Pub Date : 2025-02-19DOI: 10.1016/j.jappgeo.2025.105660
Anyu Li , Yueming Ye , Xiangyu Zhu , Tao Liu , Huimin Zhang , Yong Xia
Seismic imaging techniques are essential to geophysical exploration and subsurface characterization, with full wave-equation depth migration (FWDM) emerging as a highly effective method for imaging complex geological structures. However, optimizing FWDM requires a deep understanding of the factors influencing its performance to achieve accurate and detailed subsurface images. To address this need, this study presents a systematic approach to refining FWDM by first providing a comprehensive review of the extrapolation equations and imaging mechanisms that form its foundation. We then introduce a series of numerical tests designed to identify and analyze key factors impacting imaging quality, including migration velocity, wave propagation effect, and numerical stability. Based on these findings, we optimize parameters and apply them to two challenging models, allowing us to assess the improvements in imaging clarity and accuracy. This research not only highlights critical factors affecting FWDM but also demonstrates how targeted optimizations can significantly enhance its effectiveness for advanced subsurface imaging applications.
{"title":"Evaluation of factors influencing full wave equation depth migration","authors":"Anyu Li , Yueming Ye , Xiangyu Zhu , Tao Liu , Huimin Zhang , Yong Xia","doi":"10.1016/j.jappgeo.2025.105660","DOIUrl":"10.1016/j.jappgeo.2025.105660","url":null,"abstract":"<div><div>Seismic imaging techniques are essential to geophysical exploration and subsurface characterization, with full wave-equation depth migration (FWDM) emerging as a highly effective method for imaging complex geological structures. However, optimizing FWDM requires a deep understanding of the factors influencing its performance to achieve accurate and detailed subsurface images. To address this need, this study presents a systematic approach to refining FWDM by first providing a comprehensive review of the extrapolation equations and imaging mechanisms that form its foundation. We then introduce a series of numerical tests designed to identify and analyze key factors impacting imaging quality, including migration velocity, wave propagation effect, and numerical stability. Based on these findings, we optimize parameters and apply them to two challenging models, allowing us to assess the improvements in imaging clarity and accuracy. This research not only highlights critical factors affecting FWDM but also demonstrates how targeted optimizations can significantly enhance its effectiveness for advanced subsurface imaging applications.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"235 ","pages":"Article 105660"},"PeriodicalIF":2.2,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143471199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.jappgeo.2025.105659
Derman Dondurur
This study primarily aims to characterize both the shallow and deep structures of shallow gas accumulations and gas seepage by utilizing multi-resolution seismic data. Additionally, it seeks to establish a link between shallow and deep stratigraphy for these gas accumulations and seepage in the outer İzmir Gulf by employing various seismic attributes, such as average energy, relative acoustic impedance, apparent polarity, sweetness, pseudo-relief as well as complex trace attributes. Multi-resolution seismic datsets have been collectively interpreted to obtain deep and shallow architecture of gassy structures in the outer İzmir Gulf. Chirp and sparker seismic data provided information about the shallow gas accumulations as well as seep structures while multi-channel seismic data reveals deep structural and stratigraphic formation and their possible connection with the shallow fluid-flow structures.
Analyses of seismic data and calculated multi-attribute sections indicate that both biogenic and thermogenic gases co-exist in the outer İzmir Gulf. It is concluded that Uzunada Fault Zone acts as a conduit for fluid escape, facilitating gas seeps in the water column above the fault plane. Specifically, the Chirp datasets acquired in 2008 and 2023 indicate that the gas seep along the Uzunada Fault Zone has been active over a period of 15 years along this fault plane.
Depending on the analyses of seismic datasets, observed gas is classified into two groups in terms of its origin: (1) Biogenic gas generated in-situ within the highstand sediments of the Gediz Delta, and (2) thermogenic gas from deeper reservoirs within the Upper Miocene sediments. It is concluded that the gas from the deltaic sediments in the eastern part of the gulf is biogenic in origin formed as a result of the biogenic degradation of organic matter in terrigenous sediments transported by the Gediz River. The possible thermogenic gas accumulations, on the other hand, is originated from the presumed sandy layers interbedded with shale laminations in the Upper Miocene sediments, and migrate along the fault planes through the Plio-Quaternary sediments and accumulate in the shallow sediments.
{"title":"Multi-resolution seismic analysis of a cold seep from İzmir Gulf, Aegean Sea using seismic attributes","authors":"Derman Dondurur","doi":"10.1016/j.jappgeo.2025.105659","DOIUrl":"10.1016/j.jappgeo.2025.105659","url":null,"abstract":"<div><div>This study primarily aims to characterize both the shallow and deep structures of shallow gas accumulations and gas seepage by utilizing multi-resolution seismic data. Additionally, it seeks to establish a link between shallow and deep stratigraphy for these gas accumulations and seepage in the outer İzmir Gulf by employing various seismic attributes, such as average energy, relative acoustic impedance, apparent polarity, sweetness, pseudo-relief as well as complex trace attributes. Multi-resolution seismic datsets have been collectively interpreted to obtain deep and shallow architecture of gassy structures in the outer İzmir Gulf. Chirp and sparker seismic data provided information about the shallow gas accumulations as well as seep structures while multi-channel seismic data reveals deep structural and stratigraphic formation and their possible connection with the shallow fluid-flow structures.</div><div>Analyses of seismic data and calculated multi-attribute sections indicate that both biogenic and thermogenic gases co-exist in the outer İzmir Gulf. It is concluded that Uzunada Fault Zone acts as a conduit for fluid escape, facilitating gas seeps in the water column above the fault plane. Specifically, the Chirp datasets acquired in 2008 and 2023 indicate that the gas seep along the Uzunada Fault Zone has been active over a period of 15 years along this fault plane.</div><div>Depending on the analyses of seismic datasets, observed gas is classified into two groups in terms of its origin: (1) Biogenic gas generated in-situ within the highstand sediments of the Gediz Delta, and (2) thermogenic gas from deeper reservoirs within the Upper Miocene sediments. It is concluded that the gas from the deltaic sediments in the eastern part of the gulf is biogenic in origin formed as a result of the biogenic degradation of organic matter in terrigenous sediments transported by the Gediz River. The possible thermogenic gas accumulations, on the other hand, is originated from the presumed sandy layers interbedded with shale laminations in the Upper Miocene sediments, and migrate along the fault planes through the Plio-Quaternary sediments and accumulate in the shallow sediments.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"235 ","pages":"Article 105659"},"PeriodicalIF":2.2,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The accurate prediction of water saturation in reservoir exploration and development remains a significant challenge, particularly in regions like the Middle East with complex carbonate formations such as the Mishrif Formation. While geophysical logging data is widely utilized for this purpose, however, the complex pore structures render Archie's formula unsuitable, leading to non-Archie phenomenon in rock-electrical experiments. Although the electrical efficiency model has been employed in calculating water saturation in carbonate reservoirs, there has been no prior study incorporating electrical porosity for its refinement. This study enhances the conventional electrical efficiency model by introducing the concept of electrical porosity. The improvement aims to mitigate the impact of isolated mold pores and sparse regions of current density distribution on electrical efficiency, focusing on the Mishrif Formation and quantitatively computing water saturation. Initially, the study area is categorized into three distinct rock-physics types of reservoirs using the Winland R35 method, with respective electrical porosities calculated. Subsequently, these results are integrated with the enhanced electrical efficiency model, and trial calculations are performed using geophysical well-logging data, followed by a comparison with core data. The findings reveal that the improved electrical efficiency model yields an average relative error of only 10.36 % compared to core data, whereas the respective errors for Archie's formula and traditional electrical efficiency models are 17.65 % and 20.92 %, indicating enhanced accuracy with the improved approach. Across different reservoir types, a decrease in electrical porosity proportion is observed with diminishing pore-throat radius. Additionally, the consistency of this trend is validated by nuclear magnetic resonance logging data. Lastly, the necessity of reservoir rock-physics type classification for electrical porosity computation is confirmed. For heterogeneous reservoirs, direct calculation of electrical porosity is infeasible, thus underscoring the essential groundwork of reservoir rock-physics type delineation. This study improves water saturation prediction accuracy and applicability by introducing electrical porosity to refine the conventional electrical efficiency model, holding significant implications for the exploration and development of complex reservoirs.
{"title":"Enhanced water saturation evaluation method using an improved electrical efficiency model: A case study of the Mishrif Formation, Iraq","authors":"Jianhong Guo , Zhansong Zhang , Chaomo Zhang , Qing Zhao , Xiao Tang","doi":"10.1016/j.jappgeo.2025.105656","DOIUrl":"10.1016/j.jappgeo.2025.105656","url":null,"abstract":"<div><div>The accurate prediction of water saturation in reservoir exploration and development remains a significant challenge, particularly in regions like the Middle East with complex carbonate formations such as the Mishrif Formation. While geophysical logging data is widely utilized for this purpose, however, the complex pore structures render Archie's formula unsuitable, leading to non-Archie phenomenon in rock-electrical experiments. Although the electrical efficiency model has been employed in calculating water saturation in carbonate reservoirs, there has been no prior study incorporating electrical porosity for its refinement. This study enhances the conventional electrical efficiency model by introducing the concept of electrical porosity. The improvement aims to mitigate the impact of isolated mold pores and sparse regions of current density distribution on electrical efficiency, focusing on the Mishrif Formation and quantitatively computing water saturation. Initially, the study area is categorized into three distinct rock-physics types of reservoirs using the Winland R35 method, with respective electrical porosities calculated. Subsequently, these results are integrated with the enhanced electrical efficiency model, and trial calculations are performed using geophysical well-logging data, followed by a comparison with core data. The findings reveal that the improved electrical efficiency model yields an average relative error of only 10.36 % compared to core data, whereas the respective errors for Archie's formula and traditional electrical efficiency models are 17.65 % and 20.92 %, indicating enhanced accuracy with the improved approach. Across different reservoir types, a decrease in electrical porosity proportion is observed with diminishing pore-throat radius. Additionally, the consistency of this trend is validated by nuclear magnetic resonance logging data. Lastly, the necessity of reservoir rock-physics type classification for electrical porosity computation is confirmed. For heterogeneous reservoirs, direct calculation of electrical porosity is infeasible, thus underscoring the essential groundwork of reservoir rock-physics type delineation. This study improves water saturation prediction accuracy and applicability by introducing electrical porosity to refine the conventional electrical efficiency model, holding significant implications for the exploration and development of complex reservoirs.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"236 ","pages":"Article 105656"},"PeriodicalIF":2.2,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143480348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-17DOI: 10.1016/j.jappgeo.2025.105658
Alejandro Vargas-Colorado , Mohsen Kazemnia Kakhki , José E. Barradas-Hernández , Sergio Márquez-Domínguez , Franco A. Carpio-Santamaría , José Piña-Flores
A representative velocity profile for Kumamoto city is presented in this study, derived from ambient seismic noise data collected by three sizes sensor arrays SM, M, and LL. Phase and group velocity dispersion curves for both Rayleigh and Love waves were estimated using techniques such as SPAC and cross-correlations. Additionally, Horizontal-to-Vertical Spectral Ratio (HVSR) analysis was performed individually for each array, and the resulting data were averaged to generate a single representative HVSR curve. By employing joint inversion under the diffuse field assumption, dispersion curves and HVSR data were concurrently fitted, allowing for the estimation of a 1D velocity profile. This approach effectively addresses the non-uniqueness inherent in inversion problems. Furthermore, upper modes were identified, and a comparative analysis of dispersion and HVSR curves was conducted against those of an established model, revealing notable discrepancies requiring thorough examination. Subsequently, seismic energy partitioning analysis was carried out, focusing on the vertical component. The findings were correlated with dispersion diagrams to confirm consistency in mode identification.
{"title":"Subsurface structure identification at the blind prediction site of ESG in Kumamoto under the diffuse field assumption","authors":"Alejandro Vargas-Colorado , Mohsen Kazemnia Kakhki , José E. Barradas-Hernández , Sergio Márquez-Domínguez , Franco A. Carpio-Santamaría , José Piña-Flores","doi":"10.1016/j.jappgeo.2025.105658","DOIUrl":"10.1016/j.jappgeo.2025.105658","url":null,"abstract":"<div><div>A representative velocity profile for Kumamoto city is presented in this study, derived from ambient seismic noise data collected by three sizes sensor arrays SM, M, and LL. Phase and group velocity dispersion curves for both Rayleigh and Love waves were estimated using techniques such as SPAC and cross-correlations. Additionally, Horizontal-to-Vertical Spectral Ratio (HVSR) analysis was performed individually for each array, and the resulting data were averaged to generate a single representative HVSR curve. By employing joint inversion under the diffuse field assumption, dispersion curves and HVSR data were concurrently fitted, allowing for the estimation of a 1D velocity profile. This approach effectively addresses the non-uniqueness inherent in inversion problems. Furthermore, upper modes were identified, and a comparative analysis of dispersion and HVSR curves was conducted against those of an established model, revealing notable discrepancies requiring thorough examination. Subsequently, seismic energy partitioning analysis was carried out, focusing on the vertical component. The findings were correlated with dispersion diagrams to confirm consistency in mode identification.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"235 ","pages":"Article 105658"},"PeriodicalIF":2.2,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-16DOI: 10.1016/j.jappgeo.2025.105654
Francisco Gamboa Ortega , Amin Bassrei , Francisco Cabrera Zambrano
Conventional velocity analysis estimates the normal moveout velocity which corresponds to a combination of the P-wave vertical velocity and the anisotropy parameter δ for a transversely isotropic medium with a vertical axis of symmetry. We propose in this study a joint estimation of (pseudo-acoustic) P-wave velocity and Thomsen parameters with new traveltime approximations and a deterministic inversion algorithm with regularization by derivative matrices. The new traveltime expressions are based on rational approximations, with analytical expressions that are simple to use. Therefore, the new approximations improved the joint inversion performance by reducing algebraic complexity. Computationally, the algorithm is efficient due to the use of small matrices; it simplifies calculations without losing precision. The experiments with synthetic models validated the approach and the numerical simulations indicated that the proposed approximations have in average an accuracy similar to the expressions available in the literature. The tested model considered lateral velocity variation, increasing the challenge in relation to a flat-layered model. In particular, the phase and group velocity approximations presented better accuracy between 40 and 60 degrees. For traveltime computation the proposed approach presented better accuracy for offsets greater than 4 km.
{"title":"New traveltime approximations for VTI media and estimation of the Thomsen parameters","authors":"Francisco Gamboa Ortega , Amin Bassrei , Francisco Cabrera Zambrano","doi":"10.1016/j.jappgeo.2025.105654","DOIUrl":"10.1016/j.jappgeo.2025.105654","url":null,"abstract":"<div><div>Conventional velocity analysis estimates the normal moveout velocity which corresponds to a combination of the P-wave vertical velocity and the anisotropy parameter δ for a transversely isotropic medium with a vertical axis of symmetry. We propose in this study a joint estimation of (pseudo-acoustic) P-wave velocity and Thomsen parameters with new traveltime approximations and a deterministic inversion algorithm with regularization by derivative matrices. The new traveltime expressions are based on rational approximations, with analytical expressions that are simple to use. Therefore, the new approximations improved the joint inversion performance by reducing algebraic complexity. Computationally, the algorithm is efficient due to the use of small matrices; it simplifies calculations without losing precision. The experiments with synthetic models validated the approach and the numerical simulations indicated that the proposed approximations have in average an accuracy similar to the expressions available in the literature. The tested model considered lateral velocity variation, increasing the challenge in relation to a flat-layered model. In particular, the phase and group velocity approximations presented better accuracy between 40 and 60 degrees. For traveltime computation the proposed approach presented better accuracy for offsets greater than 4 km.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"235 ","pages":"Article 105654"},"PeriodicalIF":2.2,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-16DOI: 10.1016/j.jappgeo.2025.105657
Aidin Kahbasi , Khiem T. Tran , Brady R. Cox , Aser Abbas
The ability to reliably image the subsurface is critical for designing and constructing infrastructure, especially in seismically active regions and areas with karstic geologies and underground anomalies. This study explores the application of 2D full-waveform inversion (FWI) of shear horizontal (SH) and Love waves to characterize shear wave velocity (Vs) and density down to a depth of 50 m. The FWI approach employs 2D elastic SH-wave equations for wave simulation and the adjoint-state gradient method with Tikhonov regularization for model updates. The applicability of this FWI approach was first verified using a synthetic four-layer subsurface model representing typical geology of north-central Florida, with soil overlying highly variable limestone. Following promising results from the synthetic study, the approach was applied to a dataset collected at a site near Newberry, Florida using a powerful mobile shaker source (T-Rex). The T-Rex vibroseis truck was instrumental in providing the low-frequency components (down to 5 Hz) essential for deep subsurface characterization. FWI successfully identified an underground anomaly and the depth to bedrock, which were verified through Standard Penetration Testing (SPT).
{"title":"Deep site characterization with full-waveform inversion of SH- and Love-waves induced by large mobile shaker","authors":"Aidin Kahbasi , Khiem T. Tran , Brady R. Cox , Aser Abbas","doi":"10.1016/j.jappgeo.2025.105657","DOIUrl":"10.1016/j.jappgeo.2025.105657","url":null,"abstract":"<div><div>The ability to reliably image the subsurface is critical for designing and constructing infrastructure, especially in seismically active regions and areas with karstic geologies and underground anomalies. This study explores the application of 2D full-waveform inversion (FWI) of shear horizontal (SH) and Love waves to characterize shear wave velocity (<em>Vs</em>) and density down to a depth of 50 m. The FWI approach employs 2D elastic SH-wave equations for wave simulation and the adjoint-state gradient method with Tikhonov regularization for model updates. The applicability of this FWI approach was first verified using a synthetic four-layer subsurface model representing typical geology of north-central Florida, with soil overlying highly variable limestone. Following promising results from the synthetic study, the approach was applied to a dataset collected at a site near Newberry, Florida using a powerful mobile shaker source (T-Rex). The T-Rex vibroseis truck was instrumental in providing the low-frequency components (down to 5 Hz) essential for deep subsurface characterization. FWI successfully identified an underground anomaly and the depth to bedrock, which were verified through Standard Penetration Testing (SPT).</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"235 ","pages":"Article 105657"},"PeriodicalIF":2.2,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.jappgeo.2025.105646
Hayder Abdulzahra Al-Dabbagh , Emad H. Al-Khersan , Eman Ali Al-Kanaan
The study area located between latitude (29o-31o) N and longitudes (42o-47o) E within the Mesopotamian zone inside Stable and Unstable Shelves. Airborne radioactivity survey of Iraq prepared by French Company (C.G.G.), (1974) was used to acquire the total count readings on a scale of 1:200.000 for Iraqi southern Desert. A regional radio-geological study was carried out to determine the relationship between various radioactive levels and the general structural and geological framework in the study area. The natural radiation background was calculated using trend surface analysis method, it ranged between (890) cps in Hour Al-Hammar region and (1160) cps in Iraqi-Saudi border of the area. The total radioactivity of the exposed geologic units and formations were ranged between (800_900) cps in Dibddiba Formation and (1100_1200) cps in Umm Er-Radhuma Formation, as well as that for Quaternary deposits it was found between (700_900) cps in slope deposits in Al-Salman region and (1100_1300) cps in valley fill deposits in Middle Member of Dammam Formation. Six sites of radiometric anomalies were noticed in the third order residual anomaly map. After the analysis of available geologic, structure and geophysical information of the study area, the nature and cause of these normally occurring anomalies and their relations with the mineral and lithological constituents of the rocks and their relation to the structural and geologic setting of the region was established and analyzed.
{"title":"Radioactivity of Outcropping Rock Formations / Iraqi Southern Desert","authors":"Hayder Abdulzahra Al-Dabbagh , Emad H. Al-Khersan , Eman Ali Al-Kanaan","doi":"10.1016/j.jappgeo.2025.105646","DOIUrl":"10.1016/j.jappgeo.2025.105646","url":null,"abstract":"<div><div>The study area located between latitude (29<sup>o</sup>-31<sup>o</sup>) N and longitudes (42<sup>o</sup>-47<sup>o</sup>) E within the Mesopotamian zone inside Stable and Unstable Shelves. Airborne radioactivity survey of Iraq prepared by French Company (C.G.G.), (1974) was used to acquire the total count readings on a scale of 1:200.000 for Iraqi southern Desert. A regional radio-geological study was carried out to determine the relationship between various radioactive levels and the general structural and geological framework in the study area. The natural radiation background was calculated using trend surface analysis method, it ranged between (890) cps in Hour Al-Hammar region and (1160) cps in Iraqi-Saudi border of the area. The total radioactivity of the exposed geologic units and formations were ranged between (800_900) cps in Dibddiba Formation and (1100_1200) cps in Umm Er-Radhuma Formation, as well as that for Quaternary deposits it was found between (700_900) cps in slope deposits in Al-Salman region and (1100_1300) cps in valley fill deposits in Middle Member of Dammam Formation. Six sites of radiometric anomalies were noticed in the third order residual anomaly map. After the analysis of available geologic, structure and geophysical information of the study area, the nature and cause of these normally occurring anomalies and their relations with the mineral and lithological constituents of the rocks and their relation to the structural and geologic setting of the region was established and analyzed.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"234 ","pages":"Article 105646"},"PeriodicalIF":2.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Meizhuang area, located in the South Poyang Depression, is characterized by the widespread occurrence of fold-fault systems and carbonate strata. With an average surface heat flow of 72 mW/m2, this region presents promising potential for developing geothermal energy. Our study aims to delineate the stratigraphic features and the components of the hydrothermal system through the interpretation of 117 broadband magnetotelluric (MT) soundings within this area. Prior dimensionality analysis using phase tensor revealed that the MT data reflects substantial lateral heterogeneities in the resistivity structure, necessitating a three-dimensional resistivity inversion. We employed the ModEM program to invert the off-diagonal components of MT impedance tensor data and comprehensively interpreted the electrical structure combined with geological information. The resistivity model major includes one low-resistivity anomaly and two high-resistivity anomalies. The conductive anomaly was attributed to the Cretaceous sandy mudstone overlaid on Permian limestone, suggesting a favorable reservoir-cap system in this location. The two high-resistivity bodies are distributed on either side of the conductive anomaly, corresponding to the Junshanhu uplift and the Meizhuang anticline respectively. These structures are mainly oriented in a northeast direction, forming a pattern of “two uplifts sandwiching one sag”. Results from this study indicate that the Permian carbonate rocks are regarded as the geothermal reservoir, while the overlying Quaternary and Cretaceous sediments serve as suitable caprocks. The presence of the Meizhuang anticline and the Junshanhu uplift facilitates deep hydrothermal circulation of groundwater along the faults.
{"title":"Electrical resistivity structure of the Meizhuang geothermal field in South Poyang Depression, China, revealed by 3-D magnetotelluric inversion","authors":"Chaofeng Wu , Dong Xu , Hailong Ye , Xiuquan Qiu , Hua Zhang","doi":"10.1016/j.jappgeo.2025.105653","DOIUrl":"10.1016/j.jappgeo.2025.105653","url":null,"abstract":"<div><div>The Meizhuang area, located in the South Poyang Depression, is characterized by the widespread occurrence of fold-fault systems and carbonate strata. With an average surface heat flow of 72 mW/m<sup>2</sup>, this region presents promising potential for developing geothermal energy. Our study aims to delineate the stratigraphic features and the components of the hydrothermal system through the interpretation of 117 broadband magnetotelluric (MT) soundings within this area. Prior dimensionality analysis using phase tensor revealed that the MT data reflects substantial lateral heterogeneities in the resistivity structure, necessitating a three-dimensional resistivity inversion. We employed the ModEM program to invert the off-diagonal components of MT impedance tensor data and comprehensively interpreted the electrical structure combined with geological information. The resistivity model major includes one low-resistivity anomaly and two high-resistivity anomalies. The conductive anomaly was attributed to the Cretaceous sandy mudstone overlaid on Permian limestone, suggesting a favorable reservoir-cap system in this location. The two high-resistivity bodies are distributed on either side of the conductive anomaly, corresponding to the Junshanhu uplift and the Meizhuang anticline respectively. These structures are mainly oriented in a northeast direction, forming a pattern of “two uplifts sandwiching one sag”. Results from this study indicate that the Permian carbonate rocks are regarded as the geothermal reservoir, while the overlying Quaternary and Cretaceous sediments serve as suitable caprocks. The presence of the Meizhuang anticline and the Junshanhu uplift facilitates deep hydrothermal circulation of groundwater along the faults.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"234 ","pages":"Article 105653"},"PeriodicalIF":2.2,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-04DOI: 10.1016/j.jappgeo.2025.105644
Viacheslav V. Spichak, Olga K. Zakharova
A feasibility study is carried out to assess the possibility of predicting the subsurface temperatures from seismic tomography data. To this end, we used seismic velocity data along the W-E profile in the Northern Tien Shan and geotherms from three boreholes located at different distances from the profile. To model the temperature prediction from seismic velocity data, we used a supervised artificial neural network (ANN) approach. Estimation of the temperature prediction accuracy was fulfilled in two modes: (1) extrapolation in depth, and (2) assessment in another geological environment. The accuracy estimates of the temperature predictions at depth have shown that the relative errors depend on the ratio between the depth for which the data are available and the target depth. In particular, temperature prediction from seismic S-wave velocity data is markedly more accurate than the prediction from P-wave velocity if the target depth exceeds the source depth 5–10 times. On the other hand, in extrapolation to a depth less than twice the initial depth the average relative errors are 1 % and 2 %, accordingly. The accuracy analysis of temperature predictions in different geological environments showed that the accuracy of temperature prediction practically does not depend on the spacing between the locations of the “source” and “target” boreholes. On average, the accuracy of the prediction from P- and S-waves is approximately similar, with average relative errors of 4.8 and 4.7 %, respectively. It can be concluded that neural network prediction of the subsurface temperature from seismic velocity data can be performed with acceptable accuracy (at least, at borehole depth scale) and can be used as a seismological geothermometer.
{"title":"Seismological geothermometer. Part I: Neural network modeling of the temperature prediction from seismic velocity data at borehole depth scale","authors":"Viacheslav V. Spichak, Olga K. Zakharova","doi":"10.1016/j.jappgeo.2025.105644","DOIUrl":"10.1016/j.jappgeo.2025.105644","url":null,"abstract":"<div><div>A feasibility study is carried out to assess the possibility of predicting the subsurface temperatures from seismic tomography data. To this end, we used seismic velocity data along the W-E profile in the Northern Tien Shan and geotherms from three boreholes located at different distances from the profile. To model the temperature prediction from seismic velocity data, we used a supervised artificial neural network (ANN) approach. Estimation of the temperature prediction accuracy was fulfilled in two modes: (1) extrapolation in depth, and (2) assessment in another geological environment. The accuracy estimates of the temperature predictions at depth have shown that the relative errors depend on the ratio between the depth for which the data are available and the target depth. In particular, temperature prediction from seismic <em>S</em>-wave velocity data is markedly more accurate than the prediction from <em>P</em>-wave velocity if the target depth exceeds the source depth 5–10 times. On the other hand, in extrapolation to a depth less than twice the initial depth the average relative errors are 1 % and 2 %, accordingly. The accuracy analysis of temperature predictions in different geological environments showed that the accuracy of temperature prediction practically does not depend on the spacing between the locations of the “source” and “target” boreholes. On average, the accuracy of the prediction from <em>P</em>- and <em>S</em>-waves is approximately similar, with average relative errors of 4.8 and 4.7 %, respectively. It can be concluded that neural network prediction of the subsurface temperature from seismic velocity data can be performed with acceptable accuracy (at least, at borehole depth scale) and can be used as a seismological geothermometer.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"234 ","pages":"Article 105644"},"PeriodicalIF":2.2,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-04DOI: 10.1016/j.jappgeo.2025.105645
Erkan Ateş , Osman Uyanık
Installing strong ground motion measuring devices in existing structures is significant for earthquake engineering and building safety to monitor whether the structures can be damaged or not. This study determined with different spectral ratio methods the dominant vibration period and amplification characteristics of both the structure and the ground from earthquake and noise records and compared the results. For this purpose, online-monitored accelerometer devices were placed on the top floor of a 5-story public building that was improved in 2008, on the ground where it was built, and on the rock approximately 1 km away from this building. MASW measurement was taken to determine the ground class of the area where the accelerometer device was installed on the ground right next to the building. Many earthquake records of different distances and magnitudes were obtained by the fixed devices located in the building, on the ground, and the rock. Spectral ratio methods were applied to the recorded earthquakes according to the reference station method and horizontal/vertical ratio methods according to the single station method. In addition to the analyses applied to the earthquake records, noise measurements were taken at night on the building floors and ground, and these measurements were evaluated according to the horizontal/vertical spectral ratio method and floor spectral ratio methods. As a result of all the analyses, the amplifications, dominant frequencies, and damping ratio of the building and the ground were determined, and the interference status of the building and the ground was examined. As a result, it was observed that the dominant frequency of the building, the spectral ratio amplification, and the damping ratio values of the building were approximately the same by using different spectral ratio methods for earthquake and noise data. In addition, there was a slight increase in the building's dominant period as a result of earthquakes that occurred at different times.
{"title":"Comparison of soil-structure interaction obtained from spectral ratio methods applied to earthquake and microtremor records","authors":"Erkan Ateş , Osman Uyanık","doi":"10.1016/j.jappgeo.2025.105645","DOIUrl":"10.1016/j.jappgeo.2025.105645","url":null,"abstract":"<div><div>Installing strong ground motion measuring devices in existing structures is significant for earthquake engineering and building safety to monitor whether the structures can be damaged or not. This study determined with different spectral ratio methods the dominant vibration period and amplification characteristics of both the structure and the ground from earthquake and noise records and compared the results. For this purpose, online-monitored accelerometer devices were placed on the top floor of a 5-story public building that was improved in 2008, on the ground where it was built, and on the rock approximately 1 km away from this building. MASW measurement was taken to determine the ground class of the area where the accelerometer device was installed on the ground right next to the building. Many earthquake records of different distances and magnitudes were obtained by the fixed devices located in the building, on the ground, and the rock. Spectral ratio methods were applied to the recorded earthquakes according to the reference station method and horizontal/vertical ratio methods according to the single station method. In addition to the analyses applied to the earthquake records, noise measurements were taken at night on the building floors and ground, and these measurements were evaluated according to the horizontal/vertical spectral ratio method and floor spectral ratio methods. As a result of all the analyses, the amplifications, dominant frequencies, and damping ratio of the building and the ground were determined, and the interference status of the building and the ground was examined. As a result, it was observed that the dominant frequency of the building, the spectral ratio amplification, and the damping ratio values of the building were approximately the same by using different spectral ratio methods for earthquake and noise data. In addition, there was a slight increase in the building's dominant period as a result of earthquakes that occurred at different times.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"234 ","pages":"Article 105645"},"PeriodicalIF":2.2,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143372063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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