Search Results (206)

This paper presents an updatable stochastic geometallurgical framework that integrates geochemical compositions and processing-related variables within a unified spatial modeling and data assimilation workflow. The framework combines multivariate geostatistical simulation with real-time updating based on the Ensemble Kalman Filter, allowing stochastic realizations to be sequentially adjusted as new production data become available. The methodology accounts for geological uncertainty, compositional constraints, and multivariate dependencies. This is achieved by combining the isometric log-ratio transformation with flow anamorphosis within a multivariate Gaussian framework. As a result, compositional geochemical variables and metallurgical responses can be updated consistently while preserving their physical and statistical relationships. The framework is demonstrated using the Gol Gohar iron ore deposit as a case study. Exploration drill hole data and production-scale blast hole measurements are assimilated within an ore control context. The results indicate that the update-enabled simulation approach reduces prediction errors and spatial uncertainty, while capturing complex, non-linear relationships among geometallurgical variables. The framework is generic and can be applied to other deposits where real-time integration of geological, geochemical, and processing information is needed to support operational decision-making. Full article

Chemical complexity is not a nuisance to be minimized in origin of life research, it is an enabling condition. This second edition of the Special Issue on the Origin of Life in Chemically Complex Messy Environments gathers contributions that embrace multicomponent mixtures, dynamic geochemical settings, and nonequilibrium processes. The papers collected here survey surface hydrothermal routes to reactive nitriles, groundwater evolution of alkaline lakes, and transition metal sulfide-driven amino acid and amide formation without cyanide. They report one pot nucleoside and nucleotide synthesis from formamide over cerium phosphate, review non aqueous organophosphorus pathways, and probe peptide rich mixtures and formose type networks under serpentinization associated minerals. The issue also advances conceptual frameworks, including atmospheric photochemical signatures for biosignature discrimination, the role of chiral mineral surfaces in enantioseparation, and computational simulations of the origin of LUCA. Together, these studies position messy chemistry as a crucible that turns chemical diversity and environmental heterogeneity into routes toward organization and function. Full article

The “bauxite gas reservoir” in the Ordos Basin represents a novel exploration domain, yet the mechanisms governing its widespread aluminous fracture fillings remain unclear. This study integrates core observation, thin-section analysis, geochemical simulation, and rock physics to investigate the formation and impact of these fracture systems. Results identify a characteristic filling evolutionary sequence of “wall-lining film → oolitic/globular → plug-like → vermicular.” Geochemical simulations confirm that increasing pH and decreasing Eh driven by water–rock interactions are the key drivers for aluminous mineral precipitation. A distinct well log response model characterized by high GR, DEN, and CNL values coupled with low AC and RT is established for effective identification. Seepage experiments reveal that while Al–Si colloidal fracture fillings reduce permeability, they act as natural proppants to preserve effective flow channels, acting as a crucial high-permeability network for gas migration despite the mineral occlusion. These findings refine the accumulation theory for bauxite series reservoirs and provide geological evidence for deep tight gas exploration. Full article

Utilizing saline aquifers for carbon mineralization has proven to be a reliable approach for CO₂ storage. However, less attention has been given to CO₂ mineralization and geomechanical response at engineering durations and spatial scales. The objective of the study is to evaluate the feasibility of a potential CO₂ sequestration site in the Ordos Basin, located at a depth of approximately 1100 m, using the CMG-GEM numerical simulator. A coupled hydraulic–mechanical–chemical model was formulated, accounting for multiphase fluid flow, geochemical reactions, and geomechanical response. The simulation results indicated the following: (1) When CO₂ is injected into a saline formation, it can react with minerals. These chemical reactions may lead to the precipitation of certain minerals (e.g., calcite, kaolinite) and the dissolution of others (e.g., anorthite), potentially affecting the porosity and permeability of the storage formation; however, the study found that the effect on porosity is negligible, with only a 1.2% reduction observed. (2) The extent of ground uplift caused by CO₂ injection is strongly influenced by the injection rate. The maximum vertical ground displacements after 25 years is 6.1 cm at an injection rate of 16,000 kg/day; when the rate is increased to 24,000 kg/day, the maximum displacement rises to 9.4 cm, indicating a 54% increase. Full article

Effective drillhole placement is critical to the success of mineral exploration, particularly in brownfield settings where subsurface information remains sparse despite the availability of data from adjacent, previously explored areas. To address the challenges of uncertainty in resource estimation and the high cost of drilling, we present a drilling sequence optimization framework guided by geophysical and surface geochemical data. The framework integrates statistical learning and geostatistical simulation to construct a set of prior models of intrusion and nickel grade distribution. These models are used to quantify the expected reduction in uncertainty for each potential drillhole by evaluating their corresponding Efficacy of Information (EOI). This approach allows the sequential selection of drillhole locations that maximize information gain while managing exploration risk. We apply the methodology to a case study in the Curaçá Valley, Brazil, where prior data from a well-characterized nearby zone inform predictions in the adjacent target area. The results demonstrate that incorporating prior geological knowledge from nearby areas into the drilling strategy can significantly improve targeting efficiency and reduce uncertainty in early-stage brownfield exploration. Full article

Lithuania covers the deepest parts of the Baltic basin and contains many reservoirs that have been explored for Hydrocarbon production and gas storage projects, including CO₂ and hydrocarbon gas storage. Studies have also been conducted to assess the storage potential of these reservoirs for gases like CO₂ and Hydrogen. In the studies, four saline aquifers, including Syderiai, Vaskai, and D11, and depleted hydrocarbon reservoirs in the Gargzdai structure were evaluated for potential CO₂ storage. However, the long-term fate of these gases’ migration at the field scale has not been reported previously. In response to the existing gap, this study aims to evaluate the risks and challenges associated with subsurface CO₂ and Hydrogen storage by conducting numerical simulations at two injection rates, of fluid migration, pH variations, and geomechanical responses using the tNavigator platform, complemented by laboratory experiments on outcrops representative of Syderiai formation, to achieve a detailed understanding of geochemical interactions between rocks and fluids. The results reveal distinct gas-specific behaviors: CO₂ exhibits enhanced solubility trapping, density-driven convective mixing, and pronounced pH reduction, whereas Hydrogen demonstrates rapid buoyant migration, higher pressure buildup, and negligible geochemical reactivity. Both gases demonstrate short-term storage viability in the Syderiai aquifer under the modeled conditions, with pressure and total vertical stress remaining below the bottom-hole pressure limit of 450 bars. This integrated simulation and experimental study enhances our understanding of Lithuanian reservoirs for the safe, long-term storage of both CO₂ and Hydrogen. Full article

In this study, we developed a novel water quality model that integrated hydrodynamic, solute transport, and geochemical reactions processes. This model was built upon the open-source ELCIRC hydrodynamic model, the TVD-format solute transport model, and the PhreeqcRM geochemical reaction engine. The accuracy of the model was rigorously validated using a 2D chain decay analytical solution, demonstrating its capability to accurately simulate water flow, solute transport, and chemical reactions. To evaluate the practical applicability of the model, case studies involving the 2012 Huaihe River benzene leakage accident and the acetic acid leakage accident in the Gulei sea area were simulated. Findings indicate that the model effectively captures the diffusion and attenuation dynamics of the benzene contamination plume. Furthermore, it accurately depicts the reaction–diffusion interaction with seawater following acetic acid release. Notably, the versatility and flexibility of the model were further demonstrated by its ability to simulate a wide range of pollutants and their associated biochemical processes. This addresses the limitations of existing water quality models and provides a powerful tool for environmental monitoring and assessment. The results of this study offer valuable insights for improving water quality management and emergency response strategies in the face of environmental pollution incidents. Full article

Xicheng is an important Chinese area enriched in lead–zinc polymetallic ore concentration area. Since the 1970s, substantial research achievements have been made in various domains, including the geological and geochemical characteristics of the deposits, metallogenic chronology, features of the marine basin during the initial mineralization stage, enrichment and precipitation of lead–zinc and other metallic ions, ore genesis, and metallogenic simulation experiments. Among these, the most representative findings focus on exhalative sedimentary reformation and the complexation of organic matter with lead–zinc metal elements during sedimentary processes. This review discusses the formation and evolution of sulfur-containing organic matter, especially H₂S, under Thermal Decomposition of Sulfate (TDS), Bacterial Sulfate Reduction (BSR), and Thermochemical Sulfate Reduction (TSR) conditions, and further summarizes the general characteristics of organic matter and lead–zinc (and other metal elements) adsorption–complexation–reduction. Subsequent research on organic lead–zinc mineralization in the Xicheng area has been grounded in ore deposit geology and geochemistry, adopting the perspective of organic fluids. These studies focus particularly on the formation process of Pb–Zn organic complexes and analyze the various stages and mechanisms of mineralization based on the characteristics and evolution of organic matter. This approach provides new insights for understanding both the general features and the unique attributes of lead–zinc mineralization in the Xicheng area. Full article

Unconventional shale oil reservoirs, characterized by ultra-low porosity and permeability, severely constrain oil recovery. CO₂-enhanced oil recovery (CO₂-EOR) following hydraulic fracturing is an effective approach that combines incremental oil recovery with long-term CO₂ storage. However, CO₂ transport in the fracture–matrix system is complex, especially when molecular diffusion and geochemical reactions are coupled. This study conducts numerical simulations on a representative shale reservoir in the Ordos Basin, incorporating both mechanisms under post-fracturing injection–soaking conditions. The results show that molecular diffusion enhances CO₂ mass transfer across the fracture–matrix interface, increasing the final CO₂ sweep efficiency by 0.17 percentage points relative to convection alone, whereas geochemical reactions reduce it by about 0.3 percentage points. When both mechanisms coexist, the net effect is a decrease of approximately 0.2 percentage points in CO₂ sweep efficiency. In contrast, pressure sweep efficiency differs by less than 0.5 percentage points among all cases and stabilizes near 47%, suggesting that pressure propagation is only weakly affected by diffusion and reactions. Sensitivity analysis reveals that, among operational parameters, injection pressure and injection rate strongly affect CO₂ sweep efficiency, whereas soaking time governs pressure propagation. Among reservoir parameters, permeability has the most pronounced influence on both CO₂ and pressure sweep efficiencies, followed by temperature, while initial reservoir pressure has minimal impact. This work quantitatively elucidates the coupled roles of molecular diffusion and geochemical reactions in shale reservoirs and provides practical guidance for optimizing post-fracturing CO₂-EOR operations. Full article

Modeling the water cycle in the critical zone requires understanding interactions between the soil–vegetation–atmosphere compartments. Mechanistic modeling of soil water flow relies on the accurate determination of hydrodynamic parameters that control hydraulic conductivity and water retention curves. These parameters can be derived either using pedotransfer functions (PTFs), using soil properties obtained from field samples, or through inverse modeling, which allows the parameters to be adjusted to minimize differences between simulations and observations. While PTFs are widely used due to their simplicity, inverse modeling requires specific instrumentation and advanced numerical tools. This study, conducted at the Hydro-Geochemical Environmental Observatory (Strengbach forested catchment) in France, aims to determine the optimal hydrodynamic parameters for two contrasting forest plots, one dominated by spruce and the other by beech. The methodology integrates granulometric data across multiple soil layers to estimate soil parameters using PTFs (Rosetta). Water content and conductivity data were then corrected to account for soil stoniness, improving the KGE and NSE metrics. Finally, inverse parameter estimation based on water content measurements allowed for refinement of the evaluation of α, Ks, and n. This framework to estimate soil parameter was applied on different time periods to investigate the influence of the calibration chronicles on the estimated parameters. Results indicate that our methodology is efficient and that the optimal calibration period does not correspond to one with the most severe drought conditions; instead, a balanced time series including both wet and dry phases is preferable. Our findings also emphasize that KGE and NSE must be interpreted with caution, and that long simulation periods are essential for evaluating parameter robustness. Full article

This paper presents a comprehensive study on the feasibility and implications of a CO₂ injection simulation in the Syderiai deep saline aquifer of Lithuania, focusing on leakage, geo-mechanical aspects, and geo-chemical aspects. The Syderiai aquifer, characterized by its sandstone formation covered by shaly rocks, is considered a potential site for CO₂ geological storage in Lithuania. Using 3D mechanistic models developed in T-navigator software, we conducted extensive simulations to analyze CO₂ storage behavior and associated impacts. The leakage study examines various scenarios to assess the impact of fracture permeability, layer-wise heterogeneity, and fracture position on CO₂ injection and leakage volumes. Results indicate that while fracture permeability influences CO₂ migration dynamics, its impact on both free and dissolved CO₂ leakage volumes is minimal, highlighting that leakage behavior is more dependent on the presence of fractures than their permeability. Geo-mechanical analysis reveals the effects of CO₂ injection on the bulk modulus and shear modulus of sandstone and shale formations, highlighting changes in compaction and cementation. The geo-chemical study was performed using TOUGHREACT software V4.13-OMP to investigate the distribution of pH, porosity change, and free CO₂ over 1000-years following 10-year CO₂ injection. Results demonstrate the acidifying effect of CO₂ injection and its implications for the caprock–reservoir interface over time. The findings offer valuable perspectives on the feasibility and consequences of CO₂ geological storage in the Syderiai deep saline aquifer, highlighting the importance of incorporating leakage, geo-mechanical aspects, and geo-chemical aspects for implementing efficient CO₂ storage. Full article

Illite plays a critical role in diagenetic processes of sedimentary rocks, influencing geochemical evolution, reservoir quality, and fluid flow pathways. This study experimentally investigated the hydrothermal transformation of kaolinite to illite using sandstones from the Upper Ordovician Quwarah Member of Qasim Formation, northwest Saudi Arabia. Experiments were performed to simulate burial diagenesis involving illitization using three fluid systems: a synthetic solution (0.2 M KCl and 0.5 M MgCl₂), natural Red Sea water, and modified Red Sea water (0.2 M KCl and 0.5 M MgCl₂ + Red Sea water) at different temperatures (80 °C, 150 °C, 200 °C, 250 °C). Analysis included thin-section petrography, scanning electron microscopy, and X-ray diffraction, whereas the elemental compositions of the experimental solutions were analyzed using ICP-MS and Ion Chromatography. At 80 °C and 150 °C, kaolinite underwent dissolution without significant mineralogical changes. At 200 °C, continued kaolinite disaggregation and dissolution produced smectite and mixed smectite–chlorite/illite layers, indicating early transformation pathways. At 250 °C, fluid chemistry exerted strong control on clay minerals. The synthetic solution formed smectite with minor chlorite and illite; Red Sea water favored well developed smectite; the modified Red Sea water promoted well-developed illite due to increased potassium availability. The experiments show illitization is strongly temperature dependent and primarily controlled by potassium activity in fluids. The study provides insights into clay mineral evolution with different diagenetic conditions, which can be useful to evaluate diagenetic impact on reservoir qualities. Full article

Compressed air energy storage in aquifers presents a promising approach for large-scale energy storage, yet its implementation is complicated by geochemical reactions, such as pyrite oxidation, which can impact reservoir integrity and operational efficiency. This study numerically investigates the evolution of reservoir characteristics and geochemical processes during CAESA operations to address these challenges. Using the TOUGHREACT simulator, we developed one-dimensional and two-dimensional reactive transport models based on the Pittsfield aquifer field test parameters to simulate coupled thermal-hydrological–chemical processes under varying injection rates, temperatures, reservoir depths, and operational cycles. The results demonstrate that higher injection rates induce greater near-well pressure buildup and extended thermal zones, while deeper reservoirs exhibit abrupt declines in pressure and gas saturation due to formation constraints. Geochemical analyses reveal that pyrite oxidation dominates, leading to oxygen depletion, groundwater acidification (pH reduction), and secondary mineral precipitation, such as goethite and hematite. These findings underscore the critical interplay between operational parameters and geochemical reactions, highlighting the need for optimized design to ensure long-term stability and efficiency of aquifer-based energy storage systems. Full article

Understanding the mechanisms of mineral dissolution at the atomic scale is crucial for interpreting geochemical processes in soils and sediments, particularly those involving clay minerals. This study addresses the dissolution of pyrophyllite, a model dioctahedral phyllosilicate, under acidic conditions by employing Density Functional Theory (DFT) to simulate protolysis reactions at four distinct edge surfaces ({100}, {010}, {110}, and {130}). Molecular cluster models were constructed for each edge, and the interactions of protons and hydronium ions with various oxygen sites were systematically analyzed. The results demonstrate that bridge oxygens, especially those coordinated to one silicon and two aluminum atoms, are the most reactive sites, undergoing significant bond breaking and structural distortion upon protonation, while hydroxyl groups mainly accommodate structural changes without initiating dissolution. The {110} edge was found to be the least reactive, whereas the {100}, {010}, and {130} edges exhibited the highest reactivity. Hydronium ions produced similar or greater structural changes compared to protons, with water molecules forming hydrogen bonds with the resulting structures. These findings confirm that protonation of bridge oxygens is the rate-limiting step in phyllosilicate dissolution, and that octahedral cations are released preferentially over tetrahedral ones. These findings are consistent with the conclusions drawn from the dissolution experiments. This study provides atomistic information on the dissolution mechanisms of clay minerals at a scale that exceeds the capabilities of dissolution experiments, emphasizing the importance of edge reactivity relative to extensive basal surfaces and the role of water in proton transfer and facilitating protolysis reactions. Full article

Geochemical exploration offers a cost-effective means of identifying subsurface oil and gas accumulations through the detection of volatile organic compounds (VOCs), which serve as markers of underlying hydrocarbon systems. These indicators may appear as visible macroseeps or as subtle microseepage, detectable only through advanced analytical methods. A widely used approach involves deploying specialized sorbent materials a few meters below the surface to capture VOCs, followed by gas chromatography–mass spectrometry (GC-MS) for analysis. Given the range of available adsorbents, selecting materials with optimal performance is critical. We developed a laboratory method to evaluate the adsorption affinity of various commercial and custom-made sorbents toward hydrocarbon mixtures, including nitrogen-, oxygen-, and sulfur-containing derivatives. Using natural crude oil in a simulated microseepage setup, we screened a library of sorbents to identify those most effective for capturing oil-related markers. The complexity of the VOC mixtures required advanced separation, for which we employed two-dimensional high-resolution gas chromatography with time-of-flight mass spectrometry (HR-GCxGC-TOF-MS). The screening revealed clear differences in sorbent performance based on analyte diversity and concentration, assessed through thermal desorption/HR-GCxGC-MS and BET surface area analysis. Two custom sorbents, composed of carbon nanomaterials, outperformed a commercial benchmark in both adsorption capacity and analyte diversity, making them strong candidates for future field deployment in surface geochemical exploration. Full article