A method for pulse conversion of excavation seismic data based on traveling wave separation

Abstract

The present invention relates to a data pulsing method, which belongs to the field of geological exploration technology, and specifically to a method for pulsing seismic data during excavation based on traveling wave separation. Compared with existing pulsing technologies, the present invention can effectively suppress the wave fields generated by interference sources, especially interference sources in the opposite direction from the survey line, such as sound waves, conveyor belts, and other moving vehicles. This can significantly improve the signal-to-noise ratio of effective waves, such as direct waves excited by the tunnel boring machine's seismic source and reflected waves from the front, thereby improving imaging reliability, enhancing the accuracy of advanced detection, and improving the accuracy of disaster prediction and forecasting.

Description

Technical Field

[0001] The present invention relates to a data pulse method, belongs to the field of geological exploration technology, and specifically relates to a method for pulse-forming seismic data while drilling based on traveling wave separation. Background Art

[0002] Tunneling seismic detection is a cutting-edge technology used to proactively detect hidden geological anomalies ahead of the tunneling face during underground coal mine excavation. Based on the concept of passive seismic analysis, this technology uses the tunneling machine as the signal excitation source. Seismic interferometry is used to pulse data to extract effective reflections from the geological anomalies ahead. Reflection wave imaging is then used to determine the location and size of the geological anomalies ahead of the tunneling face. However, due to the numerous interference sources in the mine environment, such as acoustic waves, conveyor belts, and transport vehicles, the wave fields generated by these interference sources can affect the quality of the pulsed recordings of tunneling seismic data, reducing the signal-to-noise ratio (SNR). This, in turn, affects the accuracy of proactive detection, leading to false alarms and missed alarms, seriously threatening the lives and property of mine personnel. Previously, random noise attenuation methods were often used to improve the quality of tunneling seismic signals, but this method was unable to suppress the coherent seismic wave fields generated by interference sources.

[0003] Based on this, it is very necessary to propose a method for improving the quality of pulsed recording of while-drilling seismic data, which is of great significance to improving the accuracy of advance detection of while-drilling seismic data and ensuring safe and efficient production in coal mine tunneling. Summary of the Invention

[0004] The following is a brief summary of one or more aspects to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceivable aspects and is neither intended to identify key or critical elements of all aspects nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that will be provided later.

[0005] The main purpose of the present invention is to solve the technical problems existing in the prior art and provide a method for pulsing seismic data while drilling based on traveling wave separation.

[0006] To solve the above problems, the solution of the present invention is:

[0007] A method for pulse conversion of excavation seismic data based on traveling wave separation, comprising:

[0008] According to the transmission direction of the signal in the mine tunnel, it is divided into forward waves and backward waves. The forward wave refers to the seismic wave traveling in the tunnel toward the head-on direction, while the backward wave refers to the seismic wave traveling in the tunnel in the opposite direction.

[0009] Arrange the seismic signals collected by the receiving points (equidistantly distributed) according to the distance from the receiving point to the head (in this example, they are arranged in ascending order, i.e. the first signal is closest to the head);

[0010] Perform Hilbert transform on the arranged multi-channel seismic data (denoted as F) to obtain the complex domain wave field Ht;

[0011] Perform Hilbert transform on the complex domain wave field Ht along the spatial axis to obtain the wave field HxHt;

[0012] Calculate the receding wave field Sb = F – HxHt and the forward wave field Sf = F + HxHt;

[0013] Perform inverse Hilbert transform on the wave field Sb along the time axis to obtain the wave field

[0014] Back to the wave field As a reference signal, it performs multi-channel seismic interference with itself to obtain the pulsed wave field G;

[0015] Inverse Hilbert transform back to the time domain;

[0016] Bandpass filtering removes random noise.

[0017] Therefore, compared with the existing technology, the advantages of the present invention are: it can effectively suppress the wave field generated by the interference source, especially the interference source from the survey line to the opposite direction of the head-on, such as sound waves, belt conveyors and other moving vehicles, and can greatly improve the signal-to-noise ratio of effective waves such as the direct wave excited by the tunnel boring machine source and the reflected wave from the front head, thereby improving the imaging reliability, and enhancing the accuracy of advanced detection and disaster prediction and forecasting. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments of the present invention and, together with the description, further serve to explain the principles of the invention and to enable one skilled in the art to make and use the disclosure.

[0019] Figure 1 The diagram illustrates the survey line arrangement and wave field propagation path in the embodiment of the present invention;

[0020] Figure 2 The data processing flow chart in the embodiment of the present invention is illustrated.

[0021] Embodiments of the present invention will be described with reference to the accompanying drawings. DETAILED DESCRIPTION

[0022] Example

[0023] The present invention will be described in detail below with reference to specific implementation methods and the accompanying drawings.

[0024] See also Figure 1 、 Figure 2 , the present invention is achieved by the following steps:

[0025] The wave field propagating toward the front of the tunnel is defined as the forward wave, while the seismic wave field propagating in the opposite direction is defined as the backward wave. Therefore, the direct wave generated by the tunnel boring machine and the reflected wave generated by the hidden abnormal geological bodies in front of the tunnel (such as faults, collapse columns and goafs) are both backward waves. These two wave fields are also the effective wave fields required for tunneling seismic detection. The forward wave field is an interference wave and needs to be filtered out.

[0026] The arrangement of survey lines for collecting seismic data during excavation is as follows: Figure 1 As shown, the detectors are arranged at equal intervals from the head-on distance, with the closest detector set as the first channel. The collected data are arranged according to the channel sequence number, and the data is set as F(x,t), where x is the spatial coordinate and t is the time;

[0027] A segment of data F(x, t) is intercepted at a certain time length from the continuous seismic data during excavation.

[0028] In order to eliminate the interference waves in the original excavation seismic data, the original data F(x,t) is separated by traveling waves. First, the original data is Hilbert transformed along the time of each track to obtain the wave field H after Hilbert transformation. t (x, t), which is two-dimensional seismic data in the complex domain:

[0029]

[0030] Then, along the x-axis, H t (x, t) is subjected to spatial Hilbert transform time by time, and the wave field H after the two-dimensional Hilbert transform of space and time is obtained. x H t (x,t), and H t (x, t), this data is two-dimensional seismic data in the complex domain:

[0031]

[0032] Using H x H t (x, t), the forward wave S can be calculated f (x, t) and the receding wave S b (x,t):

[0033]

[0034] Different from the conventional method of using full wave field F(x,t) as reference signal for seismic interferometry, the present invention believes that when the forward wave is used as the reference signal, a large number of interference waves will be generated, while the backward wave contains the direct signal of the tunnel boring machine source required for seismic interferometry, as well as the reflected wave that encounters anomalies when propagating to the front of the tunnel. Based on this, the present invention uses the backward wave S b (x, t) is used as the reference signal of the tunnel boring machine source, and S also contains effective reflection waves. b (x, t) to perform two-dimensional deconvolution interferometry.

[0035] For the receding wave S b (x, t) performs an inverse Hilbert transform along the x-axis, and we get

[0036]

[0037] use Each channel is used as a reference signal to perform seismic deconvolution interference with the signals of other channels to eliminate the influence of continuous vibration of the roadheader and realize signal pulseization:

[0038]

[0039] In the formula, ε is a small enough positive number to ensure the stability of the formula. Its value is related to the level of random noise. The greater the noise, the greater the ε. g |x s Indicated by x s Excite x g Receive; “*” indicates complex conjugate.

[0040] The obtained G(t;x g |x s ) data is complex domain data, which can be transformed back to the real domain by performing an inverse Hilbert transform:

[0041]

[0042] The obtained F(t;x g |x s ) is the pulsed result of the excavation seismic data after traveling wave separation, and its physical meaning is x s Point excitation x g The virtual seismic wave field received at the point. The continuous characteristics of the tunnel boring machine source signal are eliminated during the seismic interferometry process. Furthermore, because traveling wave separation is used to filter out the forward waves in the data before interferometry, the extracted wave field effectively eliminates interference waves from other non-head-on locations, especially those from the roadway entrance, resulting in a better signal-to-noise ratio.

[0043] For F(t;x g |xs ) to perform bandpass filtering (recommended filtering parameters: 5Hz-200Hz) to further filter out random noise:

[0044]

[0045] Where H(t) represents the bandpass filter factor in the time domain, and the symbol “*” represents convolution.

[0046] Output the final pulsed virtual seismic data set F(t; x g |x s ), used for subsequent reflection wave imaging during excavation seismic excavation.

[0047] Return to step 3 and start calculating the data for the next time period.

[0048] From the above description, it can be seen that compared with the existing pulse technology, this embodiment of the present invention can effectively suppress the wave field generated by the interference source, especially the interference source from the survey line to the opposite direction of the head-on, such as sound waves, belt conveyors and other moving vehicles, and can greatly improve the signal-to-noise ratio of effective waves such as the direct wave excited by the tunnel boring machine source and the reflected wave from the front head, thereby improving the imaging reliability, and enhancing the accuracy of advanced detection and disaster prediction and forecasting.

[0049] In this embodiment, although the above methods are illustrated and described as a series of actions for simplicity of explanation, it should be understood and appreciated that these methods are not limited by the order of the actions, because according to one or more embodiments, some actions may occur in a different order and / or concurrently with other actions from the illustrations and descriptions herein or not illustrated and described herein but understandable to those skilled in the art.

[0050] Note that references in the specification to "one embodiment," "an embodiment," "example embodiment," "some embodiments," etc., indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment may include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it would be within the knowledge of those skilled in the art to implement such feature, structure, or characteristic in conjunction with other embodiments, whether or not explicitly described.

[0051] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for pulsing seismic data while drilling based on traveling wave separation, characterized in that: include: Arrange the seismic signals collected by equally distributed receiving points according to the distance between the receiving points and the head-on; Performing Hilbert transform on the arranged multi-channel seismic data F channel by channel to obtain a first wave field; performing Hilbert transform on the first wave field along a spatial axis to obtain a second wave field; Calculating a receding wave field based on the multi-channel seismic data and the second wave field; performing an inverse Hilbert transform on the receding wave field to obtain a third wave field; Multi-channel seismic interference is performed on the third wave field to obtain a pulsed fourth wave field; and an inverse Hilbert transform is performed on the fourth wave field to obtain a pulsed result of the excavation seismic data after traveling wave separation.

2. The method for pulsing seismic data while drilling based on traveling wave separation according to claim 1, characterized in that: include: Arrange the seismic signals collected by the receiving points in ascending order according to the collection positions and the head-on distances of the receiving points.

3. The method for pulsing seismic data while drilling based on traveling wave separation according to claim 1, characterized in that: The Hilbert transform of the arranged multi-channel seismic data is performed channel by channel based on the following formula to obtain the first wave field: Where x is the receiving point position, τ is the seismic signal delay time, t is the seismic signal time, F(x,τ) is the multi-channel seismic data corresponding to time τ, and H t (x, t) is the first wave field.

4. The method for pulsing seismic data while drilling based on traveling wave separation according to claim 1, characterized in that: The first wave field is Hilbert transformed along the spatial axis based on the following formula to obtain the second wave field: Where x is the receiving point position, is the delay distance of the receiving point, and t is the earthquake signal time.

5. The method for pulsing seismic data while drilling based on traveling wave separation according to claim 1, characterized in that: The receding wave field is calculated based on the following formula: S b (x,t)=F(x,t)-H x H t (x,t) Where S b (x, t) is the wave field of the receding wave, F(x, t) is the multi-channel seismic data, H x H t (x, t) is the second wave field.

6. The method for pulsing seismic data while drilling based on traveling wave separation according to claim 1, characterized in that: The third wave field is obtained by performing an inverse Hilbert transform along the x-axis on the second wave field based on the following formula: Where x is the receiving point position, is the delay distance of the receiving point, t is the earthquake signal time, For the retreat wave field.

7. The method for pulsing seismic data while drilling based on traveling wave separation according to claim 1, characterized in that: Using each channel in the third wave field as a reference signal, multi-channel seismic interference is performed with other channel signals based on the following formula to eliminate the influence of continuous vibration of the roadheader and obtain the pulsed fourth wave field: In the formula, ε is a small enough positive number to ensure the stability of the formula. Its value is related to the level of random noise. The greater the noise, the greater the ε. g |x s The earthquake signal is represented by x s Excite x g Receive; "*" indicates complex conjugate, x s is the coordinate of the virtual excitation point, x g is the receiving point coordinate, is x g The receding wave received by the point, is x s The receding wave received by the point, G(t; x g |x s ) is the fourth wave field.

8. The method for pulsing seismic data while drilling based on traveling wave separation according to claim 1, characterized in that: The inverse Hilbert transform of the fourth wave field is performed based on the following formula to obtain the time domain pulse conversion result of the excavation seismic data after traveling wave separation: Where τ is the earthquake signal delay time, t is the earthquake signal time, x s is the coordinate of the virtual excitation point, x g is the coordinate of the receiving point, F(t; x g |x s ) is the time domain pulse of the excavation seismic data.

9. The method for pulsing seismic data while drilling based on traveling wave separation according to claim 1, characterized in that: Band-pass filtering is performed on the pulsed results of the traveling wave separated seismic data.

10. The method for pulsing seismic data while drilling based on traveling wave separation according to claim 9, characterized in that: Bandpass filtering is performed on the pulsed seismic data after traveling wave separation based on the following formula: Where H(t) represents the bandpass filter factor in the time domain, and the symbol "*" represents convolution. represents the fifth wave field obtained after filtering the fourth wave field, where x s represents the virtual excitation point of the seismic signal, x g represents the earthquake signal receiving point, and t represents the earthquake signal time.

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