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Radioactivity of Outcropping Rock Formations / Iraqi Southern Desert
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-13 DOI: 10.1016/j.jappgeo.2025.105646
Hayder Abdulzahra Al-Dabbagh , Emad H. Al-Khersan , Eman Ali Al-Kanaan
{"title":"Radioactivity of Outcropping Rock Formations / Iraqi Southern Desert","authors":"Hayder Abdulzahra Al-Dabbagh ,&nbsp;Emad H. Al-Khersan ,&nbsp;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}
引用次数: 0
Electrical resistivity structure of the Meizhuang geothermal field in South Poyang Depression, China, revealed by 3-D magnetotelluric inversion
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-11 DOI: 10.1016/j.jappgeo.2025.105653
Chaofeng Wu , Dong Xu , Hailong Ye , Xiuquan Qiu , Hua Zhang
{"title":"Electrical resistivity structure of the Meizhuang geothermal field in South Poyang Depression, China, revealed by 3-D magnetotelluric inversion","authors":"Chaofeng Wu ,&nbsp;Dong Xu ,&nbsp;Hailong Ye ,&nbsp;Xiuquan Qiu ,&nbsp;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}
引用次数: 0
Seismological geothermometer. Part I: Neural network modeling of the temperature prediction from seismic velocity data at borehole depth scale
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-04 DOI: 10.1016/j.jappgeo.2025.105644
Viacheslav V. Spichak, Olga K. Zakharova
{"title":"Seismological geothermometer. Part I: Neural network modeling of the temperature prediction from seismic velocity data at borehole depth scale","authors":"Viacheslav V. Spichak,&nbsp;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}
引用次数: 0
Comparison of soil-structure interaction obtained from spectral ratio methods applied to earthquake and microtremor records
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-04 DOI: 10.1016/j.jappgeo.2025.105645
Erkan Ateş , Osman Uyanık
{"title":"Comparison of soil-structure interaction obtained from spectral ratio methods applied to earthquake and microtremor records","authors":"Erkan Ateş ,&nbsp;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}
引用次数: 0
Gravity gradient signal extraction based on time-frequency feature threshold method
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-03 DOI: 10.1016/j.jappgeo.2025.105643
Tao Jiang , Bohai Ke , Xiaobing Yu , Li Yu , Meng Yang , Ji Fan , Chenyuan Hu , Wei Feng , Huafeng Liu , Min Zhong , Liangcheng Tu , Zebing Zhou
{"title":"Gravity gradient signal extraction based on time-frequency feature threshold method","authors":"Tao Jiang ,&nbsp;Bohai Ke ,&nbsp;Xiaobing Yu ,&nbsp;Li Yu ,&nbsp;Meng Yang ,&nbsp;Ji Fan ,&nbsp;Chenyuan Hu ,&nbsp;Wei Feng ,&nbsp;Huafeng Liu ,&nbsp;Min Zhong ,&nbsp;Liangcheng Tu ,&nbsp;Zebing Zhou","doi":"10.1016/j.jappgeo.2025.105643","DOIUrl":"10.1016/j.jappgeo.2025.105643","url":null,"abstract":"<div><div>Gravity gradient, defined as the spatial derivative of gravitational acceleration, represents the detailed variation of the gravity field and plays a significant role in resource exploration and auxiliary navigation. Airborne gravity gradient measurement is an important method for obtaining high-precision gravity gradient data. Compared to traditional gravity measurement techniques, it offers superior measurement efficiency and provides high-frequency information of gravity field which reveals small-scale terrain features. However, it also introduces more high-frequency measurement noise. Due to the randomness of Earth's topography and resource distribution, the high-frequency characteristics of gravity gradient signals are mainly concentrated in specific time and frequency ranges, exhibiting distinct time-frequency features. This paper employs the VMD and Hilbert transform to obtains the time-frequency features of gravity gradient signal, and proposes a time-frequency feature threshold method to extract gravity gradient signal. This method can accurately analyze and extract the gravity gradient signals components without being affected by the same frequency noise, suppressing 78 % of the noise in simulation data. Additionally, the proposed method is validated in the gravity gradient data of actual terrain, demonstrating over 19 % improvement compared to traditional smooth filter and wavelet threshold methods. Furthermore, it effectively retains the high-frequency characteristics of gravity gradient signal, enhancing the advantages of airborne gravity gradient signals</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"234 ","pages":"Article 105643"},"PeriodicalIF":2.2,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349184","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}
引用次数: 0
Application of 3-D inversion of AMT data in exploration of concealed nonmetallic deposits: A Case Study on the Huashitou Mountain fluorite deposit in Beishan metallogenic belt, China
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-01 DOI: 10.1016/j.jappgeo.2025.105632
Jianhui Hu , Liuyang Xu , Yaotian Yin , Xu Jia , Ping Qi , Zhan Liang , Peng Su , Cheng Liu , Weidong Tang , Long Chen , Yanzhou Wang , Lin Liu
{"title":"Application of 3-D inversion of AMT data in exploration of concealed nonmetallic deposits: A Case Study on the Huashitou Mountain fluorite deposit in Beishan metallogenic belt, China","authors":"Jianhui Hu ,&nbsp;Liuyang Xu ,&nbsp;Yaotian Yin ,&nbsp;Xu Jia ,&nbsp;Ping Qi ,&nbsp;Zhan Liang ,&nbsp;Peng Su ,&nbsp;Cheng Liu ,&nbsp;Weidong Tang ,&nbsp;Long Chen ,&nbsp;Yanzhou Wang ,&nbsp;Lin Liu","doi":"10.1016/j.jappgeo.2025.105632","DOIUrl":"10.1016/j.jappgeo.2025.105632","url":null,"abstract":"<div><div>This study utilized audio-frequency magnetotelluric (AMT) data collected from a concealed fluorite deposit on Huashitou Mountain in the Beishan metallogenic belt to obtain a 3-D resistivity model beneath the deposit. The fluorite ore-forming mechanism was determined and is discussed in combination with previous high-resolution magnetic and induced-polarization imaging results. Our study revealed a large high-resistivity body, R2 (&gt; 1000 Ω·m), corresponding to the low induced-polarization and low-magnetic region that extends from 40 to &gt; 80 m in depth. We suggest that this corresponds to the Indosinian intrusive granite, and potentially serves as a fluorite mineralization rock mass. A highly conductive zone, C3 (&lt; 3 Ω·m), extending from approximately 20 to 300 m, or even deeper, was interpreted as a deep fault/fracture zone functioning as a fluid pathway for fluorite mineralization. Two smaller conductive zones, C1 and C2 (&lt; 20 Ω·m), appear above the high-resistivity granite intrusion. These zones correspond well with high induced-polarization anomalies (&gt; 2.5 % threshold), relatively high-△T anomalies (−50 nT), and hematite alteration areas shown on the geological cross-sections. These zones were interpreted as two near-surface secondary fault structures. The aforementioned fault structures are believed to have formed before the main mineralization period of the fluorite deposit and were subsequently reactivated during intense tectonic-magmatic activity in the Late Hercynian. Hot fluids enriched with volatile components (e.g., F and CO<sub>2</sub>) were transported along the deep fault, represented by C3, from the lower crust to the near-surface secondary fault zones (represented by C1 and C2). These fluids interacted with the calcic plagioclase in alkaline granite magma to form fluorite (mainly composing CaF<sub>2</sub>) through calcium extraction. Further, the process led to hydrothermal alteration, resulting in associated iron-oxide mineralization or silicification alteration zones, as well as alterations related to a sedimentary layer such as kaolinization and chloritization. These zones exhibit high conductivity because of their significant porosity and the presence of fluids or metal sulfides.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"233 ","pages":"Article 105632"},"PeriodicalIF":2.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097096","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}
引用次数: 0
A nonnegative constrained method for high-precision downward continuation of gravity field data
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-01 DOI: 10.1016/j.jappgeo.2025.105625
Tianyou Liu , Xiaoniu Zeng , Xihai Li , Longwei Chen , Jihao Liu , Xiaofeng Tan , Hongru Li
{"title":"A nonnegative constrained method for high-precision downward continuation of gravity field data","authors":"Tianyou Liu ,&nbsp;Xiaoniu Zeng ,&nbsp;Xihai Li ,&nbsp;Longwei Chen ,&nbsp;Jihao Liu ,&nbsp;Xiaofeng Tan ,&nbsp;Hongru Li","doi":"10.1016/j.jappgeo.2025.105625","DOIUrl":"10.1016/j.jappgeo.2025.105625","url":null,"abstract":"<div><div>Gravity downward continuation is an effective method for processing and interpreting gravity data. Finding a gravity downward continuation method with high accuracy and stability is a persistent and popular research topic. At present, there are two common strategies for reducing the ill-posedness inherent in the downward continuation of potential fields, namely, regularization, and the design of wavenumber domain filtering operators. However, these downward continuation strategies often result in unsatisfactory continuation accuracy due to excessive smoothing of the downward continued field. To improve the stability and accuracy of the gravity downward continuation calculation, we construct an equivalent mathematical model of gravity downward continuation. This model is not only equivalent to the traditional gravity downward continuation model but also introduces nonnegative constraints into gravity downward continuation. This approach effectively reduces the ill-posedness of gravity downward continuation. Based on the newly proposed gravity downward continuation model, we propose a constrained gravity downward continuation method. Comparison experiments based on a synthetic gravity model and real gravity anomaly data show that, compared with the other four high performance unconstrained potential field downward continuation methods, the constrained downward continuation method proposed in this paper produces a more stable and accurate downward continued gravity field when the observed data are corrupted by noise.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"233 ","pages":"Article 105625"},"PeriodicalIF":2.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097099","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}
引用次数: 0
Joint Lamé constants and P-wave anisotropic parameter estimation of vertical transverse isotropy coal-measure gas reservoir
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-01 DOI: 10.1016/j.jappgeo.2025.105638
Haibo Wu , Yaping Huang , Yanhui Huang , Ze Bai , Jian Lei
{"title":"Joint Lamé constants and P-wave anisotropic parameter estimation of vertical transverse isotropy coal-measure gas reservoir","authors":"Haibo Wu ,&nbsp;Yaping Huang ,&nbsp;Yanhui Huang ,&nbsp;Ze Bai ,&nbsp;Jian Lei","doi":"10.1016/j.jappgeo.2025.105638","DOIUrl":"10.1016/j.jappgeo.2025.105638","url":null,"abstract":"<div><div>The Lamé constants (<em>λ</em> and <em>μ</em>) and anisotropic parameters (<em>ε</em>, <em>γ</em>, and <em>δ</em>) are the key quantities to calculate the brittleness indices and fluid factors in unconventional reservoirs, supporting high-precision seismic data processing as well as anisotropy characterization. However, accurately estimating these quantities using the traditional amplitude variation with offset (AVO) inversion based on the assumption of isotropic media is difficult. Therefore, we conducted a three-parameter AVO inversion and estimated the Lamé constants and P-wave anisotropic parameter (<em>ε</em>) for media with vertically transverse isotropy (VTI), using a coal-measure gas reservoir as an example. A new PP-wave reflection coefficient approximation equation for VTI media was derived based on Rüger's approximation. Subsequently, we analyzed the accuracy of the new equation and designed a strategy for estimating the Lamé constants and P-wave anisotropic parameter. The method was tested and applied using a synthetic seismic record and a cross-well seismic profile. The results demonstrate that the Lamé constants and P-wave anisotropic parameter estimated by both the synthetic seismic record (with or without noise) and cross-well seismic profile (at the well location), agree closely with the well-logging calculated curves. Therefore, the method can reasonably be extended to other similar unconventional reservoirs with certain constraints.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"233 ","pages":"Article 105638"},"PeriodicalIF":2.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097102","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}
引用次数: 0
Source influences of grounded-wire transient electromagnetic soundings: A systematic review and investigation
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-01 DOI: 10.1016/j.jappgeo.2025.105633
Weiying Chen , Wanting Song , Sixu Han , Kangxin Lei , Yulian Zhu
{"title":"Source influences of grounded-wire transient electromagnetic soundings: A systematic review and investigation","authors":"Weiying Chen ,&nbsp;Wanting Song ,&nbsp;Sixu Han ,&nbsp;Kangxin Lei ,&nbsp;Yulian Zhu","doi":"10.1016/j.jappgeo.2025.105633","DOIUrl":"10.1016/j.jappgeo.2025.105633","url":null,"abstract":"<div><div>Grounded-wire sources serve as critical transmitting elements in the transient electromagnetic method (TEM). Despite the sustained interest in understanding the impact of grounded-wire sources on the data collected, there remains a notable deficiency in thorough research and discourse on this topic. This study employs numerical simulations and field measurements to investigate the various factors that influence the effects of grounded-wire sources on TEM soundings, particularly focusing on aspects such as size, shape, shallow local anomalies, and the turn-off effect. The findings indicate that the dimensions of the source can significantly affect the early signals observed. Neglecting the actual shape of the source may lead to considerable deviations in the inversion results. Furthermore, local electrical heterogeneities beneath the source can produce overprint effects, resulting in substantial distortions of the observed signals. The turn-off time of the grounded-wire source exhibits a positive correlation with both the source length and the transmitting current, while it shows a negative correlation with grounding resistance. It is recommended that practitioners meticulously document the shape and position of the source. Additionally, it is advisable to position the source in regions characterized by simple and flat geological formations whenever feasible. The design of the source length and the intensity of the transmitting current should be carefully calibrated to accommodate the varying detection requirements for both shallow and deep targets. The implications of this research are significant for the construction, data processing, and interpretation of TEM soundings that utilize grounded-wire sources.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"233 ","pages":"Article 105633"},"PeriodicalIF":2.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143096571","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}
引用次数: 0
An improved stochastic inversion of P- to S-wave velocity ratio and compressional modulus based on fast Fourier transform moving average co-simulation
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-01 DOI: 10.1016/j.jappgeo.2025.105642
Chen Zhao , Jie Liang , Jiajia Zhang , Yinguo Zhang , Jing Sun , Jing Liao
{"title":"An improved stochastic inversion of P- to S-wave velocity ratio and compressional modulus based on fast Fourier transform moving average co-simulation","authors":"Chen Zhao ,&nbsp;Jie Liang ,&nbsp;Jiajia Zhang ,&nbsp;Yinguo Zhang ,&nbsp;Jing Sun ,&nbsp;Jing Liao","doi":"10.1016/j.jappgeo.2025.105642","DOIUrl":"10.1016/j.jappgeo.2025.105642","url":null,"abstract":"<div><div>The stochastic seismic amplitude-versus-angle (AVA) inversion is extensively utilized in the estimation of elastic properties and rock physics parameters from seismic data. This method can substantially improve the resolution of reservoir identification in areas where well data are available. Compared with conventional sequential simulation methods, the fast Fourier transform moving average (FFT-MA) simulation exhibits a superior computational efficiency. However, given the limitations of FFT-MA simulation in the simultaneous simulation of multiple elastic properties (such as compressional modulus, VP/VS, and density), the effective application of this method in seismic AVA inversion is challenging. In this study, we propose an FFT-MA co-simulation method for the simultaneous simulation of multiple elastic parameters. This approach establishes possible models constrained by the joint probability distributions of inverted properties, which enhances the accuracy of co-simulated results. Furthermore, we introduce an iterative update method designed to enhance convergence during inversion processes and increase the inversion accuracy. Consequently, an efficient stochastic inversion method is developed through the combination of the FFT-MA Co-simulation method with the iterative update method. The effectiveness of the proposed inversion method is validated through numerical examples and field data application.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"233 ","pages":"Article 105642"},"PeriodicalIF":2.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143096573","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}
引用次数: 0
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