A method and system for enhancing a gun array first arrival signal

Abstract

The application discloses a kind of methods for enhancing shot gather first arrival signal, first read shot gather data, then calculate each data channel of the same shot gather and do FFT transformation, obtain the first FFT transformation result, then calculate the modulus of the first FFT transformation result, and the value of modulus value sequence is accumulated point by point, obtain the modulus value after accumulation, subsequently calculate mean value and form template, then calculate the angle of modulus value, then use template to replace modulus value, then calculate the second FFT transformation result;The application realizes the function of enhancing shot gather first arrival signal, and the enhancement of first arrival signal can improve the longitude and accuracy of first arrival time detection, because of the similarity of its spectrum, so the most similar template spectrum can be obtained by using the method of multiple data superposition and averaging, so the strength of first arrival signal is adjusted directly by using frequency domain adjustment method, so that the signal-to-noise ratio is adjusted, at the same time, the first arrival time is not changed, which is beneficial to the detection of shot gather first arrival signal, and is suitable for being widely promoted and used.

Description

Technical Field

[0001] This invention relates to the field of first arrival signal processing technology for gun emplacements, and specifically to a method and system for enhancing first arrival signals of gun emplacements. Background Technology

[0002] In petroleum geophysical exploration, a single shot point generates an excitation signal, several acquisition nodes receive the signal, and finally, the received signals are used to create a shot gather file for each shot, based on geographical location. First Arrival Time (FAT) refers to the time when seismic waves first reach the seismic detector from a subsurface reflecting or refracting layer. This time point is crucial for constructing images of subsurface structures and interpreting formation properties. In seismic exploration, seismic waves are generated by the source, travel through strata, and are reflected or refracted at different interfaces. The signals received by the detectors contain information about the velocity and density of the subsurface medium.

[0003] Currently, during field data collection, the strength of the first arrival signal varies due to underground structures and distance from the seismic source, which significantly affects the detection of the first arrival time. Therefore, it is necessary to design a method and system for enhancing the first arrival signal of the shot gather. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and system for enhancing the first arrival signal of a shot gather in order to better and more effectively solve the problem. This method and system enhance the first arrival signal of the shot gather, and the enhancement of the first arrival signal can improve the detection longitude and accuracy of the first arrival time. Due to the similarity of their spectra, the most similar template spectrum can be obtained by averaging multiple data. In this way, the intensity of the first arrival signal can be directly adjusted by the frequency domain adjustment method, thereby adjusting the signal-to-noise ratio while ensuring that the first arrival time does not change, which is beneficial to the detection of the first arrival signal of the shot gather.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for enhancing the first arrival signal of a shot gather includes the following steps:

[0007] Step A: Read the data collected by the shot collection, and then calculate the S of each data track in the same shot collection. i Then perform an FFT transformation to obtain the first FFT transformation result F. i ;

[0008] Step B: Calculate the first FFT transform result F. i The modulus P i And accumulate the modulus P point by point. i The values ​​of the sequence are used to obtain the accumulated modulus P. a ;

[0009] Step C: Calculate the mean and form a template P m ;

[0010] Step D, calculate the modulus P i Angle A i ;

[0011] Step E, using template P m Replace the modulus P i Then calculate the second FFT transformation result F. i ′;

[0012] Step F, using the result F of the second FFT transformation i Perform an inverse fast Fourier transform (IFFT) and generate the inverse transform sequence S. i ′;

[0013] Step G, repeat step C, until all data in the shot gather has been transformed, completing the shot gather initial arrival signal enhancement operation.

[0014] In the aforementioned method for enhancing the first arrival signal of a shot collection, step A involves reading the acquired data from the shot collection and then calculating the S signal for each data channel of the same shot collection. i Then perform an FFT transformation to obtain the first FFT transformation result F. i The specific steps are as follows:

[0015] Step A1, calculate S for each data channel of the same shot set. i If there are M data channels in the channel set, then each data channel S i As shown in formula (1),

[0016] S i =S(t)=[x0,x1,x2…x k , ..., x N-1 ] i (1)

[0017] Where S(t) represents the i-th data point in the shot set, x k Let N be the vibration value at time k, and N be the total length of the vibration values.

[0018] Step A2: Perform an FFT transformation on the i-th data S(t) in the shot set to obtain the first FFT transformation result F. i As shown in formulas (2) and (3),

[0019]

[0020] F i =F(ω)=[c0,c1,c2,…c k , ...c L-1 ] i (3)

[0021] Among them, c k It is the result of the transformation, c k It is a complex number and c k =a k +i*b k a and b are real numbers, L is the total length, and i is the imaginary unit.

[0022] In the aforementioned method for enhancing the first arrival signal of a shot gather, step B involves calculating the first FFT transform result F. i The modulus P i And accumulate the modulus P point by point. i The values ​​of the sequence are used to obtain the accumulated modulus P. a The specific steps are as follows:

[0023] Step B1, calculate the first FFT transform result F i The modulus P i As shown in formula (4),

[0024] P i =|F i |=|F(ω)|=[|c0|, |c1|, |c2|,…|c k |,…,|c L-1 |]i(4)

[0025] Step B2: Calculate the modulus for each point, as shown in formula (5).

[0026]

[0027] Step B3, accumulate the modulus value P point by point. i The values ​​of the sequence are shown in formula (6).

[0028] P a =[y0+|c0|, y1+|c1|, y2+|c2|,…y k +|c k |,…,y L-1 +|c L-1 |](6);

[0029] Step B4: Calculate the accumulated modulus P. a Specifically, it involves calculating the modulus P of all M channels. i As shown in formula (7),

[0030]

[0031] In the aforementioned method for enhancing the first arrival signal of a shot gather, step C involves calculating the mean and forming a template P. m As shown in formula (8),

[0032] Pm =P a / M

[0033] =[y0 / M, y1 / M, y2 / M,…,y k / M,…,y L-1 / M]

[0034] = [z0, z1, z2, ... z k , ...z L-1 (8).

[0035] In the aforementioned method for enhancing the first arrival signal of a shot gather, step D involves calculating the modulus P. i Angle A i The specific steps are as follows:

[0036] Step D1, Angle A i The calculation formula is shown in formula (9).

[0037] A i =Angle(F i )

[0038] =Angle(F(ω))

[0039] =[Angle(c0),Angle(c1),Angle(c2),…,Angle(c k ), ..., Angle(c L-1 )] i

[0040] =[α0,α1,α2,…,α k , …, α L-1 ] i (9);

[0041] Step D2: Calculate the angle for each point. Since the result of the Fourier transform is a negative number c... k =a k +i*b k ,and Then according to a k and b k The sign of the symbol is located for the value of -π to π, as shown in formula (10).

[0042] If a k >0 and b k If the result is greater than 0, then the result is (0, π / 2).

[0043] If a k <0 and b k If the value is greater than 0, then the result is (π / 2, π).

[0044] If a k >0 and bk If <0, then the result is (-π / 2, 0).

[0045] If a k <0 and b k If <0, the result is (-π, -π / 2)(10).

[0046] In the aforementioned method for enhancing the first arrival signal of a shot gather, step E involves using template P. m Replace the modulus P i Then calculate the second FFT transformation result F. i As shown in formula (11),

[0047] a k ′=z k *cos(α k ), b k ′=z K *sin(α k ), c k ′=a k ′+i*b k ′,

[0048] F i ′=F(ω)′=[c0′,c1′,c2′,…c k ′,…c L-1 ′] i (11).

[0049] In the aforementioned method for enhancing the first arrival signal of a shot gather, step F involves using the second FFT transform result F... i Perform an inverse fast Fourier transform (IFFT) and generate the inverse transform sequence S. i As shown in formula (12),

[0050]

[0051] A shot gather first-arrival signal enhancement system includes a data reading module, a modulus calculation module, a mean calculation module, an angle calculation module, a template replacement module, an inverse transformation module, and a loop module. The data reading module is used to read the shot gather acquisition data and then calculate the S-value for each data channel of the same shot gather. i Then perform an FFT transformation to obtain the first FFT transformation result F. i The modulus calculation module is used to calculate the first FFT transformation result F. i The modulus P i And accumulate the modulus P point by point. i The values ​​of the sequence are used to obtain the accumulated modulus P. a The mean calculation module is used to calculate the mean and form a template P. m The angle calculation module is used to calculate the modulus P.i Angle A i The template replacement module is used to replace template P. m Replace the modulus P i Then calculate the second FFT transformation result F. i The inverse transform module is used to utilize the second FFT transform result F i Perform an inverse fast Fourier transform (IFFT) and generate the inverse transform sequence S. i The loop module is used to repeat the mean calculation module until all data in the shot gather has been transformed, thus completing the initial arrival signal enhancement operation of the shot gather.

[0052] The beneficial effects of this invention are: The method and system for enhancing the first arrival signal of a shot gather, as described in this invention, first reads the acquired data from the shot gather, and then calculates the S-value of each data channel within the same shot gather. i Then perform an FFT transformation to obtain the first FFT transformation result F. i Next, calculate the first FFT transformation result F. i The modulus P i And accumulate the modulus P point by point i The values ​​of the sequence are used to obtain the accumulated modulus P. a Then the mean is calculated and a template P is formed. m Then calculate the modulus P. i Angle A i Then use template P m Replace the modulus P i Then calculate the second FFT transformation result F. i Then, the second FFT transformation result F is used. i Perform an inverse fast Fourier transform (IFFT) and generate the inverse transform sequence S. i Finally, the mean is calculated repeatedly until all data in the shot gather has been transformed, thus completing the first arrival signal enhancement operation. This effectively realizes the function of enhancing the first arrival signal of the shot gather. The enhancement of the first arrival signal can improve the longitude and accuracy of the first arrival time detection. Since it is the same shot gather, the data generated by excitation can be used as the signal, and the differences and noise caused by the reflection or refraction layer can be regarded as noise. Due to the similarity of their spectra, the most similar template spectrum can be obtained by averaging multiple data. In this way, the intensity of the first arrival signal can be directly adjusted by the frequency domain adjustment method, thereby adjusting the signal-to-noise ratio and ensuring that the first arrival time does not change, which is beneficial to the detection of the first arrival signal of the shot gather. Attached Figure Description

[0053] Figure 1 This is a flowchart of a method and system for enhancing the first arrival signal of a gun group according to the present invention. Detailed Implementation

[0054] The present invention will now be further described with reference to the accompanying drawings.

[0055] like Figure 1 As shown, the present invention provides a method and system for enhancing the first arrival signal of a gun gathering, comprising the following steps:

[0056] Step A: Read the data collected by the shot collection, and then calculate the S of each data track in the same shot collection. i Then perform an FFT transformation to obtain the first FFT transformation result F. i The specific steps are as follows:

[0057] Step A1, calculate S for each data channel of the same shot set. i If there are M data channels in the channel set, then each data channel S i As shown in formula (1),

[0058] S i =S(t)=[x0,x1,x2…x k , ..., x N-1 ] i (1)

[0059] Where S(t) represents the i-th data point in the shot set, x k Let N be the vibration value at time k, and N be the total length of the vibration values.

[0060] Step A2: Perform an FFT transformation on the i-th data S(t) in the shot set to obtain the first FFT transformation result F. i As shown in formulas (2) and (3),

[0061]

[0062] F i =F(ω)=[c0,c1,c2,…c k , ...c L-1 ] i (3)

[0063] Among them, c k It is the result of the transformation, c k It is a complex number and c k =a k +i*b k a and b are real numbers, L is the total length, and i is the imaginary unit.

[0064] Step B: Calculate the first FFT transform result F. i The modulus P i And accumulate the modulus P point by point. i The values ​​of the sequence are used to obtain the accumulated modulus P. a The specific steps are as follows:

[0065] Step B1, calculate the first FFT transform result F i The modulus P i As shown in formula (4),

[0066] P i =|F i |=|F(ω)|=[|c0|, |c1|, |c2|,…|c k |,…,|c L-1 |]i(4)

[0067] Step B2: Calculate the modulus for each point, as shown in formula (5).

[0068]

[0069] Step B3, accumulate the modulus value P point by point. i The values ​​of the sequence are shown in formula (6).

[0070] P a =[y0+|c0|, y1+|c1|, y2+|c2|,…y k +|c k |,…,y L-1 +|c L-1 |](6);

[0071] Step B4: Calculate the accumulated modulus P. a Specifically, it involves calculating the modulus P of all M channels. i As shown in formula (7),

[0072]

[0073] Step C: Calculate the mean and form a template P m As shown in formula (8),

[0074] P m =P a / M

[0075] =[y0 / M, y1 / M, y2 / M,…,y k / M,…,y L-1 / M]

[0076] = [z0, z1, z2, ... z k , ...z L-1 (8).

[0077] Step D, calculate the modulus P i Angle A i The specific steps are as follows:

[0078] Step D1, Angle A i The calculation formula is shown in formula (9).

[0079] A i =Angle(F i )

[0080] =Angle(F(ω))

[0081] =[Angle(c0),Angle(c1),Angle(c2),…,Angle(c k ), ..., Angle(c L-1 )] i

[0082] =[α0,α1,α2,…,α k , …, α L-1 ] i (9);

[0083] Step D2: Calculate the angle for each point. Since the result of the Fourier transform is a negative number c... k =a k +i*b k ,and Then according to a k and b k The sign of the symbol is located for the value of -π to π, as shown in formula (10).

[0084] If a k >0 and b k If the result is greater than 0, then the result is (0, π / 2).

[0085] If a k <0 and b k If the value is greater than 0, then the result is (π / 2, π).

[0086] If a k >0 and b k If <0, then the result is (-π / 2, 0).

[0087] If a k <0 and b k If <0, the result is (-π, -π / 2)(10).

[0088] Step E, using template P m Replace the modulus P i Then calculate the second FFT transformation result F. i As shown in formula (11),

[0089] a k ′=z k *cos(α k ), b k′=z K *sin(α k ), c k ′=a k ′+i*b k ′,

[0090] F i ′=F(ω)′=[c0′,c1′,c2′,…c k ′,…c L-1 ′] i (11).

[0091] Step F, using the result F of the second FFT transformation i Perform an inverse fast Fourier transform (IFFT) and generate the inverse transform sequence S. i As shown in formula (12),

[0092]

[0093] Step G, repeat step C, until all data in the shot gather has been transformed, completing the shot gather initial arrival signal enhancement operation.

[0094] A shot gather first-arrival signal enhancement system includes a data reading module, a modulus calculation module, a mean calculation module, an angle calculation module, a template replacement module, an inverse transformation module, and a loop module. The data reading module is used to read the shot gather acquisition data and then calculate the S-value for each data channel of the same shot gather. i Then perform an FFT transformation to obtain the first FFT transformation result F. i The modulus calculation module is used to calculate the first FFT transformation result F. i The modulus P i And accumulate the modulus P point by point. i The values ​​of the sequence are used to obtain the accumulated modulus P. a The mean calculation module is used to calculate the mean and form a template P. m The angle calculation module is used to calculate the modulus P. i Angle A i The template replacement module is used to replace template P. m Replace the modulus P i Then calculate the second FFT transformation result F. i The inverse transform module is used to utilize the second FFT transform result F i Perform an inverse fast Fourier transform (IFFT) and generate the inverse transform sequence S. i The loop module is used to repeat the mean calculation module until all data in the shot gather has been transformed, thus completing the initial arrival signal enhancement operation of the shot gather.

[0095] In summary, the first-arrival signal enhancement method and system of the present invention first reads the acquired data from the shot collection, and then calculates the S signal for each data channel of the same shot collection. i Then perform an FFT transformation to obtain the first FFT transformation result F. i Next, calculate the first FFT transformation result F. i The modulus P i And accumulate the modulus P point by point i The values ​​of the sequence are used to obtain the accumulated modulus P. a Then the mean is calculated and a template P is formed. m Then calculate the modulus P. i Angle A i Then use template P m Replace the modulus P i Then calculate the second FFT transformation result F. i Then, the second FFT transformation result F is used. i Perform an inverse fast Fourier transform (IFFT) and generate the inverse transform sequence S. i Finally, the mean is calculated repeatedly until all data in the shot gather has been transformed, thus completing the shot gather first arrival signal enhancement operation. This invention effectively realizes that the system has the function of enhancing the shot gather first arrival signal, and the enhancement of the first arrival signal can improve the longitude and accuracy of the first arrival time detection. At the same time, since it is the same shot gather, the data generated by excitation can be used as the signal, and the difference and noise caused by the reflection or refraction layer can be regarded as noise. Due to the similarity of their spectra, the most similar template spectrum can be obtained by averaging multiple data. In this way, the intensity of the first arrival signal is directly adjusted by the frequency domain adjustment method, thereby adjusting the signal-to-noise ratio, while ensuring that the first arrival time does not change, which is beneficial to the detection of the shot gather first arrival signal.

[0096] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for enhancing the first arrival signal of a shot gather, characterized in that: Includes the following steps, Step A: Read the data collected by the shot collection, and then calculate the S of each data track in the same shot collection. i Then perform an FFT transformation to obtain the first FFT transformation result F. i ; Step B: Calculate the first FFT transform result F. i The modulus P i And accumulate the modulus P point by point. i The values ​​of the sequence are used to obtain the accumulated modulus P. a The specific steps are as follows: Step B1, calculate the first FFT transform result F i The modulus P i As shown in formula (4), P i =|F i |=|F(ω)|=[|c0|,|c1|,|c2|,…|c k |,…,|c L-1 |] i (4) Where L is the total length; Step B2: Calculate the modulus for each point, as shown in formula (5). Step B3, accumulate the modulus value P point by point. i The values ​​of the sequence are shown in formula (6). P a =[y0+|c0|,y1+|c1|,y2+|c2|,…y k +|c k |,…,y L-1 +|c L-1 |](6); Step B4: Calculate the accumulated modulus P. a Specifically, it involves calculating the modulus P of all M channels. i As shown in formula (7), Step C: Calculate the mean and form a template P m As shown in formula (8), P m =P a / M =[y0 / M,y1 / M,y2 / M,…,y k / M,…,y L-1 / M] =[z0,z1,z2,…z k ,…With L-1 ](8); Step D, calculate the modulus P i Angle A i The specific steps are as follows: Step D1, Angle A i The calculation formula is shown in formula (9). A i =Angle(F i ) =Angle(F(ω)) =[Angle(c0),Angle(c1),Angle(c2),…,Angle(c k ),…,Angle(c L-1 )] i ＝[α0，α1，α2，…，α k ，…，α L-1 ] i (9)； Step D2: Calculate the angle for each point. Since the result of the Fourier transform is a complex number c... k =a k +j*b k ,and Then according to a k and b k The sign of the symbol is located for the value of -π to π, as shown in formula (10). If a k >0 and b k If the result is greater than 0, then the result is (0, π / 2). If a k <0 and b k If the value is greater than 0, then the result is (π / 2, π). If a k >0 and b k If <0, then the result is (-π / 2, 0). If a k <0 and b k If <0, the result is (-π, -π / 2)(10); Step E, using template P m Replace the modulus P i Then calculate the second FFT transformation result F. i As shown in formula (11), a k ′=z k *cos(a k ),b k ′=z k *sin(a k ),c k ′=a k ′+j*b k ′, F i ′=F(ω)′=[c0′,c1′,c2′,…c k ′,…c L-1 ′] i (11); Step F, using the result F of the second FFT transformation i Perform an inverse fast Fourier transform (IFFT) and generate the inverse transform sequence S. i ′; Step G, repeat step C, until all data in the shot gather has been transformed, completing the shot gather initial arrival signal enhancement operation.

2. The method for enhancing the first arrival signal of a shot gathering according to claim 1, characterized in that: Step A: Read the data collected by the shot collection, and then calculate the S of each data track in the same shot collection. i Then perform an FFT transformation to obtain the first FFT transformation result F. i The specific steps are as follows: Step A1, calculate S for each data channel of the same shot set. i If there are M data channels in the gun set, then each data channel has S... i As shown in formula (1), S i =S(t)=[x0,x1,x2...x n ,...,x N-1 ] i (1) Where S(t) represents the i-th data point in the shot set, x n Let N be the vibration value at time n, and N be the total length of the vibration value. Step A2: Perform an FFT transformation on the i-th data S(t) in the shot set to obtain the first FFT transformation result F. i As shown in formulas (2) and (3), F i =F(ω)=[c0,c1,c2,…c k ,…c L-1 ] i (3) Among them, c k It is the result of the transformation, c k It is a complex number and c k =a k +j*b k a k and b k All are real numbers, L is the total length, and j is the imaginary unit.

3. The method for enhancing the first arrival signal of a shot gathering according to claim 2, characterized in that: Step F, using the result F of the second FFT transformation i Perform an inverse fast Fourier transform (IFFT) and generate the inverse transform sequence S. i As shown in formula (12), 4. A first-arrival signal enhancement system for a shot gather, wherein the enhancement process of the shot gather first-arrival signal enhancement system is based on the shot gather first-arrival signal enhancement method according to any one of claims 1-3, characterized in that: The system includes a data reading module, a modulus calculation module, a mean calculation module, an angle calculation module, a template replacement module, an inverse transformation module, and a loop module. The data reading module is used to read the data acquired by the shot collection and then calculate the S value for each data trace of the same shot collection. i Then perform an FFT transformation to obtain the first FFT transformation result F. i ; The modulus calculation module is used to calculate the first FFT transformation result F. i The modulus P i And accumulate the modulus P point by point. i The values ​​of the sequence are used to obtain the accumulated modulus P. a ; The mean calculation module is used to calculate the mean and form a template P. m ; The angle calculation module is used to calculate the modulus P. i Angle A i ; The template replacement module is used to replace template P. m Replace the modulus P i Then calculate the second FFT transformation result F. i ′; The inverse transform module is used to utilize the second FFT transform result F i Perform an inverse fast Fourier transform (IFFT) and generate the inverse transform sequence S. i ′; The loop module is used to repeat the mean calculation module until all channel data in the shot gather has been transformed, thus completing the initial arrival signal enhancement operation of the shot gather.

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