Pub Date : 2021-10-18DOI: 10.3997/2214-4609.202113278
Y. Yang, J. Ramos-Martínez, D. Whitmore, G. Huang, N. Chemingui
Summary We present an iterative non-linear inversion method to simultaneously estimate both velocity and reflectivity. The core of the inversion workflow is a full acoustic wavefield modeling relation parameterized in terms of velocity and vector reflectivity. A key aspect is the separation of the low- and high-wavenumber components of the gradient based on inverse scattering theory, enabling the sensitivity kernels to update the velocity and the vector reflectivity, respectively. The estimation problem is formulated as a multi-parameter adjoint-state inversion where the trade-off between velocity and reflectivity is minimized through scale separation. Our approach is equivalent to performing Full Waveform Inversion (FWI) and Least-Squares Reverse Time Migration (LSRTM) in a single framework using the full wavefield. The output of the inversion is a detailed velocity model together with an accurate estimate of the earth reflectivity with compensation for incomplete acquisition, poor illumination, and multiple crosstalk. The new approach reduces the turnaround time of imaging projects by combining velocity model building (FWI) and imaging (LSRTM) into a single inversion process with minimal data pre-processing.
{"title":"Simultaneous velocity and reflectivity inversion: FWI + LSRTM","authors":"Y. Yang, J. Ramos-Martínez, D. Whitmore, G. Huang, N. Chemingui","doi":"10.3997/2214-4609.202113278","DOIUrl":"https://doi.org/10.3997/2214-4609.202113278","url":null,"abstract":"Summary We present an iterative non-linear inversion method to simultaneously estimate both velocity and reflectivity. The core of the inversion workflow is a full acoustic wavefield modeling relation parameterized in terms of velocity and vector reflectivity. A key aspect is the separation of the low- and high-wavenumber components of the gradient based on inverse scattering theory, enabling the sensitivity kernels to update the velocity and the vector reflectivity, respectively. The estimation problem is formulated as a multi-parameter adjoint-state inversion where the trade-off between velocity and reflectivity is minimized through scale separation. Our approach is equivalent to performing Full Waveform Inversion (FWI) and Least-Squares Reverse Time Migration (LSRTM) in a single framework using the full wavefield. The output of the inversion is a detailed velocity model together with an accurate estimate of the earth reflectivity with compensation for incomplete acquisition, poor illumination, and multiple crosstalk. The new approach reduces the turnaround time of imaging projects by combining velocity model building (FWI) and imaging (LSRTM) into a single inversion process with minimal data pre-processing.","PeriodicalId":265130,"journal":{"name":"82nd EAGE Annual Conference & Exhibition","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128728484","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 : 2021-10-18DOI: 10.3997/2214-4609.202113234
M. Shahnazi, H. Nezamoleslami, E. Baniasadi, H. Daneshvar, A. R. Nayeh, M. Etminan, B. Heidari
Summary Detecting shallow geohazard risk is one of the critical challenging issues during well drilling for gas fields development. 3D conventional seismic surveys typically contain information from deep parts, since they are designed for deep reservoir targets. In current study, several 2D high resolution seismic data with dense line spacing were acquired for shallow geohazard evaluation over a shallow marine gas field, offshore Iran. Such data is beneficial in terms of available near offset information which are necessary for shallow marine hazards evaluations. On the other hand, 2D imaging cannot be accurate to distinguish correct subsurface location of the drilling hazardous features. In this situation, pseudo- 3D migration is an appropriate method to achieve the correct subsurface image with more details relative to 3D conventional seismic. Pseudo-3D cube generation also has some other advantages that can be profitable in seismic data interpretation including: 3D attribute calculation, surface (horizon) attribute estimation, 3D geo-body extraction and accelerating seismic data interpretation procedure.
{"title":"A case study of shallow marine survey for geohazard risk evaluation, offshore Iran","authors":"M. Shahnazi, H. Nezamoleslami, E. Baniasadi, H. Daneshvar, A. R. Nayeh, M. Etminan, B. Heidari","doi":"10.3997/2214-4609.202113234","DOIUrl":"https://doi.org/10.3997/2214-4609.202113234","url":null,"abstract":"Summary Detecting shallow geohazard risk is one of the critical challenging issues during well drilling for gas fields development. 3D conventional seismic surveys typically contain information from deep parts, since they are designed for deep reservoir targets. In current study, several 2D high resolution seismic data with dense line spacing were acquired for shallow geohazard evaluation over a shallow marine gas field, offshore Iran. Such data is beneficial in terms of available near offset information which are necessary for shallow marine hazards evaluations. On the other hand, 2D imaging cannot be accurate to distinguish correct subsurface location of the drilling hazardous features. In this situation, pseudo- 3D migration is an appropriate method to achieve the correct subsurface image with more details relative to 3D conventional seismic. Pseudo-3D cube generation also has some other advantages that can be profitable in seismic data interpretation including: 3D attribute calculation, surface (horizon) attribute estimation, 3D geo-body extraction and accelerating seismic data interpretation procedure.","PeriodicalId":265130,"journal":{"name":"82nd EAGE Annual Conference & Exhibition","volume":"93 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124672636","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 : 2021-10-18DOI: 10.3997/2214-4609.202113320
T. Langenkamp, L. Stright, S. Hubbard, B. Romans
Summary Forward seismic reflectivity models can be used to interpret depositional architecture and stratal surfaces. However, such studies often stop short at a qualitative assessment of the link between underlying depositional architecture and seismic resolvability, lacking a quantitative assessment. This study addresses this gap with a direct quantitative comparison of 3-dimensional facies architecture predicted from seismic with a “ground truth” to quantify heterogeneity facies associations and architecture preserved in inverted seismic data. The primary goal is to quantify how facies architecture information is preserved in and predicted from inverted seismic reflectivity data. The objective is to explore what the variables are that impact correct vs incorrect facies classification. With increasing seismic frequency, channel axis becomes harder to predict while mass transport deposits became easier to predict. Facies in shallow reservoirs are easier to predict than in deep reservoirs. Disorganized channel systems show greater facies predictability than organized systems due to greater AI contrasts. This study highlights what architectural information is preserved in 3-dimensional inverted seismic data, built from outcrop data of a deep-water system, which can aid directly in interpretation, reservoir prediction, and modelling.
{"title":"Quantitatively Evaluating the Preservation of Deep-water Channel Architecture using 3D Synthetic Seismic from Outcrop","authors":"T. Langenkamp, L. Stright, S. Hubbard, B. Romans","doi":"10.3997/2214-4609.202113320","DOIUrl":"https://doi.org/10.3997/2214-4609.202113320","url":null,"abstract":"Summary Forward seismic reflectivity models can be used to interpret depositional architecture and stratal surfaces. However, such studies often stop short at a qualitative assessment of the link between underlying depositional architecture and seismic resolvability, lacking a quantitative assessment. This study addresses this gap with a direct quantitative comparison of 3-dimensional facies architecture predicted from seismic with a “ground truth” to quantify heterogeneity facies associations and architecture preserved in inverted seismic data. The primary goal is to quantify how facies architecture information is preserved in and predicted from inverted seismic reflectivity data. The objective is to explore what the variables are that impact correct vs incorrect facies classification. With increasing seismic frequency, channel axis becomes harder to predict while mass transport deposits became easier to predict. Facies in shallow reservoirs are easier to predict than in deep reservoirs. Disorganized channel systems show greater facies predictability than organized systems due to greater AI contrasts. This study highlights what architectural information is preserved in 3-dimensional inverted seismic data, built from outcrop data of a deep-water system, which can aid directly in interpretation, reservoir prediction, and modelling.","PeriodicalId":265130,"journal":{"name":"82nd EAGE Annual Conference & Exhibition","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124772161","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 : 2021-10-18DOI: 10.3997/2214-4609.202113157
H. Ozasa, J. Takekawa, H. Mikada
Summary We developed a processing method to separate and utilize long-period sea surface reflected waves by applying wavefield extrapolation processing. It would be possible to separate the sea surface reflection waves from the survey data with high accuracy using the pseudo sea surface reflection generated by downward wavefield extrapolation. In addition, it would also be possible to use the separated multiple to enhance the signal-to-noise ratio of the survey result by applying the upward wavefield extrapolation. We applied our method to the survey data obtained by the deep-towable marine seismic vibrator towed at 225 m depth to verify the effectiveness of our method. Our processing method could remove the effect of a long-period sea surface reflection, which has been a problem to realize a seismic survey with a deep-towed seismic source. In addition, our proposed method could use the decoupled reflection waves to enhance the signal strength by considering it as survey data from a mirrored source.
{"title":"Removal of frequency notches in marine seismic data acquired by a deeply towed source","authors":"H. Ozasa, J. Takekawa, H. Mikada","doi":"10.3997/2214-4609.202113157","DOIUrl":"https://doi.org/10.3997/2214-4609.202113157","url":null,"abstract":"Summary We developed a processing method to separate and utilize long-period sea surface reflected waves by applying wavefield extrapolation processing. It would be possible to separate the sea surface reflection waves from the survey data with high accuracy using the pseudo sea surface reflection generated by downward wavefield extrapolation. In addition, it would also be possible to use the separated multiple to enhance the signal-to-noise ratio of the survey result by applying the upward wavefield extrapolation. We applied our method to the survey data obtained by the deep-towable marine seismic vibrator towed at 225 m depth to verify the effectiveness of our method. Our processing method could remove the effect of a long-period sea surface reflection, which has been a problem to realize a seismic survey with a deep-towed seismic source. In addition, our proposed method could use the decoupled reflection waves to enhance the signal strength by considering it as survey data from a mirrored source.","PeriodicalId":265130,"journal":{"name":"82nd EAGE Annual Conference & Exhibition","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130390247","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 : 2021-10-18DOI: 10.3997/2214-4609.202113086
Y. Luo, Y. Chen, P. Chen, J. Cui, L. Li, Z. Wan, H. Xue
Summary Due to the inherent band-limited character of seismic data, conventional deterministic inversion methods cannot identify thin reservoir information beyond the seismic resolution. Besides, traditional Monte Carlo-based stochastic inversion requires a large number of iterative sampling, which is computational inefficiency. Hence, we develop a joint Bayesian stochastic AVA inversion method based on the linear inverse Gaussian theory and geostatistics. It directly integrates seismic data, well-log data and geostatistical information into a unified expression under the Bayesian framework, and uses the sequential Gaussian simulation to efficiently sample the joint posterior probability density function. The synthetic data example verifies the advantages of better consistency at the locations of har data and the reduction of the inversion uncertainty compared to the classical Bayesian linearized AVA inversion. The field data example shows the validity of this method in the quantitative estimation of facies.
{"title":"Joint Bayesian stochastic AVA inversion of well-log and seismic data for facies estimation","authors":"Y. Luo, Y. Chen, P. Chen, J. Cui, L. Li, Z. Wan, H. Xue","doi":"10.3997/2214-4609.202113086","DOIUrl":"https://doi.org/10.3997/2214-4609.202113086","url":null,"abstract":"Summary Due to the inherent band-limited character of seismic data, conventional deterministic inversion methods cannot identify thin reservoir information beyond the seismic resolution. Besides, traditional Monte Carlo-based stochastic inversion requires a large number of iterative sampling, which is computational inefficiency. Hence, we develop a joint Bayesian stochastic AVA inversion method based on the linear inverse Gaussian theory and geostatistics. It directly integrates seismic data, well-log data and geostatistical information into a unified expression under the Bayesian framework, and uses the sequential Gaussian simulation to efficiently sample the joint posterior probability density function. The synthetic data example verifies the advantages of better consistency at the locations of har data and the reduction of the inversion uncertainty compared to the classical Bayesian linearized AVA inversion. The field data example shows the validity of this method in the quantitative estimation of facies.","PeriodicalId":265130,"journal":{"name":"82nd EAGE Annual Conference & Exhibition","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123660468","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 : 2021-10-18DOI: 10.3997/2214-4609.202113091
M. Irakarama, M. Thierry-Coudon, M. Zakari, P. Anquez, G. Caumon
Summary We introduce a method for implicit 3D geological structural modeling based on finite elements. Implicit modeling on tetrahedral meshes has relied on the constant-gradient regularization operator, since this operator was introduced to the geoscience community over a decade ago. We show that this operator is a finite element discretization of the Laplacian operator in disguise. We then propose a finite element discretization of the Hessian energy, leading to a more appropriate regularization operator for minimizing the curvature of the implicit function on tetrahedral meshes. Special attention is needed at model boundary as boundary conditions are unknown.
{"title":"Implicit 3D Subsurface Structural Modeling by Finite Elements","authors":"M. Irakarama, M. Thierry-Coudon, M. Zakari, P. Anquez, G. Caumon","doi":"10.3997/2214-4609.202113091","DOIUrl":"https://doi.org/10.3997/2214-4609.202113091","url":null,"abstract":"Summary We introduce a method for implicit 3D geological structural modeling based on finite elements. Implicit modeling on tetrahedral meshes has relied on the constant-gradient regularization operator, since this operator was introduced to the geoscience community over a decade ago. We show that this operator is a finite element discretization of the Laplacian operator in disguise. We then propose a finite element discretization of the Hessian energy, leading to a more appropriate regularization operator for minimizing the curvature of the implicit function on tetrahedral meshes. Special attention is needed at model boundary as boundary conditions are unknown.","PeriodicalId":265130,"journal":{"name":"82nd EAGE Annual Conference & Exhibition","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124295346","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 : 2021-10-18DOI: 10.3997/2214-4609.202113281
C. Ciuperca, C. Bădulescu, M. Erlström, E. Mats, A. Hammar
Summary A holistic formation evaluation approach to characterizing the naturally open fractures zones explained the basement negative temperature anomaly occurrence. For this purpose, using measurements of high resolution dual slim imager, acoustic cross-dipole, density, photoelectric factor, spectral gamma ray and temperature, few formation evaluation techniques were applied, such as structural facies identification, fracture aperture calculation, sonic anisotropy, brittleness index magnitude and polarity, Stoneley fracture identification, which, coupled with mudlogging data offered a conprehensive understanding of the naturally occurring fractured zones over the thermal conductivity anomaly. The presence of fractured facies identified on borehole images, decrease of density values, the occurrence of sonic anisotropy, changes in the brittleness index polarity, increase of the fracture density, increase of the fracture aperture and the presence of Stoneley reflection chevrons were used as arguments of water influx through conjugated open natural fracture system which generated the negative thermal anomaly.
{"title":"An Integrated Formation Evaluation Approach Evaluated the Basement Temperature Anomaly","authors":"C. Ciuperca, C. Bădulescu, M. Erlström, E. Mats, A. Hammar","doi":"10.3997/2214-4609.202113281","DOIUrl":"https://doi.org/10.3997/2214-4609.202113281","url":null,"abstract":"Summary A holistic formation evaluation approach to characterizing the naturally open fractures zones explained the basement negative temperature anomaly occurrence. For this purpose, using measurements of high resolution dual slim imager, acoustic cross-dipole, density, photoelectric factor, spectral gamma ray and temperature, few formation evaluation techniques were applied, such as structural facies identification, fracture aperture calculation, sonic anisotropy, brittleness index magnitude and polarity, Stoneley fracture identification, which, coupled with mudlogging data offered a conprehensive understanding of the naturally occurring fractured zones over the thermal conductivity anomaly. The presence of fractured facies identified on borehole images, decrease of density values, the occurrence of sonic anisotropy, changes in the brittleness index polarity, increase of the fracture density, increase of the fracture aperture and the presence of Stoneley reflection chevrons were used as arguments of water influx through conjugated open natural fracture system which generated the negative thermal anomaly.","PeriodicalId":265130,"journal":{"name":"82nd EAGE Annual Conference & Exhibition","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126448150","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 : 2021-10-18DOI: 10.3997/2214-4609.202113135
Q. Wei, X. Li
Summary Seismic data acquisition is the foundation of seismic exploration. When sampling at offset is too coarse during the acquisition, spatial aliasing will appear, affecting the accuracy of subsequent processing. In order to remove the spatial aliasing, the receiver spacing should be reduced, which can be achieved by interpolating one trace between every two traces. And the seismic data with spatial aliasing can be seen as regular missing data. Conditional generative adversarial networks (cGANs) are deep-learning models learning to generate new data with the same statistics as the training dataset based on the given input. In this abstract, a cGAN is designed for application to interpolation. To train the network, one geological model is created to synthesize seismic data. We use a synthetic dataset based on a new geological model and a field dataset to assess the performance of the trained network qualitatively and quantitatively. The test results indicate that the spatial aliasing can be removed effectively using the cGAN interpolation method.
{"title":"Generative Adversarial Network for Seismic Data Interpolation","authors":"Q. Wei, X. Li","doi":"10.3997/2214-4609.202113135","DOIUrl":"https://doi.org/10.3997/2214-4609.202113135","url":null,"abstract":"Summary Seismic data acquisition is the foundation of seismic exploration. When sampling at offset is too coarse during the acquisition, spatial aliasing will appear, affecting the accuracy of subsequent processing. In order to remove the spatial aliasing, the receiver spacing should be reduced, which can be achieved by interpolating one trace between every two traces. And the seismic data with spatial aliasing can be seen as regular missing data. Conditional generative adversarial networks (cGANs) are deep-learning models learning to generate new data with the same statistics as the training dataset based on the given input. In this abstract, a cGAN is designed for application to interpolation. To train the network, one geological model is created to synthesize seismic data. We use a synthetic dataset based on a new geological model and a field dataset to assess the performance of the trained network qualitatively and quantitatively. The test results indicate that the spatial aliasing can be removed effectively using the cGAN interpolation method.","PeriodicalId":265130,"journal":{"name":"82nd EAGE Annual Conference & Exhibition","volume":"136 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115882820","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 : 2021-10-18DOI: 10.3997/2214-4609.202011725
A. Piskarev, A. Atakov, M. Sergeev, O. Smirnov
Summary The new airborne geophysical survey allowed to obtain more detailed data on gravity and magnetic anomalies in the northwestern area of the East Siberian Sea. The basement relief was modelled due to correlation of inversion of magnetic and gravity anomalies with the basement depth according to the seismic data along the seismic profiles. The position of main tectonic boundaries – Vilkitsky Basin in the north, North Chukchi Basin in the east, and Zhokhov Basin in the south – was outlined in accordance with the features of the basement relief. Ten graben-like depressions were detected in the eastern part of De Long Rise. Combine interpretation of the magnetic, gravity, and seismic data allowed to clarify the structure of the studied area and to select the areas prospective for hydrocarbons.
{"title":"Sediment Cover Structure in the East Siberian Sea Shelf–Podvodnikov Basin Transition Zone (Arctic Ocean)","authors":"A. Piskarev, A. Atakov, M. Sergeev, O. Smirnov","doi":"10.3997/2214-4609.202011725","DOIUrl":"https://doi.org/10.3997/2214-4609.202011725","url":null,"abstract":"Summary The new airborne geophysical survey allowed to obtain more detailed data on gravity and magnetic anomalies in the northwestern area of the East Siberian Sea. The basement relief was modelled due to correlation of inversion of magnetic and gravity anomalies with the basement depth according to the seismic data along the seismic profiles. The position of main tectonic boundaries – Vilkitsky Basin in the north, North Chukchi Basin in the east, and Zhokhov Basin in the south – was outlined in accordance with the features of the basement relief. Ten graben-like depressions were detected in the eastern part of De Long Rise. Combine interpretation of the magnetic, gravity, and seismic data allowed to clarify the structure of the studied area and to select the areas prospective for hydrocarbons.","PeriodicalId":265130,"journal":{"name":"82nd EAGE Annual Conference & Exhibition","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130157182","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 : 2021-10-18DOI: 10.3997/2214-4609.202010238
A. Belova, Y. Davydenko, D. Gurevich, A. Bashkeev, S. Bukhalov, P. Veeken
Summary Geoelectric techniques are applied to identify geobodies in the shallow subsurface (<1km) that correspond to commercial ore deposits (copper-molybdene) in Kazakhstan. A combined CSEM and Induced Polarisation method is chosen to delineate anomalies in the underground. Resistivity and polarisation effects prove diagnostic. The workflow comprises steps like: EM acquisition, quality control and data preconditioning, inversion, interpretation and Principle Component Analysis. Inversion processing is done via a finite elements method solving the Cole-Cole formula simulating Maxwell’s equations. 1D inversion results serve as input for the 3D inversion. Principle Component Analysis (n-dimensional clustering and distance weighting) and computation of composite geoelectric parameters enhance the discrimination power. EM anomalies are circular (hydrothermal injection feature) and/or elongate in shape. Fracture zones and faults provide conduits/barriers and govern hydrothermal processes. Faulting in part controls the outline of the segmented IP anomalies. Three shallow well locations were proposed based on the EMS-IP data. Two of these boreholes demonstrate elevated polarisation phenomena: copper-molybdene metal ore in MN17 and pyrite enrichment in MN16. The mapped geobodies based on EM anomalies give complementary information on volume and distribution of the mineral resources. EMS-IP is a cost-effective investigation tool that deserves more attention in geoscience projects.
{"title":"Mineral Prospecting for Copper-Molybdene Ores in Northern Kazakhstan Using Electromagnetic Sensing and Induced Polarization Technology (EMS-IP)","authors":"A. Belova, Y. Davydenko, D. Gurevich, A. Bashkeev, S. Bukhalov, P. Veeken","doi":"10.3997/2214-4609.202010238","DOIUrl":"https://doi.org/10.3997/2214-4609.202010238","url":null,"abstract":"Summary Geoelectric techniques are applied to identify geobodies in the shallow subsurface (<1km) that correspond to commercial ore deposits (copper-molybdene) in Kazakhstan. A combined CSEM and Induced Polarisation method is chosen to delineate anomalies in the underground. Resistivity and polarisation effects prove diagnostic. The workflow comprises steps like: EM acquisition, quality control and data preconditioning, inversion, interpretation and Principle Component Analysis. Inversion processing is done via a finite elements method solving the Cole-Cole formula simulating Maxwell’s equations. 1D inversion results serve as input for the 3D inversion. Principle Component Analysis (n-dimensional clustering and distance weighting) and computation of composite geoelectric parameters enhance the discrimination power. EM anomalies are circular (hydrothermal injection feature) and/or elongate in shape. Fracture zones and faults provide conduits/barriers and govern hydrothermal processes. Faulting in part controls the outline of the segmented IP anomalies. Three shallow well locations were proposed based on the EMS-IP data. Two of these boreholes demonstrate elevated polarisation phenomena: copper-molybdene metal ore in MN17 and pyrite enrichment in MN16. The mapped geobodies based on EM anomalies give complementary information on volume and distribution of the mineral resources. EMS-IP is a cost-effective investigation tool that deserves more attention in geoscience projects.","PeriodicalId":265130,"journal":{"name":"82nd EAGE Annual Conference & Exhibition","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130248510","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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