CN114280669A - Refractive wave period amplitude attenuation-based thin coal belt detection method and system - Google Patents
Refractive wave period amplitude attenuation-based thin coal belt detection method and system Download PDFInfo
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Abstract
The invention discloses a method and a system for detecting a thin coal belt based on refraction wave period amplitude attenuation, which comprises the following steps: and (S1) arranging instruments: the seismic survey line consists of S excitation points and R receiving points; seismic data d with the total channel number of N is formed between the excitation point and the receiving point through signal acquisition and data transmissioni(t); s2, acquiring formation data and calculating to obtain a refracted wave period: obtaining longitudinal wave velocity v of surrounding rockrAnd coal bed longitudinal wave velocity vcMeasuring the thickness h of the coal seam exposed by the roadway at the side wall of the roadway, and calculating the period T of the refracted wave; s3 for di(t) processing to obtain seismic data s after deconvolution and intra-track equalizationi(t); determining seismic data si(t) and reference track s0(t) at npAmplitude ratio of order as refractive wave period amplitude coefficient a of P pointp，apThe magnitude of (c) reflects the thickness of the coal seam at point P. Refracted waves of coal bed used by the inventionThe method is another underground seismic wave generated simultaneously with the trough wave, and the refracted wave is used for explaining the thin coal belt boundary more accurately, so that the coal mine stoping work efficiency and the resource utilization rate are improved.
Description
Technical Field
The invention belongs to the technical field of coal field geophysical prospecting, and relates to an underground geophysical prospecting method and system for detecting a thin coal zone in a coal face. The method separates refracted waves from seismic waves excited and received in a coal bed, and estimates the boundary detection method of the thin coal zone by using the attenuation degree of the periodic amplitude of the refracted waves.
Background
The thin coal zone is an area with the thickness reduced due to the fact that the bottom projection of the coal layer is thinned or the coal layer is influenced by river erosion. The existence of the thin coal zone in the coal face not only improves the extraction difficulty and reduces the coal yield, but also easily induces geological disasters such as gas outburst or water permeation. Therefore, the accurate detection of the position and the development condition of the hidden thin coal belt in the working face before the stoping is one of the prerequisites for reasonably designing the stoping plan and preventing and reducing the disaster. The existing underground thin coal belt detection mainly adopts a drilling method, and has low efficiency and low precision. The underground geophysical prospecting method lacks a method capable of accurately detecting a thin coal belt, only a channel wave detection technology utilizes the frequency dispersion characteristic of channel waves to detect the thickness of coal at present, but the difference between actual underground data and the frequency dispersion characteristic of theoretical channel waves is large, and the detection result of the method is not ideal.
Disclosure of Invention
The invention provides a data acquisition and processing method, which realizes the detection of the position of a hidden thin coal belt in a coal bed by utilizing the periodic change of the amplitude of a refraction wave transmitted on a coal-rock interface. In order to solve the technical problems, the invention adopts the following technical scheme:
a thin coal band detection method based on refraction wave period amplitude attenuation comprises the following steps:
and (S1) arranging instruments: laying a seismic survey line, wherein the seismic survey line consists of S excitation points and R receiving points; seismic data d with the total channel number of N is formed between the excitation point and the receiving point through signal acquisition and data transmissioni(t), wherein t is time; i is seismic channel number, i belongs to [1, N ]]，N＝S×R；
S2, acquiring formation data and refracted wave period T: obtaining longitudinal wave velocity v of surrounding rockrAnd coal bed longitudinal wave velocity vcMeasuring the thickness h of the coal seam exposed by the roadway at the side wall of the roadway, and calculating the period T of the refracted wave;
s3 obtaining the periodic amplitude coefficient a of the refracted wavep：
For seismic data di(t) obtaining seismic channels s after inverse convolution and intra-channel equalizationi(t); dividing an imaging area corresponding to the coal face into grids, wherein each grid corresponds to an imaging point P (x, y); calculating the distance between the imaging point P (x, y) and the connecting line of each shot point and the demodulator probe, and selecting the distance to be less than a preset threshold value LWSeismic trace s corresponding to the connecting line ofi(t) forming a gather ΦP(ii) a Opposite gather phiPInner seismic channels si(t) calculating refraction wave order n corresponding to P (x, y) pointpSeismic trace si(t) and reference track s0(t) in refractive order npThe amplitude ratio of (a) is taken as the refraction wave period amplitude coefficient a of the P (x, y) pointp。
Optionally, the instrument layout specifically includes: arranging earthquake survey lines in a transportation lane and/or a return airway of the coal face, wherein the earthquake survey lines consist of S blast holes arranged at intervals and R wave detection holes arranged at intervals; the explosive is buried in the blast hole to serve as an excitation point, and the detector is buried in the detection hole to serve as a receiving point; seismic data d with the total channel number of N is formed between the excitation point and the receiving point through signal acquisition and data transmissioni(t), wherein t is time; i is seismic channel number, i belongs to [1, N ]]，N＝S×R。
Optionally, said reference track s0The acquisition method of (t) includes:
setting a time window parameter tWIntercept from ti-tWTo ti+tWSeismic data over a period of time di(t) forming seismic wavelets w (t); using seismic wavelet w (t) to seismic data di(t) carrying out the reactionConvolution is carried out to obtain seismic data d 'after deconvolution'i(t); taking T as a parameter, and using an automatic gain control algorithm to process seismic data d'i(t) performing intra-channel equalization to obtain seismic channel si(t); counting each data in si(kT+ti) Sum of upper amplitudes AiSelecting the track with the largest amplitude sum as the reference track s0(t)；
Optionally, S3 obtains the refraction wave period amplitude coefficient apThe method specifically comprises the following steps:
according to the position of the excitation point (x)S,yS) Receiving point position (x)R,yR) And the velocity v of the longitudinal wave of the surrounding rockrCalculating the first arrival time t of the refracted wave of each seismic channeli；
Dividing an imaging area of a coal face into grids, and setting the number of the units to be X in the direction of the trend and Y in the direction of the trend; imaging points P (X, Y) corresponding to each grid, wherein X belongs to [1, X ], Y belongs to [1, Y ];
Calculating all imaging points in the imaging area according to the formula to obtain the imaging result of the refraction wave period amplitude coefficient of the area, wherein the abnormal area in the imaging result corresponds to the boundary of the thin coal belt, and M is a trace set phiPTotal number of tracks.
Optionally, the equalized seismic traces siThe acquisition method of (t) includes:
setting a time window parameter tWIn seismic data di(t) intercepting slave ti-tWTo ti+tWData in the time period is taken as seismic wavelets w (t);
using seismic wavelet w (t) to seismic data di(t) deconvoluting the frequency domain seismic signal D 'from the equation'i(ω), further converting D 'by inverse Fourier transform'i(ω) transformation to time domain to obtain deconvoluted seismic data d'i(t)；
Where ω is frequency, Di(ω) is di(t) in the frequency domain, W (ω) is the frequency domain of W (t), the frequency domain is obtained by Fourier transform, W*(omega) is the conjugate complex number of W (omega), and gamma takes a value of 0.1-0.01;
d 'is subjected to gain control algorithm by taking refracted wave period T as parameter'i(t) performing intra-channel equalization, the equalized seismic signal si(t)；
A thin coal belt detection system based on refraction wave period amplitude attenuation is provided with:
an instrument layout module: laying a seismic survey line, wherein the seismic survey line consists of S excitation points and R receiving points; seismic data d with the total channel number of N is formed between the excitation point and the receiving point through signal acquisition and data transmissioni(t), where i is the seismic trace number, i ∈ [1, N)]T is time; n ═ sxr;
the module for acquiring the formation data and the refracted wave period T comprises: obtaining longitudinal wave velocity v of surrounding rockrAnd coal bed longitudinal wave velocity vcMeasuring the thickness h of the coal seam exposed by the roadway at the side wall of the roadway, and calculating the period T of the refracted wave;
obtaining the periodic amplitude coefficient a of the refracted wavepA module: for seismic data di(t) obtaining seismic channels s after inverse convolution and intra-channel equalizationi(t); dividing an imaging area corresponding to the coal face into grids, wherein each grid corresponds to an imaging point P (x, y); calculating the distance between the imaging point P (x, y) and the connecting line of each shot point and the demodulator probe, and selecting the distance to be less than a preset threshold value LWSeismic trace s corresponding to the connecting line ofi(t) forming a gather ΦP(ii) a Opposite gather phiPInner seismic channels si(t) calculating refraction wave order n corresponding to P (x, y) pointpSeismic trace si(t) and reference track s0(t) in refractive order npThe amplitude ratio of (a) is taken as the refraction wave period amplitude coefficient a of the P (x, y) pointp。
Optionally, the instrument layout specifically includes: arranging earthquake survey lines in a transportation lane and/or a return airway of the coal face, wherein the earthquake survey lines consist of S blast holes arranged at intervals and R wave detection holes arranged at intervals; the explosive is buried in the blast hole to serve as an excitation point, and the detector is buried in the detection hole to serve as a receiving point; seismic data d with the total channel number of N is formed between the excitation point and the receiving point through signal acquisition and data transmissioni(t), wherein t is time; i is seismic channel number, i belongs to [1, N ]]，N＝S×R。
Optionally, said reference track s0The acquisition method of (t) includes:
setting a time window parameter tWIntercept from ti-tWTo ti+tWSeismic data over a period of time di(t) forming seismic wavelets w (t); using seismic wavelet w (t) to seismic data di(t) deconvoluting to obtain deconvoluted seismic data d'i(t); taking T as a parameter, and using an automatic gain control algorithm to process seismic data d'i(t) performing intra-channel equalization to obtain seismic channel si(t); counting each data in si(kT+ti) Sum of upper amplitudes AiSelecting the track with the largest amplitude sum as the reference track s0(t)；
Optionally, obtaining the periodic amplitude coefficient a of the refracted wavepThe module specifically includes:
according to the position of the excitation point (x)S,yS) Receiving point position (x)R,yR) And the velocity v of the longitudinal wave of the surrounding rockrCalculating the first arrival time t of the refracted wave of each seismic channeli；
Dividing an imaging area of a coal face into grids, and setting the number of the units to be X in the direction of the trend and Y in the direction of the trend; imaging points P (X, Y) corresponding to each grid, wherein X belongs to [1, X ], Y belongs to [1, Y ];
Calculating all imaging points in the imaging area according to the formula to obtain the imaging result of the refraction wave period amplitude coefficient of the area, wherein the abnormal area in the imaging result corresponds to the boundary of the thin coal belt, and M is a trace set phiPTotal number of tracks.
Optionally, the method further comprises the step of equalized seismic traces si(t) an acquisition module:
setting a time window parameter tWIn seismic data di(t) intercepting slave ti-tWTo ti+tWData in the time period is taken as seismic wavelets w (t);
using seismic wavelet w (t) to seismic data di(t) deconvolution, i.e. frequency domain is obtained from the following equationSeismic signal D'i(ω), further converting D 'by inverse Fourier transform'i(ω) transformation to time domain to obtain deconvoluted seismic data d'i(t)；
Where ω is frequency, Di(ω) is di(t) in the frequency domain, W (ω) is the frequency domain of W (t), the frequency domain is obtained by Fourier transform, W*(omega) is the conjugate complex number of W (omega), and gamma takes a value of 0.1-0.01;
d 'is subjected to gain control algorithm by taking refracted wave period T as parameter'i(t) performing intra-channel equalization, the equalized seismic signal si(t)；
Compared with the prior art, the invention has the following beneficial technical effects:
the arrangement mode of the underground observation system required by the invention is similar to that of the channel wave detection project, the equipment can be shared, and the underground construction and the transmission channel wave detection project can be completed simultaneously without increasing extra workload and construction cost. The coal bed refraction wave used by the invention is another underground seismic wave generated simultaneously with the trough wave, and the generation and propagation mechanism of the underground seismic wave is different from that of the trough wave, so that the thin coal band boundary imaging result in the working surface generated by the invention is not influenced by the quality of the trough wave, is favorable for supplementing and referring to the trough wave imaging result, is favorable for more accurately explaining the thin coal band boundary, and improves the coal mine recovery working efficiency and the resource utilization rate.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:
FIG. 1 is a diagram showing the relationship between refracted waves and coal beds;
FIG. 2 is a cross-sectional view of the relationship of blast holes, wave detection holes and coal seams and roadways;
FIG. 3 is a plan view of the relationship of blast holes, wave detection holes and coal seams and roadways; in FIG. 3, the straight connecting line between the blast hole and the wave detecting hole is the "connecting line" mentioned in the present invention;
FIG. 4 is a schematic view of a model of a working surface containing a thin coal strip, a being a plan view and b being a cross-sectional view;
FIG. 5 is a three-dimensional elastic wave forward modeling result of the working surface model;
FIG. 6 is a truncated wavelet;
FIG. 7 shows refracted wave signals of R81, R92 and R150;
FIG. 8 shows the results of deconvolution and channel equalization of the R81, R92, and R150 refracted wave signals;
FIG. 9 shows the results of periodic amplitude coefficient imaging of the working surface refracted wave.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, 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.
Seismic data di(t) refers to the seismic signals collected by the geophones over a period of time after seismic source excitation.
The seismic channel means that after a seismic source is excited by a shot point, a seismic wave signal acquired by a detector of a certain wave detection point for a period of time is a seismic channel; and (4) sequentially exciting multiple points, and collecting a plurality of seismic channels formed by a plurality of wave detection points to form seismic data.
The term "seismic trace corresponding to a connecting line" refers to a seismic trace formed by connecting a shot point and a demodulator probe, exciting at the shot point, and collecting seismic signals at the demodulator probe.
The downhole seismic data not only include channel waves, but also include refracted waves propagating along the interface between the coal seam and the top and bottom floor strata. The refracted wave of the coal-rock interface has strong periodicity, and the periodicity of the refracted wave is related to the thickness of the coal bed. The reason for this phenomenon is that seismic waves are incident and reflected at the same angle on the coal seam and two interfaces of the top plate and the bottom plate, and each incident generates a refracted wave. Therefore, the received refraction wave has periodicity, and the amplitude of the refraction wave is enhanced after the same time difference. When thin coal zones exist in the coal seam, the condition that seismic waves entering the thin zones are refracted is changed, and the periodic strong amplitude is weakened or disappears. As shown in fig. 1(a), the refracted wave under the condition of constant coal thickness has a strong amplitude every time a fixed time period passes. When a thin coal seam exists in the coal seam, as shown in fig. 1(b) to (c), the strong amplitude at different periods is weakened or disappeared (the arrow in the figure indicates the point where the thin coal seam appears) as the distance between the boundary of the thin coal seam and the origin point is different. Therefore, according to the principle, whether the thin coal belt exists can be determined by comparing the variation of the periodic amplitude of the refracted wave on different seismic channels, and the position of the boundary of the thin coal belt is calculated by determining the period number of the strong amplitude.
The invention discloses a refraction wave period amplitude attenuation-based thin coal belt detection method, which adopts the following data acquisition modes:
and (S1) arranging instruments: simultaneously laying seismic survey lines in a transportation lane and/or a return air lane of a coal face, wherein the survey lines comprise S blast holes arranged at intervals and R wave detection holes arranged at intervals; specifically, blast holes and wave detection holes are drilled in the coal seam which is as close to an interface between the coal seam and a top plate (or the coal seam and a bottom plate as possible and is selected to be closest to a roadway according to the distance between the coal seam and the roadway, the depth of each blast hole is about 2m, and the depth of each wave detection hole is about 1-1.5 m; the spacing between the channels (wave detection holes) is 10-20 m, and the spacing between the guns is 10-20 m. The arrangement mode of the blast holes and the wave detection holes can be that the blast holes and the wave detection holes are distributed at intervals in the same transport lane or return air lane, and the blast holes and the wave detection holes are distributed at intervals in the other transport lane or return air lane, during experiment, the blast holes in the same lane are used as excitation points, and the wave detection points in the other lane are used as receiving points, and then the blast holes and the wave detection holes can be used in an exchange mode; or only blast holes or only wave detection holes are distributed at intervals in the same transportation lane or air return lane, only wave detection holes or only blast holes are distributed at intervals in the other transportation lane or air return lane in the same way, and the experimental principle is the same; such as the arrangements of fig. 2 and 3.
The explosive is buried in the blast hole and is excited in a roadway, the geophone is buried in the demodulation hole and is used for receiving seismic wave signals, and the seismometer receives seismic waves. The relationship between blast holes and detecting holes and coal seams and roadways is shown in figure 2. Sequentially exciting the explosive in each blast hole, receiving all the detectors when blasting each time, and forming seismic data d with the total number of N between the excitation point and the receiving point through signal acquisition and data transmissioni(t), where t is time in milliseconds; i is seismic channel number, i belongs to [1, N ]]N ═ sxr; one-time signal acquisition and data transmission between each excitation point and each receiving point form a seismic channel, and N seismic channels form seismic data di(t) where the signal is transmitted as seismic waves, such as coal bed refracted waves used in the present invention are another downhole seismic waves generated simultaneously with the trough waves.
S2, acquiring formation data and refracted wave period T: obtaining longitudinal wave velocity v of surrounding rockrAnd coal bed longitudinal wave velocity vcMeasuring the thickness h of the coal seam exposed by the roadway at the side wall of the roadway, and calculating the period T of the refracted wave;
s3 obtaining the periodic amplitude coefficient a of the refracted wavep：
To di(t) processing to obtain seismic data s after deconvolution and intra-track equalizationi(t); dividing an imaging area corresponding to the coal face into grids, wherein each grid corresponds to an imaging point P (x, y); calculating the distance between the imaging point P (x, y) and each excitation point and demodulator probe connecting line, and selecting all connecting line distances smaller than a preset threshold value LWSeismic data s corresponding to the links ofi(t) forming a gather ΦP(ii) a Opposite gather phiPInner data of each track si(t) calculating refraction wave order n corresponding to P (x, y) pointpThe seismic channel si(t) and reference track s0(t) at npAmplitude ratio of order as refractive wave period amplitude coefficient a of P (x, y) pointp。
In the embodiments of the present disclosure, the reference track s0The acquisition method of (t) includes:
setting a time window parameter tWIntercept from ti-tWTo ti+tWSeismic data over a period of time di(t) forming seismic wavelets w (t); using w (t) as wavelet to seismic data di(t) deconvoluting to obtain deconvoluted seismic data d'i(t); d 'is subjected to Automatic Gain Control (AGC) algorithm by taking T as parameter'i(t) performing in-channel equalization to obtain si(t); counting each data in si(kT+ti) Sum of upper amplitudes AiSelecting the track with the largest amplitude sum as the reference track s0(t)；
In the embodiment of the present disclosure, S3 obtains the refracted wave period amplitude coefficient apThe method specifically comprises the following steps:
according to the position of the excitation point (x)S,ys) Receiving point position (x)R,yR) And the velocity v of the longitudinal wave of the surrounding rockrCalculating the first arrival time t of the refracted wave of each seismic channeli；
Dividing an imaging area of a coal face into grids, and setting the number of the units to be X in the direction of the trend and Y in the direction of the trend; imaging point P (X, y) corresponding to each grid, X ∈ [1, X ]]，y∈[1，Y](ii) a M is channel set phiPM is a positive integer;
apThe numerical value of the numerical value reflects the thickness of the coal seam at the P point, all imaging points in the imaging area are calculated according to the formula, the imaging result of the refraction wave period amplitude coefficient of the area can be obtained, and the abnormal area in the imaging result corresponds to the boundary of the thin coal belt.
The invention is described in detail below with reference to specific embodiments and the accompanying drawings.
The data processing method mainly comprises the following steps:
1. obtaining longitudinal wave velocity v of surrounding rock from ultrasonic logging data or by ultrasonic measurement of rock samplerAnd the longitudinal wave velocity v of the coal seamc(ii) a And measuring the thickness h of the coal seam exposed by the side wall in two roadways of the target working surface. According to the longitudinal wave velocity v of the surrounding rockrLongitudinal wave velocity v of coal bedcAnd calculating the refraction wave period T according to the coal seam thickness h.
2. Preprocessing actual underground seismic data such as time delay correction and denoising, and then solving first-arrival time t of each refracted longitudinal wavei. Excitation point position (x)S,yS) Receiving point position (x)R,yR) And the velocity v of the longitudinal wave of the surrounding rockrFirst arrival time t of refracted longitudinal waveiComprises the following steps:
3. setting a time window parameter tWAt seismic channel di(t) intercepting slave ti-tWTo ti+tWData in time period as wavelets w (t), where tWGenerally, the time is selected to be 100-200 ms, and can be adjusted according to the actual waveform.
4. With w (t) as a childDeconvoluting the seismic data with waves, i.e. obtaining the frequency domain seismic signal D 'from the following equation'i(ω), further converting D 'by inverse Fourier transform'i(ω) transforming to the time domain to obtain a deconvoluted seismic signal d'i(t)；
Where ω is frequency, Di(ω) is di(t) in the frequency domain, W (ω) is the frequency domain of W (t), the frequency domain is obtained by Fourier transform, W*And (omega) is a complex conjugate of W (omega), gamma is a normal number, and the value of gamma is generally 0.1-0.01 and can be adjusted according to the noise level of original data.
5. D 'is subjected to gain control (AGC) algorithm by taking the refracted wave period T as a parameter'i(t) performing intra-channel equalization, and equalized seismic channels si(t)。
6. Counting each data in si(kT+ti) Sum of upper amplitudes AiSelecting the track with the largest amplitude sum as the reference track s0(t)。
K is a positive integer, and the value of K is less than 10;
7. the imaging area of the coal face is divided into grids, the number of the units is X along the trend direction, and Y along the inclination direction. Let x be 1 and y be 1, and process the imaging points P (x, y) corresponding to each grid one by one.
8. Selecting all seismic channels s connecting lines passing through point P (x, y) from the main channel seti(t) forming a new common image point gather ΦPThe concrete measures are as follows:
(1) let i equal to 1, phiPIs an empty set;
(2) extracting the ith seismic channel s from the main channel seti(t) and from the head of the trackObtaining the position (x) of the ith excitation pointS,yS) And the position of the receiving point (x)R,yR)；
(3) Calculating the distance L between the connecting line of the ith channel from the shot point to the demodulator probe and P (x, y)i：
When L isi<LWWhen the i-th track s is startedi(t) addition of phiPIn which L isWIs a preset threshold value which is generally 5-10 m;
(4) let i be i +1 until i be N, N being the total number of tracks, and repeat the process from step (2).
9. Calculating the periodic amplitude coefficient a (x, y) of the refracted wave at the point P, and adopting the following specific measures:
(1) let i equal 1, a (x, y) equal 0;
(2) acquiring the position (x) of a corresponding excitation point of the ith track from the track headS,yS) Calculating refraction wave order n corresponding to P (x, y) pointp：
Wherein
Represents rounding down;
(3) calculating the ith channel signal si(t) and reference track s0(t) at the n-thpAmplitude ratio a of the order refracted wavei：
(4) Let i be 1, i is defined as,
until i is M, where M is gather ΦPTotal number of tracks from step 9And (2) repeating the treatment.
Let X be X +1 until X be X, and the process is repeated from step 9.
Let Y be Y +1 until Y be Y, and the process is repeated from step 9.
And obtaining the refraction wave period amplitude coefficient imaging results a (x, y) of all the imaging areas, wherein the abnormal areas in the imaging results correspond to the boundaries of the thin coal zones in the coal face.
The effect of the invention is illustrated below by taking a theoretical model and actual data as examples:
the first embodiment is as follows:
the model consists of three layers, namely a top plate, a coal bed and a bottom plate, and the lithology of the top plate is the same as that of the bottom plate. The longitudinal wave velocity of the surrounding rock is 4000m/s, the transverse wave velocity of the surrounding rock is 2300m/s, and the density is 2.56g/cm3(ii) a The longitudinal wave speed of the coal bed is 2000m/s, the transverse wave speed of the coal bed is 1050m/s, and the density is 1.4g/cm3. The normal coal seam thickness is 20m, wherein a thin coal zone exists, and the thickness of the coal seam at the thin coal zone is 12 m. The model is schematically shown in FIG. 4, wherein (a) is a model plan view, and (b) is a model sectional view. The model is forward modeled by a three-dimensional elastic wave forward modeling technique, the seismic source is 400Hz Rake wavelets, and 78 shot simulation results are generated, wherein the 20 th shot is shown in figure 5. The model data is now processed according to the steps of the invention.
And (5) executing the step 2, wherein the thickness h of the coal seam exposed by the side wall is 20 m.
And step 3 is executed, and the period T of the refracted wave is calculated to be 17.3 ms.
Step 4 is executed to calculate the first arrival time t of each refracted longitudinal waveiTaking the R150 channel in the 20 th shot as an example, the excitation point position (400,55) and the receiving point position (690,247) are obtained from the channel head, and the first arrival time t of the refracted longitudinal wave is calculatediIs 93 ms.
Performing step 5, tWSet to 2ms, take the R150 trace as an example, and intercept the signal from 91ms to 95ms as wavelet w (t), as shown in FIG. 6.
Step 6 and step 7 are performed to perform deconvolution and equalization processing on each channel, taking channel R81, channel R92, and channel R150 as examples respectively, the original signal is as shown in fig. 7, and the processed signal is as shown in fig. 8.
Step 8 is executed, after the amplitude sum of each channel is counted, the channel R81 is selected as the reference channel s0(t)。
Step 9 is executed to divide the working plane into 80 × 40 grids, each grid having a size of 10 × 5 m.
Step 11 is executed to calculate the periodic amplitude coefficient of the refracted wave at each point, taking the point (550,100) on the boundary of the thin coal belt as an example, R150 passes through the point, the position of the excitation point in the track head is (400,55), and n can be calculatedpThen, a is calculated from 4i10.15; taking a point (250,100) on the normal coal seam as an example, R92 passes through the point, the excitation point position in the track head is (400,55), and n can be calculatedpThen, a is calculated from 4i3.45. The difference is shown in the dashed box in FIG. 8, where the 4 th order of R92 differs little from the reference trace R81 and the 4 th order of R150 differs much from the reference trace R81, so that points on the thin coal seam boundary have a larger refractive wave period amplitude coefficient than points on normal coal seams.
The imaging result of the refraction wave period amplitude coefficient of the working surface of the model is obtained in step 14, as shown in fig. 9, and is substantially consistent with the position of the thin coal zone in the model.
In general, the method can realize the boundary detection of the thin coal belt by performing refraction wave periodic amplitude coefficient imaging on a working surface by utilizing the periodicity of refraction waves in the coal bed and the characteristic of amplitude attenuation when the coal thickness changes on the premise of knowing the velocity of longitudinal waves of the surrounding rock and the coal bed.
The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.
It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.
In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.
Claims (10)
1. A method for detecting a thin coal band based on refraction wave period amplitude attenuation is characterized by comprising the following steps:
and (S1) arranging instruments: laying a seismic survey line, wherein the seismic survey line consists of S excitation points and R receiving points; seismic data d with the total channel number of N is formed between the excitation point and the receiving point through signal acquisition and data transmissioni(t), wherein t is time; i is seismic channel number, i belongs to [1, N ]]，N＝S×R；
S2, acquiring formation data and refracted wave period T: obtaining longitudinal wave velocity v of surrounding rockrAnd coal bed longitudinal wave velocity vcMeasuring the thickness h of the coal seam exposed by the roadway at the side wall of the roadway, and calculating the period T of the refracted wave;
s3 obtaining the periodic amplitude coefficient a of the refracted wavep：
For seismic data di(t) obtaining seismic channels s after inverse convolution and intra-channel equalizationi(t); dividing an imaging area corresponding to the coal face into grids, wherein each grid corresponds to an imaging point P (x, y); calculating the distance between the imaging point P (x, y) and the connecting line of each shot point and the demodulator probe, and selecting the distance to be less than a preset threshold value LWSeismic trace s corresponding to the connecting line ofi(t) forming a gather ΦP(ii) a Opposite gather phiPInner seismic channels si(t) calculating refraction wave order n corresponding to P (x, y) pointpSeismic trace si(t) and reference track s0(t) in refractive order npThe amplitude ratio of (a) is taken as the period of the refracted wave at the P (x, y) pointCoefficient of amplitude ap。
2. The refractive wave period amplitude attenuation-based thin coal belt detection method according to claim 1, wherein the instrument layout specifically comprises: arranging earthquake survey lines in a transportation lane and/or a return airway of the coal face, wherein the earthquake survey lines consist of S blast holes arranged at intervals and R wave detection holes arranged at intervals; the explosive is buried in the blast hole to serve as an excitation point, and the detector is buried in the detection hole to serve as a receiving point; seismic data d with the total channel number of N is formed between the excitation point and the receiving point through signal acquisition and data transmissioni(t), wherein t is time; i is seismic channel number, i belongs to [1, N ]]，N＝S×R。
3. The refractive wave periodic amplitude attenuation-based thin coal band detection method according to claim 1 or 2, characterized in that the reference channel s0The acquisition method of (t) includes:
setting a time window parameter tWIntercept from ti-tWTo ti+tWSeismic data over a period of time di(t) forming seismic wavelets w (t); using seismic wavelet w (t) to seismic data di(t) deconvoluting to obtain deconvoluted seismic data d'i(t); taking T as a parameter, and using an automatic gain control algorithm to process seismic data d'i(t) performing intra-channel equalization to obtain seismic channel si(t); counting each data in si(kT+ti) Sum of upper amplitudes AiSelecting the track with the largest amplitude sum as the reference track s0(t)；
4. The refractive wave periodic amplitude attenuation-based thin coal belt detection method according to claim 1 or 2, wherein S3 obtains a refractive wave periodic amplitude coefficient apThe method specifically comprises the following steps:
according to the position of the excitation point (x)S，yS) Receiving point position (x)R，yR) And the velocity v of the longitudinal wave of the surrounding rockrCalculating the first arrival time t of the refracted wave of each seismic channeli；
Dividing an imaging area of a coal face into grids, and setting the number of the units to be X in the direction of the trend and Y in the direction of the trend; imaging points P (X, Y) corresponding to each grid, wherein X belongs to [1, X ], Y belongs to [1, Y ];
Calculating all imaging points in the imaging area according to the formula to obtain the imaging result of the refraction wave period amplitude coefficient of the area, wherein the abnormal area in the imaging result corresponds to the boundary of the thin coal belt, and M is a trace set phiPTotal number of tracks.
5. The refractive wave period amplitude attenuation-based thin coal band detection method according to claim 1 or 2, characterized in that the equalized seismic traces siThe acquisition method of (t) includes:
setting a time window parameter tWIn seismic data di(t) intercepting slave ti-tWTo ti+tWData in the time period is taken as seismic wavelets w (t);
using seismic wavelet w (t) to seismic data di(t) deconvoluting the frequency domain seismic signal D 'from the equation'i(ω), further converting D 'by inverse Fourier transform'i(ω) transformation to time domain to obtain deconvoluted seismic data d'i(t)；
Where ω is frequency, Di(ω) is di(t) in the frequency domain, W (ω) is the frequency domain of W (t), the frequency domain is obtained by Fourier transform, W*(omega) is the conjugate complex number of W (omega), and gamma takes a value of 0.1-0.01;
d 'is subjected to gain control algorithm by taking refracted wave period T as parameter'i(t) performing intra-channel equalization, the equalized seismic signal si(t)；
6. A thin coal belt detection system based on refraction wave period amplitude attenuation is characterized in that:
an instrument layout module: laying a seismic survey line, wherein the seismic survey line consists of S excitation points and R receiving points; seismic data d with the total channel number of N is formed between the excitation point and the receiving point through signal acquisition and data transmissioni(t), where i is the seismic trace number, i ∈ [1, N)]T is time; n ═ sxr;
the module for acquiring the formation data and the refracted wave period T comprises: obtaining longitudinal wave velocity v of surrounding rockrAnd coal bed longitudinal wave velocity vcMeasuring the thickness h of the coal seam exposed by the roadway at the side wall of the roadway, and calculating the period T of the refracted wave;
obtaining the periodic amplitude coefficient a of the refracted wavepA module: for seismic data di(t) obtaining seismic channels s after inverse convolution and intra-channel equalizationi(t); dividing an imaging area corresponding to the coal face into grids, wherein each grid corresponds to an imaging point P (x, y); calculating an imaging point P: (x, y) and the distance between each shot point and the connecting line of the demodulator probe, wherein the selected distance is less than a preset threshold value LWSeismic trace s corresponding to the connecting line ofi(t) forming a gather ΦP(ii) a Opposite gather phiPInner seismic channels si(t) calculating refraction wave order n corresponding to P (x, y) pointpSeismic trace si(t) and reference track s0(t) in refractive order npThe amplitude ratio of (a) is taken as the refraction wave period amplitude coefficient a of the P (x, y) pointp。
7. The refractive wave period amplitude attenuation-based thin coal belt detection system according to claim 6, wherein the instrumentation specifically comprises: arranging earthquake survey lines in a transportation lane and/or a return airway of the coal face, wherein the earthquake survey lines consist of S blast holes arranged at intervals and R wave detection holes arranged at intervals; the explosive is buried in the blast hole to serve as an excitation point, and the detector is buried in the detection hole to serve as a receiving point; seismic data d with the total channel number of N is formed between the excitation point and the receiving point through signal acquisition and data transmissioni(t), wherein t is time; i is seismic channel number, i belongs to [1, N ]]，N＝S×R。
8. The refraction wave period amplitude attenuation-based thin coal belt detection system according to claim 6 or 7, wherein the reference trace s0(t) is obtained by the method comprising the following steps:
setting a time window parameter tWIntercept from ti-tWTo ti+tWSeismic data over a period of time di(t) forming seismic wavelets w (t); using seismic wavelet w (t) to seismic data di(t) deconvoluting to obtain deconvoluted seismic data d'i(t); taking T as a parameter, and using an automatic gain control algorithm to process seismic data d'i(t) performing intra-channel equalization to obtain seismic channel si(t); counting each data in si(kT+ti) Sum of upper amplitudes AiSelecting the track with the largest amplitude sum as the reference track s0(t)；
9. The refraction wave periodic amplitude attenuation-based thin coal belt detection system according to claim 6 or 7, characterized in that a refraction wave periodic amplitude coefficient a is obtainedpThe module specifically includes:
according to the position of the excitation point (x)S，yS) Receiving point position (x)R，yR) And the velocity v of the longitudinal wave of the surrounding rockrCalculating the first arrival time t of the refracted wave of each seismic channeli；
Dividing an imaging area of a coal face into grids, and setting the number of the units to be X in the direction of the trend and Y in the direction of the trend; imaging points P (X, Y) corresponding to each grid, wherein X belongs to [1, X ], Y belongs to [1, Y ];
Calculating all imaging points in the imaging area according to the formula to obtain the imaging result of the refraction wave period amplitude coefficient of the area, wherein the abnormal area in the imaging result corresponds to the boundary of the thin coal belt, and M is a trace set phiPTotal number of tracks.
10. The refraction wave period amplitude attenuation-based thin coal belt detection system according to claim 6 or 7, characterized by further comprising equalized seismic traces si(t) an acquisition module:
setting a time window parameter tWIn seismic data di(t) Middle intercept from ti-tWTo ti+tWData in the time period is taken as seismic wavelets w (t);
using seismic wavelet w (t) to seismic data di(t) deconvoluting the frequency domain seismic signal D 'from the equation'i(ω), further converting D 'by inverse Fourier transform'i(ω) transformation to time domain to obtain deconvoluted seismic data d'i(t)；
Where ω is frequency, Di(ω) is di(t) in the frequency domain, W (ω) is the frequency domain of W (t), the frequency domain is obtained by Fourier transform, W*(omega) is the conjugate complex number of W (omega), and gamma takes a value of 0.1-0.01;
d 'is subjected to gain control algorithm by taking refracted wave period factory as parameter'i(t) performing intra-channel equalization, the equalized seismic signal si(t)；
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| CN115932945A (en) * | 2022-10-14 | 2023-04-07 | 扎赉诺尔煤业有限责任公司 | Multi-wave multi-component detection method for residual coal thickness earthquake of excavation roadway |
| CN116774291A (en) * | 2023-08-17 | 2023-09-19 | 四川川交路桥有限责任公司 | Tunnel quality detection method, device, system and storage medium |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115932945A (en) * | 2022-10-14 | 2023-04-07 | 扎赉诺尔煤业有限责任公司 | Multi-wave multi-component detection method for residual coal thickness earthquake of excavation roadway |
| CN115932945B (en) * | 2022-10-14 | 2024-04-02 | 扎赉诺尔煤业有限责任公司 | Method for detecting multi-wave and multi-component of residual coal thickness earthquake in tunneling roadway |
| CN116774291A (en) * | 2023-08-17 | 2023-09-19 | 四川川交路桥有限责任公司 | Tunnel quality detection method, device, system and storage medium |
| CN116774291B (en) * | 2023-08-17 | 2024-03-19 | 四川川交路桥有限责任公司 | Tunnel quality detection method, device, system and storage medium |
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