Seismic exploration in the mountainous areas of western Chinese is extremely difficult because of the complexity of the surface and subsurface, which results in shooting difficulties, seismic data with low signal-to-n...Seismic exploration in the mountainous areas of western Chinese is extremely difficult because of the complexity of the surface and subsurface, which results in shooting difficulties, seismic data with low signal-to-noise ratio, and strong interference. The complexity of the subsurface structure leads to strong scattering of the refl ection points; thus, the curved-line acquisition method has been used. However, the actual subsurface structural characteristics have been rarely considered. We propose a design method for irregular acquisition based on common refl ection points（CRP） to avoid difficult-to-shoot areas, while considering the structural characteristics and CRP positions and optimizing the surfacereceiving line position. We arrange the positions of the receiving points to ensure as little dispersion of subsurface CRP as possible to improve the signal-to-noise ratio of the seismic data. We verify the applicability of the method using actual data from a site in Sichuan Basin. The proposed method apparently solves the problem of seismic data acquisition and facilitates seismic exploration in structurally complex areas.展开更多
Oil and gas seismic exploration have to adopt irregular seismic acquisition due to the increasingly complex exploration conditions to adapt to complex geological conditions and environments.However,the irregular seism...Oil and gas seismic exploration have to adopt irregular seismic acquisition due to the increasingly complex exploration conditions to adapt to complex geological conditions and environments.However,the irregular seismic acquisition is accompanied by the lack of acquisition data,which requires high-precision regularization.The sparse signal feature in the transform domain in compressed sensing theory is used in this paper to recover the missing signal,involving sparse transform base optimization and threshold modeling.First,this paper analyzes and compares the effects of six sparse transformation bases on the reconstruction accuracy and efficiency of irregular seismic data and establishes the quantitative relationship between sparse transformation and reconstruction accuracy and efficiency.Second,an adaptive threshold modeling method based on sparse coefficient is provided to improve the reconstruction accuracy.Test results show that the method has good adaptability to different seismic data and sparse transform bases.The f-x domain reconstruction method of effective frequency samples is studied to address the problem of low computational efficiency.The parallel computing strategy of curvelet transform combined with OpenMP is further proposed,which substantially improves the computational efficiency under the premise of ensuring the reconstruction accuracy.Finally,the actual acquisition data are used to verify the proposed method.The results indicate that the proposed method strategy can solve the regularization problem of irregular seismic data in production and improve the imaging quality of the target layer economically and efficiently.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 l00/sec by seismometer acquisition from th...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 l00/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 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
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
Aimed at the poor performance of conventional geophones in exploration for deeper and complex targets, we present the principle and theoretical design of a new geophone based on the optical fiber Bragg grating （FBG）...Aimed at the poor performance of conventional geophones in exploration for deeper and complex targets, we present the principle and theoretical design of a new geophone based on the optical fiber Bragg grating （FBG） sensing technology. The important parameters such as response functions are calculated theoretically. Because of the advantages of FBG sensing technology, the new FBG geophone has a high dynamic range of 94dB at （10-200 Hz）. This new generation of geophones will have wide use in seismic prospecting due to its higher sensitivity, lighter weight, and lower cost.展开更多
Reflected wave seismology has the following defects:the acquisition design is based on the assumption of layered media,the signal processing suppresses weak signals such as diffracted wave and scattered wave,and the s...Reflected wave seismology has the following defects:the acquisition design is based on the assumption of layered media,the signal processing suppresses weak signals such as diffracted wave and scattered wave,and the seismic wave band after the image processing is narrow.They limit the full utilization of broadband raw data.The concept of full wave seismic exploration is redefined based on the idea of balanced utilization of reflected wave,diffracted wave and scattered wave information,its characteristics and adaptive conditions are clarified.A set of key technologies suitable for full wave seismic exploration are put forward.During seismic acquisition period,it is necessary to adopt multi geometry,i.e.embed small bin,small offset and small channel interval data in conventional geometry.By discretizing of common midpoint(CMP)gathers,small offset with high coverage,the weak signals such as diffracted wave and scattered wave in the raw seismic data can be enhanced.During seismic processing,the signal and noise in the original seismic data need to be redefined at first.The effective signals of seismic data are enhanced through merging of multi-geometry data.By means of differential application of data with different bin sizes and different arrangement modes,different regimes of seismic waves can be effectively decomposed and imaged separately.During seismic interpretation stage,making the most of the full wave seismic data,and adopting well-seismic calibration on multi-scale and multi-dimension,the seismic attributes in multi-regimes and multi-domains are interpreted to reveal interior information of complex lithology bodies and improve the lateral resolution of non-layered reservoirs.展开更多
基金funded by The National Natural Science Foundation of China(No.41304115)Sichuan Province innovative team of natural gas geology Construction Program(No.13TD0024)Fund for middle-aged core teachers of SWPU
文摘Seismic exploration in the mountainous areas of western Chinese is extremely difficult because of the complexity of the surface and subsurface, which results in shooting difficulties, seismic data with low signal-to-noise ratio, and strong interference. The complexity of the subsurface structure leads to strong scattering of the refl ection points; thus, the curved-line acquisition method has been used. However, the actual subsurface structural characteristics have been rarely considered. We propose a design method for irregular acquisition based on common refl ection points（CRP） to avoid difficult-to-shoot areas, while considering the structural characteristics and CRP positions and optimizing the surfacereceiving line position. We arrange the positions of the receiving points to ensure as little dispersion of subsurface CRP as possible to improve the signal-to-noise ratio of the seismic data. We verify the applicability of the method using actual data from a site in Sichuan Basin. The proposed method apparently solves the problem of seismic data acquisition and facilitates seismic exploration in structurally complex areas.
基金supported by the National Science and Technology Major project(No.2016ZX05024001003)the Innovation Consortium Project of China Petroleum,and the Southwest Petroleum University(No.2020CX010201).
文摘Oil and gas seismic exploration have to adopt irregular seismic acquisition due to the increasingly complex exploration conditions to adapt to complex geological conditions and environments.However,the irregular seismic acquisition is accompanied by the lack of acquisition data,which requires high-precision regularization.The sparse signal feature in the transform domain in compressed sensing theory is used in this paper to recover the missing signal,involving sparse transform base optimization and threshold modeling.First,this paper analyzes and compares the effects of six sparse transformation bases on the reconstruction accuracy and efficiency of irregular seismic data and establishes the quantitative relationship between sparse transformation and reconstruction accuracy and efficiency.Second,an adaptive threshold modeling method based on sparse coefficient is provided to improve the reconstruction accuracy.Test results show that the method has good adaptability to different seismic data and sparse transform bases.The f-x domain reconstruction method of effective frequency samples is studied to address the problem of low computational efficiency.The parallel computing strategy of curvelet transform combined with OpenMP is further proposed,which substantially improves the computational efficiency under the premise of ensuring the reconstruction accuracy.Finally,the actual acquisition data are used to verify the proposed method.The results indicate that the proposed method strategy can solve the regularization problem of irregular seismic data in production and improve the imaging quality of the target layer economically and efficiently.
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 l00/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.
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.
基金sponsored by the National 863 Program(Grant No.2006AA06Z207&2006AA06Z213)the National Natural Science Foundation of China(Grant No.50674098)the National 973 Program(Grant No.2007CB209601)
文摘Aimed at the poor performance of conventional geophones in exploration for deeper and complex targets, we present the principle and theoretical design of a new geophone based on the optical fiber Bragg grating （FBG） sensing technology. The important parameters such as response functions are calculated theoretically. Because of the advantages of FBG sensing technology, the new FBG geophone has a high dynamic range of 94dB at （10-200 Hz）. This new generation of geophones will have wide use in seismic prospecting due to its higher sensitivity, lighter weight, and lower cost.
基金Supported by the Sinopec Ministry of Science and Technology Project(P21038-3)。
文摘Reflected wave seismology has the following defects:the acquisition design is based on the assumption of layered media,the signal processing suppresses weak signals such as diffracted wave and scattered wave,and the seismic wave band after the image processing is narrow.They limit the full utilization of broadband raw data.The concept of full wave seismic exploration is redefined based on the idea of balanced utilization of reflected wave,diffracted wave and scattered wave information,its characteristics and adaptive conditions are clarified.A set of key technologies suitable for full wave seismic exploration are put forward.During seismic acquisition period,it is necessary to adopt multi geometry,i.e.embed small bin,small offset and small channel interval data in conventional geometry.By discretizing of common midpoint(CMP)gathers,small offset with high coverage,the weak signals such as diffracted wave and scattered wave in the raw seismic data can be enhanced.During seismic processing,the signal and noise in the original seismic data need to be redefined at first.The effective signals of seismic data are enhanced through merging of multi-geometry data.By means of differential application of data with different bin sizes and different arrangement modes,different regimes of seismic waves can be effectively decomposed and imaged separately.During seismic interpretation stage,making the most of the full wave seismic data,and adopting well-seismic calibration on multi-scale and multi-dimension,the seismic attributes in multi-regimes and multi-domains are interpreted to reveal interior information of complex lithology bodies and improve the lateral resolution of non-layered reservoirs.
