Search

Each nuclear weapon test contributes to a global burden of released radioactivity. Between 1945 and 1996, more than 2,000 nuclear tests were conducted, three-quarters of which were underground. Underground nuclear tests involved placing the nuclear device in a cavity drilled or excavated beneath the surface. The goal was to contain the explosion and its effects to the immediate vicinity of the detonation point, ultimately minimizing the release of radioactive materials into the atmosphere. While these tests successfully curtailed the atmospheric release and radioactive fallout, they created dynamic responses within crustal formations caused by local shock waves from the explosion. This paper discusses the legacy of underground nuclear testing, addressing issues from containment failure to the phenomenological effects after underground detonations and the pathways of subsequent dispersal of radionuclides to the environment. [ABSTRACT FROM AUTHOR]

H2 produced from renewable energies will play a central role in both greenhouse gas reduction and decarbonization by 2050. Nonetheless, to improve H2 diffusion and utilization as a fuel, large storage capacity systems are needed. Underground storage of natural gas in depleted reservoirs, aquifers and salt caverns is a well-established technology. However, new challenges arise when it comes to storing hydrogen due to the occurrence and activity of indigenous microbial populations in deep geological formations. In a previous study, four Italian natural gas reservoirs were characterized both from a hydro-chemical and microbiological point of view, and predictive functional analyses were carried out with the perspective of underground hydrogen storage (UHS). In the present work, formation waters from the same reservoirs were used as inoculant during batch cultivation tests to characterize microbial activity and its effects on different gas mixtures. Results evidence a predominant acidogenic/acetogenic activity, whilst methanogenic and sulfate reducing activity were only marginal for all tested inoculants. Furthermore, the microbial activation of tested samples is strongly influenced by nutrient availability. Obtained results were fitted and screened in a computational model which would allow deep insights in the study of microbial activity in the context of UHS. [ABSTRACT FROM AUTHOR]

Here, the prediction of friction characteristics for pipe jacking drives during soil traversing has been explored. This work is done in the context of no great understanding of how drivers negotiate highly weathered rock formations. Based on a series of jacking force prediction models, including the Staheli model, Pellet-Beaucour and Kastner models (PK-O models) and proposed modified Pellet-Beaucour and Kastner models (PK-M models), direct shear tests are performed on initial-contacted specimens to obtain the friction coefficient μavg using back-analysis. The evaluation of the reliability of the parameter μavg and the modified vertical pressure σv is carried out through a three-dimensional finite element in ADINA in combination with the "wished-in place" method (WPM). The shear stress of the pipe–rock interface and the compressive stress of the end area are obtained by numerical analysis and in good agreement with the measured jacking force predicted by the proposed PK-M-1 model, indicating the correctness and necessity of considering the degree of the arching effect when modeling strong weathering rock masses. According to these results, the friction coefficient μavg of back-analysis can be used as a reliable input parameter for the finite-element modeling of pipe-jacking force in highly weathered geological formations. Highlights: The modified Pellet-Beaucour and Kastner models (PK-M models) have been established. A modified simulation method for rock pipe jacking in highly weathered rocks has been studied in ADINA. The correctness and superiority of the PK-M models have been discussed and verified. [ABSTRACT FROM AUTHOR]

A total of 66,894 landslides were observed in North Dakota. The characteristics of these landslide locations were compared with the properties of areas without landslides to assess the factors that may be contributing to the landslides. Specifically, 68,395 control point locations randomly distributed across the state were selected for these comparisons. All the landslides for this study were found in areas with slopes less than 64°, with the majority of the failures occurring on slopes with inclinations between 9° and 14°. The largest fraction of the landslides occurred in the Sentinel Butte Formation (34,063 or 51% of the total), followed by Bullion Creek (8695 or 13% of the total) and river sediment of the Oahe Formation (6421 or 9.6% of the total). In the t tests, all of the surficial geologic formations had statistically significant differences between the landslides and control points. The t test for the slope inclination indicated statistically significant differences with a p-value less than 0.001 and a huge effect size between the landslide and control points. The sodium adsorption ratio and total dissolved solids were also found to be statistically significant from the t test results. Pearson's correlation matrix showed a negative correlation between the amount of rainfall and various measures of the salt concentrations at the landslide locations, pointing to the reductions in shear strength and slope stability that might result as pore fluid salinity is leached. [ABSTRACT FROM AUTHOR]

The central Sichuan Basin, located in western China, holds great significance in terms of hydrocarbon production, especially in relation to complex carbonate reservoirs, notably the Qixia Formation of the Middle Permian epoch. However, the comprehensive evaluation of this geological formation presents considerable challenges due to complex lithology, limited availability of reservoir property data at various scales, inadequacies in data integration, and the absence of a reliable reservoir ranking system for development decision making. Previous studies primarily relying on conventional data at the reservoir level, such as well logs and geological information, have proven insufficient in accurately characterizing the reservoir. This is especially evident without precise lithological information and detailed knowledge of microscale properties, which are crucial for effective reservoir evaluation. To address these challenges, this study integrates advanced technologies like X-ray diffraction, micro-CT and scanning electron microscope (SEM) techniques in digital drill cutting analysis at the microscale. A novel scoring system has been developed using a prominent component analysis (PCA) approach and an expert scoring system, which incorporates existing conventional well log data and digital cutting analysis. This scoring system has been validated using actual production data, thus establishing a robust evaluation methodology for assessing the exploration potential and optimizing development strategies for carbonate gas reservoirs in the Qixia Formation. The innovative approach, which incorporates parameters at both micro- and macroscales, holds promising potential in facilitating future exploration and development efforts. [ABSTRACT FROM AUTHOR]

Carbon capture and storage technologies play a crucial role in mitigating climate change by capturing and storing carbon dioxide emissions underground. Saline aquifers, among other geological formations, hold promise for long-term CO2 storage. However, accurately assessing their storage capacity and CO2 behavior underground necessitates advanced numerical simulation and modeling techniques. In this study, we introduce an approach based on a solubility thermodynamic model that leverages cubic equations of state offline from the simulator. This approach enables the precise prediction of CO2–brine equilibrium properties and facilitates the conversion of compositional data into black oil PVT data suitable for black oil simulations. By incorporating industry-scale saline aquifer properties, we simulate a carbon storage scheme using the black oil model technique, significantly reducing computation time by at least four times while preserving the essential physical phenomena observed in underground carbon storage operations. A comparative analysis between black oil and compositional simulations reveals consistent results for reservoir pressure, CO2 saturation distributions, and mass fraction of trapping mechanisms, with differences of less than 4%. This validation underscores the reliability and efficiency of integrating the black oil model technique into carbon storage simulations in saline aquifer formations, offering tangible benefits to industry operators and regulators by striking a balance between accuracy and efficiency. The capability of this approach to extend to temperatures of up to 300 °C and pressures of up to 600 bars broadens its applicability beyond conventional CCS applications, serving as a valuable tool for optimizing decision-making processes in CCS projects, particularly in scenarios where profitability may be marginal. [ABSTRACT FROM AUTHOR]

The growth of the geothermal industry demands the constant search of techniques with the aim of reducing exploration efforts whilst minimizing subsurface uncertainty. The exploration of geothermal resources is fundamental from the exploitation point of view, especially in those regions where this energy is not as widespread as the rest of renewable sources. This research shows how geoelectrical methods can contribute to the investigation and characterization of medium–low enthalpy geothermal resources until about 800 m of depth. A 2000 m long electrical-resistivity tomography profile was performed in a region of Southern Spain with previous evidence of moderate geothermal potential. Results of this geophysical campaign (together with a preliminary geological characterization) allowed for the obtainment of a 2D profile and a pseudo-3D model with extensive information about the subsoil in terms of geological composition and formations. The interpretation of geophysical results denotes the existence of a potential formation constituted by carbonate materials with thickness greater than 300 m, crossing different fractures. Once the ideal location for the geothermal exploitation is defined, the research evaluates the contribution of the possible energy source, deducing that the energy extraction in the potential fracturing area would be double that of the one in the vicinity of the site. [ABSTRACT FROM AUTHOR]

Geological hazards in Xinxian County, Xinyang City, Henan Province, are characterized by their small scale, wide distribution, and significant influence from regional tectonics. This study focuses on collapses and landslide hazards within the area, selecting twelve evaluation factors: aspect, slope shape, normalized difference vegetation index (NDVI), topographic relief, distance from geological structure, slope, distance from roads, land use cover type, area of land change (2012–2022), average annual rainfall (2012–2022), and river network density. Utilizing data from historical disaster sites across the region, the information quantity method and hierarchical analysis method are employed to ascertain the information quantity and weight of each factor. Subsequently, a random forest model is applied to perform susceptibility zoning of geological hazards in Xinxian County and to examine the characteristics of these geological disasters. The results show that in the study area, the primary factors influencing the development of geohazards are the distance from roads, rock groups, and distance from geological structure areas. A comparison of the susceptibility results obtained through two methods, the analytic hierarchy process information quantity method and the random forests model, reveals that the former exhibits a higher accuracy. This model categorizes the geohazard susceptibility in the study area into four levels: low, medium, high, and very high. Notably, the areas of very high and high susceptibility together cover 559.17 km2, constituting 35.99% of the study area's total area, and encompass 57 disaster sites, which represent 72.15% of all disaster sites. Geological hazards in Xinxian County frequently manifest on steep canyon inclines, along the curved and concave banks of mountain rivers, within watershed regions, on gully inclines, atop steep cliffs, and on artificially created slopes, among other sites. Areas with very high and high vulnerability to these hazards are mainly concentrated near the county's geological formations. The gneiss formations are widely exposed in Xinxian County, and the gneisses' strength is significantly changed under weathering, which makes the properties of the different degrees of weathering of the rock and soil bodies play a decisive role in the stability of the slopes. This paper provides a basis for evaluating and preventing geologic hazards in the Dabie mountainous area of the South Henan Province, and the spatial planning of the national territory. [ABSTRACT FROM AUTHOR]

• Mapping lithounits of Nidar ophiolites using high-resolution multi-spectral data. • First time characterization of Nidar ophiolites using hyperspectral (PRISMA data) • ML based classification of Nidar Ophiolite & associated rock exposures. • Spectral characterisation of lithounits of Ophiolites and validation from field. Ophiolites represent s a distinctive variety of igneous rock that comprises fragments of oceanic crust with the underlying mantle portion. Their mineral assemblages and distribution relation, both spatial and temporal are in close association with the complex mantle dynamics of the Earth. Nidar ophiolite complex located towards SE of Ladakh is one of such ophiolite assemblages exposed well in the Indus Suture Zone of Himalayas. It represents parts of Neo-Tethys ocean that existed during Mesozoic-Cenozoic period between continental plates of India and Eurasia. The earlier studies for Indian ophiolites are mostly field and analytical based with a limited work carried out using remote sensing techniques and that adds scope to apply this approach for further exploration of ophiolites. Advanced tools and techniques especially, hyperspectral remote sensing and machine learning based approach can be effective operational tools for exploration of ophiolites that provide assessable terrains for characterization of Earth's mantle, serve analogs for planetary crustal rocks and also have economic significance. This study has utilized high-resolution multispectral (Landsat OLI and ASTER) and hyperspectral data from various missions including the recent PRISMA mission which has provided the first hyperspectral datasets for lithological mapping of Nidar ophiolite section. The multiple high-resolution datasets were used for identification and mapping of the various lithounits of the Nidar ophiolites together with the underlying and overlying associated rocks based on band ratioing, derived spectral compositional indices and spectral characterization. The differentiated lithounits of the Nidar ophiolites are interpreted based on spectral response of lithological units in different bands. In addition, classification based on machine learning techniques have been applied to the PRISMA data to generate a detailed classification map of the study area where the various lithological units of the ophiolites and associated rock exposures belonging to various geological formations are clearly discernible. The results have been validated from geological field visit to the study area and spectral analysis of the field samples. [ABSTRACT FROM AUTHOR]

The present study aims to evaluate the groundwater quality in an area characterized by significant human anthropic activities within the upper Seybouse. In order to assess the quality, a total of 20 samples were analyzed to identify the chemical and bacteriological composition of the water, its variations, and their potential impacts on the environment and human health. The results revealed concentrations of the chemical and bacteriological elements exceeding the WHO standards, with high levels of electrical conductivity (EC) (peak = 4210 μS/cm), Ca2+ (peak = 340.68 mg/L), Na+ (peak = 360 mg/L), HCO3− (peak = 287 mg/L), Cl− (peak = 542 mg/L), SO42− (peak = 687 mg/L), NO3− (pek = 65.91 mg/L), fecal coliforms (FC) (peak = 160 UFC/mL), fecal Streptococcus (FS) (peak = 43 UFC/mL), and Clostridium perfringens (CP) (peak = 29 UFC/mL). Within the basin, two different facies have been identified: Cl-SO4-Na type and Cl-SO4-Ca type. The calculated Water Quality Index (WQI) indicates that none of the groundwater samples are suitable for drinking or human consumption. The detection of pathogenic microorganisms through diverse molecular methods has revealed the existence of eight distinct species, encompassing pathogenic strains that can affect human health. Moreover, the dissolution of geologic formations can influence the water's chemistry. In this region, groundwater pollution seems to be influenced by anthropogenic and agricultural factors such as fertilizer application, irrigation practices, and the release of domestic sewage. [ABSTRACT FROM AUTHOR]

Motivated by buoyancy-driven flows within geological formations, we study the evolution of a (dense) gravity current in a porous medium bisected by a thin interbed layer. The gravity current experiences distributed drainage along this low-permeability boundary. Our theoretical description of this flow takes into account dispersive mass exchange with the surrounding ambient fluid by considering the evolution of the bulk and dispersed phases of the gravity current. In turn, we model basal draining by considering two bookend limits, i.e. no mixing versus perfect mixing in the lower layer. Our formulations are assessed by comparing model predictions against the output of complementary numerical simulations run using COMSOL. Numerical output is essential both for determining the value of the entrainment coefficient used within our theory and for assessing the reasonableness of key modelling assumptions. Our results suggest that the degree of dispersion depends on the dip angle and the depth and permeability of the interbed layer. We further find that the nose position predictions made by our theoretical models are reasonably accurate up to the point where the no mixing model predicts a retraction of the gravity current front. Thereafter, the no mixing model significantly under-predicts, and the perfect mixing model moderately over-predicts, numerical data. Reasons for the failure of the no mixing model are provided, highlighting the importance of convective instabilities in the lower layer. A regime diagram is presented that defines the parametric region where our theoretical models do versus do not yield predictions in good agreement with numerical simulations. [ABSTRACT FROM AUTHOR]

Residual soils are found all around the world. Their behaviour is different from 'classic' soils due to the structure resulting from the geological formation processes, which can eventually undergo degradation under static and cyclic loads, with a decrease in both stiffness and strength. In this context, the aim of the present study was to evaluate the behaviour of weakly bonded residual soil in the face of loading and unloading cycles using field plate load tests. Preliminary field and laboratory tests were carried out to characterise the residual soil at the experimental site. Monotonic and cyclic plate load tests – with circular and square plates – were performed under three different load amplitudes. The results showed no shape effect of the loaded area for both monotonic and cyclic loading, considering the same loading pattern. Also, there is a threshold load, which indicates a yielding point and a change in soil behaviour and can be estimated from simple laboratory tests. Below this load, the residual soil presented a rigid behaviour even when subjected to cyclic loads. [ABSTRACT FROM AUTHOR]

The Guxiang–Tongmai segment of the Jiali fault is situated northeast of the Namche Barwa Syntaxis in northeastern Tibet. It is one of the most active strike‐slip faults near the syntaxis and plays a pivotal role in the examination of seismic activity within the eastern Himalayan Syntaxis. New study in the research region has yielded a 1:200000 gravity dataset covering an area 1500 km2. Using wavelet transform multiscale decomposition, scratch analysis techniques, and 3D gravity inversion methods, gravity anomalies, fault distributions, and density structures were determined across various scales. Through the integration of our new gravity data with other geophysical and geological information, our findings demonstrate substantial variations in the overall crustal density within the region, with the fault distribution closely linked to these density fluctuations. Disparities in stratigraphic density are important causes of variations in the capacity of geological formations to endure regional tectonic stress. Earthquakes are predominantly concentrated within the density transition zone and are primarily situated in regions of elevated density. The hanging wall stress within the Guxiang–Tongmai segment of the Jiali fault exhibits a notable concentration, marked by pronounced anisotropy, and is positioned within the density differential zone, which is prone to earthquakes. [ABSTRACT FROM AUTHOR]

This study evaluated the public health risks of radon (222Rn) in groundwater of Neyyar River Basin (NRB), southwest India. Among the 68 samples, 222Rn activity ranged from 0.25 to 61.7 Bq/L. Most geological formations, excluding charnockite, exhibited localized radon anomalies (> 11.1 Bq/L). Infants were the most radio-vulnerable age group and probabilistic health risk using Monte Carlo Simulation ranked infants (63.42%) > children (59.31%) > adults (58.57%) in the worst-case scenario. The integration of dose estimation, geospatial risk mapping, and Monte Carlo analysis presents an efficient approach for comprehensively evaluating the health risks associated with radon in groundwater. [ABSTRACT FROM AUTHOR]

Underground flow in fractured aquifers depends on the connectivity of the fractures, considered as a set of conduits and the main drainage axes. Quantitative analysis of fracture networks using multifractal characterisation therefore provides the backbone for assessing the connectivity of these networks. The aim of our work is to carry out a multifractal characterisation of lineament networks while performing related geometric, spectral and fractal analyses. The approach used is based on the box counting method to estimate the multifractal spectrum using the method of moments. The generalized fractal dimensions were estimated using the partition function and the multifractal spectrum using the Legendre transform. The work was carried out using a calculation code that we developed ourselves and that we named: 2D Calculation Code for Multifractal Analysis of Fracture Networks (2D-MAFN).Four lineament maps at different scales were analyzed, corresponding to the Upper Jurassic and Cretaceous geological formations of the El Gada region in the Central Algerian Saharan Atlas. The geometric analysis of the lineament networks showed good consistency between the lineament networks and the geological structure of the Atlas Range and its fault network. It also showed that the distribution of the lengths of the lineaments fits the power law. This analysis also revealed that, on a larger scale, diffuse fracturing appears to be more prevalent. In addition, the spectral analysis, through the decrease in spectral power according to a power law, characterizes a self-similar behavior and already seems to prove the scale invariance of the lineaments. The fractal dimension values obtained reflect the extent of fracturing and the degree of complexity of the network of lineaments. These values show that the lineaments are also well correlated with each other. The partition functions show that the points line up on the adjustment lines according to a law characteristic of multifractal behavior. In addition, the curves of generalized dimensions as a function of moments show a clear decrease, highlighting the multifractal nature of the fracturing process. In addition, the multifractal spectra in the form of bell curves also confirm the multifractal process for the four lineament networks analyzed. The results obtained are very encouraging and open up the prospects of modelling fracture networks for a variety of purposes, including assessing the connectivity of a fracture network. [ABSTRACT FROM AUTHOR]

Lake Salda is considered the most similar region on Earth to search for evidence of life on Mars, and its shoreline is home to microbialites containing some of the oldest known fossilized records of life on our planet. Understanding the historical process of Mars is also crucial for predicting the future of our planet, given its transition from a watery world to an arid one. In mineralogical studies to be carried out in sensitive areas such as private protected areas, it is a priority not to damage the area, and mineralogical research using remote sensing methods is frequently used in such studies. In this study, the mineralogical characteristics of the geological formations in and around Kocaadalar Burnu peninsula, located in the southwest of Lake Salda, were examined using remote sensing techniques. Mineral studies of Lake Salda were conducted using data from the Hyperion data of the Earth Observation-1 (EO-1) satellite, which can detect in 220 bands between 357 and 2576 nm wavelengths which is capable of hyperspectral sensing. The EO-1 satellite, the first spacecraft of NASA's New Millennium Programme, which operated successfully from its launch in 2000 until the end of its mission in 2017, carried the multispectral Advanced Land Imager and LEISA Atmospheric Corrector sensors, in addition to the Hyperion hyperspectral sensor. The Hyperspectral Material Identification tool in the Tactical Hyperspectral Operations Resource module of the ENVI software, the United States Geological Survey spectral library, and the Adaptive Coherence Estimator algorithm were used in the study. According to the results of this study conducted on the shores of Lake Salda, in addition to the hydromagnesite mineral, the existence of which was previously detected by various researchers, trona, vermiculite, rivadavite and borate minerals such as ulexite, tincalconite and colemanite were also detected. The results of this study have shown that remote sensing methods can make significant contributions to research in special protected areas such as Lake Salda. It is thought that the presence of trona and boron minerals in the region will contribute positively to the understanding of the historical process of Salda Lake. [ABSTRACT FROM AUTHOR]

High‐resolution 2D and 3D data remotely acquired by SuperCam's Remote Micro‐Imager and Mastcam‐Z aboard the Perseverance rover enabled us to characterize the stratigraphic architecture and sedimentary record of the Kodiak butte, an isolated remnant of the western delta fan of Jezero crater. Using these data, we build up on previous interpretations of the butte interpreted as a prograding Gilbert‐type deltaic series. We characterize three individual stratigraphic Units 0 to 2 on the eastern and northern faces of the butte. Each Unit displays the same vertical succession of prodeltaic/lacustrine bottomsets, delta slope toesets and foresets, and fluvially influenced topsets of a deltaic plain with a braided river pattern, shown by 11 individual sedimentary facies. We infer that these individual Units record the formation of three distinct deltaic mouth bars successively across time and space. For the first time on another planet than Earth, we are able to construct a precise sequence stratigraphic framework to highlight lake‐level fluctuations at the time the Kodiak butte was emplaced, during the latest stages of deltaic activity. We identify four hydrogeological cycles indicated by alternating rises and falls of the lake‐level on the order of 5–10 m. These were most probably linked to climatic events and variations controlling lake water inputs in probable relation to an astronomical control. Plain Language Summary: Kodiak butte is an isolated remnant of the main western sedimentary fan of Jezero crater. It displays the characteristic structures of a Gilbert‐type delta, a structure that shows deposition of fluvial material into a standing body of water, here interpreted to be a lake within Jezero crater. 11 individual sedimentary facies (textures, grain‐sizes, and structures) of the rocks exposed at Kodiak suggest that the depositional environments ranged from the fluvial plain to a steep subaqueous slope and into the bottom of the shallow Jezero lake. Our observations further show that Kodiak butte is organized into three distinct stratigraphic Units (0–2), each displaying the same vertical succession of bottomsets, toesets, foresets and topsets. This architecture is interpreted as reflecting three distinct deltaic packages, formed consecutively and not at the same time. Using these facies and stratigraphic architecture data, we are able for the first time on another planet than Earth, to precisely construct a sequence stratigraphic framework for the formation of Kodiak. This framework illustrates with unprecedented precision successive episodes of rises and falls of the paleo‐lake‐level (in the order of 5–10 m) involved in the construction and evolution of the western Jezero delta. Key Points: New observations on the Kodiak delta remnant were carried out to characterize its detailed facies and stratigraphic architectureThree deltaic mouth bars are identified showing 4D succession of depositional settings ranging from deltaic plain to slope to shallow lakeThe first ever sequence stratigraphic framework on Mars shows four cycles of alternating rises and falls of the lake‐level within 5–10 m [ABSTRACT FROM AUTHOR]

The article presents the results of studies of bottom landscapes carried out with the use of an echo sounder with a side-scan location function and supplemented by video filming from an underwater vehicle in a bay of one of the islands in the northern skerry area of Lake Ladoga in June 2022. The results of the echo sounding were used to develop a three-dimensional bathymetric model of the examined Haukaisenlahti Bay on Kukhka Island and to identify significant differences in comparison with published navigation maps for Haukaisenlahti Bay. The formation of the bed topography and the state of the shores in both above-water and underwater zones are determined by the specific features of the geological structure of this part of the water area, resulting from the different resistance to weathering processes in different geological formations. Six main types of facies were identified in the underwater landscape of the bay. The outlook and the change of facies are associated with the presence of hard rocky surfaces and hard clastic material followed by loose soils at greater depths. The outlook of the facies is also determined by the specific features of the bathymetric structure of the bay and the predominance of various associations of living organisms, the development of which depends on the type of surface and soil. The study confirmed the prospects of the use of echo sounders with a side-scan location function to study and map underwater landscapes of Lake Ladoga in combination with a remote video recording from an uninhabited vehicle. [ABSTRACT FROM AUTHOR]

Introduction: Carbon dioxide (CO2) enhanced gas recovery represents a viable strategy for sequestering CO2 while concurrently augmenting gas production from subsurface reservoirs. Gas reservoirs, as inherent geological formations, are optimal repositories for gaseous compounds, rendering them suitable for CO2 storage. Nevertheless, the economic viability of pure CO2 storage necessitates integration with oil and gas recovery mechanisms to facilitate widespread CO2 utilization. Method: This study addresses the complexities of CO2 enhanced gas recovery through a comprehensive approach that combines theoretical model and numerical simulations. A numerical model is developed to simulate three-component diffusion involving CO2, and methane (CH4) in a two-phase system comprising gas and water. Results: The investigation systematically explores the process of enhanced CH4 extraction and CO2 injection into the reservoir and examines the influencing factors on extraction. Simulation results reveal a power-law decrease in CH4 production rate, stabilizing at a constant extraction rate. Enhanced CH4 extraction benefits from increased porosity, with higher porosity levels leading to greater CH4 extraction. Permeability augmentation positively influences CH4 production, although with diminishing returns beyond a certain threshold. The CO2 injection rate shows a direct proportionality to CH4 production. However, elevated CO2 injection rates may increase reservoir pressure, potentially causing cap rock damage and CO2 gas flushing. Discussion: This study contributes valuable theoretical insights to the field of CO2 enhanced gas recovery engineering, shedding light on the intricate dynamics of multi-component fluid transport processes and their implications for sustainable CO2 utilization. [ABSTRACT FROM AUTHOR]

Investigating the mineralogical compositions of soils under different geological formations becomes imperative for maximizing agricultural productivity and ensuring the long-term viability of agricultural practices. Therefore, studies were carried out on mineral compositions and diversities of soils developed over the Basement complex rock, Coastal plain sands and Ewekoro formations in Ogun state Nigeria. A total of nine profile pits (three per location) of 2 m × 1 m × 2 m size were dug in all the three locations. Soil samples were collected from the pedogenic horizons of each profile pits in replicates into a well labeled polyethylene bag. Using X-ray diffractometry (XRD) and scanning electron microscopy (SEM) the mineral contents and their relative abundance, elemental compositions and morphologies of the fine sand, coarse silt and clay fractions of the soils at different topographic positions were identified, described and compared. Results obtained from XRD and SEM analyses exhibited similarities. The most abundant elements in the basement complex and Ewekoro pedon were oxygen, carbon and silicon whereas in the coastal plain sand pedon, oxygen, carbon and aluminum were the most abundant element. The presence of mixed-layer illite, mica, kaolinite, quartz, hematite, anatase, goethite, and chlorite at varying degrees was observed in the pedons developed on these geological formations, although kaolinite and quartz dominated the soil matrix. The mineralogical complexity of the pedons followed the order of basement complex > coastal plain sand > Ewekoro formation. Profiles developed on the Ewekoro formation exhibited the highest degree of weathering, as evidenced by their chemical properties and mineralogical compositions. The petrographic evaluation of the three geological formations revealed that all pedons were rich in quartz and exhibited varying degrees of mineral complexity and maturation. The overlapping and distinct characteristics among the geologies indicated different stages of weathering. By using the mineral maturity index, profiles developed over the basement complex rock and the coastal plain sand could be regarded as sub-matured and this could have contributed significantly to the native fertility of these soils and profiles from the Ewekoro formation were the most weathered. The use of Ewekoro formation for agriculture would necessitate significant investments in agro-inputs and sound principles of soil management through integrated soil fertility management. [ABSTRACT FROM AUTHOR]

This technical note describes the FluidFlower concept, a new laboratory infrastructure for geological carbon storage research. The highly controlled and adjustable system produces a strikingly visual physical ground truth of studied processes for model validation, comparison and forecasting, including detailed physical studies of the behavior and storage mechanisms of carbon dioxide and its derivative forms in relevant geological settings for subsurface carbon storage. The design, instrumentation, structural aspects and methodology are described. Furthermore, we share engineering insights into construction, operation, fluid considerations and fluid resetting in the porous media. The new infrastructure enables researchers to study variability between repeated CO2 injections, making the FluidFlower concept a suitable tool for sensitivity studies on a range of determining carbon storage parameters in varying geological formations. [ABSTRACT FROM AUTHOR]

Carbon capture and storage is one of the key technologies that can help industries limit their environmental footprint and societies achieve the climate change mitigation goals. The process entails capturing CO 2 and injecting it into deep geological formations for permanent storage. However, the design and modeling of carbon sequestration projects entail significant challenges in assessing the risks and long-term consequences. The fate of CO 2 in the subsurface is dictated by many processes including solute transport, multiphase compositional effects, and trapping mechanisms. The ability to properly capture these phenomena is limited by the abstraction of numerical models, the uncertainty in petrophysical characterization, and the modeling of the thermodynamic effects. In this work, we study the impact of each of these factors on the fate of CO 2 injection in a meter-scale experimental setup. We model the evolution of the CO 2 plume inside the tank using the compositional reservoir simulator IPARS (Integrated Parallel Accurate Reservoir Simulator). We then present an ensemble-based approach to quantify the uncertainties and study the predictability of the numerical models. The results emphasize the ability of the reservoir simulator to predict the evolution of CO 2 in the FluidFlower experimental setup. They also highlight the importance of considering the uncertainty in experimental testing of petrophysical properties in the risk assessment of geological carbon storage projects. [ABSTRACT FROM AUTHOR]

Successful deployment of geological carbon storage (GCS) requires an extensive use of reservoir simulators for screening, ranking and optimization of storage sites. However, the time scales of GCS are such that no sufficient long-term data is available yet to validate the simulators against. As a consequence, there is currently no solid basis for assessing the quality with which the dynamics of large-scale GCS operations can be forecasted. To meet this knowledge gap, we have conducted a major GCS validation benchmark study. To achieve reasonable time scales, a laboratory-size geological storage formation was constructed (the "FluidFlower"), forming the basis for both the experimental and computational work. A validation experiment consisting of repeated GCS operations was conducted in the FluidFlower, providing what we define as the true physical dynamics for this system. Nine different research groups from around the world provided forecasts, both individually and collaboratively, based on a detailed physical and petrophysical characterization of the FluidFlower sands. The major contribution of this paper is a report and discussion of the results of the validation benchmark study, complemented by a description of the benchmarking process and the participating computational models. The forecasts from the participating groups are compared to each other and to the experimental data by means of various indicative qualitative and quantitative measures. By this, we provide a detailed assessment of the capabilities of reservoir simulators and their users to capture both the injection and post-injection dynamics of the GCS operations. [ABSTRACT FROM AUTHOR]

Geoscientists now identify coal layers using conventional well logs. Coal layer identification is the main technical difficulty in coalbed methane exploration and development. This research uses advanced quantile–quantile plot, self-organizing maps (SOM), k-means clustering, t-distributed stochastic neighbor embedding (t-SNE) and qualitative log curve assessment through three wells (X4, X5, X6) in complex geological formation to distinguish coal from tight sand and shale. Also, we identify the reservoir rock typing (RRT), gas-bearing and non-gas bearing potential zones. Results showed gamma-ray and resistivity logs are not reliable tools for coal identification. Further, coal layers highlighted high acoustic (AC) and neutron porosity (CNL), low density (DEN), low photoelectric, and low porosity values as compared to tight sand and shale. While, tight sand highlighted 5–10% porosity values. The SOM and clustering assessment provided the evidence of good-quality RRT for tight sand facies, whereas other clusters related to shale and coal showed poor-quality RRT. A t-SNE algorithm accurately distinguished coal and was used to make CNL and DEN plot that showed the presence of low-rank bituminous coal rank in study area. The presented strategy through conventional logs shall provide help to comprehend coal-tight sand lithofacies units for future mining. [ABSTRACT FROM AUTHOR]

The innovative cutting mechanism of multi-dimensional teeth presents a groundbreaking approach to drill bit design, particularly optimizing drilling efficiency in challenging geological formations such as interlayers and gravel-rich layers within the Changqing Oilfield. Nevertheless, compared to conventional flat-tooth PDC drill bits, several aspects of the cutting mechanism and design parameters for multi-dimensional teeth require further elucidation. This article employs a linear cutting finite element model to establish cutting models for traditional flat teeth and two distinct types of multi-dimensional teeth, designated as Ridge and Benz. It systematically investigates the influence of varying cutting parameters on the effectiveness of rock-crushing within the multi-dimensional tooth-cutting mechanism. This study conducts laboratory-based single-tooth rock-crushing experiments to validate the numerical simulation results. Furthermore, applying principles derived from soil plastic mechanics contrasts the stress states experienced by rocks during the rock-crushing process between multi-dimensional teeth and conventional flat teeth, shedding light on the rock-crushing mechanism employed by multi-dimensional teeth. This research categorizes PDC cutting teeth on the drill bit into two groups: those near the center and those near the outer shoulder. A linear cutting model for teeth positioned near the outer shoulder is developed to analyze the impacts of different rake angles, side clearance angles, and welding errors on the tooth helix angle and the rock-crushing efficiency of the Benz tooth. This comprehensive study is a valuable reference for tailored drill bit design and holds potential for publication in a prestigious scientific journal. [ABSTRACT FROM AUTHOR]

In this study, the geological and petrophysical methods were combined to investigate the reservoir characteristics of the Asmari Formation in one of the gas fields in the Persian Gulf. The key focus of this study is to categorize rock types and define reservoir zonation. Initially, sedimentary facies were identified through the analysis of the core samples and the petrographic studies. Subsequently, the depositional environments of each facies were interpreted. After assessing the reservoir quality of sedimentary facies, various rock typing methods, including FZI, R35, and Lucia methods, were used to categorize the reservoir rocks. Finally, reservoir zonation was carried out based on the integration of information and the NCRQI method. According to this study, the Asmari Formation in the studied field consists of 10 sedimentary facies deposited in a carbonate ramp environment during the Rupelian and Chattian stages. From the perspective of frequency, coralgal reef facies play a significant role in this platform, while from a reservoir standpoint, the thin-bedded ooid grainstones are the most important reservoir facies. The high variability in porosity and permeability data for each facies indicates the importance of diagenetic changes in reservoir quality and porosity distribution. A comparative analysis of rock typing methods revealed that the reservoir rock is composed of five reservoir rock types, associated with different sedimentary facies, pore sizes, and reservoir properties. Finally, based on the integration of geological and petrophysical information, the reservoir rock was divided into five reservoir zones, with reservoir zones As-2 and As-4 being the most important due to their relatively high porosity and permeability. [ABSTRACT FROM AUTHOR]

Carbon dioxide is a suffocating gas resulting either from industrial activities from combustion or explosion. There may also be carbon dioxide deposits under pressure, quartered in porous geological formations. This gas can show slow or violent releases with accumulation at ground level. Carbon dioxide is a gas that is both toxic and asphyxiating. This gas can accumulate in closed spaces and when it exceeds the concentration of 12% vol. it becomes lethal. For the protection of working personnel, it is necessary to identify and apply the most effective preventive measures. This requires an understanding of carbon dioxide's behaviour during the build-up phase. The research gives a CFD analysis for determining the dynamics of carbon dioxide dispersion in a confined enclosure. [ABSTRACT FROM AUTHOR]

Thermal pressurization of the trapped pore fluid is considered to be a widespread fault weakening during fluid injection in confined geological formations. Tremendous amounts of heats will be generated within the narrow shear zone during fault slip. Considering the melting of the fault gouge, the fault seal zone is adopted to construct the fluid pressurization model, thermal pressurization implemented in Comsol Multiphysics is established to illustrate the fault weaken coefficient and effective normal stress during fluid injection. The friction weakening coefficients mT and mF are proposed to research the performance of fault weakening during fluid injection. The results indicate that, the friction coefficients mT and mF both exhibit the initially decreasing and then increasing tendency, and thermal-induced fault weakening of CO2 injection occurs earlier than that of water injection. It was found that initial pore pressure and fault sealing porosity have a negligible influence on the evolutions of friction weakening and effective normal stress. Initial normal stress and fault sealing permeability have certain obvious influences on fault weakening during CO2 injection. Fault thickness is the primary factor influencing the friction weakening coefficient. When the fault thickness is over 1 mm, the variation of fault weakening is totally different from that when the thickness is less than 1 mm. This investigation of friction weakening during fault slip provides an effective reference for fluid injection. [ABSTRACT FROM AUTHOR]

Spectral transform, known as a curvelet, enables sparse representations of complex data. Denoising wave propagation in disordered media and pattern recognition are just a few of the numerous domains in which denoising has a potential application. Based on directional basis functions, this spectral method represents objects with discontinuities along a smooth curve. In this study, we used this technique to eliminate ground roll, an unwanted feature signal that can be seen in seismic data obtained by sonating the earth's geological formations. Additionally, we improved the curvelet transform threshold denoising method combined with a fast non-local mean to remove seismic random noise. First, cyclic translation and block complex domain threshold methods were introduced into the curvelet transform threshold denoising, and the traditional curvelet threshold denoising method was improved to obtain the best denoising results; Subsequently, the removed noise was filtered using a fast non-local mean method to obtain a valid signal. Finally, the data obtained in the above two steps were added to obtain the final denoising result. The results of the model tests and actual seismic data denoising showed that the denoising results obtained using this method had a higher signal-to-noise ratio and fidelity than that using the other methods. [ABSTRACT FROM AUTHOR]

Much of the continental margins in the world oceans provide the necessary thermodynamic conditions to store CO 2 as ice-like hydrates (CO 2 · 6 H 2 O). While resistant to buoyant migration and leakage, the fundamental growth mechanisms that control the injection, capacity, and security of CO 2 hydrates stored in the seafloor remain unresolved. Extensive field and laboratory testing give rise to conflicting views on the kinetics and growth configurations of hydrates, where mechanistic models reconciling the formation of hydrates observed in nature remain missing. This work elucidates a fundamental pore-scale reactive transport mechanism that underpins the rate and morphology of hydrate formation. We reveal a previously unrecognized mode of hydrate formation in porous seafloor sediments, hydrate film growth via reaction-imbibition, where superhydrophilic hydrate crystallites ( θ ∼ 0 ∘ ) formed at water–CO 2 interfaces create a secondary microporous medium (∼ 10 to 100 nm pores) within lithologic sediment pores (∼ 10 to 100 μ m pores) to promote further hydrate growth. Unlike past diffusion-controlled models, we show that spontaneous water imbibition into the hydrate micropores establishes rapidly new water–CO 2 interfaces (i.e., hydrate formation surfaces) via capillary-driven convection and is the dominant mechanism for supplying water to the hydrate formation interface. [ABSTRACT FROM AUTHOR]

Progressive climate change may have unpredictable consequences for the Arctic environment. Permafrost catchments off the west coast of Svalbard, described as "thin" and "warm," are particularly sensitive to climate change. The interdisciplinary research on the hydrochemical response of surface and underground water functioning within a small permafrost catchment area focused on the determination of the impact of meteorological conditions (temperature (T), precipitation (P)) on the mean daily discharge (Q), and the lowering of the groundwater table (H). We determined physical and chemical properties (pH and SEC) and concentrations of major elements (Ca, Mg, Na, K) and 23 trace elements (i.a. Cd, Cu, Hg, Pb, Zn) in 280 water samples. The results of the correlation matrix showed that an increase in the average air temperature in the summer of 2021 had a significant impact on the hydrochemistry of both types of waters operating in the catchment. In response to increase in T, the lowering of the H (0.52 < r < 0.66) and a decrease in Q (−0.66 < r < −0.68) were observed what in consequence also leads to changes in water chemistry. The principal component analysis (CA) indicates that chemical weathering and binding of elements to DOC are processes influencing water chemistry. Results of statistical analysis showed that the resultant of the hydrometeorological conditions that prevailed in that season and the type of geological formations on which they were located had a significant impact on the water chemistry at individual measurement points. Significant differences in the concentrations of elements between points on the same geological formations were also found. [ABSTRACT FROM AUTHOR]

In gripper tunnel boring machine (TBM) tunneling through complex geological formations, the safe and efficient recovery from large-scale collapses remains a formidable challenge. In this study, we investigate the causes of a 1246 m3 collapse that occurred during the gripper TBM tunneling in the diversion tunnel in Xinjiang, China. Various techniques including TSP seismic waves, CFC advanced water exploration, laboratory point load tests and packer permeability tests were employed for thorough research. The examination discloses that the water softening in biotite-quartz schist in fractured zones contributes significantly to the loosening and dislocation of rock layers along joints. The gripper TBM's cutterhead exacerbates this process through cutting action and vibrations, causing large-scale instability and eventual rock mass collapse. To tackle this engineering problem, we propose a three-step treatment scheme comprising "Reinforcement-Backfill-Re-excavation". Furthermore, we propose a technique to handle TBM collapses by creating a "protective shell" within the cavity. The safety and feasibility of these proposed solutions were thoroughly validated through numerical simulations. Also, we utilized the Hoek-Brown theory and Rostami prediction formula to establish recommended values for the total thrust and total torque of the TBM during the collapsed section. The proposed treatment scheme and estimated parameters were successfully applied, resulting in a comprehensive solution from collapse handling to tunneling. This study offers valuable details on effectively managing large-scale collapses in gripper TBM tunneling, which can be useful for similar tunnel engineering and improve safety and efficiency. [ABSTRACT FROM AUTHOR]

The increasing use of finite element analysis in modern infrastructure design emphasizes the importance of determining soil stiffness at small strains. This is usually represented by the normalized shear modulus degradation curve, which is crucial for accurate design. In the absence of specific measurements on the local soil, engineers often rely on empirical correlations and assume comparable behavior of soils with similar intrinsic properties. However, the application of this approach leads to uncertainties, especially for unique geological formations such as the soft cohesive soils of the Ljubljana Marsh. The main objective of this study was to determine the small strain shear modulus of Ljubljana Marsh soil with a plasticity index between 11 and 35%. Isotropic and anisotropic stress conditions were investigated as part of an extensive laboratory test program that included 45 bender element and 89 resonant column tests on 20 soil samples. By emphasizing the importance of measuring soil stiffness at small strains, this study not only provides reliable data for the development of the built environment in the Ljubljana Marsh and similar areas, but also underlines its necessity. [ABSTRACT FROM AUTHOR]

The objective of this paper is to determine whether the flood-spreading system at the Tasuj station in east Azerbaijan, Iran, has caused inappropriate chemical alterations to the properties of the soil. One question is whether the flood-spreading system was constructed at an inappropriate location leading to unintentional consequences. Composite soil samples were taken from three flooded areas, from three grids in each flooding area, and from two depths. Chemical characteristics of the soil including electrical conductivity, pH, concentrations of bicarbonate, chloride, sodium, calcium, and magnesium ions, and the sodium adsorption ratio in the flooded areas were measured. Because of calcareous, gypsum, shale, and marl formations in the first flooded area, dissolution of solutes of these formations increased the concentration of ions in the runoff (especially sodium and chlorine, to 19.50 and 21.90 mmol (charge) L−1, respectively). These high ion concentrations caused the electrical conductivity of the runoff to increase significantly (up to 2.03 dS/m) compared to the other areas. High amounts of lime in the soil caused increasing buffering capacity of the area soil, as a consequence the flood-spreading did not cause significant changes to the soil pH and showed a difference of only 0.3–0.2 in the first flooded area compared to other areas. HIGHLIGHTS Soil samples were extracted from grids in multiple flood areas and from multiple depths.; Chemical characteristics in the flooded areas were measured.; It is concluded that the flood-spreading system was constructed in an appropriate location.; There is a minor problem associated with salts in the initial parts of flooded area.;

Assessing microbial risks is key to feasible hydrogen storage in geological formations. This work quantitatively analyses the impacts of bio-methanation on hydrogen storage performance. Fine-scale flow simulations, coupled with the bio-methanation reaction, are presented to analyse its impact on the storage performance. Based on the reported rates in literature, methanogenesis may slightly degrade the recovery performance of hydrogen but is considered minor compared with the issue of gas mixing. The impacts of methanogenesis on a time scale of months (330 days) becomes observable in the system configured here, when the methanation rate is above 1746 nano molality per hour. The assumed methanation rate is two times greater than the rate reported from the Olla filed. Validated scaling theory generalises findings for gravity-dominated scenarios. But viscous-dominated flows see complications from property variations due to pressure changes at high rates. This study provides definitions of "target properties" (e.g., acceptable methanogenesis rates) for screening hydrogen storage projects. • A new synthesis incorporating methanogenesis and flow dynamics is developed. • Effects of methanogenesis should be considered if the reaction rate is greater than 1746 nm h−1. • Fluid mixing driven by viscous fingering may amplify the process of methanogenesis. • The methanation process may lead to or accelerate the water breakthrough. • Scaling theory is validated for a gravity-dominated scenario with methanogenesis considered. [ABSTRACT FROM AUTHOR]

Deep crustal production of hydrogen (H2) is a potential source of primary energy if recoverable accumulations in geological formations are sufficiently large. We report direct measurements of an elevated outgassing rate of 84% (by volume) of H2 from the deep underground Bulqizë chromite mine in Albania. A minimum of 200 tons of H2 is vented annually from the mine’s galleries, making it one of the largest recorded H2 flow rates to date. We cannot attribute the flux solely to the release of paleo-fluids trapped within the rocks or to present-day active and pervasive serpentinization of ultramafic rocks; rather, our results demonstrate the presence of a faulted reservoir deeply rooted in the Jurassic ophiolite massif. This discovery suggests that certain ophiolites may host economically useful accumulations of H2 gas. [ABSTRACT FROM AUTHOR]

The data of gas-geochemical studies of bottom sediments of the Laptev—Siberian Sea transition zone are presented. The established isotope–geochemical parameters indicate the domination of epigenetic hydrocarbon gases of various gas sources in the sediments. Methane concentrations up to 8.3047 cm3/kg and the sum of homologues up to 0.0260 cm3/kg indicate the formation of hydrocarbon anomalies exceeding the anomaly criteria for Arctic shelf sediments by a factor of 166 and 26. The main geological factors for the formation and distribution of anomalies in the bottom sediments of the Laptev–Siberian Sea transition zone are the high gas content of the underlying sediments and gas sources, the fold and fault tectonics, the geostructural position, the seismic activity, and the depth of occurrence of hydrocarbon gas sources. [ABSTRACT FROM AUTHOR]

Determining the elastic modulus of rocks is one of the crucial parameters in civil and petroleum engineering. Asmari geological formation is widely outcropped in a significant part of the west and SW of Iran and NE of Iraq. Understanding the static elastic modulus of host rocks is crucial because of the design and construction of numerous geotechnical structures and the presence of large hydrocarbon reservoirs in this formation. To determine the elastic modulus of intact rocks, the uniaxial compressive strength test is typically used. However, in jointed rocks and deep areas, where obtaining samples may be challenging, costly, or even impossible, correlations between static–dynamic elastic modulus (Es − Ed) is more frequently employed. Although some scholars have proposed correlations between Es − Ed, they had determined dynamic modules based on the ultrasonic test. In the aforementioned test, intact samples are used and the effect of discontinuities would not be considered; hence, the results cannot be considered as rock mass representative. In this study, to consider field geotechnical conditions, the dynamic modules were determined based on the downhole seismic test (DS) in a tunnel in located the west of Iran. Then from the results of static elastic modulus, which were obtained from core samples, a linear correlation was proposed between Es − Ed. The root-mean-square error and variance accounted showed that the predicted static elastic modulus by the proposed correlation is more accurate to a large extent. In addition, unlike the ultrasonic-based Ed, the results showed that the DS-based Ed is less than Es. [ABSTRACT FROM AUTHOR]

Geologic carbon sequestration requires CO2 injection into the storage formation at high‐injecting pressure. Such high pressure could induce choked flow accompanying huge variations in thermodynamic properties of CO2 at a converging‐diverging (CD) fractures in the storage formation. In this study, high‐velocity CO2 transport through CD fractures was investigated to quantify the effect of fracture morphology on occurrence of both choked flow and shockwave that constrain the mass flow rate of fluid. In addition, variations in thermodynamic CO2 properties including Mach Number (Ma), defined by the ratio of fluid velocity to sound speed, and shock properties were investigated. The morphological characteristics of CD fractures were determined by nine properties, such as throat diameter, throat length, inlet diameter, outlet diameter, throat diameters of two‐connected CD fractures, fracture wall curvature, roughness amplitude, and frequency. As a result, the throat diameter crucially affected choked flow occurrence and maximum Ma. When the inlet and outlet diameters varied, the profiles for Ma variation were consistent in the converging and diverging segments, respectively. In addition, regardless of change in the throat length, the position of maximum Ma was nearly constant with showing the position length ratio of 0.13–0.14. However, roughness of fracture wall significantly influenced the Ma variation and occurrence of shock. In particular, backflows segregated from the main CO2 flow were observed near the wall roughness. Plain Language Summary: Choked flow is a fluid‐mechanical process that restricts the mass flow rate of fluid and it can be occurred when fluid velocity overcomes its sound speed. When CO2 is injected into the targeted geologic formation, choked flow can occur due to highly pressurized flow within the fractures located near the CO2 injection well. Once choked flow occurred, the shock, which accompanies substantial changes in the thermodynamic properties of CO2, follows in the fractures. In the study, choked flow is generated within the converging‐diverging (CD) fracture which serves as a pathway of injected CO2, and its cross‐sectional area decreases and increases again after the "throat." We assumed that the CD fractures have various morphologic properties and analyzed the relationship between the fracture morphology and shock properties. The results highlighted that the throat diameter and fracture roughness mainly affected choked flow occurrence and shock properties. Findings here are applicable to other site‐specific studies, such as volcanoes, geysers, geothermal fields, and underground hydrogen storage sites where highly compressed fluid often migrates through subsurface fractures or any types of geologic conduits. Key Points: CO2 flow within the fracture was simulated to evaluate the effect of fracture morphology on choked flow and shock generationMorphologic properties including throat diameter and length, inlet and outlet diameter, number of throats, and wall roughness were variedThroat diameter influenced the Mach number (Ma); a complicated trend of Ma and backflow were observed owing to wall roughness [ABSTRACT FROM AUTHOR]

Anomalous solute migrations in fractured rocks are governed by geometric characteristics and flow regimes. Although existing inverse models can describe this behavior, the underlying physics for quantifying key transport coefficients remains largely unexplored. Here, we investigate the quantitative impacts of geometric heterogeneity and flow regimes on solute transport in rock fractures. We conduct numerical experiments to simulate water flow and conservative solute transport in 3D fractures with varying geometric features and Reynolds numbers. Our results show that the non‐Fickian transport is prevalent across the entire flow regime, with Darcy flows attributed to geometric heterogeneity and non‐Darcian flows influenced by additional eddy zones. We employ the mobile‐immobile (MIM) domain model and continuous time random walk (CTRW) model to inversely model simulated breakthrough curves. Inverse analyses demonstrate that both models effectively characterize anomalous transport behaviors. The fitted transport coefficients of the MIM model exhibit stronger quantitative relationships with aperture and roughness parameters, as well as Reynolds number, compared to the CTRW model. By incorporating parameterized transport coefficients, we propose physics‐ and statistics‐based models to directly predict anomalous transport behaviors under different flow regimes. These prediction models accurately reproduce solute transport processes of all simulated cases with acceptable errors. The feasibility of directly predicting solute transport under varying flow regimes using geometric information is thus validated. Our study not only supports the study of substance migration based on geometric structure features, but also serves as a foundation for investigating geological activities based on substance migration information. Plain Language Summary: The migration of substances within geological formations is governed by their geometric pore structure, while information about substance migration can reveal the geometric characteristics of these formations. In this context, these two aspects form an interdependent feedback system. Investigating quantitative relationships and models between the geometry of geological formations and substance migration is thus crucial for understanding various geological processes related to geometric structure changes and hydrogeochemical signals (i.e., chemical information carried by groundwater or surface water, which reflects various natural and anthropogenic geological processes) evolution. Here, we explore the impact of both geometric structure and hydrodynamic conditions on solute transport in rock fractures. We conduct extensive direct numerical simulations to determine the inherent quantitative relationships between key transport coefficients and geometric parameters under different flow regimes. Based on these relationships, we establish upscaling models for directly predicting solute transport processes using only geometric parameters within both physics‐ and statistics‐based frameworks. This research has significant implications for predicting solute migrations using measurable physical properties and offers potential applications for studying geological activities related to fractured rocks through analyzing released hydrogeochemical signals. Key Points: Non‐Fickian transport behaviors in 3D fractures under different Re were characterized within physics‐ and statistic‐based frameworksTransport coefficients within mobile‐immobile and continuous time random walk frameworks were systematically parameterized by geometric and hydrodynamic parametersDirectly predicting solute transport via geometric parameters under different Re is feasible in both physics‐ and statistic‐based frameworks [ABSTRACT FROM AUTHOR]

Tabular Middle Atlas of Morocco holds the main water reservoir that serves many cities across Morocco. Dolomite and limestone are the most dominant geologic formations in this region in which water resources are contained. The recent studies conducted to evaluate the quality of this water suggest that it is very vulnerable to pollutants resulting from both anthropogenic and natural phenomenon. High and very high-resolution satellite imagery have been used in an attempt to gain a better understanding of this karstic system and suggest a strategy for its protection in order to reduce the impact of these phenomenon. Based on the surface reflectance of land cover benchmarks, the karstic system has been horizontally delineated, as well as regions with intense human activities. Using band combination in the portion of the infrared, shortwave infrared, and visible parts of the electromagnetic spectrum, we identified bare lands which have been interpreted as carbonate rocks, clay minerals, uncultivated fields, basalts rocks, and built-up areas. Other classes such as water and vegetation have been identified. Carbonate rocks have been identified as areas with a high rate of water infiltration through their fracture system. Using a Sobel operator filter, these fractures have been mapped and their results have revealed new and existing faults in two major fracture directions, NE-SW and NW-SE, where NE-SW is the preferable pathway for surface water infiltration towards the groundwater reservoir, while the NW-SE direction drains groundwater from the Cause to the basin of Saiss. Over time, the infiltration of surface water through fractures has contributed to a gradual erosion of the carbonate rocks, which in turn developed karst landforms. This karst system is vulnerable due to the flow of pollutants in areas with shallow sinkholes. Using GDEM imagery, we extracted karst depressions, and their analysis shows that they are distributed along the fracture system and many of them were located on curvilinear or linear axes along the NE-SW fracture direction. We found also dolines scattered in areas with a high intensity of fractures. This distribution has been validated by both on-the-ground measurements and very high-resolution satellite images, and depressions of different forms and shapes dominated by dolines, poljes, lapiez, and avens have been identified. We also found many water springs with a highly important water output, such as the Ain Maarrouf water spring. The aim of this study is to enhance the understanding of the hydrogeological system of TMA, to improve the existence of the fracture database in the Cause of Agourai, and to establish a new morpho-structural picture of the Ain Maarrouf water spring. [ABSTRACT FROM AUTHOR]

Accurate identification and understanding of various metallic minerals are crucial for deciphering geological formations, structures, and ages. Giving their pivotal role as essential natural resources, a microscopic exploration of metallic minerals becomes imperative. Traditional analytical methods, while helpful, exhibit certain limitations. However, terahertz time-domain spectroscopy, distinguished by its high signal-to-noise ratio, expansive frequency band, and low incident wave energy, is a promising complement to conventional techniques in characterizing metallic minerals. This study employs terahertz time-domain spectroscopy to examine samples of Stibnite, Sphalerite, Galena, and Pyrite originating from diverse geological conditions. The vibrations of molecules within these metallic minerals induce discernible changes in the terahertz spectra. Our findings untiate the extensive potential of terahertz time-domain spectroscopy in the characterization of metallic minerals, affirming its considerable practical value in mineral resource exploration. [ABSTRACT FROM AUTHOR]

The Taoudeni basin occupies a large portion of the West African Craton in Mauritania, Mali, SW Burkina Faso, and Algeria. The multi-layer Taoudeni aquifer system (TAS) occurs in geological formations extending in age from the Infra-Cambrian to the Quaternary. These groundwater resources support local livelihoods, maintain vital ecosystems, and strongly affect terrestrial water and energy budgets in the region. Hydrogeochemical and stable (δ2H, δ13C, δ18O) and radioactive (3H, 14C) isotope analyses were carried out with the aim of identifying the major geochemical processes controlling groundwater quality and the recharge mechanisms. The analyzed groundwater samples showed a wide range of chemical compositions based on major ions, with limited variability, regardless of the aquifer lithology or stratigraphy. The predominant water type, Mg–Ca–HCO3, was found in most geological and hydrogeological settings. A principal component analysis of the hydrochemical data revealed the two major processes governing the geochemistry of groundwaters in the TAS. These are water–rock interaction (leaching, weathering, ion exchange) and anthropogenic contamination. Environmental isotopes revealed the presence of groundwaters with heterogeneous signatures, reflecting different recharge processes and varying groundwater ages. A widespread present-day recharge by direct infiltration of rainwater and/or by surface water was highlighted by significant tritium levels in most wells and high 14C activities occurring mainly in shallow aquifers. However, isotopically depleted δ18O contents with low 14C activities were found in the confined part of the Continental Intercalaire aquifer, particularly in the Algerian part, indicating the presence of fossil groundwater, recharged under colder past climatic conditions. [ABSTRACT FROM AUTHOR]

Background: Arsenic is a naturally occurring element that poses a significant threat to human health due to its widespread presence in the environment, affecting millions worldwide. Sources of arsenic exposure are diverse, stemming from mining activities, manufacturing processes, and natural geological formations. Arsenic manifests in both organic and inorganic forms, with trivalent meta-arsenite (As3+) and pentavalent arsenate (As5+) being the most common inorganic forms. The trivalent state, in particular, holds toxicological significance due to its potent interactions with sulfur-containing proteins. Objective: The primary objective of this review is to consolidate current knowledge on arsenic toxicity, addressing its sources, chemical forms, and the diverse pathways through which it affects human health. It also focuses on the impact of arsenic toxicity on various organs and systems, as well as potential molecular and cellular mechanisms involved in arsenic-induced pathogenesis. Methods: A systematic literature review was conducted, encompassing studies from diverse fields such as environmental science, toxicology, and epidemiology. Key databases like PubMed, Scopus, Google Scholar, and Science Direct were searched using predetermined criteria to select relevant articles, with a focus on recent research and comprehensive reviews to unravel the toxicological manifestations of arsenic, employing various animal models to discern the underlying mechanisms of arsenic toxicity. Results: The review outlines the multifaceted aspects of arsenic toxicity, including its association with chronic diseases such as cancer, cardiovascular disorders, and neurotoxicity. The emphasis is placed on elucidating the role of oxidative stress, genotoxicity, and epigenetic modifications in arsenic-induced cellular damage. Additionally, the impact of arsenic on vulnerable populations and potential interventions are discussed. Conclusions: Arsenic toxicity represents a complex and pervasive public health issue with far-reaching implications. Understanding the diverse pathways through which arsenic exerts its toxic effects is crucial to developing effective mitigation strategies and interventions. Further research is needed to fill gaps in our understanding of arsenic toxicity and to inform public health policies aimed at minimising exposure. Arsenic toxicity is a crucial public health problem influencing millions of people around the world. The possible sources of arsenic toxicity includes mining, manufacturing processes and natural geological sources. Arsenic exists in organic as well as in inorganic forms. Trivalent meta-arsenite (As3+) and pentavalent arsenate (As5+) are two most common inorganic forms of arsenic. Trivalent oxidation state is toxicologically more potent due to its potential to interact with sulfur containing proteins. Humans are exposed to arsenic in many ways such as environment and consumption of arsenic containing foods. Drinking of arsenic-contaminated groundwater is an unavoidable source of poisoning, especially in India, Bangladesh, China, and some Central and South American countries. Plenty of research has been carried out on toxicological manifestation of arsenic in different animal models to identify the actual mechanism of aresenic toxicity. Therefore, we have made an effort to summarize the toxicology of arsenic, its pathophysiological impacts on various organs and its molecular mechanism of action. [ABSTRACT FROM AUTHOR]

The co-ordinates of the area studied are within latitudes 5°29' to 5°51 'N and longitudes 7°29' to 8°00' E. The Nsukka Formation in the studied area consists of two facies associations; limestone-shale and cross bedded sandstone. The Limestone-shale facies association consists of the following lithofacies; rippled clayey sandstone, carbonaceous shale, heterolithic sandstone-shale, laminated grey shale, fossiliferous limestone, Fine grained sandstone, Silty shale, Medium grained sandstone and carbonaceous sandstone. The cross bedded sandstone facies association consists of only cross bedded sandstone. Representative samples of these rocks from Ohafia area were collected and stored in a polythene bag for further investigations. XRF analyses were carried out on these rock samples. The XRF oxide content of elements in sample OHA 1 of original rock was found to be CaO (76.00), Fe2O3 (8.35), SiO2 (7.13), Al2O3 (2.46), SO3 (2.29) and MgO (1.81) with other oxides in minor quantities. The shale-limestone lithofacies of OHA 2 of the same rock showed CaO (85.90), SiO2 (5.13), MgO (2.56), Al2O3 (1.80), SO3 (1.71), Fe2O3 (1.20) and P2O5 (1.02) with other oxides in minor quantities. OHA 3 of cross-bedded sandstone lithofacies contains SiO2 (52.70), Fe2O3 (14.10), Al2O3 (14.50), MgO (3.74), CaO (9.00), TiO2 (2.54), K2O (1.41) and Cl (0.12) with other oxides in minor quantities. For OHA 4 through the XRF indicates Chloride (Cl), CaO and SiO2 contains 79.60%, 0.58% and 3.52%. The samples showed that major component were SiO2, Al2O3, Fe2O3, CaO, MgO and TiO2. The presence of CaO was determined to be deposited on the surface of debris of rocks in the area. It was observed that the occurrence of CaO is amorphous in nature and not crystalline. [ABSTRACT FROM AUTHOR]

The three-dimensional (3D) visualization of geological structures and the dynamic simulation of geological evolutionary processes are helpful when studying the formation of renowned geological features. However, most of the existing 3D modeling software is based on raster models, which are unable to generate smooth geological boundaries. This work proposes a 3D temporally dynamic (i.e., four-dimensional (4D)) modeling method using parametric functions and vector data structures, which can dynamically build geological evolutionary vector models of well-known geological features. First, we extract the typical features of different kinds of geological formations and represent them using different parameters. Next, we select appropriate parametric functions to simulate these geological formations according to the characteristics of the individual structures. Then, we design and develop 4D vector modeling software to simulate the geological evolution of these features. Finally, we simulate an area with complex geological structures and select six real-world geological features, such as the Piqiang Fault in China and the Eye of the Sahara in the Sahara Desert, as case studies. The modeling results show that a regional geological evolutionary model that contains smooth boundaries can be established within minutes using this method. This work will support studies into the formation of renowned geological features in terms of providing visualizations and will make the representation of geological processes more intuitive in 3D. [ABSTRACT FROM AUTHOR]

The utilization of geological formations, distinguished by natural porosity and permeability and protected by low-permeability caprock, has emerged as an effective strategy for carbon dioxide (CO2) storage. This method significantly contributes to mitigating anthropogenic greenhouse gas emissions and addressing the challenges of climate change. Recent research has unveiled the potential of CO2 to enhance geothermal heat energy extraction in geothermal reservoirs by acting as a subsurface heat exchange fluid. This review paper explores the viability of CO2 in augmenting geothermal heat energy extraction, comparing it to conventional water-based geothermal systems. Special emphasis is placed on CO2 plume geothermal (CPG) systems, characterized by rapid deployment and long-term utilization of geothermal energy resources. With the overarching objective of establishing net-zero energy communities, the analysis of such systems offers a comprehensive understanding of their features, providing a fresh perspective on extracted energy within the context of energy supply in integrated, sustainable energy in built systems. Notably, these systems demonstrate efficacy in meeting the power requirements of an energy community, spanning both distinct heating and electricity needs. However, the key challenge lies in selecting suitable locations. This scientific review aims to comprehend the characteristics of CPG under specific temperature and pressure conditions while optimizing subsurface permeability. This insight is pivotal for identifying future locations for CPG operations with the intent of powering small energy communities. [ABSTRACT FROM AUTHOR]

Carbon Dioxide (CO 2) emissions from fossil fuel consumption have caused global warming and remain challenging problems for mitigation. Underground Hydrogen Storage (UHS) provides clean fuel and replaces traditional fossil fuels to reduce emissions of CO 2. Geological formations such as depleted oil/gas reservoirs, deep saline aquifers and shale formations have been recognized as potential targets to inject and store H 2 into the subsurface formations for large-scale implementation of CCS and UHS. However, the presence of H 2 with cushion gas at different fractions under different geo-storage conditions, which can influence Hydrogen's flow properties, was not investigated widely. Until now, studies of interfacial properties between water and a mixture of cushion gas (CO 2 , N 2 or CH 4) in the presence of H 2 are very limited or unavailable data in experiments and simulations. In this study, many predictions by using molecular dynamics simulation were conducted to predict the interfacial tension (γ) for the systems of H 2 /CO 2 /H 2 O, H 2 /N 2 /H 2 O and H 2 /CH 4 /H 2 O at different pressures, temperatures, and fractions of cushion gases A comparison between the predicted γ results from the simulation and previous research were also made. The findings of this study indicated that γ of H 2 /CO 2 /H 2 O, H 2 /CH 4 /H 2 O, and H 2 /N 2 /H 2 O, as a function of pressure, temperature, and fraction of H 2 , decreased with increasing pressures and temperatures and increased with increasing H 2 % in the mixture. Additionally, an extending or new γ data in simulation for the CO 2 /H 2 /H 2 O, N 2 /H 2 /H 2 O and CH 4 /H 2 /H 2 O systems from this study were reported and support evaluating the stability and storage capacity of H 2 combined with the cushion gas in geological formations. Furthermore, it can contribute to de-risking and proceeding safely and efficiently for the large-scale implementation of Underground Hydrogen Storage. • Predict interfacial tension between water and cushion gas (CO 2 , N 2 , and CH 4) in the presence of H 2. • Interfacial tension, as a function of pressure and temperature, decreased with increasing pressure and temperature. • Interfacial tension, as a function of H 2 fraction, increased with increasing the fraction of H 2 in the mixture gas. • Investigate the effects of cushion gas on the stability and storage capacity of H 2 in geological formations. [ABSTRACT FROM AUTHOR]