Geophysical Interpretation Research Articles

Results of geological and geophysical study of the deep structure of Angara and Trans-Baikal mantle plumes and their connection with mineral deposits.

The purpose of the article is to consider the issues of geological and geophysical interpretation of the data of balloon and satellite magnetic measurements along the regional profile crossing the territory of the Angara-Baikal region. In order to conduct scientific research along the regional Trans-Siberian geological and geophysical profile A-B the author used various geological and geophysical materials including the magnetic field digital data measured by the MAGSAT artificial Earth satellite and a balloon; data on the values of the electrical resistivity in the mantle of this region; geothermal data; seismic data on the location of earthquake hypocenters in the area of the profile under investigation. The research methods involved multilevel measurements of satellite and balloon magnetic fields, which significantly expanded the possibilities of geological and geophysical interpretation of the data obtained. The conducted study revealed that the geological and geophysical interpretation of multilevel aeromagnetic data allows for a reasonably accurate determination of the location coordinates and lithospheric penetration depth of tectonic faults associated with the Angara and Trans-Baikal mantle plumes, which are of significant interest in terms of exploration of coal and uranium deposits. The spatial and depth characteristics of tectonic faults obtained from balloon and satellite data are confirmed by a set of analyzed independent geophysical data: magnetotelluric sounding, geothermy, seismology and other geophysical methods. In conclusion it should be noted that the author has demonstrated the application possibility of satellite and balloon magnetic surveys for the study of the deep structure of the Angara and Trans-Baikal mantle plumes. In addition, it was found out that according to balloon and satellite magnetic data, large deep tectonic faults in the lithosphere (Barguzinsky, Ikatsky, Tukolamsky, Tungirsky) can be identified, which also allow marking various subhorizontal boundaries of lithospheric layers in the location area of the Angara and Trans-Baikal mantle plumes using special points of the magnetically active zones of these faults. The practical significance of the conducted research is in the identification of the spatial relationship between the location of the Angara mantle plume and coal deposits of the Irkutsk basin, as well as uranium deposits in the zone of the Trans-Baikal mantle plume.

GANSim‐3D for Conditional Geomodeling: Theory and Field Application

AbstractWe present a Generative Adversarial Network (GAN)‐based 3D reservoir simulation framework, GANSim‐3D, where the generator is progressively trained to capture geological patterns and relationships between various input conditioning data and output earth models, and is thus able to directly produce multiple 3D realistic and conditional earth models from given conditioning data. Conditioning data can include 3D sparse well facies data, probability maps, and global features, such as facies proportion. The generator only includes 3D convolutional layers, and once trained on a data set consisting of small‐size data cubes, it can be used for geomodeling of 3D reservoirs of large arbitrary sizes by simply extending the inputs. To illustrate how GANSim‐3D is practically used and to verify GANSim‐3D, a field karst cave reservoir in Tahe area of China is used as an example. The 3D well facies data and 3D probability map of caves obtained from geophysical interpretation are taken as conditioning data. First, we create training, validation, and test datasets consisting of 64 × 64 × 64‐size 3D cave facies models integrating field geological patterns, 3D well facies data, and 3D probability maps. Then, the 3D generator is trained and evaluated with various metrics. Next, we apply the pretrained generator for conditional geomodeling of two field cave reservoirs of size 64 × 64 × 64 and 336 × 256 × 96, respectively. The produced reservoir realizations prove to be diverse, consistent with field geological patterns and field conditioning data, and robust to noise in the 3D probability maps. Each realization with 336 × 256 × 96 cells only takes 0.988 s using 1 GPU.

High-resolution imaging of subsurface infrastructure using deep learning artificial intelligence on drone magnetometry

The use of drones fo r geophysical data acquisition and artificial intelligence (AI) for geophysical data processing, imaging, and interpretation are active focus areas in current industry and academic applications. Unlocking their cumulative potential in single-focus applications can have a transformative impact, possibly leading to dramatic cost reductions in key use cases and new application areas for enhanced actionable business intelligence. We present field study results from Texas and California that show the potential for imaging pipelines and other subsurface infrastructure by using AI-based methods on high-resolution aboveground magnetic data. The superior resolution and interpretability over conventional geophysical inversion is demonstrated. The method has the potential to provide actionable intelligence in several business-use cases for detecting and characterizing pipelines, crossing zones for multiple pipes, etc. at dramatically reduced costs. The advanced algorithms and workflows used resulted in a 100-fold increase in efficiency and delivered results in two days compared to what could take several months using generally available open-source deep learning AI workflows and software. Future direction of development is to validate against excavation-/drill-bit-/inline-tool-based ground truth and further extend and develop this process to deliver near real-time results. The techniques used are general and can be applied to other geophysical data including seismic, electromagnetic, and gravity at various scales and resolution.

Seismic interpretation and hydrocarbon assessment of the post-rift Cenomanian Bahariya reservoir, Beni Suef Basin, Egypt

The geophysical interpretations for a collection of high-quality 2D seismic data plus well logging data for six drilled wells exposed the structural controls and the hydrocarbon potentiality of the Beni Suef Basin, north Western Desert, Egypt. The created structural map on the top of the Early Cenomanian Bahariya Formation (the significant oil reserve in north Western Desert), exhibits a series of NW–SE normal faults as well as a master ENE strike-slip major fault. The extensional faults formed horst structures while the strike-slip fault created a negative flower structure in the central part of the study area. These structural features represent the main petroleum traps within Beni Suef Basin. The reservoir quality was assessed through the petrophysical analysis of the Bahariya Formation in wells; Azhar A2, Azhar E-2X, Azhar E3, Yusif-4X, Fayoum-2X and Beni Suef W-1X. This analysis proved that the Lower Bahariya unit has better reservoir quality than the Upper Bahariya reservoir, with shale volume less than 10%; effective porosity between 10 and 20%, water saturation between 25 and 75% and total pay thickness between 11 and 88 ft. The obtained results encourage drilling more exploratory wells in Beni Suef Basin to enhance the productivity from the sandstones of the Lower Bahariya reservoir.

Geothermal Mechanism and Reservoir Characterization with Multiscale Analysis of the Potential Field and MT Profile in the Yanqing-Huailai Basin, North China

Abstract Geothermal energy has attracted increasing attention worldwide due to its abundant reserves, stability, and sustainability. Based on the survey of geothermal resources in the Yanqing-Huailai Basin, this paper conducts comprehensive data study, demonstrates geothermal distribution and multiscale characteristics, and constructs the geothermal mechanism and conceptual model to promote regional geothermal energy development and utilization. Our study proposes to characterize geothermal reservoirs using geophysical data ranging from the representative geothermal field scale to the basin scale. Hydrochemical samples were also collected. According to the results of multiscale analysis and interpretation, combined with field geological and geothermal investigations, it is concluded that the Dahaituo pluton is composed of acid granite and monzonite granite, with low gravity and high magnetic anomaly. Its intrusion and development are responsible for the local geothermal anomaly. Multiscale analysis and source depth estimation of potential field data and MT profile interpretation were carried out. The regional thermal structure and reservoir characteristics were demonstrated from the deep to the shallow. In addition, according to the regional geological background and geophysical interpretation, a three-dimensional geological model is constructed to characterize the distribution law and genetic mechanism of geothermal anomalies. The study shows that strong Cenozoic tectonic movement and the intrusion and development of rock mass are the main factors causing local geothermal anomaly. The development of regional deep and major faults and extensional structures, as well as the channels and space formed by the breaking of rocks at the intersection of faults, provides advantageous conditions for the upwelling, migration, and convergence of geothermal fluids. The recharge of surface water in the intermountain basin and thermal convection drive the circulation of the geothermal system.

Magnetic prospecting and rock magnetic study of soils and archaeological objects on the Late Roman time sites near Komariv in Middle Transnistria

The paper presents the outcome of the magnetic survey at the settlement and cemetery of the production center of the 3rd—5th centuries, Komariv (Khotyn district, Chernivtsi region), which is located on the right bank of the Dniester. The settlement has about seventy anomalies that may have an archaeological origin. The archaeological study of individual anomalies has confirmed, as expected, the reliability of geophysical interpretation of thermal structures (kilns, furnaces) and living and production dugouts deepened into the loess parent rock. Magnetic imaging at the cemetery showed about eight tens of local anomalies with an intensity of 1.5—4.5 nT. Excavations of some anomalies revealed the Early Iron Age dugout and two Late Roman graves. However, the other two excavated graves did not cause disturbance of magnetic field. Laboratory measurements of magnetic susceptibility, natural remanent magnetization and other concentration-dependent and grain-size-dependent parameters of the ferromagnetic phase, as well as magnetic mineralogy examination have shown that grave pits, which appeared on a magnetic map, are refilled almost exclusively with humus soil material. Magnetic modeling proved graves can create measured anomalies if their magnetization is equal to the magnetization of the humus horizon of the soil. Thus, these grave pits were left open and gradually refilled with moist soil material. In particular, conditions have been created for the formation of detrital remanence. When restoring the spatial structure of Komariv sites based on magnetic prospecting results, it is necessary to take into account probable multilayered structure of monuments, geomorphological features of the area, which can be misinterpreted as archeological objects, and the fact that important examples of ancient architecture constructed of non-magnetic materials and grave pits refilled immediately after digging will be absent on magnetic maps.

Tectonic domains in the NW Amazonian Craton from geophysical and geological data

The Amazonian Craton is one of the largest cratonic areas in the world. In Colombia, a major portion of the Craton is covered by Paleozoic to Cenozoic sedimentary rocks and recent deposits. This, in addition to the difficulty of access and dense tropical rainforest, have made the geology of this area to remain relatively unexplored to this date. Most accepted models for the Proterozoic evolution of the Amazonian Craton indicate that it evolved via successive accretion of orogenic belts and crustal terranes around an ancient nucleus, and that tectonic provinces identified in the southern half of the craton, the Guaporé Shield, extend underneath the Amazon River Basin onto its northern exposure, the Guiana Shield. Nevertheless, recent geologic studies in the W Guiana Shield indicate that its evolution may have been different from the W Guaporé Shield, where these accretionary models were formulated. In this work, we used airborne gravity/magnetic geophysical datasets covering the NW portion of the Amazonian Craton, to better elucidate its structure and tectonic evolution. We apply a multiscale edge detection and 3D modeling to identify and delineate major crustal discontinuities and other geological features. Using this approach, we identified six primary geophysical lineaments that are interpreted as possible crustal boundaries. By combining our geophysical interpretation with all the geological, geochronologic and isotopic information available for the region, we propose the presence of the following tectonic domains: Ventuari-Tapajós, Rio Negro-Juruena (which we further subdivide into Atabapo and Vaupés Belts), Apaporis Graben, and Putumayo. Furthermore, a new U-Pb zircon crystallization age of 1227 ± 8/13 Ma obtained from volcanic rocks of the Piraparaná Formation indicates that extensional tectonics along the Apaporis Graben began at least in the late-Mesoproterozoic. This is significantly older than previously thought, and thus entirely transforms the tectonic significance of the Apaporis Graben structures. Our interpretation of structural limits is in excellent agreement with and provides a more accurate location for previously suggested boundaries, which were until now only loosely constrained by the sparse geological and geochronologic information available. This work provides the first regional reconstruction of crustal-scale features of NW South America, improving the understanding of the regional tectonic architecture of NW Amazonian Craton using geophysical methods.

Natural radioactivity assessment and geophysical interpretation of parts of Igarra area, Southern Nigeria.

To evaluate the concentration of natural radionuclides and to carry out geophysical interpretation of part of Igarra area, Southern Nigeria, an integrated geophysical approach was adopted involving radiometric, gravity, and magnetic methods. The RS-230 Super-Spec spectrometer, G-512 Lacoste and Romberg gravimeter, and the GSM-19v7.0 Overhauser instrument were used for the radiometric, gravity, and magnetic data acquisitions, respectively, along a specified traverse within the area. The datasets were processed using Oasis Montaj, Grav-Master, and Ms-Excel software. Gravity results show that the mean free air and Bouguer anomalies in the area are - 67.42 and - 84.22 mGal, while magnetic survey indicates that the mean corrected magnetic field intensity in this area is 32218.49 nT. Radiometric survey results show that the mean radioactivity concentrations of thorium ([Formula: see text], uranium ([Formula: see text]), and potassium ([Formula: see text]) are 31.81Bq/kg, 26.48Bq/kg, and 167.33Bq/kg, respectively. Further analysis also revealed that the mean radioactivity equivalent of the area is 84.86Bq/kg; absorbed dose rate is 72.74nGy/h, while the mean external hazard index is 0.30. A novel model equation for estimating absorbed dose rate from radioactivity equivalent was also obtained and validated. The gravity and magnetic survey results indicate the presence of low-density and high magnetic basement rocks underlying this area, while radiometric results reveal that radiations in this area did not exceed acceptable standards of 370Bq/kg for radioactivity equivalent, 84 nGy/h for absorbed dose rate, and unity which corresponds to 370Bq/kg for external hazard index as recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation and the International Atomic Energy Agency.

Automated Hierarchical 3D Modeling of Quaternary Aquifers: The ArchPy Approach

When modeling groundwater systems in Quaternary formations, one of the first steps is to construct a geological and petrophysical model. This is often cumbersome because it requires multiple manual steps which include geophysical interpretation, construction of a structural model, and identification of geostatistical model parameters, facies, and property simulations. Those steps are often carried out using different software, which makes the automation intractable or very difficult. A non-automated approach is time-consuming and makes the model updating difficult when new data are available or when some geological interpretations are modified. Furthermore, conducting a cross-validation procedure to assess the overall quality of the models and quantifying the joint structural and parametric uncertainty are tedious. To address these issues, we propose a new approach and a Python module, ArchPy, to automatically generate realistic geological and parameter models. One of its main features is that the modeling operates in a hierarchical manner. The input data consist of a set of borehole data and a stratigraphic pile. The stratigraphic pile describes how the model should be constructed formally and in a compact manner. It contains the list of the different stratigraphic units and their order in the pile, their conformability (eroded or onlap), the surface interpolation method (e.g., kriging, sequential Gaussian simulation (SGS), and multiple-point statistics (MPS)), the filling method for the lithologies (e.g., MPS and sequential indicator simulation (SIS)), and the petrophysical properties (e.g., MPS and SGS). Then, the procedure is automatic. In a first step, the stratigraphic unit boundaries are simulated. Second, they are filled with lithologies, and finally, the petrophysical properties are simulated inside the lithologies. All these steps are straightforward and automated once the stratigraphic pile and its related parameters have been defined. Hence, this approach is extremely flexible. The automation provides a framework to generate end-to-end stochastic models and then the proposed method allows for uncertainty quantification at any level and may be used for full inversion. In this work, ArchPy is illustrated using data from an alpine Quaternary aquifer in the upper Aare plain (southeast of Bern, Switzerland).

Tectonophysics Perspectives on Integrated, Coordinated, Open, Networked (ICON) Science

AbstractThis article is composed of two independent opinion pieces about the state of integrated, coordinated, open, and networked (ICON) principles (Goldman et al., 2021, https://doi.org/10.1029/2021EO153180; Goldman et al., 2022, https://doi.org/10.1029/2021ea002099) in Tectonophysics and discussion on the opportunities and challenges of adopting them. Each opinion piece focuses on a different topic: (a) global collaboration, technology transfer and application, reproducibility, and data sharing and infrastructure; and (b) field, experimental, remote sensing, and real‐time data research and application. Within tectonophysics science, ICON‐FAIR principles are starting to be adopted and implemented, however they have not become frequent and there are still plenty of opportunities for further development. During the last decade, standardization reduced fragmentation, facilitated openly available databases, and enabled different modeling methods to be combined. On the other hand, integration and coordination remained insufficient as exemplified by numerous geophysical interpretation programs running on different platforms, lacking the proper documentation and with diverse output formats. We agree that adapting the principles of ICON‐FAIR brings high efforts and risks, but in the end, it has great benefits and potential in the tectonophysics community.

Detecting resistivity and induced polarization anomalies of galena veins in the presence of highly chargeable and conductive geological units at Daryan barite deposit in Iran

Assessment of resistivity and induced polarization (IP) data for metallic sulfide ore explorations is considered a routine task in the mining industry. The success in these surveys would be challenging if the sulfide ore lies within conductive and chargeable geological units. In this study, the resistivity and IP data of the Daryan area in northwestern Iran were examined for the detection of high-grade galena veins hosted by the Kahar Formation, a complex geological formation with several conductive and chargeable geological units. To facilitate the geophysical interpretations, a simple approach was adopted to solve the problem, and it was shown that a combination of correct geophysical modeling and approximate clustering of physical properties can help to check and revise (if necessary) the geological model or geophysical interpretations. In the Daryan area, the barite mineralization had high resistivity and low IP anomalies. More importantly, it was found that the highest IP and the lowest resistivity values were not the responses of galena mineralization but the graphite-rich shale. Thus, in complicated situations, the data should be treated and interpreted carefully because the “rules of thumb” may not work. This fact highlighted that prioritization of anomalies based on geophysical models alone is not an appropriate strategy in mineral exploration, and the interpretations must always be evaluated with geology. Moreover, it was discussed that both volume concentration and style of conductive minerals can be vital for creating elusive electrical responses, thus caution should be taken while interpreting electrical models in areas with complicated geology.

Probing the Southern African Lithosphere With Magnetotellurics: 2. Linking Electrical Conductivity, Composition, and Tectonomagmatic Evolution

AbstractThe tectonic history of southern Africa includes Archean craton formation, multiple episodes of subduction and rifting and some of the world's most significant magmatic events. These processes left behind a compositional trail that can be observed in xenoliths and measured by geophysical methods. The abundance of kimberlites in southern Africa makes it an ideal place to test and calibrate mantle geophysical interpretations that can then be applied to less well‐constrained regions. Magnetotellurics (MT) is a particularly useful tool for understanding tectonic history because electrical conductivity is sensitive to temperature, bulk composition, accessory minerals, and rock fabric. We produced three‐dimensional MT models of the southern African mantle taken from the SAMTEX MT data set, mapped the properties of ∼36,000 garnet xenocrysts from Group I kimberlites, and compared the results. We found that depleted regions of the mantle are uniformly associated with high electrical resistivities. The conductivity of fertile regions is more complex and depends on the specific tectonic and metasomatic history of the region, including the compositions of metasomatic fluids or melts and the emplacement of metasomatic minerals. The mantle beneath the ∼2.05 Ga Bushveld Complex is highly conductive, probably caused by magmas flowing along a lithospheric weakness zone and precipitating interconnected, conductive accessory minerals such as graphite and sulfides. Kimberlites tend to be emplaced near the edges of the cratons where the mantle below 100 km depth is not highly resistive. Kimberlites avoid strong mantle conductors, suggesting a systematic relationship between their emplacement and mantle composition.

Novel methodology for the geophysical interpretation of magnetic anomalies due to simple geometrical bodies using social spider optimization (SSO) algorithm

The inefficiencies and uncertainties surrounding solutions from existing inversion methods have necessitated investigation for more efficient techniques for the inversion of ill-posed magnetic problems. In this study, the Social Spider Optimization (SSO) algorithm has been modified, adopted and successfully used in modelling physical characteristics of magnetic anomalies originating from simple-shaped geologic structures. The study, aimed at testing the capacity and efficiency of the SSO algorithm to model magnetic data of varying complexity, was successfully conducted on both synthetic data with varying levels of noise and real field data obtained from mining fields in Senegal and Egypt. To assess the mathematical nature of the inverse problem considered, error energy maps were produced for each model parameter pairs in the synthetic examples. These maps enabled the pre-assessment of the resolvability model parameter for the ill-posed problem. In addition, uncertainty analysis aimed at providing insight to the reliability of the obtained solutions was carried out using the Metropolis–Hastings (M–H) sampling algorithm. Results show that the procedure converges fast and generates accurate results even when confronted with constrained multi-parameter non-linear inversion problems. Its outstanding converging speed and accuracy of the results reveal it as an excellent procedure for overcoming agelong problems of local optimal solutions associated with pre-existing algorithms. The consistency of the results with actual values affirms the efficacy of the new procedure which is pioneering in geophysical literature. It is therefore a stable and efficient tool for performing geophysical data inversion and is therefore recommended for use in inverting geophysical data with higher complexities like seismic reflection and gravity data, that require many corrections to be performed before reliable geological interpretations can be made.

Petrophysics applied in mineralizations, hydrothermal alterations and lithology mapping: A case study from the Zn–Pb (Cu–Ag) epithermal deposit of Santa Maria, Brazil

ABSTRACTThe epithermal Zn–Pb (Cu–Ag) deposit of Santa Maria represents a distal magmatic‐hydrothermal system, whose mineralizations are controlled by fault systems located in the sedimentary units of the upper Camaquã Basin, above the tectonic units of the Sul‐Riograndense Shield. The hydrothermal alteration zones contain illite, chlorite and pyrite, besides galena, sphalerite, chalcopyrite and bornite. To improve the knowledge of this mineral system, this work investigated the petrophysical footprints of samples representing the predominant lithology, altered rocks and hydrothermal mineralization. The core samples of the predominant lithology, altered rocks and hydrothermal deposit mineralizations were used to determine the following petrophysical properties, density, magnetic susceptibility, primary wave velocity, resistivity, conductivity and chargeability. Moreover, the quantitative evaluation of minerals by scanning electron microscopy coupled with an automated image analysis system allowed us to map lithological and alteration processes. The results indicate density as the most effective physical property to map lithology, hydrothermal alteration and the Zn–Pb (Cu–Au) mineralization. Furthermore, all studied physical properties have moderate effectiveness in the alteration zones of known geological and geophysical anomalies in the Santa Maria deposit. Chargeability could be used, especially when sulphides are disseminated, but additional geological factors complicate its interpretation. The mineralogical and petrophysical diversity of the Santa Maria deposit provided vital data for geological–geophysical interpretations while allowing the creation of a key exploration plan to investigate the Zn–Pb (Cu–Au) mineralization. Finally, petrophysics should be used in prospection to help understand complex geological processes, their overlapping subpopulations and to accelerate mineral research while reducing the use of technical and financial resources and expenditure on ineffective geophysical methodologies.

Further Development of Studies of Pressure Fields in the Arctic Region of Russia

The results of studies of atmospheric pressure in the Arctic region of Russia in the period from 1948 to 2008 are presented. The analysis of the climatic seasonal variation of the atmospheric pressure fields is carried out. As the main research method, the probabilistic and statistical analysis of the time series of the pressure field 60 years long at fixed points in the region of the Arctic zone of Russia was used. In total, about 90,000 daily (in six-hour increments) pressure values were examined. On the basis of these data, a climatic seasonal variation was constructed as an averaging of the values of a given time series at each point in space and for a fixed date. The characteristics of the seasonal course, its amplitude and phase have been studied. These characteristics were analyzed and their geophysical interpretation was carried out. In particular, the minimum and maximum values ​​of the series were determined for the entire region and the time series of these characteristics were constructed. It is shown that the deviation is asymmetric, this is an unobvious research result. For the maximum and minimum, the best approximations were constructed, and these approximations were tested by known methods of statistical analysis, including maximum likelihood, least squares and goodness of fit methods (tests), in particular, the χ2-criterion. The conducted research has applications both purely physical (allows to explain the nature, genesis and distribution of large-scale atmospheric formations in a climatic year) and prognostic (allows understanding and tracking trends in climate, as well as quantitatively assessing the scale and variability of large-scale atmospheric processes). Numerical calculations were performed on the Lomonosov-2 supercomputer of the Lomonosov Moscow State University.

Improvement of Seismic Sections and Well Logs for Joint Geophysical Interpretation

Seismic and well-logging data are useful for comparison and then integratation for a comprehensive geophysical interpretation. In the course of this work, seismic results were compared with well-logging geophysical data and profiles for more reliable evaluation of groundwater formations in the Tokaj region, north-east Hungary. The seismic results and profiles were obtained by the Common Reflection Surface (CRS) stacking technique. This is an advantageous stacking technique that is expected to greatly improve seismic profiles. In connection with this, we also examined some well-logging geophysical profiles so that we can improve later results. By comparing and examining the two types of sections together, we provide a basis for various method developments that improve the sections. Thus, the aim is to fill in the missing data, so that the well-logging and seismic sections can be examined together as accurately as possible in order to gain a more accurate picture of the subsurface formations. It is important to determine the lithology and petrophysical characteristics using well logs. The section replacement the improvement of the units is done using machine learning-based and inversion methods such as factor analysis or cluster analysis. An important outcome in the application of geophysical inversion methods is that the results of different methods can be jointly interpreted and this can significantly increase the reliability of the results. The application of these methods and their development is expected to reduce uncertainty and ambiguity and to increase the accuracy of the sections.

Autofocus-Based Estimation of Penetration Depth and Permittivity of Ice Volumes and Snow Using Single SAR Images

An intrinsic challenge in the geophysical interpretation of low-frequency synthetic aperture radar (SAR) imagery of semitransparent media, such as ice sheets, is the position ambiguity of the scattering structures within the glacial volume. Commonly tackled by applying interferometric and tomographic techniques, their spaceborne implementation exhibits by orders higher complexity compared to missions relying on single SAR images, making them cost expensive or, in the context of planetary missions, even impossible due to limited navigation capability. Besides, even these sophisticated techniques are commonly biased due to inaccurate permittivity estimates, leading to geometric distortions up to several meters. We present a novel inversion procedure to estimate volume parameters of ice sheets, namely, the depth of the scattering layer within the glacial volume and the dielectric permittivity of the ice, based on single-image single-polarization SAR acquisitions. The information is inherent in the processed SAR data as phase errors on the azimuth signals resulting from uncompensated nonlinear propagation of the radar echoes through ice. We suggest a local map-drift autofocus approach to quantify and spatially resolve the phase errors and an inversion model to relate them to the penetration depth and permittivity. Testing the proposed technique using P-band SAR data acquired using DLR’s airborne sensor F-SAR during the ARCTIC15 campaign in Greenland shows promising results and good agreement with tomographic products of the analyzed test site.

Bridging the Gap Between Geophysics and Geology With Generative Adversarial Networks

Inverse mapping from geophysics to geology is a difficult problem due to the inherent uncertainty of geophysical data and the spatially heterogeneous patterns (structure) in geology. We improve conditional facies simulation based on GANs (GANSim), a new Earth model simulation method based on generative adversarial networks (GANs), to bridge the gap between remotely sensed geophysical information and geology, by introducing a specially designed loss function and an input architecture for probability maps representing geophysical interpretation. After training, the GANSim is then used to produce multiple geological facies models conditioned to the input geophysics-interpreted probability maps alone or together with input well observations and global features. By evaluation, the generated facies models are realistic, diversified, and consistent with all input conditions. We demonstrate that the GAN learns the implicit geological pattern knowledge from the training data set and the knowledge of conditioning to inputs from human-defined explicit functions. Given the commonality of remotely sensed geophysical information, sparse measurements, and global features, GANSim should be applicable to many problems of geosciences.

New Evidence of the Holokinetic Sequences around Suakin-1 and -2in the Sudanese Red Sea Area Using Integrated Geophysical Interpretation

Suakin-1 and Suakin-2 wells are in the Sudanese Red Sea segment where the hydrocarbon generation had been proved by previous studies, however, no reasonable reserve was evidenced due to the complexities of the surrounding salt structures. Six seismic lines were tied to Suakin-1 and -2 to delineate the controlling salt tectonics. The salt evacuation (Roho) and other salt bodies were recognized and matched with similar salt structures in analogous stratigraphic conditions as the Gulf of Mexico and Angola margin. While a previous inconsistent interpretation in the study area marked the high amplitude horizon of the Lower Zeit formation as the top of the Dungunab formation. Three seismic features indicated the presence of salt dome (autochthonous): velocity pull-up, dragging of the sedimentary layers forming mini basins around the third feature, which is the relative transparency of the seismic signal in two piercing like bodies. This interpretation similarly demarcated that the salt escaped east-wards, thus the mapped welded salt is believed to be formed after the salt evacuation. A 3D seismic with a far offset and wide range of azimuth is recommended for detailed imaging.

Geophysical interpretation methods' improvement of Bilche-Volytska zone of Pre-carpathian foredeep complex geological cross-sections' comprehensive research results

The article considers the problem related to the ambiguity of logging results, which is reflected in the reduction of the efficiency of certain interpretive methods, and as a consequence of oil and gas reservoirs omission. In this regard, the analysis of the results of gamma logging, spontaneous polarization methods, nuclear magnetic logging, were conducted. The received information of experimental researches of cores, has allowed establishing the reasons of distortion of radioactive and electric logging indications which considerably influence on size of radioactive and electric fields intensity. In addition, the efficiency of gamma-spectrometric method and nuclear magnetic resonance is substantiated. It is established that the matrix of rocks of Neogene sediments contains minerals of sulfides, oxides, which include iron, copper, aluminum. That determines the electronic conductivity of oil and gas saturated layers. Different from clarke, the contents of uranium, thorium and potassium were determined in the matrix of the above mentioned rocks according to the results of gamma spectrometry. These elements affect the value of the natural intensity of hydrocarbon-saturated rocks’ radioactive field. A method for determining the carke content of radioactive isotopes of uranium, thorium and potassium with the calculation of their ratio was developed to unambiguously assess the nature of the increased radioactivity of Neogene rocks. The results justify the use of the latest technological methods for gamma spectrometry and nuclear magnetic resonance in the allocation of productive rocks. Well research by NMR can be effectively performed with the help of NMLE-3 (nuclear magnetic logging equipment), and gamma spectrometry can be conducted with the help of SGSM-2.