Geophysical Prospecting最新文献

{"title":"Discretization of small-scale, stratigraphic heterogeneities and its impact on the seismic response: Lessons from the application of process-based modelling","authors":"Andrea Cuesta Cano, Azin Karimzadanzabi, Joep Elisabeth Anton Storms, Guillaume Rongier, Dirk Jacob Verschuur, Allard Willem Martinius","doi":"10.1111/1365-2478.70015","DOIUrl":"https://doi.org/10.1111/1365-2478.70015","url":null,"abstract":"<p>Reducing the uncertainty of reservoir characterization requires to better identify the small-scale structures of the subsurface from the available data. Studying the seismic response of meter-scale, stratigraphic heterogeneities typically relies on the generation of reservoir models based on outcrop examples and their forward seismic modelling. To bridge geological information and seismic modelling, these methods allocate values of acoustic properties, such as mass-density and P-wave velocity, according to discretized properties like layer-type lithology or facies units. This strategy matches the current workflow in seismic data inversion in industry, where modelling workflows are based on lithofacies distributions. However, from stratigraphic modelling, we know that meter-scale heterogeneities occur within certain facies and lithologies. Here, we evaluate the difference on the seismic response between allocating acoustic properties in a grain size–based, semi-continuous manner versus discretized manners based on lithology and facies classifications. To do so, we generate a reference geological simulation that we populate with acoustic properties, mass-density and P-wave velocity, using three different strategies: (1) based on grain size distribution; (2) based on facies distribution; and (3) based on lithology. The method we propose includes the generation of realistic geological simulations based on stratigraphic modelling and the transformation of its output into acoustic properties, honouring the intra-lithology and intra-facies, small-scale structures. We, then, generate seismic data by applying a forward seismic modelling workflow. The synthetic data show that the grain size–based simulation allows the identification of small-scale, stratigraphic heterogeneities, such as beds with strong density and velocity contrasts. These stratigraphic structures are smoothened or may completely disappear in the facies and lithology discretized simulations and, therefore, are not (well) represented in the synthetic seismic data. Recognizing meter-scale, stratigraphic heterogeneities is relevant for the characterization of the fluid flow in the reservoir. However, current discrete and lithology-based strategies in seismic inversion are not able to resolve such heterogeneities because real subsurface properties are not discrete properties but continuous, unless there are stratigraphic discontinuities such as erosional surfaces or faults. This research works towards a better understanding of the relationship between changes in these continuous properties and the observed seismic data by introducing greater complexity into the discretized geological simulations. Here, we use synthetic seismic images with the goal of eventually aiding in fine-tuning seismic inversion methodologies applied to real seismic data. One pathway is to foster the development of inversion approaches that can leverage stratigraphic modelling to get stronger geological priors and rep","PeriodicalId":12793,"journal":{"name":"Geophysical Prospecting","volume":"73 4","pages":"1280-1300"},"PeriodicalIF":1.8,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/1365-2478.70015","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143845835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-dimensional gravity inversion based on the Hamiltonian Monte Carlo method","authors":"Ya Xu,&nbsp;Wei Chu,&nbsp;Song Huang,&nbsp;Rui Guo,&nbsp;Shupeng Lu,&nbsp;Fangzhou Nan","doi":"10.1111/1365-2478.70016","DOIUrl":"https://doi.org/10.1111/1365-2478.70016","url":null,"abstract":"<p>In geophysics, Bayesian inversion methods are of significant prominence. Here, we present a novel approach utilizing the Hamiltonian Monte Carlo (HMC) method in gravity inversion for elucidating three-dimensional (3D) density structures. HMC provides a multi-dimensional sampling method that demonstrates enhanced optimization efficiency, facilitating the attainment of distant proposals with elevated acceptance probabilities. Its applicability also extends to resolving linear inverse problems. Three synthetic models of cubic bodies, dipping dykes and a combined model were designed for tests. The testes underscore the promising potential of HMC in recovering subsurface density source bodies and giving the uncertainty of the inversion model. Furthermore, an inversion test conducted on the Vinton salt dome yields a reasonable 3D distribution of cap rock, consistent with prior studies in this area. The modelling and field experiments showed that the proposed HMC gravity inversion method had higher accuracy and application potential.</p>","PeriodicalId":12793,"journal":{"name":"Geophysical Prospecting","volume":"73 4","pages":"1301-1314"},"PeriodicalIF":1.8,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143845836","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}

{"title":"Sequential multi-dimensional parameter inversion of induction logging data","authors":"Durra H. Saputera,&nbsp;Morten Jakobsen,&nbsp;K. W. A. van Dongen,&nbsp;Nazanin Jahani","doi":"10.1111/1365-2478.70017","DOIUrl":"https://doi.org/10.1111/1365-2478.70017","url":null,"abstract":"<p>Structural information about the subsurface near the borehole can be obtained from reconstructed conductivity distributions. These distributions may be reconstructed via the inversion of deep-sensing electromagnetic induction log data. Unfortunately, these complex media often display anisotropy and structural variations in both horizontal and vertical directions, making the three-dimensional inversion computationally demanding and ill-posed. To address these challenges, we introduce a sequential inversion strategy of deep-sensing electromagnetic induction logging data that is measured while drilling. For the inversion at each logging position, we employ a matrix-free implementation of the adjoint integral equation method and a quasi-Newton algorithm. To tackle the ill-posed nature of the problem, we regularize the inverse problem by employing a multi-dimensional inversion parameter technique that shifts from zero- to three-dimensional parameterization. The model derived from the inversion of the data at multiple positions is incrementally integrated by utilizing the sensitivity data at each logging position. To validate our approach, we tested our method on simulated data using an anisotropic model. These experiments show that this approach produces a good reconstruction of the true conductivity for the whole track while only doing the inversion at a single position at a time.</p>","PeriodicalId":12793,"journal":{"name":"Geophysical Prospecting","volume":"73 4","pages":"1315-1332"},"PeriodicalIF":1.8,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143845834","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}

{"title":"Multi-synchrosqueezing polynomial chirplet transform and its application to seismic thin interbeds analysis","authors":"Fang Li,&nbsp;Hui Chen,&nbsp;Yuanwei Song,&nbsp;Rui Wang,&nbsp;Bairong Ding","doi":"10.1111/1365-2478.70014","DOIUrl":"https://doi.org/10.1111/1365-2478.70014","url":null,"abstract":"<p>Thin interbeds are important geological structures in seismic exploration, and the analysis of their thickness variations is a key step in seismic interpretation. As a typical signal-processing technology, the time–frequency analysis method maps one-dimensional signals to the two-dimensional time–frequency domain, which can capture the changes of the instantaneous frequency. On this basis, the time–frequency analysis method can be used to analyse the thickness changes of thin interbeds. To analyse the thickness changes more accurately, the adopted time–frequency analysis method needs to have high time–frequency resolution and robustness. This paper proposes a novel method named the multi-synchrosqueezing polynomial chirplet transform. First, the second-order instantaneous frequency estimation operator is obtained through the corrected polynomial chirplet transform. Then, through squeezing and rearranging, the fuzzy time–frequency energy is gradually concentrated on the corresponding second-order multiple instantaneous frequency estimation operator to obtain the multi-synchrosqueezing polynomial chirplet transform. Simulated signals are used to demonstrate that multi-synchrosqueezing polynomial chirplet transform has robustness while improving time–frequency resolution. Simultaneously, simulated and real seismic signals are used to verify that the proposed method can analyse the thickness variation of thin interbeds.</p>","PeriodicalId":12793,"journal":{"name":"Geophysical Prospecting","volume":"73 4","pages":"1268-1279"},"PeriodicalIF":1.8,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143845986","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}

{"title":"Evaluating the applicability of a 2D weighted compact gravity inversion method for determining crustal undulations and thicknesses in the Aegean region","authors":"M. B. Doğan","doi":"10.1111/1365-2478.70001","DOIUrl":"https://doi.org/10.1111/1365-2478.70001","url":null,"abstract":"<p>This study introduces the application of the 2D weighted compact gravity inversion technique to model crustal thickness and intracrustal discontinuities in the Aegean region, encompassing both marine and terrestrial areas over a significant area of 430 km × 333 km. The method utilized advanced spectral analysis and upward continuation techniques to enhance the quality of Bouguer data, effectively mitigating surface noise. The findings reveal a remarkable correlation (over 99.9%) between observed and theoretical data, demonstrating the algorithm's robustness in accurately delineating crustal features. Depth estimates for the Conrad (2.7 g/cm³) and Moho (3.3 g/cm³) discontinuities were obtained, highlighting distinct density variations across discontinuity zones. Furthermore, the relationship between intracrustal discontinuities and seismicity was examined, revealing that earthquakes predominantly follow the Conrad boundary. Notably, this study uniquely produces 2D depth contour maps of Conrad and Moho discontinuities from specific density derived from gravity inversion sections. The results indicate that this method is a valuable tool for understanding crustal dynamics, suggesting potential applications for future tectonic assessments, especially in regional studies. The successful application of this novel technique emphasizes its significance in advancing geophysical modelling and enhances our understanding of isostatic evaluation in the Aegean region for further studies.</p>","PeriodicalId":12793,"journal":{"name":"Geophysical Prospecting","volume":"73 4","pages":"1243-1254"},"PeriodicalIF":1.8,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/1365-2478.70001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The potential of a novel gravity research method in geophysics","authors":"Lajos Völgyesi,&nbsp;Gyula Tóth","doi":"10.1111/1365-2478.70008","DOIUrl":"https://doi.org/10.1111/1365-2478.70008","url":null,"abstract":"<p>The gravity force, as a vector, has both magnitude (length) and direction. Previously, with the measurement methods employed, only the magnitude (length) of the vector was measured; there was no possibility in geophysical practice to measure the direction of the vector. Previously, the method of astronomic positioning was used to determine the vertical direction. This was extremely time-consuming, taking several months, complex and expensive procedure, used in geodesy at some points to determine the values of vertical deflection. Recently, revolutionary changes have been made in this area, with the development of a new, quick and simple method for determining the local vertical direction, which is more accurate than ever before. In contrast to the previous extremely slow process, with the computer-controlled, fully automated QDaedalus measurement system, a single person can perform multiple high-precision measurements at various locations overnight, making the appropriate quantity and quality of measurement results suitable for geophysical structural research purposes. In this article, we briefly describe the operation of the QDaedalus system and draw attention to the geophysical applicability of the method in terms of detectable mass anomalies and useful station spacing using astrogeodetic field measurements. To demonstrate this, astrogeodetic measurements were also carried out along a 4 km long section, from which the deflection of the vertical values and geoid heights were determined. Our measurements were compared with the normal values calculated with the global gravity model of high resolution (Global Gravity Model plus). As the deflection of the vertical values calculated with this model includes the effect of the surface topographic masses at the resolution of the model, the difference between the measured and the modelled values is practically a function of subsurface density anomalies. At the same time, we performed model calculations showing how density anomalies of different extents assumed at different depths affect the value of the vertical deflections and the geoid anomalies.</p>","PeriodicalId":12793,"journal":{"name":"Geophysical Prospecting","volume":"73 4","pages":"1255-1267"},"PeriodicalIF":1.8,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846039","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}

{"title":"Resolving key issues of mature Mumbai offshore fields using ocean bottom node seismic interpretation","authors":"Uday Shanker Mishra,&nbsp;Saumya Kanti Goswami,&nbsp;Souvik Sengupta,&nbsp;Subhankar Basu,&nbsp;Srilata Mohapatra,&nbsp;Anand Prakash","doi":"10.1111/1365-2478.70003","DOIUrl":"https://doi.org/10.1111/1365-2478.70003","url":null,"abstract":"<p>Neelam–Heera fields are located in Mumbai offshore basin and are significant contributors to India's oil and gas production. These mature oil and gas fields are producing mainly from Eocene–Oligocene carbonate reservoirs. Key challenges of Neelam–Heera fields include seismic imaging issues in areas perturbed by shallow gas, discrepancy in time and depth structures caused by lateral and vertical velocity variations and delineation of karst/discontinuities in the Neelam–Bassein formation to improve well planning and avoid mud loss. The seismic interpretation study we conducted used recent ocean bottom node seismic data to provide new insights into these challenges and are discussed in this paper. An integrated study scaling from interpretive processing to high-resolution mapping/attribute analysis was conducted to solve the key challenges of the Neelam–Heera fields. A significant improvement is seen in the imaging of the Neelam–Heera area because of prestack depth migration processing of ocean bottom node data, which led to detailed mapping and better understanding of various formations. One of the key challenges was to understand the structural changes in areas masked by shallow gas clouds in the Heera high area. The PP data could not provide clear imaging of areas masked by shallow gas; however, the PS data is not affected by fluid presence and provided imaging below the gas cloud. The gas-bearing Bandra formation in the crestal part of the Heera field is mapped with the help of PS data. The Neelam–Heera area shows prominent trends related to a velocity anomaly at a shallow level (dissolution features), forming the valleys in the time cube that are not seen in the depth cube. The key formations are mapped carefully with the integration of a depth cube. The new depth maps provided insights in areas hindered by previous false structures and are key to future development planning. To gain insights on karstification and mud-loss issues in Neelam field (Bassein formation), various structural attributes were derived and correlated with well data. Most positive/negative curvature attributes at different azimuthal stacks alongside variance maps provided detailed high-resolution insights on faults/lineaments/fractures, and posting of well mud-loss information validated the disturbed-zone-related mud-loss areas. The availability of ocean bottom node data with high-quality processing and imaging and subsequent detailed seismic interpretation using PP and PS data provided new insights to solve the key challenges of Neelam–Heera fields. The key outcome of this study includes an improved understanding of areas perturbed by shallow gas and better depth maps for integration into the future development model in areas with discrepancies caused by significant lateral and vertical velocity variations. In addition, we were better able to delineate karst/discontinuities in the Neelam–Bassein formation, which improved well planning and helped avoid mud loss.</p>","PeriodicalId":12793,"journal":{"name":"Geophysical Prospecting","volume":"73 4","pages":"1204-1211"},"PeriodicalIF":1.8,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143845792","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}

{"title":"Sensitivity analysis with a 3D mixed-dimensional code for direct current geoelectrical investigations of landfills: synthetic tests","authors":"Lorenzo Panzeri,&nbsp;Alessio Fumagalli,&nbsp;Laura Longoni,&nbsp;Monica Papini,&nbsp;Diego Arosio","doi":"10.1111/1365-2478.70006","DOIUrl":"https://doi.org/10.1111/1365-2478.70006","url":null,"abstract":"<p>Electrical resistivity tomography is a suitable technique for non-invasive monitoring of municipal solid waste landfills, but accurate sensitivity analysis is necessary to evaluate the effectiveness and reliability of geoelectrical investigations and to properly design data acquisition. Typically, a thin high-resistivity membrane is placed underneath the waste to prevent leakage of leachate. In the construction of a numerical framework for sensitivity computation, taking into account the actual dimensions of the electrodes and, in particular, of the membrane, can lead to extremely high computational costs. In this work, we present a novel approach for numerically computing sensitivity effectively by adopting a mixed-dimensional framework, where the membrane is approximated as a two-dimensional object and the electrodes as one-dimensional objects. The code is first validated against analytical expressions for simple four-electrode arrays and a homogeneous medium. Then it is tested in simplified landfill models, where a two-dimensional box-shaped liner separates the landfill body from the surrounding media, and 48 electrodes are used. The results show that electrodes arranged linearly along both sides of the perimeter edges of the box-shaped liner are promising for detecting liner damage, with sensitivity increasing by 2 to 3 orders of magnitude, even for damage as small as one-sixth of the electrode spacing in diameter. Good results are also obtained when simulating an electrical connection between the landfill and the surrounding media that is not due to liner damage. The configurations with the highest sensitivity directly beneath the liner are quadrupoles in which both the current and voltage dipoles have one electrode inside the liner and one electrode outside, and a two-dimensional arrangement of the electrodes. The modelled sensitivity values beneath the liner are close to a minimum sensitivity threshold derived from arbitrary and simplified assumptions. We believe that direct current surveys have the potential to detect liner damage using electrode spreads positioned along the liner perimeter, both inside and outside the landfill. However, down-scaled laboratory tests will be necessary to validate the modelling results and confirm whether the computed sensitivity values are sufficiently high to reliably detect liner damage.</p>","PeriodicalId":12793,"journal":{"name":"Geophysical Prospecting","volume":"73 4","pages":"1212-1227"},"PeriodicalIF":1.8,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/1365-2478.70006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143845794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effect of lamination on elastic anisotropy of primary coals under confining pressure: Experiment and theoretical modelling","authors":"Fei Gong,&nbsp;Jiwei Cheng,&nbsp;Guowei Wang,&nbsp;Suping Peng,&nbsp;Zhaoji Zhang","doi":"10.1111/1365-2478.70009","DOIUrl":"https://doi.org/10.1111/1365-2478.70009","url":null,"abstract":"<p>The deep coalbed methane development is in its initial stage, with limited research on elastic anisotropy of coals in deep coalbed methane reservoirs. To study the elastic anisotropy of coals in deep coalbed methane reservoirs, three sets of cylindrical primary coals are collected from the relatively shallow area of the Taiyuan 8^# coal formation, a key site for deep coalbed methane extraction. The microscopic observation, basic physical property test, ultrasonic velocity measurement and theoretical modelling are constructed to study the pressure sensitivity of elastic properties and the factors affecting the elastic anisotropy of coal samples. The velocity increases rapidly with confining pressure increasing at confining pressures below 13 MPa but relatively stabilizes at higher pressures. The velocity perpendicular to the bedding plane is more sensitive to pressure than that parallel to the bedding plane. As confining pressure increases, the velocity anisotropy decreases but remains noticeable at the highest pressure. Based on the microstructure and ultrasonic experiment results, an anisotropic rock physics model for the deep coalbed methane reservoir is constructed to quantitatively analyse the effects of the clay and organic matter and pore structure on the elastic anisotropy of coals. The modelling analysis indicates that P- and S-wave velocity anisotropies decrease as the degree of preferred orientation of organic matter and clay decreases, which increases with the increase of organic matter and clay content. The equivalent pore aspect ratio and lamination index of studied coals are obtained from a practical inversion scheme based on the proposed model. The results can support the anisotropic rock physics inversion of deep coalbed methane reservoirs and the accurate prediction of engineering sweet spot parameters.</p>","PeriodicalId":12793,"journal":{"name":"Geophysical Prospecting","volume":"73 4","pages":"1228-1242"},"PeriodicalIF":1.8,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143845793","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}

{"title":"On signal contribution functions and sensitivity for frequency-domain electromagnetic and direct current electrical resistivity methods","authors":"S. L. Butler","doi":"10.1111/1365-2478.70011","DOIUrl":"https://doi.org/10.1111/1365-2478.70011","url":null,"abstract":"<p>Signal contribution functions can be integrated over space to calculate the response of an electrical or electromagnetic technique to a given resistivity distribution. On the other hand, sensitivity functions show how the measured signal changes with a change in resistivity in a region of the ground. Signal contribution functions and sensitivity have been previously presented for the direct current resistivity technique. While useful forms of both the signal contribution function and sensitivity are proportional to the correlation of the current densities from the normal and reciprocal configurations, it has not previously been shown how sensitivity can be derived directly from the signal contribution. For frequency-domain electromagnetic techniques, there are existing expressions for sensitivity but not for the signal contribution. In this contribution, I show how the direct current signal contribution can be differentiated to obtain the sensitivity. I also derive an expression for the signal contribution function for frequency-domain electromagnetics and show how it can be differentiated to obtain the sensitivity. The new signal contribution function has a term that, like the sensitivity, is proportional to the electrical current densities from the normal and reciprocal configurations and an additional term that is proportional to the correlation of the magnetic fields from the normal and reciprocal configurations. I show plots of these two terms and investigate their magnitudes as a function of the induction number. This new expression will be useful for testing numerical models and aids in understanding the measured results in frequency-domain electromagnetics.</p>","PeriodicalId":12793,"journal":{"name":"Geophysical Prospecting","volume":"73 4","pages":"979-993"},"PeriodicalIF":1.8,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/1365-2478.70011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143845795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}