CN112415592B - Seismic data five-dimensional spectrum analysis noise suppression method, storage medium and computing equipment - Google Patents
Seismic data five-dimensional spectrum analysis noise suppression method, storage medium and computing equipment Download PDFInfo
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- CN112415592B CN112415592B CN201910780174.7A CN201910780174A CN112415592B CN 112415592 B CN112415592 B CN 112415592B CN 201910780174 A CN201910780174 A CN 201910780174A CN 112415592 B CN112415592 B CN 112415592B
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- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. analysis, for interpretation, for correction
- G01V1/36—Effecting static or dynamic corrections on records, e.g. correcting spread; Correlating seismic signals; Eliminating effects of unwanted energy
Abstract
The invention relates to a seismic data five-dimensional spectrum analysis noise suppression method, a storage medium and computing equipment, wherein the method comprises the following steps: converting the three-dimensional common shot point gather into a pre-stack three-dimensional CDP gather by using the common depth point grid; forming a rose diagram according to the position distribution density of the shot-picking coordinate central point in the prestack three-dimensional CDP channel set; dividing the rose diagram into a plurality of offset vector pieces, and combining all the offset vector pieces into a five-dimensional OVT body; and carrying out five-dimensional spectrum analysis and superposition denoising on the five-dimensional OVT body to suppress the noise of the seismic data.
Description
Technical Field
The invention relates to the technical field of seismic exploration data processing, in particular to a seismic data five-dimensional spectrum analysis noise suppression method, a storage medium and computing equipment.
Background
Suppressing noise is an important link in seismic exploration data processing. Along with the continuous deepening of seismic exploration, the acquired seismic data are often complex areas with low signal-to-noise ratio, such as deserts, mountain areas, loess tablelands and the like; in addition, the complex terrain, the great difference of the near-surface physical properties, the complex change of geological structure and lithology and the larger oil and gas burial depth sometimes cause great difficulty in the acquisition and processing of exploration seismic data. In addition, with the change of geological exploration purposes, the oil and gas exploration from the original structure is changed to lithological oil and gas exploration, and the requirements on the seismic data processing quality and the signal-to-noise ratio of geological data are higher and higher.
Throughout the exploration industry, most denoising methods are two-dimensional or three-dimensional. The resolution of signal and noise is very different for different dimensional viewing angles. For part of strong energy noise, random phenomenon is not necessarily shown on a conventional gather, but the traditional two-dimensional or three-dimensional denoising method can not do the same.
Disclosure of Invention
Aiming at the blank of the current five-dimensional noise suppression, the invention provides a seismic data five-dimensional spectrum analysis noise suppression method, a storage medium and a computing device.
According to one aspect of the invention, a seismic data five-dimensional spectrum analysis noise suppression method is provided, which comprises the following steps:
converting the three-dimensional shot-sharing gather into a pre-stack three-dimensional CDP gather by using a common depth point grid;
forming a rose diagram according to the position distribution density of the shot-picking coordinate central point in the prestack three-dimensional CDP channel set;
dividing the rose diagram into a plurality of offset vector pieces, and combining all the offset vector pieces into a five-dimensional OVT body; and
and carrying out five-dimensional spectrum analysis and superposition denoising on the five-dimensional OVT body to suppress the noise of the seismic data.
Preferably, converting the three-dimensional common shot gathers to prestack three-dimensional CDP gathers using a common depth point grid, comprising:
and sequentially placing each seismic channel in the three-dimensional common shot point channel set in a common depth point grid according to the position of the shot detection coordinate central point to form the pre-stack three-dimensional CDP channel set.
Preferably, the step of dividing the rose diagram into a plurality of offset vector pieces and combining all the offset vector pieces into a five-dimensional OVT body includes:
dividing the rose diagram into a plurality of sector surface elements by utilizing equally spaced concentric circles and bisectors passing through the circle center, wherein one sector surface element is one offset vector piece; and
and sequentially arranging all the offset vector pieces to form the five-dimensional OVT body.
Preferably, the denoising and stacking of the five-dimensional OVT body is performed to suppress the noise of the seismic data, and the denoising includes:
for each compressed noise channel in the five-dimensional OVT body, forming a five-dimensional OVT gather which takes the compressed noise channel as the center and contains all the compressed noise channels,
wherein the five-dimensional OVT gather comprises: offset bin number, azimuth bin number, CDP number, and line number.
Preferably, the noise of the seismic data is suppressed by performing five-dimensional spectral analysis and superposition denoising on the five-dimensional OVT body, and the method further includes:
in the five-dimensional OVT channel set, different apparent dip angle combinations of the current pressed noise channel along the offset distance, the azimuth angle, the line and the CDP four directions are determined, and the spectrum values of the current pressed noise channel on sampling points under different apparent dip angle combinations are respectively calculated;
selecting the largest of said spectral values as the largest correlation spectral value; and
and determining the view dip angle combination corresponding to the maximum correlation spectrum value.
Preferably, different combinations of said apparent dip angles are determined according to the maximum scan range and scan interval of the currently compressed noise track in the four directions of offset, azimuth, along line and CDP.
Preferably, the spectral values are calculated according to the following expression:
where f a, o, y, x, t represents the amplitude value of the current compressed channel at a certain sampling point along azimuth angle a, offset distance o, line direction y, CDP direction x and time t under a certain dip angle combination, the left-hand numerator of the equation represents the square of the amplitude sum, and the right-hand denominator of the equation represents the product of the coverage order M and the square sum of the amplitude.
Preferably, the noise of the seismic data is suppressed by performing five-dimensional spectral analysis and superposition denoising on the five-dimensional OVT body, and the method further comprises:
in the five-dimensional OVT gather, taking each pressed noise channel as the current pressed noise channel in turn, calculating four optimal dip angles of each pressed noise channel, and carrying out superposition denoising along the four optimal dip angles to suppress the noise of the seismic data,
and the four optimal apparent dip angles are the apparent dip angle combination corresponding to the maximum correlation spectrum value.
According to another aspect of the invention, there is provided a storage medium having stored thereon executable code which, when executed by a processor, causes the processor to perform the seismic data five-dimensional spectral analysis noise suppression method described above.
According to yet another aspect of the present invention, there is provided a computing device comprising:
a processor; and
a memory having executable code stored thereon, which when executed by the processor, causes the processor to perform the seismic data five-dimensional spectral analysis noise suppression method described above.
Compared with the prior art, one or more embodiments in the above scheme can have the following advantages or beneficial effects:
by applying the seismic data five-dimensional spectrum analysis noise suppression method provided by the embodiment of the invention, the noise suppression capability is fully exerted by realizing the method in a five-dimensional OVT domain. For part of strong energy noise, the phenomenon of randomness is not necessarily shown on a conventional gather, and the traditional superposition denoising can not be realized. In the five-dimensional OVT trace set, the noise is more random, and the method can effectively suppress the noise of the type.
In addition, for data with a particularly low signal-to-noise ratio, the five-dimensional spectrum analysis noise suppression device can play a good role, has the amplitude maintaining function, is high in fidelity and does not generate the technical effect of construction artifacts.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
FIG. 1 is a flow chart of a seismic data five-dimensional spectral analysis noise suppression method according to an embodiment of the invention.
Fig. 2 schematically shows a common depth point CDP grid according to an embodiment of the invention.
FIG. 3 schematically illustrates a three-dimensional common shot gather according to an embodiment of the invention.
FIG. 4 schematically shows a rose diagram according to an embodiment of the invention.
Fig. 5a shows original pre-stack seismic data, fig. 5b shows pre-stack seismic data after three-dimensional random noise attenuation processing, and fig. 5c shows pre-stack seismic data before non-stack denoising is processed by a seismic data five-dimensional spectrum analysis noise suppression method according to an embodiment of the invention.
Fig. 6a shows an effect diagram of the original pre-stack seismic data after superposition and denoising, fig. 6b shows an effect diagram of the pre-stack seismic data after superposition and denoising through three-dimensional random noise attenuation processing, and fig. 6c shows the pre-stack seismic data after processing through the seismic data five-dimensional spectrum analysis noise suppression method according to the embodiment of the invention.
Detailed Description
The following detailed description of the embodiments of the present invention will be provided with reference to the drawings and examples, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented. It should be noted that, as long as there is no conflict, the embodiments and the features of the embodiments of the present invention may be combined with each other, and the technical solutions formed are within the scope of the present invention.
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details or with a specific embodiment that is described.
In order to solve the technical problems that in the prior art, a two-dimensional or three-dimensional denoising method is poor in denoising effect on high-density and wide-azimuth seismic data, especially on noise with extremely strong amplitude and not completely random, and the noise cannot be removed by a traditional two-dimensional or three-dimensional denoising method, the embodiment of the invention provides a seismic data five-dimensional spectrum analysis noise suppression method, a storage medium and a computing device.
Example one
FIG. 1 is a flow chart of a seismic data five-dimensional spectral analysis noise suppression method according to an embodiment of the invention. As shown in fig. 1, the method includes:
step S1: converting the three-dimensional shot-sharing gather into a pre-stack three-dimensional CDP gather by using a common depth point grid;
step S2: forming a rose diagram according to the position distribution density of the shot-picking coordinate central point in the prestack three-dimensional CDP channel set;
step S3: dividing the rose diagram into a plurality of offset vector pieces, and combining all the offset vector pieces into a five-dimensional OVT body; and
step S4: and carrying out five-dimensional spectrum analysis and superposition denoising on the five-dimensional OVT body to suppress the noise of the seismic data.
Fig. 2 schematically shows a common depth point CDP grid according to an embodiment of the invention. FIG. 3 schematically illustrates a three-dimensional common shot gather according to an embodiment of the invention. Among them, CDP (common depth point). As shown in fig. 2 and 3, in step S1, the three-dimensional common shot gathers are converted into prestack three-dimensional CDP gathers using the common depth point grid. Specifically, for a three-dimensional common shot gather, each seismic trace in the three-dimensional common shot gather is placed in a common depth point grid (CDP grid) according to the position of a shot detection coordinate center point, so that the seismic traces are arranged into a pre-stack three-dimensional CDP gather. In fig. 3, the thick lines are gun lines and the thin lines are detector lines.
After a large number of practical demonstrations, the following findings are found: in pre-stack three-dimensional CDP trace concentration, the near offset and far offset traces have not necessarily good correlation although the reflection points are very close, and the two traces with close offset and azimuth have better correlation. In view of this, the embodiments of the present invention rearrange the tracks with similar Offset and azimuth angles to form the five-dimensional OVT (OVT: Offset Vector Tile) of the embodiments of the present invention.
FIG. 4 schematically shows a rose diagram according to an embodiment of the invention. As shown in fig. 4, in step S2, a rose diagram is formed based on the position distribution density of shot coordinate center points in the prestack three-dimensional CDP gather. The rose diagram is referred to as the joint rose diagram. Specifically, in the prestack three-dimensional CDP gather, a plurality of shot detection coordinate central points are arranged, and a rose diagram is formed by taking one shot detection coordinate central point as a center and according to the position distribution density of the shot detection coordinate central points.
In step S3, the rose diagram is split into a plurality of offset vector pieces, and all the offset vector pieces are combined into a five-dimensional OVT volume. Specifically, as shown in fig. 4, the interval of the concentric circles is determined according to the magnitude of the offset distance, and the interval of the bisector is determined according to the magnitude of the azimuth angle. And (3) dividing the rose diagram into a plurality of sector surface elements by utilizing equally spaced concentric circles and bisectors passing through the circle center, wherein one sector surface element is an offset vector sheet OVT.
As can be seen from the above, the offset vector field OVT is defined by azimuth and offset, i.e., a plurality of offset vector fields OVT are selected from the prestack three-dimensional CDP gather according to azimuth and offset. Where an OVT corresponds to a small three-dimensional volume (line, CDP and time). Therefore, in the same offset vector piece OVT obtained in step S3, the correlation between any two pieces of data with the CDP is far better than that between other combinations.
Next, all OVTs are sequentially arranged and combined to form a five-dimensional OVT body. Through the above process, the prestack three-dimensional CDP gather can be converted into a five-dimensional OVT body. There is better correlation between adjacent tracks of the five-dimensional OVT body than the original prestack three-dimensional CDP gather.
In step S4, first, after the five-dimensional OVT volume is determined, a five-dimensional OVT gather is formed that includes all the suppressed channels and is centered on any one of the suppressed channels. Each channel before denoising is called a channel to be suppressed, that is, the channel to be suppressed refers to data before denoising. In the embodiment of the invention, the five-dimensional OVT gather is formed by filling a five-dimensional grid instead of the conventional trace sorting.
Specifically, an empty five-dimensional grid is formed, and then each trace in the plurality of offset vector slices is placed in the five-dimensional grid in turn to form a five-dimensional OVT gather. For example, assume that there are N channels being compressed and the offset bin number of the current channel being compressed is koThe azimuth surface element number is kaCDP number kxLine number ky. With this track as the center, the five-dimensional OVT gather consists of:
wherein N isxCDP number, N, representing the nth compressed-noise channel in a five-dimensional OVT gatheryLine number, N, representing the nth compressed noise channel in a five-dimensional OVT gatheroOffset bin number, N, representing the nth compressed noise channel in a five-dimensional OVT channel gatheraAnd indicating the azimuth bin number of the nth compressed noise channel in the five-dimensional OVT channel set.
Next, the dip angle combinations of the current pressed noise channel along the offset, along the azimuth, along the line and along the CDP are determined, and the spectrum values of the current pressed noise channel at the sampling points under different dip angle combinations are respectively calculated. Wherein a sample point refers to a grid point of a five-dimensional grid.
Specifically, the apparent dip angle combination is determined by: and determining different apparent dip angle combinations according to the maximum scanning ranges and scanning intervals of the current compressed noise channel along the offset distance, the azimuth angle, the line and the CDP. The maximum scanning range and the scanning interval may be flexibly set according to actual situations, and the present invention is not limited thereto.
The calculation of the spectral values is, for example, according to the following expression:
f a, o, y, x, t represents the amplitude value of the current compressed noise channel at a certain sampling point along the azimuth angle a, the offset distance o, the line direction y, the CDP direction x and the time t under a certain dip angle combination; the numerator on the right side of the equation represents the square of the sum of the amplitudes and the denominator on the right side of the equation represents the product of the number of coverage M times and the sum of the squares of the amplitudes.
And calculating the spectral value of the current noise channel to be suppressed on the sampling point under different combinations of the apparent dip angles through the calculation. Then, the largest of these spectral values is selected as the largest correlation spectral value. And simultaneously, determining the view dip angle combination corresponding to the maximum correlation spectrum value.
And then, taking each noise-suppressed channel of the five-dimensional OVT body as a current noise-suppressed channel in turn, and forming a five-dimensional OVT channel set taking the channel as the center. And based on the spectrum value calculation formula, sequentially calculating the maximum correlation spectrum value of each noise channel to be pressed on the sampling point, and determining the view dip angle combination corresponding to the maximum correlation spectrum value of each noise channel to be pressed, namely determining four optimal view dip angles of each noise channel to be pressed. Wherein the four optimal apparent dip angles include: an optimal apparent dip angle in the offset direction, an optimal apparent dip angle in the azimuthal direction, an optimal apparent dip angle in the linear direction, and an optimal apparent dip angle in the CDP direction.
And finally, each pressed noise channel is subjected to superposition denoising along the view dip angle combination direction corresponding to the maximum correlation spectrum value of the pressed noise channel so as to suppress the noise of the seismic data.
In summary, by applying the seismic data five-dimensional spectrum analysis noise suppression method provided by the embodiment of the invention, the noise suppression capability is fully exerted by realizing the method in the five-dimensional OVT domain. For part of strong energy noise, the phenomenon of randomness is not necessarily shown on a conventional gather, and the traditional superposition denoising can not be realized. In the five-dimensional OVT channel set, the partial noise is more random, and the method can effectively suppress the noise of the type.
In addition, for data with a particularly low signal-to-noise ratio, the five-dimensional spectrum analysis noise suppression device can play a good role, has the amplitude maintaining function, is high in fidelity and does not generate the technical effect of construction artifacts.
Example two
The second embodiment is an implementation manner of the first embodiment, and provides a method for suppressing noise in five-dimensional spectrum analysis of seismic data. FIG. 1 is a flow chart of a seismic data five-dimensional spectral analysis noise suppression method according to an embodiment of the invention. As shown in fig. 1, the method includes:
step S1: converting the three-dimensional shot-sharing gather into a pre-stack three-dimensional CDP gather by using a common depth point grid;
step S2: forming a rose diagram according to the position distribution density of the shot-picking coordinate central point in the prestack three-dimensional CDP channel set;
step S3: dividing the rose diagram into a plurality of offset vector pieces, and combining all the offset vector pieces into a five-dimensional OVT body; and
step S4: and carrying out five-dimensional spectral analysis and superposition denoising on the five-dimensional OVT body to suppress the noise of the seismic data.
Fig. 2 schematically illustrates a common depth point CDP mesh according to an embodiment of the present invention. FIG. 3 schematically illustrates a three-dimensional common shot gather according to an embodiment of the invention. As shown in fig. 2 and 3, in step S1, the three-dimensional common shot gathers are converted into prestack three-dimensional CDP gathers using the common depth point grid. Specifically, for a three-dimensional common shot gather, each seismic trace in the three-dimensional common shot gather is placed in a common depth point grid (CDP grid) according to the position of a shot detection coordinate center point, so that the seismic traces are arranged into a pre-stack three-dimensional CDP gather. In fig. 3, the thick lines are gun lines and the thin lines are detector lines.
After a large number of practical demonstrations, the following findings are found: in pre-stack three-dimensional CDP trace concentration, the near offset and far offset traces have not necessarily good correlation although the reflection points are very close, and the two traces with close offset and azimuth have better correlation. In view of this, the embodiments of the present invention rearrange the tracks with similar Offset and azimuth angles to form the five-dimensional OVT (OVT: Offset Vector Tile) of the embodiments of the present invention.
FIG. 4 schematically shows a rose diagram according to an embodiment of the invention. As shown in fig. 4, in step S2, a rose diagram is formed based on the position distribution density of shot coordinate center points in the prestack three-dimensional CDP gather. Specifically, in the prestack three-dimensional CDP gather, a plurality of shot detection coordinate central points are arranged, and a rose diagram is formed by taking one shot detection coordinate central point as a center and according to the position distribution density of the shot detection coordinate central points.
In step S3, the rose diagram is split into a plurality of offset vector pieces, and all the offset vector pieces are combined into a five-dimensional OVT volume. Specifically, as shown in fig. 4, the interval of the concentric circles is determined according to the magnitude of the offset distance, and the interval of the bisector is determined according to the magnitude of the azimuth angle. And (3) dividing the rose diagram into a plurality of sector surface elements by utilizing equally spaced concentric circles and bisectors passing through the circle center, wherein one sector surface element is an offset vector sheet OVT.
From the above, the offset vector pieces OVT are defined by azimuth and offset, i.e., a plurality of offset vector pieces OVT are selected from the prestack three-dimensional CDP gather according to azimuth and offset. Where one OVT corresponds to one small three-dimensional volume (line, CDP and time). Therefore, in the same offset vector piece OVT obtained in step S3, the correlation between any two pieces of data with the CDP is far better than that between other combinations.
Next, all OVTs are sequentially arranged and combined to form a five-dimensional OVT body. Through the above process, the prestack three-dimensional CDP gather can be converted into a five-dimensional OVT body. There is better correlation between adjacent tracks of the five-dimensional OVT body than the original prestack three-dimensional CDP gather.
In step S4, first, after the five-dimensional OVT volume is determined, a five-dimensional OVT gather is formed that includes all the suppressed channels and is centered on any one of the suppressed channels. Each channel before denoising is called a channel to be suppressed, that is, the channel to be suppressed refers to data before denoising. In the embodiment of the invention, the five-dimensional OVT gather is formed by filling a five-dimensional grid instead of the conventional trace sorting.
Specifically, an empty five-dimensional grid is formed, and then each trace in the plurality of offset vector slices is placed in the five-dimensional grid in turn to form a five-dimensional OVT gather. For example, assume that there are N channels to be suppressed and the number of offset bins of the current channel to be suppressed is koThe azimuth surface element number is kaCDP number kxLine number ky. With this track as the center, the five-dimensional OVT gather consists of:
wherein N isxCDP number, N, representing the nth compressed-noise channel in a five-dimensional OVT gatheryLine number, N, representing the nth compressed noise channel in a five-dimensional OVT gatheroOffset bin number, N, representing the nth compressed noise channel in a five-dimensional OVT channel gatheraAnd indicating the azimuth bin number of the nth compressed noise channel in the five-dimensional OVT channel set.
Next, the dip angle combinations of the current pressed noise channel along the offset, along the azimuth, along the line and along the CDP are determined, and the spectrum values of the current pressed noise channel at the sampling points under different dip angle combinations are respectively calculated. Wherein a sample point refers to a grid point of a five-dimensional grid.
Specifically, the apparent dip angle combination is determined by: and determining different apparent dip angle combinations according to the maximum scanning ranges and scanning intervals of the current compressed noise channel along the offset distance, the azimuth angle, the line and the CDP.
Preferably, in the second embodiment of the present invention, as an implementation manner of the first embodiment: the maximum scanning ranges of the current noise-suppressed channels along the offset distance, the azimuth angle, the line and the CDP direction are the same, and the scanning intervals are also the same. For example, the maximum scan range is 100 °, and the scan interval is 5 °. Thus, the number of scans in the offset, azimuth, along line, and CDP directions of the current compressed channel can be determined, 20, and 20, respectively. The number of combinations of apparent tilt angles, i.e. 20 x 160000, is determined by multiplying the number of scans in four directions. Correspondingly, a combination of apparent tilt angles may also be determined, which includes, for example, (5 ° ) and (20 °, 30 °, 40 °, 50 °).
The spectral value is calculated, for example, according to the following expression:
f a, o, y, x, t represents the amplitude value of the current compressed noise channel at a certain sampling point along the azimuth angle a, the offset distance o, the line direction y, the CDP direction x and the time t under a certain dip angle combination; the numerator on the right side of the equation represents the square of the sum of the amplitudes and the denominator on the right side of the equation represents the product of the number of coverage M times and the sum of the squares of the amplitudes.
And calculating the spectral value of the current noise channel to be suppressed on the sampling point under different combinations of the apparent dip angles through the calculation. Then, the largest of these spectral values is selected as the largest correlation spectral value. And simultaneously, determining the view dip angle combination corresponding to the maximum correlation spectrum value.
And then, sequentially taking each suppressed channel of the five-dimensional OVT body as a current suppressed channel to form a five-dimensional OVT channel set taking the channel as the center. And sequentially calculating the maximum correlation spectrum value of each pressed noise channel on the sampling point based on the spectrum value calculation formula, and determining the view dip angle combination corresponding to the maximum correlation spectrum value of each pressed noise channel, namely determining four optimal view dip angles of each pressed noise channel. Wherein the four optimal apparent dip angles include: an optimal apparent dip angle in the offset direction, an optimal apparent dip angle in the azimuthal direction, an optimal apparent dip angle in the linear direction, and an optimal apparent dip angle in the CDP direction.
And finally, each pressed noise channel is subjected to superposition denoising along the view dip angle combination direction corresponding to the maximum correlation spectrum value of the pressed noise channel so as to suppress the noise of the seismic data.
In order to verify the practical effect of the seismic data five-dimensional spectrum analysis noise suppression method, certain seismic data are selected for processing and analysis.
Fig. 5a shows original pre-stack seismic data, fig. 5b shows pre-stack seismic data after three-dimensional random noise attenuation processing, and fig. 5c shows pre-stack seismic data before non-stack denoising is processed by a seismic data five-dimensional spectrum analysis noise suppression method according to an embodiment of the invention.
As shown in fig. 5 a-5 c, the original pre-stacked CDP gather has relatively strong surface wave interference and some of the effective signal is masked. After three-dimensional random noise attenuation and pressure noise reduction, surface waves are suppressed to a certain degree, but surface wave interference still exists. After noise suppression through five-dimensional spectral analysis, the surface waves basically disappear. Compared with three-dimensional random noise attenuation, the seismic data five-dimensional spectrum analysis noise suppression method provided by the embodiment of the invention has the advantage that the noise suppression effect of the seismic data is obviously improved.
Fig. 6a shows an effect diagram of the original pre-stack seismic data after superposition and denoising, fig. 5b shows an effect diagram of the pre-stack seismic data after superposition and denoising through three-dimensional random noise attenuation processing, and fig. 5c shows the pre-stack seismic data after processing through the seismic data five-dimensional spectrum analysis noise suppression method according to the embodiment of the invention.
As shown in fig. 6a to 6c, through five-dimensional spectrum analysis noise suppression, the random noise energy is suppressed well, and the in-phase axis is clearer and more continuous. Compared with the three-dimensional random noise denoising result shown in fig. 6b, the five-dimensional denoising imaging precision is higher, and the resolutions of the medium-shallow layer and the target layer are improved.
In summary, by applying the seismic data five-dimensional spectrum analysis noise suppression method provided by the embodiment of the invention, the noise suppression capability is fully exerted by realizing the method in the five-dimensional OVT domain. For part of strong energy noise, the phenomenon of randomness is not necessarily shown on a conventional gather, and the traditional superposition denoising can not be realized. In the five-dimensional OVT trace set, the noise is more random, and the method can effectively suppress the noise of the type.
In addition, for data with a particularly low signal-to-noise ratio, the five-dimensional spectrum analysis noise suppression device can play a good role, has the amplitude maintaining function, is high in fidelity and does not generate the technical effect of construction artifacts.
EXAMPLE III
The third embodiment is another implementation manner of the first embodiment, and provides a method for suppressing noise in five-dimensional spectrum analysis of seismic data. FIG. 1 is a flow chart of a seismic data five-dimensional spectral analysis noise suppression method according to an embodiment of the invention. As shown in fig. 1, the method includes:
step S1: converting the three-dimensional shot-sharing gather into a pre-stack three-dimensional CDP gather by using a common depth point grid;
step S2: forming a rose diagram according to the position distribution density of the shot-examination coordinate central points in the prestack three-dimensional CDP channel set;
step S3: dividing the rose diagram into a plurality of offset vector pieces, and combining all the offset vector pieces into a five-dimensional OVT body; and
step S4: and carrying out five-dimensional spectrum analysis and superposition denoising on the five-dimensional OVT body to suppress the noise of the seismic data.
Fig. 2 schematically shows a common depth point CDP grid according to an embodiment of the invention. FIG. 3 schematically illustrates a three-dimensional common shot gather according to an embodiment of the invention. As shown in fig. 2 and 3, in step S1, the three-dimensional common shot gathers are converted into prestack three-dimensional CDP gathers using the common depth point grid. Specifically, for a three-dimensional common shot gather, each seismic trace in the three-dimensional common shot gather is placed in a common depth point grid (CDP grid) according to the position of a shot detection coordinate center point, so that the seismic traces are arranged into a pre-stack three-dimensional CDP gather. In fig. 3, the thick lines are gun lines and the thin lines are detector lines.
After a large number of practical demonstrations, the following findings are found: in pre-stack three-dimensional CDP trace concentration, the near offset and far offset traces have not necessarily good correlation although the reflection points are very close, and the two traces with close offset and azimuth have better correlation. In view of this, the embodiments of the present invention rearrange the tracks with similar Offset and azimuth angles to form the five-dimensional OVT (OVT: Offset Vector Tile) of the embodiments of the present invention.
FIG. 4 schematically shows a rose diagram according to an embodiment of the invention. As shown in FIG. 4, in step S2, a rose diagram is formed based on the density of the location distribution of shot coordinate center points in the prestack three-dimensional CDP gather. Specifically, in the prestack three-dimensional CDP gather, a plurality of shot detection coordinate central points are arranged, one shot detection coordinate central point is taken as a center, and the rose diagram is formed according to the position distribution density of the shot detection coordinate central points.
In step S3, the rose diagram is split into a plurality of offset vector pieces, and all the offset vector pieces are combined into a five-dimensional OVT volume. Specifically, as shown in fig. 4, the interval of the concentric circles is determined according to the magnitude of the offset distance, and the interval of the bisector is determined according to the magnitude of the azimuth angle. And (3) dividing the rose diagram into a plurality of sector surface elements by utilizing equally spaced concentric circles and bisectors passing through the circle center, wherein one sector surface element is an offset vector sheet OVT.
As can be seen from the above, the offset vector field OVT is defined by azimuth and offset, i.e., a plurality of offset vector fields OVT are selected from the prestack three-dimensional CDP gather according to azimuth and offset. Where one OVT corresponds to one small three-dimensional volume (line, CDP and time). Therefore, in the same offset vector piece OVT obtained in step S3, the correlation between any two pieces of data with the CDP is far better than that of other combinations.
Next, all OVTs are sequentially arranged and combined to form a five-dimensional OVT body. Through the above process, the prestack three-dimensional CDP gather can be converted into a five-dimensional OVT body. There is better correlation between adjacent tracks of the five-dimensional OVT body than the original prestack three-dimensional CDP gather.
In step S4, first, after the five-dimensional OVT volume is determined, a five-dimensional OVT gather is formed that includes all the channels to be compressed, with any one channel to be compressed being the center. Each channel before denoising is called a channel to be suppressed, that is, the channel to be suppressed refers to data before denoising. In the embodiment of the invention, the five-dimensional OVT gather is formed by filling a five-dimensional grid instead of the conventional trace sorting.
Specifically, an empty five-dimensional grid is formed, and then each trace in the plurality of offset vector slices is placed in the five-dimensional grid in turn to form a five-dimensional OVT gather. For example, assume that there are N channels to be suppressed and the number of offset bins of the current channel to be suppressed is koThe azimuth surface element number is kaCDP number kxLine number ky. With this track as the center, the five-dimensional OVT gather consists of:
wherein, NxCDP number, N, representing the nth compressed channel in a five-dimensional OVT gatheryLine number, N, representing the nth channel of noise being suppressed in five-dimensional OVT channel setoOffset bin number, N, representing the nth compressed noise channel in a five-dimensional OVT channel gatheraAnd indicating the azimuth bin number of the nth compressed noise channel in the five-dimensional OVT channel set.
Next, the dip angle combinations of the current pressed noise channel along the offset, along the azimuth, along the line and along the CDP are determined, and the spectrum values of the current pressed noise channel at the sampling points under different dip angle combinations are respectively calculated. Wherein a sample point refers to a grid point of a five-dimensional grid.
Specifically, the apparent dip angle combination is determined by: and determining different apparent dip angle combinations according to the maximum scanning ranges and scanning intervals of the current compressed noise channel along the offset distance, the azimuth angle, the line and the CDP.
Preferably, in the third embodiment of the present invention, as an implementation manner of the first embodiment: the maximum scan ranges of the currently compressed noise tracks along the offset, along the azimuth, along the line and along the CDP are different, and the scan intervals are also different. For example, the maximum scan range in the offset direction is 50 °, and the scan interval is 5 °; the maximum scanning range along the azimuth direction is 40 degrees, and the scanning interval is 4 degrees; the maximum scanning range along the line direction is 60 degrees, and the scanning interval is 10 degrees; the maximum scan range in the CDP direction is 55 ° and the scan interval is 11 °.
Thus, the number of scans along the offset, along the azimuth, along the line, and along the CDP for the currently compressed channel can be determined as 10, 6, and 5, respectively. The number of combinations of apparent tilt angles, i.e., 10 x 6 x 5 — 3000, can be determined by multiplying the number of scans in four directions. Correspondingly, a combination of apparent tilt angles may also be determined, which includes, for example, (5 °, 4 °, 10 °, 11 °) and (45 °, 36 °, 20 °, 33 °).
The calculation of the spectral values is, for example, according to the following expression:
f a, o, y, x, t represents the amplitude value of the current compressed noise channel at a certain sampling point along the azimuth angle a, the offset distance o, the line direction y, the CDP direction x and the time t under a certain dip angle combination; the numerator on the right side of the equation represents the square of the sum of the amplitudes and the denominator on the right side of the equation represents the product of the number of coverage M times and the sum of the squares of the amplitudes.
And calculating the spectral value of the current noise channel to be suppressed on the sampling point under different combinations of the apparent dip angles through the calculation. Then, the largest of these spectral values is selected as the largest correlation spectral value. And simultaneously, determining the view dip angle combination corresponding to the maximum correlation spectrum value.
And then, taking each noise-suppressed channel of the five-dimensional OVT body as a current noise-suppressed channel in turn, and forming a five-dimensional OVT channel set taking the channel as the center. And sequentially calculating the maximum correlation spectrum value of each pressed noise channel on the sampling point based on the spectrum value calculation formula, and determining the view dip angle combination corresponding to the maximum correlation spectrum value of each pressed noise channel, namely determining four optimal view dip angles of each pressed noise channel. Wherein the four optimal apparent dip angles include: an optimal apparent dip angle in the offset direction, an optimal apparent dip angle in the azimuthal direction, an optimal apparent dip angle in the linear direction, and an optimal apparent dip angle in the CDP direction.
And finally, stacking and denoising each channel to be denoised along the dip angle combination direction corresponding to the maximum correlation spectrum value of the channel to be denoised so as to suppress the noise of the seismic data.
Accordingly, the embodiment of the present invention further provides a storage medium, on which executable codes are stored, and when the executable codes are executed by a processor, the processor executes the seismic data five-dimensional spectrum analysis noise suppression method of the first to third embodiments.
Accordingly, an embodiment of the present invention further provides a computing device, including:
a processor; and
a memory having executable code stored thereon, which when executed by the processor, causes the processor to perform the seismic data five-dimensional spectral analysis noise suppression method of the first to third embodiments.
In summary, by applying the seismic data five-dimensional spectrum analysis noise suppression method, the storage medium and the computing device provided by the embodiment of the invention, the noise suppression capability is fully exerted by realizing the method in the five-dimensional OVT domain. For part of strong energy noise, the phenomenon of randomness is not necessarily shown on a conventional gather, and the traditional superposition denoising can not be realized. In the five-dimensional OVT trace set, the noise is more random, and the method can effectively suppress the noise of the type.
In addition, for data with a particularly low signal-to-noise ratio, the five-dimensional spectrum analysis noise suppression device can play a good role, has the amplitude maintaining function, is high in fidelity and does not generate the technical effect of construction artifacts.
Those skilled in the art will appreciate that the modules or steps of the invention described above can be implemented in a general purpose computing device, centralized on a single computing device or distributed across a network of computing devices, and optionally implemented in program code that is executable by a computing device, such that the modules or steps are stored in a memory device and executed by a computing device, fabricated separately into integrated circuit modules, or fabricated as a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.
Although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. A seismic data five-dimensional spectrum analysis noise suppression method comprises the following steps:
converting the three-dimensional shot-sharing gather into a pre-stack three-dimensional CDP gather by using a common depth point grid;
forming a rose diagram according to the position distribution density of the shot-picking coordinate central point in the prestack three-dimensional CDP channel set;
dividing the rose diagram into a plurality of offset vector pieces, and combining all the offset vector pieces into a five-dimensional OVT body; and
suppressing the noise of the seismic data by performing five-dimensional spectral analysis and superposition denoising on the five-dimensional OVT body, and suppressing the noise of the seismic data by performing five-dimensional spectral analysis and superposition denoising on the five-dimensional OVT body, including: in the five-dimensional OVT channel set, different dip angle combinations of the current pressed noise channel along the offset distance, the azimuth angle, the line and the CDP are determined, and the spectrum values of the current pressed noise channel on sampling points under different dip angle combinations are respectively calculated; selecting the largest of said spectral values as the largest correlation spectral value; and determining the view dip angle combination corresponding to the maximum correlation spectrum value.
2. The method of claim 1, wherein converting three-dimensional common shot gathers to prestack three-dimensional CDP gathers using a common depth point grid comprises:
and sequentially placing each seismic channel in the three-dimensional common shot point channel set in a common depth point grid according to the position of the shot detection coordinate central point to form the pre-stack three-dimensional CDP channel set.
3. The method of claim 1, wherein subdividing the rose diagram into a plurality of offset vector slices and combining all of the offset vector slices into a five-dimensional OVT volume comprises:
dividing the rose diagram into a plurality of sector surface elements by utilizing equally spaced concentric circles and bisectors passing through the circle center, wherein one sector surface element is one shot-geophone distance vector sheet; and
and sequentially arranging all the offset vector pieces to form the five-dimensional OVT body.
4. The method of claim 1, wherein denoising the seismic data by five-dimensional spectral analysis and stacking of the five-dimensional OVT volume comprises:
for each channel to be noise-suppressed in the five-dimensional OVT body, forming a five-dimensional OVT gather which takes the channel to be noise-suppressed as the center and contains all the channels to be noise-suppressed,
wherein the five-dimensional OVT gather comprises: offset bin number, azimuth bin number, CDP number, and line number.
5. The method of claim 1, wherein said different combinations of apparent dip angles are determined based on the maximum scan range and scan interval of the currently compressed channel in the four directions offset, azimuth, along line, and CDP.
6. The method of claim 1, wherein the spectral values are calculated according to the following expression:
wherein fa, o, y, x, t represents the amplitude value of the current channel at a certain sampling point along azimuth angle a, offset distance o, line direction y, CDP direction x and time t, the right-side numerator of the equation represents the square of the amplitude sum, and the right-side denominator of the equation represents the product of the coverage number M and the square of the amplitude sum.
7. The method of claim 1, wherein denoising the seismic data by five-dimensional spectral analysis and stacking of the five-dimensional OVT volume further comprises:
in the five-dimensional OVT gather, sequentially taking each compressed noise channel as the current compressed noise channel, calculating four optimal dip angles of each compressed noise channel, and carrying out superposition denoising along the directions of the four optimal dip angles to suppress the noise of the seismic data,
and the four optimal apparent dip angles are the apparent dip angle combination corresponding to the maximum correlation spectrum value.
8. A storage medium having stored thereon executable code which, when executed by a processor, causes the processor to perform the seismic data five-dimensional spectral analysis noise suppression method according to any one of claims 1 to 7.
9. A computing device, comprising:
a processor; and
a memory having executable code stored thereon which, when executed by the processor, causes the processor to perform the seismic data five-dimensional spectral analysis noise suppression method of any of claims 1 to 7.
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