阅读说明：本技术 一种基于冲击波激发震源的可变偏移距超前探测断层方法 (Variable offset distance advanced fault detection method based on shock wave excitation seismic source ) 是由 王勃 孙华超 刘盛东 龚震 李兴兴 王志丹 邢世雨 丁昕 张恒 张振东 于 2019-10-18 设计创作，主要内容包括：本发明公开了一种基于冲击波激发震源的可变偏移距超前探测断层方法,采用冲击波激发震源,将冲击波激发震源放置到一个钻孔内,利用冲击波激发震源多次激震的特点,通过改变不同孔深的方式分别进行激发,从而产生多个震源,且多个震源与检波器之间的偏移距均不相同,每次激发后地震观测系统获取一次共炮点道集,然后将各个共炮点道集进行处理,获取各个震源产生的反射槽波在本盘断层面上的最大振幅反射点位置；最后通过各个最大振幅反射点位置得出回归线性方程,将回归线性方程的直线显示在坐标系的XOY面上,该直线的位置即为断层位置；从而使工作人员直观的获取断层走向参数。(The invention discloses a variable offset distance advanced fault detection method based on shock wave excitation seismic sources, which comprises the steps of exciting the seismic sources by adopting shock waves, placing the shock wave excitation seismic sources into a drill hole, utilizing the characteristic that the shock waves excite the seismic sources for multiple times of shock excitation, and respectively exciting by changing different hole depths so as to generate a plurality of seismic sources, wherein the offset distances between the plurality of seismic sources and a detector are different, a common shot point gather is obtained by a seismic observation system after each time of excitation, then each common shot point gather is processed, and the position of a maximum amplitude reflection point of a reflection channel wave generated by each seismic source on a fault plane of a local disk is obtained; finally, obtaining a regression linear equation through the position of each maximum amplitude reflection point, and displaying a straight line of the regression linear equation on an XOY surface of a coordinate system, wherein the position of the straight line is the position of a fault; therefore, the staff can visually acquire the fault strike parameters.)

1. A fault detection method based on shock wave excitation seismic source variable offset distance advance is characterized by comprising the following specific steps:

the method comprises the following steps: constructing a drill hole at the position 2m away from the head of the coal roadway right side, wherein the length of the drill hole is N meters, and the drill hole is positioned in the middle of the coal seam and is parallel to a coal roadway top bottom plate;

step two: sending a shock wave excitation seismic source into the deepest part of the drilled hole;

step three: arranging m mounting holes on the right side of the coal roadway, wherein the distance between every two adjacent mounting holes is 3 meters, the positions of the mounting holes and the positions of drill holes are on the same horizontal plane, and a three-component detector is arranged in each mounting hole; each three-component detector is connected with an earthquake recorder, and a coal roadway tunneling advanced prediction observation system is established;

step four: the shock wave excitation seismic source is excited for the first time from the deepest part of the drill hole, and then is excited every 2m from inside to outside for n times in total to form a seismic source S₁、S₂、S₃...S_nEach three-component detector receives seismic waves generated by each seismic source in real time and transmits the seismic waves to a seismic recorder;

step five: establishing a three-dimensional coordinate system along a coal roadway, wherein the X direction is the direction towards the head, the Y direction is perpendicular to the coal wall and perpendicular to the direction towards the head, the Z direction is perpendicular to the top bottom plate of the roadway and perpendicular to the direction towards the head, the center of the roadway surface on the left boundary of the model is used as an origin to establish the three-dimensional coordinate system, and each seismic source position and each three-component detector position are included in the three-dimensional coordinate system;

step six: each seismic source generates a three-component common shot point gather, n three-component common shot point gathers are generated in total, each common shot point gather is analyzed, a reflection slot wave signal from the fault plane of the disc is selected from the common shot point gathers, and the maximum amplitude reflection point of each common shot point gather on the fault plane of the disc is obtained and is A₁，A₂，A₃...A_n；

Step seven: all maximum amplitude reflection points are classified into an XOY surface of a three-dimensional coordinate system, and the coordinates of the reflection points are A₁(x₁，y₁)、A₂(x₂，y₂)，A₃(x₃，y₃)...A_n(x_n，y_n) Solving a regression linear equation of the linear equation;

step eight: and forming a straight line on the XOY plane according to the regression linear equation obtained in the step seven, namely the fault position, so as to determine the fault trend.

2. The method for variable offset advanced fault detection based on the shock wave excitation seismic source according to claim 1, wherein the specific process of the sixth step is as follows:

(1) extracting seismic source S₁The generated common shot gather selects a time window t with three-component reflected channel wave signals₁；

(2) From the time window t₁Selecting three-component seismic waves of the duration t of the Ehry phase from the reflected channel wave signals to analyze;

(3) and (3) calculating the three-component seismic waves with the duration t in the step (2) to obtain the polarization parameters of the three-component seismic waves, and specifically comprising the following steps:

I. the Hilbert transform is performed on X, Y, Z three component seismic signals as follows:

in the formula: x (t), y (t), z (t) X, Y, Z components and symbols respectively

II. Establishing a Hermitian matrix structure:

C(t)＝M*(t)·M(t)

wherein m (t) ([ hx (t)' hy (t) ()) hz (t) ], and the symbol denotes a complex conjugate transpose of the matrix;

III, solving to obtain a maximum characteristic value lambda₁With main polarization direction centered on the eigenvalue λ₁In the direction of the characteristic vector, the normalized characteristic vector is obtained and expressed as [ x ]₁(t)，y₁(t)，z₁(t)]；

IV, azimuth of the main polarization direction is expressed as:

v, carrying out amplitude calculation according to the parameters, wherein the formula is as follows:

where Ω represents all traces of n sources corresponding to m three-component detectors, A (t, f) represents a stacking function of scalar amplitudes at a certain frequency_iRepresents the amplitude energy, L_s+L_RRepresenting the total path of propagation of the seismic waves, V_CRepresenting the wave velocity of the trough wave airy phase, and x, y and z represent the positions of each seismic source and the three-component detector; weight function C of the main polarization direction_iThe expression is as follows:

through C_iLeft and right artifacts in amplitude calculation can be eliminated, so that whether the position of a reflection point is in the positive Y direction or the negative Y direction is directly determined;

(6) through the above (1) to (5), the position of the maximum amplitude reflection point of the reflection groove wave on the sectional plane of the disc can be determined and recorded as A₁；

(7) The co-shot gathers of other seismic sources are analyzed,repeating the steps (1) to (6) to obtain other maximum amplitude reflection points A₂，A₃，A₄…A_n。

3. The method for variable offset advanced fault detection based on shock wave excitation seismic source according to claim 1, wherein the concrete process of the seventh step is as follows:

(1) all maximum amplitude reflection points are classified into an XOY surface of a three-dimensional coordinate system, and the coordinate is A₁(x₁，y₁)、A₂(x₂，y₂)、A₃(x₃，y₃)...A_n(x_n，y_n)；

(2) Respectively obtaining:

(3) obtaining a regression linear equation through the parameters in the step (2):

Technical Field

The invention relates to a mine geophysical detection method, in particular to a variable offset distance advanced fault detection method based on a shock wave excitation seismic source.

Background

Frequent coal roadway tunneling accidents always disturb the safety production of coal mines, wherein water inrush or coal and gas outburst disaster accidents caused by geological structures are mainly caused by the fact that the fault detection precision in front of the head is poor; the problem of 'the diameter of a hole' in underground drilling cannot fully understand the front geological structure, and the cost is high; the geophysical method can detect the front fault structure, wherein the seismic advanced detection method is the main method for coal mine geological exploration at present; at present, fault fall, inclination, dip angle and other parameter technologies are solved, but the fault strike parameters are difficult to calculate due to the limitation of roadway seismic advanced detection minimum offset aperture.

The seismic source in the seismic advance detection is an important link for determining whether the seismic advance detection is successful or not; the energy of a traditional percussion hammer seismic source is weak; although the explosive seismic source can meet the requirement of earthquake advanced detection, the explosive seismic source is limited to coal mine conditions and the approval process is complex, so that the development of a novel seismic source is imminent; the application number CN201811061977.9 patent provides a novel CO used for the exploration method of earthquake transmission groove waves of high gas mines₂The cannon can meet the requirement of underground exploration of a coal mineThe seismic source is a clean seismic source, and the limitation of a high gas mine to the explosive seismic source is solved; but CO₂The cannon excitation instrument is subjected to CO₂The reservoir is limited and difficult to circulate through the borehole.

The method and the system for the advanced detection of the groove wave of the underground single-head roadway based on the hole-roadway combination, which are proposed by the patent No. CN108121010B, improve the accuracy of the groove wave reflected by the roadway by arranging the wave detectors in holes and arranging the wave detectors at left and right sides of the roadway in left and right coal seams, but the method needs 2 deep-hole wave detectors, has large workload, and needs to research a new method to reduce the number of drilled holes so as to improve the efficiency; in addition, the method also needs to manually explain the fault strike parameters according to the offset imaging section, the explanation difference of personnel with different technical levels is large, the explanation deviation is easy to cause, and a new method with intuitive detection results and easy identification is urgently needed.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a variable offset distance advanced fault detection method based on a shock wave excitation seismic source, which can display the fault position in a coordinate system by exciting the seismic source for multiple times, so that a worker can intuitively acquire fault trend parameters and the development of subsequent work is facilitated.

In order to achieve the purpose, the invention adopts the technical scheme that: a fault detection method based on shock wave excitation seismic source variable offset distance advance comprises the following specific steps:

the method comprises the following steps: constructing a drill hole at the position 2m away from the head of the coal roadway right side, wherein the length of the drill hole is N meters, and the drill hole is positioned in the middle of the coal seam and is parallel to a coal roadway top bottom plate;

step two: sending a shock wave excitation seismic source into the deepest part of the drilled hole;

step three: arranging m mounting holes on the right side of the coal roadway, wherein the distance between every two adjacent mounting holes is 3 meters, the positions of the mounting holes and the positions of drill holes are on the same horizontal plane, and a three-component detector is arranged in each mounting hole; each three-component detector is connected with an earthquake recorder, and a coal roadway tunneling advanced prediction observation system is established;

step four: shock wave excited vibrationThe source is excited for the first time from the deepest part of the borehole and then is excited every 2m from the inside to the outside for a total of n times to form a seismic source S₁、S₂、S₃…S_nEach three-component detector receives seismic waves generated by each seismic source in real time and transmits the seismic waves to a seismic recorder;

step five: establishing a three-dimensional coordinate system along a coal roadway, wherein the X direction is the direction towards the head, the Y direction is perpendicular to the coal wall and perpendicular to the direction towards the head, the Z direction is perpendicular to the top bottom plate of the roadway and perpendicular to the direction towards the head, the center of the roadway surface on the left boundary of the model is used as an origin to establish the three-dimensional coordinate system, and each seismic source position and each three-component detector position are included in the three-dimensional coordinate system;

step six: each seismic source generates a three-component common shot point gather, n three-component common shot point gathers are generated in total, each common shot point gather is analyzed, a reflection slot wave signal from the fault plane of the disc is selected from the common shot point gathers, and the maximum amplitude reflection point of each common shot point gather on the fault plane of the disc is obtained and is A₁，A₂，A₃…A_n；

Step seven: all maximum amplitude reflection points are classified into an XOY surface of a three-dimensional coordinate system, and the coordinates of the reflection points are A₁(x₁，y₁)、A₂(x₂，y₂)，A₃(x₃，y₃)…A_n(x_n，y_n) Solving a regression linear equation of the linear equation;

step eight: and forming a straight line on the XOY plane according to the regression linear equation obtained in the step seven, namely the fault position, so as to determine the fault trend.

Further, the specific process of the sixth step is as follows:

(1) extracting seismic source S₁The generated common shot gather selects a time window t with three-component reflected channel wave signals₁；

(2) From the time window t₁Selecting three-component seismic waves of the duration t of the Ehry phase from the reflected channel wave signals to analyze;

(3) and (3) calculating the three-component seismic waves with the duration t in the step (2) to obtain the polarization parameters of the three-component seismic waves, and specifically comprising the following steps:

i, carrying out Hilbert transformation on X, Y, Z three-component seismic signals as follows:

in the formula: x (t), y (t), z (t) X, Y, Z components and symbols respectively

Which represents the Hilbert transform, is,

II, establishing a Hermitian matrix structure:

C(t)＝M*(t)·M(t)

wherein m (t) ([ hx (t)' hy (t) ()) hz (t) ], and the symbol denotes a complex conjugate transpose of the matrix;

III, solving to obtain the maximum characteristic value lambda₁With main polarization direction centered on the eigenvalue λ₁In the direction of the characteristic vector, the normalized characteristic vector is obtained and expressed as [ x ]₁(t)，y₁(t)，z₁(t)]；

IV, the azimuth angle of the main polarization direction is expressed as:

v, carrying out amplitude calculation according to the parameters, wherein the formula is as follows:

where Ω represents all traces of n sources corresponding to m three-component detectors, A (t, f) represents a stacking function of scalar amplitudes at a certain frequency_iRepresents the amplitude energy, L_s+L_RRepresenting the total path of propagation of the seismic waves, V_CRepresenting the wave velocity of the trough wave airy phase, and x, y and z represent the positions of each seismic source and the three-component detector; weight function C of the main polarization direction_iThe expression is as follows:

through C_iLeft and right artifacts in amplitude calculation can be eliminated, so that whether the position of a reflection point is in the positive Y direction or the negative Y direction is directly determined;

(6) through the above (1) to (5), the position of the maximum amplitude reflection point of the reflection groove wave on the sectional plane of the disc can be determined and recorded as A₁；

(7) Analyzing the common shot gather of other seismic sources, repeating the steps (1) to (6) to obtain other maximum amplitude reflection points A₂，A₃，A₄…A_n。

Further, the specific process of the seventh step is as follows:

(1) all maximum amplitude reflection points are classified into an XOY surface of a three-dimensional coordinate system, and the coordinate is A₁(x₁，y₁)、A₂(x₂，y₂)、A₃(x₃，y₃)…A_n(x_n，y_n)；

(2) Respectively obtaining:

(3) obtaining a regression linear equation through the parameters in the step (2):

thereby ensuring that as many reflection points as possible are on or near the straight line.

Compared with the prior art, the method adopts shock waves as seismic sources, the shock wave seismic sources are placed in the drill holes, the multiple excitation of the shock wave seismic sources is utilized, the multiple excitation is respectively carried out by changing different hole depths, so that a plurality of seismic sources are generated, the offset distances between the plurality of seismic sources and the detectors are different, after each excitation, the seismic observation system acquires a common shot point gather once, then each common shot point gather is processed, and the maximum amplitude reflection point position of reflection channel waves generated by each seismic source on a fault interface is acquired; finally, obtaining a regression linear equation through the position of each maximum amplitude reflection point, and displaying a straight line of the regression linear equation on an XOY surface of a coordinate system, wherein the position of the straight line is the position of a fault; therefore, the staff can visually know the detected fault position, and the subsequent work can be conveniently carried out. In addition, the seismic source adopted by the invention has fewer and safer inspection procedures than the traditional explosive seismic source, and is more CO-safe than the traditional explosive seismic source₂The cannon seismic source can be recycled for multiple times; the method only needs to construct one drilling hole, and the efficiency is doubled compared with the prior art.

Drawings

FIG. 1 is a schematic view of the arrangement of the observation system in the present invention;

FIG. 2 is a scatter plot of a reflection point image obtained using the present invention.

In the figure: 1. the system comprises a coal roadway, a three-component detector, a detector 3, a head-on detector, a shock wave excitation seismic source 4 and a fault.

Detailed Description

The present invention will be further explained below.

As shown in the figure, the method comprises the following specific steps:

the method comprises the following steps: constructing a drill hole at the position of the right side of the coal roadway 1, which is 2m away from the head, wherein the length of the drill hole is N meters, and the drill hole is positioned in the middle of the coal seam and is parallel to the top floor of the coal roadway;

step two: sending the shock wave excitation seismic source 4 into the deepest part of the drilled hole;

step three: the method comprises the following steps that m mounting holes are distributed on the right side of a coal roadway 1, the distance between every two adjacent mounting holes is 3 m, the positions of all the mounting holes and a drill hole are located on the same horizontal plane, and a three-component detector 2 is uniformly distributed in each mounting hole; each three-component detector 2 is connected with an earthquake recorder, and a coal roadway tunneling advanced prediction observation system is established;

step four: the shock wave excitation seismic source 4 carries out first excitation from the deepest part of the drill hole, and then the shock wave excitation seismic source is excited once every 2m from inside to outside for n times in total to form a seismic source S₁、S₂、S₃…S_nEach three-component wave detector 2 receives seismic waves generated by each seismic source in real time and transmits the seismic waves to a seismic recorder;

step five: establishing a three-dimensional coordinate system along a coal roadway, wherein the X direction is the direction towards the head, the Y direction is perpendicular to the coal wall and perpendicular to the direction towards the head, the Z direction is perpendicular to the top bottom plate of the roadway and perpendicular to the direction towards the head, the center of the roadway surface on the left boundary of the model is used as an origin to establish the three-dimensional coordinate system, and each seismic source position and each three-component detector position are included in the three-dimensional coordinate system;

step six: each seismic source generates a three-component common shot point gather, n three-component common shot point gathers are generated in total, each common shot point gather is analyzed, a reflection slot wave signal from the fault plane of the disc is selected from the common shot point gathers, and each common shot point gather is solved in the local shot point gatherMaximum amplitude reflection points on the disc fault plane are respectively A₁，A₂，A₃…A_n；

Step seven: all maximum amplitude reflection points are classified into an XOY surface of a three-dimensional coordinate system, and the coordinates of the reflection points are A₁(x₁，y₁)、A₂(x₂，y₂)，A₃(x₃，y₃)…A_n(x_n，y_n) Solving a regression linear equation of the linear equation;

step eight: and forming a straight line on the XOY plane according to the regression linear equation obtained in the step seven, namely the position of the fault 5, so as to determine the trend of the fault 5.

Further, the specific process of the sixth step is as follows:

(1) extracting seismic source S₁The generated common shot gather selects a time window t with three-component reflected channel wave signals₁；

(2) From the time window t₁Selecting three-component seismic waves of the duration t of the Ehry phase from the reflected channel wave signals to analyze;

(3) and (3) calculating the three-component seismic waves with the duration t in the step (2) to obtain the polarization parameters of the three-component seismic waves, and specifically comprising the following steps:

i, carrying out Hilbert transformation on X, Y, Z three-component seismic signals as follows:

in the formula: x (t), y (t), z (t) X, Y, Z components and symbols respectively

Which represents the Hilbert transform, is,

II, establishing a Hermitian matrix structure:

C(t)＝M*(t)·M(t)

wherein m (t) ([ hx (t)' hy (t) ()) hz (t) ], and the symbol denotes a complex conjugate transpose of the matrix;

III, solving to obtain the maximum characteristic value lambda₁With main polarization direction centered on the eigenvalue λ₁In the direction of the characteristic vector, the normalized characteristic vector is obtained and expressed as [ x ]₁(t)，y₁(t)，z₁(t)]；

IV, the azimuth angle of the main polarization direction is expressed as:

v, carrying out amplitude calculation according to the parameters, wherein the formula is as follows:

where Ω represents all traces of n sources corresponding to m three-component detectors, A (t, f) represents a stacking function of scalar amplitudes at a certain frequency_iRepresents the amplitude energy, L_s+L_RRepresenting the total path of propagation of the seismic waves, V_CRepresenting the wave velocity of the trough wave airy phase, and x, y and z represent the positions of each seismic source and the three-component detector; weight function C of the main polarization direction_iThe expression is as follows:

through C_iLeft and right artifacts in amplitude calculation can be eliminated, so that whether the position of a reflection point is in the positive Y direction or the negative Y direction is directly determined;

(6) through the above (1) to (5), the position of the maximum amplitude reflection point of the reflection groove wave on the sectional plane of the disc can be determined and recorded as A₁；

(7) Analyzing the common shot gather of other seismic sources, repeating the steps (1) to (6) to obtain other maximum amplitude reflection points A₂，A₃，A₄…A_n。

Further, the specific process of the seventh step is as follows:

(1) all maximum amplitude reflection points are classified into an XOY surface of a three-dimensional coordinate system, and the coordinate is A₁(x₁，y₁)、A₂(x₂，y₂)、A₃(x₃，y₃)…A_n(x_n，y_n)；

(2) Respectively obtaining:

(3) obtaining a regression linear equation through the parameters in the step (2):

thereby ensuring that as many reflection points as possible are on or near the straight line.