The near-seabed multichannel seismic exploration systems have yielded remarkable successes in marine geological disaster assessment,marine gas hydrate investigation,and deep-sea mineral exploration owing to their high...The near-seabed multichannel seismic exploration systems have yielded remarkable successes in marine geological disaster assessment,marine gas hydrate investigation,and deep-sea mineral exploration owing to their high vertical and horizontal resolution.However,the quality of deep-towed seismic imaging hinges on accurate source-receiver positioning information.In light of existing technical problems,we propose a novel array geometry inversion method tailored for high-resolution deep-towed multichannel seismic exploration systems.This method is independent of the attitude and depth sensors along a deep-towed seismic streamer,accounting for variations in seawater velocity and seabed slope angle.Our approach decomposes the towed line array into multiline segments and characterizes its geometric shape using the line segment distance and pitch angle.Introducing optimization parameters for seawater velocity and seabed slope angle,we establish an objective function based on the model,yielding results that align with objective reality.Employing the particle swarm optimization algorithm enables synchronous acquisition of optimized inversion results for array geometry and seawater velocity.Experimental validation using theoretical models and practical data verifies that our approach effectively enhances source and receiver positioning inversion accuracy.The algorithm exhibits robust stability and reliability,addressing uncertainties in seismic traveltime picking and complex seabed topography conditions.展开更多
A profile of shallow crustal velocity structure(1–2 km) may greatly enhance interpretation of the sedimentary environment and shallow tectonic deformation.Recent advances in surface wave tomography, using ambient noi...A profile of shallow crustal velocity structure(1–2 km) may greatly enhance interpretation of the sedimentary environment and shallow tectonic deformation.Recent advances in surface wave tomography, using ambient noise data recorded with high-density seismic arrays, have improved the understanding of regional crustal structure. As the interest in detailed shallow crustal structure imaging has increased, dense seismic array methods have become increasingly efficient. This study used a high-density seismic array deployed in the Xinjiang basin in southeastern China, to record seismic data, which was then processed with the ambient noise tomography method. The high-density seismic array contained 203 short-period seismometers, spaced at short intervals(~ 400 m). The array collected continuous records of ambient noise for 32 days. Data preprocessing,cross correlation calculation, and Rayleigh surface wave phase-velocity dispersion curve extraction, yielded more than 16,000 Rayleigh surface wave phase-velocity dispersion curves, which were then analyzed using the direct-inversion method. Checkerboard tests indicate that the shear wave velocity is recovered in the study area, at depths of 0–1.4 km,with a lateral image resolution of ~ 400 m. Model test results show that the seismic array effectively images a 50 m thick slab at a depth of 0–300 m, a 150 m thick anomalous body at a depth of 300–600 m, and a 400 m thick anomalous body at a depth of 0.6–1.4 km. The shear wave velocity profile reveals features very similar to those detected by a deep seismic reflection profile across the study area. This demonstrates that analysis of shallow crustal velocity structure provides high-resolution imaging of crustal features.Thus, ambient noise tomography with a high-density seismic array may play an important role in imaging shallow crustal structure.展开更多
In China, most oil fields are continental sedimentation with strong heterogeneity, which on one side makes the reservoir prospecting and development more difficult, but on the other side provides more space for search...In China, most oil fields are continental sedimentation with strong heterogeneity, which on one side makes the reservoir prospecting and development more difficult, but on the other side provides more space for searching residual oil in matured fields. Time-lapse seismic reservoir monitoring technique is one of most important techniques to define residual oil distribution. According to the demand for and development of time-lapse seismic reservoir monitoring in China, purposeless repeated acquisition time-lapse seismic data processing was studied. The four key steps in purposeless repeated acquisition time-lapse seismic data processing, including amplitude-preserved processing with relative consistency, rebinning, match filtering and difference calculation, were analyzed by combining theory and real seismic data processing. Meanwhile, quality control during real time-lapse seismic processing was emphasized.展开更多
Acquisition footprint is a new concept to describe the seismic noise in three-dimensional seismic exploration and it is closely related to geometry and observation shuttering. At present, the study on acquisition foot...Acquisition footprint is a new concept to describe the seismic noise in three-dimensional seismic exploration and it is closely related to geometry and observation shuttering. At present, the study on acquisition footprints has become a hot spot. In partnership with the Dagang Oilfield, we used the channel sand body seismic physical model to study the characteristics of wide/narrow azimuth acquisition footprints and analyzed and compared the two types of footprints and their effects on target imaging. In addition, the footprints caused by data processing of the normal moveout offset (NMO) stretching aberration were discussed. These footprints are located only in the shallow or middle layer in the time slice, and possibly affect the imaging of shallow target layers, and have no influence on deep target imaging. Seismic physical modeling has its advantages in the study of acquisition footprints.展开更多
The construction of major marine infrastructure projects and the exploration and development of deep-sea mineral resources require fine imaging of seabed strata and structures.The highresolution marine seismic explora...The construction of major marine infrastructure projects and the exploration and development of deep-sea mineral resources require fine imaging of seabed strata and structures.The highresolution marine seismic exploration based on a high broadband sparker source is an important approach to reveal seabed stratum and reservoir structure,and identify geohazard.To optimize the performance of sparker seismic source,we investigated the electro-acoustic characteristics of spark discharge under conditions of different charging voltages and electrode numbers.Results show that the sound source level increased with the increase of the charging voltage,whereas the main frequency decreased when the charging voltage increases.In addition,it was found that the charging capacitance had more obvious influence on the main frequency than the sound source level did.Although the load energy decreased with increasing electrode number,the sound source level still increased but the main frequency decreased.Meanwhile,the primary to bubble(P/B)ratio increased with the increase of the electrode number.To gain a deeper insight into the electro-acoustic characteristics,we investigate the relationship between sound source level and power peak,from which a good correlation was observed.A more practical statistical analysis on the rise rate of current was processed,and a perfect logarithmic function was derived.Furthermore,we found that the main frequency was most possibly subjected to the electrical energy,especially the charging energy per electrode.The results indicate that the charging energy per electrode less than 10 J could increase the main frequency to above 300 Hz.At last,the main frequency could be reduced to 20 Hz when the charging energy of a single-electrode discharge was enhanced to over 4 kJ.This study shall be helpful in developing a sparker seismic source and improving the performance for marine engineering exploration and geohazard assessment.展开更多
The pattern of the subtle traps, in which oil and gas accumulated, in the buried-hill faulted zone in the Jiyang sag is very complicated, and very hard to prospect. The paper analyses the main difficulties in explorin...The pattern of the subtle traps, in which oil and gas accumulated, in the buried-hill faulted zone in the Jiyang sag is very complicated, and very hard to prospect. The paper analyses the main difficulties in exploring the complicated buried-hill faulted zone of the area from a point of geology.The typical pattern of the buried-hill zone in the Jiyang sag is studied using the forward modeling.Target-orient layout design and full 3-D seismic technology, which are useful for oil and gas exploration on the zone, are put forward. Taking the exploration for oil and gas traps on the zone as an example, certain technologies and the effect of their applications about the design for target acquisition,acquisition on a wide-azimuth, point sources and point receivers are discussed.展开更多
The significance of detection of urban active faults and the general situation concerning detection of urban active faults in the world are briefly introduced. In a brief description of the basic principles of anti-di...The significance of detection of urban active faults and the general situation concerning detection of urban active faults in the world are briefly introduced. In a brief description of the basic principles of anti-disturbance and high-resolution shallow seismic exploration, the stress is put on the excitation of seismic sources, the performance of digital seismographs, receiving mode and conditions, geometry as well as data acquisition, processing and interpretation in the anti-disturbance and high-resolution shallow seismic exploration of urban active faults. The study indicates that a controlled seismic source with a linear or nonlinear frequency-conversion scanning function and the relevant seismographs must be used in data acquisition, as well as working methods for small group interval, small offset, multi-channel receiving, short-array and high-frequency detectors for receiving are used. Attention should be paid to the application of techniques for static correction of refraction, noise suppressing, high-precision analysis of velocity, wavelet compressing, zero-phasing of wavelet and pre-stacking migration to data processing and interpretation. Finally, some cases of anti-disturbance and high-resolution shallow seismic exploration of urban active faults are present in the paper.展开更多
According to the actual observation conditions of the Yangtze River valley from Anqing city to Maanshan city,we designed the 3D acquisition geometry,and applied the multi-scale checkerboard semblance analysis to asses...According to the actual observation conditions of the Yangtze River valley from Anqing city to Maanshan city,we designed the 3D acquisition geometry,and applied the multi-scale checkerboard semblance analysis to assess the preliminary resolution of the designed observation.The checkerboard semblance tests use the refraction and reflection travel-time simultaneous inversion algorithm to quantitatively provide both resolution assessment of velocity structure and Moho topography.The multi-scale checker-board semblance recovery results show that while the chec-kerboard semblance threshold value is 0.5,the preliminary resolution of the designed acquisition geometry is better than 10 km in the upper crust(the depth is less than 10 km),around 15 km in the mid-crust(the depth is 10?25 km),and better than 20 km in the lower crust(the depth is 25?33 km).The preliminary tomographic resolution for the Moho topography is about 20 km in the ray-path coverage area beneath the acquisition geometry.While the checkerboard semblance threshold value is 0.75,the preliminary resolution is 20 km in the upper crust,around 20?25 km in the mid-crust and 25 km in the lower crust.And the preliminary tomographic resolution for the Moho topography is better than 30 km in the ray-path coverage area beneath the acquisition geometry.These non-linear checkerboard tests reveal that the designed acquisition geometry is suitable to image the crustal velocity structure of the Yangtze River valley in the Anhui province.展开更多
A seismometer data acquisition unit has been used in the Changping seismic station to record the output of a strainmeter.The output of a strainmeter was sampled at a rate of 100/sec by seismometer acquisition from the...A seismometer data acquisition unit has been used in the Changping seismic station to record the output of a strainmeter.The output of a strainmeter was sampled at a rate of 100/sec by seismometer acquisition from the original rate of 1 per minute.Plenty of high frequency sampled data was recorded.The minute value curve calculated from the seismometer acquisition are consistent with that of the original data sampled by the strain acquisition system.More complete waveforms were recorded with a higher sampling rate,and seismic phase parameters calculated by using higher sampling rate strain seismic waves are also in consistency with the results of its predecessors.Spectra of the strain seismic waves are compared with that of seismic waves recorded by a seismometer in the Shisanling seismic station,and their trends are almost the same.Besides,some lower frequency components still exist in strain seismic waves.展开更多
The dynamic range of the currently most widely used 24-bit seismic data acquisition devices is 10–20 d B lower than that of broadband seismometers, and this can affect the completeness of seismic waveform recordings ...The dynamic range of the currently most widely used 24-bit seismic data acquisition devices is 10–20 d B lower than that of broadband seismometers, and this can affect the completeness of seismic waveform recordings under certain conditions. However, this problem is not easy to solve because of the lack of analog to digital converter(ADC) chips with more than 24 bits in the market. In this paper, we propose a method in which an adder, an integrator, a digital to analog converter chip, a field-programmable gate array, and an existing low-resolution ADC chip are used to build a third-order 16-bit oversampling delta-sigma modulator. This modulator is equipped with a digital decimation filter, thus facilitating higher resolution and larger dynamic range seismic data acquisition. Experimental results show that, within the 0.1–40 Hz frequency range, the circuit board's dynamic range reaches 158.2 d B, its resolution reaches 25.99 bits, and its linearity error is below 2.5 ppm, which is better than what is achieved by the commercial 24-bit ADC chips ADS1281 and CS5371. This demonstrates that the proposed method may alleviate or even completely resolve the amplitude-limitation problem that so commonly occurs with broadband observation instruments during strong earthquakes.展开更多
基金supported by the special funds of Laoshan Laboratory(No.LSKJ202203604)the National Key Research and Development Program of China(No.2016 YFC0303901).
文摘The near-seabed multichannel seismic exploration systems have yielded remarkable successes in marine geological disaster assessment,marine gas hydrate investigation,and deep-sea mineral exploration owing to their high vertical and horizontal resolution.However,the quality of deep-towed seismic imaging hinges on accurate source-receiver positioning information.In light of existing technical problems,we propose a novel array geometry inversion method tailored for high-resolution deep-towed multichannel seismic exploration systems.This method is independent of the attitude and depth sensors along a deep-towed seismic streamer,accounting for variations in seawater velocity and seabed slope angle.Our approach decomposes the towed line array into multiline segments and characterizes its geometric shape using the line segment distance and pitch angle.Introducing optimization parameters for seawater velocity and seabed slope angle,we establish an objective function based on the model,yielding results that align with objective reality.Employing the particle swarm optimization algorithm enables synchronous acquisition of optimized inversion results for array geometry and seawater velocity.Experimental validation using theoretical models and practical data verifies that our approach effectively enhances source and receiver positioning inversion accuracy.The algorithm exhibits robust stability and reliability,addressing uncertainties in seismic traveltime picking and complex seabed topography conditions.
基金supported by the China Geological Survey Project“Deep Geological Survey of the Qin-Hang Belt”(No.DD20160082)the National Natural Science Foundation of China(No.41574048)
文摘A profile of shallow crustal velocity structure(1–2 km) may greatly enhance interpretation of the sedimentary environment and shallow tectonic deformation.Recent advances in surface wave tomography, using ambient noise data recorded with high-density seismic arrays, have improved the understanding of regional crustal structure. As the interest in detailed shallow crustal structure imaging has increased, dense seismic array methods have become increasingly efficient. This study used a high-density seismic array deployed in the Xinjiang basin in southeastern China, to record seismic data, which was then processed with the ambient noise tomography method. The high-density seismic array contained 203 short-period seismometers, spaced at short intervals(~ 400 m). The array collected continuous records of ambient noise for 32 days. Data preprocessing,cross correlation calculation, and Rayleigh surface wave phase-velocity dispersion curve extraction, yielded more than 16,000 Rayleigh surface wave phase-velocity dispersion curves, which were then analyzed using the direct-inversion method. Checkerboard tests indicate that the shear wave velocity is recovered in the study area, at depths of 0–1.4 km,with a lateral image resolution of ~ 400 m. Model test results show that the seismic array effectively images a 50 m thick slab at a depth of 0–300 m, a 150 m thick anomalous body at a depth of 300–600 m, and a 400 m thick anomalous body at a depth of 0.6–1.4 km. The shear wave velocity profile reveals features very similar to those detected by a deep seismic reflection profile across the study area. This demonstrates that analysis of shallow crustal velocity structure provides high-resolution imaging of crustal features.Thus, ambient noise tomography with a high-density seismic array may play an important role in imaging shallow crustal structure.
文摘In China, most oil fields are continental sedimentation with strong heterogeneity, which on one side makes the reservoir prospecting and development more difficult, but on the other side provides more space for searching residual oil in matured fields. Time-lapse seismic reservoir monitoring technique is one of most important techniques to define residual oil distribution. According to the demand for and development of time-lapse seismic reservoir monitoring in China, purposeless repeated acquisition time-lapse seismic data processing was studied. The four key steps in purposeless repeated acquisition time-lapse seismic data processing, including amplitude-preserved processing with relative consistency, rebinning, match filtering and difference calculation, were analyzed by combining theory and real seismic data processing. Meanwhile, quality control during real time-lapse seismic processing was emphasized.
基金Heterogeneous formation geophysical response characteristics (973 Program, subject number: 2007CB209601)Continental reservoir seismic physical model (CNPC Fundamental Research Projects, subject number: 06A10102)
文摘Acquisition footprint is a new concept to describe the seismic noise in three-dimensional seismic exploration and it is closely related to geometry and observation shuttering. At present, the study on acquisition footprints has become a hot spot. In partnership with the Dagang Oilfield, we used the channel sand body seismic physical model to study the characteristics of wide/narrow azimuth acquisition footprints and analyzed and compared the two types of footprints and their effects on target imaging. In addition, the footprints caused by data processing of the normal moveout offset (NMO) stretching aberration were discussed. These footprints are located only in the shallow or middle layer in the time slice, and possibly affect the imaging of shallow target layers, and have no influence on deep target imaging. Seismic physical modeling has its advantages in the study of acquisition footprints.
基金Supported by the National Natural Science Foundation of China(No.42276195)the Natural Science Foundation of Zhejiang Province(No.LQ22D060006)the Science Foundation of Zhejiang Sci-Tech University(No.21022092-Y)。
文摘The construction of major marine infrastructure projects and the exploration and development of deep-sea mineral resources require fine imaging of seabed strata and structures.The highresolution marine seismic exploration based on a high broadband sparker source is an important approach to reveal seabed stratum and reservoir structure,and identify geohazard.To optimize the performance of sparker seismic source,we investigated the electro-acoustic characteristics of spark discharge under conditions of different charging voltages and electrode numbers.Results show that the sound source level increased with the increase of the charging voltage,whereas the main frequency decreased when the charging voltage increases.In addition,it was found that the charging capacitance had more obvious influence on the main frequency than the sound source level did.Although the load energy decreased with increasing electrode number,the sound source level still increased but the main frequency decreased.Meanwhile,the primary to bubble(P/B)ratio increased with the increase of the electrode number.To gain a deeper insight into the electro-acoustic characteristics,we investigate the relationship between sound source level and power peak,from which a good correlation was observed.A more practical statistical analysis on the rise rate of current was processed,and a perfect logarithmic function was derived.Furthermore,we found that the main frequency was most possibly subjected to the electrical energy,especially the charging energy per electrode.The results indicate that the charging energy per electrode less than 10 J could increase the main frequency to above 300 Hz.At last,the main frequency could be reduced to 20 Hz when the charging energy of a single-electrode discharge was enhanced to over 4 kJ.This study shall be helpful in developing a sparker seismic source and improving the performance for marine engineering exploration and geohazard assessment.
文摘The pattern of the subtle traps, in which oil and gas accumulated, in the buried-hill faulted zone in the Jiyang sag is very complicated, and very hard to prospect. The paper analyses the main difficulties in exploring the complicated buried-hill faulted zone of the area from a point of geology.The typical pattern of the buried-hill zone in the Jiyang sag is studied using the forward modeling.Target-orient layout design and full 3-D seismic technology, which are useful for oil and gas exploration on the zone, are put forward. Taking the exploration for oil and gas traps on the zone as an example, certain technologies and the effect of their applications about the design for target acquisition,acquisition on a wide-azimuth, point sources and point receivers are discussed.
文摘The significance of detection of urban active faults and the general situation concerning detection of urban active faults in the world are briefly introduced. In a brief description of the basic principles of anti-disturbance and high-resolution shallow seismic exploration, the stress is put on the excitation of seismic sources, the performance of digital seismographs, receiving mode and conditions, geometry as well as data acquisition, processing and interpretation in the anti-disturbance and high-resolution shallow seismic exploration of urban active faults. The study indicates that a controlled seismic source with a linear or nonlinear frequency-conversion scanning function and the relevant seismographs must be used in data acquisition, as well as working methods for small group interval, small offset, multi-channel receiving, short-array and high-frequency detectors for receiving are used. Attention should be paid to the application of techniques for static correction of refraction, noise suppressing, high-precision analysis of velocity, wavelet compressing, zero-phasing of wavelet and pre-stacking migration to data processing and interpretation. Finally, some cases of anti-disturbance and high-resolution shallow seismic exploration of urban active faults are present in the paper.
基金The study is supported by National Natural Science Foundation of China(No.41774071).
文摘According to the actual observation conditions of the Yangtze River valley from Anqing city to Maanshan city,we designed the 3D acquisition geometry,and applied the multi-scale checkerboard semblance analysis to assess the preliminary resolution of the designed observation.The checkerboard semblance tests use the refraction and reflection travel-time simultaneous inversion algorithm to quantitatively provide both resolution assessment of velocity structure and Moho topography.The multi-scale checker-board semblance recovery results show that while the chec-kerboard semblance threshold value is 0.5,the preliminary resolution of the designed acquisition geometry is better than 10 km in the upper crust(the depth is less than 10 km),around 15 km in the mid-crust(the depth is 10?25 km),and better than 20 km in the lower crust(the depth is 25?33 km).The preliminary tomographic resolution for the Moho topography is about 20 km in the ray-path coverage area beneath the acquisition geometry.While the checkerboard semblance threshold value is 0.75,the preliminary resolution is 20 km in the upper crust,around 20?25 km in the mid-crust and 25 km in the lower crust.And the preliminary tomographic resolution for the Moho topography is better than 30 km in the ray-path coverage area beneath the acquisition geometry.These non-linear checkerboard tests reveal that the designed acquisition geometry is suitable to image the crustal velocity structure of the Yangtze River valley in the Anhui province.
基金sponsored by Central Public-interest Scientific Institution Basic Research Fund of Institute of Crustal Dynamics,CEA(ZDJ2008-40,ZDJ2010-15)
文摘A seismometer data acquisition unit has been used in the Changping seismic station to record the output of a strainmeter.The output of a strainmeter was sampled at a rate of 100/sec by seismometer acquisition from the original rate of 1 per minute.Plenty of high frequency sampled data was recorded.The minute value curve calculated from the seismometer acquisition are consistent with that of the original data sampled by the strain acquisition system.More complete waveforms were recorded with a higher sampling rate,and seismic phase parameters calculated by using higher sampling rate strain seismic waves are also in consistency with the results of its predecessors.Spectra of the strain seismic waves are compared with that of seismic waves recorded by a seismometer in the Shisanling seismic station,and their trends are almost the same.Besides,some lower frequency components still exist in strain seismic waves.
基金supported by the National Natural Science Foundation of China(Grant No.41404142)the National Science and Technology Support Plan Project(Grant No.2012BAF14B12)+1 种基金the Basic Research Projects of Institute of Earthquake Science,CEA(Grant Nos.2014IES0201,2011IES0203&2015IES0406)the Earthquake Monitoring and Prediction Project,CEA(Grant No.16A46ZX262)
文摘The dynamic range of the currently most widely used 24-bit seismic data acquisition devices is 10–20 d B lower than that of broadband seismometers, and this can affect the completeness of seismic waveform recordings under certain conditions. However, this problem is not easy to solve because of the lack of analog to digital converter(ADC) chips with more than 24 bits in the market. In this paper, we propose a method in which an adder, an integrator, a digital to analog converter chip, a field-programmable gate array, and an existing low-resolution ADC chip are used to build a third-order 16-bit oversampling delta-sigma modulator. This modulator is equipped with a digital decimation filter, thus facilitating higher resolution and larger dynamic range seismic data acquisition. Experimental results show that, within the 0.1–40 Hz frequency range, the circuit board's dynamic range reaches 158.2 d B, its resolution reaches 25.99 bits, and its linearity error is below 2.5 ppm, which is better than what is achieved by the commercial 24-bit ADC chips ADS1281 and CS5371. This demonstrates that the proposed method may alleviate or even completely resolve the amplitude-limitation problem that so commonly occurs with broadband observation instruments during strong earthquakes.