The overpressure in the Triassic system of the western part of the central depression in the Junggar Basin is strong and has a complex genesis. However, research on the distribution and genesis of Triassic overpressure is relatively limited at present.

Based on data such as drilling fluid relative density, measured formation pressure, and logging data, methods such as logging curve combination, the Bowers method, and acoustic velocity-density crossplots were used to analyze the logging response characteristics of overpressure in the Triassic system of the western part of the central depression, and to explore the genesis and main controlling factors of overpressure.

The mudstones of the Triassic overpressure section exhibit characteristics of high sonic time difference and low resistivity. The neutron density and neutron porosity of the mudstone deviate from the normal compaction trend line, but the degree of deviation varies across different well areas.

The current Triassic overpressure is mainly caused by the combined effects of unbalanced compaction and deep pressure transmission. Affected by the characteristics of the Triassic lithological assemblage, sedimentary rate, and fault activity intensity, there are significant differences in the contribution of unbalanced compacted overpressure across different well areas. Particularly in the Karamay Formation: the Shawodi area exhibits the largest contribution, followed by the Moxizhuang area, and the Zhengshacun area shows the smallest contribution. The research results provide a deeper understanding of the mechanism of deep-ultra-deep overpressure in the western part of the central depression of the Junggar Basin.

The construction of deep tunnels is influenced by various geological activities, among which geothermal activity severely affects construction safety and efficiency. Currently, research lacks case studies on the causes of geothermal phenomena.

This study focuses on a proposed highway tunnel in Xinjiang (with a burial depth of 1348 meters) as a case example. By employing geophysical prospecting, drilling, hydrogeochemical analysis, thermal infrared remote sensing, and drones, the engineering geological and hydrogeological characteristics of the tunnel were obtained. The study also examined the distribution of hot springs and other thermal features near the tunnel.

Results show that the hot springs are only distributed in the valley area northeast of the intersection of the F36 and F37 faults. There exists a low-resistance rock body fracture zone underground in the study area, particularly near the faults and hot spring points. Additionally, the mineralization degree of hot spring water samples significantly differs from that of the Arxan River, and the underground temperature is slightly higher than that of the surrounding strata. Based on this analysis, the mechanism of geothermal water formation in the study area is elucidated: geothermal water is not replenished by the nearby Arxan River but by atmospheric precipitation and snowmelt from over three kilometers away. The groundwater converges near the intersection of the F35, F36, and F37 faults, where it encounters a deep heat source at a depth of about 200 meters, heating the high-temperature groundwater, which then flows to the surface along the fractures at the fault intersection. Additionally, the Analytic Hierarchy Process (AHP) was used to evaluate the thermal hazards of the proposed tunnel routes. Four factors were considered as the main influencing factors: faults, ground temperature, tunnel water inflow, and surrounding rock lithology. The evaluation results show that the B8 route scored the lowest, indicating the least impact from thermal hazards, making the B8 route the optimal choice.

This study elucidates the formation mechanism and distribution patterns of geothermal activity in deep-buried tunnels, providing a scientific basis for thermal hazard mitigation in high-altitude mountainous tunnel engineering.

In recent years, significant progress has been made in the exploration of conventional sandstone reservoirs in the Jingjingzigou Formation of the Jinan Depression, Junggar Basin, with tertiary reserves exceeding 100 million tons and promising exploration prospects. Although the primary source rock, the Middle Permian Lucaogou Formation, has been identified based on previous research, studies on the geochemical characteristics of these source rocks and oil-source correlations remain limited.

This study combines a comprehensive set of tests, including total organic carbon (TOC), rock pyrolysis, and biomarker analysis, to investigate the geochemical properties of source rocks from various intervals of the Lucaogou Formation and to explore the oil-source correlations for the Middle Permian.

The results indicate that the Lucaogou Formation can be divided into three sections based on logging curve characteristics. The P₂l₁ and P₂l₂ intervals are high-quality source rocks, characterized by high organic carbon content, hydrocarbon generation potential, and soluble organic matter, with organic matter types of Ⅰ-Ⅱ₁ and early-to-peak maturity, with P₂l₁ being superior. The P₂l₃ interval is predominantly composed of "non-general" source rocks with type Ⅰ-Ⅱ₁ organic matter and high maturity, influenced by the overlying environment. The molecular geochemical characteristics suggest that the source rocks formed in reducing environments. P₂l₁ corresponds to saline water, P₂l₁ represents fresh-brackish water, and P₂l₃ is intermediate, all conditions conducive to organic matter preservation. In terms of biological composition, the Lucaogou Formation contains two primary hydrocarbon-generating parent materials: Green algae and cyanobacteria. The presence of green algae is indicated by age-related biomarkers (C₂₈ steranes), while cyanobacteria are identified by the presence of β-carotene and medium-chain monomethyl alkanes. The hydrocarbon-generating organisms differ across intervals: P₂l₁ and P₂l₃ are predominantly composed of aquatic organisms, particularly cyanobacteria, while P₂l₁ contains both aquatic (green algae) and terrestrial plant input. Variations in lake basin water salinity are a key factor influencing the proliferation of cyanobacteria and green algae in different source rock intervals. C₃₀ αα-hopane is abundant in P₂l₁ and P₂l₁, but absent in P₂l₃. Based on the analysis of sterane and hopane isomerization parameters, the C₃₀ αα/αβ ratio may serve as a potential maturity indicator. Permian crude oils in the Jinan Depression can be classified into three types. Type A and Type B correspond to the source rocks of P₂l₁ and P₂l₂, respectively, while Type C crude oil exhibits characteristics different from the P₂l source rocks and may be correlated with the mudstone of the Jingjingzigou Formation.

This study provides valuable insights for future oil and gas exploration and development in the Jinan Sag.

The primary goal of this study is to establish a graptolite biostratigraphic framework for the Renheqiao Formation. To achieve this, the research focuses on the Banpo and Chadi sections in Shidian County, Baoshan City, Yunnan, which are critical outcrops for biostratigraphic analysis in the area.

A combination of high-resolution biostratigraphic and lithologic investigations was conducted to precisely define the stratigraphy and identify key biozones within the formation.

The Renheqiao Formation in the study area is approximately 71.6 meters thick, with a basal bed of about 25 cm of paleo-weathering crust. It unconformably overlies the Pupiao Formation, indicating that the study area was subaerially exposed during the Late Ordovician. Based on careful fieldwork and high-resolution surveys, a total of nine graptolite zones were identified, spanning from the upper Hirnantian in the Ordovician to the Silurian Llandovery Telychian stage. These zones are identified in ascending order as follows: the Metabolograptus persculptus Zone (R1), Akidograptus ascensus Zone (R2), Parakidograptus acuminatus Zone (R3), Cystograptus vesiculosus Zone (R4), Coronograptus cyphus Zone (R5), Demirastrites triangulatus Zone (R6), Lituigraptus convolutus Zone (R7), Stimulograptus sedgwickii Zone (R8), and Spirograptus guerichi Zone (R9).

Comparisons with the Longmaxi Formation (LM1–LM9) in the Yangtze region reveal that the nine graptolite zones of the Renheqiao Formation in the Baoshan Block correlate well with those of the Longmaxi Formation. This correlation not only strengthens the regional stratigraphic framework but also provides a solid basis for future shale gas exploration and assessment in the Baoshan Block.

The distribution of structural planes plays a significant role in determining the engineering and mechanical properties of rock masses. Accurately obtaining information of structural planes is crucial for analyzing the characteristics and stability of rock masses.

Three-dimensional point cloud data of a steep rock slope were acquired via 3D laser scanning technology. After filtering and preprocessing of the point cloud data, the open-source program Discontinuity Set Extractor (DSE) was then used to semiautomatically recognize and classify the point cloud data, obtaining key parameters and clustering information of the structural planes of rock slopes, such as attitude, trace length, and spacing. By fitting the point cloud clustering information, a probability distribution model was created, and a discrete fracture network (DFN) model was established. Furthermore, a three-dimensional block discrete element model of the steep slope was developed via the "Rhino-Griddle-3DEC" integrated modeling method, which is based on point cloud data. The model investigated the stability of the slope and potential failure areas.

Under gravity conditions, the safety factor of the entire slope is approximately 1.5, and the potentially unstable area is the dangerous rock mass located at the top of the slope.

Therefore, the structural plane parameters identified by this method can better reflect the engineering properties of the rock mass, providing important guidance for the analysis and evaluation of the stability of steep rock slopes.

Coal structure directly affects the pore and fracture system of coal reservoirs. Therefore, accurate identification of coal structure is crucial for guiding coal seam fracturing and coal bed methane extraction. Taking No. 8 coal of the Benxi Formation in the Yulin area of the Ordos Basin as an example, the coal structure is complex, necessitating the use of machine learning methods to address the nonlinear challenges in logging data interpretation.

In this study, Back Propagation Neural Network (BP), Random Forest, and XGBoost algorithms are trained on pre-processed core well data from the study area to perform coal structure inversion across the region. The analysis also considers the top and bottom plates of the coal seams and the coal thickness to explore the development of coal structure under tectonic control.

The results indicate that: (1) Random Forest and XGBoost algorithms provide more accurate inversion results than the BP neural network, aligning more closely with real core observations. (2) The degree of coal structure fragmentation in No. 8 coal in the Yulin area increases progressively from northwest to southeast. (3) Tectonic zones, developed from the central to southeastern part of the study area, cause a reduction in coal thickness, with the coal structure transitioning from primary coal to mylonitic coal under tectonic influences.

The study can provide valuable insights for coal structure identification and tectonic zone analysis in coalbed methane production.

Previous prospecting practices for deep-seated ore deposits utilizing organic hydrocarbons revealed significant differences in the metallogenic implications between deep-source superimposed anomalies observed in the deep margins of the Woxi and Wangu gold deposits and syngenetic superimposed anomalies identified in peripheral mineralized bodies. To further investigate the distinct mechanisms of Au-organic matter mineralization and halo formation between these two types,

this study focused on large-to-medium gold deposits (Woxi and Wangu) in the Xuefeng Uplift Belt and their peripheral mineralized bodies (exhibiting favorable shallow gold mineralization but poor deep mineralization). A comprehensive suite of analytical methods was employed, including Rock-Eval pyrolysis, chloroform asphalt "A" extraction and component separation, saturated hydrocarbon gas chromatography-mass spectrometry (GC-MS), fluid inclusion analysis, and C-H-O-S stable isotope tracing. Comparative investigations were conducted on their metallogenic geological characteristics, organic geochemical signatures, fluid inclusion properties, and isotopic geochemical features to elucidate the Au-organic matter mineralization and halo-forming mechanisms.

The results indicate that: (1) Large-to-medium gold deposits and peripheral mineralized bodies differ in metallogenic geological characteristics. The former underwent regional metamorphic hydrothermal filling-metasomatism followed by superimposed mineralization from deep-source fluids, while the latter experienced only regional metamorphic hydrothermal filling-metasomatism. (2) Both deposit types contain adsorbed organic matter derived from similar sources and paleo-depositional environments. However, total organic carbon (TOC) content in large-to-medium deposits exceeds that of peripheral mineralized bodies by over 50%, with oxygen and hydrocarbon indices being 10-fold lower and 3 to 8-fold lower, respectively, indicating higher organic matter abundance and maturity in large-to-medium deposits. (3) C-H-O-S stable isotope tracing demonstrates that metallogenic materials in large-to-medium deposits originated from the mantle, with ore-forming fluids derived from multi-stage evolutionary mixing of mantle-derived "deep-source fluids." In contrast, peripheral mineralized bodies sourced metallogenic materials solely from ore-bearing strata, with ore-forming fluids originating from shallow crustal "shallow-source fluids," reflecting differences in fluid dynamic and mixing mechanisms that led to distinct metallogenic implications. (4) The sources of organic matter in ore-forming fluids differ. Large-to-medium deposits exhibit superimposed "incremental" organic matter introduced by deep-source fluids alongside adsorbed organic matter, whereas peripheral mineralized bodies contain only adsorbed organic matter, explaining the significantly higher TOC in the former. (5) The Au-organic matter mineralization and halo-forming mechanisms diverge. In large-to-medium deposits, Au transported by mantle-derived fluids predominantly exists as organic complexes/chelates (e.g., Au(CH₃)²⁺, [Au(CH₂NH₂COO)]²⁺) via liquid-phase and gas-phase migration. In peripheral mineralized bodies, Au in shallow-source fluids primarily combines with organic matter through physical adsorption, lacking geochemical significance for organic complexation/chelation. This contrast manifests as stronger organic hydrocarbon anomalies and robust Au-organic hydrocarbon correlations in large-to-medium deposit carriers (ore bodies, overlying strata, or soils), versus weaker anomalies and poor correlations in peripheral mineralized bodies. These findings align with prior prospecting observations: "deep-source fluid mineralization-deep-derived metallogenic materials-strong Au-organic hydrocarbon correlations-deep-source superimposed anomalies-high deep prospecting potential" versus "shallow-source fluid mineralization-strata-limited metallogenic materials-weak Au-organic hydrocarbon correlations-syngenetic superimposed anomalies-limited deep prospecting potential."

This study provides novel insights and directions for evaluating deep prospecting potential in exploration geochemistry.

The surface structure and internal physical properties of geological bodies are simulated by using 3D geological modeling technology, which provides a reliable basis for revealing the spatial distribution of geological resources, resource estimation and resource development, and is the core technology of the construction of "glass earth". It is also an important carrier of geological time and space big data. Since the 1990 s, 3D geological modeling technology has been developed rapidly. Researchers proposed many different modeling methods, but there were still many problems in fine modeling of complex orebodies. Compared with the implicit modeling method, the explicit modeling method was more accurate in depicting small-scale geological structure features. However, for the large-scale fine 3D modeling of geological bodies such as complex vein orebodies, there were still some problems, such as low modeling accuracy and poor morphological expression of the model, so it is difficult to meet the needs of mine production and resource estimation at present.

In this paper, aiming at a series of complex geological phenomena of local vein orebody, such as bifurcation compound, non-ore skylight, rock entrapment, fault cutting and so on, the techniques of orebody split line, segmented modeling and orebody suture are comprehensively used to construct orebody split line, segmented modeling, orebody suture and so on. Four kinds of explicit 3D modeling methods of complex vein orebody, such as bifurcation composite orebody, non-ore skylight orebody, stone-bearing orebody and fault cutting orebody are studied systematically. Among them, the constraint point is generally located in the ore center and the outline of the orebody, and the complex part of the model needs to add constraint points to complete the constraint of the shape of the orebody. The splitting line is the connecting line between the cusp-out point at both ends of the boundary line of the orebody and the central point of the ore-seeing project. it is mainly used to split the complex vein orebody, and the split line is used to model the branch-bifurcated composite orebody according to the regional geological law. Segmented modeling is to model the complex parts of complex orebodies separately. The stitching of orebody is to assemble the segmented model along the strike to form a complete model.

Through the above technology and the explicit modeling method based on measured data, the high-precision and fast 3D modeling of complex vein orebody is realized, and the difficult problem of narrow, thin and complex vein orebody modeling is solved effectively. The 3D modeling process of different complex vein orebodies is improved, and the orebody model is displayed in 3D space in multi-angle, and the most real geological shape of the orebody is reconstructed with the outline of the orebody. High-precision model will not only obtain detailed 3D information of orebody, but also will grasp the distribution law of orebody quickly and accurately. This modeling method is of great significance to the fine 3D modeling of rare and precious metal and other complex vein orebodies, the estimation of mineral resources and the formulation of mineral resources development and utilization plan, and will better guide the exploration and prospecting work.

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 modelling 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.

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.

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

In this paper, the Firefly Algorithm (FA), Whale Optimization Algorithm (WOA) and Gray Wolf Optimization Algorithm (GWO) are combined with optimized Support Vector Regression (SVR), and based on which three hybrid swarm intelligent optimization prediction models are constructed to predict deformation of extruding surrounding rock tunnels. A database containing 62 samples was constructed, and seven initial parameters of tunnels and surrounding rocks were selected as the input parameters of the prediction models, and the radial deformation of tunnels as the output quantities. The coefficient of determination (R²), root-mean-square error (RMSE), and mean absolute error (MAE) were selected as the evaluation indexes of the model prediction effect. Finally, the effects of different input parameters on the prediction results of tunnel rock deformation were evaluated using normalized mutual information values.

The FA-SVR model demonstrated superior predictive performance during both the training and testing phases compared to the GWO-SVR and WOA-SVR models. For the training set, the corresponding R² values were 0.9634 and 0.9648, respectively, while the RMSE values were 18.786 and 14.699, and the MAE values were 9.460 and 11.170. The ranking of predictive capability was as follows: FA-SVR > WOA-SVR > GWO-SVR.

The results show that the firefly algorithm, the whale optimization algorithm and the 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 shows that joint frequency is the most important parameter that affects the predicted value of deformation of tunnel surrounding rock.

In order to study the dissolution damage and mechanical damage of carbonate rock by acidic filtration solution.

In this paper, through carrying out different flow conditions, different time length of phosphogypsum acidic leaching solution on the dissolution of limestone test research, analyze before and after the test of limestone specimens of the apparent characteristics, quality, porosity, uniaxial compressive strength, and acoustic emission counts and other indicators of the law of change, revealing the impact of the acidic leaching solution on the physical and mechanical properties of the carbonate rock.

The test results show that the dissolution rate and porosity increment of the rock samples are positively correlated with the dissolution time and the flow rate of filtration solution, and the mechanical strength is negatively correlated with the dissolution time and the flow rate of filtration solution. With the dissolution, the surface of the rock samples will be attached with thicker and thicker fluorite minerals, which makes the dissolution rate of the rock samples slower. The damage form of the uniaxial specimen gradually changed from shear damage to tensile damage. Under the acidic environment of phosphogypsum leachate dissolution, the internal mineral composition of limestone is dissolved, which causes changes in macro-mechanical parameters.

The research results can provide theoretical and experimental data for the stability analysis of karst media under the influence of acidic wastewater, acidic wastewater treatment, and tailing project safety design.

Seabed carbon dioxide (CO₂) geological sequestration technology has become a hot spot in carbon sequestration and carbon neutralization. There are favorable space and temperature and pressure conditions for the formation of CO₂ hydrate in the seabed sediments in the northern part of the South China Sea, and the formation of CO₂ hydrate in the cracks and pores can block the further upward migration of CO₂ and generate self-sealing capacity. However, the CO₂ leakage in the fracture and the effect of hydrate plugging and instability conditions are still unclear.

In this paper, the visualization experiment platform of hydrate growth and the instability process of water injection supercharging at high pressure and low temperature was used to observe the formation of CO₂ hydrate and experiment platform was used to simulate the conditions of seafloor sedimentary cover under the conditions of 2℃ and 3−4 MPa, and the hydrate instability condition and plugging effect were evaluated with the breakthrough pressure, breakthrough pressure difference, duration, permeability coefficient of initial instability stage and plugging rate as indicators.

The experimental results show that hydrate formation can be simplified into four processes: nucleation, expansion, forming and aggregation. Hydrate formed in cracks can efficiently block the migration of fluids such as water and CO₂, but the instability phenomenon begins when the fluid pressure gradually increases and reaches the critical breakthrough pressure. The instability process of hydrate can be simplified into two parts: particle size degradation and surface friction failure. The core of hydrate mass is unstable first, and the sealing state can be maintained before the surface of hydrate fails to friction fracture. The instability conditions of hydrate in the fracture are investigated experimentally. The breakthrough pressure is 6.414−6.966 MPa and the breakthrough pressure difference is 2.403−3.203 MPa. The instability rate of hydrate is mainly affected by the flow rate, followed by the saturation of hydrate, and the flow rate affects the instability rate through the interface effect. The key factors determining the breakthrough pressure of hydrate are temperature and pressure conditions, while the effect of flow rate is mainly reflected in regulating the specific time when hydrate enters the instability state. Under the condition of 3−4 MPa seafloor sedimentary cover, the sealing rate is 99.0%−99.6% and the permeability coefficient of initial instability stage is 0.555−1.260 md.

The experimental results provide a reference for the risk assessment of the overlying layer under similar conditions in the South China Sea for CO₂ seabed geological sequestration. The difference between the pressure under the capped CO₂ hydrate layer and the actual pressure on the seabed should be ensured to be less than 2 MPa to maintain the sealing effect of the hydrate.

Hot dry rock is a widely distributed and abundant geothermal resource, and its development and utilization are of great significance in reducing fossil energy consumption, alleviating environmental pollution, and ensuring energy security. Enhanced geothermal systems are currently the main way of developing hot dry rock resource, generally implemented through several links such as engineering site selection, geothermal drilling, thermal reservoir stimulation, flow test, and power generation engineering. Among them, flow test is an important link in undertaking thermal reservoir stimulation and power generation engineering, 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 test has the characteristics of long-term and complexity, 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, the flow test of hot dry rock development sites internationally is often intertwined with drilling and reservoir stimulation, and accompanied by scheme adjustments, in order to gradually achieve the power generation goal.

This article briefly summarizes the flow test experience and exploration direction of typical hot dry rock development EGS systems at home and abroad, elaborates on the influence of various factors on flow test, and proposes development suggestions based on the actual situation of the Qinghai Gonghe site. It can be seen that in the past, improving the effectiveness of flow test was mainly achieved through methods such as adjusting the development layer and well group, long-term circulation, hydraulic fracturing, and chemical stimulation. However, current technicians mainly explore by accurately obtaining engineering parameters and improving the design of well groups and reservoir stimulation processes.

In summary, the formulation of the flow test plan needs to fully consider geological factors and adapt to local conditions. At the same time, key technologies in flow test, 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 the numerical models with more accuracy , the improvement of 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 technology has advantages in thermal reservoir fracturing and energy enhancement in hot dry rock stimulation. Explosive fracturing technology has a certain effect on improving the complexity of near wellbore fractures and enhancing the injection capacity of well groups.Finally, with the goal of experimental power generation, focusing on key issues in multi well group flow test, improving the construction process of flow test is also an effective means to improve efficiency and save costs. With the increasingly mature development technology, hot dry rock geothermal resources will become an important part of China's energy structure, playing an important role in economic development and environmental protection.

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

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

The results reveal that the content of Nb₂O₅ in the claystone ranges from 41×10^-6 to 437×10^-6, with an average of 187.2×10^-6, which reaches the lowest industrial index of weathering crust type deposit, and the enrichment degree of Li, Ga and other elements is also high. The clay layer is rich in multiple critical metals and has significant ore-forming potential and prospecting prospect. Powder XRD analysis unveiled the abundant presence of anatase within the claystone in the study area. EPMA analysis revealed that the content of Nb₂O₅ within anatase varies from 0.09% to 3.40%, with an average of 1.17%.

According to the content of niobium in anatase, SEM-EDS scanning surface and the content of Nb₂O₅ in a whole rock sample, we believe that niobium within anatase primarily exists in the form of isomorphism, with a portion adsorbed by clay minerals. Niobium is mainly inherited from the weathering products of minerals such as sphene in the Emeishan basalt and the strength of weathering had an important influence on the enrichment and mineralization of niobium, which is a weathered-sedimentary deposit.

Studying the spatial distribution law of earthquake-induced landslides can not only provide an important basis for the investigation of hidden dangers of geological disasters in disaster areas, but also be of great significance for post-disaster reconstruction, post-disaster resettlement and site selection, and geological disaster prevention and control.

Taking the earthquake with M_s6.8 in Luding County, Ganzi, Sichuan Province on September 5, 2022 as an example, firstly, based on the optical image (DOM) with 0.2m resolution and the digital elevation model (DEM) with 0.5 m resolution obtained after the earthquake, the earthquake-induced landslides were interpreted by artificial visual three-dimensional remote sensing, and then combined with field investigation and correction, the final number of earthquake-induced landslides was determined. On this basis, the relationship between the geological background such as topography, geological structure and seismic factors and the distribution of earthquake-induced landslides was analyzed.

①The Luding earthquake event triggered 9248 landslides in the study area of about 680 km², mainly small and medium-sized landslides, and the highest area density of landslides was concentrated in the intersection of Xianshuihe fault, Daduhe fault and Jinping mountain fault. The total landslide area is about 45.57 km², and the average landslide area can reach 4941 m²; ②The distribution of landslides in this earthquake is mainly influenced by PGA and fault structures, and most of them are distributed within the range of PGA> 0.6g and 1km from both sides of the seismogenic fault; In addition, the development of landslide is negatively related to the distance from water system and road; Locally influenced by topographic factors, it mainly develops at the elevation of 1200-2400 m, the slope is 30-60, and the slope is eastward and southeast, and the stratum lithology is mostly hard rock; ③The relationship between the number and area of landslides and magnitude of Luding earthquake also follows exponential distribution; At the same time, due to the high accuracy of the basic data of this interpretation, the number of earthquake landslides obtained by interpretation is more than that of other documents, with a smaller minimum area and a larger total area.

The results obtained in this study have been applied to the post-disaster recovery and reconstruction in Luding earthquake-stricken area.

There are many factors affecting the bonding performance of the anchor-mortar interface, and the current research on the bonding performance of the interface focuses on the influence of a single factor, while the research on the bonding performance of the interface under the action of multiple factors still leaves a gap.

In this paper, we take the anchor-mortar as the research object, using electrochemical impedance spectroscopy to obtain the state of the anchor-mortar interface and electrochemical parameters under different influencing factors, obtain the bond strength of the anchor-mortar interface through the pullout test, and combines the electrochemical parameters to investigate the relationship between the electrochemical parameters and the pullout load when the specimen maintenance is completed and analyses the influence of the three factors on the bonding performance of the interface between the anchor-mortar.

The sensitivity analysis of orthogonal test shows that the pull-out load of the specimen is mainly controlled by the diameter of the anchor rod, the pore solution resistance (R_s) is mainly controlled by the water-cement ratio, and there is no obvious controlling factor for the charge transfer resistance (R_ct); at the early stage of specimen maintenance, under the influence of the three factors, there will be two kinds of states of the anchor-mortar interface, namely, complete passivation film and incomplete passivation film. The results of the study show that, within the range chosen for the test, the pullout load increases with the increase of fine sand particle size and the decrease of water-cement ratio, and the pullout load of the specimen is positively correlated with the pore solution resistance (R_s) and charge transfer resistance (R_ct).

The research results are of great significance for the validation of the effectiveness of anchored structural mortar proportioning and application.

Thermal structure analyses in the Songliao Basin are mostly confined to the sedimentary scale in the north-south zoning, and the lack of basin-wide thermal structure portrayal at the lithospheric scale constrains the genesis analysis in a geodynamic background.

Based on the published parameters of surface heat flow, geothermal gradient and thermophysical properties, this paper supplements the thermophysical properties of Yaojia Formation, Qingshankou Formation and Quantou Formation, and adds several geothermal field data to comprehensively characterize the geothermal field of the whole Songliao Basin, and analyze the characteristics of the present-day lithospheric thermal structure.

The results show that the geothermal gradient in Songliao Basin ranges from 21.10 to 63.45℃/km, with an average value of 41.41℃/km, which is higher than the global average value of 30℃/km; the distribution of surface heat flow values ranges from 30.38 to 106.58 mW/m², with an average value of 71.85 mW/m², which is higher than the global average value of 60 mW/m² and belongs to a typical "hot" basin. Under the influence of the Pacific plate subduction, the delamination and thermal erosion made the thinned thickness of the thermal lithosphere of 58.59 km. The heat flow contribution by radioactive elements in the thinned crust is only 16.40 mW/m², accounting for 22.83% of the surface heat flow; and under the influence of the dehydration of the stagnant plate, part of the molten mantle heat material is upwelled, the mantle heat flow contributes as high as 55.45 mW/m², accounting for 77.17% of the surface heat flow.

Therefore, controlled by lithospheric thinning and mantle upwelling, the Songliao Basin has "hot" basin properties and "hot mantle and cold crust" lithospheric thermal structure characteristics.

The seepage of fractured rock masses has non-uniformity and anisotropy, and its complexity is reflected in parameters such as density, orientation, and trace length of individual fractures, as well as the connectivity of fracture networks. The connectivity of fracture networks is a difficult problem in calculating the seepage parameters of three-dimensional fractured rock masses. At present, the calculation methods for seepage parameters of three-dimensional fractured rock masses have their own advantages and disadvantages due to different models. To analyze the hydraulic anisotropy and permeability coefficient of fractured rock masses, a new method for solving the permeability coefficient of three-dimensional fractured rock mass dense sections based on dimensionality reduction is proposed.

This method, founded on the simulation of three-dimensional fracture networks, approximates the fractured rock masses through dense sections in different directions, decomposing the three-dimensional fracture network into multiple continuous two-dimensional sectional fracture networks, using graph theory to analyze the hydraulic connectivity and permeability paths, and water head boundary conditions are set to calculate the permeability coefficient. Through the relationship between lines, surfaces, and volumes in space, the calculated permeability coefficient in two-dimensional space is expressed as the directionality in three-dimensional space, and the permeability tensor of the three-dimensional fractured rock mass network 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 solution formula for the equivalent permeability tensor of the rock mass. It also discusses the scale effect and the representation of anisotropy in the rock mass. By constructing three-dimensional and two-dimensional fracture networks, different sizes of unit cells were intercepted to calculate the permeability coefficient, and the side length of a typical unit cell was determined to be 20 m. The feasibility of the method was verified through field drilling water pressure experiments.

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

To enhance the efficiency of slope stability system calculations for multiple profiles, this study introduces a method based on spatial slope stability coefficient calculations. Initially, the two-dimensional residual thrust method is expanded to incorporate spatial profiles, resulting in the residual thrust method for spatial profiles.

Subsequently, the calculation process is further optimized by realizing the automatic generation and management of the profile on the 3D slope engineering geological model. To achieve swift and efficient calculation of slope stability coefficients, a method based on multi-threaded parallel computation is introduced. Combining this with the residual thrust method for spatial profiles allows for more precise and efficient computation of stability coefficients for multiple spatial profiles.

Using a specific 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. Seven spatial profiles are automatically generated and stability coefficients are calculated using multi-threaded parallel computation. Finally, we present visual results through visualization techniques.

The research findings suggest that adopting multi-threaded parallel computation for computing slope stability coefficients of multiple profiles can fully utilize computing resources and significantly improve computational efficiency. Furthermore, practical implementation of this method in engineering projects affirms its applicability and feasibility.

Carrying out land surveys and evaluations and developing special industries is a very important task for China to realize rural revitalization and consolidate the results of poverty alleviation. In order to more accurately and effectively guide regional agricultural production layout and specialty industry development, a selenium-rich land survey and evaluation was conducted in Tunliu District, Changzhi City, Shanxi Province, China.

Therefore, the indicators of selenium-rich industry quality, ecological environment and arable land strength were selected to construct a comprehensive quality evaluation system for selenium-rich land, and then fuzzy mathematical method, entropy weighting method, and composite index method were applied to evaluate and grade the land in the study area, and ArcGIS was used to implement the results.

The results show that: ① the land with soil selenium content grades of high selenium and moderate selenium in Tunliu District accounted for 54.47% of the statistical area, and these soils were concentrated in the eastern part of the district; the distribution of cultivated land strength grades in Tunliu District was uneven, and the overall characteristics showed that it was low in the western part and high in the eastern part; the results of the evaluation of ecological environment grades were clean in the whole district. ② There are 299.33 square kilometers of selenium-enriched land in Tunliu District with comprehensive quality grade of first class, accounting for 26.61% of the statistical area, and concentrating in the plain area in the east. ③ Wheat, sharp peppers and green peppers in Tunliu have reached the standard of selenium enrichment of crops. Among them, the selenium enrichment rate of sharp peppers is 100%. In addition, the results of heavy metal element testing show that the crops in the district are in good clean condition.

Based on the evaluation results of land and crops, and in conjunction with the spatial planning of land in Tunliu District, the land is divided into three types: A, B and C. Among them, type A land is characterized by high soil selenium content, rich nutrients and clean environment, so it is recommended to build selenium-enriched wheat and green vegetable planting bases in the area where this type of land is concentrated and develop tourism agriculture at the same time. Class C land is characterized by low soil selenium and nutrient content, which is unsuitable for planting crops, so it is recommended to build deep-processing factories for agricultural products in the areas where this type of land is concentrated, and to develop agricultural trade and tourism at the same time. It provides theoretical support and scientific suggestions for the planning of selenium-rich agriculture industry in Tunliu District and the synergistic development of the region.