阅读说明：本技术 一种针对倾斜金属矿体成像方法 (Imaging method for inclined metal ore body ) 是由 胡斌 张峻铭 于 2021-08-19 设计创作，主要内容包括：本发明公开了一种针对倾斜金属矿体成像方法,具体包括以下步骤：S1、将采集的炮集域双曲线形式地震数据进行预处理；S2、将预处理后的地震数据进行处理域转换,得到拉冬域形式地震数据及对应的速度参数；S3、基于预处理后的地震数据和拉冬域形式地震数据,对拉冬域形式地震数据中的顶点进行约束；S4、对约束后的顶点进行动校验证；S5、确定动校验证合格后的顶点是否充足；S6、对每炮地震数据震源点附近范围内的顶点进行成像范围排除,利用剩余的绕射波数据与对应的速度参数进行成像,得到倾斜金属矿体的成像结果。本发明将作为小尺度、不连续地质体直接指示的绕射波用于成像,可以比传统反射波成像方法呈现更好的效果。(The invention discloses an imaging method for an inclined metal ore body, which specifically comprises the following steps: s1, preprocessing the acquired shot domain hyperbolic form seismic data; s2, performing processing domain conversion on the preprocessed seismic data to obtain Ladong domain form seismic data and corresponding velocity parameters; s3, based on the preprocessed seismic data and the seismic data in the Ladong domain form, constraining vertexes in the seismic data in the Ladong domain form; s4, performing dynamic correction verification on the constrained vertex; s5, determining whether the vertexes qualified by dynamic calibration verification are sufficient; and S6, eliminating the imaging range of the top point in the range near the seismic source point of each shot of seismic data, and imaging by using the residual diffracted wave data and the corresponding velocity parameter to obtain the imaging result of the inclined metal ore body. The diffraction wave directly indicated by the small-scale discontinuous geologic body is used for imaging, and the method has a better effect than the traditional reflected wave imaging method.)

1. An imaging method for an inclined metal ore body is characterized by comprising the following steps:

s1, collecting hyperbolic seismic data of a shot gather domain as original seismic data, and preprocessing the original seismic data;

s2, performing processing domain conversion on the preprocessed seismic data to obtain Ladong domain form seismic data and corresponding velocity parameters;

s3, constraining vertexes in the seismic data in the Ladong domain form based on the preprocessed seismic data and the seismic data in the Ladong domain form;

s4, performing dynamic correction verification on the constrained vertex;

s5, determining whether the vertexes qualified by dynamic calibration verification are sufficient;

and S6, based on the S5, eliminating the imaging range of the top point in the range near the seismic source point of each shot of seismic data, and imaging by using the residual diffracted wave data and the corresponding velocity parameter to obtain the imaging result of the inclined metal ore body.

2. The method for imaging tilted metal ore bodies according to claim 1, wherein the preprocessing of the raw seismic data is specifically:

and carrying out noise suppression on the original seismic data through median filtering, and carrying out effective signal enhancement by using a Gaussian derivative operator.

3. The method of claim 1, wherein the preprocessed seismic data are processed domain transformed using a vertex-shifting radon transform.

4. The method of claim 3, wherein the vertex shift radon transform is expressed as:

wherein f (i, j) is seismic data in a hyperbolic form of the converted forward shot domain, and i and j are respectively the horizontal axis and the vertical axis coordinates of the hyperbolic curve of the converted forward shot domain; delta is a dirac function; xi is a number having three parameters (i)₀,j₀V) hyperbolic path; m (i)₀,j₀) For the final acquired seismic data in Ladong Domain form i₀And j₀Respectively the horizontal axis and the vertical axis of the converted shot domain hyperbola; dx is the spacing of the detectors; dt is the sampling interval of the detector; (i)₀,j₀) The hyperbolic vertex position; j is a function of_sIs the seismic source location; j is a function of_rIs the detector position; v is the root mean square velocity.

5. The method for imaging a tilted metal ore body according to claim 1, wherein the S3 is specifically:

and calculating a local similarity coefficient according to the preprocessed seismic data and the seismic data in the LaDong domain form, constructing a threshold function according to the local similarity coefficient, reserving the seismic data which are higher than the threshold, keeping the assignment value which is lower than the threshold to be zero, and sequentially constraining vertexes in the seismic data in the LaDong domain form, which are obtained by vertex movement LaDong change.

6. The method for imaging a tilted metal ore body according to claim 5, wherein the calculation expression of the local similarity coefficient is:

L₁＝[λ₁ ²I+S(M_j ^TM_j-λ₁ ²I)]^-1SM_j ^Tf_j··········(4)

L₂＝[λ₂ ²I+S(F_j ^TF_j-λ₂ ²I)]^-1SF_j ^Tm_j··········(5)

wherein, Local is the obtained Local correlation coefficient; l is₁、L₁Respectively intermediate variables; f. of_jOne pass representing the input shot gather data; m is_jIs one track of the input Latin field data; f_j、M_jIn the form of a diagonal matrix of data; i is dimension and M_j ^TM_jThe same identity matrix; s is a smooth operator; lambda [ alpha ]₁、λ₂Respectively, are parameters that control the inversion speed.

7. The method of imaging a dipping metal ore body according to claim 5, wherein the computational expression of the threshold function is:

wherein, Apex (t, x) is the spatial position of the vertex obtained by the high-pass low-cut processing of the local similar spectrum; s_hIs a high-pass threshold parameter; s_lIs a low cutoff threshold parameter.

8. The method for imaging a tilted metal ore body according to claim 1, wherein the S4 is specifically:

performing dynamic calibration verification on the hyperbola and the speed parameter corresponding to the constrained vertex, and observing whether the hyperbola is leveled or not; if the leveling is successful, the selection speed is proper; otherwise, the speed is reselected.

9. The method for imaging a tilted metal ore body according to claim 1, wherein the S5 is specifically:

determining whether the vertexes qualified by dynamic calibration verification are sufficient, and if so, executing S6; if not, removing the seismic curve with the vertex position taken out from the original data, and repeating S2-S5 by taking the new data as input data until sufficient vertices and corresponding velocity parameters are obtained.

Technical Field

The invention relates to the technical field of metal ore seismic exploration, in particular to an imaging method for an inclined metal ore body.

Background

In recent years, the exploration and development of metal minerals gradually change to deep parts, and compared with the conventional metal mineral exploration technology, the seismic exploration technology can explore underground deep structures according to the kinematics and dynamics characteristics of seismic waves and depict the distribution of deep mineral bodies, thereby becoming an important means for deep metal mineral exploration.

In metal ore exploration, ore bodies are small in scale and irregular in shape, particularly when the dip angle of the ore bodies is large, a reflection wave imaging method generally adopted in seismic exploration mainly reflects the characteristics of a large-scale structure and a continuous geological interface, and the fine structure of the ore bodies cannot be described.

Therefore, it is highly desirable to have a method for imaging an inclined metal ore body to characterize the fine structure of the ore body, which is a topic popular with researchers.

Disclosure of Invention

The invention aims to provide an imaging method for an inclined metal ore body, which aims to solve the problem that the traditional reflected wave imaging method cannot depict the fine structure of the ore body when the inclination angle of the ore body is larger by improving the seismic wave imaging process.

In order to achieve the above object, the present invention provides an imaging method for an inclined metal ore body, which specifically comprises the following steps:

s1, collecting hyperbolic seismic data of a shot gather domain as original seismic data, and preprocessing the original seismic data;

s2, performing processing domain conversion on the preprocessed seismic data to obtain Ladong domain form seismic data and corresponding velocity parameters;

s3, constraining vertexes in the seismic data in the Ladong domain form based on the preprocessed seismic data and the seismic data in the Ladong domain form;

s4, performing dynamic correction verification on the constrained vertex;

s5, determining whether the vertexes qualified by dynamic calibration verification are sufficient;

and S6, based on the S5, eliminating the imaging range of the top point in the range near the seismic source point of each shot of seismic data, and imaging by using the residual diffracted wave data and the corresponding velocity parameter to obtain the imaging result of the inclined metal ore body.

Preferably, the preprocessing of the original seismic data specifically comprises:

and carrying out noise suppression on the original seismic data through median filtering, and carrying out effective signal enhancement by using a Gaussian derivative operator.

Preferably, the preprocessed seismic data are processed by domain conversion using vertex-shifting radon transform.

Preferably, the expression of the vertex moving radon transform is as follows:

wherein f (i, j) is seismic data in a hyperbolic form of the converted forward shot domain, and i and j are respectively the horizontal axis and the vertical axis coordinates of the hyperbolic curve of the converted forward shot domain; delta is a dirac function; xi is a number having three parameters (i)₀,j₀V) hyperbolic path; m (i)₀,j₀) For the final acquired seismic data in Ladong Domain form i₀And j₀Respectively the horizontal axis and the vertical axis of the converted shot domain hyperbola; dx is the spacing of the detectors; dt is the sampling interval of the detector; (i)₀,j₀) The hyperbolic vertex position; j is a function of_sIs the seismic source location; j is a function of_rIs the detector position; v is the root mean square velocity.

Preferably, the S3 is specifically:

and calculating a local similarity coefficient according to the preprocessed seismic data and the seismic data in the LaDong domain form, constructing a threshold function according to the local similarity coefficient, reserving the seismic data which are higher than the threshold, keeping the assignment value which is lower than the threshold to be zero, and sequentially constraining vertexes in the seismic data in the LaDong domain form, which are obtained by vertex movement LaDong change.

Preferably, the calculation expression of the local similarity coefficient is as follows:

L₁＝[λ₁ ²I+S(M_j ^TM_j-λ₁ ²I)]^-1SM_j ^Tf_j··········(4)

L₂＝[λ₂ ²I+S(F_j ^TF_j-λ₂ ²I)]^-1SF_j ^Tm_j··········(5)

wherein, Local is the obtained Local correlation coefficient; l is₁、L₁Respectively intermediate variables; f. of_jOne pass representing the input shot gather data; m is_jIs one track of the input Latin field data; f_j、M_jIn the form of a diagonal matrix of data; i is dimension and M_j ^TM_jThe same identity matrix; s is a smooth operator; lambda [ alpha ]₁、λ₂Respectively, are parameters that control the inversion speed.

Preferably, the calculation expression of the threshold function is:

wherein, Apex (t, x) is the spatial position of the vertex obtained by the high-pass low-cut processing of the local similar spectrum; s_hIs a high-pass threshold parameter; s_lIs a low cutoff threshold parameter.

Preferably, the S4 is specifically:

performing dynamic calibration verification on the hyperbola and the speed parameter corresponding to the constrained vertex, and observing whether the hyperbola is leveled or not; if the leveling is successful, the selection speed is proper; otherwise, the speed is reselected.

Preferably, the S5 is specifically:

determining whether the vertexes qualified by dynamic calibration verification are sufficient, and if so, executing S6; if not, removing the seismic curve with the vertex position taken out from the original data, and repeating S2-S5 by taking the new data as input data until sufficient vertices and corresponding velocity parameters are obtained

Compared with the prior art, the invention has the following technical effects:

the invention does not adopt the traditional reflected seismic wave imaging method any more, selects the diffracted wave from the imaged effective signal by modifying the imaging process, successfully utilizes the advantage that the diffracted wave is good at depicting small-scale discontinuous geologic bodies, and solves the problems that the ore body has small scale and irregular shape in metal ore exploration, and particularly the internal structure of the ore body can not be depicted when the dip angle of the ore body is larger.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a flow chart of the method of the present invention;

FIG. 2 is a schematic view of a model of a tilted metal ore body according to an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating a vertex validation process according to an embodiment of the present invention; wherein, (a) is the original input data diagram; (b) a data plot of seismic event axes selected for the first time; (c) a map of vertex positions determined for the event axes;

FIG. 4 is a diagram of verification results of dynamic calibration according to an embodiment of the present invention; wherein, (a) is a result graph of dynamic correction of the same-phase axis by using a speed of 3500 m/s; (b) the result graph of dynamic correction is carried out by using the speed of 4100 m/s; (c) the result graph of the dynamic correction is carried out by using the speed of 6000 m/s;

FIG. 5 is a diagram illustrating vertex picking results according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Example 1

Referring to fig. 1, the invention provides an imaging method for an inclined metal ore body, and the method is applied to an inclined metal ore body model test, and referring to fig. 2, the track spacing (the distance between detectors) is 20m, the shot spacing is also 20, the detectors do not move and the shots move, and the sampling interval is 0.002 s.

The method specifically comprises the following steps:

s1, collected data and data preprocessing: collecting hyperbolic seismic data of a shot gather domain as original seismic data; and the collected original seismic data is preprocessed in an early stage, so that noise is suppressed, and effective signals are enhanced. The invention selects median filtering to suppress noise and utilizes a Gaussian derivative operator to enhance effective signals.

S2, processing domain conversion: and performing vertex moving radon transform on the preprocessed shot gather domain hyperbolic form seismic data, wherein when the selected velocity is appropriate, the hyperbolic curve can be converged, the converged position is the position of a geological body, and the radon domain form of the seismic data and the velocity parameter corresponding to the radon domain form can be obtained through the vertex moving radon transform.

The vertex moving radon transformation expression is as follows:

wherein, because the traditional shot gather domain usually takes time as a vertical axis and distance as a horizontal axis, (i, j) is the coordinate of a hyperbola of the conversion front shot gather domain, i is the vertical axis and j is the coordinate of the horizontal axis; f (i, j) is the hyperbolic form seismic data of the shot domain; delta is a dirac function and xi is a function having three parameters (i)₀,j₀V) hyperbolic path; (i)₀,j₀) To transform the location of the vertex of the Law-winter domain hyperbola, i₀Is a coordinate in the direction of the longitudinal axis, j₀Is a horizontal axis coordinate; m (i)₀,j₀) The seismic data in the form of the Ladong domain is finally obtained; dx is the spacing of the detectors; dt is the sampling interval of the detector; j is a function of_sAt the source location, the surface excitation is considered at the source, the depth is 0, so j_sRepresenting its location on the earth's surface; j is a function of_rFor detector position, the detector depth of burial is also considered to be 0 in the survey, so j_rRepresenting the position information of the detector on the ground surface; v is the root mean square velocity.

S3, vertex constraint: due to the complexity of actual data, the vertex movement pull transformation cannot perfectly converge the data into a point, in order to obtain more accurate positions, local similarity coefficients are obtained for preprocessed shot gather domain hyperbolic seismic data (namely shot gather data) and radon domain seismic data (namely radon domain data), a threshold function is constructed according to the local similarity coefficients, the value higher than a threshold value is reserved, the value lower than the threshold value is zero, and vertices which are obtained by vertex movement radon change are sequentially restrained.

The calculation expression of the local similarity coefficient is as follows:

L₁＝[λ₁ ²I+S(M_j ^TM_j-λ₁ ²I)]^-1SM_j ^Tf_j··········(4)

L₂＝[λ₂ ²I+S(F_j ^TF_j-λ₂ ²I)]^-1SF_j ^Tm_j··········(5)

wherein, Local is the obtained Local correlation coefficient; l is₁、L₁Respectively intermediate variables; f. of_jOne pass representing the input shot gather data; m is_jFor incoming Ladong field dataOne step is carried out; f_j、M_jIn the form of a diagonal matrix of data; i is dimension and M_j ^TM_jThe same identity matrix; s is a smooth operator; lambda [ alpha ]₁、λ₂Respectively, parameters for controlling inversion speed, typically taking F_j、M_j10% of the maximum eigenvalue of (d);

the expression of the threshold function is:

wherein, Apex (t, x) is the spatial position of the vertex obtained by the high-pass low-cut processing of the local similar spectrum; s_hIs a high-pass threshold parameter; s_lIs a low cutoff threshold parameter. The selection of specific values can be adjusted according to the situation, the higher the high-pass threshold is set, the stricter the reserved requirements are, and the vertex confirmation process is shown by referring to fig. 3, wherein fig. 3(a) is an original input data graph; FIG. 3(b) is a data plot of a first selected seismic event; FIG. 3(c) is a diagram of the vertex positions determined by the in-phase axes.

S4, dynamic correction verification: and performing dynamic correction on the hyperbola corresponding to the vertex by using the corresponding speed parameter, and observing whether the hyperbola is leveled or not. If the leveling is successful, the selected speed is proper, otherwise, the speed needs to be selected again, and a dynamic correction verification result graph shown in fig. 4 is referred to, wherein fig. 4(a) is a result graph of dynamic correction on the same-phase axis by using the speed of 3500 m/s; (b) is a graph of the results of the kinetic correction using a velocity of 4100 m/s; (c) as a result of the dynamic correction using the velocity of 6000m/s, it can be seen from FIG. 4 that only when the velocity is selected to be 4100m/s, which is preferable, the hyperbola is leveled, and neither the velocity is too large nor too small, the hyperbola is leveled. Experimental results show that the in-phase axis can only be leveled if the applied dynamic correction velocity is in accordance with the formation velocity.

S5, determining whether the vertexes qualified by dynamic calibration verification are sufficient, and if so, executing S6; if not, performing iterative calculation, removing the seismic curve with the vertex position taken out from the original data, and repeating S2-S5 by taking the new data as input data until enough vertices and corresponding velocity parameters are taken out.

S6, diffraction wave imaging: and eliminating an imaging range from vertexes in a certain range near the seismic source point of each shot data to complete the separation of the reflected wave and the diffracted wave, and imaging by using the residual diffracted wave data and the corresponding speed parameters to obtain a better imaging result of the inclined metal ore body. The final result is shown in fig. 5, wherein the small circles are diffraction wave points picked up and well matched with the model, and imaging is performed through the points, so that better imaging results than the traditional reflected wave imaging can be obtained.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.