Three-dimensional seismic exploration method

Abstract

The invention discloses a three-dimensional seismic exploration method, which belongs to the technical field of exploration, and comprises the following steps: laying a measuring network; blasting is conducted; collecting and processing data; original data collected by a detector and a seismograph is subjected to decompilation, spatial attribute definition, channel editing, first arrival pickup, tomographic static correction, true amplitude recovery, band-pass filtering, earth surface consistency prediction deconvolution, velocity analysis, three-dimensional residual static correction, frequency and spatial domain random noise attenuation, three-dimensional channel interpolation, one-step method three-dimensional time migration and band-pass filtering. Carrying out amplitude equalization, and outputting an offset data body; and completing three-dimensional seismic exploration. According to the invention, the original data acquisition and processing quality is high, an advanced processing system is selected, a data volume with a high signal-to-noise ratio, high resolution and high fidelity is obtained, all known geological and geophysical prospecting data in a region are integrated to carry out fine comparison, analysis and explanation on seismic data, a geological result with high quality is obtained, and the geological prospecting effect is good. And detailed geological basic data are provided for later mine production.

Description

Technical Field

[0001] The present invention relates to the technical field of exploration, and particularly to a three-dimensional seismic exploration method. Background Art

[0002] In seismic exploration in complex surface areas, due to large differences in regional terrain and variable near-surface lithology, seismic exploration is difficult, data acquisition is difficult, signal-to-noise ratio is low, static correction is difficult, velocity analysis and imaging are difficult. Especially in complex exploration areas in the western region, restricted by geomorphology and construction conditions, it is difficult to reach, resulting in missing channels and shots, or unsatisfactory shot positions, thus affecting the quality of data acquisition.

[0003] To solve the above problems, the present invention provides a three-dimensional seismic exploration method to solve the problem of low exploration efficiency in the past. Summary of the Invention

[0004] The object of the present invention is to provide a three-dimensional seismic exploration method to achieve the purpose of improving the seismic exploration effect.

[0005] To achieve the above object, the present invention provides the following solution:

[0006] A three-dimensional seismic exploration method includes the following steps:

[0007] Survey network layout; adopting a 10-line 10-shot beam observation system, with the receiving lines arranged perpendicular to the stratigraphic strike;

[0008] Shot firing;

[0009] Data acquisition and processing: using geophones and seismographs to collect data; decoding the original data collected by geophones and seismographs, defining spatial attributes, channel editing, first arrival picking, tomographic static correction, true amplitude recovery, band-pass filtering, surface-consistent predictive deconvolution, common midpoint gather, velocity analysis, three-dimensional residual static correction, DMO correction, frequency and spatial domain random noise attenuation, three-dimensional in-line interpolation, one-step three-dimensional time migration, band-pass filtering, amplitude equalization, and outputting a standard SEGY format migrated data volume;

[0010] Completion of three-dimensional seismic exploration.

[0011] Preferably, the distance between receiving lines is 40 meters, the longitudinal coverage is 7 times, and the lateral coverage is 5 times.

[0012] Preferably, the geophone is a 7Hz geophone, the seismograph is a 428XL high-resolution digital seismograph, the sampling interval is 0.5ms, the recording length is 2s, the recording format is SEG-D, and the preamplification gain is 12db.

[0013] Preferably, the spatial attribute definition is to accurately establish shot points and geophone points and draw an accurate position map of shot points and geophone points.

[0014] Preferably, the trace editing is to eliminate abnormal traces and suppress noise.

[0015] Preferably, the frequency and spatial domain random noise attenuation method is selected as follows: for outliers and abnormal amplitudes, the cross-frequency abnormal amplitude suppression method is adopted; for surface waves, the adaptive surface wave attenuation technology and regional filtering technology are adopted.

[0016] Preferably, the surface consistent predictive deconvolution technology is applied to correct the seismic wavelet, eliminate the influence of surface inconsistent factors on the seismic wavelet, and then, on the basis of residual static correction, perform predictive deconvolution to further compress the wavelet and improve the vertical resolution.

[0017] Preferably, the DMO correction, namely dip moveout correction, is to first migrate the data after normal moveout to zero offset and then stack it.

[0018] Preferably, the migration velocity of the one-step migration is obtained by calibrating the DMO velocity with boreholes.

[0019] The present invention has achieved the following technical effects compared with the prior art:

[0020] The quality of the original data acquisition and processing of the present invention is relatively high. An advanced processing system is selected to obtain a data volume with high signal-to-noise ratio, high resolution, and high fidelity. All known geological and geophysical data in the area are comprehensively used to conduct fine comparison, analysis, and interpretation of the seismic data, and high-quality geological results are obtained, providing detailed geological basic data for the later mine production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 is the data acquisition and processing flow chart of the present invention;

[0023] Figure 2 is the coverage times map of the CDP grid 10×10 observation system of the present invention;

[0024] Figure 3 is the rose diagram of the CDP grid 10×10 observation system of the present invention;

[0025] Figure 4 is the single-shot comparison before and after amplitude recovery of the present invention;

[0026] Figure 5Single-shot comparison before and after denoising for the present invention;

[0027] Figure 6 Spectrum schematic diagrams before and after deconvolution for the present invention;

[0028] Figure 7 Single-shot record comparison diagrams before and after deconvolution for the present invention;

[0029] Figure 8 Section comparison before and after residual statics correction for the present invention;

[0030] Figure 9 Section comparison before and after migration for the present invention;

[0031] Figure 10 10×10 CDP grid acquisition system for the present invention; Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] The purpose of the present invention is to provide a three-dimensional seismic exploration method to achieve the purpose of improving the seismic exploration effect.

[0034] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0035] Refer to Figure 1 , a three-dimensional seismic exploration method, including the following steps: survey network layout; using a 10-line 10-shot beam acquisition system, with the receiving lines arranged perpendicular to the formation strike; shooting; data acquisition and processing: using geophones and seismographs to collect data; decoding the original data collected by the geophones and seismographs, defining spatial attributes, trace editing, first arrival picking, tomographic statics correction, true amplitude recovery, band-pass filtering, surface-consistent predictive deconvolution, common midpoint gather, velocity analysis, three-dimensional residual statics correction, DMO correction, frequency and spatial domain random noise attenuation, three-dimensional in-trace interpolation, one-step three-dimensional time migration, band-pass filtering, amplitude equalization, and outputting a standard SEGY format migrated data volume; completion of three-dimensional seismic exploration; the quality of the original data acquisition and processing of the present invention is relatively high, an advanced processing system is selected, a data volume with high signal-to-noise ratio, high resolution, and high fidelity is obtained, and all known geological and geophysical data in the area are comprehensively used to conduct a detailed comparison, analysis, and interpretation of the seismic data, obtaining relatively high-quality geological results, providing detailed geological basic data for the later mine production.

[0036] Furthermore, the receiving line spacing is 40 m, the longitudinal coverage is 7 times, the transverse coverage is 5 times, for a total of 35 times. The coverage times are for reference Figure 2 , and the rose diagram is for reference Figure 3 . For specific detailed parameters, refer to Table 1.

[0037] Table 1

[0038] Name Parameter Observation system type 10 lines and 10 shots, in a beam shape, shooting in the middle Number of receiving channels 840 (10 lines × 84 channels) Number of receiving lines 10 lines Receiving line interval 40m Receiving channel interval 20m Shot row interval for excitation 120m Shot point interval for excitation 20m CDP grid 10 m (horizontal) × 10 m (vertical) Number of stacking times 35 times (5 horizontal × 7 vertical) Maximum vertical offset 830m Maximum non-longitudinal offset 882.32m Minimum non-longitudinal offset 22.28m

[0039] Furthermore, the geophones are 7 Hz geophones, the seismograph is a 428XL high-resolution digital seismograph, the sampling interval is 0.5 ms, the recording length is 2 s, the recording format is SEG-D, and the preamplification gain is 12 db.

[0040] Furthermore, the spatial attributes are defined as accurately establishing the shot points and geophone points and drawing accurate position maps of the shot points and geophone points.

[0041] Furthermore, the trace editing is to eliminate abnormal working traces and suppress noise.

[0042] Furthermore, static correction is one of the key links in seismic data processing. Due to the lateral variations in surface elevation, thickness, and velocity of the surface low (velocity) layer, the travel time differences of seismic waves generated therefrom will have a certain adverse effect on the signal stacking effect, resulting in a decrease in the signal-to-noise ratio and frequency of the reflected wave in-phase axis. Applying appropriate static correction modules and parameters can eliminate this time difference and ensure the quality of the stacked section. For the changes in geophone point elevation and shot hole depth, we selected an average elevation of 920 m as the static correction reference plane and a replacement velocity of 4000 m / s.

[0043] Furthermore, to address the issue of amplitude variations caused by changes in surface excitation and reception conditions during processing, a method of cascading spherical spreading compensation and surface-consistent amplitude compensation is used. Spherical spreading compensation solves the attenuation problem of amplitude energy due to the spherical spreading of seismic waves during downward propagation along the propagation distance. Surface-consistent amplitude compensation mainly compensates for the spatial directional amplitude energy differences caused by changes in excitation and reception conditions during the propagation of seismic waves. To effectively grasp the amplitude energy variations of the original data and the amplitude compensation effect, we compare the results after amplitude compensation with the amplitude of the original data through single-shot analysis to judge the compensation effect; Figure 4 is the single-shot comparison before and after amplitude recovery.

[0044] Furthermore, for the main interfering waves existing in the original data, targeted denoising is performed before deconvolution to improve the accuracy of the deconvolution factor. Through experiments, in this processing, the main interfering wave suppression methods selected include: using the frequency-divided abnormal amplitude suppression method for outliers and abnormal amplitudes; testing the adaptive surface wave attenuation technology and regional filtering technology for surface waves, and the adaptive surface wave attenuation has a better effect through comparison; using the random noise attenuation technology for random noise. Figure 5 It is the comparison of a single shot before and after denoising.

[0045] Furthermore, different excitation and reception conditions result in certain changes in the wavelet amplitude, frequency, phase, etc. of the original data. Surface consistent processing is the best means to eliminate these differences. In the processing, it mainly starts from the following two aspects: applying the surface consistent deconvolution technology to correct the seismic wavelet and eliminate the influence of surface inconsistent factors on the seismic wavelet, so as to enhance the lateral stability of the seismic wavelet. Then, based on the residual static correction, predictive deconvolution is carried out to further compress the wavelet and improve the vertical resolution. For the actual data and geological tasks in this area, we select the surface consistent predictive deconvolution, and its test parameters are: prediction step lengths of 8, 12, 14, and 16 ms, and factor length of 100 ms. Finally, the best effect is achieved with 14 ms. It can be seen from Figure 6 、 7 that the high-frequency components are strengthened and the frequency band is also broadened.

[0046] Velocity analysis: Velocity is one of the important parameters in seismic data processing, and its accuracy directly affects the effect of stacking processing. To improve the accuracy of velocity spectrum interpretation, first, velocity scanning is carried out to obtain the velocity law from shallow to deep in this area, and then the velocity spectrum is calculated based on this reference velocity. The density of the velocity spectrum is 100 m × 100 m, and it is iterated three times with the residual static correction.

[0047] Automatic residual static correction can eliminate the high-frequency residual static correction amount existing in the record, which is one of the important means to ensure the best stacking effect of the effective wave. On this basis, stacking velocity analysis is carried out to provide more accurate stacking velocity information for the subsequent stacking processing. It should be noted that residual static correction and velocity analysis are a process of repeated iteration, and the number of iterations affects the processing accuracy to a certain extent. In the process of this data processing, this process is carried out twice. After automatic residual static correction, the continuity of the in-phase axis of the effective wave is significantly improved, and the profile quality is significantly improved. See Figure 8 。

[0048] 3D migration is a key step in the spatial imaging of 3D data volumes. Since DMO stacking can achieve prestack partial migration, enabling better focusing of reflected waves for imaging; on this basis, poststack 3D one-step migration can make the reflected waves fully focused for imaging, achieving the purpose of truly reflecting the actual situation of subsurface structures. This not only realizes true 3D migration but also helps to preserve various dynamic characteristics of the reflected waves.

[0049] The change in horizontal displacement after migration is controlled by the migration velocity and is proportional to the square of the migration velocity. That is, the smaller the migration velocity, the less the offset of the dipping event towards the updip direction. Conversely, an excessive migration velocity will cause the side effect of overmigration. In this area, one-step migration is adopted, and the migration velocity is calibrated from the DMO velocity by boreholes. Through repeated comparisons, migration is carried out using 95% of the stacking velocity, with a continuation step of 10 ms, and the migration effect is the best. See Figure 9 Profiles before and after migration.

[0050] DMO, namely dip moveout correction, is to first migrate the data after normal moveout correction to zero offset and then stack it, so that various dip cross reflections can achieve the best imaging effect.

[0051] In the present invention, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, there will be changes in the specific implementation manner and application scope according to the idea of the present invention. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. A three-dimensional seismic exploration method, characterized in that, Including the following steps: Geometric network layout; adopting a 10-line and 10-shot beam observation system, with the receiving lines arranged perpendicular to the stratigraphic strike; Shot firing; Data acquisition and processing: using geophones and a seismograph for data collection; decoding the original data collected by the geophones and the seismograph, defining spatial attributes, trace editing, first arrival picking, tomographic static correction, true amplitude recovery, band-pass filtering, surface-consistent predictive deconvolution, common midpoint gather, velocity analysis, three-dimensional residual static correction, DMO correction, frequency and spatial domain random noise attenuation, three-dimensional in-trace interpolation, one-step three-dimensional time migration, band-pass filtering, amplitude equalization, and outputting a migrated data volume in the standard SEGY format; Completion of three-dimensional seismic exploration.

2. The three-dimensional seismic exploration method according to claim 1, wherein The receiver line interval is 40 m, the longitudinal coverage fold is 7 times, and the lateral coverage fold is 5 times.

3. The three-dimensional seismic exploration method according to claim 1, characterized in that, The geophones are 7 Hz geophones, the seismograph is a 428XL high-resolution digital seismograph, the sampling interval is 0.5 ms, the recording length is 2 s, the recording format is SEG-D, and the pre-amplification gain is 12 db.

4. The three-dimensional seismic prospecting method according to claim 1, characterized in that, The spatial attribute definition is to accurately establish shot points and receiver points and draw an accurate location map of the shot points and receiver points.

5. The three-dimensional seismic prospecting method according to claim 1, wherein The trace editing is to eliminate abnormally operating traces and suppress noise.

6. The three-dimensional seismic prospecting method according to claim 1, wherein The frequency and spatial domain random noise attenuation method is selected as follows: for outliers and abnormal amplitudes, a frequency-divided abnormal amplitude suppression method is adopted; for surface waves, an adaptive surface wave attenuation technique and a regional filtering technique are adopted.

7. The three-dimensional seismic exploration method according to claim 1, characterized in that, Applying the surface-consistent predictive deconvolution technique to correct the seismic wavelet, eliminating the influence of surface-inconsistent factors on the seismic wavelet, and then, on the basis of the residual static correction, performing predictive deconvolution to further compress the wavelet and improve the vertical resolution.

8. The three-dimensional seismic exploration method according to claim 1, wherein The DMO correction, i.e., dip moveout correction, is to first migrate the data after normal moveout to zero offset and then stack it.

9. The three-dimensional seismic prospecting method according to claim 8, characterized in that, The migration velocity of the one-step migration is obtained by calibrating the DMO velocity with boreholes.

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