to use the near-track stacking as the reference track, and compare and flatten the remaining tracks with the reference track. Since the correlation between the far track and the near track of the five-dimensional seismic is poor, distortion and stretching are easily produced. Summary of the invention

[0005] In view of the above technical problems in the related art, the present invention proposes a five-dimensional seismic gather flattening correction method and device based on a two-step method, which can overcome the above shortcomings of the prior art.

[0006] To achieve the above technical objectives, the technical solution of the present invention is implemented as follows:

[0007] On the one hand, a five-dimensional seismic gather leveling correction method based on a two-step method is provided, comprising:

[0008] Obtain relatively flattened gathers of multiple 5D seismic gathers;

[0009] Based on the relatively flattened gathers, the final flattened gathers are calculated;

[0010] Repeat the above steps several times to complete the flattening correction of the five-dimensional seismic gather data volume.

[0011] Furthermore, the step of obtaining a relatively flattened gather of a five-dimensional seismic gather includes:

[0012] Obtaining a first five-dimensional seismic spiral gather from a five-dimensional seismic data volume;

[0013] According to the spiral arrangement order of the first five-dimensional seismic gather, the current trace is sequentially compared with the previous trace to calculate the relative time shift;

[0014] The relative time shifts of all the tracks before the current track are accumulated and added together to obtain the absolute time shift of the current track.

[0015] The time shift is performed according to the absolute time shift of the current trace to obtain the relatively flattened gather of the five-dimensional seismic gather.

[0016] Furthermore, the calculation of the final flattened gather based on the relatively flattened gather includes:

[0017] Based on the relative flattened gathers and the reference traces, the residual time shift is calculated, and the residual flattened gathers of the relative time shift are calculated to obtain the final flattened gathers.

[0018] Further, the calculation of the residual time shift based on the relatively flattened gathers and the reference traces includes:

[0019] Based on the relatively flattened trace gathers, the near traces are added as the reference traces, and the remaining traces are compared with the reference traces to calculate the residual time shift.

[0020] Furthermore, the relative time shifts of all tracks before the current track are accumulated and added together to obtain the calculation formula for the absolute time shift of the current track:

[0021]

[0022] In the formula, Δτ j is the relative time shift between the current trace and the previous trace, τ i is the absolute time shift of the current track.

[0023] On the other hand, a five-dimensional seismic gather flattening correction device based on a two-step method is provided, comprising:

[0024] An acquisition module, used for acquiring relatively flattened gathers of multiple five-dimensional seismic gathers;

[0025] A calculation module, used for calculating the final flattened gather based on the relatively flattened gather;

[0026] The correction module is used to repeat the above steps multiple times to complete the flattening correction of the five-dimensional seismic gather data volume.

[0027] Furthermore, the step of obtaining a relatively flattened gather of a five-dimensional seismic gather includes:

[0028] Obtaining a first five-dimensional seismic spiral gather from a five-dimensional seismic data volume;

[0029] According to the spiral arrangement order of the first five-dimensional seismic gather, the current trace is sequentially compared with the previous trace to calculate the relative time shift;

[0030] The relative time shifts of all the tracks before the current track are accumulated and added together to obtain the absolute time shift of the current track.

[0031] The time shift is performed according to the absolute time shift of the current trace to obtain the relatively flattened gather of the five-dimensional seismic gather.

[0032] Furthermore, the calculation of the final flattened gather based on the relatively flattened gather includes:

[0033] Based on the relative flattened gathers and the reference traces, the residual time shift is calculated, and the residual flattened gathers of the relative time shift are calculated to obtain the final flattened gathers.

[0034] Further, the calculation of the residual time shift based on the relatively flattened gathers and the reference traces includes:

[0035] Based on the relatively flattened trace gathers, the near traces are added as the reference traces, and the remaining traces are compared with the reference traces to calculate the residual time shift.

[0036] Furthermore, the relative time shifts of all tracks before the current track are accumulated and added together to obtain the calculation formula for the absolute time shift of the current track:

[0037]

[0038] In the formula, Δτ j is the relative time shift between the current trace and the previous trace, τ i is the absolute time shift of the current track.

[0039] The beneficial effects of the present invention are as follows: the present invention calculates the relative time difference of the gather by correlating each channel with the adjacent channels, and uses the residual time difference between each channel and the near channel to correct the calculated time difference, performs flattening correction processing on the gather data, flattens the event axis, and ensures that there is no stretching distortion while retaining the second type of OVT characteristics; while ensuring the flattening of the event axis of the five-dimensional seismic gather, while retaining the second type of OVT characteristics, ensures that there is no stretching distortion, eliminates the time difference caused by the velocity anisotropy of the five-dimensional seismic data, restores the anisotropic characteristics of the amplitude, and ensures the correctness and effectiveness of the five-dimensional seismic data in anisotropic fracture detection and oil and gas identification; the present invention proposes a two-step flattening method, which not only overcomes the cumulative error of the adjacent channel flattening, but also eliminates the stretching distortion caused by the near and far channels, ensures the high-precision distortion-free five-dimensional seismic flattening effect, and enables the five-dimensional seismic to truly play its advantages in anisotropic fracture identification and fluid prediction. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 is a flow chart of a five-dimensional seismic gather flattening correction method based on a two-step method according to an embodiment of the present invention;

[0042] Figure 2 To obtain a five-dimensional seismic gather from the entire five-dimensional seismic gather data volume using the embodiment of the present invention;

[0043] Figure 3 A schematic diagram of calculating relative time difference and leveling each track in a solution using an embodiment of the present invention;

[0044] Figure 4 A schematic diagram of calculating the absolute time difference flattening using the solution of an embodiment of the present invention;

[0045] Figure 5 A five-dimensional seismic flattened trace gather is obtained using the solution of an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the accompanying 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 belong to the scope of protection of the present invention.

[0047] like Figure 1-5 As shown: A five-dimensional seismic gather leveling correction method based on a two-step method is provided, including:

[0048] Obtain relatively flattened gathers of multiple 5D seismic gathers;

[0049] Based on the relatively flattened gathers, the final flattened gathers are calculated;

[0050] Repeat the above steps several times to complete the flattening correction of the five-dimensional seismic gather data volume.

[0051] In some embodiments of the present invention, the step of obtaining a relatively flattened gather of a five-dimensional seismic gather comprises:

[0052] Obtaining a first five-dimensional seismic spiral gather from a five-dimensional seismic data volume;

[0053] According to the spiral arrangement order of the first five-dimensional seismic gather, the current trace is sequentially compared with the previous trace to calculate the relative time shift;

[0054] The relative time shifts of all the tracks before the current track are accumulated and added together to obtain the absolute time shift of the current track.

[0055] The time shift is performed according to the absolute time shift of the current trace to obtain the relatively flattened gather of the five-dimensional seismic gather.

[0056] In some embodiments of the present invention, the step of calculating the final flattened gather based on the relatively flattened gather comprises:

[0057] Based on the relative flattened gathers and the reference traces, the residual time shift is calculated, and the residual flattened gathers of the relative time shift are calculated to obtain the final flattened gathers.

[0058] In some embodiments of the present invention, the calculation of the residual time shift based on the relatively flattened gathers and the reference traces includes:

[0059] Based on the relatively flattened trace gathers, the near traces are added as the reference traces, and the remaining traces are compared with the reference traces to calculate the residual time shift.

[0060] In some embodiments of the present invention, the calculation formula for accumulating and adding the relative time shifts of all tracks before the current track to obtain the absolute time shift of the current track is:

[0061]

[0062] In the formula, Δτ j is the relative time shift between the current trace and the previous trace, τ i is the absolute time shift of the current track.

[0063] On the other hand, a five-dimensional seismic gather flattening correction device based on a two-step method is provided, comprising:

[0064] An acquisition module, used for acquiring relatively flattened gathers of multiple five-dimensional seismic gathers;

[0065] A calculation module, used for calculating the final flattened gather based on the relatively flattened gather;

[0066] The correction module is used to repeat the above steps multiple times to complete the flattening correction of the five-dimensional seismic gather data volume.

[0067] In some embodiments of the present invention, the step of obtaining a relatively flattened gather of a five-dimensional seismic gather comprises:

[0068] Obtaining a first five-dimensional seismic spiral gather from a five-dimensional seismic data volume;

[0069] According to the spiral arrangement order of the first five-dimensional seismic gather, the current trace is sequentially compared with the previous trace to calculate the relative time shift;

[0070] The relative time shifts of all the tracks before the current track are accumulated and added together to obtain the absolute time shift of the current track.

[0071] The time shift is performed according to the absolute time shift of the current trace to obtain the relatively flattened gather of the five-dimensional seismic gather.

[0072] In some embodiments of the present invention, the step of calculating the final flattened gather based on the relatively flattened gather comprises:

[0073] Based on the relative flattened gathers and the reference traces, the residual time shift is calculated, and the residual flattened gathers of the relative time shift are calculated to obtain the final flattened gathers.

[0074] In some embodiments of the present invention, the calculation of the residual time shift based on the relatively flattened gathers and the reference traces includes:

[0075] Based on the relatively flattened trace gathers, the near traces are added as the reference traces, and the remaining traces are compared with the reference traces to calculate the residual time shift.

[0076] In some embodiments of the present invention, the calculation formula for accumulating and adding the relative time shifts of all tracks before the current track to obtain the absolute time shift of the current track is:

[0077]

[0078] In the formula, Δτ j is the relative time shift between the current trace and the previous trace, τ i is the absolute time shift of the current track.

[0079] Reference Figure 1 As shown, a five-dimensional seismic gather flattening correction method based on a two-step method in this embodiment has the following specific steps:

[0080] S10. Obtain a five-dimensional seismic gather from the entire five-dimensional seismic gather data volume. Figure 2 It is a 5D seismic gather from a 5D seismic work area in the Bohai Bay Basin. From the whole gather, especially the anisotropic time difference at 2450ms, that is, the gather is curved and uneven, which will destroy the anisotropic characteristics of the amplitude and the relationship between the amplitude and the offset, affecting the fracture identification and oil and gas prediction. It needs to be flattened under the premise of ensuring no distortion.

[0081] S20, according to the spiral arrangement order of the five-dimensional seismic gathers, the current trace is compared with the previous trace in turn, and the relative time shift is calculated, such as Figure 3 As shown, the relative time shift of the second track to the first track is calculated, the relative time shift of the third track to the second track is calculated, and the relative time shift of all tracks is calculated in sequence. Since the signal characteristics of adjacent tracks are basically the same, there will be no distortion error.

[0082] S30, the relative time shifts of all tracks preceding the current track are cumulatively added to obtain the absolute time shift of the current track; the absolute time shift of the current track is obtained by using the following formula:

[0083]

[0084] In the formula, Δτ j is the relative time shift between the current trace and the previous trace, τ i is the absolute time shift of the current track.

[0085] like Figure 3 As shown, the absolute time shift of the 4th track is the accumulation of the time shifts of the 2nd, 3rd and 4th tracks.

[0086] S40. Time shift is performed according to the absolute time shift of the current track to obtain the first step of the relatively flattened track gather. Although there is no distortion error in the calculation of the relative time shift, there are slight errors due to the influence of factors such as noise. The five-dimensional seismic track gather has a large number of tracks, so there is often a large cumulative error.

[0087] S50, based on the relative flattened gather, the near traces are added as the reference traces, the remaining traces are correlated with the reference traces, the residual time shift is calculated, and the second step of residual flattening is performed to eliminate the accumulated error in the first step of flattening, and the final flattened gather is obtained. Figure 3 It is a schematic diagram for calculating the absolute time difference and leveling. The 1st to 4th tracks are superimposed as the leveling reference track, and the remaining tracks are aligned and leveled to the reference track.

[0088] S60. Repeat steps S10 to S50 to process the flattened data volume of the five-dimensional seismic gathers in the entire work area.

[0089] Here is Figure 2Repeat steps S20 to S50 for a five-dimensional seismic gather as shown in FIG. Figure 5 As shown, Figure 2 Compared to that, Figure 5 Not only the residual time difference is eliminated, but also there is no distortion phenomenon, and the five-dimensional seismic amplitude changes significantly with the azimuth and offset, which shows that the method of the present invention has a good leveling effect and ensures that the five-dimensional seismic data is authentic and valid.

[0090] In some embodiments of the present invention, first, a five-dimensional seismic spiral gather is obtained from a five-dimensional seismic data body; then, according to the spiral arrangement order of the five-dimensional seismic gather, the current track is sequentially compared with the previous track to calculate the relative time shift; then, the relative time shifts of all tracks in front of the current track are cumulatively added to obtain the absolute time shift of the current track; secondly, time shift is performed according to the absolute time shift of the current track to obtain the first step of the relative flattened gather; finally, based on the relative flattened gather, the near track is added as the reference track, and the remaining tracks are correlated with the reference track to calculate the residual time shift, and the second step of residual flattening is performed to obtain the final flattened gather. Compared with the prior art, the present invention, for five-dimensional seismic gathers, not only overcomes the problem that the near and far track signals are relatively different and the far track cannot be aligned with the near track; at the same time, it overcomes the problem that the relative flattening cumulative error is large due to the large number of tracks and low signal-to-noise ratio in the five-dimensional seismic gather. The two-step flattening method is a reliable method for flattening five-dimensional seismic gathers, providing correct data for five-dimensional seismic fracture detection and oil and gas prediction.

[0091] In summary, the present invention correlates each track in the gather with the adjacent track to calculate the relative time difference of the gather, and uses the residual time difference between each track and the near track to correct it, and performs flattening correction processing on the gather data, flattens the event axis, and ensures that there is no stretching distortion while retaining the second type of OVT characteristics; while ensuring the flattening of the event axis of the five-dimensional seismic gather, while retaining the second type of OVT characteristics, ensures that there is no stretching distortion, eliminates the time difference caused by velocity anisotropy of the five-dimensional seismic data, restores the anisotropic characteristics of the amplitude, and ensures the correctness and effectiveness of the five-dimensional seismic data in anisotropic fracture detection and oil and gas identification; the present invention proposes a two-step flattening method, which not only overcomes the cumulative error of adjacent track flattening, but also eliminates the stretching distortion caused by near and far tracks, and ensures a high-precision distortion-free five-dimensional seismic flattening effect, so that the five-dimensional seismic can truly play its advantages in anisotropic fracture identification and fluid prediction.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A five-dimensional seismic gather leveling correction method based on a two-step method, characterized in that: include: Obtain relatively flattened gathers of multiple 5D seismic gathers; Based on the relatively flattened gathers, the final flattened gathers are calculated; Repeat the above steps several times to complete the flattening correction of the five-dimensional seismic gather data volume.

2. A five-dimensional seismic gather flattening correction method based on a two-step method according to claim 1, characterized in that: The step of obtaining a relatively flattened gather of a five-dimensional seismic gather comprises: Obtaining a first five-dimensional seismic spiral gather from a five-dimensional seismic data volume; According to the spiral arrangement order of the first five-dimensional seismic gather, the current trace is sequentially compared with the previous trace to calculate the relative time shift; The relative time shifts of all the tracks before the current track are accumulated and added together to obtain the absolute time shift of the current track. The time shift is performed according to the absolute time shift of the current trace to obtain the relatively flattened gather of the five-dimensional seismic gather.

3. A five-dimensional seismic gather flattening correction method based on a two-step method according to claim 2, characterized in that: The method of calculating the final flattened gather based on the relatively flattened gather includes: Based on the relative flattened gathers and the reference traces, the residual time shift is calculated, and the residual flattened gathers of the relative time shift are calculated to obtain the final flattened gathers.

4. The five-dimensional seismic gather flattening correction method based on the two-step method according to claim 3, characterized in that: The method of calculating the residual time shift based on the relatively flattened gathers and the reference traces includes: Based on the relatively flattened trace gathers, the near traces are added as the reference traces, and the remaining traces are compared with the reference traces to calculate the residual time shift.

5. The five-dimensional seismic gather flattening correction method based on the two-step method according to claim 2, characterized in that: The calculation formula for accumulating and adding the relative time shifts of all the tracks before the current track to obtain the absolute time shift of the current track is: In the formula, Δτ j is the relative time shift between the current trace and the previous trace, τ i is the absolute time shift of the current track.

6. A five-dimensional seismic gather leveling correction device based on a two-step method, characterized in that: include: An acquisition module, used for acquiring relatively flattened gathers of multiple five-dimensional seismic gathers; A calculation module, used for calculating the final flattened gather based on the relatively flattened gather; The correction module is used to repeat the above steps multiple times to complete the flattening correction of the five-dimensional seismic gather data volume.

7. The five-dimensional seismic gather flattening correction device based on the two-step method according to claim 6, characterized in that: The step of obtaining a relatively flattened gather of a five-dimensional seismic gather comprises: Obtaining a first five-dimensional seismic spiral gather from a five-dimensional seismic data volume; According to the spiral arrangement order of the first five-dimensional seismic gather, the current trace is sequentially compared with the previous trace to calculate the relative time shift; The relative time shifts of all the tracks before the current track are accumulated and added together to obtain the absolute time shift of the current track. The time shift is performed according to the absolute time shift of the current trace to obtain the relatively flattened gather of the five-dimensional seismic gather.

8. The five-dimensional seismic gather flattening correction device based on the two-step method according to claim 7, characterized in that: The method of calculating the final flattened gather based on the relatively flattened gather includes: Based on the relative flattened gathers and the reference traces, the residual time shift is calculated, and the residual flattened gathers of the relative time shift are calculated to obtain the final flattened gathers.

9. The five-dimensional seismic gather flattening correction device based on the two-step method according to claim 8, characterized in that: The method of calculating the residual time shift based on the relatively flattened gathers and the reference traces includes: Based on the relatively flattened trace gathers, the near traces are added as the reference traces, and the remaining traces are compared with the reference traces to calculate the residual time shift.

10. The five-dimensional seismic gather flattening correction device based on the two-step method according to claim 7, characterized in that: The calculation formula for accumulating and adding the relative time shifts of all the tracks before the current track to obtain the absolute time shift of the current track is: In the formula, Δτ j is the relative time shift between the current trace and the previous trace, τ i is the absolute time shift of the current track.

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