The accurate identification of fluid properties is critical for reservoir evaluation.However,for the Paleogene low-porosity and low-permeability reservoirs in the Lufeng area,Pearl River Mouth Basin,the low contrast between oil and water layers in conventional logs due to the presence of high-resistivity water layers complicates the identification of oil and water layers.This study first ascertained the reservoir characteristics and genetic analysis of low-contrast oil layers.Then,it developed the Flair gas logging response equation and the Flair logging response correction method,aiming to overcome the challenge that gas logging response values of low-porosity and low-permeability reservoirs are significantly influenced by factors such as drilling rate and porosity.Given the differences in the properties and components of various fluids,this study constructed new oil-bearing and water-content indices using Flair gas logging curves.Moreover,this study characterized the geochemical chromatogram using a gamma probability distribution function and extracted the shape and scale factors to describe the chromatogram characteristics.Based on sensitivity parameters,this study plotted the characteristic parameter-based fluid property identification chart.The practical application shows that the log-based comprehensive fluid property identification method can yield satisfactory effects,achieving a compliance rate of 91.3%.Therefore,this method can be popularized.

The Fuling rock mass in southern Anhui Province, located in the eastern section of the Jiangnan uplift zone, is a complex granitic rock mass that has experienced multi-stage evolution. It primarily comprises two lithologies: Monzogranite and K-feldspar granite. By investigating the geological, petrographic, and petrogeochemical characteristics of the Fuling rock mass, this study delved into its evolutionary characteristics, genetic types, and tectonic environment, aiming to clarify its indication significance for rubidium enrichment. The results of this study are as follows: ① The geochemical characteristics of the Fuling rock mass demonstrate high SiO₂, Na₂O, K₂O, and Al₂O₃ contents, high w(K₂O)/w(Na₂O) ratios, and aluminum saturation indices (A/CNK) ranging from 0.95~1.08 (average: 0.99), suggesting high-K calc-alkaline quasi-aluminous to peraluminous granites; ② In terms of trace elements, the Fuling rock mass possesses high Li, Rb, Nd, and Ta contents and significantly low Sr and Ba contents, which may be associated with the fractional crystallization of feldspar; ③ The w(Nb)/w(Ta) ratios ranging from 5.71~10.94 (average: 8.41) and Mg^# values ranging from 0.02~0.31 (average: 0.13) indicate that the Fuling rock mass was primarily derived from the partial melting of lower crust rocks, suggesting A-type granites in a non-orogenic extensional environment; ④ The Rb content in the Fuling rock mass increases with the magmatic evolution degree. Compared to monzogranites, K-feldspar granites with a higher evolution degree display higher Rb content, implying that the Rb content in the Fuling rock mass is generally controlled by magmatic evolution. Overall, this study holds some reference significance for understanding the Yanshanian diagenesis and mineralization of southern Anhui Province.

This study conducted geochemical tests and analyses for vertical rock-soil profiles with different bedrock types in the Wenchuan section in the upper arid valley of the Minjiang River. Based on the above, this study explored the vertical distributions of elements in these weathering crust profiles to investigate the influence of bedrocks on the contents of chemical elements in soils. From a geological perspective, this study provided proposals for planting in agricultural production and eco-environmental restoration for the study area. The results of this study are as follows: (1) From top to bottom, weathering crust profiles can be divided into four layers: the humus layer (A), the illuvial layer (B), the soil parent material layer (C), and the bedrock layer (R). The humus layers exhibit higher average values of Al, Ca, K, Mg, Fe, Se, Zn, Cu, Cd, and Pb and lower average values of Si, Na, Mn, Cr, As, Cd, and Hg, compared to corresponding national average values in soils; (2) In weathering crust profiles with different bedrock types, except for elements with higher contents in both bedrocks and corresponding soil layers, the same elements manifest similar contents in other soil layers; (3) The chemical weathering intensity increased from the bedrock to the humus layers, with soil weathering degrees generally higher than bedrock weathering degrees; (4) In addition to characteristics inherited from soil parent materials, elements in weathering crust profiles show content differentiation, characterized by enriched Al, K, and Se in humus layers, enriched Na, Fe, Si, Pb, Cu, Zn, Mn, As, Cd, Cr, and Hg in illuvial layers, and enriched Mg and Ca in soil parent material layers.

Fine-scale characterization of reservoirs is critical for oil and gas exploration and production. Reservoirs in the Z gas field exhibit considerable burial depths and superposed sandstone and mudstone impedance characterized by dark spots, complicating their identification using conventional seismic methods. This study achieved the characterization of deep reservoirs in the Z gas field based on the dominant-channel stacking technique. First of all, this study analyzed the seismic response characteristics of deep reservoirs through forward modeling, positing that poor physical properties are the primary factor contributing to the formation of dark spots. Then, starting with the investigation of the near-well prestack gathers of the target layer, this study examined their amplitude variation with offset (AVO) characteristics and seismic phase stability at different angles, determining the dominant-angle seismic channels that can accurately reflect the phase stability of reservoirs. Finally, this study derived a lithology-sensitive 3D data volume through partial stacking of dominant-angle seismic channels, achieving the characterization of deep reservoirs. The near-trace superimposition (3°~15°) of phase-shift seismic data (-90°) allowed for effectively characterized the H3a reservoir in the Z gas field, providing a geophysical basis for subsequent well deployment. Therefore, the dominant-channel stacking technique can effectively characterize the spatial distribution of deep river-channel reservoirs, guiding the reservoir characterization of similar oil and gas fields.

Due to various strong electromagnetic mechanical interference and traffic barriers, many geophysical exploration techniques are ineffective in urban geophysical exploration.Based on transient surface waves,microtremor arrays,and microtremor spectral ratios,this study synthetically extracted two kinds of characteristic curves for joint inversion from the multi-source frequency-domain seismic data obtained by multi-point three-component low-frequency sensors.Consequently,this study achieved multi-source frequency-domain seismic exploration that integrated three techniques and developed the two-source synthetic dispersive spectrum extraction technique,the two-source characteristic curve joint inversion technique,and the equivalent homogeneous medium forward modeling technique based on inhomogeneous media.Engineering practice results demonstrate the improvements in the exploration accuracy and efficiency.

The Maokou Formationcarbonate reservoirs in the central Sichuan Basinexhibit well-developed dissolutionpores, vugs, and fractures, pronounced heterogeneity, and diverse types. This study aims to identify their types and establish the log-based identification criteria for various reservoir types. First, this study classified the reservoir types based on the analysis of casting thin sections, core photos, and micro-resistivity imaging logs.Moreover, it determined the conventional log response characteristics of different reservoir types. Finally, it conducted log-based identification of reservoir types using the fracture porosity (φ_f) -secondary porosity index (R_P) cross-plotting method. The results are as follows: (1)The Maokou Formation carbonate reservoirs in the central Sichuan Basin can beclassified into four types, i.e., fractured-vuggy, fractured-porous, porous-vuggy, and matrix porous reservoirs;(2) Fracture porosities calculated from different models are more similar in the case of more developed fractures, and dissolution pores and vugscan affect the fracture porositycalculation results to some extent;(3) The φ_f-R_P cross-plotting method can effectively identify reservoir types. These research results provide technical support for the log-based identification of carbonate reservoir types.

There exists a continued debate concerning the spatial distribution and deep structural characteristics of the Yagan fault zone in northeastern Ejina Banner, Inner Mongolia. Adhering to the known-to-unknown research approach, this study completed five magnetotelluric sounding (MT) profiles. First, it delved into the relationship between the electrical structure characteristics of a MT profile (MT01) on the west side of the study area and the geological structure information of the Yagan fault zone within the profile. In terms of electrical characteristics, the Yagan fault zone was determined as a resistivity gradient zone characterized by northward dip, high dip angles, and deep depths. Based on these characteristics, and combined with the inversion interpretation results of four MT profiles (MT02~MT05) on the east side, this study identified the deep positions and structural characteristics of the Yagan fault zone within all the MT profiles. Moreover, it determined the major electrical directions of all the MT profiles using the impedance tensor decomposition technique, and the spatial trend of the Yagan fault zone based on the two-dimensional inversion interpretation results. As revealed by the results, the Yagan fault zone within the study area exhibits an overall nearly EW strike at the shallow surface and a strike of NE45° in the deep part, with an average width of approximately 6.8 km. It is a reverse fault with a gradual arc deflection to the north from west to east, manifesting a generally northward dip direction, dip angles ranging from 60° to 67°, and a fault depth of about 20 km. The obtained deep electrical structure model effectively reveals the deep structural characteristics of the study area. providing certain reference significance for the study of regional tectonic evolution

Huize County of Yunnan Province is situated in the karst area in southwestern China, where karst groundwater is its primary water source. To conquer local difficulties in drinking water, this study constructed a conceptual model of groundwater occurrence by fully investigating the hydrogeological conditions of the Huize area. Moreover, this study evaluated the applicability and optimal combination of geophysical methods based on the measurement results of petrophysical properties. According to the actual local needs, this study deployed a comprehensive profile combining high-density electrical resistivity tomography (HDERT) and audio magnetotellurics (AMT) in Tuogu Village, Huize County. The groundwater enrichment site was delineated relying on resistivity anomalies, effectively guiding the layout of boreholes. The boreholes achieved the maximum single-borehole water yield of 20.76 m³/d, thus effectively alleviating the local drinking water problem. The HDERT-AMT combined exploration method proves to be optimal for prospecting for groundwater in carbonate rock areas. HDERT can accurately characterize weathered layer thicknesses, bedrock boundaries, fissure evolutionary degrees, and water-bearing properties of strata, constraining groundwater recharge channels, thus counteracting AMT's defects for identification of near-surface stratigraphic structures. AMT can accurately reflect the spatial structures of fracture zones and the macrostructures of strata, limiting the boundary conditions (aquicludes) of water-bearing structures, thus making up for the defects of insufficient detection depths of HDERT in high-resistivity stratigraphic regions. HDERT and AMT, which are complementary to each other in terms of accuracy and depth, can be applied to identify and constrain the spatial occurrence conditions of groundwater migration, storage, and enrichment.

The Ximeng-Lancang area in southwestern Yunnan resides in the southern section of the Nujiang-Lancangjiang-Jinshajiang orogenic belt in Southwest China. The 1∶50,000 geochemical soil survey revealed 24 rare-earth-element (REE) geochemical anomalies, which are primarily distributed in the Carboniferous Pingzhang Formation mafic volcanic rocks and the Carboniferous-Permian Yutangzhai Formation sedimentary carbonate rocks within and near the Changning-Menglian deep fault zone. Furthermore, the AP00 REE geochemical anomalies ranking high in the evaluation were analyzed in detail through a 1∶10,000 geochemical soil survey, a 1∶10,000 special geological survey, and light-duty prospecting engineering in mountainous areas. A new type of REE ores in weathering crusts has been first discovered in sedimentary carbonate strata, with preliminarily estimated REE resources reaching a medium scale, suggesting a prospecting breakthrough. This finding shows a new prospecting approach, which can be referenced for similar research. As revealed by a comprehensive analysis of the regional geological and geochemical settings and the data of AP00 REE anomalies, the AP00 REE ores in weathering crusts have undergone a gradual enrichment and mineralization process involving four different geological processes, suggesting polygenetic compound REE ores. Considering the low leaching efficiency of AP00 REE ores and significant structural (magmatic) superimposed mineralization of the heavy REE yttrium, it is inferred that yttrium-dominated primary REE ores might exist in the deep part, implying high potential for heavy-REE ores.

Surface water resources are scarce in Ritu County of the Ali area due to the absence of large rivers. The strata in the area are primarily composed of Jurassic and Cretaceous sedimentary rocks, exhibiting significantly varying spatial water abundance, thus posing challenges in water exploration through drilling. Based on hydrogeological survey data, this study summarized the occurrence patterns of pore water in Quaternary unconsolidated rocks and fissure water in fault structures and the electrical characteristics of aquifers in the area. It explored the structural fissure water with high water abundance in the area using the high-density resistivity method and the audio magnetotelluric method. Based on the geophysical exploration results, it delineated favorable aquifers. Furthermore, it verified the exploration accuracy through drilling, obtaining high-yield water wells, and ensuring the supply of drinking water. Therefore, the combination of multiple geophysical exploration methods is effective in groundwater resource surveys, improving the exploration accuracy of groundwater resources and providing effective technical support for well deployment.

The development of gold deposits in the Liaodong region is considered to be controlled by the superimposed detachment fault zone of the metamorphic core complex system. The traditional view holds that the thickness of the cap rocks of the Yongning Formation in the Yongning Basin can exceed thousands of meters, thus hindering the migration of ore-bearing fluids and the formation of large-scale metal deposits. The exploration of deposits in the Liaodong region has remained within a depth of 1 km due to limited exploration efforts and insufficient research. This study obtained the resistivity distribution characteristics within a depth of 3 km in the Zhengtun area using the wide-field electromagnetic method (WFEM), ascertaining that the thickness of the cap rocks in the Liaodong region is around 1 km, in sharp contrast to the extremely thick cap rocks in the Yongning Formation. As verified by the 2 km deep drilling, an unconformable contact between the Yongning Formation and the underlying Archean basement was observed at a hole depth of 1 345 m, without significant structural detachment near the boundary. This study demonstrates that the thickness of the cap rocks in the Yongning Basin is merely around 1 km. Considering multistage active fault structures and densely distributed hypabyssal rock vein swarms in the area, it is preliminarily determined that the geological setting for mineralization in the Yongning Basin is akin to that of the Jiaodong gold ore concentration area. The ore-bearing metamorphic fluids or magmatic-hydrothermal fluids might have migrated to the upper part of the boundary for mineralization during the destruction of the North China craton. Overall, the Liaodong region has the potential to achieve breakthroughs in polymetallic prospecting, and the WFEM pinpoints the deep mineralization prediction.

This study conducted SKS shear-wave splitting measurements of 39 distant earthquakes with magnitudes above 5.8 and epicentral distances between 88° and 120° recorded by the monitoring stations of China Earthquake Networks Center in the Qinghai-Tibet region in the past five years. Based on these measurements, this study investigated the anisotropic and deformation characteristics of Tibetan Plateau and its surrounding areas. Within the Qinghai-Tibet region, the fast axis of SKS shear-wave splitting measurements from west to east gradually shifted from NE-SW to E-W and then to NNW, roughly aligning with the direction of the GPS velocity field and changing in a clockwise direction. The reason for the measurement results in this region lies in that the westward retreating of the Burma plate during the eastward subduction may have caused circular deformation in the local lithosphere. The GPS data of the southern Sichuan-Yunnan region reveal nearly ES-directed surface deformation and NW-SE-trending strike-slip faults, with the fast-axis direction of the Pms wave for crustal anisotropy being S-N or NNE-SSW. The SKS splitting measurement results of this study reveal the E-W-directed anisotropy of the upper mantle, which intersects at a high angle with or is perpendicular to the fast-axis direction of the Pms wave. This suggests that the mantle flow field of the deep asthenosphere in Yunnan is inconsistent with the deformation characteristics of the crust and surface, and the mantle and crust show distinct deformation mechanisms and anisotropy sources, resulting in decoupling deformation.

The goaf and subsidence areas formed ue to the mining of subsurface coal seams can cause damage to surrounding ecological environments.At present, the detection effects of double-layer goafs in coal mines, especially the second-layer goafs, are unsatisfactory. In response to this challenge, this study delineated goafs using apparent resistivity and impedance phase derived from the data acquired by an efficient controllable source audio-frequency magnetotelluric instrument. In the case of a shallow water-bearing goaf with low resistivity, the apparent resistivity displays shadow effects, leading to an extended abnormal range of the upper target, which is unfavorable to the identification of the lower high-resistivity goaf. In contrast, the impedance phase, exhibiting minor shadow and static effects, shows a significant response to the lower goaf. As indicated by the theoretical model testing results, the combination of apparent resistivity and impedance phase can effectively determine shallow water-bearing goafs and deep unfilled high-resistivity goafs. This combination method was employed to interpret the double-layer goaf in the Shenfu mining area of the Jurassic coal field in northern Shaanxi, achieving satisfactory results through the mutual verification of the two parameters. Engineering verification results indicate that this method demonstrates reliable inference and expected exploration effects. Overall, this method provides a new approach for CSAMT-based inference and interpretation in the exploration of double-layer goafs in coal mines, thus holding critical technical promotion and reference significance.

Given the low resolution and poor wavelet coherence of seismic data for the loess tableland area of the Ordos Basin, this study proposed a method for calculating the near-surface Q-value model for near-surface Q-absorption compensation of seismic data. Investigations reveal that micrologs have been used to obtain the Q field of a whole survey area by calculating the Q value and subsequent interpolation. Based on previous research results, this study calculated the Q values of well sites and near-surface velocity values using dual-well micrologs. Then, the regional relationship function between near-surface velocity and Q was determined through fitting using the least squares method. Furthermore, the near-surface Q field of the study area was obtained using the near-surface velocity field derived from the tomographic inversion of the first arrival wave post basic static correction. Consequently, the near-surface Q field of the whole survey area were calculated from the Q values of microlog positions, and the near-surface Q absorption compensation of prestack gathers was achieved. As indicated by the application of the study area’s seismic data, which are characterized by complex surface and subsurface conditions, the inversion of the Q field for near-surface Q absorption compensation using the method proposed in this study can effectively enhance the wavelet coherence of seismic data, broaden the frequency band, improve the log-seismic matching relationship, and eliminate the influence of near surface on seismic wavelets.

Due to the multiplicity of solutions and the multiple extrema of the inversion objection functions,conventional nonlinear optimization algorithms are susceptible to unstable convergence and local optimum in the inversion of Rayleigh wave dispersion curves.This study improved the standard butterfly optimization algorithm by incorporating dynamic switch probability and nonlinear self-adaptive weight factors,yielding an elevated global exploration capacity in the early stage and a high local research ability in the latter stage.Furthermore,the dimension-by-dimension Cauchy mutation,along with a greedy algorithm,was employed to update the current best position during each iteration,ultimately directing the whole swarm population toward the global optimum.Tests of four commonly used benchmark functions demonstrate that the improved butterfly optimization algorithm(IBOA) outperformed other nonlinear algorithms,including the genetic algorithm and particle swarm optimization algorithm,in terms of the global research capacity of both unimodal and multimodal functions.Different algorithms were adopted for the inversion of the dispersion curves of three theoretical geological models.The results show that IBOA yielded inversion results that were closer to the models even when the dispersion curves contained 10% random noise.Finally,the IBOA was applied to actual Rayleigh wave data,and the inversion results were highly consistent with the strata revealed by drilling.Compared with the genetic algorithm and the particle swarm optimization algorithm,the IBOA significantly improved the convergence speed,as well as solution accuracy and stability.Therefore,the IBOA has a certain practical value and application prospects.

Controlled source radio-magnetotellurics (CSRMT) measurements typically use artificial field sources transmitting at frequencies ranging from 1 to 1 000 kHz. Among the many transmitting sources of the artificial source electromagnetic method, the orthogonal horizontal electric dipole source and the orthogonal horizontal magnetic dipole source are preferred field sources for tensor resistivity measurements. Hence, using the analytical formulas for electromagnetic fields based on the horizontal electric dipole source and the horizontal magnetic dipole source, this study calculated the electromagnetic fields based on the orthogonal horizontal electric dipole source and the orthogonal horizontal magnetic dipole source in the homogeneous half-space model. The results show that: (1) The displacement current needs to be considered at transmitting frequencies above 100 kHz; (2) The effects of displacement current on the tensor apparent resistivity and the impedance phase can be ignored in the far zone; (3) With a constant model resistivity and varying distances between transmitter and receiver, model calculations indicate a larger measurement range in the far zone of the high-frequency electromagnetic field; (4) With a constant distance between transmitter and receiver and varying model resistivities, model calculations suggest that the far-zone range of the electromagnetic field is significantly influenced by resistivity, and that the high-resistivity model requires higher frequencies for achieving far-zone observation conditions.Compared with the electric dipole source, the magnetic dipole source exhibits smaller deviations on the tensor apparent resistivity and impedance phase with the actual value, which is more suitable for geological analysis.

Research on shear-wave prediction for complex lithologic assemblages of the Permian Fengcheng Formation in the Mahu sag is critical but challenging for accurately identifying hydrocarbon accumulation zones in the sag.The key to the prediction is to make breakthroughs in petrophysical modeling based on different lithologies.Given various lithologic types and intricate mineral compositions,this study delved into petrophysical modeling based on different lithologies.Consequently,this study developed an interval-,lithology-,and model-specific shear-wave prediction technique for complex lithologies.Furthermore,it established a technique for building a dry rock matrix for alkali lake-type dolomitized tight reservoirs by highlighting the major rock mineral compositions and merging the same types of rock mineral compositions.Additionally,the self-consistent model was selected for shear-wave calculation in the petrophysical modeling of dolomitized sandstone reservoirs.These techniques have been applied in the Fengcheng Formation of the Mahu Sag,achieving encouraging application results in both the shear-wave prediction of complex lithologic assemblages and the prediction of sweet spots.This study will provide a basis for well deployment and reserves determination in the area and offer valuable experience for oil and gas exploration in similar areas.

Establishing a spatial prediction model for soil organic matter (SOM) can accurately predict the spatial distribution of SOM content, playing a significant role in scientific soil management and ecosystem service enhancement. Focusing on the soils in Yonghe County, Linfen City, Shanxi Province, this study extracted topographic factors and vegetation indices from the digital elevation model (DEM) and vegetation remote sensing data. With soil attributes as variable factors, this study, using the Boruta algorithm, selected the characteristic variablescorrelating strongly with SOM from variable factors as auxiliary variables. These auxiliary variables were used as model inputand the measured SOM values as model output.The SOM content in samples in the training set was predicted usingthe ordinary Kriging (OK)method, the back propagation neural network (BPNN), the genetic algorithm-optimized BPNN (GA-BPNN), and the improved BPNN combined with the geostatistical method (the GA-BPNN-OK method) separately. The prediction accuracy was comparatively analyzed based on samples in the validation set. The results show that: (1)The Boruta algorithm ranked the selected characteristic variables in order of importance, obtaining the sequence of total nitrogen >topographic wetness index (TWI) > elevation > slope > normalized difference vegetation index (NDVI) > enhanced vegetation index (EVI); (2)Despite local differences,the SOM prediction results obtained using the four methods exhibited roughly the same overall spatial distribution: low in the western and southwestern portions of the study areabut high in the eastern and southeastern portions;(3)Compared to the other three models, the GA-BPNN-OK model demonstrated more distinct low- and high-value areas in the predicted SOM distribution. (4) As revealed by the comparison of prediction accuracy indices, the GA-BPNN-OK method yielded a minimum root mean square error (RMSE) of 0.059, a minimum mean absolute error (MAE) of 0.240,a minimum mean relative error (MRE) of 0.165, and a maximum fitting coefficient (R²) of 0.78. To verify the effects of the Boruta algorithm in improving model accuracy, global variables, as well as the variables determined through characteristic selection, were used as the model inputof the GA-BPNN method. The comparison of the prediction results indicates that the Boruta algorithm reduced the model error. Therefore, the Boruta algorithm and the GA-BPNN-OK method constitute the optimal prediction model for the spatial distribution of SOM content.

Magnetotelluric (MT) sounding is a vital exploration method in tunnel engineering. Inversion methods can assist geologists in interpreting geological data by converting MT data into geoelectric parameters. However, conventional inversion methods exhibit inferior timeliness and reliance on initial model settings. In this study, deep learning was applied to the one-dimensional inversion of magnetotelluric data. First, an improved DenseNet model was constructed and trained to invert geological models of various resistivity-variable strata, yielding a fast computational speed and high accuracy. Then, the robustness of the improved DenseNet model was tested, suggesting that its network structure can achieve satisfactory inversion results for noisy data. Finally, this artificial intelligence technique was applied to the MT data inversion of the Hongjiaqian tunnel in the Huangshan area, obtaining geophysical exploration results that match the geological research results. Additionally, relevant construction recommendations were given based on the inversion results.

The fault-controlled carbonate area in the northern depression of the Tarim Basin possesses abundant oil and gas resources.Identifying the oil-water contact (OWC) of fault-controlled tabular reservoirs is critical for their effective exploitation.However,OWC identification through drilling is costly and challenging.In contrast,it is efficient to identify the OWC using geophysical methods.This study proposed a time-frequency analysis method based on generalized S-transform.As revealed by the joint analysis of extensive time-frequency analysis results of through-well seismic channels and production performance analysis data,the depth/time-varying main frequency of seismic data is positively correlated with the oil layer thickness.Hence,this study proposed to identify the OWC using the abnormal inflection point of the energy envelope of seismic channel time-frequency gather.Experimental results demonstrate that oil layer thickness results obtained are uncertain,generally reliable,and reliable in the case of oil column height (OCH)<120 m,120 m≤OCH≤250 m,and OCH≥250 m,respectively.The method proposed in this study was applied to a fault fracture zone of an area of the Fuman oilfield,obtaining the main predicted oil layer thicknesses between 200 m and 520 m,aligning with the actual exploitation results.Therefore,the method of this study can be employed to guide exploitation.

To explore the critical factors influencing the results of microtremor-based exploration at a depth of thousands of meters,this study conducted experiments using triangular arrays based on spatial autocorrelation(SPAC) and extended SPAC(ESPAC).Focusing on factors such as array size,acquisition unit frequency,and acquisition duration,this study explored the frequency band ranges corresponding to different array sizes,the arrangement of arrays in kilometer-depth exploration for obtaining both deep and shallow data,and the improvement in deep resolution.Based on the analysis and discussion results,this study established a parameter-setting system to improve the accuracy of exploration at a depth of thousands of meters.

For the high-density resistivity method, favorable grounding conditions are required to ensure the establishment and measurement of the geoelectric field. Otherwise, unfavorable grounding conditions, like rigid pavement, will prevent some electrodes from being inserted into the ground, leading to the loss of valid data from standard observation devices and reducing the imaging quality. Therefore, this study proposed a method for the fast observation device design. This method supplemented data using an asymmetric quadrupole electrode array according to the spatial positions of missing data's recording points. Numerical simulations show that the method proposed in this study significantly improved the imaging effects of Wenner, Schlumberger, and dipole-dipole arrays, with a second-scale design time. In this study, an observation device based on asymmetric design for high-density resistivity imaging was successfully applied to the embankment detection in Ningbo, reducing the influence of motor lanes on data quality and accurately locating the embankment position.

The low-amplitude structures on the top of the Carboniferous carbonate rocks in the Akzor area on the eastern margin of the Pre-Caspian Basin show considerable potential for oil and gas exploration.However,the complex distribution of overlying Lower Permian strata and significant changes in lateral velocities pose high challenges for the mapping of the Carboniferous low-amplitude structures.To achieve the rapid mapping of the structures in the study area,this study selected the frequency-division interval velocity inversion method to build the velocity model for the study area after comparing three methods for velocity modeling.The velocity model built in this study,solving the problem that the frequency-division interval velocity inversion is constrained by the lateral continuity of conventional interval velocity inversion methods,yielded more accurate velocity characterization of anomalies in the Lower Permian carbonate rocks.Moreover,compared to the collaborative velocity modeling method based on well-seismic velocity spectra and the conventional interval velocity inversion method constrained by log data,the frequency-division interval velocity inversion method effectively improved the depth-domain mapping accuracy of the underlying Carboniferous low-amplitude structures in the study area,boasting high performance.

Data integration based on MapGIS includes data conversion, data normalization, data fusion, and related research. A synthesis of existing research suggests that data conversion has been intensively studied, while there is a lack in studies of data normalization and data fusion. This study improved the data normalization method based on the complex and extensively applied geological maps, achieving the normalized annotation and color filling for thousands of geobodies at one time. A technical process for data fusion was established by analyzing the applicable conditions of various commonly used methods for data fusion and making some supplementation. Besides, ASCII code files were prepared for mapping small coal pillars in batches. The results of this study show that improving the data normalization method, establishing the technical process for data fusion, and making full use of ASCII code files can significantly enhance the efficiency of data integration and broaden the mind for problem solving.

The semi-airborne transient electromagnetic (SATEM) noise data, exhibiting intricate forms, high acquisition costs, and small volumes, cannot be augmented using conventional augmentation methods, thus significantly hindering the subsequent denoising work. Hence, this study proposed a data augmentation method for SATEM signals based on the generative adversarial network (GAN). By designing the generator as a long short-term memory (LSTM) network and training the generator and discriminator models based on the dataset of real-measured SATEM noise, this study obtained a generator model that can generate simulated noise data. Then, this study analyzed the distributions of the simulated noise generated by the generator and the real-measured noise. Moreover, this study compared the performance of the denoising network before and after augmentation, demonstrating the effectiveness of this method for augmenting real-measured SATEM noise data.

Heavy metal pollution in soils has become increasingly prominent. To explore the distributions of heavy metals in soils in Fangshan District, Beijing, China, this study collected 152 topsoil samples and 240 deep soil samples from this district. Based on these samples, this study statistically analyzed the distributions and enrichment factors (EF) of seven heavy metal elements, namely As, Cd, Cr, Cu, Hg, Ni, and Pb. Furthermore, this study investigated the correlations, sources, and contribution rates of these elements through principal component analysis (PCA) and positive matrix factorization (PMF). The results show that: ① Elements As, Cd, Cu, Ni, and Pb exhibit high contents in the topsoil of the Shidu, Shijiaying, Xiayunling, and Puwa areas. Besides, elements Cr, Ni, and As manifest high contents locally in Zhoukoudian, Nanjiao, and Hebei Town. Element Hg displays high content in the eastern plain areas including Doudian, Yancun, and Changyang; ② Elements Hg and Cd are highly enriched, and there exist strong corrections among elements As, Cr, and Ni; ③ These elements primarily originate from natural sources (soil parent materials), which contribute to 73.6% to 78.6% of the elements. Element Cd is mostly sourced from an anthropogenic mixed source, which contributes 83.3% of Cd. The mixed source predominantly consists of industrial and mining activities, agricultural production, and traffic emissions. Elements Cu and Pb showed similar contribution rates of natural and mixed sources, both about 50%. Element Hg in soils primarily stems from dry and wet atmospheric deposition, which yields a contribution rate of 72.4%.

This study investigated the contents of eight heavy metals and related oxides in rocks with different lithologies and the soils formed in the Puhe river basin of Pingquan City. Based on the above investigation, this study analyzed the influencing factors and sources of soil heavy metals in the typical small watershed of the shallow mountainous area, aiming to provide theoretical support for water conservation and ecological restoration in the Beijing-Tianjin-Hebei region. Based on the contents and spatial distributions of soil heavy metals and combined with regional geological setting, this study delved into the influencing factors and sources of heavy metal elements in topsoil, deep soil, and soil parent materials using multiple statistical methods. The results show that heavy metals in topsoil and deep soil exhibited relatively similar contents and coupled spatial distributions. In terms of vertical distributions, the correlation coefficients of heavy metals were negative between topsoil and soil parent materials but positive between deep soil and soil parent materials. As indicated by the results, in the topsoil, elements Cr, Ni, Cu, Zn, and Pb are primarily derived from soil parent materials, while elements Cd, Hg, and As are subjected to the influence of mining. In contrast, the eight heavy metals in the deep soil predominantly stem from soil parent materials, with anthropogenic factors contributing to Cd and As.

This study aims to systematically assess the pollution risk of heavy metals in the soil-crop-human body system along the periphery of mining areas, thus providing a scientific basis for the classified management of ecological risks and safe crop production in mining areas. Hence, this study examined the soil and crops (rice, corn, and sweet potato) in arable land along the periphery of a typical mercury mining area in Chongqing City. The single-factor pollution index (P_i), Nemero composite index (P_综), and positive matrix factorization (PMF) model were employed to assess the pollution degree and ecological risk of soil heavy metals for source analysis. Moreover, the human health risk assessment model recommended by the United States Environmental Protection Agency (USEPA) was applied to assess the health risks of local staple crops for residents. The results are as follows: (1) The average contents of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the soil of the study area were all higher than the topsoil background values of Chongqing and China, suggesting that heavy metals are relatively enriched in topsoil; (2) The single-factor pollution index indicates that the over-limit ratios of Hg and Cd in the soil reached 96.29% and 92.59%, respectively, whereas rice, corn, and sweet potato samples with Cd content exceeding the value specified in the national food safety standard (GB 2762—2022) accounted for 16.67%, 18.75%, and 14.28%, respectively; (3) The Nemero composite index (P_综) was between 1.17 and 46.05, suggesting mild to heavy pollution in the study area, with heavy pollution primarily located around the mercury mining area and artisanal mercury smelters, as well as the lower reaches of the Rongxi River; (4) The PMF model analysis demonstrates that the heavy metals in the soil of the study area originate from three sources: natural source (47.21%), mining activities (16.00%), and a mixed source of mining and agricultural activities (36.79%). Specifically, Cd, Cr, and Ni are principally affected by the natural source, Hg by mining activities, As and Pb by the mixed source of mining and agricultural activities, and Cu and Zn are associated with the natural source and the mixed source of mining and agricultural activities; (5) The human health risk model reveals that the consumption of rice, corn, and sweet potato poses composite health risks for both adults and children. Rice consumption exhibits the highest risk index, especially in children, with the main risk factors being As and Cd.

In order to understand the content and distribution characteristics of heavy metals in soil and crops in Lipu,soil and crops (rice, Lipu taro, citrus, water chestnut) were collected. Todetermine the pH value of soil samples and the total amount of As, Cd, Cr, Hg, Ni, Pb, Cu, Zn and the form content of As, Cd, Cr, Hg, and Pb.The content of As, Cd, Cr, Hg, Pb in crop samples was measured.The bioconcentration factor (BCF) of heavy metal elements was calculated. The migration and transformation and ecological effects of heavy metal in the soil-crop system are analyzed. The results showed that:① The topsoil in the study area is predominantly acidic in the study area. The average contents of As, Cd, Cr, Hg, Ni, Pb, Cu, and Zn in the surface soil in the area were 13.57×10^-6, 0.33×10^-6, 87.06×10^-6, 0.153×10^-6, 27.49×10^-6, 30.46×10^-6, 27.94×10^-6, 82.53×10^-6.Respectively, all of which were higher than the national soil background values.②The heavy metal content in rice crops is higher than that in Lipu taro, citrus, and horseshoe.The heavy metal content is also different in rice roots, stems, and seeds.③ The bioaccumulation coefficient of heavy metal was generally high in rice. When comparing different parts of rice, the bioconcentration coefficients of heavy metals were greatest in the roots and least in the seeds. And when comparing different crops, the migration capacity of heavy metals in the soil-rice system was significantly higher than that of Lipu taro, citrus and water chestnut.④ The exchangeable state of Cd in the study area is significantly higher than As, Cr, Hg, and Pb. Cd is the most active soil heavy metal in the study area, it should be paid more attention to prevent excessive Cd in crops from causing harm to people.

China has accumulated massive data on total gamma radiation (γ) from the prolonged extensive surveys of uranium deposits. However, there is a marked lack of studies on radioactive environment assessment using these data. Based on the measurement principles of total gamma radiation and the absorbed dose rate in air, this study ascertained the relationships of the absorbed dose rate in air with the total natural gamma radiation and nuclide content and, accordingly, established the relationship between total gamma radiation and the absorbed dose rate in air. Furthermore, it analyzed the effects of instrument parameters on the measurement error, concluding that there existed a strictly linear relationship between the measured total gamma radiation and the absorbed dose rate in the air when b_K/b_U = 2.287 and b_Th/b_U = 0.430. Therefore, the b_K/b_U and b_Th/b_U ratios closer to both values correspond to more accurate absorbed dose rates in air converted from the measured total gamma radiation. Using the model of the Hunan Ionizing Radiation Measuring Station, this study calculated the coefficient for converting total gamma radiation into the absorbed dose rate in air, analyzed the error, and deduced the approximate uranium equivalent ranges of potassium and thorium in the instrument parameters. Furthermore, for the rock mass in Panjia Village, Guiyang County, Chenzhou City and the limestone area of Tuqiao Village in Yongxing County of the city, this study measured the total gamma radiation, gamma spectra, and absorbed dose rates in the air at the same stations. The results show that when the average nuclide content ratio C_K/C_U was less than 1 and C_Th/C_U ratio was less than 3, the absorbed dose rates in air estimated based on the total gamma radiation (measured using the FD3013 instrument) shared roughly the same error levels with those estimated based on energy spectra using the Beck formula, both yielding root mean square errors below 15%. As inferred from the average C_K/C_U and C_Th/C_U ratios of nuclides in China, the absorbed dose rate in air in most areas of China can be estimated using the total gamma radiation measured using an FD3013 instrument (or an instrument with similar performance). Overall, converting the total gamma radiation data from available extensive surveys of uranium deposits into effective absorbed dose rates in the air provides a methodological reference for rapid, large-area assessment of the external exposure level of natural radioactivity in the environment.

Underground cavities with shallow burial and small scale are difficult to detect. With the development of gravity sensing technology, the accurate and rapid acquisition of micro-gravity variations brings new opportunities for detecting underground cavities, and it has wide research and practical value for the detection of small-scale underground cavities. This paper systematically analyzes and studies underground cavities from three aspects: gravity basic theory, gravity detection technology, and gravity data processing and inversion. Under given body size and gravity data accuracy, the maximum burial depth of gravity detection is calculated using the bisection method. High-density acquisition and high-precision gravity detection methods are applied to the actual detection of an underground pedestrian tunnel in a certain area of a passenger station. A set of high-precision gravity grid data is obtained. The theoretical research and measurement results indicate that existing gravity instruments have the ability to detect underground cavities. By using the minimum curvature potential field separation method, 2.5D interactive inversion and the target area recognition three-dimensional physical property fast inversion method, the approximate SN distribution and burial depth of the underground pedestrian tunnel are obtained, which is approximately 2.5~5 m, consistent with the actual situation. This study has developed a complete gravity exploration process for detecting underground cavities, and it has certain reference value.

Urban main water supply pipelines are mostly buried along roads. Large pipe diameters and deep burial depths make it hard to detect their leakage in the early stage. Their leakage will severely influence urban traffic and residents' daily life. Hence, the leakage monitoring of water supply pipelines is particularly important. However, factors such as dense traffic lines, hardened road surfaces, and electromagnetic interference limit the application of the ground resistivity method and geological radars in pipeline monitoring. To make up for the shortcomings of existing monitoring methods, this study explored the cross-hole resistivity method for pipeline leakage monitoring. First of all, pipelines with and without leakage were simulated using forward modeling and inversion methods, analyzing the detection characteristics of the cross-borehole resistivity method. Then, electrode materials and burial methods were examined through experiments, solving the problems of electrode corrosion and weak electric field signals. Finally, an experimental site was set up near a water supply pipeline in Beijing, obtaining multi-phase monitoring data using the cross-borehole resistivity method. Through comparative analysis of multi-phase resistivity sections, this study analyzed the changes in pipeline leakage, delineating the leakage influence scope, which was verified by the leakage data from the waterworks. The satisfactory monitoring results suggest that the method proposed in this study can be referenced for similar pipeline leakage monitoring in cities.