Marine ecological observation has become one of the essential approaches to supporting ocean exploration, ecological protection and restoration, disaster prevention and reduction, and early warning of ecological hazards. With the intensification of human activities and the accelerating impacts of global climate change, typical marine ecosystems are increasingly facing severe degradation and fragility. These threats include frequent red tides, eutrophication, and biodiversity loss in coastal waters, all of which impose significant economic and ecological costs. Against this backdrop, there is an urgent demand to establish advanced real-time, automated, and intelligent ecological observing systems. Such systems are expected to capture dynamic variations of marine environmental parameters and provide a scientific basis for sustainable marine management and the construction of ecological civilization.

This paper provides an overview of international progress in marine ecological observation technologies, focusing on nearshore, deep-sea, and seafloor monitoring systems. Developed marine countries have built integrated observation networks composed of buoys, coastal stations, underwater platforms, and satellite remote sensing, which together achieve long-term, continuous, and real-time monitoring of multiple environmental and ecological parameters. Typical examples include the United States Integrated Ocean Observing System (IOOS), the Ocean Observatories Initiative (OOI), Canada's NEPTUNE seafloor network, and Europe's EMSO project. These networks have demonstrated the capability to monitor not only hydrological and meteorological variables but also ecological indicators critical for predicting and preventing ecological disasters. By comparison, China's ocean ecological observation systems started relatively late and have mainly relied on coastal eco-buoys since the reform and opening-up period. Although more than 100 buoy-based monitoring stations have been deployed across major coastal provinces, these systems are still limited in scope, parameter diversity, and integration capacity. Current observation remains dominated by localized, single-point monitoring, with insufficient network connectivity and poor spatial resolution. Moreover, the existing systems are constrained by limited endurance, high maintenance costs, and weak data-sharing mechanisms, making it difficult to fully meet the requirements of ecological disaster early warning and ecosystem protection in the new era.

To overcome these limitations, this paper proposes that China's ecological observation should shift from simple buoy-based approaches toward the construction of collaborative, stereoscopic observation networks. Such networks should integrate multiple platforms: Shore-based towers, eco-buoys, underwater cabled observatories, shipborne systems, unmanned aerial vehicles, and satellite remote sensing: Forming a comprehensive "shore-sea-air-space" observation framework. With enhanced accuracy, extended parameters, and improved spatial and temporal coverage, these networks would enable dynamic, multi-dimensional monitoring of marine ecological processes. The establishment of such integrated networks is expected to play a crucial role in early warning of ecological disasters such as harmful algal blooms, coral bleaching, and ecosystem degradation. Furthermore, the accumulation of long-term, continuous datasets will provide essential support for assessing ecosystem health, guiding ecological restoration projects, and improving the resilience of coastal socio-economic systems. On a broader scale, advancing China's marine ecological observation capacity will also contribute to international collaboration in global ocean observing, strengthen data-sharing, and enhance China's role in addressing global marine environmental challenges. In summary, the paper highlights both the progress and the limitations of China's current ecological observation efforts and argues for a transformation toward advanced, stereoscopic, and multi-platform ecological observing systems. This transition is vital for improving marine ecological protection, supporting disaster prevention and mitigation, and achieving the long-term goal of sustainable ocean development under ecological civilization.

To improve the calculation efficiency of slope stabilities for multiple profiles, this study prop oses a method based on spatial slope stability coefficient calculations.

The two-dimensional residual thrust method is incorporated with spatial profiles, which forms a residual thrust method for spatial profiles.

The calculation process of the residual thrust method for spatial profiles is optimized by the automatic generation and management of profiles within a three-dimensional engineering geological mode of a slope. In order to achieve rapid and efficient calculation of slope stability coefficients, a method based on multi-threaded parallel computation is introduced. Combining this approach with the residual thrust method for spatial profiles allows for more accurate and efficient computation of stability coefficients for multiple spatial profiles.

Using an open-pit mine in Xilinhot, Inner Mongolia, as a case study, we establish a three-dimensional slope engineering geological model for the internal dump site slope. On this basis, seven spatial profiles are automatically generated, and stability coefficients are calculated using multi-threaded parallel computation. Finally, the results are presented visually.

The research findings indicate that adopting multi-threaded parallel computation for calculating slope stability coefficients for multiple profiles can fully utilize computing resources and significantly improve computational efficiency. Furthermore, application in engineering projects confirms the feasibility and applicability of the proposed method.

A high-resolution, continuous chronostratigraphic framework was established using the astronomical cycles, and the paleoclimatic characteristic was analyzed for the Oligocene Lingshui Formation of the Beijiao Sag.

The cyclostratigraphy characteristics and the paleoclimatic evolution were determined by time series and multiple paleontological proxies analyses, respectively, in the Well A of the Beijiao Sag.

Cycles of 405 ka long eccentricity, 100 ka short eccentricity, 42.7 ka and 43.2 ka obliquity, and 20.5 ka precession were identified in the Lingshui Formation of the Beijiao Sag. Considering the time anchor of 23.03 at the top of Oligocene, the astronomical tuning revealed a "floating" astronomical chronology scale of 5.59 Ma. Within the high-precision absolute astronomical timeframe of the Lingshui Formation (23.03−28.62 Ma), the bottom boundary ages of Ling I, Ling II, and Ling III members can be determined as 23.97 Ma, 25.43 Ma, and 28.62 Ma, respectively. These ages correspond to the average sedimentation rates of 18.4 cm/ka, 8.6 cm/ka, and 12.8 cm/ka, respectively. The palaeoclimatic indicators, including the foraminifera, organic carbon, organic detrital fractions, and carbon and oxygen isotopes, suggest an overall warm-cool-warm trend during the deposition of Lingshui Formation. The comparison of palaeoclimate evolution with astronomical rotation suggested that the climate evolution during this period was mainly controlled by astronomical orbital forces such as eccentricity and age difference.

Astronomical cyclostratigraphic study on the Lingshui Formation of the Beijiao Sag explores the control of astronomical orbital parameters on paleoclimate and establishes a high-resolution and continuous chronostratigraphic framework. This method provides a refined chronological framework for predicting high-quality reservoir intervals in oil and gas exploration, promoting the development of oil and gas exploration in the Beijiao Sag.

Petroleum breakthroughs in the strike-slip fault zones of the northeastern Shunbei area in the last decades reveled the spatial variation in petroleum accumulation types and phase patterns, including the oil accumulation on the north, condensate gas accumulation on the south, and dry gas accumulation on the east. Therefore, to further advance ultra-deep petroleum exploration, it is crucial to reveal the genesis mechanism, source, and thermal maturation of the natural gas from the perspective of overall petroleum distribution.

This study systematically collected gas samples from various fault zones in the Shunbei area in order to analyze the geochemical characteristics of natural gas and reveal its generation mechanism or thermal evolution process.

The results indicate that the natural gas in the Shunbei area was minimally affected by TSR even though some parts of the fault zones showed strong modification of thermal-chemical sulfate reduction (TSR). The natural gases in the No. 1 fault zone and in the northern and middle sections of the No. 5 fault zone are primarily crude oil-associated gases generated by primary kerogen cracking. In contrast, the natural gases in the southern section of the No. 5 and No. 4 fault zones were mainly the mixture of early kerogen cracking gas (oil-associated gas) and late crude oil cracking gas. The natural gas in the Shunbei No. 12 fault zone originated from deeper, high-temperature crude oil cracking gas, which occurred at the wet gas stage. The natural gases in the study area predominantly came from the source rocks of the Lower Cambrian Yurtus Formation, and the parent material of these gases is characterized by benthic algae or a mixture of benthic and planktonic algae. Finally, a regression equation for thermal maturity calculation based on the carbon isotope of methane was established for the hydrocarbon generation process in the source rocks of the Yurtus Formation.

The research findings provide important insights into the origin, source, and thermal maturity of ultra-deep gas, offering valuable references for future studies on hydrocarbon generation in the Shunbei area.

Current research on the Jurassic Kizilnur Formation coal seams in the Kuqa Depression mainly focuses on shallow sections, with limited study of deep coal seams.

To address unknown coal-rock characteristics, reservoir properties, and gas content in the Jurassic Kizilnur Formation coal seams, the geometric distribution characteristics, the characteristics of coal rock and coal quality, reservoir properties, adsorption properties, and gas content of the coal seam in this block were studied based on the following methods, such as drilling data, seismic data processing, wellbore analysis, sampling observation, gas measurement, pore permeability, and isothermal adsorption experiments.

The deep coal seams in the research area are predominantly composed of primary structures, with vitrinite as the major organic component (average 62.2%), indicating type Ⅲ organic matter. The coal is of medium rank, generally characterized by medium-to-high volatile matter, ultra-low sulfur, and low to very low ash content. The average gas porosity is 7.10%, and the average permeability is 0.685×10⁻³ μm². Furthermore, methane adsorption capacity is strongly influenced by macrinite reflectance, water content, and ash yield. In the Kuqa Depression, deep coal seams occur at burial depths of 2 000 –5 000 m, are mainly distributed in the Northern Structural Zone, cover about 2 800 km², with a maximum single-layer thickness of 22 m. The average gas content of the deep coal seam measured is 11.77 m³/t, indicating substantial resource potential.

Compared with shallow coal seams, the deep coal seams of the Kezilnur Formation in the study area are more strongly affected by burial depth, exhibit high maturation, and have achieved large-scale gas production, underscoring their exploration potential. Water saturation emerges as a critical factor controlling gas content in these seams. Notably, the Dibei gentle-slope platform in the Kuqa Depression offers particular advantages for CBM extraction due to favorable hydrological and geological attributes.

Tectonic fractures play a significant role in enhancing the physical properties and hydrocarbon productivity of deep volcanic buried-hill reservoirs. Due to their strong heterogeneity, precise characterization of fracture density across different parts of the fault zone is required. In practical production, the high cost of core acquisition and imaging logging data motivates the use of a comprehensive fracture index (CFI) calculated from conventional logging curves to delineate the internal structure of fault zones and quantitatively identify fracture density, providing a basis for exploring fractured volcanic reservoirs.

A CFI model was constructed for Mesozoic volcanic rocks in the Bonan area of the Bohai Bay Basin using seven logging parameters: Acoustic travel time (AC), neutron porosity (CN), bulk density (DEN), caliper (CAL), deep lateral resistivity (RD), shallow lateral resistivity (RS), and micro-lateral resistivity (RMLL). The cumulative CFI curve slope was used to define the boundaries of fracture-dense zones, partitioning the fault zone into the fault core, damage zone, and host rock. The damage zone exhibits the highest fracture density, followed by the host rock, while the fault core is nearly fracture-free.

In the Mesozoic volcanic rocks of the study area, the seven conventional logging curves show distinct responses in fracture-developed zones: AC, CN, and CAL increase, whereas DEN, RD, RS, and RMLL decrease. The CFI curve shows a pronounced rise in fracture-rich intervals. Comparison with imaging logs and core data confirms that high CFI values correlate with fracture zones. By integrating seismic interpretation to identify the fault core, the distribution of the damage zone and host rock can be delineated, enabling effective fracture prediction in Mesozoic volcanic rocks in the Bonan area.

The CFI model, derived from logging curves, can effectively quantify the intensity of fracture development in volcanic rocks, locate the downhole spatial distribution of fracture-dense zones, and enable the reliable identification of internal-zone structures via cumulative CFI curve analysis.

To reduce the risk of landslide disasters and further ensure regional sustainable development, conducting research effectively on landslide monitoring and prediction is of great practical significance. This paper aims to continuously improve the prevention and control level of landslide disasters by studying the key technologies and methods in landslide monitoring and prediction, and will analyze the efficiency and accuracy of various algorithms in scenarios of landslide monitoring and prediction.

In terms of feature extraction technology, the performance of three image feature matching algorithms, namely namely scale-invariant feature transform (SIFT), speeded up robust features (SURF) and assessment of scale-invariant features transform (ASIFT), were compared and analyzed. Comparative results demonstrate that ASIFT has significant advantages in the number of matches, precision rate and recall rate, and is especially suitable for complex environmental scenarios with high-accuracy requirements. In terms of optical flow analysis technology, the application effects based on the Lucas-Kanade sparse optical flow method and the Horn-Schunck dense optical flow method were discussed. Among them, the Lucas-Kanade sparse optical flow method has high computational efficiency and is suitable for real-time application scenarios, but there is a risk of missing important motion information. The Horn-Schunck dense optical flow method can provide comprehensive optical flow field information and is suitable for complex environmental scenarios. However, it has the drawback of high computational complexity and thus is difficult to be used in real-time processing. In terms of landslide susceptibility prediction, the advantages and disadvantages of the application of classic machine learning methods such as support vector machine (SVM), decision tree (DT), and random forest (RF) in landslide prediction are introduced in detail. The model performance based on particle swarm optimization-support vector machine (PSO-SVM) is mainly studied. This model optimizes hyperparameters, the classification accuracy, generalization ability and prediction accuracy of the model have been significantly improved. Furthermore, by introducing the Faster R-CNN model and leveraging its advanced convolutional neural network architecture, this paper realizes the automatic identification and classification of landslide events in complex scenarios, further enhancing the efficiency and accuracy of landslide monitoring and early warning.

The research shows that the accuracy rate of local feature extraction by ASIFT is 0.84, the tracking error of the Lucas-Kanade sparse optical flow method is 0.12, the root mean square error of the PSO-SVM model is 0.52, and the confidence level of the Faster R-CNN model in the automatic recognition and classification of landslide images can reach 0.98. The comprehensive performance is significantly improved compared with other algorithms in this paper.

In summary, by introducing artificial intelligence algorithms and integrating multi-disciplinary technical means, this paper has comprehensively enhanced the efficiency and accuracy of landslide monitoring and prediction technology. The research results provide more powerful technical support for the prevention and control of landslide geological disasters.

The Fuman oilfield has significant potential for oil and gas exploration, and is a key area for increased oil reserves and production in the Tarim oilfield. Analyzing the source, thermal maturity, and charging process of crude oils in this area is essential for understanding the hydrocarbon accumulation patterns, enrichment laws, and guiding future exploration activities.

Based on systematic organic geochemical analysis of 15 crude oil samples and fluid inclusion samples from three wells, as well as the orientation segmentation and active phases of the strike-slip fault, this study examines the geochemical characteristics of crude oils, hydrocarbon charging processes, and their main controlling factors in the F_I17 strike-slip fault zone.

The results show that the crude oil in this fault zone is derived from the Lower Cambrian Yurtus source rocks. The equivalent vitrinite reflectance value of the crude oil, calculated from aromatic parameters, ranges from 0.80% to 1.20%. The crude oil has undergone relatively weak thermal chemical sulfate reduction (TSR), gas stripping, and oil cracking. The fault zone and its periphery have experienced three stages of oil charging with different maturities: Late Caledonian, Late Hercynian, and Himalayan periods, and the gas charging occurred during the Himalayan period. However, there are differences in oil maturity within the same period between the northern and southern segments. The northern and middle segments are mainly dominated by oil contributions from the second stage (blue-green fluorescence) and third stage (bright-blue fluorescence), however, the southern segment is predominantly charged by the second-stage oil with bright-blue fluorescence and the Himalayan-period gas invasion altering pro-existing oil. The F_I17 strike-slip fault zone exhibits a north-to-south increasing gradient in the oil thermal maturity, gas stripping intensity, oil cracking degree and contribution of late-stage hydrocarbons.

This spatial variation is governed by fault activity intensity that intensifies southward, which is stronger in the south and weaker in the north. This study suggests the likely presence of deeper, late-stage high maturity hydrocarbons in the northern and middle sections of the fault zone, and the current exploration depth has not yet reached the lower limit of liquid hydrocarbon occurrence. Therefore, deeper reservoirs still have significant potential for oil and gas exploration.

Previous thermal structure analyses in the Songliao Basin have predominantly focused on the sedimentary scale investigations within the north-south zone. The lack of a comprehensive basin-wide thermal structure analysis at the lithospheric scale has hindered the genetic interpretation of its geodynamic setting.

Utilizing published datasets of surface heat flow, geothermal gradient, and thermophysical properties, this study enhances the existing framework by incorporating new thermophysical measurements from the Yaojia Formation, Qingshankou Formation and Quantou Formation. Supplementary geothermal filed datasets were integrated to establish a holistic characterization of the basin's geothermal regime. This multi-scale approach enables systematic analysis of the contemporary lithospheric thermal architecture.

The results reveal that the geothermal temperature gradient in the Songliao Basin ranges from 21.10 to 63.45°C/km, with an average of 41.41±7.97°C/km, significantly exceeding the global average of 30°C/km. The distribution of surface heat flow values ranges from 30.38 to 106.58 mW/m², with an average of 71.85±12.87 mW/m², surpassing the global average of 60 mW/m², confirming the basin as a typical "hot" basin. Under the influence of Pacific plate subduction, delamination and thermal erosion, the lithosperic thickness have thinned to 58.59 km. Radiogenic heat production in the thinned crust contributes 16.40 mW/m² (22.83% of total surface heat flow), while mantle-derived heat flow from upwelling melts triggered by stagnant slab dehydration accounts for 55.45 mW/m² (77.17% of total)

Controlled by lithospheric thinning and mantle upwelling, the Songliao Basin exhibits characteristic of "hot" basin attributues with a "hot mantle and cold crust" lithospheric thermal structure.

The development of karst reservoirs in the Maokou Formation of the Lower Permian in southern Sichuan Province is critical for conventional oil and gas exploration in this region. The development level of supergene karst reservoirs is directly controlled by the rich and diverse karst microgeomorphology, leading to strong lateral heterogeneity within these reservoirs.

In this study, 3D seismic data, combined with strata thickness, gradient structure tensor attributes, and geological body carving techniques, were employed to characterize the microgeomorphic features of the Dongwu karst in the Yunjin area. Moreover, favourable zones for surface karst reservoirs were predicted through model forward modeling and amplitude attributes.

The results suggested that significant differences in karst microgeomorphology existed during the Dongwu period in the Yunjin area, where a series of karst caves developed. These caves exhibit a seismic feature of a "pull-down" in the seismic event axis at the top boundary of the Maokou Formation. ② The distribution pattern of karst collapse bodies in the Yunjin syncline area was effectively characterized using gradient structure tensor attributes combined with geological body carving technology. The karst collapse bodies exhibit three distinct distribution patterns: Isolated, linear, or contiguous distributions. ③ The seismic amplitude on both sides of the karst collapse bodies is weakened, indicating strong karstification and the development of karst caves, which are favorable zones for reservoir development.

This research provides guidance for the subsequent prediction and exploration of reservoirs of the Maokou Formation.

The traditional temperature-pressure field analysis method relies heavily on the interpolation of existing borehole data, which fails to accurately characterize the coupled seepage-heat transfer processes in geothermal systems. This limitation hinder comprehensive understanding of geothermal resources formation mechanisms.

To address these issues, we constructed a three-dimensional geological model of the Zhangye Basin by integrating multisource datasets (borehole information, geophysical data, and digital elevation model). Our integrated approach enhanced the resolution of inter-well stratigraphic correlation by 50–300 m compared to conventional methods. Numerical simulations of coupled seepage-thermal process revealed that multi-physical-field coupling analysis (incorporating both temperature and pressure fields) outperforms traditional key-node spatial interpolation approach in reliability. The results show hydraulic head gradient decreased from the southeastern to the northwestern discharge area, and northeastward heat depletion patterns are due to reservoir shallowing and caprock thinning. The maximum temperatures of 78℃ occurs at the basin center with peripheral cooling effects. A three-dimensional geothermal conceptual model was subsequently developed, synthesizing structural, hydrogeological, and thermal geological constraints.

Coupling this model with heat-flux simulations demonstrated, our study demonstrate that it could provide more realiable interpretation of the northwestward groundwater migration and the Rhombic-lobate spatial distribution of the geothermal anomalies.These findings provide a theoretical framework for targeting high-enthalpy geothermal reservoirs and optimizing sustainable exploitation strategies.

Currently, exploration and development of shale hydrocarbon primarily focus on mid-shallow marine and lacustrine shales. However, research on the sedimentary characteristics of deep lacustrine shales in rift basins is scarce, so their exploration potential is unclear. Consequently, this study holds significant practical implications and can provide valuable insights into the exploration and development of deep lacustrine shales in the rift basins. A typical deep shale series developed in the distal part of the fan front and the deep lake area of the Third Member of the Shahejie Formation in the Banqiao Sag, which is a continental rift basin. This study aims to identify the sedimentary characteristics of the deep lacustrine shale in the Third Member of the Shahejie Formation in the Banqiao Sag, to demarcate the vertical sweet spots of shale oil and gas, and to comprehensively evaluate the exploration potential of the deep lacustrine shale.

Based on data from core analysis, well logging, and various analytical tests, by employing techniques such as geological statistics, sedimentary facies and organic geochemical analysis, rock thin section observation, X-ray diffraction of whole-rock minerals, micro-CT scanning, and geophysical prediction, the macroscopic sedimentary features, rock fabric types, bedding structures, as well as microscopic structures and compositional characteristics of the shale were analyzed to explore its material basis for hydrocarbon generation and the conditions for hydrocarbon formation.

Macroscopically, the shale series of the Third Member of the Shahejie Formation can be classified into three types: mixed sedimentation type, intercalated type, and interbedded type. The mixed sedimentation type and intercalated type have a wide distribution range. The rocks mainly consist of black and dark gray mudstones, which are the dominant rock fabric types. Microscopically, extremely thin-laminated and thin-laminated mud shales exhibit relatively high organic carbon contents and are the dominant lamination types. The analysis of diagenetic evolution indicates that below a depth of 3 350 m, there are zones where interlayer water is rapidly expelled and zones where interlayer water is expelled rapidly along with organic matter. The resulting abnormal high pressure is conducive to the preservation of microscopic pores.

Comprehensive research shows that the main part of the shale series in the Third Member of the Shahejie Formation in the Banqiao Sag has reached the mature to highly mature stage. It possesses favorable conditions for the enrichment and accumulation of oil and gas on a large scale. Moreover, it is indicated that the C2 and C6 sweet spots are the main zones of oil and gas enrichment, providing theoretical support for the exploration and evaluation of shale oil and gas. The impact of tectonic activities on the generation and accumulation of shale oil and gas has not been adequately considered. Research on shale formations is still in its early stages, and numerous issues remain that require in-depth investigation. It is essential not only to elucidate the material basis for the occurrence of shale oil and gas but also to identify the key factors influencing their production. Therefore, future efforts should focus on achieving technical breakthroughs in the field of integrated geological and engineering approaches.

To address this challenge, it is imperative to strengthen the research and geological exploration of new types of niobium deposits.

This study focuses on the clay rocks in the lower part of the Upper Permian Longtan Formation (P₃l) in Xingwen area of southern Sichuan. Based on the analysis of Nb contents in the collected samples, we combine various analytical techniques such as X-ray powder diffraction (XRD), scanning electron microscopy with energy dispersive spectrometer (SEM-EDS), and electron probe micro-analyzer (EPMA) to conduct mineral identification and quantitative analysis on Nb-enriched samples.

The results show that the content of Nb₂O₅ in the clay rocks ranges from 41×10⁻⁶ to 437×10⁻⁶, with an average of 187.2×10⁻⁶, reaching the lowest industrial indicator for weathering crust-type deposits. The enrichment of elements like Li, Ga, and others is also significant, making the clay layer rich in multiple critical metals and possessing considerable ore-forming potential. XRD analysis reveals a substantial presence of anatase in the Nb-rich clay rock. EPMA analysis indicates that the content of Nb₂O₅ in anatase ranges from 0.09% to 3.40%, with an average of 1.17%. Based on the Nb content in anatase, SEM-EDS scanning, and the Nb₂O₅ content of whole-rock samples, we conclude that Nb primarily exists in anatase as an isomorphous substitution, and some are adsorbed by clay minerals. Nb is predominantly inherited from the weathering products of minerals such as sphene in the Emeishan basalts, and the weathering degree has a significant impact on the enrichment and mineralization of Nb, with characteristic of weathering-sedimentary deposit.

The research results provide a scientific basis for the geological prospecting, resource evaluation, and comprehensive development and utilization of niobium resources.

The Qikou Sag, a significant hydrocarbon-bearing sub-basin within the Bohai Bay Basin of eastern China, has recently witnessed a critical exploration breakthrough. Well HT1, drilled in the main trough, encountered a sandstone reservoir within the Third Member of the Dongying Formation (Ed₃) and achieved commercial oil flow. However, the precise provenance and spatial distribution of this Ed₃ sandstone remain enigmatic. Identifying the sediment source is fundamental to constructing a reliable "source-to-sink" system, which is crucial for predicting the distribution of high-quality reservoirs. This study aims to definitively determine the provenance of the Ed₃ sandstone through detrital zircon U-Pb geochronology and establish a robust sedimentary model to guide exploration.

To address the provenance question, this study employed laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb dating on detrital zircons extracted from the Ed₃ sandstone. Zircon is an ideal mineral for provenance analysis due to its high physical and chemical stability, allowing it to survive multiple cycles of erosion and transport while preserving its primary crystallization age. Thus, the age spectrum of detrital zircons in a sedimentary rock serves as a unique fingerprint that can be compared to the age signatures of potential source areas, enabling a direct link between the sediment and its origin.

The U-Pb dating results from the Ed₃ sandstone revealed a characteristic age distribution pattern. The detrital zircon ages cluster into four primary intervals: 2600−2300 Ma (Neoarchean to Paleoproterozoic), 1680−2000 Ma (Paleoproterozoic), 300−240 Ma (Permian), and a remarkably dominant peak between 160−100 Ma (Jurassic to Cretaceous). The overwhelming abundance of zircons in the 160−100 Ma range immediately pointed towards a significant contribution from a source region with intense Mesozoic magmatic activity. The zircon age signature of the Cangxian uplift was examined. Its age spectrum is characterized by a strong peak at 300−240 Ma and a relative lack of Mesozoic zircons, presenting a clear mismatch with the Ed₃ sandstone signature and effectively ruling it out as the primary source. In contrast, the Yanshan orogenic belt to the north is a complex tectonic zone with a prolonged magmatic history spanning from the Archean to the Mesozoic. Critically, it is renowned for widespread Jurassic-Cretaceous (Yanshanian) magmatism, with a pronounced age peak precisely between 160 and 100 Ma. The striking similarity between the Ed₃ zircon age pattern and the magmatic record of the Yanshan belt provides compelling evidence that the latter served as the principal provenance for the sandstone. Previous studies indicate that the Yanshan orogenic belt experienced significant Cenozoic uplift, coeval with the deposition of the Ed₃, creating a well-defined mountain-basin system. Several major paleo-rivers, such as the Paleo-Yongding River, Paleo-Chaobai River, and Paleo-Luan River, are interpreted to have acted as efficient sediment conduits. These rivers eroded the Mesozoic granitic rocks of the Yanshan belt and transported the detritus southward over long distances into the Qikou Sag.

This study successfully resolves the provenance of the Ed₃ sandstone in the main trough of the Qikou Sag. Detrital zircon U-Pb geochronology unequivocally identifies the northern Yanshan orogenic belt as the primary source, excluding the nearby Cangxian uplift. The construction of the "remote source, channelized transport, deep-trough deposition" model has profound implications for exploration. It validates the existence of high-quality sandstone reservoirs in the deep troughs formed by long-distance transport systems. Consequently, future exploration efforts should prioritize mapping the paleo-drainage pathways that funneled sediments from the Yanshan belt into the main trough of the Qikou Sag. This model significantly reduces exploration risk in the deep plays of the depression and provides a valuable analog for searching for similar subtle reservoirs in other continental rift basins worldwide.

In the Junggar Basin, the exploration targets are deeply buried beneath the earth surface, posing significant challenges for seismic exploration. Specifically, this result in severe high-frequency absorption and attenuation of seismic wave energy. The recorded seismic data are characterized by a limited bandwidth with low dominant frequency, which significantly compromises the accuracy of the sandstone-shale thin interbed identification. Thus, the poor quality of the seismic data makes the reservoir distribution and potential hydrocarbon prediction tasks extremely challenging. Deconvolution is a key technique to improve the seismic data resolution. It aims to reverse the effects of wavelet convolution in the recorded seismic data, and can be performed in either the time domain or the frequency domain. Frequency domain deconvolution usually uses the estimation of seismic spectrum to construct a spectral-broadening operator, thereby expanding the frequency band and increasing the dominant frequency of the seismic data. We develop a frequency-domain deconvolution method to enhance the vertical seismic resolution. The key to this method lies in the use of an optimized target spectrum, and the final goal is to expand the seismic bandwidth effectively.

We propose a generalized cosine broadband spectrum and incorporate it into the spectral inversion. Based on the relationship between the expected spectrum and diagonal matrix of the seismic spectrum, a spectral-broadening forward model is established. Subsequently, a shaping regularization inversion method is used to invert for the spectral-broadening operator. Ultimately, by applying the obtained spectral-broadening operator to the seismic data, the vertical seismic resolution can be enhanced. This is beneficial for more accurate geological interpretation and hydrocarbon exploration.

We use a theoretical model and field seismic data in the Junggar Basin to validate of the proposed method. The theoretical model has verified the effectiveness of the proposed method using the generalized cosine broadband spectrum. Subsequently, we apply the method to real seismic data from the Junggar Basin, where an optimized generalized cosine broadband spectrum is constructed based on the original seismic spectrum. The real seismic data processing results show that the frequency bandwidth of the seismic data has been effectively increased, leading to improved resolution of thin interbeds. The theoretical and field data results confirm the robustness and practical applicability of the proposed method.

The generalized cosine broadband spectrum has a wide frequency band range, and can be flexibly designed. Additionally, the corresponding wavelet exhibits low side-lobe amplitude and narrow side-lobe width, which minimizes interference from reflected waves. The proposed spectral inversion using the generalized cosine broadband spectrum can be used to improve the seismic resolution and provides reliable seismic data for unconventional hydrocarbon exploration.

The complex structure of river and lake-groundwater interaction zone governs the migration and transformation and the fate of nutrients. Investigating the spatial-temporal distribution characteristic and controlling factors of nitrogen in groundwater holds significant implications for water quality and ecosystem protection.

This study focus on the river-lake-groundwater interaction zone along the middle reaches of the Yangtze River. Groundwater samples were collected from two confined aquifer profile and one phreatic aquifer profile during both monsoon season and non-monsoon season.Hydrogeochemical analysis was conducted, and the controlling factors of nitrogen enrichment were identified using random forest regression.

The results indicate that the main form of nitrogen in groundwater is ammonium (NH₄-N). The content of NH₄-N in confined groundwater during monsoon season (0.37-4.96 mg/L, average 2.07 mg/L) was significantly higher than that in the pore phreatic water (0-0.096 mg/L, average 0.012 mg/L).Low concentration of Cl⁻ / SO₄²⁻ and high concentration of CO₂ / HCO₃⁻ indicate that NH₄-N enrichment is closely related to the mineralization of nitrogen-bearing organic matter under natural condition. In contrast, in pore phreatic groundwater during the non-monsoon season, the NH₄-N concentration (average 1.25 mg/L) was significantly higher than during monsoon season(average 0.032 mg/L), displaying prominent seasonal variation. The concentration of Fe / Mn was also relatively high in this aquifer during the non-monsoon season. Combined with water-level fluctuation data, the pore phreatic water is significantly influenced by human activities. Following NH₄-N enrichment within the aquifer, feammox can occur.

This study enhances understanding of the occurrence patterns of nitrogen within river-lake-groundwater interaction zone and provides a theoretical basis for studying biogeochemical processes associated with the nitrogen cycle.

There are a large number of high and steep slopes in mountainous areas in my country. Due to their concealment and danger, it is currently difficult to obtain data that can be used to extract and analyze geometric parameters and structural plane information of dangerous rock masses on high and steep slopes using a single non-contact measurement. For the refined investigation of dangerous rock masses, the characteristic parameter information of structural planes is the top priority.

Therefore, this paper fuses the point cloud data obtained from airborne lidar, ground lidar and UAV oblique photogrammetry with multi-source data, complements the advantages of the multi-source data, and uses the fused point cloud to analyze dangerous rocks on high and steep slopes. Parameters such as scale boundary, trailing edge characteristics and occurrence information are used to extract information.

The results show that the multi-source data fusion method used in this article effectively complements the advantages of various data. The fused point cloud is used to extract the scale boundary, trailing edge information and structural plane characteristic parameter information of dangerous rocks on high and steep slopes. The data extraction value All are within ±5°, meeting the requirements of the survey specifications.

This investigation method and information extraction method provide a new idea for detailed investigation of dangerous rock masses in vegetation-covered areas.

To identify the reservoir characteristics and influencing factors of Benxi Formation bauxite in the Linxing area,

the paper carried out XRD, cast sheet imaging, SEM-EDS, mercury intrusion porosimetry, nitrogen and carbon dioxide adsorption, and routine porosity measurements, coupled with seismic logging data, to characterize the mineral composition, pore structure, and physical properties of the bauxite reservoir and to discuss the controls on its development.

The results show that the aluminum-bearing minerals in Benxi Formation bauxite in the Linxing area are dominated by dispore. Pore types are primarily intra-granular, intergranular, matrix, and microcrack pores, with occasional organic pores. Pore volume is mainly contributed by mesopores and macropores, with pore-size peaks mainly at 30−70, 80−130, 4000−13000 nm. The overall reservoir physical properties are modest, with an average porosity of 3.28% and an average permeability of 1.398×10⁻³ μm². However, the lower part of the section, which has a higher diaspore content, exhibits relatively better properties. Finally, the development of the Linxing bauxite reservoir is controlled by palaeo-geomorphology, palaeo-sedimentary environment, and diagenesis. Specifically, accumulation and distribution of bauxite are controlled by the paleogeomorphology of depressions and troughs and by enclosed to semi-enclosed intermittent swamps and lagoons. Diagenesis determines the reservoir-space types and the resulting physical-property conditions within the sedimentary context.

The research results can provide theoretical guidance for the bauxite gas exploration.

A groundwater flow and solute transport model incorporating fault permeability was developed using GMS software.

The model simulated the impact of characteristic landfill pollutant seepage on the groundwater environment and a water delivery tunnel under various conditions, considering enhanced fault permeability.

The simulation results show that: Under normal operating conditions, due to the anti-seepage measures at the bottom of the plant, the polluant diffusion range is largely confiend within the plant site, and the maximum pollutants concentration at the center iremains below 0.5 mg/L. Under abnormal conditions (leakage scenarios), pollutants from leakage source No. 1, No. 2 and No. 3 reached the water delivery tunnel location at 800 days, 4015 days and 1095 days, respectively. The vertical diffusion range of pollutants progressively increased across the three leakage scenarios, whereas difference in the horizontal(area) diffusion range were minimal. Enhanced permeability of the F4 fault poses a greater environmental risk to pollutant migration in leakage source scenarios No. 1 and No. 3. In leakage source scenario No. 2, however, the enhanced permeability of the F3 fault does not significantly increase environmental risk levels in the tunnel area. To safeguard the local soil and water environment, anti-seepage reinforcement of potentially affected tunnel areas is necessary.

The findings of this research provide scientific support for groundwater pollution prevention and risk assessment in the study area.

Geophysical methods can effectively monitor the dynamics of water flow and material transport in 4D hydrogeological processes, and its imaging accuracy is often closely related to the monitoring scheme. Taking the commonly used electrical resistivity tomography (ERT) as an example, obtaining good imaging accuracy often requires a large number of electrode arrays, leading to a long data acquisition time and inability to respond in a timely manner to 4D hydrogeological dynamics. Previous optimization studies of ERT monitoring schemes have mainly focused on surface ERT, whereas cross-hole ERT (CHERT) has received far less attention.

Due to the advantages of CHERT in high-precision characterization, this study proposes using Bayesian experimental design to optimize CHERT monitoring scheme. Through laboratory static and dynamic tests and a field application, data acquisition time and imaging accuracy between the optimized and traditional electrode configurations to evaluate the effectiveness of the Bayesian-based optimization.

Laboratory tests demonstrate that the optimized monitoring scheme can reduce acquisition time by approximately 75%, and the inversion results more accurately delineate the evolving resistivity anomaly zones, thereby mitigating the lag effect observed in traditional schemes. The field application shows that the optimized scheme can reduce monitoring time by approximately 95%.

The optimization of CHERT electrode configurations based on Bayesian experimental design provides a technical basis for efficient monitoring of 4D hydrogeological processes.

Dry rock, a widely distributed and abundant geothermal resource, is of paramount importance in the reduction of fossil energy consumption, alleviating environmental pollution, and ensuring energy security. Enhanced geothermal systems are currently the main method for developing hot dry rock resources and are generally implemented through several methods, such as engineering site selection, geothermal drilling, thermal reservoir stimulation, flow testing, and power generation engineering. Among these, flow tests are a crucial link in undertaking thermal reservoir stimulation and power generation engineering and are used to form injection and production well groups, evaluate cycle circuits, expand heat exchange capacity, and lay the foundation for ultimately achieving power generation goals safely and stably. The implementation process of flow tests is long-term and complex, which can easily lead to problems such as insufficient connectivity, strong microseismic effects, liquid leakage, scaling of the circulating liquid, and insufficient equipment reliability. Therefore, flow tests at hot dry rock development sites internationally are often intertwined with drilling and reservoir stimulation and accompanied by scheme adjustments to gradually achieve the power generation goal.

This article briefly summarizes the flow test experiences and exploration directions of typical hot dry rock development EGS at home and abroad, elaborates on the influence of various factors on flow tests, and proposes development suggestions based on the actual situation at the Qinghai Gonghe site. In the past, improving the effectiveness of flow tests was achieved through methods such as adjusting the development layer and well groups, long-term circulation, hydraulic fracturing, and chemical stimulation. However, current technicians have focused on accurately obtaining engineering parameters and improving the design of well groups and reservoir stimulation processes.

In summary, the formulation of a flow test plan needs to fully consider geological factors and adapt to local conditions. Moreover, key technologies in flow tests, such as reservoir evaluation, reservoir stimulation, and engineering implementation, are worthy of in-depth research. The progress of these key technologies requires the establishment of numerical models with greater accuracy, improvements in the accuracy and stability of various monitoring techniques, the application of more diverse hydraulic fracturing and chemical stimulation processes, and the establishment of a more comprehensive risk prevention and control system for induced earthquakes. In addition, the application of new technologies is also a possible breakthrough. Supercritical carbon dioxide and liquid nitrogen fracturing technologies have advantages in thermal reservoir fracturing and energy enhancement in hot dry rock stimulation. Explosive fracturing technology has a certain effect on increasing the complexity of fractures near wellbores and enhancing the injection capacity of well groups. Finally, with the goal of experimental power generation and focusing on key issues in multi-well group flow tests, improving the construction process of flow tests is also an effective means to improve efficiency and reduce costs. With increasingly mature development technology, hot dry rock geothermal resources will become an important part of China's energy structure, playing a significant role in economic development and environmental protection.

This study investigates the dissolution and mechanical degradation of carbonate rocks under the influence of acidic leachate.

Limestone samples are subjected to acidic leachate under varying flow conditions and durations. The dissolution effects are evaluated through comprehensive analyses of apparent characteristics, mass loss, porosity, uniaxial compressive strength, acoustic emission activity, and other key indicators. These measurements elucidate the impact of the acidic leachate on the physical and mechanical properties of carbonate rocks.

Experimental results demonstrate that the dissolution rate and porosity of the rock samples increase with prolonged exposure time and higher flow rates, whereas the mechanical strength exhibits a corresponding decline. As dissolution progresses, the formation of increasingly thicker fluorite mineral layers on the rock surfaces is observed, which subsequently attenuates the dissolution rate. Furthermore, the failure mode of uniaxial samples shifts from shear-dominated to tensile-dominated damage. The acidic environment of phosphogypsum leachate induces the dissolution of internal minerals within limestone, resulting in significant changes to macromechanical properties.

These findings provide critical theoretical and experimental insights for assessing the stability of karst media under acidic wastewater conditions, as well as for optimizing the safety design of acidic wastewater treatment and tailings management systems.

The seepage in fractured rock masses is non-uniform and anisotropic, with its complexity reflected in the density, orientation, and trace length of individual fractures, as well as the connectivity of fracture networks. The connectivity of fracture networks poses a significant challenge in calculating the seepage parameters of three-dimensional (3D) fractured rock masses. Currently, methods for calculating seepage parameters of 3D fractured rock masses have their own advantages and disadvantages, depending on the model assumptions they used. To analyse the hydraulic anisotropy and permeability coefficients of fractured rock masses, a new method for solving the permeability coefficient of a 3D fractured rock mass based on dense sections is proposed using the dimensionality reduction.

This method involves simulating 3D fracture networks and approximating fractured rock masses using dense sections in different directions. The 3D fracture network is decomposed into multiple continuous two-dimensional (2D) sectional fracture networks, and the graph theory is applied to analysing the hydraulic connectivity and permeability paths. Water head boundary conditions are then set to calculate the permeability coefficient. By leveraging the geometric relationships among lines, surfaces, and volumes in 3D space, the calculated permeability coefficient is expressed as the directional permeability in 3D space, and a permeability tensor for the 3D fractured rock mass is constructed.

By treating the section permeability coefficient as a permeability ellipse, the new method calculates the equivalent permeability coefficient of the section and provides a formula for the equivalent permeability tensor of the rock mass. The scale effect and representation of anisotropy in the rock mass are also discussed. The 3D and 2D fracture networks are constructed, and different sizes of unit cells are intercepted to calculate the permeability coefficient, with a typical unit size determined to be 20 m. The method's feasibility is verified through field water pressure experiments.

This method provides a important reference for solving the permeability coefficients in different directions of heterogeneous fractured rock masses at various scales.

Gas hydrates are ice-like solid substances formed by natural gas such as methane under high-pressure and low-temperature conditions, and are widely found in continental margin sediments and permafrost zones, serving as important methane reservoirs in marine environment. On the one hand, methane released from the decomposition of seafloor gas hydrates enters the atmosphere and exacerbates the greenhouse effect. On the other hand, methane released into sediments and seawater can be converted into organic and inorganic carbon through microbial activities. Therefore, the burial of methane-derived carbon in sediments can effectively reduce the methane flux into the atmosphere and meditate the greenhouse effect.

The South China Sea is an ideal area for harboring gas hydrates due to its tectonic and sedimentary environment. In this area, numerous historical methane seepage events have been reconstructed. To understand the role of gas hydrates in the marine carbon cycle and climate change, it is crucial to obtain in-depth perspectives of the methane release records in the South China Sea. Especially, the transformation of methane in sediments and seawater, as well as the burial of methane-derived carbon are of great scientific significance.

In this paper, we review the triggering mechanisms of gas hydrate decomposition, the methods of reconstructing methane release events, and the transformation processes of methane in cold seeps, with more focuses on the organic geochemical processes in sediments and water column. We summarize the methane release process, methane-derived carbon transformation and burial, and introduce the cutting-edge methodology and related research work for identifying gas hydrate decomposition events based on carbonate, foraminifera, biomarkers and sediment carbon-sulfur-trace element systematics. Based on the previous work, we provide an outlook on the conversion of methane to organic carbon in cold seep environments and a theoretical basis for the future researches concerning the role of methane-derived carbon in the marine carbon cycle.

The bonding performance of the anchor-mortar interface is influenced by multi factors, yet existing studies predominantly focus on single-factor effects, leaving a gap in understanding the combined impact of multiple factors. This study aims to address this gap by systematically investigating the interfacial bonding performance under multifactorial conditions.

The anchor-mortar interface is taken as the research object. Electrochemical impedance spectroscopy is used to characterize the interfacial state and derive electrochemical parameters under different varying conditions. Pullout tests are conducted to quantify the bond strength of the anchor-mortar interface. By correlating electrochemical parameters with pullout load data at the completion of sample curing, the relationship between these parameters and interfacial performance is established. Additionally, the influence of the three factors on the bonding performance of the anchor-mortar interface is analyzed.

Sensitivity analysis of the orthogonal test results reveals that the pullout load is predominantly governed by the anchor rod diameter, whereas the pore solution resistance (R_s) is primarily influenced by the water-cement ratio. No dominant factor is identified for the charge transfer resistance (R_ct). During the early curing stage, two distinct interfacial states are observed under the combined influence of the three factors: A fully developed passivation film and partially developed passivation film. Within the tested parameter range, the pullout load increases with larger fine sand particle sizes and lower water-cement ratios. A positive correlation is observed between the pullout load and both the pore solution resistance (R_s) and charge transfer resistance (R_ct).

These findings provide critical insights for optimizing the formulation and application of anchored structural mortar.

Seabed carbon dioxide (CO₂) geological sequestration technology has gained popularity in the fields of carbon sequestration and carbon neutralization. In the northern South China Sea, favorable conditions for the formation of CO₂ hydrates exist in seabed sediments, where hydrates forming in cracks and pores may block the further upward migration of CO₂ and generate self-sealing capacities. However, the effects of CO₂ leakage in fractures and the instability of hydrate plugging remain unclear.

A visualization experimental platform for hydrate growth and the instability process under water injection supercharging at high pressure and low temperature was used to observe CO₂ hydrate formation. The platform simulated the conditions of seafloor sedimentary cover at 2℃ and 3～4 MPa, and evaluated hydrate instability and plugging effects using parameters of breakthrough pressure, breakthrough pressure difference, duration, permeability coefficient at the initial instability stage, and plugging rate.

The experimental results show that hydrate formation proceeds through four stages: Nucleation, expansion, formation, and aggregation. Hydrates formed in cracks effectively block the migration of fluids such as water and CO₂; however, instability begins when fluid pressure increases and reaches the critical breakthrough pressure. The instability process can be divided into two stages: Particle size degradation and surface friction failure. The hydrate mass core becomes unstable first, while the sealing state persists until the surface of the hydrate fails due to friction. The breakthrough pressure ranges from 6.414 to 6.966 MPa, and the breakthrough pressure difference is between 2.403 and 3.203 MPa. Hydrate instability is primarily influenced by flow rate, with the flow rate affecting the instability rate through interface effects. The breakthrough pressure of hydrates is mainly determined by temperature and pressure, while flow rate influences the exact time when hydrates enter instability. At 3～4 MPa seafloor sedimentary cover, the sealing rate is 99.0%～99.6%, and the permeability coefficient at the initial instability stage ranges from 0.555×10⁻³ to 1.260×10⁻³ μm².

The experimental results offer a reference for risk assessments of overlying layers in similar conditions in the South China Sea for CO₂ seabed geological sequestration. To maintain the sealing effect of CO₂ hydrates, the pressure difference between the capped hydrate layer and the actual seabed pressure should be less than 2 MPa.

Land resource assessment and specialty industry cultivation are pivotal for China's rural revitalization and poverty alleviation initiaives. To optimize regional agricultural planning and specialty sector development, this study implemented a selenium-rich land resource survey in Tunliu District, Changzhi City, Shanxi Province.

A comprehensive land quality evaluation framework was established, integrating three dimensions: Selenium-rich industrial potential, ecological integrity, and arable land productivity. The fuzzy mathematical method, entropy weighting, and composite index modeling were synergistically applied for land classification, with spatial patterns visualized through ArcGIS.

The results show that: ①54.47% of the study area contains medium-to-high selenium concentrations, predominantly clustered in eastern regions. Arable land productivity demonstrates spatial heterogeneity, with lower values in western zones versus higher eastern values. ②299.33 km² (26.21% of total) of first-class quality land was identified in eastern plains. ③Wheat, chili peppers, and bell peppers exhibit 100% selenium enrichment compliance with crops in good condition. ④Based on land and crop evaluation results, and considering spatial planning, the land is classified into three types: A, B, and C. Zone A (Premium): Supports selenium-rich wheat/vegetable cultivation and agro-tourism (eastern plains). Zone B (Transitional): Suitable for diversified cropping with selenium supplementation. Zone C (Marginal): Recommended for agricultural product processing and trade hubs due to suboptimal selenium (<0.30 mg/kg) and nutrient levels.

This study provides theoretical support and scientific recommendations for planning the selenium-rich agricultural industry in Tunliu District and for its integrated regional development.

In tunnel engineering, the prerequisite for tunnel design and construction safety is to accurately assess the amount of deformation of the rock surrounding a tunnel.

In this work, the firefly algorithm (FA), whale optimization algorithm (WOA), and gray wolf optimization algorithm (GWO) are combined with optimized support vector regression (SVR), and three intelligent hybrid swarm optimization prediction models are constructed to predict the deformation of extruding surrounding rock tunnels. A database containing 62 samples was constructed, and seven initial parameters of tunnels and surrounding rock were selected as the input parameters of the prediction models, with the radial deformation of tunnels as the output quantity. The coefficient of determination (R²), root-mean-square error (RMSE), and mean absolute error (MAE) were selected as the evaluation indices of the model's prediction performance. Finally, the effects of different input parameters on the prediction results of tunnel rock deformation were evaluated via normalized mutual information values.

Compared with the GWO-SVR and WOA-SVR models, the FA-SVR model demonstrated superior predictive performance during both the training and testing phases. The corresponding R² values were 0.9634 and 0.9648, the RMSE values were 18.786 and 14.699, and the MAE values were 9.460 and 11.170 for the training and testing sets, respectively. The ranking of predictive capability was as follows: FA-SVR>WOA-SVR>GWO-SVR. The firefly algorithm, whale optimization algorithm, and gray wolf optimization algorithm can improve the prediction performance of the support vector regression model. The FA-SVR model has the best prediction effect, and the optimized hybrid prediction model performs significantly better than the classical models. The sensitivity analysis reveals that the joint frequency is the most important parameter affecting the predicted value of deformation of the rock surrounding a tunnel.

The research results can provide an important reference for the safety control of tunnel engineering.

Quantitative characterization of hydrocarbon generation, expulsion, and retention intensity in high to over-mature shale gas reservoirs represents a critical scientific challenge for deep resource evaluation. The Permian Wuchiaping Formation (Wu Second Member) shale gas reservoir in the Hongxing area, southeastern Sichuan Basin (with proven reserves exceeding 10¹¹ m³), presents complex geological characteristics including thin-layer distribution, strong heterogeneity, and multi-stage tectonic modification, making it difficult to precisely characterize the spatiotemporal evolution of hydrocarbon generation-expulsion-retention processes using traditional evaluation methods.

This study established a multi-dimensional evaluation system integrating thermal simulation experiments, hydrocarbon potential methods, and generation kinetic modeling with mutual verification to systematically reconstruct the complete evolutionary model of the Wu Second Member shale gas reservoir from hydrocarbon generation to preservation, enabling quantitative characterization and spatial prediction of resource potential.

Thermal simulation results indicate that the total hydrocarbon generation rate of the studied samples reached 456 mg/g TOC, including total gas generation of 349.68 mg/g TOC (76.7%) and total oil generation of 106.59 mg/g TOC (23.3%); oil-phase products were primarily expelled (103.35 mg/g TOC) with minimal retention (3.24 mg/g TOC). Hydrocarbon potential evaluation revealed that Wu Second Member shale entered the hydrocarbon generation threshold at Ro=0.5% and the expulsion threshold at Ro=0.8%, with an original hydrocarbon generation potential index reaching 550 mg/g. The present-day generation, expulsion, and retention intensities in the Hongxing area and surrounding regions reached maximum values of 90×10⁸ m³/km², 68×10⁸ m³/km², and 28×10⁸ m³/km², respectively, with high spatial coupling of their centers primarily concentrated in three key areas: Wanzhou-Hongxing-Enshi. Hydrocarbon generation kinetic modeling further revealed that the peak gas generation intensity in the study area could reach 50×10⁸ m³/km², with maximum gas retention intensity of 16×10⁸ m³/km². Through comprehensive analysis of key preservation factors including burial depth, structural stability, and sealing capacity, the present-day residual gas intensity distribution pattern was quantitatively determined, confirming the Hongxing-Wanzhou region as the optimal exploration target area.

This study not only elucidates the spatiotemporal evolution patterns of hydrocarbon generation, expulsion, and retention in the Permian shale gas reservoir of the Sichuan Basin but also provides theoretical foundation and practical guidance for refined exploration of deep to ultra-deep shale gas reservoirs.

Automatic pickup of effective events is an important part of microseismic monitoring, and the accuracy of pickup directly affects the accuracy and reliability of subsequent seismic source localization and seismic source mechanism inversion.

In this paper, a 10-layer U-Net neural network model framework is constructed, the original microseismic data from 3D finite-difference simulation and the raw microseismic data from the measured gas storage reservoirs are made into labeled images, which are cut into 128*128 sized slices and input into the U-Net neural network for learning, and then the output of predicted slices is outputted and merged, and then the predicted images are binarized, and the microseismic effective events are extracted in the end of the P-wave first arrivals. This makes the edge segmentation of background noise and effective signal image more fine, and improves the efficiency and accuracy of automatic picking up of effective microseismic events.

Quantitatively analyze and compare the pickup rate, wrong pickup rate and pickup error of U-Net method and STA/LTA method, the test results show that the pickup effect of U-Net is better than that of STA/LTA method, and U-Net also has a strong anti-jamming ability and generalization ability; Evaluate the effect of different label widths on the first-to-pickup results, the results show that the label pickup effect based on the event's primary cycle is The results show that the label pickup effect based on the main cycle of the event is the best.

The U-Net neural network first-to-automatic pickup algorithm established in this paper is an important part of the highly efficient and high-precision reservoir integrity microseismic intelligent monitoring system, which is of great significance to improve the level of microseismic monitoring technology in China.

To investigate the salinization of groundwater impacted by Late Pleistocene/Holocene transgression, current seawater intrusion, and evaporation, and to comprehend the consequences of marine transgression events and seawater intrusion due to groundwater over-exploitation on groundwater salinization, two shallow aquifers were chosen for research in the Cangzhou area.

Using the SEAWAT software, a paleo-hydrogeological model was developed to simulate the evolution of groundwater salinity since the Holocene, relying on a series of paleo-environmental evolution data.

The results suggest that the distribution of shallow groundwater salinity is impacted by the Holocene transgression/regression. A traditional fingering process of saline water infiltration in shallow areas was discovered at an average rate of 23 mm/a, resulting from transgression events. Despite the low-permeability aquitards, saline infiltration persists over extended periods, reaching depths of up to 140～160 m B.S.L.

Trapped marine water from the Late Pleistocene and Holocene transgression events remains present and has not been flushed out. The salt transport in the coastal aquifer-aquitard system has yet to reach an equilibrium state, potentially affecting the groundwater quality of deep confined aquifers.

To deepen the understanding of the spatial and temporal differences in rift formation and evolution among different tectonic units within the Pearl River Mouth Basin.

Based on 2D seismic profile data, this paper discusses the differences in pre-existing structures, basement lithology, fracture systems and tectonic evolution of different tectonic units by means of tectonic analysis, balanced cross-section restoration, and calculation of fracture activity rates, and explores the causes of the depression tectonics in the basin in the context of magmatic activities and dynamics.

A series of NE-trending thrust faults and conjugate NW-trending pre-existing thrust faults were developed on the basement pre-existing tectonics of the Pearl River Mouth Basin; Faults with NE-NEE -trending are major in the western part of Zhu Ⅲ, Zhu Ⅱ and Zhu Ⅰ, while faults with near-EW-NWW-trending are major in the eastern part of Zhu Ⅰ and Zhu Ⅱ, controlling the tectonic pattern of the basin during the rifting period; the rifting impacts are gradually reduced from east to west, and the pre-existing faults in the eastern part of Zhu Ⅰ are more active.

During the rifting period, the main fractures were developed along the basement pre-existing lithology, and the main fault system of the same sedimentary trunk in ZhuⅠ and ZhuⅡ depression changed clockwise from NW-NEE to stretching to EW-NW-trending and strike-slip dominated, with different tensile and shear strengths due to the differences in basement pre-existing structure and lithology, and controlled by the surrounding plate movement, magmatic activities and regional stress field changes. The rift structure changes from north to south from a long and narrow graben and half-graben, which is thick at the bottom and thin at the top, to a wide and slow graben and half-graben, which is thick at the top and thin at the bottom. In the late stage of the rift, due to the influence of depth-dependent stretching mode, the rift structure changes from a long and narrow graben and half-graben to a wide and slow graben and half-graben.

In Zigui Basin of the Three Gorges Reservoir region, prone-sliding strata mainly composed of weak-hard interbedded strata are widely distributed. Under the action of long-term reservoir water immersion, erosion and rainfall, the formation rock and soil bodies deteriorate and become an important internal cause of reducing landslide stability and affecting project safety.

Taking rock and soil mass of weak-hard interbedded strata as the research object, finite discrete element method (FDEM) is used to calibrate the mechanical properties of hard and soft rocks in the weak-hard interbedded strata under different wetting-drying cycles. Then the mesh is redivided by the improved Tyson polygon program, and the embedding function of zero thickness cohesive force unit is realized. The FDEM numerical model of landslide-anti-slide pile system in weak-hard interbedded strata formation is proposed and established. Finally, the formation process of landslide cracks and the embedding mechanism of anti-slide piles under different wetting-drying cycles are studied.

The results show that: ① The number of simulated landslide cracks increases with the increase of the number of wetting-drying cycles, and the cracks width also increases gradually. The results of simulation are basically consistent with those of the site of Majiagou landslide. ② The simulated cracks of the landslide-anti-slide pile system show two evolutionary patterns: one is that the cracks spread downward from the rock mass on the top side of the pile along the pile body; the other is that the cracks gradually extend from around the anti-slide pile to the inside of the slide body, connecting with the transverse cracks and vertical cracks, and finally forming large through cracks. ③ When the number of wetting-drying cycles increases, the horizontal displacement, bending moment and shear force of anti-slide pile also increase. ④ The cracks in the weak-hard interbedded strata bedrock of the anti-slide pile have the characteristics of localized development, and with the increase of the number of wetting-drying cycles, the stress in the region gradually decreases, the displacement and strain gradually increase, and the corresponding cracks become more and more intensive.

The results of this study can provide support for the prevention and control of landslide in weak-hard interbedded strata under different wetting-drying cycles.

The Naneng gold deposit is an important medium-sized Carlin type gold deposit in southeastern Yunnan, and studying its genesis is of great significance for searching for such gold deposits in southeastern Yunnan.

Two generations of pyrite (PyI and PyII) were found to develop in the Naneng gold deposit during detailed field survey and indoor observation, and trace elements and sulfur isotopes of gold-bearing minerals are analyzed by LA-ICP-MS to constrain the source of ore-forming materials and ore genesis.

LA-ICP-MS analyses show that PyI contains a small amount of Au (mean 6.37×10⁻⁶), which is relatively enriched in elements such as Co, Ni, Se, W; The distribution characteristics of trace elements in PyII and PyI are similar, but the content of Au (mean 68.02×10⁻⁶) is relatively high, and As, Sb, Cu elements are enriched in PyII; The average Au content of arsenopyrite is 36.02×10⁻⁶, and arsenopyrite is mainly enriched in elements such as As、Ni、Sb、Se、Au, while Zn, Ag, Hg and Tl elements are low. In addition, gold-bearing minerals in the Naneng gold deposit have consistent in situ δ³⁴S values, ranging from 13.7‰ to 16.5‰, indicating that the S of gold-bearing minerals mainly come from the surrounding rocks.

It is preliminarily concluded that PyI was formed in a relatively stable environment by medium to low temperature hydrothermal fluid from the same source rich in trace elements such as Au、As、Sb, and a small amount of Au precipitated simultaneously with PyI in the form of solid solution (Au⁺). In the PyII stage, the intense tectonic activity in the area caused ore-forming fluid to upswell, and after sulfidation reaction with surrounding rock strata, the concentration of H₂S in the fluid decreased, Au-HS complex became unstable, and Au supersaturated precipitation was enriched in PyII in the form of nanoscale inclusions (Au⁰).

Block Fan 151 is a low-permeability beach-bar sandstone reservoir with poor overall physical properties and high heterogeneity, resulting in low oil recovery and significant amounts of residual oil during development. It is essential to analyze the influence of reservoir heterogeneity on the distribution of residual oil and identify enrichment areas. Furthermore, calculating the reservoir heterogeneity comprehensive index plays a crucial role in quantitatively characterizing heterogeneity. Therefore, improving the accuracy of calculating the comprehensive index can provide a basis for predicting favorable areas for oilfield development and finding residual oil.

To improve the accuracy of the comprehensive reservoir heterogeneity index calculation, this study proposes the AHP-CRITIC combined weighting method. This method determines the composite weight of evaluation indicators using both subjective and objective data, overcoming the limitations of a single weighting approach.

Quantitative analysis of the heterogeneity of the 2⁴ layers in the Upper Es4 Member of Block Fan 151 shows that the heterogeneous comprehensive index I ranges from 0.27 to 0.73, with about 63% of the values falling between 0.4 and 0.65.

The target formation in the study area exhibits moderate to strong heterogeneity, and the distribution of high values of the comprehensive heterogeneity index I aligns closely with the high-value areas on the residual oil saturation contour map. This indicates that the AHP-CRITIC combined weighting method effectively assigns weights to the evaluation parameters and establishes a quantitative evaluation criterion for the heterogeneity of this reservoir. This approach offers a new method for the quantitative characterization of reservoir heterogeneity.

Deep Earth exploration is a multidisciplinary scientific endeavor aimed at uncovering the structure, dynamics, and evolution of continents and their margins. Understanding of the Earth’s interior is crucial for advancing scientific knowledge and comprehending the fundamental processes that shape our planet. Over the past half-century, many countries worldwide have implemented various deep Earth exploration programs, accumulating valuable experience and achieving significant breakthroughs in technology and methods. These advancements provide important references for deep Earth exploration in China.

This paper analyzes the technical approaches and achievements of representative deep Earth exploration programs in the United States, Europe, and Australia since the 21st century, summarizing the latest progress of these programs.

Six frontiers and key potential directions of deep Earth exploration are summarized, including seismic tomography for deep Earth structure detection, magnetotellurics for mineral resource exploration, GNSS monitoring for Earth's motion and state changes, coupled surface-to-deep Earth processes, advanced data processing, analysis and modeling capabilities, and open data sharing. These are expected to provide informational support and references for the “SinoProbe-II” deep exploration program, the “Earth CT” international cooperative research program, and the National Science and Technology Major Projects focused on deep Earth and mineral resources exploration in China.

By analyzing the characteristics of geological core drilling, we systematically classify and summarize methodologies for trajectory control.

The following results are obtained: First, the primary objective of primary directional boreholes is to obtain the core of the target layer. Design methods for parameters such as inclination angle, orientation, and displacement alongside their depth-dependent variations were analyzed. The applicable conditions and drawbacks were clarified, providing ideas for the use of primary directional boreholes in drilling construction of depths less than 500 meters. It was pointed out that deep boreholes should be used in conjunction with other measures. Second, in terms of packed hole assemblies for geological drilling, we analyzed the use of conventional hole assemblies and large-diameter hole assemblies, and proposed the mechanical theory of the wire coring string with packed hole assembly. Third, regarding controlled directional drilling technology, we analyzed its application in drilling deviation correction and lateral drilling obstacle avoidance. We pointed out the advantages and disadvantages of different methods, indicating that small-diameter bottomhole power drilling tools have obvious advantages. However, due to the requirements of geological coring technology, they have many limitations in geological core drilling.

This study reviews the status of geological core drilling trajectory control technologies, identifies key influencing factors, and evaluates various control techniques to enhance exploration precision.

Landslides are geological disasters that cause significant damage to both natural and social environment. Effective landslide susceptibility assessment is crucial for disaster prevention and mitigation. Existing landslide databases are often used as the primary data source for susceptibility assessments. However, due to delays in updates, these databases suffer from issues such as poor timeliness and incompleteness. Moreover, traditional landslide susceptibility assessment methods primarily rely on static data (e.g., topography, geology, and hydrology) and lack dynamic data (e.g., surface deformation), making it difficult to fully characterize the deforming landslides and reducing assessment reliability.

This study combined optical remote sensing technology and synthetic aperture radar interferometry (Interferometric Synthetic Aperture Radar, InSAR) to identify landslides in the study area and obtain surface deformation as a dynamic evaluation factor. In combination with static evaluation factors, two methods—joint training and weighted superposition—were employed, alongside the Maximum Entropy (MaxEnt) model and the Iterative Self-Organizing (ISO) clustering algorithm to assess and categorize landslide susceptibility in Shimian County.

The findings are as follows: (1) By integrating optical remote sensing and InSAR technologies, 139 landslides are identified in the study area. High-risk landslide zones in Shimian County are predominantly located along riverbanks and roadsides. The distribution of landslide disaster points aligns well with the zoned areas. (2) Incorporating the InSAR deformation factor enhances the susceptibility accuracy by 6.1% (AUC=0.921) and substantially reduces the occurrence of false positives and false negatives, thereby improving overall model accuracy.

This study demonstrates the advantages of incorporating InSAR deformation data into landslide susceptibility models, offering valuable support for landslide disaster prevention in Shimian County.

The spatial distribution analysis of earthquake-induced landslides offers critical insights for identifying potential geological disasters in affected regions, which is fundamental for informing post-disaster reconstruction planning, relocation strategies, site selection processes, and the development of effective geological disaster mitigation measures.

Taking the earthquake that struck Luding County, Ganzi, Sichuan Province, on September 5, 2022, as a case study, earthquake-induced landslides were initially identified using artificial visual 3D remote sensing data. This analysis was based on an optical image (DOM) with a resolution of 0.2 meter and a digital elevation model (DEM) with a resolution of 0.5 meter, both acquired post-earthquake. Field investigations and subsequent corrections were performed to validate and finalize the landslide inventory. Subsequently, the relationships between the distribution of earthquake-induced landslides and various geological factors, including topography, geological structures, and earthquake parameters, were systematically analyzed.

①The Luding earthquake triggered 9248 landslides, covering an area of approximately 680 km², with the majority classified as small- to medium-sized. The highest landslide density was observed at the tectonic intersection of the Xianshuihe fault, Daduhe fault, and Jinping mountain fault. The cumulative landslide area reached approximately 45.57 km², with an average landslide area of 4941 m². ② The spatial distribution of landslide in the earthquake-affected region is predominantly controlled by PGA and fault structures, with the majority of landslides concentrated in areas where PGA exceeds 0.6 g and within 1 km on either side of the seismogenic fault. Furthermore, landslide occurrence exhibits a negative correlation with proximity to water systems and roads. At a local scale, topographic factors significantly influence landslide distribution, with the highest frequency observed at elevations ranging from 1200 to 2400 m, on slopes inclined between 30° and 60°, and predominantly facing east or southeast. Additionally, landslides are more prevalent in areas underlain by hard rock strata. ③ The number and area of landslides exhibit an exponential relationship with the magnitude of the Luding earthquake. Leveraging high-precision data, our analysis identified a significantly higher number of earthquake-induced landslides compared to previous studies, with a reduced minimum landslide area and an increased total affected area.

The findings of this study have been implemented to support post-disaster recovery and reconstruction efforts in the Luding earthquake-affected region, providing a scientific basis for enhancing resilience and reducing future earthquake risks.

To improve the engineering properties of clay and increase the utilization of waste steel slag (SS).

Geogrid reinforcement was employed, followed by direct shear tests, cyclic shear tests, and post-cyclic direct shear tests conducted on steel slag-clay mix, sand-clay mix, and pure clay. The study investigated the strength characteristics, damping ratio, shear stiffness changes, and displacement of the mixed soil reinforcement-soil interface under various conditions, including different steel slag contents, vertical stress, moisture content, and shear amplitudes.

The test results indicate that steel slag significantly enhances the shear strength of the clay-reinforcement interface, with improvement being more effective than conventional sand-modified clay. The steel slag-clay mixed soil exhibited higher damping ratio and shear stiffness, suggesting better vibration damping and energy dissipation properties. Among the various mixtures, the steel slag-clay mix with 40% steel slag content demonstrated the best shear strength, damping ratio, and shear stiffness. Additionally, the shear strength of the steel slag-clay mixed soil increased after cyclic loading compared to pre-cyclic direct shear conditions. The results also show that moisture content has a more significant impact on shear strength, shear stiffness, and damping ratio than vertical stress and shear amplitude.

The steel slag-clay mixed soil exhibits improved damping and energy dissipation properties under cyclic shear loading. The experimental findings provide a theoretical basis for using steel slag as a substitute for sand to improve clay soils.

Lithology identification is a crucial step in the process of oil and gas detection and exploration, providing important guidance for exploration positioning, reservoir evaluation, and the establishment of reservoir models. However, traditional manual lithology identification methods are time-consuming and labor-intensive. Although classical deep learning models achieve high identification accuracy, they often have a large number of parameters. To enhance model accuracy while reducing the number of parameters, the aim of this research is to make the model suitable for real-time lithology identification.

This paper first collected a dataset of 3016 rock images consisting of eight types of rocks, including dolomite and sandstone. Based on the lightweight convolutional neural network ShuffleNetV2, the paper proposes a Rock-ShuffleNetV2 lithology identification model (hereafter referred to as the RSHFNet model). The model incorporates the Convolutional Block Attention Module (CBAM) and Multi-Scale Feature Fusion Module (MSF) into the basic network to enhance feature extraction capabilities and improve identification performance. Additionally, the number of stacked ShuffleNetV2 units is optimized to reduce the model's parameters.

The experimental results show that the RSHFNet model achieved an accuracy of 87.21%, which is a 4.98% improvement over the baseline model. Furthermore, the model's parameters and floating-point operations were reduced to 8.69×10⁶ and 9.3×10⁷, respectively, representing 67% of the model's parameters and 63% of the floating-point operations of the baseline model. This reduction significantly decreases the model's size. Additionally, the RSHFNet model demonstrates superior overall performance compared to existing convolutional neural networks.

The proposed RSHFNet lithology identification model offers high recognition accuracy and strong generalization capabilities while being more lightweight, providing a new approach for real-time lithology identification in the field.

The interpretation results of SBAS-InSAR exhibit multiple solutions, making it uncertain to directly use the interpreted deformation points for identifying potential landslide-prone areas. Therefore, taking the north bank of the Qingjiang River (Changyang Section) as the study area, this study proposed a method to comprehensively optimize SBAS-InSAR interpretation results by incorporating landslide susceptibility evaluation.

First, the deformation points interpreted by SBAS-InSAR were analyzed using clustering and outlier detection (Anselin Local Moran's I), and low-value cluster deformation points were retained. Subsequently, eight factors, including elevation, slope, and slope aspect, were selected to evaluate and generate a landslide susceptibility zoning map using the information value method. The reliability of the landslide susceptibility evaluation was confirmed by an ROC curve, with an AUC value of 0.844.

The optimized SBAS-InSAR results were obtained by filtering low-value cluster deformation points based on a threshold value (v ≤ -10 mm/a) and incorporating the landslide susceptibility zoning map. Field verification in selected areas shows that the number of deformation points was reduced after optimization, and their distribution characteristics were more consistent with the historical landslide development in the study area. Additionally, taking the Yupingcun landslide group and the Pianshan landslide as typical cases, the surface deformation values monitored by SBAS-InSAR and GNSS at the same time were compared. In the case of the Yupingcun landslide, the difference between surface displacement values monitored by SBAS-InSAR and GNSS ranged from 0 to 7.87 mm, with an average difference of approximately 2.23 mm and an RMSE of 3.67.

The proposed optimization method for SBAS-InSAR interpretation was demonstrated to be both practical and reliable, providing valuable insights into the application of InSAR technology in the field of geological disasters.

Karst groundwater resources are vital water sources in China. Due to the combined effects of global climate change and intense human activities, such as coal mining, groundwater quality in the Jinci Spring area has deteriorated. Identifying water environmental issues and understanding the groundwater pollution mechanisms in the karst critical zone of this area are crucial for the protection of karst groundwater resources.

The groundwater quality in the spring area was evaluated using the entropy weight method and water quality index. Based on the water quality assessment, isotopic tracing of sulfate oxygen and nitrate nitrogen in groundwater was further performed to trace pollution sources. Additionally, the pollution pathways in karst groundwater were identified through the analysis of inorganic carbon isotopes, strontium isotopes, and sulfur isotopes.

The results showed that the average sulfate concentration in karst groundwater was 572.07 mg/L, while the nitrate concentration in pore water reached 424.72 mg/L, indicating obvious sulfate and nitrate pollution in the groundwater from the study area. Sulfur isotopes in the polluted karst water exhibited a remarkable negative deviation, and the strontium and carbon isotopic characteristics of nitrate-polluted karst water resemble to those of deep pore water.

The primary source of excessive sulfate in groundwater is sulfide oxidation and gypsum dissolution, while sewage discharge and manure input are the important sources of nitrate contamination. The main pollution pathways in karst aquifers include reverse recharge from pore water and cascade recharge from upper-layer goaf water. This study provides important scientific evidence for the control of karst groundwater pollution and the rational development and utilization of karst water resources in the Jinci Spring area.

Under complex geological conditions, the mechanical properties of the surrounding rock in underground water-sealed storage caverns are weakened due to construction disturbances, accompanied by stress redistribution and deformation accumulation, leading to the higher risk of localized instability. The creep effect further exacerbates the deformation and plastic failure of the surrounding rock, posing a threat to the long-term stability of the cavern. Therefore, the study of surrounding rock stability should fully utilize monitoring data to assess the state of the surrounding rock and guide construction and operation.

Based on the comprehensive analysis of multi-source monitoring data, such as surrounding rock displacement, anchor stress, and borehole wave velocity, numerical experiments using orthogonal design were employed to invert the mechanical parameters of the rock mass. Additionally, pore water pressure, surrounding rock deformation laws, stress variation, and plastic zone distribution characteristics under layered excavation of the cavern during construction were analyzed. Finally, the stability characteristics of the underground water-sealed storage cavern under long-term water-sealing conditions were evaluated using a creep model of the underground cavern group.

The results show that the deformation of the surrounding rock sharply increases when passing through the monitored section during excavation, with a maximum increment of approximately 3 mm, and then tends to converge. The area affected by the J₁ jointed zone exhibits higher displacement. The overall stress of the anchor rod system is relatively low, and the stress of the anchor rod is synchronized with the deformation of the surrounding rock. The depth of the loosening zone of the surrounding rock is approximately 1.0 m. During construction period, the pore pressure in the excavation area approaches 0 MPa, and the seepage flow of cavern and deformation of surrounding rock are densely distributed along the J₁ jointed zone. The excavation of the middle and lower layers causes the displacement at the intersection of J₁ and the arch line to increase by 90.4% and 28.7%, respectively. The plastic zone in the sidewalls deepens layer by layer, with a maximum depth of 9.2 m. The long-term deformation characteristics of the surrounding rock are manifested as sidewall convergence > floor uplift > crown settlement. The cumulative deformation at the intersection of the J₁ and the arch line during the first year accounts for 92% of the total deformation over 30 years, with a maximum deformation of 27.1 mm. Under the creep effect, stress is gradually released, and the stress distribution tends to become more uniform. The plastic zone near the J₁ expands significantly, while the plastic range in the intact granite area is relatively small, indicating higher long-term stability, indicating that the geological structure-affected zone is the main instability risk zone.

This study provides engineering significance and reference value for stability evaluation during both the construction and operational phases of underground water-sealed storage caverns.

The Upper Paleozoic sandstone reservoirs in the Xinzhao area, northern Ordos Basin are rich in natural gas and characterized by underpressure. The mechanisms of paleo-pressure evolution and underpressure formation are unclear, constraining the understanding of tight sandstone gas accumulation and the enhancement of natural gas production.

In this study, we comprehensively analyzed the petroleum charging history in the second member of the Shanxi Formation using fluid inclusion petrographic observation, micrometry, and laser Raman analysis. Subsequently, we obtained the paleo-pressure during the key period of reservoir formation. The paleo-pressure evolution history was reconstructed by the basin simulation method, and the coupling relationship between paleo-fluid pressure evolution and petroleum charging was established. The relationship between the causes of underpressure and tight gas accumulation is further discussed.

The results indicate that: (1) CO₂ was captured in the second member of the Shanxi Formation in the Xinzhao area from 170 to 180 Ma, when the source rock was in the middle to low maturity stage, and the methane inclusion was captured in the peak of hydrocarbon generation from 138 to 121 Ma. (2) Overpressure in the second member of the Shanxi Formation began to develop in the Early Jurassic and reached a maximum paleo-pressure and paleo-pressure coefficient of 50 MPa and 1.31, respectively, by the end of the Early Cretaceous. (3) The decrease in formation pressure in the second member of the Shanxi Formation, caused by temperature decrease, pore rebound, and gas diffusion, accounted for 49%, 14.5%, and 36.5% of the total formation pressure decrease, respectively.

The tight gas reservoir of the second member in the Shanxi Formation has undergone a pressure evolution process from normal pressure to medium overpressure to normal pressure and finally to underpressure. Hydrocarbon generation supercharging and pressure conduction are the primary factors contributing to ancient overpressure. Temperature decrease and natural gas diffusion are the primary factors contributing to the formation of underpressure in the second member of the Shanxi Formation.