Pre-stack space residual amplitude compensation method for volcanic rock complex area

Abstract

The invention provides a volcanic rock complex area pre-stack space residual amplitude compensation method, and relates to the technical field of seismic post-stack data compensation. According to the method, the amplitude change rule of the target stratum is reflected through root mean square amplitude statistics of the igneous rock development area target stratum; after smoothing and normalization, abnormal root mean square amplitude attributes caused by bad traces and abnormal traces possibly existing in the seismic superposition data are eliminated; by extracting an amplitude compensation factor, obtaining a calculation factor which can be applied to the pre-stack CMP gather; the pre-stack space residual amplitude compensation of the volcanic rock complex area is realized, and the spatial amplitude consistency of a target layer is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of seismic post-stack data compensation, and particularly relates to a pre-stack spatial residual amplitude compensation method for complex volcanic rock areas. Background Technique

[0002] When seismic waves propagate underground, the amplitude will attenuate during the propagation process. The volcanic rock reflection interface is strong, and the wave impedance between interfaces is relatively large, which will seriously shield the reflection energy of the upper and lower strata. Moreover, due to the relatively complex geological structure, the seismic energy will change due to different geological structures. Especially at the interface of media, when the excited seismic waves propagate underground to the interface of media, due to the change of wave impedance, the amplitude of the particle vibration displacement changes, and the amplitude is distorted, which causes great difficulties in oil and gas exploration, seismic interpretation, and reservoir inversion.

[0003] Currently, the amplitude compensation methods mainly include spherical diffusion compensation based on the geometric diffusion theory and surface consistent amplitude compensation based on surface non-uniform absorption attenuation. These two amplitude compensation methods cannot solve the amplitude attenuation caused by the existence of complex volcanic rock areas underground, resulting in inconsistent spatial amplitudes between the volcanic rock development areas and non-volcanic rock development areas on the imaging profile.

[0004] In order to compensate the amplitude at the interface of media, Chinese invention patent CN108181649B discloses a method and device for compensating the amplitude at the interface of media, including: obtaining the root mean square amplitude value of a seismic trace according to the seismic data to be analyzed; picking up the interface of media, and calculating the interface reflection amplitude value corresponding to the interface of media according to the root mean square amplitude value of the seismic trace; calculating the interface transmission amplitude value corresponding to the interface of media according to the interface reflection amplitude value and the preset total seismic energy value by using A = Ar + At, where A represents the total seismic energy value, Ar represents the interface reflection amplitude value, and At represents the interface transmission amplitude value; calculating the interface amplitude compensation factor according to the interface transmission amplitude value by using St = As / At, where St represents the interface amplitude compensation factor, As represents the specified normalized amplitude level value, and At represents the interface transmission amplitude value; and performing the amplitude compensation operation of the interface of media according to the interface amplitude compensation factor and the root mean square amplitude value of the seismic trace. This compensation process reduces the phenomenon of uneven change in the amplitude strength characteristics at the interface of media, making the change in the amplitude strength of the compensated seismic data more natural.

[0005] Chinese Invention Patent CN115903044A discloses an energy absorption attenuation compensation method for strong shielding, including the steps of: S1, inputting denoised seismic data; S2, calculating the root mean square amplitude of the seismic data; S3, obtaining an exponential model of the attenuation of the seismic trace amplitude with time according to the root mean square amplitude value; S4, establishing a time window compensation function according to the exponential model to compensate the overall data. This invention calculates the attenuation coefficient by time window, and the obtained compensation function is variable in both time and space, which can reflect the characteristics of strong reflection interfaces such as igneous rocks and can well recover the attenuated energy of the strata above and below the igneous rocks.

[0006] However, the above compensation method does not set up a compensation method for the complex spatial residual amplitude of volcanic rocks, and moreover, it does not eliminate the abnormal root mean square amplitude attributes that may exist in the seismic stack data. It is not clear whether the consistency of the spatial amplitude of the complex spatial target layer is improved. Therefore, there is an urgent need for a spatial residual amplitude compensation method that can be applied to the complex volcanic rock area to achieve pre-stack spatial residual amplitude compensation in the complex volcanic rock area and improve the amplitude consistency of the target layer. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a pre-stack spatial residual amplitude compensation method for complex volcanic rock areas, which reflects the amplitude change law of the target layer by statistically analyzing the root mean square amplitude of the target layer in the igneous rock development area; eliminates the abnormal root mean square amplitude attributes caused by possible bad traces and abnormal traces in the seismic stack data after smoothing and normalization; obtains a calculation factor that can be applied to the pre-stack CMP gather by extracting the amplitude compensation factor; realizes pre-stack spatial residual amplitude compensation in complex areas, especially pre-stack spatial residual amplitude compensation in complex volcanic rock areas, and improves the spatial amplitude consistency of the target layer.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] On the one hand, the present invention provides a pre-stack spatial residual amplitude compensation method for complex areas, including the steps of:

[0010] S1. Based on the seismic data volume, statistically analyze the root mean square amplitude attribute of the target layer;

[0011] S2. Perform smoothing processing and normalization processing on the root mean square amplitude attribute of the target layer described in S1;

[0012] S3. Extract the residual amplitude compensation factor from the root mean square amplitude attribute after the normalization processing in S2;

[0013] S4. Use the residual amplitude compensation factor to perform amplitude compensation on the pre-stack gather to obtain the compensated pre-stack gather;

[0014] S5. Stack the obtained compensated pre-stack gathers.

[0015] Preferably, before performing step S1, seismic waves need to be collected to obtain a seismic data volume; the seismic data volume can be stacked to form a post-stack seismic data volume or a seismic stack data volume.

[0016] Preferably, in step S1, the root mean square amplitude attribute of the target layer in the development area is: the root mean square value of the amplitudes of the stacked section within a certain time window under the constraint of seismic horizon interpretation, to obtain the root mean square amplitude attribute of the target layer.

[0017] More preferably, for the determination of the time window range, specifically: based on the seismic stack section, pick up the formation interfaces according to the continuity of the event axes, and determine the time window range for statistics through the starting formation interface and the ending formation interface.

[0018] Preferably, in step S2, for the smoothing process, the smoothing grid size is taken as the maximum offset.

[0019] More preferably, the smoothing grid size is 7000×7000m.

[0020] Preferably, in step S2, the smoothing process is specifically: add the root mean square amplitude attributes of the target layer within the preset smoothing grid, and then divide by the number of seismic traces within the preset grid to obtain the smoothed amplitude value.

[0021] Preferably, in step S2, the normalization process is specifically: normalize the smoothed root mean square amplitude attribute according to the following formula: where A i is the normalized root mean square value; a i is the amplitude value after smoothing obtained in step S2; a max is the maximum amplitude value among the amplitude values after smoothing obtained in step S2.

[0022] Preferably, in step S3, the residual amplitude compensation factor is the magnitude of the normalized root mean square amplitude attribute.

[0023] Preferably, in step S3, the calculation formula of the residual amplitude compensation factor is P i =1 - A i , where P i is the extracted residual amplitude compensation factor.

[0024] Preferably, in step S4, the pre-stack gathers (CMP, Common Middle Point) include common shot gathers, common receiver gathers, and common reflection point gathers, and amplitude compensation of the residual amplitude compensation factor is performed on each CMP point in the pre-stack gathers.

[0025] Preferably, in step S4, the amplitude compensation and supplementation steps are specifically as follows: Each CMP point in the pre-stack gather corresponds to a residual amplitude compensation factor, and each pre-stack gather is multiplied by the corresponding residual amplitude compensation factor to obtain a compensated pre-stack gather.

[0026] More preferably, the amplitude compensation and compensation steps are specifically as follows:

[0027] S4-1: Determine a CMP point from the pre-stack gather;

[0028] S4-2: Multiply the CMP point determined in step S4-1 by the residual amplitude compensation factor obtained in the corresponding step S3 to obtain a compensated CMP point. The specific calculation formula is: M i =P i *C i , where M i is the compensated pre-stack CMP gather, and C i is the pre-stack gather;

[0029] S4-3: Traverse the pre-stack gather and repeat steps S4-1 and S4-2 to obtain all compensated CMP gathers.

[0030] On the other hand, the present invention provides an application of the above method in detecting the pre-stack spatial amplitude in a complex area.

[0031] Then, the present invention also provides the residual amplitude compensation factor established by the above method.

[0032] Finally, the present invention also provides an application of the above residual amplitude compensation factor in the pre-stack gather and / or detecting the spatial amplitude of volcanic rocks.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] In the method of the present invention, by statistically analyzing the root mean square amplitude attribute of the target layer in the complex area, and then smoothing and normalizing the plane attribute for spatial anti-compensation of the pre-stack gather, calculating the residual amplitude compensation factor, and applying it to the pre-stack gather, the spatial amplitude consistency of the target layer is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a flowchart of the pre-stack spatial residual amplitude compensation method for the complex area described in the present invention.

[0036] Figure 2 is a schematic diagram of the seismic stacking data volume in Embodiment 1 of the present invention.

[0037] Figure 3 is a schematic diagram of the root mean square amplitude attribute of the target layer before compensation.

[0038] Figure 4 It is a schematic diagram of the root mean square amplitude attribute of the target layer after adopting the method described in the present invention. Specific implementation manners

[0039] The following non-limiting embodiments can enable those of ordinary skill in the art to more comprehensively understand the present invention, but do not limit the present invention in any way. The following content is only an exemplary illustration of the scope claimed by the present invention. Those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and it should also fall within the scope claimed by the present invention. When an embodiment gives a numerical range, it should be understood that unless otherwise specified in the present invention, any value at both ends of each numerical range and any value between the two ends can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The present invention will be further described below by way of specific embodiments.

[0040] Embodiment 1

[0041] Step S1: Based on the seismic stack data volume, the root mean square amplitude attribute of the target layer in the volcanic rock development area is statistically obtained. The root mean square amplitude attribute of the target layer in the volcanic rock development area is the root mean square value of the amplitude of the stacked section within a certain time window under the constraint of seismic horizon interpretation.

[0042] The root mean square amplitude attribute of the target layer is specifically obtained by the following steps:

[0043] The seismic single-shot data is collected by using a collection device, and after conventional seismic data processing and stacking, a seismic stack data volume is obtained, as Figure 2 shown. Multiple attributes such as the amplitude, energy, phase, and frequency of the seismic stack data volume are closely related to reservoir physical properties, hydrocarbon-bearing relationships, and sedimentary characteristics. The range of the igneous rock development area is determined on the seismic stack data volume through drilling and geological understanding, as Figure 2 the ranges outlined by the red line and the blue line. The amplitude values of the seismic stack data volume within this range are statistically obtained, and the root mean square value is calculated to obtain the root mean square amplitude attribute of the target layer, as Figure 3 shown.

[0044] The stratigraphic interface is the dividing line of sediments with different physical properties underground. The dividing line divides the sediments with similar physical properties together and separates the sediments with significantly different physical properties. Therefore, by adding the constraint of the horizon in the seismic-driven modeling process, stratigraphic modeling can be carried out, that is, a formation space conversion function is obtained for each horizon, and the description of the change of formation physical property parameters by the calculated formation space conversion function will be more accurate. Only the formation space conversion function obtained for a certain horizon is used within that horizon to estimate the physical property parameters within that horizon.

[0045] In this embodiment, the determination of the time window range is specifically as follows: The time window range for calculating the root mean square value of the statistical amplitude is determined through step S1. First, based on the seismic stack profile and the continuity of the event axis, the formation interfaces are picked up. Figure 2 The red line and the blue line in the figure represent two different formation interfaces. Then, with the red line as the starting point and the blue line point as the ending point, the statistical time window range is determined.

[0046] Step S2: Smooth and normalize the root mean square amplitude attribute of the target layer in step S1. Among them, the smoothing grid size is taken as the maximum offset in the work area, and in this embodiment, it is taken as 7000m × 7000m.

[0047] The root mean square amplitude attribute statistically calculated in step S1 is the root mean square value within a fixed time window for each trace of the seismic stack profile. Since there are bad traces and abnormal traces in the seismic stack profile, it will cause calculation errors in calculating the amplitude compensation factor during the normalization process. Therefore, it is necessary to smooth and normalize the root mean square amplitude attribute of the target layer. The specific process is as follows:

[0048] Step S2-1: Smooth the root mean square amplitude attribute of the target layer, that is, add the amplitude values within the preset horizontal grid (7000m × 7000m) of the root mean square amplitude attribute of the target layer, and then divide by the number of seismic traces within the preset grid to obtain the smoothed amplitude value.

[0049] Step S2-2: Normalize the smoothed root mean square amplitude attribute. The specific formula for the normalization process is as follows: Among them, A i is the root mean square value after normalization; a i is the smoothed amplitude value obtained in step S21; a max is the maximum amplitude value among the smoothed amplitude values obtained in step S21.

[0050] Step S3: Extract the remaining amplitude compensation factor from the normalized root mean square amplitude attribute; the extracted remaining amplitude compensation factor is the magnitude of the normalized root mean square amplitude attribute.

[0051] In this embodiment, the remaining amplitude compensation factor is calculated through the following formula:

[0052] P i = 1 - A i where P i is the extracted remaining amplitude compensation factor.

[0053] Step S4: Perform amplitude compensation on the pre-stack gather (CMP, Common Middle Point) using the remaining amplitude compensation factor; the specific compensation method is as follows: Each CMP point in the pre-stack gather corresponds to a remaining amplitude compensation factor, and each pre-stack gather is multiplied by the corresponding remaining amplitude compensation factor to obtain the compensated pre-stack gather.

[0054] The pre-stack gather includes the common shot gather, the common receiver gather, and the common reflection point gather. Performing the compensation of the remaining amplitude compensation factor on each CMP point in the pre-stack gather specifically includes:

[0055] Step S4-1: Determine a CMP point from the pre-stack gather;

[0056] Step S4-2: Multiply the CMP point determined in Step S4-1 by the remaining amplitude compensation factor obtained in the corresponding Step S3 to obtain the compensated CMP point. The specific calculation formula is: M i = P i * C i , where M i is the compensated pre-stack CMP gather, and C i is the pre-stack gather.

[0057] Step S4-3: Traverse the pre-stack gather and repeat Steps S4-1 and S4-2 to obtain all compensated CMP gathers.

[0058] Step S5: Perform stacking processing on all the obtained compensated pre-stack gathers.

[0059] Before performing the above compensation method, the root mean square amplitude attribute before compensation obtained shows that the consistency of the spatial amplitude of the target layer is weak; after the operation of the compensation method described in the present invention, the consistency of the spatial amplitude of the target layer is improved, as Figure 3 shown. Figure 4 shown.

[0060] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than a limitation on the protection scope of the present invention. Any simple modification or equivalent replacement of the technical solution of the present invention by those of ordinary skill in the art does not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A pre-stack spatial residual amplitude compensation method for complex areas, characterized in that, Including the steps: S1. Based on the seismic data volume, statistically calculate the root-mean-square amplitude attribute of the target layer in the development area; S2. Smooth and normalize the root-mean-square amplitude attribute of the target layer described in S1; S3. Extract the residual amplitude compensation factor from the root-mean-square amplitude attribute after the normalization process in S2; S4. Use the residual amplitude compensation factor to perform amplitude compensation on the pre-stack gather to obtain the compensated pre-stack gather; S5. Perform stacking processing on the obtained compensated pre-stack gather.

2. The method according to claim 1, characterized in that, Before performing step S1, it is necessary to collect seismic waves to obtain a seismic data volume; the seismic data volume can be stacked to form a post-stack seismic data volume or a seismic stacked data volume.

3. The method according to claim 1, characterized in that, In step S1, the root-mean-square amplitude attribute of the target layer in the development area is: the root-mean-square value of the amplitude of the stacked section within a certain time window under the constraint of seismic horizon interpretation, to obtain the root-mean-square amplitude attribute of the target layer.

4. The method according to claim 3, characterized in that For the determination of the time window range, the specific determination method is: based on the seismic stacked section, pick up the formation interface according to the continuity of the event axis, and determine the time window range for statistics through the starting formation interface and the ending formation interface.

5. The method according to claim 1, characterized in that, In step S2, for the smoothing process, the smoothing grid size takes the maximum offset; the smoothing process is specifically: add the root-mean-square amplitude attributes of the target layer within the preset smoothing grid, and then divide by the number of seismic traces within the preset grid to obtain the smoothed amplitude value.

6. The method according to claim 1, wherein In step S2, the normalization process is specifically as follows: the smoothed root mean square amplitude attribute is normalized according to the following formula: where A i is the root mean square value after normalization; a i is the amplitude value obtained after smoothing in step S2; a max is the maximum amplitude value among the amplitude values obtained after smoothing in step S2.

7. The method according to claim 1, characterized in that, In step S3, the remaining amplitude compensation factor is the magnitude of the root mean square amplitude attribute after normalization; the calculation formula for the remaining amplitude compensation factor is P i = 1 - A i , where P i is the extracted remaining amplitude compensation factor.

8. The method according to claim 1, wherein In step S4, the pre-stack gather includes a common shot gather, a common receiver gather, and a common reflection point gather; perform amplitude compensation of the residual amplitude compensation factor on each CMP point in the pre-stack gather.

9. The method according to claim 1, characterized in that, In step S4, the amplitude compensation supplementary steps are specifically: each CMP point in the pre-stack gather corresponds to a residual amplitude compensation factor, and each pre-stack gather is multiplied by the corresponding residual amplitude compensation factor to obtain the compensated pre-stack gather.

10. The method according to claim 9, wherein The amplitude compensation supplementary steps are specifically: S4-1: Determine a CMP point from the pre-stack gather; S4-2: Multiply the CMP points determined in step S4-1 by the remaining amplitude compensation factor obtained in the corresponding step S3 to obtain the compensated CMP points. The specific calculation formula is: M i = P i * C i , where M i is the pre-stack CMP gather after compensation, and C i is the pre-stack gather; S4-3: Traverse the pre-stack gather, repeat steps S4-1 and S4-2 to obtain all compensated CMP gathers.

11. Application of the method according to any one of claims 1-10 in detecting the pre-stack spatial amplitude in a complex area.

12. Residual amplitude compensation factor established by the method according to any one of claims 1-10.

13. Application of the residual amplitude compensation factor according to claim 12 in a pre-stack gather and / or in detecting the spatial amplitude of volcanic rocks.

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