In order to clarify the oil and gas exploration prospects in the middle and deep layers of Nanbaxian area in the northern margin of Qaidam basin and predict the distribution area of favorable reservoirs, this paper takes the Upper Member of Xiaganchaigou Formation in the Late Oligocene of Paleogene as the research object. Based on the comprehensive analysis of detailed core observation and drilling (logging) data, combined with the comprehensive analysis results of casting thin sections, clay mineral assemblages, chloride ion content of mudstone cuttings, porosity and permeability variation characteristics, the sedimentary environment of the Upper Member of Xiaganchaigou Formation in this area during the sedimentary period, the characteristics of clastic reservoir physical properties and their controlling factors were studied deeply. The results show that: (1) The sedimentary period of the Upper Member of the Xiaganchaigou Formation in the Nanbaxian area is the sedimentary environment of the braided river delta front. The lake water is mainly fresh-brackish, and the reservoir is mainly lithic feldspar sandstone and feldspar lithic sandstone. The compositional maturity of sandstone varies greatly and the structural maturity is low. The climate is dry and warm, and the clay mineral assemblage is dominated by illite and illite-montmorillonite mixed layer. The content of kaolinite and chlorite is low, and montmorillonite is absent. (2) The favorable reservoir of the Upper Member of Xiaganchaigou Formation in Nanbaxian area is the underwater distributary channel sand body and the mouth bar sand body of the braided river delta front in the Ⅳ-1-Ⅳ-4 sand group, with an average porosity of 16.3% and an average permeability of 37.4 × 10-3μm2. It is a medium porosity and low permeability reservoir and a medium porosity and medium permeability reservoir. The primary intergranular pore is the main pore type. Among them, the physical properties of the sand body of theⅣ-1-Ⅳ-4 sand group are better than those of the Ⅳ-5 sand group, and the physical properties of the underwater distributary channel sand body are better than those of the mouth bar sand body. (3) The controlling factors of reservoir physical properties in the Upper Member of Xiaganchaigou Formation in Nanbaxian area are mainly sedimentary facies and cementation, followed by compaction and dissolution. The high content of secondary calcite cement is the main reason for the poor reservoir physical properties of Ⅳ-5 sand group.

 A typical low resistivity reservoir is developed in the NgⅢ Formation (3rd Member of Neogene Guantao Formation) of C oilfield， Bohai Bay basin. Analyzing the influential factors of reservoir resistivity is of great significance to the efficient development. In this research， X-ray diffraction (XRD)， scanning electron microscopy （SEM）， blue-dye thin sections， and cation exchange capacity test (CEC) were used to quantitatively characterize the micro-features, including the clay mineral content and morphology， rock framework grain contact， and reservoir conductivity. The results showed that the content of smectite in clay minerals of the normal resistance reservoir is 23%-44%， while that of the low resistance reservoir is 39%-64%. According to the CEC experiments of reservoirs in different regions， the content of illite-smectite mixed layers is positively related to the cation exchange capacity. The smectite in the study area mainly exists in the form of illite-smectite mixed layers, and the illite-smectite mixed layers are distributed in two types. The first type is thin film， which wraps rock framework grains， leading to the formation of a conductive film on the surface of rock framework grains， this type accounts for about 80%; The second type exists between rock grains in flocculent and dispersed form， and accounts for about 20%， this type is relatively dispersed and fails to form a continuous conductive structure. Moreover， the low resistivity reservoir in the study area is mainly in Guantao Formation， according to the observation of blue-dye thin section, the rock framework grains are in point contact to line contact due to compaction, which leads to the contact of illite-smectite mixed layers conductive film on the surface of rock framework grains and the formation of continuous conductive structure. When illite-smectite mixed layers are in film shape and rock framework grains are in contact with each other, illite-smectite mixed layers can easily form a continuous conductive structure.

 In order to solve the problems of fault system development, formation fragmentation, rapid spatial variation of thickness, and difficulty in fine stratigraphic division and correlation in a certain area of western depression of Liaohe basin, the corresponding relationship between different stratigraphic fine divisions and correlation methods, such as traditional stratigraphic division and correlation methods. Vail classical sequence stratigraphy and high-resolution sequence stratigraphy, was determined first. On the basis of clarifying the sedimentary genetic model, the key wells are optimized, the stratigraphic subdivision scheme is determined, and the geological and geophysical information is fully excavated. The high-precision isochronous stratigraphic framework of single-layer level in the target layer of the study area is established by using the information of strong reflection of seismic event, lithology change of coring wells, sedimentary cycle, conductivity curve, resistivity curve value change, and fine secondary interpretation results of logging. The correctness of stratigraphic subdivision results is verified by using different single-layer top surface structure maps. The results show that the Yulou Oil-bearing sets in the study area can be divided into 29 short-term base level cycles (single layers), which correspond to the high resolution sequence stratigraphy and medium-term base level cycle(geological age 0.01 Ma). The band developed formation is generally in the direction of NE-SW, and the local highs are in a dome shape, mainly affected by sedimentation and differential compaction.

 Studying the characteristics and genetic mechanisms of structural fractures and predicting their distribution patterns are of great significance for guiding the exploration of volcanic gas reservoirs. This article focuses on the volcanic rocks of the Huoshiling Formation in Chaganhua subsag of Songliao basin. By comprehensively utilizing data of structural evolution, rock cores, imaging logging, rock physics experiments, and faults, the characteristics of structural fractures are analyzed to determine their formation periods. A three-dimensional geological model of the study area is established, and stress field simulation is carried out using the geostress module of Petrel software. The results show that structural fractures are mainly formed during the fault depression and inversion periods. Fractures formed during the fault depression period have high inclination angles and are mostly filled, they are mainly ineffective fractures. Fractures formed during the inversion period have low inclination angles and are partially filled, they are mainly effective fractures. Fractures formed during the inversion period cut through the fractures formed during the fault depression period. The maximum principal stress during the inversion period is horizontal principal stress, with a direction near east-west direction and a maximum stress value of 114.5 MPa. During the fault depression period, the maximum principal stress is vertical principal stress, with a direction near north-south direction. The stress field simulation results show that the current maximum horizontal principal stress direction is roughly east-west, consistent with the regional compressive stress direction. During the fault depression period, the maximum horizontal principal stress direction is roughly north-south, and the stress direction is basically consistent with the fault strike; The geostress is biased by the influence of faults. In areas with dense fault distribution, the stress direction is disorderly. In areas with sparse fault distribution, the stress direction is basically consistent with the principal stress direction. At the end of the fault, there is a clear phenomenon of stress concentration. It is concluded that effective fractures can be developed in areas with high maximum horizontal principal stress values, which can improve reservoir permeability. Therefore, drilling should be carried out in areas with high stress values and basically consistent stress directions.

 Grain size analysis is a very important method in the field of sedimentation. It is widely used in the evaluation of oil and gas reservoirs and the identification of sedimentary environment for terrigenous clastic rocks, but is rarely applied to endogenous clastic rocks such as phosphorus rocks. In this paper, the sedimentary phosphorite of Yangchang phosphate mine in Zhenxiong County, Yunnan province, is taken as the research object. The grain size information is obtained by measuring thin sections under the microscope, and the grain size distribution histogram, frequency curve, cumulative frequency curve, and probability cumulative curve are drawn and analyzed. The sedimentary environment of the study area is analyzed by using Cent-Median diagrams and structural parameter scatter diagrams. The research results indicate that grain size parameters are closely related to the hydrodynamic conditions of sedimentary water bodies. High energy hydrodynamic environments are prone to the formation of phosphate rocks with larger average grain size, poor sorting, bimodal and flat kurtosis. Low energy stable environments often form phosphate rocks with smaller average grain size, good sorting, single peak and sharp kurtosis. Based on various parameters and diagrams as well as the structural and texture characteristics, the grain size parameters of the sample exhibit the characteristics of beach sand. It is concluded that the Zhenxiong Yangchang phosphate mine was deposited in a shallow marine environment with continuous sea level oscillations and strong hydrodynamic forces.

 In recent years, large and medium-size uranium deposits such as Qianjiadian, Baolongshan and many uranium minings have been discovered through uranium exploration in the southern Songliao basin. Diabase is widely developed in the uranium ore concentration area, mainly distributed around the uranium deposit, near the oxidation fronts of Yaojia Formation, exhibits a spatial correlation with uranium mineralization. While the relationship between diabase and uranium mineralization remains debated, core observation, microscopic identification, and fluid inclusion analysis suggest a significant hydrothermal influence of diabase on uranium mineralization. The microscopic identification shows brannerite formed at a higher temperature and metasomatized the early ilmenite, filling along the fissures, and co-existing with automorphic pyrite, revealing that the formation of uranium deposits in southern Songliao basin may be superimposed on the factors of late magmatic hydrothermal activity. Fluid inclusion studies yield an average temperature of 115.7 ℃, characterizing the ore fluid as low-temperature hydrothermal, exceeding the temperature of uranium-containing oxygen-containing fluids (24.5  ℃) in Yaojia Formation oxidation zone. The inclusion salinity distribution shows low, medium, and high salinity areas (three intervels), representing three distinct fluid activity periods. Combining the existing chronology, geochemistry and exploration results, the uranium mineralization in the southern Songliao basin is divided into four stages: primary preconcentration (96.0-87.0 Ma), uranium-containing and oxygenated water infiltration mineralization (67.0-53.0 Ma), hydrothermal superimposition and reworking (43.0-37.0 Ma), and interlayer oxidation continuous superimposition (17.0-0.7 Ma). Notably, the  hydrothermal superimposition period (43.0-37.0 Ma) coincides with the major intrusion age (49.4-39.1 Ma) of diabase.

The Jinchang copper-gold deposit in Dongning Country, Heilongjiang Province, is a superlarge deposit in eastern Jilin-Heilongjiang, mainly developing three types of ore bodies: Cryptoexplosive breccia type, veinlet disseminated type, and fracture-filling type. Among them, the breccia type and veinlet disseminated type orebodies together consitutec a hydrothermal Cu-Au mineralization system with a shallow epithermal high-sulfidation type and a deep porphyry type. This paper focuses on the J-0 breccia type Cu-Au ore body, the J-1 breccia type Au ore body, and No.18 veinlet disseminated ore body. Through microthermometrry of fluid inclusions, laser Raman microprobe, rare gas isotope analysis, hydrogen-oxyen isotope analysis, with latest geochronological results, the properties, origin, and evolution of these ore-forming fluids in this copper-gold hydrothermal deposit are systematically studied. The underlying mantle-derived magma forms high-salinity, highly oxidizing Cu-rich metallogenic fluids through primary boiling. During the ascent process, these fluids undergo secondary boiling and react with the surrounding rocks, forming the J-0 breccia type copper-gold ore body in the shallow cryptovolcanic zone and the No. 18 disseminated veinlet type copper-gold ore body in the deep fracture filling zone. The addition of late atmospheric precipitation further promotes the precipitation of residual metallogenic elements. The magma chamber in the shallow crust directly exsolves high-salinity ore-bearing fluids. During the ascent of this fluid to the shallow crust and reaction with the surrounding rocks, the decrease in temperature and pressure leads to the precipitation of a large amount of gold and other metallogenic elements in the breccia and cement, forming the J-1 breccia type gold ore body.

 The Xin’antun molybdenum deposit in central Jilin Province, located within the Lesser Khingan-Zhangguangcai Range metallogenic belt, features simple stratigraphy with widespread distributed granodiorite, monzonitic granite and alkali granite in the southwest part of the mining area. During the early Yanshanian, frequent tectonic and magmatic activity, driven by the subduction of the Paleo-Pacific plate, facilitated molybdenum mineralization. The ore bodies, hosted in granodiorite and controlled by NE-trending faults, are mainly quartz veinlet-stockwork and veinlet-disseminated types, belonging to quartz vein-porphyry molybdenum deposit. To assess the prospecting potential comprehensively, this paper integrates geological characteristics with physical and chemical exploration data. Principal component analysis of soil geochemistry shows multi-stage metallogenesis from high temperature to medium-low temperature and indentifies a target area based on combined anomalies of Mo, W, Cu and Bi. Electric and magnetic surveys show magnetic anomalies correlating with distribution of the rock bodies and strata; Fault zones show positive and negative magnetic anomalies. Medium-high-resistivity and high-polarisation induced polarization anomalies delineate ore bodies and mineralised zones. Electrostatic bathymetry, combined with geological sections, confirms the shallow ore bodies are within a high-polarisation body, extending at depth, indicating potential for large-scale porphyry molybdenum ores. This comprehensive geological, physical and chemical exploration indentified 4 prospective metallogenic zones.

 The timing of lithospheric thinning and cratonic destruction in the Eastern North China craton (NCC) during the Mesozoic remains controversial. This study investigates the petrogenesis and tectonic environment of the Linjiagou pluton in the Liaodong Peninsula using petrology, zircon U-Pb dating, zircon Hf isotopes, and geochemistry. The Linjiagou pluton, composed primarily of medium-fine grained biotite-bearing monzogranite, formed at (220.8±1.2) Ma. Geochemically, the granite exhibits high SiO2(w(SiO2) = 69.24%-71.33%) and total alkali (w(Na2O+K2O)=8.37%-8.64%) contents, low MgO contents (w(MgO)=0.45%-0.60%), enrichment in large ion lithophile elements (e.g.,Rb,K,Ba,Th), depletion in high field-strength elements (e.g.,Ta,Nb,P,Ti), right-inclined REE patterns ((La/Yb)N average= 20.12), and negative Eu anomalies (δEu=0.38-0.46). Zircon Lu-Hf isotopes reveal negative εHf(t) values (-18.1 to -12.7), suggesting a parental magma source from partial melting of ancient crust. These geochemical characteristics suggest a within-plate post-orogenic extension environment, potentially related to the collision between the Yangtze craton and the North China craton. The widespread Late Triassic magmatism in the Liaodong Peninsula suggests that the decratonization of the NCC may have begun during this period.

 The Yanbian region of eastern Jilin Province, located on the southeastern margin of the Xingmeng orogenic belt and western Paleo-Pacific tectonic domain, provides a critical area for understanding their superposition and transformation. Dark microgranular enclaves within granitic rocks serve as valuable probes into deep Earth dynamics, recording crucial information on magma source characteristics and evolution. This study investigates Early Jurassic Yueshandong and Mingnandong granitic plutons in the Yanbian area, focusing on the genesis of the granitic rocks and their enclaves by petrogeochemical and zircon Lu-Hf isotope analyses to ascertain the tectonic background of Early Jurassic magmatism. The w(SiO2) of the dark enclaves in the Yueshandong pluton and the Mingnandong pluton are 51.09% to 53.52% and 49.53% to 51.96% respectively; The w(Cr) are 1 192.00×10-6 to 3 219.00×10-6 and 72.68×10-6 to 194.90×10-6 respectively; The w(Ni) are 330.60×10-6 to 693.20×10-6 and 58.61×10-6 to 81.06×10-6 respectively; The w(V) are 595.10×10-6 to 800.70×10-6 and 599.80×10-6 to 619.60×10-6 respectively; The w(SiO2) of the host rocks in the Mingnandong pluton is 65.75% to 68.19%, the w(Cr) is 33.20×10-6 to 57.54×10-6, the w(Ni) is 19.25×10-6 to 30.45×10-6, and the w(V) is 181.80×10-6 to 229.20×10-6. All the samples show the characteristics of being rich in sodium and poor in potassium, relatively enriched in light rare earth elements, relatively depleted in heavy rare earth elements, and being enriched in large ion lithophile elements (LILE) such as Rb, Th, U, and K, and relatively depleted in high field strength elements (HFSE) such as Nb, P, and Ti. The values of Nb/Ta and Rb/Sr are close to the mantle average values. The petrogeochemistry indicates that the magmatic source regions of the quartz diorite, granodiorite and their enclaves have mantle-source characteristics. The εHf(t) values of the zircons in the Yueshandong pluton are -3.2 to 2.4, with single-stage model age (TDM1) and two-stage model age (TDM2) of 1 004 to 746 Ma and 1 991 to 1 442 Ma, respectively, and its initial magma originated from the depleted mantle or the newly formed lower crust. The elliptical to circular shape and lack of baking rims of the dark microgranular enclaves, coupled with weak fractional crystallization trends, point to magma mixing. It is speculated that these dark enclaves in the Yueshandong and the Mingnandong plutons represent residues of the magma mixing process. The granitic magmatism in the study area during the Early Jurassic was likely formed in an active continental margin setting related to the subduction of the Paleo-Pacific plate.

The western Jilin is located in a transitional zone between agriculture and animal husbandry, characterized by arid climate, fragile ecology, and relatively lagging economic development. Investigating the relationship between land use transitions and ecological quality is crucial for sustainable utilization of land resources. This paper analyzes the characteristics of land use transitions and changes in habitat quality from 1990 to 2020 in western Jilin using ArcGIS and the InVEST model. By quantifying the contribution rate of habitat quality, it examines the impact of land transitions on habitat quality in this region. The results show that  land conversions were concentrated in cultivated land, grassland, and unused land. Specifically, cultivated land significantly increased to 54.72% of the total area by 2020, while grassland decreased annually, becoming the primary source for cultivated land expansion. Habitat quality in western Jilin experienced a process of initial improvement followed by decline, with habitat quality indices of 0.411, 0.423, 0.386, and 0.370 respectively, indicating overall low levels. The conversions between ecological lands, cultivated land, and unused land were the main drivers of habitat quality changes. Furthermore, the local spatial distribution of habitat quality in western Jilin shows a relatively clustered pattern with separately aggregated high and low-quality habitat areas, characterized by “large concentration, small dispersion.” This research provides insights into the complex dynamics of land use and ecological quality in ecologically fragile regions, offering valuable information for sustainable land management practices.

To investigate deformation mechanisms and surface settlement patterns of subway deep foundation pit retaining structures under composite geology, this study focuses on a metro station excavation in Changchun through integrated field monitoring and numerical modeling. The foundation pit is located in the terrace geomorphic unit of the alluvial valley. The excavation process of the foundation pit (bored pile with steel support, bored pile with anchor cable) was simulated by MIDAS GTS NX, a finite element simulation software. By comparing the field monitoring data with the numerical simulation results. The variation rules of horizontal displacement and surface settlement of two supporting forms of piles in composite stratum were analyzed.The results show that the horizontal displacement curve of the pile support section shows a “bow” shape with the increase of the depth of foundation pit, which is small at both ends and large in the middle. In the pile-anchor support section, the horizontal displacement of pile body shows a trend of approximate “funnel” shape with the change of foundation pit depth.As the distance from the monitoring point to the edge of the foundation pit increases, the surface settlement value presents a trend of increasing first and then decreasing, and the maximum value appears in the position within 3-5 m from the edge of the foundation pit. Reasonable setting of steel support axial force and anchor cable tension is beneficial to effectively control foundation pit deformation and surface settlement. The numerical simulation results are basically consistent with the change law reflected by the actual monitoring data, which verifies the rationality and reliability of the model. 

 The boundary layer fluid and its viscosity changeshave a significant impact on the flow of fluids in low permeability media. Existing low-velocity non-Darcy flow models usually ignore the change of fluid viscosity, or simply treat the fluid viscosity as a function of pore radius. The viscosity of boundary layer fluids is usually related to contact angle. In this paper, based on capillary model and fractal theory, a new low-velocity non-Darcy flow model is proposed considering the influence of contact angle on the viscosity of boundary layer fluid. The reliability of the model was verified through experiments and the sensitivity analysis of key parameters was conducted. The results show that the contact angle has a significant impact on the viscosity of the boundary layer fluid, which in turn affects the flow behavior of the fluid. After considering the change of fluid viscosity in the boundary layer, the flow velocity decreases. In this experiment, compared with ignoring the change of fluid viscosity, the decrease in flow velocity can reach 57.1%. The flow velocity decreases with the increase of fractal dimension of pore distribution (Df) and increases with the increase of contact angle. In this paper, under the same pressure gradient, when Df increases from 1.2 to 1.8, for every 0.2 increase, the flow velocity decreases by 18.4%, 23.3%, and 29.1%, respectively; When the contact angle increases from 0° to 80°, for every 20° increase, the flow velocity increases by 10.9%, 12.3%, 14.0%, and 16.3%, respectively. As the pressure gradient increases, the boundary layer fluid participates in the flow, and the effective seepage section and fluid effective viscosity increase. The increase of fluid viscosity has retarding effect on the flow, but the effect is smaller than the gain effect of the increase in flow section on the flow velocity. Therefore, in general, the flow velocity increases with the increase of the pressure gradient.

 Groundwater is the main source of production and living water for local rural residents in Chaoshan area，Guangdong Province. However, as a prominent groundwater environmental problem in recent years, the acidic shallow groundwater has had different degrees of impact on the health of residents and the balance of ecological environment. In this study, the groundwater drinking water source area in Fenghuang Town, Chao’an district was taken as the study area. The spatial and temporal distribution characteristics, hydrochemical types, characteristics and formation mechanism of pH value of acidic shallow groundwater in groundwater drinking water source area were analyzed by means of mathematical statistics and hydrochemistry. The results show that the groundwater in the study area has the characteristics of weak acidity and low total dissoloved solid （TDS）, and the hydrochemical types are mainly HCO3-Na type and HCO3-Na·Ca type. The rainfall in the study area is acidic as a whole, and there is no obvious pollution source related to pH change in the surrounding area. pH value is obviously affected by water-rock interaction and cation exchange. The weathering of silicate minerals and the dissolution of CO2 are the main sources of HCO3-. The dissolution and leaching of granite is the main source of H+. In summary, the acid shallow groundwater in the study area is mainly affected by acid rain leaching, leaching in aquifer media and cation exchange. In this study, through the analysis of the distribution characteristics and formation factors of acidic groundwater in the groundwater drinking water source area of Chaoshan area, it is of great significance to the rational utilization and development of shallow groundwater and the protection of groundwater resources.

 Land subsidence risk inducing factors are complex and spatial distribution varies greatly, in order to scientifically carry out land subsidence risk assessment, this paper proposes the raster information quantity method for the evaluation of land subsidence risk. Firstly, the information value between each rasterized evaluation index and surface variables is calculated to quantitatively characterize the strength of the association between the influencing factors and the risk of land subsidence; Then, an evaluation system with 11 indexes is constructed, including hazard, vulnerability, and exposure; Then, the subjective-objective comprehensive weighting method is used to determine the weights and calculate the risk value, and the risk evaluation is carried out through the reliability test of the working characteristic curve of the subjects; Finally, the above methods were applied to the risk evaluation of land subsidence in Cangzhou City, Hebei Province, in 2022. The results show that the raster informativeness values of the hazard and exposure evaluation indicators are high compared to the vulnerability evaluation indicators. Among the hazard evaluation indicators, the annual average land subsidence rate is a high-risk indicator, and when the annual average land subsidence rate is -127--17 mm/a, the informativeness value is 1.538, which is the most hazardous for the risk of land subsidence; Among the exposure evaluation indicators, the population density is a high-risk indicator, and when the population density is >5 430 people/km2, the informativeness value is 1.923, which is the most hazardous for the risk of land subsidence. At 1 km spatial resolution, the area proportions of land subsidence risk levels in Cangzhou City are distributed as follows: 9.90% high risk, 24.91% relatively high risk, 31.12% medium risk, 23.05% relatively low risk, and 11.02% low risk; The high-risk areas were mainly concentrated in the main urban area of Cangzhou City, Suning County, Huanghua City and other areas, and the medium-risk areas were mainly distributed in the western area of Cangzhou City; The reliability of the raster information quantity method to evaluate the risk of land subsidence in Cangzhou City is good, and the accuracy reaches 0.714.

 Greenhouse gas emissions have caused severe global climate change, and countries around the world are taking measures to mitigate the greenhouse effect caused by carbon emissions. Carbon dioxide capture and storage (CCS) is emerging as a large-scale greenhouse gas reduction technology and is gradually becoming one of the most important means of mitigating the greenhouse effect. There are a series of issues in the implementation of this technology, among which the geomechanical problems caused by injection and storage cannot be ignored. This paper reviews the impacts and risks caused by geomechanical problems due to injection and storage in CCS. The results indicate that CO2 injection triggers pore pressure variations, thermal stress, and coupling effect of chemistry and mechanics, leading to reduced reservoir rock strength, intensified deformation, and subsequent surface deformation. InSAR technology effectively monitors surface deformation, while site-specific microseismic monitoring reveals a direct correlation between injection rates and seismic activity. Controlling injection rates and pressures can significantly reduce the probability of caprock fracturing and fault reactivation. Furthermore, numerical simulation serves as a primary tool for assessing geomechanical risks at storage sites. Simulations demonstrate that selecting caprock with low-permeability and low-reactivity lithology minimizes leakage risks, and comprehensive evaluation of fault stress states is essential to avoid high-activity fault zones.

 Aiming at the deficiency that it is over subjective to determine index weights in the regional groundwater pollution risk assessment system, this paper takes Shallow groundwater in Baoding plain, Hebei Province as the study area, using random forest algorithm to construct the mapping relationship between groundwater pollution risk assessment indicators and nitrate concentration in order to optimize the weights of each index，and on this basis, the risk of groundwater nitrate pollution in shallow groundwater in Baoding plain is evaluated. The results show that when the number of decision trees is 130, the minimum sample number required for decision tree splitting is 82, and the maximum depth of decision trees is 2, the optimal weight is obtained. The results showed that the depth of groundwater level, types of vadose zone media, the net recharge rate of groundwater, and the ratio of cultivated land area account for larger weights, with weights of 5.00, 4.20, 4.14, and 3.40 respectively. The Spearman correlation coefficient between groundwater nitrate pollution risk assessment results and measured groundwater nitrate concentration has significantly increased based on random forest method, and the prediction accuracy was improved by 25.6%. 

 The propagation matrix theory considers the effects of transmission loss and inter-layer multiple waves on seismic responses. It provides the reflection coefficient spectrum for longitudinal and transverse waves in multi-layer media at arbitrary incident angles. This theory can yield higher accuracy in amplitude-versus-angle (AVA) multi-parameter inversion results than the Zoeppritz equations and their simplified versions. The inversion of the time-domain propagation matrix method requires a significant amount of memory because it involves computing the full-frequency Jacobian matrix. In contrast, frequency-domain inversion only focuses on specific frequencies, resulting in lower memory usage. The propagation matrix method effectively meets the requirements for frequency-domain inversion by solving the reflection coefficient spectrum in the frequency domain. This paper computes the gradient of the objective function in the frequency domain, and employs the L-BFGS (limited-memory Broyden-Fletcher-Goldfarb-Shanno) algorithm to accelerate inversion convergence. To validate the effectiveness of the frequency-domain propagation matrix method, we conduct inversions on both simulated and real data. The application of the propagation matrix seismic prestack inversion method in the frequency domain can stabilize the inversion of layer parameters. Compared to the results from the Zoeppritz equations, the frequency-domain propagation matrix inversion shows higher accuracy.

 Microseismic event recognition is a key part of the data processing of hydraulic fracturing microseismic monitoring, but there are some limitations in effective event feature extraction and noise resistance for current microseismic event recognition methods based on deep learning, which cannot meet the requirements of subsequent microseismic source localization and inversion. In this paper, a microseismic event recognition method based on an improved U-Net model is proposed. In this method, residual shrinkage modules are introduced during the downsampling process of U-Net. The residual blocks are used to implement shortcut connections of the network structure to reduce the loss of feature information during model training, and the soft thresholding shrinkage technology is combined to weaken the interference of noise features in microseismic data and enhance model noise resistance. The attention gate mechanism is introduced during the upsampling process to weight the extracted microseismic data feature vector by gating signal, so that the model focuses on the area of the data containing microseismic events, thereby improving the extraction ability and identification accuracy of the model’s effective feature. The experimental results of synthetic and actual microseismic data show that the proposed method can adequately extract the characteristics of effective microseismic events. Compared with the traditional convolutional neural networks and residual networks, it  can recognize microseismic events more accurately,  the accuracy of test datasets is improved by 6.28% and 3.70% respectively.   Especially for  the  recognition accuracy of  microseismic signals with weak energy,it is higher than that of similar network models. And it has better noise resistance and generalization ability.

 At present, deep learning-based fault recognition methods are emerging in an endless stream, focusing on the U-shaped network. However, the U-shaped network uses a large number of conventional convolutions, ignoring the problems of feature redundancy and over-fitting while improving the effect of feature extraction, resulting in high network complexity. In order to ensure the recognition effect and reduce the problem of feature redundancy, this paper proposes a lightweight fusion semantic segmentation network (LF-SeNet) for three-dimensional fault recognition. Compared with the traditional fault recognition network, LF-SeNet combines the idea of skip connection and feature fusion. The feature fusion module includes three-dimensional separable convolution, simple attention mechanism (SimAM), Dropout layer and finite matrix product operation, forming a lightweight feature fusion module. The effect of feature extraction is effectively guaranteed. In order to effectively reduce the complexity of the network, this paper combines the dilated convolution and the lightweight feature fusion module. On the one hand, it reduces the computational complexity of the network, and on the other hand, it reduces the feature redundancy problem caused by conventional convolution. In addition, this paper uses the Dropout layer and data enhancement method to improve the generalization ability of the network and alleviate the problem of overfitting. The method is tested on the FaultSeg3D dataset. The results show that the parameter amount of LF-SeNet is 2.56M, the number of floating-point operations is reduced by 95.59G, and the intersection-over-union ratio is increased by 2% compared with the traditional U-shaped network. Finally, this paper uses three-dimensional data synthesis technology to visualize the fault identification map. The experimental results show that the faults identified by LF-SeNet are continuous and clear, indicating that the network has better generalization ability, which proves the effectiveness of LF-SeNet in fault identification. 

 Due to the limitation of acquisition conditions and costs, the pre-stack seismic data may be irregularly distributed or incomplete in space, which  brings difficulties to the subsequent processing and interpretation of seismic data. In recent years, the convolution neural network method widely used in the reconstruction of missing seismic data lacks attention to the global information, while the network model with multiple downsampling brings low-frequency signal loss, and the reconstruction results of the low-amplitude missing part still need to be further improved. Therefore, this paper proposes a multi-scale feature self-attention model. A multi-scale wavelet fusion block based on the self-attention mechanism is designed at the bottleneck of the U-Net backbone network, and the outputs of all encoders are fused by discrete wavelet transform and self-attention mechanism, which effectively balances the global and local feature processing and reduces the signal loss caused by downsampling. A multi-scale receptive field is inserted into the network to improve performance and enhance spectral learning of different frequencies by learning multi-scale features for different degraded data. Compared with the classical reconstruction methods for seismic data, the reconstruction results of the algorithm in this paper are improved in both qualitative and quantitative assessments. On the synthetic dataset and the real dataset with 30% continuous missing  data,  the signal-to-noise ratios  of the reconstruction results   are 21.748 7  and 14.954 0 dB  respectively; On the synthetic dataset with 50% random missing and regular missing data, the signal-to-noise ratios of the reconstruction results are 28.832 0  and 37.724 2 dB  respectively.

 The accurate prediction of reservoir brittleness is of great significance for underground geotechnical engineering disaster warning and oil and gas extraction. A brittle intelligent prediction method is proposed based on the acoustic emission signals generated during rock compression and fracture. Four types of rocks with the same size but different brittleness were experimentally prepared for indoor uniaxial rock fracturing, and the collected fracture signals were preprocessed to create a sample dataset. To address issues such as insufficient training data and limitations of traditional data augmentation methods, an improved deep convolutional generative adversarial network (DCGAN) is proposed. A deep convolutional attention generative adversarial network model based on spectral normalization (CS-DCGAN) is designed to output high-quality time-frequency images of samples, enrich the original sample dataset, and serve as input for the residual network; Extracting, learning, and iteratively training effective information from images to establish an intelligent brittleness prediction model, and continuously adjusting the hyperparameters of the model to improve its prediction accuracy; Finally, a multi-criteria evaluation is performed. The experimental results show that compared with traditional DCGAN, the improved model generates higher sample quality, with a minimum Frechet inception distance (FID) of 67.96, which can alleviate overfitting and improve the performance of the residual network. The average recognition accuracy for different brittleness can reach up to 94.95%, proving the effectiveness of the proposed method.

 Urban road collapse is a serious safety issue in urban areas that can result in casualties and transportation disruptions, threatening urban operations and social development. Accurately predicting urban road collapse and analyzing its spatial and temporal dynamics are of great significance for urban safety. In this study, we focused on Futian District in Shenzhen City, Guangdong Province as the study area. We developed a model to predict the susceptibility of urban road collapse by integrating multi-source remote sensing data with the random forest algorithm. Additionally, we examined the primary indicators affecting the prediction performance of the model and the primary factors influencing the vulnerability of urban roads to collapse. The spatiotemporal prediction results of urban road collapse susceptibility show that the urban road collapse susceptibility prediction model, constructed by combining optical data and radar data, can predict the spatial and temporal changes of road collapse susceptibility  accurately. The predicted coefficient of determination is 0.65, indicating high prediction accuracy. From 2017 to 2022, the risk of roadway collapse in Futian District exhibited an overall increasing trend. There was a decrease in the area of zones with very low and low susceptibility, and an increase in the area of zones with medium and high susceptibility. The results of the random forest feature importance analysis indicate that the texture features extracted from image data make a significant contribution to the prediction model. Based on the geodetector results, it is known that population, GDP, and underground facilities are three key factors influencing urban roadway collapse.