Pub Date : 2019-04-04DOI: 10.3997/2214-4609.201900045
V. Angelov, C. Purcell, T. Latter, A. Ratcliffe
Summary Building very large scale depth velocity models for imaging and interpretation purposes is a challenging task that pushes the boundaries of software and hardware processing capabilities ( Gabrielli et al., 2016 ). Here we demonstrate a model build over what we believe is one of the largest areas ever published (~35,000 km2), highlighting the application of high-end technology, with an attention to detail and a delivery schedule that just a few years ago would have only been possible on a small scale survey. We also examine how integrating large amounts of carefully selected and pre-processed well and stratigraphic data benefits the model building process.
{"title":"Technology Advances in Constructing High Resolution Velocity and Absorption Models over 35,000km2 in the North Sea","authors":"V. Angelov, C. Purcell, T. Latter, A. Ratcliffe","doi":"10.3997/2214-4609.201900045","DOIUrl":"https://doi.org/10.3997/2214-4609.201900045","url":null,"abstract":"Summary Building very large scale depth velocity models for imaging and interpretation purposes is a challenging task that pushes the boundaries of software and hardware processing capabilities ( Gabrielli et al., 2016 ). Here we demonstrate a model build over what we believe is one of the largest areas ever published (~35,000 km2), highlighting the application of high-end technology, with an attention to detail and a delivery schedule that just a few years ago would have only been possible on a small scale survey. We also examine how integrating large amounts of carefully selected and pre-processed well and stratigraphic data benefits the model building process.","PeriodicalId":350524,"journal":{"name":"Second EAGE/PESGB Workshop on Velocities","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126426190","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 : 2019-04-04DOI: 10.3997/2214-4609.201900038
M. Gineste, J. Eidsvik, Y. Zheng
Summary The seismic inverse problem is considered in a Bayesian framework and uses a sequential filtering approach to invert for elastic parameters. The method employs an iterative ensemble smoother to estimate the subsurface parameters and from the ensemble, an estimation uncertainty can be extracted. The sequential filtering conditions over partitions of the entire data record in order to drive the estimation process in a top-down manner and regularize the inversion process. The method is presented with a synthetic example using seismic shot record for a 1D medium.
{"title":"Seismic Waveform Inversion Using an Iterative Ensemble Kalman Smoother","authors":"M. Gineste, J. Eidsvik, Y. Zheng","doi":"10.3997/2214-4609.201900038","DOIUrl":"https://doi.org/10.3997/2214-4609.201900038","url":null,"abstract":"Summary The seismic inverse problem is considered in a Bayesian framework and uses a sequential filtering approach to invert for elastic parameters. The method employs an iterative ensemble smoother to estimate the subsurface parameters and from the ensemble, an estimation uncertainty can be extracted. The sequential filtering conditions over partitions of the entire data record in order to drive the estimation process in a top-down manner and regularize the inversion process. The method is presented with a synthetic example using seismic shot record for a 1D medium.","PeriodicalId":350524,"journal":{"name":"Second EAGE/PESGB Workshop on Velocities","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128137818","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 : 2019-04-04DOI: 10.3997/2214-4609.201900056
N. Chemingui, A. Valenciano, T. Martin
Conventional velocity model building (VMB) in complex regimes, such as intra and subsalt data, requires time-consuming manual intervention. It is a process that can produce unreliable models, leading to an increase in uncertainty for subsalt lead evaluation. We demonstrate an application of Full Waveform Inversion (FWI) to refine legacy velocity models generated by conventional VMB. We present our solution on a simultaneous long-offsets (SLO) dataset from the Gulf of Mexico, acquired with dual-sensor streamers, which provided low-frequency rich data. The SLO configuration recorded data with 16 km of offset, enabling both refractions and reflections to update the deeper parts of the velocity model. We employ an FWI velocity gradient that eliminates the migration isochrones. This provides support for the intra and subsalt model updates by removing the reflectivity imprint from the updated models. The FWI application successfully refined the geometry of the salt bodies including the base salt and the intrasalt enclosures. RTM images show a marked uplift, particularly for both the salt flanks and subsalt reflectors.
{"title":"Deep Updates - Challenges and Solutions for FWI","authors":"N. Chemingui, A. Valenciano, T. Martin","doi":"10.3997/2214-4609.201900056","DOIUrl":"https://doi.org/10.3997/2214-4609.201900056","url":null,"abstract":"Conventional velocity model building (VMB) in complex regimes, such as intra and subsalt data, requires time-consuming manual intervention. It is a process that can produce unreliable models, leading to an increase in uncertainty for subsalt lead evaluation. We demonstrate an application of Full Waveform Inversion (FWI) to refine legacy velocity models generated by conventional VMB. We present our solution on a simultaneous long-offsets (SLO) dataset from the Gulf of Mexico, acquired with dual-sensor streamers, which provided low-frequency rich data. The SLO configuration recorded data with 16 km of offset, enabling both refractions and reflections to update the deeper parts of the velocity model. We employ an FWI velocity gradient that eliminates the migration isochrones. This provides support for the intra and subsalt model updates by removing the reflectivity imprint from the updated models. The FWI application successfully refined the geometry of the salt bodies including the base salt and the intrasalt enclosures. RTM images show a marked uplift, particularly for both the salt flanks and subsalt reflectors.","PeriodicalId":350524,"journal":{"name":"Second EAGE/PESGB Workshop on Velocities","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122657106","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 : 2019-04-04DOI: 10.3997/2214-4609.201900041
L. Diekmann, B. Schwarz, A. Bauer, D. Gajewski
Summary We propose a workflow for velocity model building based on passive seismic data. The under-lying tomographic inversion makes use of the slopes and curvatures of the recorded wavefield and inverts for velocities, source locations and source excitation times simultaneously. Owing to the intrinsic robustness of coherence analysis, which constitutes the initial step of the method, our approach can deal with high levels of noise and sparse data. It does not require detailed a priori information and represents an adequate tool for retrieving an initial estimate of the over-burden velocities and, considering the passive events, the respective source locations.
{"title":"Wavefront Tomography for Passive Seismic Data","authors":"L. Diekmann, B. Schwarz, A. Bauer, D. Gajewski","doi":"10.3997/2214-4609.201900041","DOIUrl":"https://doi.org/10.3997/2214-4609.201900041","url":null,"abstract":"Summary We propose a workflow for velocity model building based on passive seismic data. The under-lying tomographic inversion makes use of the slopes and curvatures of the recorded wavefield and inverts for velocities, source locations and source excitation times simultaneously. Owing to the intrinsic robustness of coherence analysis, which constitutes the initial step of the method, our approach can deal with high levels of noise and sparse data. It does not require detailed a priori information and represents an adequate tool for retrieving an initial estimate of the over-burden velocities and, considering the passive events, the respective source locations.","PeriodicalId":350524,"journal":{"name":"Second EAGE/PESGB Workshop on Velocities","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123692634","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 : 2019-04-04DOI: 10.3997/2214-4609.201900031
S. Chen, A. Davydov, S. Roy
Summary Full Wave Inversion (FWI) has been successfully applied in the oil and gas industry as a high-end tool for high-resolution and complex model building. Conventional FWI commonly utilizes diving and refracted waves to update the low-wavenumber background components of the model, however, the update is usually depth limited by the acquisition offset. We present a case study from the Black Sea Khan Kubrat area to demonstrate an optimized workflow using conventional FWI followed by reflection-based FWI to update the velocity model from shallow to deep.
{"title":"Using Full-waveform Inversion to Build Model from Shallow to Deep: A Case Study in Black Sea","authors":"S. Chen, A. Davydov, S. Roy","doi":"10.3997/2214-4609.201900031","DOIUrl":"https://doi.org/10.3997/2214-4609.201900031","url":null,"abstract":"Summary Full Wave Inversion (FWI) has been successfully applied in the oil and gas industry as a high-end tool for high-resolution and complex model building. Conventional FWI commonly utilizes diving and refracted waves to update the low-wavenumber background components of the model, however, the update is usually depth limited by the acquisition offset. We present a case study from the Black Sea Khan Kubrat area to demonstrate an optimized workflow using conventional FWI followed by reflection-based FWI to update the velocity model from shallow to deep.","PeriodicalId":350524,"journal":{"name":"Second EAGE/PESGB Workshop on Velocities","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121416116","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 : 2019-04-04DOI: 10.3997/2214-4609.201900030
S. Stokes, D. Manns, M. Romanenko, B. Kjølhamar, R. Myklebust, E. Henden
Summary The Senja Ridge is a structurally complex high located in the western margin of the Norwegian Barents Sea. A two stage velocity model building approach is implemented, utilising diving wave FWI and high resolution image guided tomography. Shallow gas clouds and shallow channels are resolved with the FWI updates, deeper structures including basement horsts within the Senja Ridge and the flanks of salt diapirs are solved with the tomographic updates.
{"title":"A FWI Velocity Model Building Workflow across the Senja Ridge in the Norwegian Barents Sea","authors":"S. Stokes, D. Manns, M. Romanenko, B. Kjølhamar, R. Myklebust, E. Henden","doi":"10.3997/2214-4609.201900030","DOIUrl":"https://doi.org/10.3997/2214-4609.201900030","url":null,"abstract":"Summary The Senja Ridge is a structurally complex high located in the western margin of the Norwegian Barents Sea. A two stage velocity model building approach is implemented, utilising diving wave FWI and high resolution image guided tomography. Shallow gas clouds and shallow channels are resolved with the FWI updates, deeper structures including basement horsts within the Senja Ridge and the flanks of salt diapirs are solved with the tomographic updates.","PeriodicalId":350524,"journal":{"name":"Second EAGE/PESGB Workshop on Velocities","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124004615","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 : 2019-04-04DOI: 10.3997/2214-4609.201900033
G. Hilburn, J. Mao, J. Sheng, S. Baldock, M. Hart
Summary Geologically reasonable, data-driven velocity model building is a critical process for seismic imaging, particularly when the velocity is strongly heterogeneous within a layer or structure. When such features are prominent in the shallow, disruption of the signal may propagate through a significant portion of the image. A hybrid tomography-FWI workflow incorporating image-guided tomography and phase-only reflection full-waveform inversion is proposed as a method for generating robust and detailed model updates in these situations. Application to a narrow azimuth streamer survey demonstrates the effectiveness of the method in yielding detailed model updates and simplified geological structures in the final image.
{"title":"Hybrid Tomography and Full Waveform Inversion Velocity Model Updating for Shallow Velocity Anomalies","authors":"G. Hilburn, J. Mao, J. Sheng, S. Baldock, M. Hart","doi":"10.3997/2214-4609.201900033","DOIUrl":"https://doi.org/10.3997/2214-4609.201900033","url":null,"abstract":"Summary Geologically reasonable, data-driven velocity model building is a critical process for seismic imaging, particularly when the velocity is strongly heterogeneous within a layer or structure. When such features are prominent in the shallow, disruption of the signal may propagate through a significant portion of the image. A hybrid tomography-FWI workflow incorporating image-guided tomography and phase-only reflection full-waveform inversion is proposed as a method for generating robust and detailed model updates in these situations. Application to a narrow azimuth streamer survey demonstrates the effectiveness of the method in yielding detailed model updates and simplified geological structures in the final image.","PeriodicalId":350524,"journal":{"name":"Second EAGE/PESGB Workshop on Velocities","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114593520","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 : 2019-04-04DOI: 10.3997/2214-4609.201900047
R. Plessix
Summary In its standard least-square formulation, full waveform inversion aims at matching both the phases and the amplitudes of the recorded events. The dynamics of the seismic waves, especially of the reflection waves are of elastic nature. Moreover, earth parameter variations inside the first Fresnel zone induce interference patterns that may also be of elastic nature according to the diffraction theory. Since the Fresnel zone is inversely proportional to the square root of frequency, these interferences occur more at low frequencies. To account for this phenomenon, we may consider a more precise physics to describe the diffraction effects. During this presentation, I shall discuss multi-parameter inversion under the viscous acoustic and the elastic assumption to discuss the need to account for more precise physics.
{"title":"Should We Move towards Multi-parameter Elastic Inversions?","authors":"R. Plessix","doi":"10.3997/2214-4609.201900047","DOIUrl":"https://doi.org/10.3997/2214-4609.201900047","url":null,"abstract":"Summary In its standard least-square formulation, full waveform inversion aims at matching both the phases and the amplitudes of the recorded events. The dynamics of the seismic waves, especially of the reflection waves are of elastic nature. Moreover, earth parameter variations inside the first Fresnel zone induce interference patterns that may also be of elastic nature according to the diffraction theory. Since the Fresnel zone is inversely proportional to the square root of frequency, these interferences occur more at low frequencies. To account for this phenomenon, we may consider a more precise physics to describe the diffraction effects. During this presentation, I shall discuss multi-parameter inversion under the viscous acoustic and the elastic assumption to discuss the need to account for more precise physics.","PeriodicalId":350524,"journal":{"name":"Second EAGE/PESGB Workshop on Velocities","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124796570","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 : 2019-04-04DOI: 10.3997/2214-4609.201900044
T. Barling, R. Bachrach, C. Leone, S. Chen
Summary Constraints can be imposed to a velocity model by rock physics modelling to capture key geological processes that shaped the present-day response of the subsurface. Lithology-dependent compaction trends can provide useful information on the expected range of velocities at different depths. The ability to model those compaction trends and to jointly estimate lithologies and velocities from seismic amplitudes with fully data-driven inversion approaches means that seismic reservoir characterization workflows can be incorporated in the earth model building process to improve imaging velocities. In this North Sea example, we demonstrate how litho-elastic inversion results, which use reflection amplitude- and lithology-driven compaction modelling, are used to update and provide initial low-frequency P- and S-wave velocity models for seismic imaging. The results revealed uplift in the P- and S-wave velocity model, stacked images, and gathers when the low-wavenumber velocities from joint litho-elastic inversion are incorporated into the earth model building workflow. The improvements of the earth model building workflow increase the likelihood of faster and more accurate convergence of subsequent tomographic iterations.
{"title":"Using Joint Lithology-Elastic Inversion to Enhance Earth Model Building Workflows","authors":"T. Barling, R. Bachrach, C. Leone, S. Chen","doi":"10.3997/2214-4609.201900044","DOIUrl":"https://doi.org/10.3997/2214-4609.201900044","url":null,"abstract":"Summary Constraints can be imposed to a velocity model by rock physics modelling to capture key geological processes that shaped the present-day response of the subsurface. Lithology-dependent compaction trends can provide useful information on the expected range of velocities at different depths. The ability to model those compaction trends and to jointly estimate lithologies and velocities from seismic amplitudes with fully data-driven inversion approaches means that seismic reservoir characterization workflows can be incorporated in the earth model building process to improve imaging velocities. In this North Sea example, we demonstrate how litho-elastic inversion results, which use reflection amplitude- and lithology-driven compaction modelling, are used to update and provide initial low-frequency P- and S-wave velocity models for seismic imaging. The results revealed uplift in the P- and S-wave velocity model, stacked images, and gathers when the low-wavenumber velocities from joint litho-elastic inversion are incorporated into the earth model building workflow. The improvements of the earth model building workflow increase the likelihood of faster and more accurate convergence of subsequent tomographic iterations.","PeriodicalId":350524,"journal":{"name":"Second EAGE/PESGB Workshop on Velocities","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129328068","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 : 2019-04-04DOI: 10.3997/2214-4609.201900055
O. Litvyakova, A. Sakharov, A. Welbon, A. Bodrov, A. Korolev, B. Esinov, Ø. Bø
Two datasets with different marine acquisition parameters are available for this project – a conventional PGS survey from 2007 and a Geo-streamer PGS survey from 2015. They both have different shooting directions. Both surveys have been previously pre-processed using a conventional processing sequence. Although the quality of the surveys is good, improvement would be expected from the combination of the two surveys.
{"title":"Dual-azimuth Depth Imaging of Marine Surveys over Fenja Field","authors":"O. Litvyakova, A. Sakharov, A. Welbon, A. Bodrov, A. Korolev, B. Esinov, Ø. Bø","doi":"10.3997/2214-4609.201900055","DOIUrl":"https://doi.org/10.3997/2214-4609.201900055","url":null,"abstract":"Two datasets with different marine acquisition parameters are available for this project – a conventional PGS survey from 2007 and a Geo-streamer PGS survey from 2015. They both have different shooting directions. Both surveys have been previously pre-processed using a conventional processing sequence. Although the quality of the surveys is good, improvement would be expected from the combination of the two surveys.","PeriodicalId":350524,"journal":{"name":"Second EAGE/PESGB Workshop on Velocities","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129368154","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}
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