A method and system for measuring the sensitivity of an airgun source hydrophone

Abstract

The application provides a kind of air gun source hydrophone sensitivity measurement method and system, belong to marine seismic exploration field.The air gun source hydrophone sensitivity measurement method obtains hydrophone record by single gun excitation test before offshore exploration construction, then obtains hydrophone sensitivity using hydrophone record.Using the application can obtain the sensitivity of air gun source hydrophone;Through actual test shows that the application can accurately measure the sensitivity of hydrophone, can be used for hydrophone sensitivity correction, improves the quality and reliability of air gun source monitoring.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of marine seismic exploration, and particularly relates to a method and system for measuring sensitivity of a hydrophone of an air gun source. BACKGROUND

[0002] The air gun source is a main source form of marine seismic exploration, and the quality of marine seismic exploration data is directly affected by the air gun source. Therefore, monitoring of the excitation quality of the air gun source is very important.

[0003] In order to suppress sea surface virtual reflection and improve the quality of the source signal, the air gun source is generally used in the form of an array composed of multiple single guns. The monitoring of the excitation signal of the source is monitored by the near-field hydrophone arranged above each air gun. However, due to different models and batches, or different use times, the sensitivities of different hydrophones will change, which means that the response amplitudes of different hydrophones to the same signal are different, which brings uncertainty to the accurate monitoring of the air gun source signal, especially for simulating far-field signals through near-field hydrophone signal recording.

[0004] Currently, the sensitivity of the air gun source hydrophone is generally provided by the standard value during factory testing. This standard value can correct the differences between different models and batches, but it cannot correct the changes in sensitivity caused by the use time of the hydrophone. SUMMARY

[0005] The present application aims to solve the problems in the prior art, and provides a method and system for measuring the sensitivity of the hydrophone of the air gun source, which can obtain the sensitivity of the hydrophone, correct the sensitivity differences caused by all reasons of the hydrophone, and improve the accuracy and reliability of the monitoring of the air gun source signal quality.

[0006] The present application is achieved by the following technical solutions:

[0007] In a first aspect, the present application provides a method for measuring the sensitivity of the hydrophone of the air gun source, which obtains the hydrophone record through the single gun excitation test before marine exploration construction, and then obtains the sensitivity of the hydrophone by using the hydrophone record.

[0008] Further improvements of the present application are as follows:

[0009] The method comprises:

[0010] (1) inputting the hydrophone record of the single gun excitation;

[0011] (2) pre-processing the hydrophone record to obtain a pre-processed record;

[0012] (3) picking up the peak amplitude of hydrophone;

[0013] (4) amplitude compensation for the peak amplitude of hydrophone;

[0014] (5) calculating the sensitivity of hydrophone.

[0015] The further improvement of the present application is that:

[0016] The single-gun excited hydrophone record in step (1) refers to the record of signals received by all hydrophones when only one gun is excited.

[0017] The further improvement of the present application is that:

[0018] The operation of step (2) includes:

[0019] The following processing is performed on each hydrophone record:

[0020] (21) DC removal is performed on the hydrophone record to obtain a DC removed record;

[0021] (22) band-pass filtering is performed on the DC removed record to obtain a preprocessed record.

[0022] The further improvement of the present application is that:

[0023] The operation of step (21) includes:

[0024] The sample average value is obtained by superimposing all sample values of the hydrophone record and dividing by the sample number;

[0025] The DC removed record is obtained by subtracting the sample average value from each sample value of the hydrophone record;

[0026] The further improvement of the present application is that:

[0027] The low cutoff frequency of the band-pass filtering in step (22) is ≤3Hz, and the high cutoff frequency is ≥400Hz;

[0028] The further improvement of the present application is that:

[0029] The operation of step (3) includes:

[0030] The following processing is performed on each hydrophone record:

[0031] (31) picking up the peak amplitude v i，peak of the preprocessed record;

[0032] (32) taking the sample point where the peak amplitude v i，peak is located as the center, selecting 10 sample points before and after it to perform linear interpolation or nonlinear interpolation to obtain an interpolated record;

[0033] (33) Re-harvest the peak amplitude of the interpolated record to obtain the new peak amplitude v′. i,peak .

[0034] A further improvement of the present invention is that:

[0035] In step (32), the sampling interval of the interpolated sample points is less than 0.1ms.

[0036] A further improvement of the present invention is that:

[0037] The operation of step (4) includes:

[0038] Perform the following treatment on each hydrophone:

[0039] (41) Calculate the distance r from the hydrophone to the air gun. i ;

[0040] (42) Utilize the new peak amplitude v′ corresponding to the hydrophone i,peak and r i The compensated amplitude v′ of the hydrophone was calculated. i :v′ i =v′ i，peak ·r i ;

[0041] A further improvement of the present invention is that:

[0042] The operation of step (5) includes:

[0043] Sort all the compensated amplitudes of the hydrophones and find the largest compensated amplitude.

[0044] The compensated amplitude v′ of each hydrophone i The hydrophone sensitivity is obtained by dividing the amplitude by the maximum compensation value.

[0045] A second aspect of the present invention provides a system for measuring the sensitivity of an air gun vibrating source hydrophone, the system comprising:

[0046] The system includes:

[0047] Hydrophone recording and acquisition unit: used to input hydrophone records triggered by a single gun;

[0048] Preprocessing unit: connected to the hydrophone recording and acquisition unit, used to preprocess the hydrophone recordings to obtain preprocessed records;

[0049] Peak pickup unit: connected to the preprocessing unit, used to accurately pick up the peak amplitude of the hydrophone;

[0050] An amplitude compensation unit connected with the peak picking unit, used for amplitude compensation of the peak amplitude of the hydrophone;

[0051] A sensitivity calculation unit connected with the amplitude compensation unit, used for calculating the sensitivity of the hydrophone.

[0052] The third aspect of the present application provides a computer readable storage medium, which stores at least one computer executable program, and the at least one program makes the computer execute the steps in the above-mentioned method for measuring the sensitivity of the air gun source hydrophone when executed by the computer.

[0053] Compared with the prior art, the present application has the following beneficial effects:

[0054] 1. The sensitivity of the air gun source hydrophone can be obtained by using the present application;

[0055] 2. The actual test shows that the present application can accurately measure the sensitivity of the hydrophone, and can be used for hydrophone sensitivity correction, thereby improving the quality and reliability of the air gun source monitoring. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 The figure is a step block diagram of the method of the present application;

[0057] Figure 2 The signal of the record of all 24 hydrophones input by a single gun excitation;

[0058] Figure 3 The record after signal preprocessing of Figure 2 ;

[0059] Figure 4 The high-precision peak of the signal picked up by Figure 3 ;

[0060] Figure 5 The record after amplitude compensation of the record of Figure 4 ;

[0061] Figure 6 The final calculated sensitivity result. DETAILED DESCRIPTION

[0062] The present application will be further described in detail below in combination with the drawings:

[0063] In view of the problem that the hydrophone for monitoring the air gun source signal in marine seismic exploration is inconsistent in sensitivity, causing inaccurate measurement of the near-field and far-field signal amplitudes of the source, the application provides a method for measuring the sensitivity of the hydrophone through the data obtained from the routine single-gun shooting test before marine exploration construction, which can solve the correction problem of the sensitivity of the hydrophone and can be used to correct the recorded amplitude of the hydrophone. The method does not increase the cost of marine exploration construction and is operable. Therefore, the application has innovation and practicality in the quality monitoring of the air gun source shooting.

[0064] The implementation of the method of the application is as follows:

[0065] Example 1

[0066] As shown in Figure 1 , the method of the application comprises:

[0067] (1) input the hydrophone record of single-gun shooting:

[0068] The input hydrophone record of single-gun shooting refers to the signal record received by all hydrophones when only one gun is shot, as shown in Figure 2 .

[0069] (2) obtain the preprocessed record by preprocessing the hydrophone record, specifically comprising:

[0070] (21) select a hydrophone record, and perform DC removal on the hydrophone record to obtain a DC-removed record, specifically as follows:

[0071] stack all sample values of the record and divide the sample values by the sample number to obtain the sample average s a , then subtract s a from each sample value of the record to obtain the DC-removed record;

[0072] (22) perform band-pass filtering on the DC-removed record obtained in (21) to obtain the preprocessed record, and the low-frequency oscillation and high-frequency noise are eliminated through the band-pass filtering. Preferably, the low cutoff frequency of the band-pass filtering is ≤3Hz, and the high cutoff frequency is ≥400Hz;

[0073] (23) repeat the steps (21)-(22) above for all other hydrophone records, and finally obtain the preprocessed record v i of each hydrophone, as shown in Figure 3 .

[0074] (3) accurately pick the peak amplitude of the hydrophone, specifically as follows:

[0075] (31) select the preprocessed record v i of a hydrophone, and pick the peak amplitude vi，peak As shown in Figure 4 .

[0076] (32) Take the sample point v i，peak as the center, select 10 sample points before and after it to do linear interpolation or nonlinear interpolation to get the interpolated record, and the sampling interval of the interpolated sample point is less than 0.1 ms.

[0077] (33) For the interpolated record, pick up the peak amplitude to get a new peak amplitude v′ i,peak As shown in Figure 5 . Since the hydrophone record is discrete sampling in time, the sampling point may not fall on the actual peak time, that is, the actual peak time may be between two sample points. Through interpolation, the amplitude of the actual peak sample point can be restored as much as possible.

[0078] (34) Repeat steps (31) to (33) for the preprocessed records of all other hydrophones to get the new peak amplitude of each hydrophone.

[0079] (4) Amplitude compensation is performed on the peak amplitude of the hydrophone, as follows:

[0080] (41) Calculate the distance r i from one of the hydrophones to the air gun: it can be calculated by the distance formula between two points: (x s ,y s ,z s ) is the air gun position, and (x i ,y i ,z i ) is the hydrophone position.

[0081] (42) Calculate the compensated amplitude v′ i of the hydrophone using the corresponding new peak amplitude v′ i,peak and r i : v′ i = v′ i，peak · r i .

[0082] (43) Repeat steps (41) and (42) for all other hydrophones to get the compensated amplitude of each hydrophone.

[0083] With the increase of distance, the amplitude will attenuate. After the distance compensation in step (4), the amplitude attenuation caused by distance is restored, that is, the distance influence factor on the amplitude is eliminated.

[0084] (5) Calculate the sensitivity of the hydrophone, as shown in Figure 6 .

[0085] The compensated amplitude of each hydrophone is normalized to obtain the hydrophone sensitivity of each hydrophone, that is, the final hydrophone sensitivity of each hydrophone, and the specific method is as follows:

[0086] The compensated amplitudes of all hydrophones are sorted to find the maximum compensated amplitude.

[0087] The compensated amplitude of each hydrophone is divided by the maximum compensated amplitude to obtain the hydrophone sensitivity of the hydrophone.

[0088] Figure 6 The channel number in the above formula corresponds to the hydrophone number.

[0089] The implementation of the above method is as follows:

[0090]

Example two

[0091] The present application provides a kind of marine air gun source sensitivity measurement method. According to the problem that the inconsistency of hydrophone sensitivity causes inaccurate monitoring results in marine air gun source monitoring, the method for measuring air gun sensitivity by the data obtained from routine single-gun shooting test before marine exploration construction is proposed, to correct the sensitivity difference caused by all reasons of hydrophone, and the correction method is as follows:

[0092] After the actual air gun array is excited, the record of each hydrophone is divided by the corresponding hydrophone sensitivity of the hydrophone, and the sensitivity of the hydrophone is corrected.

[0093] The amplitude of the signal excited by the actual air gun source objectively exists, and except for the position factor, it will not cause different recording amplitudes due to different hydrophone sensitivities. The sensitivity difference of the hydrophone itself is a system error between the hydrophones, by measuring the size of this system error and eliminating it, the true amplitude of the signal is essentially restored, so after correcting the hydrophone sensitivity, the restored signal is more accurate and reliable when monitoring the air gun shooting quality using the corrected hydrophone record, thereby improving the accuracy and reliability of the air gun source signal quality monitoring. Moreover, this method will not increase the cost of marine exploration construction, and is operable.

[0094] The present application also provides a kind of air gun source hydrophone sensitivity measurement system, the implementation of the system is as follows:

[0095]

Example three

[0096] The system comprises:

[0097] Hydrophone record acquisition unit: for inputting single-gun shooting hydrophone record:

[0098] a preprocessing unit connected with the hydrophone record acquisition unit, used for preprocessing the hydrophone record to obtain a preprocessed record;

[0099] a peak picking unit connected with the preprocessing unit, used for accurately picking the peak amplitude of the hydrophone;

[0100] an amplitude compensation unit connected with the peak picking unit, used for amplitude compensating the peak amplitude of the hydrophone;

[0101] a sensitivity calculation unit connected with the amplitude compensation unit, used for calculating the sensitivity of the hydrophone.

[0102] Specifically, the hydrophone record acquired by the hydrophone record acquisition unit under single-gun excitation refers to the signal record received by all hydrophones under the excitation of only one gun.

[0103] The preprocessing unit performs the following processing on each hydrophone record:

[0104] (21) DC removal is performed on the hydrophone record to obtain a DC-removed record:

[0105] The sample average value is obtained by superimposing all sample values of the hydrophone record and dividing by the sample number;

[0106] Each sample value of the hydrophone record is subtracted by the sample average value to obtain the DC-removed record;

[0107] (22) Band-pass filtering is performed on the DC-removed record to obtain a preprocessed record, preferably, the low cutoff frequency of the band-pass filtering is ≤3Hz, and the high cutoff frequency is ≥400Hz;

[0108] The peak picking unit performs the following processing on the preprocessed record of each hydrophone:

[0109] (31) The peak amplitude v i，peak in the preprocessed record is picked up;

[0110] (32) The peak amplitude v i，peak is centered, and linear interpolation or nonlinear interpolation is performed on 10 sample points before and after the peak amplitude to obtain an interpolated record; the sample interval of the interpolated sample points is less than 0.1ms.

[0111] (33) The peak amplitude of the interpolated record is picked up again to obtain a new peak amplitude v′ i,peak .

[0112] The amplitude compensation unit performs the following processing on each hydrophone:

[0113] (41) The distance r i from the hydrophone to the excited air gun is calculated;

[0114] (42) Utilize the new peak amplitude v′ corresponding to the hydrophone i,peak and r i The compensated amplitude v′ of the hydrophone was calculated. i :v′ i =v′ i，peak ·r i ;

[0115] The sensitivity calculation unit sorts the compensated amplitudes of all hydrophones, finds the largest compensated amplitude, and sets the compensated amplitude v′ of each hydrophone. i The hydrophone sensitivity is obtained by dividing the amplitude by the maximum compensation value.

[0116] The present invention also provides a computer-readable storage medium storing at least one computer-executable program, which, when executed by the computer, causes the computer to perform the steps in the above-described method for measuring the sensitivity of an air gun vibrating source hydrophone.

[0117] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0118] In the description of this invention, unless otherwise stated, the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0119] Finally, it should be noted that the above technical solution is only one embodiment of the present invention. For those skilled in the art, based on the application methods and principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the methods described in the above specific embodiments of the present invention. Therefore, the methods described above are only preferred and have no limiting significance.

Claims

1. A method of measuring the sensitivity of an airgun source hydrophone, characterized by: The method obtains hydrophone records through single-gun shooting test before offshore exploration construction, and then obtains hydrophone sensitivity by using the hydrophone records; The method comprises: (1) inputting the hydrophone records of single-gun shooting; (2) pre-processing the hydrophone records to obtain pre-processed records; (3) picking up the peak amplitude of the hydrophone; The step (3) operation comprises the following processing on the pre-processed records of each hydrophone: (31) picking the peak amplitude in the pre-processed record ; (32) with peak amplitude The sample point is taken as the center, and 10 sample points before and after are selected to perform linear interpolation or nonlinear interpolation to obtain the interpolated record. The sampling interval of the interpolated sample point is less than 0.1 ms. (33) re-pick the peak amplitude of the interpolated record to get a new peak amplitude ; (4) amplitude compensation on the peak amplitude of the hydrophone; (5) Calculate hydrophone sensitivity, the operation includes: sort the compensated amplitudes of all hydrophones, find the largest compensated amplitude; divide the compensated amplitude of each hydrophone by the largest compensated amplitude to obtain the hydrophone sensitivity of the hydrophone of the hydrophone.

2. The method of measuring the sensitivity of an airgun source hydrophone according to claim 1, wherein: The hydrophone records of single-gun shooting in the step (1) refer to the signal records received by all hydrophones when only one gun is shot.

3. The method of measuring airgun source hydrophone sensitivity of claim 1, wherein: The step (2) operation comprises: The following processing on each hydrophone record: (21) direct current removal processing on the hydrophone record to obtain a direct current removal record; (22) band-pass filtering processing on the direct current removal record to obtain the pre-processed records.

4. The method of measuring the sensitivity of an airgun source hydrophone of claim 3, wherein: The step (21) operation comprises: Stacking all sample values of the hydrophone record and dividing by the sample number to obtain a sample average value; Subtracting the sample average value from each sample value of the hydrophone record to obtain the direct current removal record.

5. The method of measuring the sensitivity of an airgun source hydrophone of claim 3, wherein: The low cut-off frequency of the band-pass filtering in the step (22) is ≤3Hz, and the high cut-off frequency is ≥400Hz.

6. The method of measuring the sensitivity of an airgun source hydrophone of claim 5, wherein: The step (4) operation comprises: The following processing on each hydrophone: (41) calculating the distance of the hydrophone to the firing air gun ; (42) using the new peak amplitude corresponding to the hydrophone and calculating the compensated amplitude of the hydrophone : .

7. A system for measuring the sensitivity of an airgun source hydrophone, implementing the method for measuring the sensitivity of an airgun source hydrophone according to claim 1, characterized in that: The system comprises: A hydrophone record acquisition unit for inputting the hydrophone records of single-gun shooting; A preprocessing unit connected with the hydrophone record acquisition unit, for pre-processing the hydrophone records to obtain pre-processed records; A peak picking unit connected with the preprocessing unit, for accurately picking up the peak amplitude of the hydrophone; An amplitude compensation unit connected with the peak picking unit, for amplitude compensation on the peak amplitude of the hydrophone; A sensitivity calculation unit connected with the amplitude compensation unit, for calculating the hydrophone sensitivity.

8. A computer-readable storage medium, characterized in that: The computer readable storage medium stores at least one computer executable program, and the at least one program is executed by the computer to make the computer execute the steps in the method for measuring the sensitivity of the air gun source hydrophone according to any one of claims 1-6.

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