The deep subsag zones of rift lake basins remain underexplored, but are critical areas for the discovery of strategic resource plays. Thus, understanding the hydrocarbon accumulation systems in these zones is essential.

This study focuses on the deep subsag zone of the Huanghua Depression and conducts an in-depth analysis of the sedimentary, reservoir, source rock, and trap conditions to elucidate the sandstone distribution mechanisms, reservoir development processes, and hydrocarbon accumulation models in the deep subsag zone.

The deep subsag zone of the Cangdong Sag, located near the basin margin and close to the provenance area, has a source-fault-sag configuration that promotes fan-delta deposition. This zone exhibits a spatial configuration of "sandstone-mudstone interlayers with lower source and upper reservoir" and a temporal pattern of "early oil charge and early deep burial". In contrast, the deep subsag zone of the Qikou Sag, situated farther from the provenance area at the basin center, follows a source-trench-slope configuration conducive to far-shore submerged fan deposition. Its spatial configuration is "mudstones covering sandstones with three-dimensional oil charging", and its temporal configuration is "late oil charge and late deep burial". Both zones are rich in mudstones and sandstones, with high-quality source rocks that exhibit high thermal maturity and are conducive to large-scale hydrocarbon generation. The prevailing conditions favor the development of large sand bodies. Three key factors (dominant minerals, organic acid dissolution, and anomalous overpressure)play a critical role in the formation of effective reservoirs. The deep subsag zones also offer superior trapping conditions, primarily in the form of lithological hydrocarbon reservoirs, characterized by source-reservoir coupling, proximal source charging, and zonal enrichment.

This study highlights the substantial exploration potential of the deep subsag zones in faulted lake basins, providing valuable insights for hydrocarbon exploration in these areas.

The Cambrian-Ordovician buried-hills in the Huanghua Depression, Bohai Bay Basin, have shown petroleum indications, but exploration breakthroughs remain elusive. The reservoir-forming factors, genetic types, and exploration potential within these buried-hill systems are still unclear.

A systematic analysis of the reservoir-forming conditions was conducted using newly acquired 3D seismic data, drilling geology, well log, and geochemical data. This study further explores the genetic types of reservoirs and identifies potential exploration targets.

The research shows the following findings: The Huanghua Depression hosts two sets of hydrocarbon source rocks: The Third Member of the Paleogene Shahejie Formation (Es₃) and the Upper Paleozoic Carboniferous-Permian, which provide abundant hydrocarbon sources for buried-hill reservoirs. Two types of genetic traps are identified within the buried-hill systems: Anticlinal traps controlled by basement fold deformation and fault-nose traps governed by basement fault tilting. Regional compressional stress during the Indosinian-Early Yanshanian orogeny, followed by extensional tectonism during the Late Yanshanian-Himalayan period, provided the foundation for buried-hill formation. Lithology, dolomitization, dissolution, and faulting jointly control three dominant reservoir types: Matrix pores, dissolution vugs, and fracture networks, which together created favorable pore spaces within the buried-hill systems. By analyzing the source-reservoir configurations in the Cambrian-Ordovician buried-hill systems, three reservoir-forming models are proposed: Dual-source hydrocarbon supply-negative inversion anticline type, single-source hydrocarbon supply-positive inversion anticline type, single-source hydrocarbon supply-tilting fault-nose type. The Chenghai and Wangguantun buried-hill systems have the most favorable reservoir-forming conditions. Undrilled intra-hill traps in these areas have significant exploration potential and are recommended as priority targets for future buried-hill exploration.

The research results can provide theoretical guidance for the buried-hil exploration.

The hidden buried-hills in the Shulu Sag of the Bohai Bay Basin face challenges such as difficult trap identification and unclear reservoir conditions, leading to limited progress in buried-hill exploration over recent years. Consequently, it is essential to reorganize the exploration strategies.

This study is guided by geological modeling and emphasizes the integration of seismic processing and interpretation. The aim is to deepen the understanding of fault interpretation and reservoir formation conditions within the coverage area of the Lower Paleozoic carbonate rocks on the western slope of the Shulu Sag. A new model of buried-hill reservoir formation, termed "fault trough erosion ditch lateral obstruction" is proposed.

The research demonstrates that processing, including velocity simulation, effectively identifies the top surface of the buried-hill. Additionally, anisotropic pre-stack depth migration technology enhances the imaging quality of the buried-hill's interior, while low-pass filtering clarifies internal fault breakpoints. Over 50 new faults have been identified on the top surface of the slope belt buried-hill, and more than 30 favorable traps within the Ordovician system have been identified and confirmed, resulting in an increased trap area of nearly 20 km². Several wells, such as Well JG21x, have achieved high-yield oil flows within the buried-hill. The novel reservoir formation model challenges previous notions that the buried-hills on the western slope of the depression were non-exploratory targets. The newly proposed model suggests these reservoirs are shallow-buried with high productivity, becoming a promising area for exploration in North China. High-quality seismic data have been obtained through combined seismic data processing and interpretation. Guided by the new geological model, a fresh understanding of buried-hill reservoir formation has been developed.

This integrated approach provides valuable reference insights for exploration in highly mature areas with complex buried-hills.

The geochemical characteristics and sedimentary environment of source rock in the Middle Section of Es₁ in the Binhai slope have been insufficiently studied, limiting the potential for expanding hydrocarbon exploration into offshore areas.

In this study, newly drilled source rock samples from the Binhai slope were analyzed to systematically investigate the geochemical characteristics, depositional environments, and developmental models of source rock in the Middle Section of Es₁. Techniques such as petrographic pyrolysis, gas chromatography-mass spectrometry (GC-MS) of saturates, and elemental logging were employed.

The findings show that source rock in the Middle Section of Es₁ in the Binhai slope predominantly contains type Ⅱ₁-Ⅱ₂ kerogen, with total organic carbon w(TOC) contents ranging from 0.21% to 8.61%, an average w(TOC) of 2.41%, and an average (S₁+S₂) of 9.73 mg/g. The source rock can be classified as good to high quality. The source rock maturity ranges from low to mature, with R_o values between 0.58% and 1.32%. The organic matter is derived from a mixture of terrestrial plants and aquatic organisms, and the source rock formed in a freshwater environment with minimal oxidizing and reducing conditions. During the period of source rock deposition, the lake water was relatively deep, the climate was warm and humid, and the paleo-productivity was high.

The source rock in the Middle Section of Es₁ in the Binhai slope contains high-quality organic matter with abundant organic content and moderate maturity. The sedimentary environment was conducive to the enrichment and preservation of organic material, indicating that the source rock have strong hydrocarbon generation potential and exploration value.

The Third Member of the Dongying Formation in the deep subsag area of the Qikou Sag is primarily characterized by semi-deep to deep lacustrine subfacies, with extensive development of gravity-flow sandbodies. Clarifying the sedimentary characteristics and formation mechanisms of these gravity-flow sandbodies can provide theoretical support for petroleum exploration.

By integrating the high-precision seismic, logging, core, and thin section data, we analyzed the genetic mechanism of gravity-flow sandbodies within the deep lake setting. Focusing on the Third Member of the Dongying Formation in the Qikou Sag, we also summarized the distribution pattern of the gravity-flow deposition system in the deep subsag area of the Qikou Sag.

The results indicate that during the deposition of the Third Member of the Dongying Formation, the activities of basin boundary faults and internal sedimentary slope folds induced the occurrence of collapse in the sandbodies of the barided river delta front and the vertically superimposed gravity-flow deposits within the deep subsag. The gravity-flow deposits in this area were subdivided into six lithofacies, corresponding to three genetic types: Sandy debris flows, muddy debris flows, and turbidity currents. The sandbodies exhibit well-sorted grains, low matrix content, and typical characteristics of slump-type gravity-flow deposits. Spatial analysis of lithofacies assemblages revealed a planar distribution pattern characterized by proximal sandy debris flows transitioning to turbidity currents and distal muddy debris flows. Among these, the sandy debris channels have the best reservoir properties and represent the most favorable reservoir facies in the deep subsag area. In contrast, the turbidity sandstone reservoirs have relatively poor physical properties.The coastal slope demonstrates a spatial-temporal matching relationship of far-source-gully-long-slope-appropriate, which possesses the potential for forming large-scale gravity-flow-deposited sandbodies.

The research results can provide a reference for oil and gas exploration in the deep subsag.

China has abundant continental shale oil resources, which serve as an important strategic substitute for conventional petroleum. The factors that influence shale reservoir development are crucial to understanding the enrichment mechanism of shale oil. This study focuses on the Upper Fourth Member of the Shahejie Formation, utilizing XRD, gas adsorption, high-pressure mercury injection, FE-SEM, and FIB-SEM to identify lithofacies types, characterize shale storage space and structures, and explore the factors influencing pore development in the shale.

The results show that: ①Five primary lithofacies types are developed in the study area: Organic-rich laminated calcareous shale, organic-rich laminated mixed shale, organic-rich layered mixed shale, organic-rich massive calcareous shale, and organic laminated calcareous shale. ②The main types of reservoir spaces include intergranular pores, dissolution pores, intergranular pores, and microfractures, with organic pores being minimally developed. Significant differences in pore structure are observed across different shale types, with organic-rich laminated shale showing larger pore volumes. ③The abundance of organic matter and sedimentary structures (such as laminations) play a significant role in controlling shale reservoir properties. Organic acid dissolution leads to the formation of dissolution pores, enhancing reservoir performance. However, excessive organic matter abundance increases shale plasticity, hindering pore preservation. Laminated structures enhance reservoir properties, with felsic laminations showing the best reservoir properties, followed by clay laminations, and coarse calcite laminations having the poorest reservoir properties.

The research reveals the characteristics and controlling factors (organic matter abundance and laminations) of shale reservoirs in the Upper Fourth Member of the Shahejie Formation, providing valuable insights for the development of continental shale oil in the Bohai Bay Basin.

The vertical and horizontal zonation of this volcanic weathering crust reservoir and the distribution patterns of favorable reservoirs remain unclear, hindering further exploration of volcanic oil and gas in the area. Therefore, an in-depth analysis of this unique volcanic weathering crust reservoir is necessary.

This study analyzes the formation process of the weathered volcanic crust, its vertical and horizontal zonation, and favorable exploration directions, based on data from well logging, drilling, lithology, and field geological profiles.

The evolution of the Carboniferous volcanic weathering crust in the study area can be divided into four stages: The initial fissure-type volcanic eruption stage, the intermittent volcanic eruption stage, the renewed volcanic activity stage, and the weathering crust formation stage at the top of the Carboniferous volcanic layer. The volcanic weathering crust reservoir primarily formed during the intermittent volcanic eruption stages, with weathering materials consisting of volcanic rocks from the eruption periods and sedimentary rocks associated with volcanic activity. Multiple volcanic eruption and weathering episodes resulted in the formation of multilayered weathering crusts within the volcanic rocks. Each weathering crust episode can be divided, from bottom to top, into a bedrock layer, a fracture layer, a sandy layer, and a sedimentary layer. Among these, the fracture and sandy layers exhibit better reservoir properties and are the main oil and gas reservoirs. Horizontally, the weathering crust is divided into a dissolution platform area, dissolution slope area, and dissolution depression area. The dissolution slope area, where fractures and dissolution pores are most developed, represents the most favorable exploration target. In contrast, the dissolution depression area experiences severe cementation, resulting in the poorest reservoir properties.

The research results can provide important guidance and insights for the exploration of volcanic oil and gas.

The interaction between CO₂-rich fluids and sandstone is one of the main mechanisms of secondary pore generation in sandstone reservoirs. The L gas field, located in Lishui Sag, is not only characterized by high CO₂ content but also by the enrichment of ammonium dawsonite in its main production layers.

This study systematically analyzes the rock and mineral composition, physical properties, carbon and oxygen isotopes, and related geochemistry to reveal the source, formation time, filling intensity of CO₂, and its influence on the reservoir in the L gas field.

The results are as follows: (1) In the reservoir of the study area, authigenic carbonate minerals are primarily iron dolomite, sodium aluminate, and iron calcite, followed by dolomite, siderite, and calcite. (2) Ammonium dawsonite is vertically concentrated in middle and lower parts of the Lower Member of Mingyuefeng Formation, where the CO₂ content is high. (3) CO₂ is mainly of inorganic origin, with contributions from both mantle and crust sources. (4) There were two phases of CO₂ charging. The first filling event occurred around 57 Ma during the Late Paleocene and was the major charging period. The second filling event occurred during the Early Miocene, about 18 Ma. (5) The timing and intensity of CO₂ charging are key factors determining its impact on the reservoir. Due to the low content of rigid particles in the L gas field, the reservoir is prone to compaction, and the dissolution is not strong. Additionally, the geothermal gradient is high, and the organic acid window is narrow, limiting the reservoir improvement by organic acids. Early CO₂ filling not only generates carbonate dissolution pores but also enhances the anti-compaction ability of the sand bodies, preserving a certain amount of primary porosity. This process is beneficial for the development of high-quality reservoirs.

The research results can provide reference for oil and gas exploration in the sedimentary basin of the gas field.

Carbonate fault-controlled fracture-cavity reservoirs are present in the Shunbei area of the Tarim Basin, NW China. Existing modeling algorithms struggle to accurately characterize the internal structure. Urgently needed is research on reservoir modeling algorithms that incorporate the internal structural characteristics of the fault-controlled body. This will establish a detailed three-dimensional geological model aligned with geological understanding and clarify the primary reservoir spaces for oil and gas.

In this paper, taking the Shunbei fault zone No.4 as an example, an object-based modeling method is proposed and applied for the first time. Combined with the idea of hierarchical simulation, the fracture plane and the development scale of caves type in the extrusion, pull-apart and translation stress sections are quantitatively characterized. By designing a grille-based reservoir trend line tracking algorithm, the center line that conforms to the development trend of the reservoir is found, and the idea of hierarchical simulation is integrated to describe the fracture plane and the grille-like filling structure model inside the cave type layer by layer. Based on the established geological model, a property model is created using the phase-controlled method. This model is used for reserve calculation and numerical simulation. Preference is given to the fault-controlled body model with only fracture planes. The fit between the calculated fracture plane reserves and dynamic reserves is 96%. The model also fits bottom hole pressure and actual production data, with an error less than 10%. The main reservoir types in the study area include fracture planes, caves type, and disordered bodies. A fault-controlled body contour model is established for different seismic attribute bodies. Logging interpretation identifies fracture plane and cave type internal developments within the bedrock and crush belt, forming an ordered grille structure. Crush belt further divided into breccia belt and fracture belt. An object-based modeling method creates a three-dimensional geological model of the reservoir's grille structure.

The model optimized for fracture plane reservoirs, aligns with drilling and logging data and geological understanding. It provides a reference for guiding oil and gas reservoir development.

Hydrothermal barite deposits are the main exploration targets for barium. The Wuling-Miaoling area, located in the middle part of the Yangtze Craton, contains abundant hydrothermal barite deposits. In recent years, some barite orebodies have been discovered within the interlaminar fracture zone between the Upper Cambrian Loushanguan Formation and the Lower Ordovician Tongzi Formation in the region. These orebodies, which exhibit stable extension, have significant metallogenic potential. However, the genesis of the barite deposits in the Yuqing area is poorly understood, leading to ambiguity regarding further ore exploration.

In this study, we investigate the barite deposits in the Yuqing area and present a metallogenic model based on detailed petrographic observations and major/trace elements and sulfur isotopic analyses.

Results show that the interlayer fracture zone and tensile fractures generated by the silica-calcium interface are the main ore-controlling structures for barite in this area. The geochemistry of barite shows that the δCe of the wall rocks (dolomite) is normal. In contrast, the negative δCe anomaly (mean value is 0.66) in the barite samples indicates that barite was formed under oxidation conditions. The (Cu+Zn) vs. Sr, Y/Ho ratios, and sulfur isotopes suggest that the ore-forming materials (S and Ba) originated from marine evaporites in the Cambrian. Based on previous studies, we propose that the tectonic event drove the migration of basinal fluids, extracting the Ba-rich evaporite strata. The mixing of these fluids with meteoric water led to the precipitation of barite along the interlayer faults (silica-calcium interfaces).

The research results provide an important reference for the exploration of barite deposits.

The "end effect" of ore formation, a crucial topic in deposit geology and field geomechanics, has increasingly drawn attention from researchers and scholars.

The study of the "end effect" in ore formation primarily includes two aspects: The "end effect" of ore-forming structures and the "end effect" of ore-forming fluids. For ore-forming structures, research focuses on the multi-scale "end effect" of ore-controlling structures in different tectonic settings, and their roles in controlling ore fields and ore deposits. This includes studying the structural types, mechanical properties, and rock- and ore-controlling mechanisms at the "ends" of deposit-level ore-controlling structures, the trapping effect of ore-forming fluids, and the location mechanism of ore deposits. These aspects are examined through structural geomechanical analysis of ore fields, combined with structural alteration lithofacies mapping and geophysical probing techniques. For ore-forming fluids, the characteristics can be explored through fluid inclusion studies and isotope/trace element geochemistry. The temporal and spatial evolution of the "end" of ore-forming fluids is studied by the zoning effect, helping reveal how the physicochemical conditions of structures limit the ore-forming process.

By investigating the coupling relationship between the "ends" of ore-forming structures and ore-forming fluids, a comprehensive study of the rock and ore-controlling mechanisms under the "end effect" can be conducted. This, combined with fluid geochemistry, structural analysis of ore fields, and geophysical prospecting techniques, will provide a solid foundation for deep ore prospecting predictions.

This study aimed to clarify the development characteristics of these reservoirs and reduce the risks associated with deep and ultradeep oil and gas exploration.

On the basis of experimental analyses of well logs, thin-section petrography, high-pressure mercury injection, and PVT phase diagrams, the characteristics of tight sandstone reservoirs and the causes of physical property differences were discussed.

The rock types of the Bashijiqike Formation reservoir in the Bozi area, as highlighted in this study, include medium- to fine-grained lithic feldspar sandstone and feldspar lithic sandstone. Notable differences exist in the spatial distributions of carbonate cement content. The original porosity of the medium-fine sandstone reservoirs ranges from 32.4% to 38.1%, indicating that the occurrence of comparable intergranular compaction strengths primarily depends on point-line contacts. The southern reservoirs maintain an average porosity of 8.6% and an average permeability of 3.4×10⁻³ μm². The central reservoirs exhibit an average porosity of 6.53% and an average permeability of 0.65×10⁻³ μm². The average porosity and permeability of the northern reservoirs are 4.9% and 0.62×10⁻³ μm², respectively. Primary intergranular pores dominate the southern reservoirs, whereas residual intergranular pores and dissolution porosity prevail in the northern and central reservoirs. Additionally, superior pore-throat structures characterize the southern region compared with those in the northern and central regions.

The physical properties of the sandstone reservoirs in the Bozi area are controlled by sedimentation, diagenesis, and tectonic processes (including fractures), with carbonate cementation emerging as the principal influencing for late-stage changes in reservoir physical properties. Overpressure, hydrocarbon fluid charging, and fracture development significantly influence carbonate cementation, subsequently causing variations in reservoir physical properties. Greater overpressure, earlier oil and gas charging, and limited fracture filling result in better reservoir properties in southern Bozi than in the northern and central areas.

The Jurassic Yan'an Formation in the southwestern Ordos Basin hosts numerous oil shale deposits associated with coal, as well as some non-associated oil shale. However, detailed studies on the characteristics and sedimentary environment of these oil shales have been limited over the years.

This study analyzed oil shale samples from various wells in the study area, focusing on their industrial indices, geochemistry properties, and sedimentary paleoenvironment. Oil shale was studied using low-temperature retorting, rock pyrolysis, measurement of major and trace elements, and gas chromatography.

The oil-bearing ratio in the study area ranges from 3.8% to 6.7%, with ash content between 44.81% and 75.58%, total sulfur from 0.31% to 2.29%, and the calorific value is 11.95 kJ/g (average value). The logging curves show the characteristics of high gamma, high resistivity, and negative abnormal natural potential, distinguishing the oil shale from coal seams and mudstones. The dominant organic matter type is type Ⅱ₂. The organic matter is abundant, primarily immature to low-maturity, and classified as medium quality, siliceous ash, and extra-low sulfur oil shale. The main elements in the oil shale are SiO₂ (average 48.26%) and Al₂O₃ (average 17.57%), with notable enrichment in micronutrients such as Sr, Th, and U, and depletion in Ni, V, and B. This suggests more potassium-containing minerals and higher stable components in the study area. Based on paleoenvironmental element markers and saturated hydrocarbon chromatography, the organic matter is mainly of mixed origin, with moderate ancient productivity. The sedimentary environment was a warm, humid, continental freshwater depression, with redox conditions playing a key role in organic matter enrichment. A sedimentary evolution model for the oil shale in the Yan'an Formation across varying depositional periods has been established.

These findings provide valuable theoretical guidance and technical support for the exploration and development of the Jurassic oil shale in the southwestern margin of the Ordos Basin.

The provenance of detritus plays a vital role in controlling the development and spatial distribution of the Benxi Formation sandstone reservoir within the Yanchang exploration area.

Based on previous research, this study employed four provenance analysis methods, including detrital zircon U-Pb ages, heavy mineral assemblages, trace elements, and statistical analysis of sandstone gravel size, applied to sand and mudstone samples from 37 wells in the Yanchang exploration area.

The zircon U-Pb age populations exhibited peaks at approximately 1912 Ma and 2425 Ma, corresponding to the northern edge of the North China Craton. Additionally, peaks at 435−447 Ma and 952−976 Ma from five wells are linked to the North Qinling Mountains. Based on these findings, the provenance of sedimentary rocks can be divided into two primary directions: north and south. Furthermore, heavy mineral assemblage analysis showed higher zircon and tourmaline contents in the southwest region. At the same time, rutile was more abundant in the southeast, indicating that the southern source area can be subdivided into the southwest and southeast. Corresponding trace element analysis, notably the Zr/Nb values, supported these divisions, indicating two provenance directions of southwest Longdong and southeast Yuxi. Additionally, the spatial distribution of sandstone gravel diameters indicated a southeast source within the study area.

Comprehensive analysis reveals that the provenance of the Benxi Formation in the Yanchang exploration area stems from three main source regions: northeast (northern basin margin), southwest (Qilian Mountains), and southeast (North Qinling Mountains). The southeastern source is the closest and contributes the most sediments. This study illustrates the three provenance areas of the Benxi Formation and their influence zones, which are significant for predicting the distribution of sand bodies and delineating sedimentary facies in the Yanchang exploration area.

In order to effectively predict and prevent hazardous rock failure and ensure highway transportation safety,

this paper carries out indoor modeling tests on the initiation of dangerous rock collapse under four different operational conditions by means of joint monitoring of acoustic emission and video, and combines the evolution characteristics of acoustic emission signals in the time, frequency, and time-frequency domains, as well as the time-space characteristics of video images, to investigate the initiation mechanism and precursor characteristics of the process of dangerous rock collapse under a variety of different influencing factors.

The study and analysis of the initiation mechanism and precursor characteristics of the process of dangerous rock collapse under a variety of different influencing factors were carried out, and the results showed that, in terms of the initiation mechanism, the main controlling factors of dangerous rock collapse include the shift of the center of gravity of dangerous rock, the decrease of the adhesion between dangerous rock and slope surface, and the increase of the overall downward sliding force of the dangerous rock of the slope and the increase of the limit of the anti-sliding force. Among them, the decrease of bonding force between hazardous rock and slope surface (or mother rock) is the common initiating mechanism of slip type and tipping type collapse, the shift of center of gravity of hazardous rock is mainly the initiating mechanism of tipping type collapse, and the increase of overall downward sliding force of hazardous rock exceeding the limit of sliding resistance is mainly the initiating mechanism of slip type collapse. These three types of main control factors can be used as one of the judgment criteria for the initiation mechanism of actual slope failure. In terms of precursor characteristics, before the collapse of dangerous rocks, there are precursor phenomena such as localized falling blocks and small rock avalanches on the macro level, and the acoustic emission signals mostly appear in the middle and low frequency bands and the main frequency band is wide, and at the same time, the middle and high amplitude and energy signals account for a large number of the signals. Therefore, when multiple single precursor features appear simultaneously in the comprehensive precursor features, it can be used as one of the judgment criteria for the occurrence of actual slope collapse.

The research can provide scientific basis and technical support for the monitoring and early warning of highway slope dangerous rock failure, which can help to improve the effectiveness and reliability of the prevention and control of dangerous rock collapse disaster.

Landslide susceptibility assessment (LSA) plays a vital role in predicting landslide occurrence and potential risks. However, static susceptibility maps are limited in reliability their failure to account for dynamic evolution of landslides. This study aims to enhance landslide susceptibility assessment by incorporating dynamic factors through Sentinel-1A SAR data, which is derived from Songyang County, Zhejiang Province: A resion impacted by Typhoon Megi in 2016.

The methodology involved three key steps. First, D-InSAR technology was used to measure ground deformation before and after Typhoon Megi. A deformation rate of −20 mm/a was set as the threshold to augment the landslide inventory. Second, SBAS-InSAR technology was applied to obtain ground deformation data from November 22, 2015, to March 4, 2017. Third, nine static factors, including terrain, geology, hydrology, and human activities, were combined with vertical and line-of-sight (LOS) of InSAR ground deformation to produce a dynamic landslide susceptibility map using the MIV-BP neural network framework.

The inclusion of dynamic factors, particularly InSAR ground deformation, significantly improved the accuracy of LSA. When these factors were excluded, prediction accuracy decreased from 0.901 to 0.857. Areas with extremely low and low susceptibility were largely unaffected by Typhoon Megi, while regions with steep or elevated terrain experienced an increase in susceptibility, shifting from medium-high to extremely high susceptibility after the typhoon. The changes in the extremely high susceptibility areas closely aligned with the observed ground deformation from InSAR data.

The findings offer valuable insights for geological disaster prevention and mitigation in Songyang County and other regions facing similar extreme weather events in the future.

Reservoir dams are critical infrastructure, and accurately assessing the extent of earthquake-induced damage is crucial for developing rescue operations and post-disaster restoration. This study aims to achieve rapid and accurate assessment of post-earthquake damage in reservoir dam.

Focusing on earthquake damage data from the Wenchuan M_s8.0 earthquake, this research integrates dam structural characteristics and seismic intensity parameters to establish an assessment index system and dataset. The study employs k-nearest-neighbor interpolation for missing values processing and feature correlation analysis. A rapid assessment model for reservoir dam earthquake damage is proposed using gradient boosting algorithm. To optimize parameters of the gradient boosted tree (GBDT) regression algorithm, four hyperparameter optimization methods are implemented: Grid search (GS), particle swarm optimization (PSO), Bayesian optimization (BO), and hyperband search (HS). The models are compared based on performance metrics, including the coefficient of determination (R²), root mean square error (RMSE), and mean absolute error (MAE), and the feature importance of the optimal models is ranked.

The results demonstrate that the BO-GBDT model provides the most rapid and accurate assessment of earthquake damage to reservoir dams, achieving a high R² of 0.99. Feature importance analysis shows that the maximum crack width is the most influential factor. The model demonstrates superior accuracy compared to earth dam damage assessment models based on improved empirical statistical methods, confirming its reliability for rapid post-earthquake damage evaluation of reservoir dams.

The research results provide a reference for the earthquake damage assessment of reservoir dams.

Rainfall-induced group-occurring shallow soil landslides have the characteristics of strong and sudden occurrence and high risk. It is of great significance to build a runout distance prediction model for landslide risk prevention and control.

This study focuses on the "5·27" group-occurring landslide event in Wuping County, Fujian Province, and obtains 131 landslide characteristic data based on pre-disaster and post-disaster remote sensing images, digital elevation model, drone-derived 3D model and field investigation. According to the location of the slip-out point and topographic characteristics, the landslides are divided into the foot slip-out type, the middle slope slip-out type and the cut slope slip-out type. The main factors affecting the runout distance of group-occurring shallow soil landslides were determined by correlation analysis, and the optimal prediction model for the runout distance of three types of landslides was established using stepwise nonlinear regression analysis.

Correlation analysis shows that the height of the sliding source area is the main influencing factor of the runout distance of rainfall-induced group-occurring shallow soil landslides. The established optimal predictive models exhibited a low residual sum of squares (RSS) and an adjusted R² value greater than 0.9, indicating high reliability and precision. Model validation showed that the relative errors between the predicted and actual values were small, with maximum relative errors of 15.6%, 13.5%, and 12.4% for foot slip-out, middle slope slip-out, and cut slope slip-out types, respectively.

This study established a predictive model for the runout distance of rainfall-induced group-occurring shallow soil landslides based on statistical analysis, providing a scientific basis for landslide disaster prevention in similar regions. While the models exhibit high accuracy, their applicability might be limited by the localized data source. Future research should expand sample diversity and incorporate additional influencing factors to enhance model generalizability.

The landslide in Yuanshan Village, Huangmei County, Hubei Province, represents a granite residual soil avalanche debris flow with complex and abrupt movement dynamics influenced by geological conditions. This study investigates the kinematic mechanisms of such landslide-debris flows in mid-low mountainous areas by analyzing the motion process of this specific event.

Through the field geological survey, the movement process of the landslide debris flow was analyzed based on UAV aerial photography, digital elevation model (DEM), on-site investigation, geological data analysis, and numerical simulations.

The results show that the maximum accumulation thickness of the avalanche is 6 m during the movement process. The peak velocity reaches 17 m/s at t=10 s. The actual peak velocity should be larger and appears when the slip source area begins to be unstable. The whole movement process could be divided into three stages: during the first 30 s, the granite residual soil lost its stability, which resulted in the initiation and acceleration of the debris flow at the first-level platform; in 30-70 s, affected by the terrain, the debris flow was accelerated for the second time. A part of the debris flow changed its flow direction and destroyed the buildings in Yuanshan Village. From 70 s to 130 s, the debris flow decelerated and accumulated, during this stage the buildings were buried and accumulated by the debris flow.

This study can provide a reference for the prevention and control of similar disasters.

To provide data support for disaster prevention, mitigation and risk management in Zhidan County, while providing reference for risk assessment in similar regions and addressing the research gap in collapse and landslide risk assessment that neglects cumulative rainfall impacts, this study conducted risk assessment under four different rainfall conditions: 10, 20, 50 and 100 years recurrence intervals.

Using Zhidan County as the study area with grid unit as evaluation element, we selected eight evaluation factors through Pearson correlation coefficient method: elevation, slope, aspect, curvature, rock/soil type, distance to river, distance to roads, and normalized vegetation index. The information model (IVM) was employed to evaluate the susceptibility and analyze the correlations between causative factors and disaster distribution. Through programming implementation, the analysis, transformation, management and drawing of the previous factor data are automatically processed, the IVM-RF (random forest) coupled model is improved, and the automatic cycle iteration comparison selection of the model is realized. The accuracy of the two susceptibility models is compared by ROC curve. Based on the evaluation results of the coupled model, the risk assessment was carried out. The Pearson type Ⅲ curve was used to estimate the rainfall in the study area under four different conditions of 10, 20, 50 and 100 years, and the risk zoning was carried out.

For the results of susceptibility zoning, the AUC value of the evaluation results of the information-random forest coupling model is 0.87, which is better than the evaluation results of IVM. For the results of risk zoning, the area of high and extremely high-risk areas have gradually increased from 10 to 100 years. The improved coupled model evaluation method not only simplifies the operation but also improves the accuracy.

According to the survey results, the coupled model does have better evaluation accuracy and prediction ability.

The vadose zone serves as a critical link between vegetation and groundwater, with its lithological structure being one of the main factors influencing groundwater ecological functions. However, the low-permeability interlayer within the vadose zone structure has a delayed effect on the infiltration flow from the surface and local water retention (perched water). Although the water volume in this zone is relatively small, it plays a significant role in supplying water for maintaining vegetation ecology in extremely arid areas. To explore how lithological structure affects soil water content distribution,

four soil columns were designed: A homogeneous soil column (O), a thin interbedded soil column (A), a single thick interbedded soil column (B), and a double interbedded soil column (C). Indoor drainage and infiltration experiments were conducted on these layered heterogeneous soil columns. Numerical simulations of variable saturation flow were performed based on the physical experiments.

The fine-grained soil interlayer structure causes water retention within the interlayer and at the upper and lower interfaces of the interlayer, forming a water accumulation zone. Compared with column O, the water release duration of columns A, B, and C increased by 290, 500, and 780 h, respectively, and the water holding capacity increased by 6.20, 7.90 and 7.83 cm, respectively. The numerical simulation results show that the modified van Genuchten model can better simulate the layered soil moisture profile.

The fine-grained soil interlayer has a significant retarding effect on the migration of water within the vadose zone, and water is mainly retained inside the interlayer and at its upper and lower interfaces. The increase in the thickness and number of interlayers leads to greater water retention within the interlayer and at the interlayer interfaces. The corresponding relative permeability equation is divided into three stages, which can effectively improve the simulation accuracy of the layered soil water content profile.

However, studies on the genesis of threshold-value elements and the related hydrochemical evolution processes are limited. Furthermore, some sampling points have exceeded the threshold values, directly affecting the development and utilization of mineral water, presenting an urgent issue that needs to be addressed.

This study focuses on the Huangshui River catchment as a target area, employing hydrogeochemical and modeling methods to uncover the hydrochemical characteristics and genesis of mineral water. Spring samples from the catchment were collected to gain insights into the hydrogeochemical processes within the groundwater system of the Huangshui River catchment.

Most groundwater samples in this study area meet the national drinking natural mineral water standards, with strontium concentrations exceeding 0.2 mg/L, and some samples are enriched with lithium and metasilicic acid. Hydrogeological results show that groundwater moving from the recharge area to the discharge area undergoes a transition in hydrochemical types, from HCO₃-Ca·Mg to SO₄-Na, which results from the dissolution of gypsum in groundwater. The relationships between Sr and major anions such as ${\mathrm{HCO}}^-_3 $, ${\mathrm{SO}}^{2-}_4 $, and Cl⁻ indicate that carbonates contribute minimally to the Sr concentration in groundwater. Instead, gypsum layers likely contain Sr-bearing minerals due to the ion exchange between Ca and Sr. These Sr-bearing minerals are responsible for the high Sr concentration in groundwater. The genesis of Li and Si in groundwater can be explained by the ancient salt lake sedimentary environment for lithium, and the dissolution of aluminosilicate minerals for metasilicic acid. Inverse modeling indicates that the groundwater primarily dissolves gypsum, rock salt, and illite, while the dissolution of azurite and lithium pyroxene contributes to the strontium and lithium concentrations in the northern catchment. The dissolution of gypsum and halite, combined with the dedolomitization process, leads to the high total dissolved solids (TDS) in the groundwater of the southern catchment.

The findings of this study provide a scientific basis for the exploration and preservation of mineral waters.

Concentrated recharge conditions exert critical controls on both hydrological regimes and water quality in karst underground rivers. Quantifying the differential impacts of recharge scenarios on these interlinked parameters remains a pressing research priority.

Based on hydrogeochemical surveys, this study implemented synchronous measurements of hydrological fluxes and solute dynamics at sinkhole recharge zone and the downstream conduit outlet within the Qinglongkou underground river system in western Hubei. This was done to explore the impacts of varying recharge conditions on the water quantity and quality of the underground river.

The results indicate that recharge intensity and soil moisture content directly control the flow generation and convergence processes within sinkhole , as well as the flow response of the karst underground river system. Rainfall events fail to activate conduit flow response that below a threshold. Concentrated recharge mobilization triggered notable solute enrichment, manifested as 2-3 fold increases in ionic concentrations (relative to background levels) at sinkholes. High-intensity rainfall would amplifield hydrochemical pertubations at the system oullet through the enhanced solute flusing. With TIN (total inorganic nitrogen) and phosphates accumulate at the sinkhole entrance following the heavy rainfall. Nitrogen speciation dynamics demonstrated stage-dependent behavior: ammonium (${\mathrm{N}}\text{-}{\mathrm{NH}}^+_4 $) preceded nitrate (${\mathrm{N}}\text{-}{\mathrm{NO}}^-_3 $) in the conduit flow sequence, while nitrate/TIN fluxes increased downstream whereas ammonium fluxes progressively attenuated-consistent with in-conduit nitrification processes.

These findings of this study provide a scientific basis for pollution prevention and control, as well as water environmental management of karst underground rivers.

In order to investigate the relationship between borehole imaging and flow velocity and direction tests in calculating the permeability coefficient of a single fracture, a new and more convenient method for calculating the permeability coefficient was proposed.

Taking the borehole ZW2 in the Lichuan coal mining area as an example, this study determines the equivalent permeability coefficient through the underground water flow velocity and direction tests, and the borehole imaging test. The results were then compared with the result from the pumping test.

The results show that the equivalent permeability coefficients obtained from the borehole imaging test and the velocity and direction tests are basically consistent with the permeability coefficient calculated by the pumping test, with errors of 40% and 9%, respectively. There is a linear correlation of permeability coefficients between the results from borehole imaging test and those from the velocity and direction tests, with the regression equation being Y=−0.23+0.82X. By correcting the permeability coefficients obtained from the borehole imaging test through the above linear relationship, a new method for calculating the permeability coefficient has been obtained, which is more convenient and accurate.

This method is relatively reliable and can directly calculate the permeability coefficients of single fractures, regional fractures, and the entire borehole at different scales. It has the advantages of short test periods, less work, lower cost, and wide applicability.

Excessive carbon dioxide (CO₂) emissions have led to global climate variability, resulting in a series of environmental challenges. As a critical technology for reducing CO₂ emissions, carbon capture, utilization, and storage (CCUS) plays a significant role in mitigating large-scale CO₂ emissions. The application of CO₂ storage in saline aquifers, particularly in offshore China, offers promising prospects with substantial technical and economic potential.

To address the uncertainties regarding favorable areas and CO₂ storage potential in saline aquifers of Ying-Qiong Basin, this study evaluates the geological suitability for CO₂ storage by calculating the weights of key components and the suitability score based on the basin's geological characteristics. Additionally, the CO₂ storage potential is assessed using effective CO₂ storage coefficients obtained through numerical simulation and various storage potential calculation methods.

The results indicate that the storage capacity determined by the EC method is lower than that obtained using the USDOE and CSLF methods. Since the CSLF method accounts for storage mechanisms such as geological structure storage, residual gas storage, and dissolution storage, its results are more reasonable. The CO₂ storage potential in saline aquifers of Ying-Qiong Basin and Qiongdongnan Basin is estimated to be 7.96×10¹⁰ and 4.40×10¹⁰ t, respectively. The total CO₂ storage potential in Ying-Qiong Basin's saline aquifers is 1.24×10¹¹ t, further confirming the significant potential for industrial-scale pilot and demonstration projects.

This provides a solid foundation for future CO₂ storage initiatives in saline aquifers of Ying-Qiong Basin.

This study aims to investigate the effects of cadmium on the mechanical and physical-chemical properties of loess.

A series of tests, including compression test, direct shear test, compaction test, permeability test, acidity and alkalinity test, and particle size analysis, were conducted on remolded loess samples with various Cd²⁺ concentrations. Changes in the microstructure of the Cd-contaminated loess were observed using scanning electron microscopy (SEM).

The results showed that the pH value of loess decreased obviously when the Cd²⁺ concentration exceeded 300 mg/kg. Permeability first increased and then decreased with the rising Cd²⁺ concentrations. Cadmium contamination had no significant effect on the particle size distribution of loess. As Cd²⁺ concentration increased, the compressibility of loess increased, while cohesion decreased. The angle of internal friction and shear strength initially increased and then decreased. The optimal moisture content decreased, while the maximum dry density increased. The porosity and proportion of medium pores increased under 30 mg/kg cadmium concentration but decreased under 3000 mg/kg, while the proportion of small pores increased under 3000 mg/kg cadmium concentration. The hydrolysis of cadmium nitrate in pore water, the chemisorption of cadmium onto loess particles, and the formation of a compressed double electric layer after cadmium addition were the main factors driving changes in the physical-chemical properties, mechanical properties, and microstructure of cadmium-contaminated loess.

The findings could provide a reference for evaluating the engineering properties and mitigating engineering disasters of cadmium-contaminated soils in loess areas.

In response to challenges such as strong reservoir heterogeneity, low signal-to-noise ratios in seismic data, insufficient prediction accuracy for poststack reservoirs, and difficulty in identifying fractures in ultradeep carbonate reservoirs in Shunbei, a new method is explored to increase the prediction accuracy for fractured reservoirs on the basis of five-dimensional seismic data.

To study the reservoir development characteristics of the Shunbei fault-controlled fracture-cave-type oil and gas reservoirs, a five-dimensional seismic anisotropic forward simulation was conducted, relationship between the seismic amplitude and fracture parameters were established, and the sensitive parameters for fracture prediction were optimized. On the basis, a Fourier series form of the directional elastic impedance equation was derived, fracture-type reservoir prediction was carried out, and the method was applied to the Shunbei Well X area.

The AVAZ seismic response characteristics of ultradeep carbonate rock fault-controlled reservoirs were clarified, and the fracture density was identified as a sensitive parameter for identifying fractured reservoirs. Additionally, using second-order Fourier coefficients to characterize fracture development density, a precise characterization of fracture-type reservoirs in the Shunbei Well X area was achieved with high prediction accuracy.

The application of five-dimensional seismic prediction technology based on amplitude attributes enhances the prediction of the fracture development density and direction by utilizing amplitude and orientation information from wide-azimuth seismic data. The established Fourier coefficient fracture density mapping relationship provides a quantitative prediction tool for fracture-controlled fracture-cave reservoirs and offers new ideas for fracture prediction and target evaluation in such reservoirs.

Three-dimensional (3D) geological modeling is a technology that comprehensively utilizes computer technology, spatial information, scientific visualization, mathematical statistics, and other cutting-edge technologies and methods to conduct 3D digital representation, characterization, and reconstruction of geological phenomena and processes. Its purpose is to provide a visualization platform that integrates scientific research, auxiliary design and decision support for geoscientists and geological workers to understand and utilize the essential meanings and laws hidden behind geological phenomena and processes more deeply.

Building 3D geological models of research areas based on field geological data has become a necessary task for geological research and surveys involving basic geological surveys, natural resource exploration and development, geological disaster prediction and evaluation, etc. This paper deeply discusses the research objects, data sources, spatial data models of 3D geological modeling, as well as three different perspectives for understanding 3D geological modeling methods, and comprehensively summarizes the latest progress of 3D geological modeling technology. It also provides practical cases of 3D geological modeling technology in the fields of mineral exploration, geological disaster warning, urban underground space planning, and oil and gas reservoir characterization.

Finally, based on the current research status, the future development trends of 3D geological modeling and related technologies are presented.

Artificial intelligence (AI) technology has become a hotspot and frontier direction in the exploration and development of mineral, oil, and gas fields. However, studies on its application in geothermal field development are limited. This paper first discusses the significant value of big data and AI in oil and gas field development, and then reviews the current applications of AI in geothermal field development.

Taking the Xianyang geothermal field in Shaanxi Province as a case study, a time series model for the temperature of geothermal water in a single well was constructed using a long short-term memory (LSTM) neural network under the predetermined production mode. Additionally, the random forest and XGBoost algorithms were used to predict the groundwater temperature of multiple geothermal wells.

The accuracy of the three models was above 95%, and their running speed was fast. The depth of the water intake section's top was found to be the primary influencing factor on geothermal water temperature in the area. The model also confirmed that WeiBei fault zones play an important role in heat storage.

The application of these models demonstrates the superiority of machine learning in addressing complex problems in geothermal field development. The reasonable application of AI can provide a more effective decision-making basis for the efficient development of geothermal fields, as well as for scientific cost reduction, quality improvement, and efficiency enhancement.