Shot gather first arrival signal enhancement method and system

Abstract

The invention discloses a shot gather first arrival signal enhancement method, which comprises the following steps of: reading shot gather acquisition data, calculating each data channel of the same shot gather and performing FFT (Fast Fourier Transform) to obtain a first FFT result, calculating a module value of the first FFT result, accumulating values of a module value sequence point by point to obtain an accumulated module value, calculating a mean value and forming a template, and performing first arrival signal enhancement on a shot gather. Calculating the angle of the modulus value, replacing the modulus value with a template, and calculating a second FFT conversion result; according to the method, the function of enhancing the first arrival signal of the shot gather is realized, the detection longitude and accuracy of the first arrival time can be improved by enhancing the first arrival signal, and the most similar template frequency spectrum can be obtained by adopting a multi-data superposition averaging method due to the similarity of the frequency spectrum; therefore, the intensity of the first arrival signal is directly adjusted by adopting a frequency domain adjustment method, so that the signal-to-noise ratio is adjusted, the first arrival time is ensured to be unchanged, the detection of the shot gather first arrival signal is facilitated, and the method is suitable for being widely popularized and used.

Description

Technical Field

[0001] The present invention relates to the technical field of shot gather first-arrival signal processing, and in particular to a shot gather first-arrival signal enhancement method and system. Background Art

[0002] In petroleum geophysical exploration, an excitation shot generates an excitation signal, and several acquisition nodes receive the signal. Finally, the received signal is converted into a shot collection file for each shot according to the geographical location. The first arrival time refers to the time when the seismic wave first arrives at the seismic detector from the underground reflection layer or refraction layer. This time point is crucial for constructing an image of the underground structure and interpreting the properties of the formation. In seismic exploration, seismic waves are excited by the source, pass through the formation and are reflected or refracted at different interfaces. The signal received by the detector contains information about the velocity and density of the underground medium.

[0003] At present, when collecting data in the field, the strength of the first arrival signal will be different due to the underground structure and the distance from the earthquake source, and it will have a great impact on the detection of the first arrival time; therefore, it is necessary to design a method and system for enhancing the first arrival signal of a shot gather. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and to 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. The method and system realize the function of enhancing the first arrival signal of a 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 the spectrum, the most similar template spectrum can be obtained by using the method of multi-data superposition and averaging. In this way, the intensity of the first arrival signal is directly adjusted by using the frequency domain adjustment method, so that the signal-to-noise ratio is adjusted, and at the same time, it is ensured that the first arrival time does not change, which is beneficial to the detection of the first arrival signal of the shot gather.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

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

[0007] Step A: read the shot collection data and then calculate each data channel S of the same shot collection. i And do FFT transformation to obtain the first FFT transformation result F i ;

[0008] Step B, calculate the first FFT transformation result F i The modulus value P i , and accumulate the modulus value P point by point i The value of the sequence, get the accumulated modulus value P a ;

[0009] Step C, calculate the mean and form the template P m ;

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

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

[0012] Step F, using the second FFT transformation result F i ′ Perform inverse fast Fourier transform IFFT and form the inverse transformed sequence S i ′;

[0013] Step G, repeat step C until all the data in the shot gather are transformed, and the shot gather first arrival signal enhancement operation is completed.

[0014] The aforementioned shot gather first arrival signal enhancement method includes step A, reading the shot gather acquisition data, and then calculating each data channel S of the same shot gather. i And do FFT transformation to obtain the first FFT transformation result F i , the specific steps are as follows,

[0015] Step A1: Calculate each data channel S of the same shot gather i , assuming that there are M data channels in the data 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] Among them, S(t) is the i-th data in the shot set, x k is the vibration value at the kth moment, and N is the total length of the vibration value;

[0018] Step A2: Perform 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 formula (2) and formula (3),

[0019]

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

[0021] Among them, c k is the transformed result after transformation, c k 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 shot gather first arrival signal enhancement method, step B is to calculate the first FFT transformation result F i The modulus value P i , and accumulate the modulus value P point by point i The value of the sequence, get the accumulated modulus value P a , the specific steps are as follows,

[0023] Step B1, calculate the first FFT transformation result F i The modulus value 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 value for each point, as shown in formula (5),

[0026]

[0027] Step B3, accumulate the modulus value P point by point i The value of the sequence, as 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, forming the accumulated modulus value P a , specifically, calculate all the module values ​​P of M channels i , as shown in formula (7),

[0030]

[0031] The aforementioned method for enhancing the first arrival signal of a shot gather, step C, 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] The aforementioned method for enhancing the first arrival signal of a shot gather, step D, calculates the modulus value P i Angle A i , the specific steps are as follows,

[0036] Step D1, Angle A i The calculation formula of 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, find the angle of each point, since the result of Fourier transform is a negative number c k =a k +i*b k ,and According to a k and b k The symbol of is located at the value of -π~π, as shown in formula (10),

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

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

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

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

[0046] In the aforementioned shot gather first arrival signal enhancement method, step E, using template P m Replace the modulus value P i , and 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 shot gather first arrival signal enhancement method, step F, using the second FFT transformation result F i ′ Perform inverse fast Fourier transform IFFT and form the inverse transformed 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 circulation module. The data reading module is used to read the shot gather acquisition data and then calculate each data channel S of the same shot gather. i And do FFT transformation to get the first FFT transformation result F i ; The modulus calculation module is used to calculate the first FFT transformation result F i The modulus value P i , and accumulate the modulus value P point by point i The value of the sequence, get the accumulated modulus value 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 module value Pi Angle A i ; The template replacement module is used to use the template P m Replace the modulus value P i , and then calculate the second FFT transformation result F i '; The inverse transform module is used to use the second FFT transform result F i ′ Perform inverse fast Fourier transform IFFT and form the inverse transformed sequence S i '; The loop module is used to repeat the mean value calculation module until all the channel data in the shot gather are transformed, thus completing the shot gather first arrival signal enhancement operation.

[0052] The beneficial effects of the present invention are as follows: a method and system for enhancing the first arrival signal of a shot gather first reads the shot gather acquisition data, and then calculates each data channel S of the same shot gather. i And do FFT transformation to obtain the first FFT transformation result F i , then calculate the first FFT transformation result F i The modulus value P i And accumulate the modulus value P point by point i The value of the sequence, get the accumulated modulus value P a , then calculate the mean and form the template P m , and then calculate the modulus value P i Angle A i , then use the template P m Replace the modulus value P i , and then calculate the second FFT transformation result F i ', then use the second FFT transform result F i ′ Perform inverse fast Fourier transform IFFT and form the inverse transformed sequence S i ′, and finally the mean value is calculated repeatedly until all the data in the shot gather are transformed, and the shot gather first arrival signal enhancement operation is completed, which effectively realizes that the system has the function of enhancing 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. At the same time, since it is the same shot gather, the data generated by the excitation can be used as the signal, and the difference formed by the reflection layer or the refraction layer and the influence of the noise can be considered as noise. Due to the similarity of its spectrum, the method of multi-data superposition and averaging can be used to obtain the most similar template spectrum. In this way, the frequency domain adjustment method is used to directly adjust the intensity of the first arrival signal, so that the signal-to-noise ratio is adjusted, and at the same time, it is ensured that the first arrival time does not change, which is conducive to the detection of the first arrival signal of the shot gather. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 The present invention is a flow chart of a shot gather first arrival signal enhancement method and system. DETAILED DESCRIPTION

[0054] The present invention will be further described below in conjunction with the accompanying drawings.

[0055] like Figure 1 As shown, a method and system for enhancing the first arrival signal of a shot gather of the present invention comprises the following steps:

[0056] Step A: read the shot collection data and then calculate each data channel S of the same shot collection. i And do FFT transformation to obtain the first FFT transformation result F i , the specific steps are as follows,

[0057] Step A1: Calculate each data channel S of the same shot gather i , assuming that there are M data channels in the data 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] Among them, S(t) is the i-th data in the shot set, x k is the vibration value at the kth moment, and N is the total length of the vibration value;

[0060] Step A2: Perform 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 formula (2) and formula (3),

[0061]

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

[0063] Among them, c k is the transformed result after transformation, c k 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 transformation result F i The modulus value P i , and accumulate the modulus value P point by point i The value of the sequence, get the accumulated modulus value P a , the specific steps are as follows,

[0065] Step B1, calculate the first FFT transformation result F i The modulus value 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 value for each point, as shown in formula (5),

[0068]

[0069] Step B3, accumulate the modulus value P point by point i The value of the sequence, as 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, forming the accumulated modulus value P a , specifically, calculate all the module values ​​P of M channels i , as shown in formula (7),

[0072]

[0073] Step C, calculate the mean and form the 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 value P i Angle A i , the specific steps are as follows,

[0078] Step D1, Angle A i The calculation formula of 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, find the angle of each point, since the result of Fourier transform is a negative number c k =a k +i*b k ,and According to a k and b k The symbol of is located at the value of -π~π, as shown in formula (10),

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

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

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

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

[0088] Step E, using template P m Replace the modulus value P i , and 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 second FFT transformation result F i ′ Perform inverse fast Fourier transform IFFT and form the inverse transformed sequence S i ′, as shown in formula (12),

[0092]

[0093] Step G, repeat step C until all the data in the shot gather are transformed, and the shot gather first arrival signal enhancement operation is completed.

[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 circulation module. The data reading module is used to read the shot gather acquisition data and then calculate each data channel S of the same shot gather. i And do 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 value P i , and accumulate the modulus value P point by point i The value of the sequence, get the accumulated modulus value 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 module value P i Angle A i ; The template replacement module is used to use the template P m Replace the modulus value P i , and then calculate the second FFT transformation result F i '; The inverse transform module is used to use the second FFT transform result F i ′ Perform inverse fast Fourier transform IFFT and form the inverse transformed sequence S i '; The loop module is used to repeat the mean value calculation module until all the channel data in the shot gather are transformed, thus completing the shot gather first arrival signal enhancement operation.

[0095] In summary, a method and system for enhancing the first arrival signal of a shot gather of the present invention first reads the shot gather acquisition data, and then calculates each data channel S of the same shot gather. i And do FFT transformation to obtain the first FFT transformation result F i , then calculate the first FFT transformation result F i The modulus value P i And accumulate the modulus value P point by point i The value of the sequence, get the accumulated modulus value P a , then calculate the mean and form the template P m , and then calculate the modulus value P i Angle A i , then use the template P m Replace the modulus value P i , and then calculate the second FFT transformation result F i ', then use the second FFT transform result F i ′ Perform inverse fast Fourier transform IFFT and form the inverse transformed sequence S i ′, and finally the mean value is calculated repeatedly until all the data channels in the shot gather are transformed, and the shot gather first arrival signal enhancement operation is completed; the present invention effectively realizes that the system has the function of enhancing 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. At the same time, because it is the same shot gather, the data generated by the excitation can be used as the signal, and the difference formed by the reflection layer or the refraction layer and the influence of the noise can be regarded as noise. Due to the similarity of the spectrum, the method of multi-data superposition and averaging can be used to obtain the most similar template spectrum. In this way, the frequency domain adjustment method is used to directly adjust the intensity of the first arrival signal so that the signal-to-noise ratio is adjusted, and at the same time, it is ensured that the first arrival time does not change, which is conducive to the detection of the first arrival signal of the shot gather.

[0096] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for enhancing the first arrival signal of a shot gather, characterized in that: The following steps are included: Step A: read the shot collection data and calculate each data channel S of the same shot collection. i And do FFT transformation to get the first FFT transformation result F i ; Step B, calculate the first FFT transformation result F i The modulus value P i , and accumulate the modulus value P point by point i The value of the sequence, get the accumulated modulus value P a ; Step C, calculate the mean and form the template P m ; Step D, calculate the modulus value P i Angle A i ; Step E, using template P m Replace the modulus value P i , and then calculate the second FFT transformation result F i ′; Step F, using the second FFT transformation result F i ′ Perform inverse fast Fourier transform IFFT and form the inverse transformed sequence S i ′; Step G, repeat step C until all the data in the shot gather are transformed, and the shot gather first arrival signal enhancement operation is completed.

2. A shot gather first arrival signal enhancement method according to claim 1, characterized in that: Step A: read the shot collection data and calculate each data channel S of the same shot collection. i And do FFT transformation to get the first FFT transformation result F i , the specific steps are as follows, Step A1: Calculate each data channel S of the same shot gather i , assuming that there are M data channels in the data set, then each data channel S i As shown in formula (1), S i =S(t)=[x0,x1,x2...x k ,...,x N-1 ] i (1) Among them, S(t) is the i-th data in the shot set, x k is the vibration value at the kth moment, and N is the total length of the vibration value; Step A2: Perform 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 formula (2) and formula (3), F i =F(ω)=[c0,c1,c2,…c k ,…c L-1 ] i (3) Among them, c k is the transformed result after transformation, c k 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.

3. A shot gather first arrival signal enhancement method according to claim 2, characterized in that: Step B, calculate the first FFT transformation result F i The modulus value P i , and accumulate the modulus value P point by point i The value of the sequence, get the accumulated modulus value P a , the specific steps are as follows, Step B1, calculate the first FFT transformation result F i The modulus value P i , as shown in formula (4), P i =|F i |=|F(ω)|=[|c0|,|c1|,|c2|,…|c k |,…,|c L-1 |]i(4) Step B2, calculate the modulus value for each point, as shown in formula (5), Step B3, accumulate the modulus value P point by point i The value of the sequence, as 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, forming the accumulated modulus value P a , specifically, calculate all the module values ​​P of M channels i , as shown in formula (7), 4. A shot gather first arrival signal enhancement method according to claim 3, characterized in that: Step C, calculate the mean and form the 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)。 5. A shot gather first arrival signal enhancement method according to claim 4, characterized in that: Step D, calculate the modulus value P i Angle A i , the specific steps are as follows, Step D1, Angle A i The calculation formula of 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, find the angle of each point, since the result of Fourier transform is a negative number c k =a k +i*b k ,and According to a k and b k The symbol of is located at the value of -π~π, as shown in formula (10), If a k >0 and b k >0, then the result is (0, π / 2), If a k <0 and b k >0, then the result is (π / 2, π), If a k >0 and b k <0, the result is (-π / 2, 0), If a k <0 and b k <0, the result is (-π, -π / 2)(10).

6. A shot gather first arrival signal enhancement method according to claim 5, characterized in that: Step E, using template P m Replace the modulus value P i , and 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 ′+i*b k ′, F i ′=F(ω)′=[c0′,c1′,c2′,…c k ′,…c L-1 ′] i (11)。 7. A shot gather first arrival signal enhancement method according to claim 6, characterized in that: Step F, using the second FFT transformation result F i ′ Perform inverse fast Fourier transform IFFT and form the inverse transformed sequence S i ′, as shown in formula (12), 8. A shot gather first arrival signal enhancement system, characterized in that: It includes a data reading module, a modulus calculation module, a mean value calculation module, an angle calculation module, a template replacement module, an inverse transformation module and a circulation module. The data reading module is used to read the shot collection data and then calculate each data channel S of the same shot collection. i And do FFT transformation to get the first FFT transformation result F i ; The modulus calculation module is used to calculate the first FFT transformation result F i The modulus value P i , and accumulate the modulus value P point by point i The value of the sequence, get the accumulated modulus value P a ; The mean value calculation module is used to calculate the mean value 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 use the template P m Replace the modulus value P i , and then calculate the second FFT transformation result F i ′; The inverse transform module is used to use the second FFT transform result F i ′ Perform inverse fast Fourier transform IFFT and form the inverse transformed sequence S i ′; The loop module is used to repeat the mean value calculation module until all the trace data in the shot gather are transformed, thus completing the shot gather first arrival signal enhancement operation.

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