Pub Date : 2018-08-27DOI: 10.1190/SEGAM2018-2998174.1
Jizhong Yang, Y. Li, A. Cheng, Yuzhu Liu, Liangguo Dong
An accurate migration velocity model is required for reverse time migration (RTM) to correctly predict the kinematics of wave propagation in the subsurface. Leastsquares reverse time migration (LSRTM), which aims to match the amplitudes of the modeled data with the observed data in an iterative inverse procedure, is more sensitive to the accuracy of the migration velocity model. If the migration velocity model contains errors, the final migration images will be defocused and incoherent. As a partial solution, we utilize an LSRTM scheme based on the extended imaging condition, which is called as leastsquares extended RTM (LSERTM). It is well accepted that LSERTM can fit the observed data regardless of the accuracy of the migration velocity model. We further explore this property and find that after stacking the extended migration images along the subsurface offset axis within properly selected ranges, we can obtain an image with better coherency and focusing than the conventional LSRTM. We demonstrate the efficacy of our method with numerical examples on a Salt-like model and the Marmousi model.
{"title":"Least-squares reverse time migration with velocity errors","authors":"Jizhong Yang, Y. Li, A. Cheng, Yuzhu Liu, Liangguo Dong","doi":"10.1190/SEGAM2018-2998174.1","DOIUrl":"https://doi.org/10.1190/SEGAM2018-2998174.1","url":null,"abstract":"An accurate migration velocity model is required for reverse time migration (RTM) to correctly predict the kinematics of wave propagation in the subsurface. Leastsquares reverse time migration (LSRTM), which aims to match the amplitudes of the modeled data with the observed data in an iterative inverse procedure, is more sensitive to the accuracy of the migration velocity model. If the migration velocity model contains errors, the final migration images will be defocused and incoherent. As a partial solution, we utilize an LSRTM scheme based on the extended imaging condition, which is called as leastsquares extended RTM (LSERTM). It is well accepted that LSERTM can fit the observed data regardless of the accuracy of the migration velocity model. We further explore this property and find that after stacking the extended migration images along the subsurface offset axis within properly selected ranges, we can obtain an image with better coherency and focusing than the conventional LSRTM. We demonstrate the efficacy of our method with numerical examples on a Salt-like model and the Marmousi model.","PeriodicalId":158800,"journal":{"name":"SEG Technical Program Expanded Abstracts 2018","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124931763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-27DOI: 10.1190/segam2018-2998590.1
M. V. de Hoop
{"title":"Deep neural-network architectures arising in seismic-inverse problems","authors":"M. V. de Hoop","doi":"10.1190/segam2018-2998590.1","DOIUrl":"https://doi.org/10.1190/segam2018-2998590.1","url":null,"abstract":"","PeriodicalId":158800,"journal":{"name":"SEG Technical Program Expanded Abstracts 2018","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123245202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-27DOI: 10.1190/SEGAM2018-2997247.1
Fuyong Yan, De‐hua Han, Xue-Lian Chen
{"title":"Power mean fluid substitution without mineral properties","authors":"Fuyong Yan, De‐hua Han, Xue-Lian Chen","doi":"10.1190/SEGAM2018-2997247.1","DOIUrl":"https://doi.org/10.1190/SEGAM2018-2997247.1","url":null,"abstract":"","PeriodicalId":158800,"journal":{"name":"SEG Technical Program Expanded Abstracts 2018","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123291797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-27DOI: 10.1190/SEGAM2018-2971221.1
R. Safipour, A. Swidinsky, S. Hölz, M. Jegen
Two marine geophysical methods are tested over a shallowly buried and hydrothermally inactive massive sulfide occurrence at the Palinuro Seamount in the Tyrrhenian Sea. A novel EM configuration consisting of a ship-towed loop transmitter and remote dipole receivers was deployed over the seamount, and electric field transients were successfully recorded by the remote receivers. An SP system consisting of two perpendicular pairs of electrodes towed close to the seafloor was also deployed. Anomalously high electric field strengths were recorded over the zone of known massive sulfide mineralization, demonstrating that the SP method is effective at detecting inactive, buried massive sulfide sites.
{"title":"Electrical and electromagnetic methods in exploring for seafloor massive sulfide deposits","authors":"R. Safipour, A. Swidinsky, S. Hölz, M. Jegen","doi":"10.1190/SEGAM2018-2971221.1","DOIUrl":"https://doi.org/10.1190/SEGAM2018-2971221.1","url":null,"abstract":"Two marine geophysical methods are tested over a shallowly buried and hydrothermally inactive massive sulfide occurrence at the Palinuro Seamount in the Tyrrhenian Sea. A novel EM configuration consisting of a ship-towed loop transmitter and remote dipole receivers was deployed over the seamount, and electric field transients were successfully recorded by the remote receivers. An SP system consisting of two perpendicular pairs of electrodes towed close to the seafloor was also deployed. Anomalously high electric field strengths were recorded over the zone of known massive sulfide mineralization, demonstrating that the SP method is effective at detecting inactive, buried massive sulfide sites.","PeriodicalId":158800,"journal":{"name":"SEG Technical Program Expanded Abstracts 2018","volume":"41 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123457556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-27DOI: 10.1190/SEGAM2018-W12-02.1
F. Day‐Lewis
{"title":"Geophysical Tomography: The Current State of Research, Challenges, and Path Forward","authors":"F. Day‐Lewis","doi":"10.1190/SEGAM2018-W12-02.1","DOIUrl":"https://doi.org/10.1190/SEGAM2018-W12-02.1","url":null,"abstract":"","PeriodicalId":158800,"journal":{"name":"SEG Technical Program Expanded Abstracts 2018","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123570952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-27DOI: 10.1190/SEGAM2018-2998538.1
E. Slob, K. Wapenaar, S. Treitel
We derive a fast acoustic inversion method for a piecewise homogeneous horizontally layered medium. The method obtains medium parameters from the reflection response. The method can be implemented to obtain the parameters on either side of a reflector at an arbitrary depth. Three processing steps lead to the inversion result. First, we solve a modified Marchenko type equation to obtain a focusing wavefield. We then apply wavefield continuation across a reflecting boundary to the focusing wavefield and retrieve the reflection coefficient of a reflector as a function of horizontal slowness. Finally, we use the reflection coefficient to obtain the velocities and the ratio of the densities above and below the reflector. Because the two-way traveltime difference of the primary reflection and the one above it becomes known during the process, the thickness of the layer above the reflector is also found. The method can be applied multiple times in different zones, or recursively in a target zone without having to solve more Marchenko type equations. The numerical example illustrates that the method works well on modeled data without the need for a priori model information.
{"title":"Fast nonrecursive 1D inversion by filtering acoustic-reflection data","authors":"E. Slob, K. Wapenaar, S. Treitel","doi":"10.1190/SEGAM2018-2998538.1","DOIUrl":"https://doi.org/10.1190/SEGAM2018-2998538.1","url":null,"abstract":"We derive a fast acoustic inversion method for a piecewise homogeneous horizontally layered medium. The method obtains medium parameters from the reflection response. The method can be implemented to obtain the parameters on either side of a reflector at an arbitrary depth. Three processing steps lead to the inversion result. First, we solve a modified Marchenko type equation to obtain a focusing wavefield. We then apply wavefield continuation across a reflecting boundary to the focusing wavefield and retrieve the reflection coefficient of a reflector as a function of horizontal slowness. Finally, we use the reflection coefficient to obtain the velocities and the ratio of the densities above and below the reflector. Because the two-way traveltime difference of the primary reflection and the one above it becomes known during the process, the thickness of the layer above the reflector is also found. The method can be applied multiple times in different zones, or recursively in a target zone without having to solve more Marchenko type equations. The numerical example illustrates that the method works well on modeled data without the need for a priori model information.","PeriodicalId":158800,"journal":{"name":"SEG Technical Program Expanded Abstracts 2018","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123791599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-27DOI: 10.1190/SEGAM2018-2990944.1
O. Michel, I. Tsvankin
3D anisotropic waveform inversion (WI) could provide high-resolution velocity models and improved event locations for microseismic surveys. Here we extend our previously developed 2D WI methodology for microseismic borehole data to 3D anisotropic models. This extension allows us to invert multicomponent data recorded in multiple boreholes and properly account for vertical and lateral heterogeneity. Synthetic examples illustrate the performance of the 3D algorithm for layer-cake and “hydraulically fractured” VTI (transversely isotropic with a vertical symmetry axis) models. In both cases, WI is able to reconstruct parts of the model which are sufficiently illuminated for the employed source-receiver geometry. We also present preliminary results for a data set from a shale play and describe a sequence of processing steps needed to make the seismograms suitable for waveform inversion. After the preprocessing, the observed and modeled direct arrivals exhibit comparable amplitude and phase characteristics and can be used for velocity analysis.
{"title":"3D waveform inversion of microseismic data for VTI media","authors":"O. Michel, I. Tsvankin","doi":"10.1190/SEGAM2018-2990944.1","DOIUrl":"https://doi.org/10.1190/SEGAM2018-2990944.1","url":null,"abstract":"3D anisotropic waveform inversion (WI) could provide high-resolution velocity models and improved event locations for microseismic surveys. Here we extend our previously developed 2D WI methodology for microseismic borehole data to 3D anisotropic models. This extension allows us to invert multicomponent data recorded in multiple boreholes and properly account for vertical and lateral heterogeneity. Synthetic examples illustrate the performance of the 3D algorithm for layer-cake and “hydraulically fractured” VTI (transversely isotropic with a vertical symmetry axis) models. In both cases, WI is able to reconstruct parts of the model which are sufficiently illuminated for the employed source-receiver geometry. We also present preliminary results for a data set from a shale play and describe a sequence of processing steps needed to make the seismograms suitable for waveform inversion. After the preprocessing, the observed and modeled direct arrivals exhibit comparable amplitude and phase characteristics and can be used for velocity analysis.","PeriodicalId":158800,"journal":{"name":"SEG Technical Program Expanded Abstracts 2018","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125288487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-27DOI: 10.1190/SEGAM2018-2988512.1
Yunhuo Zhang, Y. Li, Heng Zhang, T. Ku
We present a case study of passive seismic interferometry in the city of Singapore to investigate the bedrock depth and to determine the optimal acquisition parameters. The ambient-noise field, dominated by urban traffic noise, is recorded passively for seismic interferometry. We demonstrate that the bedrock depth can be determined from ambient seismic noise within an error of 2 m compared with borehole logs. Both synthetic and field data analysis show that the optimal array size for the passive site investigation can be as short as 30 m with 6 vertical geophones, to resolve a 1-D shear wave velocity profile of 50m in depth. Convergence of the cross-correlograms shows that the minimum acquisition time for ambient-noise acquisition is about 15 mins in a typical working day. Success of this case study demonstrates that accurate nearsurface site investigation can be achieved with faster acquisition, fewer receivers and smaller acquisition footprint, all of which improve the efficiency particularly in a highly developed urban environment.
{"title":"Optimized passive seismic interferometry for bedrock detection: A Singapore case study","authors":"Yunhuo Zhang, Y. Li, Heng Zhang, T. Ku","doi":"10.1190/SEGAM2018-2988512.1","DOIUrl":"https://doi.org/10.1190/SEGAM2018-2988512.1","url":null,"abstract":"We present a case study of passive seismic interferometry in the city of Singapore to investigate the bedrock depth and to determine the optimal acquisition parameters. The ambient-noise field, dominated by urban traffic noise, is recorded passively for seismic interferometry. We demonstrate that the bedrock depth can be determined from ambient seismic noise within an error of 2 m compared with borehole logs. Both synthetic and field data analysis show that the optimal array size for the passive site investigation can be as short as 30 m with 6 vertical geophones, to resolve a 1-D shear wave velocity profile of 50m in depth. Convergence of the cross-correlograms shows that the minimum acquisition time for ambient-noise acquisition is about 15 mins in a typical working day. Success of this case study demonstrates that accurate nearsurface site investigation can be achieved with faster acquisition, fewer receivers and smaller acquisition footprint, all of which improve the efficiency particularly in a highly developed urban environment.","PeriodicalId":158800,"journal":{"name":"SEG Technical Program Expanded Abstracts 2018","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126606623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-08-27DOI: 10.1190/SEGAM2018-2996391.1
T. Asch, J. Abraham, J. Cannia
{"title":"A case study on modeling the effect of early times in airborne electromagnetics for higher resolution of the near surface","authors":"T. Asch, J. Abraham, J. Cannia","doi":"10.1190/SEGAM2018-2996391.1","DOIUrl":"https://doi.org/10.1190/SEGAM2018-2996391.1","url":null,"abstract":"","PeriodicalId":158800,"journal":{"name":"SEG Technical Program Expanded Abstracts 2018","volume":"518 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126610583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：