Beach shallow sea OBC double-detection seismic data on-site rapid merging processing method

Abstract

The invention provides a beach and shallow sea OBC double-detection seismic data on-site rapid merging processing method. The beach and shallow sea OBC double-detection seismic data on-site rapid merging processing method comprises the following steps: step 1, carrying out data purification on OBC double-detection seismic data; step 2, performing energy consistency processing on OBC water detection and land detection seismic data; step 3, separating to obtain a downlink multiple wave field; step 4, calculating a seabed reflection coefficient; step 5, calculating to obtain a relatively pure upgoing wave field; step 6, eliminating gun end ringing interference; and step 7, performing superposition to obtain a primary reflected wave superposition section and a seabed first-order downlink multiple wave superposition section. According to the beach and shallow sea OBC double-detection seismic data field rapid merging processing method, the OBC double-detection seismic data rapid merging processing time efficiency of a field seismic data acquisition field is improved, the quality of a field monitoring profile is improved, and the quality control requirement of beach and shallow sea OBC seismic data acquisition is met.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field exploration and development, and in particular to a method for fast on-site merging and processing of beach and shallow sea OBC double-detection seismic data. Background Art

[0002] The OBC acquisition equipment for shallow seas collects two types of seismic data, water detection (velocity detector) and land detection (piezoelectric detector). By merging and processing the two types of seismic data, and using the difference in the response of velocity detectors and piezoelectric detectors to seismic waves, it can eliminate the notch effect caused by ringing, thereby enhancing the effective signal and eliminating the interference of ringing. Although the OBC dual-detection acquisition equipment has the advantages of suppressing noise and making up for the single-component frequency defect compared to traditional single-component detectors, it is restricted by the field processing method of OBC dual-detection seismic data. At present, the monitoring of most shallow sea seismic projects is limited to the separate processing of water detection and land detection seismic data. Some seismic projects are limited by the low signal-to-noise ratio of land detection data, and even only process water detection seismic data. During the construction process, only water detection data is evaluated, and less or even no attention is paid to land detection data, which fails to give full play to the technical advantages of OBC dual-detection acquisition equipment. There are certain differences in the phase, energy, frequency and other properties of the seismic data of the two types of detectors, namely, water detector and land detector. Simple merging processing cannot achieve the ideal stacking effect. The merging processing must take into account the differences in phase, energy and frequency of the two types of detectors. After consistency processing, combined with the seabed reflection coefficient, the uplink and downlink wave fields can be reasonably separated to achieve the purpose of eliminating the interference of seabed ringing and improving the stacking quality. The current relatively mature dual-detection merging processing technology has the characteristics of many steps, high requirements for processing equipment configuration, large amount of calculation, and long processing time. It can neither meet the requirements of fast merging processing on the construction site, nor adapt to the complex reasons for the energy difference of OBC dual-detection seismic data (the energy difference between water detector and land detector includes not only the fixed system difference of the two types of detectors, but also the energy difference caused by the coupling of detectors and the change of water detector ceramic pieces. The difference varies with the terrain and detector performance).

[0003] In the Chinese patent application with application number: CN201710565184.X, a method and device for merging and processing water and land geophone seismic data are involved. The method includes: performing phase processing on land geophone seismic data; performing amplitude processing on water geophone seismic data and land geophone seismic data after phase processing; performing Fourier transform on water geophone seismic data and land geophone seismic data after amplitude processing respectively; calculating calibration factors according to water geophone seismic data and land geophone seismic data after amplitude processing, and calculating seawater depth and seabed reflection coefficient according to water geophone seismic data and land geophone seismic data after Fourier transform; determining mirror combination factors based on seawater depth; performing mirror combination processing on water geophone seismic data and land geophone seismic data in the target area to obtain water and land geophone merged data. The implementation method provided by the application can improve the accuracy of merging and processing of water and land geophone seismic data.

[0004] In the Chinese patent application with application number: CN201510556940.3, a method and device for merging and processing seismic data of water and land detectors is involved. The method uses the correlation function method to directly calculate the optimal calibration factor and the optimal seabed reflection coefficient, with small calculation amount and fast calculation speed; at the same time, by pre-processing the phase of the land detector seismic data and the amplitude of the water and land detector seismic data, the low-frequency noise is reduced and the amplitude energy interference is reduced, thereby improving the accuracy of seawater depth calculation. This application embodiment uses the weighted common point merging processing method based on the calculated calibration factor, seawater depth and seabed reflection coefficient to quickly and accurately realize the merging and processing of underwater detector seismic data and land detector seismic data, thereby effectively eliminating the interference of multiple waves of seawater ringing in the seismic data and improving the signal-to-noise ratio and resolution of the seismic data.

[0005] In the Chinese patent application with application number: CN202110509061.0, a dual-inspection merging method based on Radon transform for dual-inspection data of submarine cables is involved, including: step 1, pre-processing the water inspection and land inspection data respectively; step 2, point-by-point phase scanning of the water inspection and land inspection data, and applying the phase weighting factor obtained by comparison to the land inspection data; step 3, point-by-point scanning of the water inspection and land inspection Radon domain data to obtain the amplitude factor and seabed reflection coefficient of the dual-inspection data; step 4, wave field separation of the water inspection and land inspection data to obtain upgoing wave field data and downgoing wave field data; step 5, merging and superimposing the water inspection and land inspection data in the upgoing wave field. This dual-inspection merging method based on Radon transform for dual-inspection data of submarine cables has high computational efficiency, replaces the use of empirical parameters in conventional merging processing, and can adaptively obtain relevant factors through data-driven without manual participation, thereby improving the processing effect of dual-inspection merging.

[0006] In the Chinese patent application with application number: CN201310736942.1, a method for inverting calibration factors of water and land geophone seismic data is involved, and the method includes: collecting water geophone seismic data and land geophone seismic data for preprocessing; calculating the weighted sum of the root mean square amplitude ratio, autocorrelation function and cross-correlation function of the water geophone seismic data and the land geophone seismic data; calculating the product of the correlation function and the product of the product of the correlation function according to the weighted sum; calculating the maximum variance modulus equation coefficient according to the product of the correlation function and the product of the product of the correlation function, and calculating the coefficient of the calibration factor characteristic equation based on this; constructing the calibration factor characteristic equation and solving the calibration factor characteristic equation; calculating the maximum variance modulus according to the maximum variance modulus equation coefficient and the calibration factor; determining the optimal calibration factor according to the maximum variance modulus; calculating the reflection coefficient according to the optimal calibration factor; drawing a profile of the optimal calibration factor and the seabed reflection coefficient and storing the optimal calibration factor and the seabed reflection coefficient in the seismic data header.

[0007] The above existing technologies are greatly different from the present invention and fail to solve the technical problem we want to solve. Therefore, we have invented a new on-site rapid merging and processing method for shallow-water OBC double-detection seismic data. Summary of the invention

[0008] The purpose of the present invention is to provide a method for rapidly merging and processing OBC dual-check seismic data in shallow waters, which can improve the time efficiency of rapid merging and processing of OBC dual-check seismic data in field seismic data collection, enhance the quality of field monitoring profiles, and meet the quality control requirements of OBC dual-check seismic data collection in shallow waters.

[0009] The purpose of the present invention can be achieved by the following technical measures: a method for rapidly merging and processing shoal and shallow sea OBC dual-detection seismic data on-site, the method comprising:

[0010] Step 1, purify the OBC double-check seismic data;

[0011] Step 2, perform energy consistency processing on the OBC water inspection and land inspection seismic data;

[0012] Step 3, separating and obtaining the downlink multiple wave field;

[0013] Step 4, calculate the seabed reflection coefficient;

[0014] Step 5, calculate and obtain a relatively pure upgoing wave field;

[0015] Step 6, eliminating the interference of the cannon end sound vibration;

[0016] Step 7, superimpose to obtain the first reflection wave superposition profile and the seabed first-order downgoing multiple wave superposition profile.

[0017] The purpose of the present invention can also be achieved by the following technical measures:

[0018] The method for rapidly merging and processing the shallow-water OBC double-detection seismic data on site also includes, before step 1, inputting the OBC double-detection seismic data and performing phase correction on the land-detection seismic data.

[0019] When performing phase correction on land inspection seismic data, comparison or phase analysis of water inspection and land inspection seismic data from the same shot and channel is used to determine the phase difference between the OBC water inspection and land inspection systems. Based on the analyzed phase difference results, phase correction is performed on the land inspection seismic data to eliminate the impact of the phase difference of the OBC double inspection seismic data on the processing results.

[0020] In step 1, the OBC double-check seismic data is cleaned to eliminate abnormal amplitude interference and the influence of bad tracks.

[0021] The method for rapid on-site merging and processing of shallow-water OBC dual-detection seismic data also includes, after step 1, using an energy statistics method to count the energy of each sampling point of the OBC water detection and land detection seismic data one by one, and the water detection energy H i , Lujian Energy G i and saved in the format corresponding to the earthquake data.

[0022] In step 2, the absolute value of the statistical OBC water detection and land detection energy ratio is obtained and moderately smoothed as the water detection and land detection energy correction proportional factor. Based on the proportional factor, the OBC water detection and land detection seismic data are processed for energy consistency.

[0023] In step 2, obtain the statistical OBC water detection energy H i 、Lujian Energy G i The absolute value of the ratio S i =|H i / G i |, the ratio is also saved in the format corresponding to the seismic data, and the sample points are smoothed according to the fluctuation amplitude of the ratio curve to eliminate the influence of outliers.

[0024] In step 2, the smoothing method is mean smoothing, and its formula is n is the smoothing parameter of seismic data sample points. For example, 5-point smoothing takes the average amplitude of 5 adjacent seismic data sampling points as the output value of the sample point after smoothing. Sample point smoothing mainly eliminates the influence of abnormal amplitude on merging processing. The smoothed ratio is used as the proportional factor for energy correction of water detection and land detection. Based on the proportional factor, the energy of OBC land detection seismic data is corrected to make the energy of land detection seismic data consistent with that of water detection seismic data. The correction method is to multiply the land detection energy by the proportional coefficient, that is, G i =G i *S avg。

[0025] In step 3, the land inspection seismic data is subtracted from the water inspection seismic data to separate the downlink multiple wave field. The OBC water inspection and land inspection will simultaneously receive the primary reflection wave X primary , downward multiple waves are usually considered ghost waves X ghost , Upward Multiple Waves X pegleg ; According to the difference in polarity of water detection and land detection in sensing different types of earthquake wave fields, the water detection component and land detection component at the same location have different wave field responses. The wave field response of the water detection component is:

[0026] X hyd (t) = X primary (t)-X ghost (t)-X pegleg (t),

[0027] The wave field response of the land inspection component is:

[0028] X geo (t) = X primary (t)+X ghost (t)-X pegleg (t),

[0029] According to the OBC dual-detection field response formula, after the energy consistency processing of the OBC water and land detection seismic data, the land detection field is subtracted from the water detection field to separate the downlink multiple wave field. Since the sea surface reflection coefficient is large enough, it can be considered that the wave field is consistent with the energy of the primary reflection wave, with only the time difference caused by the sea depth.

[0030] In step 4, after the OBC water and land seismic data are processed for energy consistency, the seabed reflection coefficient is calculated based on the energy errors of the downlink multiple waves separated by different methods; the land seismic data is subtracted from the water seismic data to obtain an accurate mathematical expression of the downlink multiple wave field; the land seismic data is added to the water seismic data, and the seabed reflection coefficient Kr and water depth variables are introduced. After substituting the field water depth measurement results to eliminate the influence of the seawater depth variable, another mathematical expression of the downlink multiple waves related to the seabed reflection coefficient can be obtained. The downlink multiple wave energies calculated by the two methods are compared. When the energy error of the two reaches the minimum, the corresponding Kr is the accurate seabed reflection coefficient at that location.

[0031] In step 4, the land detector field is subtracted from the water detector field to obtain the downlink multiple wave energy expression formula:

[0032] 2 X ghost (t) = X geo (t)-X hyd (t) (1)

[0034] The only time difference between the downgoing multiple waves and the primary reflected waves is caused by the water depth, and their relationship is expressed as:

[0035] X ghost (t) = Z*X primary (t) (2)

[0037] Z is the two-way travel time Z transform expression of water depth:

[0038]

[0039] h is the water depth and v is the propagation speed of seismic waves in seawater.

[0040] In step 4, the water detector field is added to the land detector field to obtain the following expression:

[0041] X geo (t)+X hyd (t) = 2Z -1 *X ghost (t)-2K r *X ghost (t) (4)

[0043] By rearranging formula (4), another expression for the downgoing multiple wave can be obtained, which is related to the water depth and the seabed coefficient:

[0044] 2 X host (t)=(Z -1 -K r ) -1 *[X geo (t)+X hyd (t)] (5)

[0046] By comparing formula (1) with formula (5), we can obtain the downlink multiple wave energy error formula:

[0047] E=(Z -1 -K r ) -1 *[X geo (t)+X hyd (t)]-[X geo (t)-X hyd (t)] (6)

[0049] From field measurements, we can get accurate water depth data h. The propagation speed v of seismic waves in seawater is also fixed. Therefore, the K that minimizes the energy error E is r This is the accurate seafloor reflection coefficient.

[0050] In step 5, the land detection seismic data and the water detection seismic data are added and then the downgoing wave field with the seabed reflection coefficient as the proportional factor is subtracted to obtain a relatively pure upgoing wave field.

[0051] In step 5, after obtaining a relatively accurate seafloor reflection coefficient, the land-based seismic data and the water-based seismic data are added together, and then the downlink multiple wave fields with the seafloor reflection coefficient as the proportional factor are subtracted to obtain a relatively pure primary reflection wave field, which is based on the formula:

[0052] X geo (t)+X hyd (t) = 2X primary (t)-2K r *X ghost (t).

[0053] In step 6, the separated OBC seismic data downlink wave field and primary reflection wave field are subjected to predictive deconvolution pre-stack processing to further eliminate the interference of the shot end ringing vibration.

[0054] In step 7, the primary reflection wave field and the downgoing wave field are superimposed respectively to obtain a primary reflection wave superposition profile and a seabed first-order downgoing multiple wave superposition profile.

[0055] The method for rapid on-site merging and processing of OBC dual-detection seismic data in shallow waters of the present invention meets the requirements for comprehensively evaluating the quality of OBC dual-detection seismic data acquisition. The present invention performs phase correction based on the phase difference analysis results of OBC water detection and land detection to ensure the phase consistency of the two types of seismic data; analyzes the energy of OBC water detection and land detection, and then performs energy consistency correction. Due to the randomness of the contact relationship between OBC and the seabed, the energy of land detection seismic data will vary depending on the quality of the contact relationship. Affected by the built-in dual detection of the OBC device, especially the sensitivity of the piezoelectric ceramic piece, the energy of the water detection seismic data will also fluctuate. Therefore, the energy difference between OBC water detection and land detection seismic data is not a constant. It is necessary to calculate the energy ratio of OBC dual-detection seismic data channel by channel. Based on the calculated energy ratio coefficient, the land detection seismic data is energy-corrected to keep the capabilities of the land detection component and the water detection component of the OBC dual-detection seismic data consistent; in the land detection seismic data energy After the correction, the accurate mathematical expression of the downlink multiple wave field is obtained by subtracting the land inspection seismic data from the water inspection seismic data. Then the land inspection seismic data and the water inspection seismic data are added respectively, and the seafloor reflection coefficient Kr and the water depth variable are introduced. The field water depth measurement results are substituted to eliminate the water depth variable, and another mathematical expression of the downlink multiple wave related only to the seafloor reflection coefficient is obtained. The energy of the downlink multiple waves calculated by the two methods is compared. When the energy error between the two reaches the minimum, the corresponding Kr is the accurate seafloor reflection coefficient at that location. According to the calculated seafloor coefficient, the uplink and downlink wave fields are separated. For the separated uplink and downlink wave fields, the predictive deconvolution is used to suppress the gun end shock. After pre-stack processing, the uplink and downlink wave fields are superimposed respectively, so as to obtain a relatively pure first reflection wave superposition profile and a first-order seafloor multiple wave superposition profile. This method improves the time efficiency of the rapid merging and processing of OBC double-inspection seismic data at the field seismic data acquisition site, improves the quality of the on-site monitoring profile, and meets the quality control requirements of the OBC seismic data acquisition in shallow waters. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a flowchart of a specific embodiment of the method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data of the present invention;

[0057] Figure 2 This is a cross-section screenshot of the stacking of OBC double-detection seismic data after rapid merging and processing based on a work area in Bohai Bay (water depth 15m-20m) in a specific embodiment of the present invention;

[0058] Figure 3 This is a cross-section screenshot of the stacking of OBC double-detection seismic data after rapid merging and processing based on a work area (water depth 1.5m-10m) in Bohai Bay in a specific embodiment of the present invention;

[0059] Figure 4This is a screenshot of a superimposed profile after rapid merging and processing of OBC double-detection seismic data in a work area (water depth 50m-52m) in the Bay of Bengal in the Indian Ocean in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0060] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0061] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations and / or combinations thereof.

[0062] The method for rapidly merging and processing beach and shallow sea OBC double-detection seismic data on site of the present invention comprises:

[0063] Step 1: Analyze the phase difference of OBC water detection and land detection seismic data, and perform phase correction based on the analysis results. Usually, the phase difference between water detection and land detection seismic data is 90. ;

[0064] Step 2: Clean the OBC double-check seismic data to eliminate abnormal amplitude interference, bad tracks, etc.

[0065] Step 3: Count the energy of each sampling point of the OBC water inspection and land inspection seismic data one by one, and save them in seismic data format;

[0066] Step 4: Obtain the absolute value of the energy ratio of the OBC water detection and land detection calculated in step 3, perform moderate smoothing, and use it as the water detection and land detection energy correction proportional factor. Perform energy consistency processing on the OBC water detection and land detection seismic data based on the proportional factor.

[0067] Step 5: Separate the downlink multiple wave field by subtracting the water-detection seismic data from the land-detection seismic data;

[0068] Step 6: After the OBC water and land seismic data are processed for energy consistency, the seabed reflection coefficient is calculated based on the energy errors of the downlink multiple waves separated by different methods. The land seismic data is subtracted from the water seismic data to obtain an accurate mathematical expression of the downlink multiple wave field. The land seismic data is added to the water seismic data, and the seabed reflection coefficient Kr and water depth variables are introduced. After substituting the field water depth measurement results to eliminate the influence of the seawater depth variable, another mathematical expression of the downlink multiple waves related to the seabed reflection coefficient can be obtained. The energy of the downlink multiple waves calculated by the two methods is compared. When the energy error of the two reaches the minimum, the corresponding Kr is the accurate seabed reflection coefficient at that location;

[0069] Step 7: Add the land seismic data and the water seismic data and then subtract the downgoing wave field with the seabed reflection coefficient as the proportional factor to obtain a relatively pure upgoing wave field;

[0070] Step 8: Perform pre-stack processing such as predictive deconvolution on the separated OBC seismic data downlink wave field and primary reflection wave field to further eliminate the interference of the shot end ringing vibration;

[0071] Step 9: Superimpose the primary reflection wave field and the downgoing wave field respectively to obtain the primary reflection wave superposition profile and the seabed first-order downgoing multiple wave superposition profile.

[0072] The following are several specific embodiments of the present invention.

[0073] Example 1

[0074] In a specific embodiment 1 of the present invention, the embodiment is located in the Bohai Bay area, with a water depth of 15m-20m. The water detection component and the land detection component of the OBC dual-detection seismic data have a high signal-to-noise ratio and low noise interference. The merge processing implementation process is as follows: Figure 1 As shown, Figure 1 The flowchart of the method for rapidly merging and processing the OBC double-check seismic data in shallow waters of the present invention is as follows. The method for rapidly merging and processing the OBC double-check seismic data in shallow waters of the present invention comprises the following steps:

[0075] (1) Compare or perform phase analysis on the water and land seismic data from the same shot and channel to determine the phase difference between the OBC water and land seismic systems. Based on the analyzed phase difference, perform phase correction on the land seismic data to eliminate the impact of the phase difference of the OBC dual-seismic data on the processing results.

[0076] (2) Data purification is performed on OBC dual-detection seismic data to eliminate abnormal amplitude interference, bad channels, lazy jumps, etc. caused by equipment failure or leakage in individual seismic channels;

[0077] (3) The energy statistics method is used to count the energy of each sampling point of the OBC water detection and land detection seismic data. The water detection energy H i, Lujian Energy G i and save it in the format corresponding to the seismic data;

[0078] (4) Obtain the absolute value S of the statistical OBC water inspection and land inspection energy ratio i =|H i / G i |, the ratio is also saved in the format corresponding to the seismic data, and the sample points are smoothed according to the fluctuation amplitude of the ratio curve to eliminate the influence of outliers. The smoothing method is mean smoothing, and its formula is: For example, 5-point smoothing S avgi =(S i-2 +S i-1 +S i +S i+1 +S i+2 ) / 5, the ratio is used as the proportional factor for the energy correction of water detection and land detection. The energy correction of OBC land detection seismic data is carried out according to the proportional factor to make the energy of land detection seismic data consistent with that of water detection seismic data. The correction method is to multiply the land detection energy by the proportional coefficient, that is, G i =G i *S avgi ;

[0079] (5) The land seismic data is subtracted from the water seismic data to separate the downlink multiple wave field. The OBC water and land seismic data will simultaneously receive the primary reflection wave (X primary ), downward multiple waves are usually considered ghost waves (X ghost ), upgoing multiple waves (X pegleg ). According to the difference in polarity of water detection and land detection in sensing different types of earthquake wave fields, the water detection component and land detection component at the same location have different wave field responses. The wave field response of the water detection component is:

[0080] X hyd (t) = X primary (t)-X ghost (t)-X pegleg (t),

[0081] The wave field response of the land inspection component is:

[0082] X geo (t) = X primary (t)+X ghost (t)-X pegleg (t),

[0083] According to the OBC dual-detection field response formula, after the OBC water and land detection seismic data are processed for energy consistency, the land detection field is subtracted from the water detection field to separate the downlink multiple wave field. Since the sea surface reflection coefficient is large enough, it can be considered that the wave field is consistent with the energy of the primary reflection wave, with only the time difference caused by the sea depth.

[0084] (6) Based on the energy consistency processing of OBC water and land seismic data, the seabed reflection coefficient is calculated according to the energy error of the downlink multiple waves separated by different methods. Since the uplink multiple wave energy is not only related to the downlink multiple wave energy, but also to the seabed reflection coefficient, that is, X pegleg (t) = K r *X ghost (t)(K r is the seabed reflection coefficient), and the separation accuracy of the primary reflection wave depends on the separation accuracy of the uplink multiple waves. Therefore, the accurate separation of the primary reflection wave field and the uplink multiple wave field depends on the seabed reflection coefficient. Since the subtraction of the land detector field and the water detector field can obtain a definite downlink multiple wave field, the addition of the land detector field and the water detector field can also obtain the downlink multiple wave field after introducing the seabed reflection coefficient. The present invention calculates the seabed coefficient by judging the energy error of the downlink multiple waves separated by the two methods. The specific method is as follows. Subtract the land detector field from the water detector field to obtain the expression formula for the energy of the downlink multiple waves:

[0085] 2X ghost (t) = X geo (t)-X hyd (t) (1)

[0087] The only time difference between the downgoing multiple waves and the primary reflected waves is caused by the water depth, and their relationship is expressed as:

[0088] X ghost (t) = Z*X primary (t) (2)

[0090] Z is the two-way travel time Z transform expression of water depth:

[0091]

[0092] h is the water depth, v is the propagation speed of seismic waves in seawater

[0093] The water detection field and the land detection field are added to obtain the following expression:

[0094] X geo (t)+X hyd (t) = 2Z -1 *X ghost (t)-2K r *X ghost (t) (4)

[0096] By rearranging formula (4), another expression for the downgoing multiple wave can be obtained, which is related to the water depth and the seabed coefficient:

[0097] 2X ghost (t)=(Z -1 -K r ) -1 *[X geo (t)+X hyd (t)] (5)

[0099] By comparing formula (1) with formula (5), we can obtain the downlink multiple wave energy error formula:

[0100] E=(Z -1 -K r ) -1 *[X geo (t)+X hyd (t)]-[X geo (t)-X hyd (t)] (6)

[0102] From field measurements, we can get accurate water depth data h. The propagation speed v of seismic waves in seawater is also fixed. Therefore, the K that minimizes the energy error E is r This is the accurate seafloor reflection coefficient;

[0103] (7) After obtaining a relatively accurate seafloor reflection coefficient, the purer primary reflection wave field is obtained by subtracting the downlink multiple wave field with the seafloor reflection coefficient as the proportional factor from the land seismic data and the water seismic data. The formula is:

[0104] X geo (t)+X hyd (t) = 2X primary (t)-2K r *X ghost (t);

[0105] (8) Perform pre-stack processing such as predictive deconvolution on the separated primary reflection wave field and downlink multiple wave field of OBC seismic data to further eliminate the interference of shot end ringing vibration;

[0106] (9) The primary reflection wave field and the downlink multiple wave field are superimposed respectively to obtain the primary reflection wave superposition profile and the seafloor first-order downlink multiple wave superposition profile. The OBC double-detection seismic data merging processing effect of this embodiment is as follows: Figure 2 shown.

[0107] Example 2

[0108] In a specific embodiment 2 of the present invention, the embodiment is located in the Bohai Bay area, with a water depth of 1.5m-10m. Affected by the tide and the coupling quality of the land inspection data, the frequency of the land inspection component of the OBC dual-inspection seismic data is low and the noise interference is large. The merging process is as follows: Figure 1 As shown, Figure 1 The flowchart of the method for rapidly merging and processing the OBC double-check seismic data in shallow waters of the present invention is shown in FIG. The method for rapidly merging and processing the OBC double-check seismic data in shallow waters of the present invention comprises the following steps:

[0109] (1) Compare or perform phase analysis on the water and land seismic data from the same shot and channel to determine the phase difference between the OBC water and land seismic systems. Based on the analyzed phase difference, perform phase correction on the land seismic data to eliminate the impact of the phase difference of the OBC dual-seismic data on the processing results.

[0110] (2) Data purification is performed on OBC dual-detection seismic data to eliminate abnormal amplitude interference, bad channels, lazy jumps, etc. caused by equipment failure or leakage in individual seismic channels;

[0111] (3) The energy statistics method is used to count the energy of each sampling point of the OBC water detection and land detection seismic data. The water detection energy H i , Lujian Energy G i and save it in the format corresponding to the seismic data;

[0112] (4) Obtain the absolute value S of the statistical OBC water inspection and land inspection energy ratio i =|H i / G i |, the ratio is also saved in the format corresponding to the seismic data, and the sample points are smoothed according to the fluctuation amplitude of the ratio curve to eliminate the influence of outliers. The smoothing method is mean smoothing, and its formula is: For example, 5-point smoothing S avgi =(S i-2 +S i-1 +S i +S i+1 +S i+2 ) / 5, the ratio is used as the proportional factor for the energy correction of water detection and land detection. The energy correction of OBC land detection seismic data is carried out according to the proportional factor to make the energy of land detection seismic data consistent with that of water detection seismic data. The correction method is to multiply the land detection energy by the proportional coefficient, that is, G i =G i *S avgi ;

[0113] (5) The land seismic data is subtracted from the water seismic data to separate the downlink multiple wave field. The OBC water and land seismic data will simultaneously receive the primary reflection wave (X primary ), downward multiple waves are usually considered ghost waves (Xghost ), upgoing multiple waves (X pegleg ). According to the difference in polarity of water detection and land detection in sensing different types of earthquake wave fields, the water detection component and land detection component at the same location have different wave field responses. The wave field response of the water detection component is:

[0114] X hyd (t) = X primary (t)-X ghost (t)-X pegleg (t),

[0115] The wave field response of the land inspection component is:

[0116] X geo (t) = X primary (t)+X ghost (t)-X pegleg (t),

[0117] According to the OBC dual-detection field response formula, after the OBC water and land detection seismic data are processed for energy consistency, the land detection field is subtracted from the water detection field to separate the downlink multiple wave field. Since the sea surface reflection coefficient is large enough, it can be considered that the wave field is consistent with the energy of the primary reflection wave, with only the time difference caused by the sea depth.

[0118] (6) Based on the energy consistency processing of OBC water and land seismic data, the seabed reflection coefficient is calculated according to the energy error of the downlink multiple waves separated by different methods. Since the uplink multiple wave energy is not only related to the downlink multiple wave energy, but also to the seabed reflection coefficient, that is, X pegleg (t) = K r *X ghost (t)(K r is the seabed reflection coefficient), and the separation accuracy of the primary reflection wave depends on the separation accuracy of the uplink multiple waves. Therefore, the accurate separation of the primary reflection wave field and the uplink multiple wave field depends on the seabed reflection coefficient. Since the subtraction of the land detector field and the water detector field can obtain a definite downlink multiple wave field, the addition of the land detector field and the water detector field can also obtain the downlink multiple wave field after introducing the seabed reflection coefficient. The present invention calculates the seabed coefficient by judging the energy error of the downlink multiple waves separated by the two methods. The specific method is as follows. Subtract the land detector field from the water detector field to obtain the expression formula for the energy of the downlink multiple waves:

[0119] 2X ghost (t) = X geo (t)-X hyd (t) (1)

[0121] The only time difference between the downgoing multiple waves and the primary reflected waves is caused by the water depth, and their relationship is expressed as:

[0122] X ghost (t) = Z*X primary (t) (2)

[0124] Z is the two-way travel time Z transform expression of water depth:

[0125]

[0126] h is the water depth, v is the propagation speed of seismic waves in seawater

[0127] The water detection field and the land detection field are added to obtain the following expression:

[0128] X geo (t)+X hyd (t) = 2Z -1 *X ghost (t)-2K r *X ghost (t) (4)

[0130] By rearranging formula (4), another expression for the downgoing multiple wave can be obtained, which is related to the water depth and the seabed coefficient:

[0131] 2X ghost (t)=(Z -1 -K r ) -1 *[X geo (t)+X hyd (t)] (5)

[0133] By comparing formula (1) with formula (5), we can obtain the downlink multiple wave energy error formula:

[0134] E=(Z -1 -K r ) -1 *[X geo (t)+X hyd (t)]-[X geo (t)-X hyd (t)] (6)

[0135] From field measurements, we can get accurate water depth data h. The propagation speed v of seismic waves in seawater is also fixed. Therefore, the K that minimizes the energy error E is r This is the accurate seafloor reflection coefficient;

[0136] (7) After obtaining a relatively accurate seafloor reflection coefficient, the purer primary reflection wave field is obtained by subtracting the downlink multiple wave field with the seafloor reflection coefficient as the proportional factor from the land seismic data and the water seismic data. The formula is:

[0137] X geo (t)+X hyd (t) = 2X primary (t)-2K r *X ghost (t);

[0138] (8) Perform pre-stack processing such as predictive deconvolution on the separated primary reflection wave field and downlink multiple wave field of OBC seismic data to further eliminate the interference of shot end ringing vibration;

[0139] (9) The primary reflection wave field and the downlink multiple wave field are superimposed respectively to obtain the primary reflection wave superposition profile and the seafloor first-order downlink multiple wave superposition profile. The OBC double-detection seismic data merging processing effect of this embodiment is as follows: Figure 3 shown.

[0140] Example 3

[0141] In a specific embodiment 3 of the present invention, the embodiment is located in the Bay of Bengal in the Indian Ocean, with a water depth of 50m-52m. The water flow in the area is fast, and the land detection component of the OBC dual detection seismic data has a low signal-to-noise ratio and large noise interference. The merge processing implementation process is as follows Figure 1 As shown, Figure 1 The flowchart of the method for rapidly merging and processing the OBC double-check seismic data in shallow waters of the present invention is as follows. The method for rapidly merging and processing the OBC double-check seismic data in shallow waters of the present invention comprises the following steps:

[0142] (1) Compare or perform phase analysis on the water and land seismic data from the same shot and channel to determine the phase difference between the OBC water and land seismic systems. Based on the analyzed phase difference, perform phase correction on the land seismic data to eliminate the impact of the phase difference of the OBC dual-seismic data on the processing results.

[0143] (2) Data purification is performed on the OBC dual-detection seismic data to eliminate abnormal amplitude interference, bad channels, lazy jumps, etc. caused by equipment failure or leakage in individual seismic channels. On this basis, uniform parameters are used to perform moderate amplitude-preserving denoising on the water detection component and land detection component of the OBC dual-detection seismic data. Subsequent processing is performed on the basis of moderate amplitude-preserving denoising to eliminate the influence of noise on the OBC dual-detection merging processing effect.

[0144] (3) The energy statistics method is used to count the energy of each sampling point of the OBC water detection and land detection seismic data. The water detection energy H i , Lujian Energy G iand save it in the format corresponding to the seismic data;

[0145] (4) Obtain the absolute value S of the statistical OBC water inspection and land inspection energy ratio i =|H i / G i |, the ratio is also saved in the format corresponding to the seismic data, and the sample points are smoothed according to the fluctuation amplitude of the ratio curve to eliminate the influence of outliers. The smoothing method is mean smoothing, and its formula is: For example, 5-point smoothing S avgi =(S i-2 +S i-1 +S i +S i+1 +S i+2 ) / 5, the ratio is used as the proportional factor for the energy correction of water detection and land detection. The energy correction of OBC land detection seismic data is carried out according to the proportional factor to make the energy of land detection seismic data consistent with that of water detection seismic data. The correction method is to multiply the land detection energy by the proportional coefficient, that is, G i =G i *S avgi ;

[0146] (5) The land seismic data is subtracted from the water seismic data to separate the downlink multiple wave field. The OBC water and land seismic data will simultaneously receive the primary reflection wave (X primary ), downward multiple waves are usually considered ghost waves (X ghost ), upgoing multiple waves (X pegleg ). According to the difference in polarity of water detection and land detection in sensing different types of earthquake wave fields, the water detection component and land detection component at the same location have different wave field responses. The wave field response of the water detection component is:

[0147] X hyd (t) = X primary (t)-X ghost (t)-X pegleg (t),

[0148] The wave field response of the land inspection component is:

[0149] X geo (t) = X primary (t)+X ghost (t)-X pegleg (t),

[0150] According to the OBC dual-detection field response formula, after the OBC water and land detection seismic data are processed for energy consistency, the land detection field is subtracted from the water detection field to separate the downlink multiple wave field. Since the sea surface reflection coefficient is large enough, it can be considered that the wave field is consistent with the energy of the primary reflection wave, with only the time difference caused by the sea depth.

[0151] (6) Based on the energy consistency processing of OBC water and land seismic data, the seabed reflection coefficient is calculated according to the energy error of the downlink multiple waves separated by different methods. Since the uplink multiple wave energy is not only related to the downlink multiple wave energy, but also to the seabed reflection coefficient, that is, X pegleg (t) = K r *X ghost (t)(K r is the seabed reflection coefficient), and the separation accuracy of the primary reflection wave depends on the separation accuracy of the uplink multiple waves. Therefore, the accurate separation of the primary reflection wave field and the uplink multiple wave field depends on the seabed reflection coefficient. Since the subtraction of the land detector field and the water detector field can obtain a definite downlink multiple wave field, the addition of the land detector field and the water detector field can also obtain the downlink multiple wave field after introducing the seabed reflection coefficient. The present invention calculates the seabed coefficient by judging the energy error of the downlink multiple waves separated by the two methods. The specific method is as follows. Subtract the land detector field from the water detector field to obtain the expression formula for the energy of the downlink multiple waves:

[0152] 2X ghost (t) = X geo (t)-X hyd (t) (1)

[0154] The only time difference between the downgoing multiple waves and the primary reflected waves is caused by the water depth, and their relationship is expressed as:

[0155] X ghost (t) = Z*X primary (t) (2)

[0157] Z is the two-way travel time Z transform expression of water depth:

[0158]

[0159] h is the water depth, v is the propagation speed of seismic waves in seawater

[0160] The water detection field and the land detection field are added to obtain the following expression:

[0161] X geo (t)+X hyd (t) = 2Z -1 *X ghost (t)-2K r *X ghost (t) (4)

[0163] By rearranging formula (4), another expression for the downgoing multiple wave can be obtained, which is related to the water depth and the seabed coefficient:

[0164] 2Xghost (t)=(Z -1 -K r ) -1 *[X geo (t)+X hyd (t)] (5)

[0166] By comparing formula (1) with formula (5), we can obtain the downlink multiple wave energy error formula:

[0167] E=(Z -1 -K r ) -1 *[X geo (t)+X hyd (t)]-[X geo (t)-X hyd (t)] (6)

[0169] From field measurements, we can get accurate water depth data h. The propagation speed v of seismic waves in seawater is also fixed. Therefore, the K that minimizes the energy error E is r This is the accurate seafloor reflection coefficient;

[0170] (7) After obtaining a relatively accurate seafloor reflection coefficient, the purer primary reflection wave field is obtained by subtracting the downlink multiple wave field with the seafloor reflection coefficient as the proportional factor from the land seismic data and the water seismic data. The formula is:

[0171] X geo (t)+X hyd (t) = 2X primary (t)-2K r *X ghost (t);

[0172] (8) Perform pre-stack processing such as predictive deconvolution on the separated primary reflection wave field and downlink multiple wave field of OBC seismic data to further eliminate the interference of shot end ringing vibration;

[0173] (9) The primary reflection wave field and the downlink multiple wave field are superimposed respectively to obtain the primary reflection wave superposition profile and the seafloor first-order downlink multiple wave superposition profile. The OBC double-detection seismic data merging processing effect of this embodiment is as follows: Figure 4 shown.

[0174] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0175] Except for the technical features described in the specification, all other technical features are known technologies to those skilled in the art.

Claims

1. On-site rapid merging and processing method of OBC double-detection seismic data in shallow waters, It is characterized in that The on-site rapid merging and processing method of the shallow sea OBC double-detection seismic data includes: Step 1, purify the OBC double-check seismic data; Step 2, perform energy consistency processing on the OBC water inspection and land inspection seismic data; Step 3, separating and obtaining the downlink multiple wave field; Step 4, calculate the seabed reflection coefficient; Step 5, calculate and obtain a relatively pure upgoing wave field; Step 6, eliminating the interference of the cannon end sound vibration; Step 7, superimpose to obtain the first reflection wave superposition profile and the seabed first-order downgoing multiple wave superposition profile.

2. The on-site rapid merging and processing method for shallow-water OBC double-detection seismic data according to claim 1, It is characterized in that The method for rapidly merging and processing the shallow-water OBC double-detection seismic data on site also includes, before step 1, inputting the OBC double-detection seismic data and performing phase correction on the land-detection seismic data.

3. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 2, It is characterized in that When performing phase correction on land inspection seismic data, comparison or phase analysis of water inspection and land inspection seismic data from the same shot and channel is used to determine the phase difference between the OBC water inspection and land inspection systems. Based on the analyzed phase difference results, phase correction is performed on the land inspection seismic data to eliminate the impact of the phase difference of the OBC double inspection seismic data on the processing results.

4. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 1, It is characterized in that In step 1, the OBC double-check seismic data is cleaned to eliminate abnormal amplitude interference and the influence of bad tracks.

5. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 1, It is characterized in that The method for rapid on-site merging and processing of shallow-water OBC dual-detection seismic data also includes, after step 1, using an energy statistics method to count the energy of each sampling point of the OBC water detection and land detection seismic data one by one, and the water detection energy H i , Lujian Energy G i and saved in the format corresponding to the earthquake data.

6. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 5, It is characterized in that In step 2, the absolute value of the statistical OBC water detection and land detection energy ratio is obtained and moderately smoothed as the water detection and land detection energy correction proportional factor. Based on the proportional factor, the OBC water detection and land detection seismic data are processed for energy consistency.

7. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 6, It is characterized in that In step 2, obtain the statistical OBC water detection energy H i 、Lujian Energy G i The absolute value of the ratio S i =|H i / G i |, the ratio is also saved in the format corresponding to the seismic data, and the sample points are smoothed according to the fluctuation amplitude of the ratio curve to eliminate the influence of outliers.

8. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 7, It is characterized in that In step 2, the smoothing method is mean smoothing, and its formula is n is the smoothing parameter of seismic data sample points. Sample point smoothing is mainly to eliminate the influence of abnormal amplitude on merging processing. This ratio is used as the proportional factor for water detection and land detection energy correction. According to this proportional factor, the energy of OBC land detection seismic data is corrected to make the energy of land detection seismic data consistent with that of water detection seismic data. The correction method is to multiply the land detection energy by the proportional coefficient, that is, G i =G i *S avg。 9. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 1, It is characterized in that In step 3, the land inspection seismic data is subtracted from the water inspection seismic data to separate the downlink multiple wave field. The OBC water inspection and land inspection will simultaneously receive the primary reflection wave X primary , downward multiple waves are usually considered ghost waves X ghost , Upward Multiple Waves X pegleg ; According to the difference in polarity of water detection and land detection in sensing different types of earthquake wave fields, the water detection component and land detection component at the same location have different wave field responses. The wave field response of the water detection component is: X hyd (t)=X primary (t)-X ghost (t)-X pegleg (t), The wave field response of the land inspection component is: X geo (t)=X primary (t)+X ghost (t)-X pegleg (t), According to the OBC dual-detection field response formula, after the energy consistency processing of the OBC water and land detection seismic data, the land detection field is subtracted from the water detection field to separate the downlink multiple wave field. Since the sea surface reflection coefficient is large enough, it can be considered that the wave field is consistent with the energy of the primary reflection wave, with only the time difference caused by the sea depth.

10. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 9, It is characterized in that In step 4, after the OBC water and land seismic data are processed for energy consistency, the seabed reflection coefficient is calculated based on the energy errors of the downlink multiple waves separated by different methods; the land seismic data is subtracted from the water seismic data to obtain an accurate mathematical expression of the downlink multiple wave field; the land seismic data is added to the water seismic data, and the seabed reflection coefficient Kr and water depth variables are introduced. After substituting the field water depth measurement results to eliminate the influence of the seawater depth variable, another mathematical expression of the downlink multiple waves related to the seabed reflection coefficient can be obtained. The downlink multiple wave energies calculated by the two methods are compared. When the energy error of the two reaches the minimum, the corresponding Kr is the accurate seabed reflection coefficient at that location.

11. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 10, It is characterized in that In step 4, the land detector field is subtracted from the water detector field to obtain the downlink multiple wave energy expression formula: 2X ghost (t)=X geo (t)-X hyd (t) (1) The only time difference between the downgoing multiple waves and the primary reflected waves is caused by the water depth, and their relationship is expressed as: X ghost (t)=Z*X primary (t) (2) Z is the two-way travel time Z transform expression of water depth: h is the water depth and v is the propagation speed of seismic waves in seawater.

12. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 11, It is characterized in that In step 4, the water detector field is added to the land detector field to obtain the following expression: X geo (t)+X hyd (t)=2Z -1 *X ghost (t)-2K r *X ghost (t) (4) By rearranging formula (4), another expression for the downgoing multiple wave can be obtained, which is related to the water depth and the seabed coefficient: 2X ghost (t)=(Z -1 -K r ) -1 *[X geo (t)+X hyd (t)] (5) By comparing formula (1) with formula (5), we can obtain the downlink multiple wave energy error formula: E=(Z -1 -K r ) -1 *[X geo (t)+X hyd (t)]-[X geo (t)-X hyd (t)] (6) From field measurements, we can get accurate water depth data h. The propagation speed v of seismic waves in seawater is also fixed. Therefore, the K that minimizes the energy error E is r This is the accurate seafloor reflection coefficient.

13. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 12, It is characterized in that In step 5, the land detection seismic data and the water detection seismic data are added and then the downgoing wave field with the seabed reflection coefficient as the proportional factor is subtracted to obtain a relatively pure upgoing wave field.

14. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 13, It is characterized in that In step 5, after obtaining a relatively accurate seafloor reflection coefficient, the land-based seismic data and the water-based seismic data are added together, and then the downlink multiple wave fields with the seafloor reflection coefficient as the proportional factor are subtracted to obtain a relatively pure primary reflection wave field, which is based on the formula: X geo (t)+X hyd (t)=2X primary (t)-2K r *X ghost (t)。 15. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 1, It is characterized in that In step 6, the separated OBC seismic data downlink wave field and primary reflection wave field are subjected to predictive deconvolution pre-stack processing to further eliminate the interference of the shot end ringing vibration.

16. The method for rapid on-site merging and processing of shallow-water OBC double-detection seismic data according to claim 1, It is characterized in that In step 7, the primary reflection wave field and the downgoing wave field are superimposed respectively to obtain a primary reflection wave superposition profile and a seabed first-order downgoing multiple wave superposition profile.

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