Airborne geophysical surveys, characteristic of being green, economical, efficient, and subjected to less influence by surface factors, serve as the one of most effective means of basic surveys and scientific research on the Qinghai-Tibet Plateau. This study reviewed the progress in the airborne geophysical surveys in the Qiangtang Basin of the Qinghai-Tibet Plateau in the past thirty years, systematically summarizing the progress and geological interpretation results of comprehensive airborne geophysical surveys in the basin. Furthermore, this study presented research progress and understanding of major basic geological issues of the basin, such as the basin's boundaries, central uplift zone, basement properties, deep structures, and cover characteristics, as well as the identification of favorable structural areas for oil and gas exploration. Finally, based on an analysis of the developmental trends of airborne geophysical surveys in the Qiangtang Basin, this study proposed opinions and suggestions for key research directions in the future.

In the Prospecting Breakthrough Strategy (2011~2020), China has made significant progress in the exploration of gold deposits, demonstrating considerable prospecting potential. Element sulfur, a mineralizer, is closely associated with the formation of gold deposits, proved to be the most significant element in gold deposit formation by scholars at home and abroad. Sulfur isotopes have been extensively used to trace the sources of minerals in gold deposits. Different gold deposits reside in distinct geological settings. Since sulfur isotopic compositions are governed by various sulfur sources, sulfur isotopes in gold deposits can reflect the geological settings of mineralization. The ore-district-scale spatio-temporal distribution of sulfur isotopes has theoretical implications, playing a significant role in guiding ore prospecting. The gold resources in China are distributed in 42 gold ore districts, typified by Jiaodong, Xiaoqinling, and Yunnan-Guizhou-Guangxi. This study comparatively analyzed and summarized the characteristics of sulfur isotopes in the three typical gold ore districts, providing theoretical and methodological support for future gold prospecting.

Southern China boasts great potential for normal-pressure shale gas resources,with distribution areas primarily including the peripheral complex structural areas and the extrabasinal fold belts of the Sichuan Basin.These areas exhibit intricate surface and subsurface geological conditions,leading to poor seismic acquisition quality,low imaging accuracy,and unclear varying patterns of sweet spot parameters.This study systematically summarized the research achievements and technical advances in the seismic acquisition,image processing,and reservoir prediction for normal-pressure shale gas in southeastern Chongqing,including:①The development of variable-density 3D observation system design technique and the seismic excitation and reception technique for complex mountains with limestone surfaces,ensuring sufficient sampling of the reflected wave field in complex subsurface structures and improving data quality and construction efficiency;②The optimization of prestack seismic preprocessing technique for complex mountains,imaging techniques for complex structures in basin-margin transition zones, and imaging techniques for synclinal structures in extrabasinal fold belts,achieving resulting profiles with high signal-to-noise ratios,wide effective frequency bands,and high structural imaging accuracy;③The quantitative prediction of the thickness,formation pressure coefficient,and brittleness of high-quality shales based on research on petrophysical characteristics;the quantitative prediction of the organic carbon content,gas content,and porosity of shales based on statistical petrophysics;the quantitative prediction of fractures formed due to the superimposed effect of multi-stage structural modifications based on the paleo-stress field evolution revealed using the finite element simulation technique;and the ascertainment of the distribution patterns of the current in-situ stress field using the current stress field prediction technique developed using the combined spring model.The above breakthroughs have effectively guided the sweet spot prediction,exploration,and production of normal-pressure shale gas,providing a basis for the discovery of the Nanchuan normal-pressure shale gas field.Subsequent research should focus on more scientific and reasonable seismic acquisition techniques based on seismic reception using 5G wireless nodes,high-precision automatic image processing technologies for high-steep structures in complex mountains,and integrated geology-engineering-economy seismic evaluation methods for sweet spots.

Significant aeromagnetic and gravity anomalies were found in the ultra-deep coverage zone of the Pandian area in the northwestern Shandong Province. Through systematic verification of gravity and magnetic anomalies, a breakthrough in prospecting for deep skarn iron deposits has been achieved through several boreholes around the Pandian gravity-magnetic anomaly zone. However, the gravity-magnetic anomaly zone spreads extensively and its characteristics cannot directly indicate the prospecting target, thus some boreholes failed to find ores or revealed poor ore-finding conditions. Hence, to accurately delineate the ore-forming location in the gravity-magnetic anomaly zone and achieve a further breakthrough in ore prospecting, this study conducted the wide-field electromagnetic (WFEM) sounding in the verified Pandian gravity-magnetic anomaly zone. Combining the drilling verification, this study delineated the deep ore-forming interval of skarn iron deposits in the deep coverage zone and the favorable structural plane for ore-forming, suggesting the deep fine-scale prospecting targets.

Industrial oil flows have been successively obtained from the basal conglomerates of the Cretaceous Qingshuihe Formation in the Shinan area, Junggar Basin. However, this set of reservoirs exhibits multi-layer three-dimensional oil-bearing properties and significant vertical and horizontal variations. Therefore, there is an urgent need to overcome the challenge of the identification and fine-scale characterization of reservoirs. Based on the accurate calibration of seismic and geological horizons, this study reconstructed the paleogeomorphology of the first member of the Cretaceous Qingshuihe Formation using based on the seismic flattening and residual thickness methods in three steps. By combining the reservoir prediction through natural gamma-ray pseudo-acoustic wave inversion, this study roughly identified the predominant factors controlling sedimentation and the spatial distributions of sand bodies. The results of this study provide an effective method combination for predicting Cretaceous reservoirs in the Shinan area. Furthermore, these results offer a sufficient scientific basis for oil and gas exploration in the glutenite reservoirs of the Cretaceous Qingshuihe Formation, thus effectively reducing the exploration risk.

Investigating the spatial distribution of permafrost is critical for cryosphere research. At present, China's investigation concerning the spatial distribution of permafrost generally employs the detection method of ground geophysical exploration combined with logs to obtain local point or line data. Alternatively, different remote sensing models can be used to simulate and estimate the thickness of regional permafrost. This study inferred the spatial distribution of permafrost based on airborne time-domain electromagnetic (TDAEM) data and resistivity calculation results. The comparative analysis of the inference results and the known drilling data reveals an average error of 18.5% between the permafrost thickness inferred from the inversion results of TDAEM data and the result determined by borehole temperature measurements. This suggests that the TDAEM method exhibits high effectiveness and accuracy in permafrost thickness investigation. With technical advantages like high efficiency and minor topographic influence, the TDAEM method can be applied to the large-scale, rapid, and quantitative permafrost investigation in the Qinghai-Tibet Plateau and the Greater Khingan Range in northeast China. Therefore, this study provides a new and effective technical solution for a comprehensive investigation of the spatial distribution of permafrost and its influence on ecological environment changes.

This study aims to ascertain the accumulation characteristics of natural gas in the deep-water oil and gas fields in the Qiongdongnan Basin. To this end, it performed continuous multi-component carbon isotope measurements for natural gas wells in the basin. Based on the comparative analysis of a continuous carbon isotope profile from a key well in the basin and the carbon isotope values from key intervals in surrounding wells, this study delved into the genetic types and sources of natural gas in the key well. The results show that dry gas occurs above the first member of the Sanya Formation, dominated by biogenic and secondary biogenic gases. In contrast, wet thermogenic gas exists below the second member of the formation, primarily including associated gas. Besides, natural gas in the BD21-1 block originates from two sources: Eocene high-maturity oil-formed gas and low-maturity gas with a special genesis from the Yacheng Formation. Overall, multi-component carbon isotope logging is effective in investigating the genetic types, sources, and maturity of natural gas.

For deep coalbed methane (CBM) exploration and production, accurate in situ stress prediction holds critical significance for safe and efficient drilling and completion of wells. Deep CBM reservoirs, once considered restricted areas for exploration and exploitation, have been highly anticipated owing to their high yields in recent years. However, their in situ stress prediction model has not been investigated effectively. Hence, this study systematically analyzed six in situ stress prediction models commonly used for conventional oil and gas reservoirs and unconventional gas (like CBM) reservoirs. Based on these prediction models, this study calculated the in situ stress, and found that the combined spring model and the Newberry model yielded relatively high accuracy through comparative analysis of closure pressures. To improve the accuracy of in-situ stress prediction models, the effective stress coefficient of coal rocks was employed to optimize the two models. The optimized in-situ stress models yielded prediction accuracy errors reduced by 4%, roughly meeting the requirements of in-situ stress prediction accuracy for deep CBM exploration and production in the Daji block.

This study aims to explore the distribution characteristics and occurrence patterns of lithium in medium-fine-grained rocks and its paragenetic or associated relationship with minerals such as tungsten, tin, niobium, tantalum, beryllium, and rubidium. Hence, it analyzed the distribution characteristics and diagenetic and metallogenic processes of nonferrous-rare metals in the Xianghualing orefield. With the exposed granitic rock masses as the center, this study divided three ore-forming sections of rare metal lithium, i.e., the Laiziling-Nanjichong, Jianfengling-Xianghuapu, and Tongtianmiao-Yaoshanli ore-forming sections. Moreover, lithium-rich mineralized bodies were discovered in the medium-fine-grained rocks of the former two ore-forming sections. Lithium converges and accumulates in the interior and top of medium-fine-grained granitic rock masses, at the automorphism and alteration positions of high-emplacement apophyses and vein fronts and edges, or in the areas enclosed by silicon-rich quartz veins at the contact zone with silicon-rich surrounding rocks. Dividing these mineralization and alteration sections serves as a crucial approach for exploring medium-fine-grained rock type lithium ore bodies in the Xianghualing orefield.

Since individual geophysical exploration methods suffer the multiplicity of solutions, comprehensive geophysical prospecting has been extensively applied in deep ore prospecting presently. This study conducted the geological exploration of the Duhu porphyry copper deposit in Xinxing County using multiple geophysical methods such as high-precision magnetic survey and controlled source audio-frequency magnetotellurics (CSAMT). It was inferred that the CSAMT-derived medium-low resistivity anomalies and the low-gentle anomalies derived from the high-precision magnetic survey serve as significant prospecting indicators. Satisfactory results were achieved in follow-up verification of the anomalies. Specifically, copper, molybdenum, silver, and gold mineralized bodies with a cumulative thickness of 178.2 m were identified in a 1 000 m deep borehole, with the highest copper grade of 1.45%. The application of comprehensive geophysical prospecting holds great significance in guiding the exploration of porphyry copper deposits in western Guangdong.

Birimian rocks, the most significant Au ore-forming rocks in western Africa, are widespread in Harper, southeastern Liberia. As indicated by the geochemical parameters from the 1∶250 000 stream sediment survey of this region, elements Au and Hg exhibit high enrichment and high differentiation while element As manifests enrichment and high differentiation. These findings suggest considerable potential for Au prospecting. Based on the correlation analysis of elements, this study selected factors F1 (for the Au-Hg-Pb-Sn association) and F2 (for the As-Sb-W association) to effectively guide the exploration of gold deposits. Thirteen composite anomalies were delineated by extracting the anomaly information of Au, Hg, As, and Sb from the two principal factors, effectively reflecting the anomaly distributions of different gold deposits or ore occurrences. The geological and mineral surveys in anomaly areas reveal that areas HS1-HS3 and HS12-HS13 with composite anomalies characterized by directional distribution and high intensities show distinct Au mineralization information. Based on this, two major Au prospects, i.e., Seethum New and Behwan, have been identified for further detailed exploration.

As mature oilfields are in their middle to late exploitation stage, the Gaotaizi oil layer exhibits significantly increased water saturation, elusive longitudinal stratification, and unknown distribution patterns of regional residual oil. These complicate the potential exploitation, energy conservation, and emission reduction. To ascertain the distribution of residual oil in the Gaotaizi oil layer in order to guide production operations and clarify potential targets, this study identified the longitudinal distribution of residual oil in the study area using the pulsed neutron-neutron (PNN) logging technique. The comparison between the monitoring results and production data of 10 wells revealed a coincidence rate of measures of 80%. The results of this study show that the PNN logging technique can be used to effectively identify the longitudinal distribution of residual oil in reservoirs and yields encouraging application performance in guiding the hole filling and water plugging for single wells in high-water-cut layers, thus increasing oil production. This technique has increased the evaluation accuracy of residual oil saturation in the Gaotaizi oil layer in the mature oilfield. It can provide technical support for formulating and adjusting subsequent oilfield exploitation schemes and offer a scientific basis for further guiding efficient reservoir exploitation, energy conservation, and emission reduction.

Except for the Sichuan Basin, the marine shales in the Longmaxi Formation in Hubei show great potential for shale gas exploration. Logging technology is highly mature in the exploration and development of hydrocarbons. This study systematically analyzed the log response characteristics of gas-bearing shales in the Longmaxi Formation based on logs obtained from well WY1 in the Laifeng area. As indicated by the analysis results, the gas-bearing shales of the Longmaxi Formation in well WY1 are characterized by high natural-gamma-ray values, high contents of uranium, thorium, and compensated neutrons, high interval transit time, and low density. Their deep and shallow lateral resistivity is lower than that of the underlying Baota Formation carbonate rocks but is higher than that of the sandy shales. Moreover, the positive differences indicate that high-angle fractures occur in the shales. The superimposition of log curves and the analysis of cross plots for gas-bearing shales reveal that ① the superimposed log curves of both natural gamma ray-lithologic density and interval transit time-lithologic density show significant positive differences, while those of both natural gamma ray-compensated neutrons and interval transit time-compensated neutrons show significant negative differences; ② the superimposed log curves of interval transit time-lithologic density indicate the gas-bearing intervals the most accurately; ③ the organic-rich gas-bearing shales can be identified the most effectively using the log cross plots of interval transit time-compensated neutrons, compensated neutrons-natural gamma ray, and deep lateral resistivity-compensated neutrons.

Distributed acoustic sensing (DAS) technology, one of the most advanced sound field detection technologies, can achieve distributed, long-distance, and high-precision real-time detection of the ambient vibration and sound field information interacting with optical fiber. The optical fiber exploration system of the DAS technology solves the problems of high cost and deployment difficulty of conventional geophones in complex geological environments. In recent years, the DAS technology has experienced rapid development, especially in monitoring application scenarios that require long-term and large-scale deployment. However, its systematic understanding is insufficient due to divergent research results. To further understand the research advances of the DAS technology in geophysical exploration for more effective subsequent research, this study systematically classified and summarized the development history of the DAS technology and its recent research results in geophysical exploration based on the oil and gas, marine, and environmental engineering application scenarios through literature research. This study focused on the development process of the DAS technology in different directions, the research advances in data processing, and relevant literature with specific results. Finally, this study generalized the development trend and urgent problems of the DAS acquisition system, analyzing the DAS development prospect.

Lithology identification, as a major geological task, strongly underpins the exploration of solid minerals, oil, and gas. Since the physical properties of rocks bridge lithologies and geophysical fields, their differences can be used for lithology identification. However, the physical property data of different rocks frequently overlap to some extent, posing challenges to accurate lithology identification using cross plots alone. The K-nearest neighbor (KNN) model is suitable for multi-class classification since it is a simple and direct machine learning method with high accuracy and sensitivity. This study introduced a feature-weighted KNN model for lithology identification. In this model, different weights were assigned to different features by combining the conventional KNN model with the information gain of attribute features. This allowed for intuitive reflection of the importance of attribute features to classification. Experiments show that compared to the conventional KNN model, the feature-weighted KNN model can more significantly identify lithologic boundaries, thus improving the overall accuracy and stability of lithology identification.

Acquiring empirical Green's functions with a real and high signal-to-noise ratio serves as a prerequisite for deriving surface wave dispersion and inverting underground structures.However,the distribution of actual noise sources differs from the theory,and the energy and quantity of noise sources are limited in the high-altitude areas.Acquiring empirical Green’s functions with a high signal-to-noise ratio is challenging,apart from a prolonged data acquisition period required.Given these,this study presented a method for screening ambient noise data based on power spectral density.Using this method,this study screened 92-hour ambient noise data from a high-altitude area.Consequently,this method significantly reduced the calculation time of cross-correlation,effectively extracted surface waves with a high signal-to-noise ratio,reduced the interference waves with high apparent velocities,and obtained a high-resolution shallow shear wave velocity structure of shallow parts with burial depths ranging from 0~140 m.This study provides a novel method for challenging,short-term exploration of water conservancy and hydropower generation in high-altitude areas.

The progress in seismic acquisition techniques characterized by wide azimuths,wide frequency bands,and high densities has greatly promoted the application of the prestack P-wave fracture inversion technique based on the azimuthal anisotropy theory.Azimuthal anisotropy-based inversion can yield the azimuths and intensities of fractures.However,different inversion techniques yield different parameters for fracture intensity characterization,resulting in inconsistent inversion results.Consequently,the azimuthal anisotropy-based inversion results of fractures are non-unique,leading to confusion about accurate results.Based on the Thomsen anisotropy theory,as well as the interrelationships between fracture models(the Hudson coin model and the Schoenberg linear sliding model),this study established the connections of anisotropic parameters between different fracture inversion techniques(VVAZ,Ruger's approximation,and Fourier series),presenting the real meanings and mathematical expressions of results from different azimuthal anisotropy-based fracture inversion techniques.Additionally,this study summarized the relationships of parameters between different inversion techniques and fracture models,further deepening the research on azimuthal anisotropy-based fracture inversion.This study lays solid theoretical and technical foundations for large-scale fracture detection based on the seismic data obtained using the seismic acquisition techniques featuring wide azimuths,wide frequency bands, and high densities.

In recent years, the self-potential method has played a significant role in the exploration and evaluation of seafloor massive sulfide resources. This study explored the 3D forward and inverse modeling algorithms for self-potential based on the PARDISO direct solver. First, the finite volume method was employed to discretize the self-potential control equation, and the PARDISO direct solver was utilized to improve the forward modeling efficiency. The reliability of the forward modeling algorithm was verified by comparing the numerical solution with the analytical solution. The 3D inverse modeling algorithm considered the topographic factor and incorporated the minimum support constraint and depth weighting into the objective function. The inversion results of theoretical model data effectively reconstructed the ore body structure. Finally, the self-potential data obtained from indoor sandbox experiments were inverted using the inverse modeling algorithm, obtaining that the current density anomaly was roughly consistent with the position of the metal bar. Therefore, the inverse modeling algorithm proposed in this study holds critical significance for subsequent inversion of large-scale spontaneous potential data.

Deep-water areas have gradually become the exploration targets of offshore oil and gas resources.Due to the intricate geological conditions of these areas,seismic imaging of moderately deep reservoirs suffers low signal-to-noise ratios and resolution,inevitably affecting the exploration and exploitation of oil and gas resources.To improve the quality of seismic data of moderately deep reservoirs in deep-water areas,this study first acquired seismic data at the same location in a slope break using stereo and planar sources under the same acquisition parameters.Then,after being processed using the same workflow,the seismic data were subjected to comparative analysis from the perspective of wavelets,shot gather spectra,near-trace spectra,superimposed profile spectra,and final imaging.The results indicate that the wavelets of a stereo source outperformed those of a planar source in terms of energy intensity and ghost reflection interference.Moreover,for moderately deep reservoirs of the deep-water area,a stereo source exhibited broader frequency bands and especially rich frequencies within 30~80 Hz.These features enhanced the resolution of seismic profiles and the imaging quality of seismic data.Thus,compared to planar sources,stereo sources enjoy more advantages in improving seismic imaging of moderately deep reservoirs in deep-water areas.Therefore,stereo sources can be employed to acquire seismic data of moderately deep reservoirs with complex geological conditions in deep-water areas,and the purpose is to improve the imaging quality of seismic data.

Since non-zero-offset time-lapse vertical seismic profiling (VSP) data contain abundant near-well wave field information,the VSP reflection information and seismic attributes can be applied to effectively monitor the migration of injected fluids near wells,boasting a broad application prospect.Due to the limitation of observation methods,non-zero-offset time-lapse VSP data exhibit limited superposition times,thus demanding more stringent processing for two-phase VSP data.By introducing the repeatability analysis and consistency processing method of two-phase data into the conventional processing technology for non-zero-offset VSP data,this study developed a processing technology flow for non-zero offset time-lapse VSP data.Moreover,this study conducted analysis and tests of the methods for processing the intra-shot consistency of time-lapse data and the consistency of two-phase data.As verified by the application in well A,the processing flow and key technology for non-zero-offset time-lapse VSP data proposed in this study enjoy high operability and practicability and,thus,have the potential for wide applications.

Field seismic data contain various random noise and irregular channel missing. Their simultaneous reconstruction and denoising is necessary for subsequent data processing. Currently, most simultaneous reconstruction and denoising methods only use a single sparsity or rank reduction constraint. The sparsity constraint exhibits high efficiency but lacks adaptability to various data. In contrast, the rank reduction constraint can adapt to various data but shows a high computational cost. To take a full advantage of different constraints, this study proposed a method for simultaneous reconstruction and denoising of seismic data based on combined constraints. This method regards projection onto convex sets (POCS) based on Fourier transform as the sparsity constraint, and damped multichannel singular spectrum analysis (DMSSA) as the rank reduction constraint. It employs the truncated singular value decomposition (TSVD) algorithm and the exponential threshold equation, fully utilizing the high computational efficiency of the sparsity constraint and the strong adaptability of the rank reduction constraint. As indicated by the processing results of theoretical and field data, this method based on combined constraints can consider and utilize the spatio-temporal correlations of seismic data, achieving higher signal-to-noise ratios via fewer iterations compared to methods based on a single constraint.

Specific computational tools assist geologists in identifying and classifying the lithology of rocks in oil well exploration,reducing costs,and enhancing operational efficiency. Machine learning methods integrate a vast amount of information,enabling efficient pattern recognition and accurate decision-making. This article categorizes the lithology of five oil wells in the Norwegian Sea,randomly dividing the data into a training set (70%) and a test set (30%). Using multivariate well log parameter data for training and validation,the application effectiveness of models such as Multilayer Perceptron (MLP),Decision Tree,Random Forest,and XGBoost is compared. The research results indicate that the XGBoost model outperforms others in terms of data generalization,achieving an accuracy of 95%. The Random Forest model follows with an accuracy of 94%. Meanwhile,Multilayer Perceptron (MLP) and Decision Tree models exhibit good robustness,with accuracies of 92% and 90%,respectively.

With the development of society,high-quality magnetotelluric signal acquisition is becoming more and more difficult because of various types of human interference are increasingly intensified. Scholars have proposed many corresponding denoising methods for different types of noise to improve data quality. It is impossible to manually interpret each data before denoising due to the huge amount of data. So an efficient noise recognition and classification method is urgently needed. Based on this, artificial neural network is applied in the classification of magnetotelluric time series in this paper. Four types of time series,namely,simulated square wave, power frequency, impulse noise, and measured noiseless data, were used to conduct noise classification training and measured data classification on LSTM、FCN、ResNet、LSTM-FCN and LSTM-ResNet models. The results show that FCN and LSTM-FCN has a relatively good effect on the classification of magnetotelluric time series. Among them, the highest classification accuracy of FCN measured data can reach 99.84%, and the average time for each epoch is 9.6 s. LSTM-FCN has higher classification accuracy than FCN,the highest classification accuracy of measured data sets is nearly 100%, but the average time for each epoch is 24.6 s, and it is easier to overfit than FCN. Overall, LSTM-FCN can achieve higher classification accuracy when the amount of data is relatively small, if the amount of data is large, it is necessary to consider the time cost,using FCN is more appropriate. Finally,the magnetotelluric data containing different types of noise was successfully processed using the magnetotelluric noise processing system which constructed by the LSTM-FCN classification model and the LSTM denoising model.

Due to factors such as environment,the signals received by ground-penetrating radar (GPR) contain various clutter interference,posing high challenges in subsurface anomaly interpretation and late-stage imaging.Clutter,primarily including noise,antenna-coupled waves,and surface direct waves,cannot be eliminated effectively using single data processing methods.Hence,this study proposed a spatiotemporal combined clutter suppression method. In the temporal dimension,threshold processing based on empirical mode decomposition(EMD) was applied to the data of all survey points in the echo profile,achieving effective noise removal.In the spatial dimension,the Karhunen-Loeve(KL) transform was employed to remove residual interference in the entire radar echo profile by utilizing the correlation of target echoes and the randomness of clutter at all survey points.Both theoretical simulation and measured data processing verify that the method proposed in this study is effective in eliminating clutter and highlighting weak signals.

The buried-hill reservoirs in the Qiongdongnan Basin of the South China Sea exhibit intricate reservoir spaces and numerous fractures, leading to their pronounced heterogeneity. Since granite sediments spread across the study area, it is critical to effectively evaluate the development of fractures in granite reservoirs. Based on the COMSOL Multiphysics software and the finite element method, this study simulated the use of array acoustic logging to detect granite reservoirs with different widths, dip angles, and lengths, summarizing the response characteristics of fractures in different development states. The results are as follows: (1) Shear waves in fractured formations are subjected to non-significant influence of fracture widths, and their attenuation is inversely proportional to fracture dip angles and directly proportional to fracture lengths; (2) Stoneley waves manifest significant response to the changes in fracture widths, dip angles, and lengths, and their attenuation is proportional to both fracture widths and dip angles; (3) The attenuation of Stoneley waves is directly proportional to fracture lengths below 0.1 m but shows subtle response to fracture lengths above 0.1 m. The results of this study provide a basis for determining the development state of fractures in granite reservoirs using the array acoustic log method.

To ascertain the nutritional quality, oil content characteristics, and growing environment of camellia oleifera in Youyang, Chongqing, China, this study analyzed the fatty acid composition of camellia oil and the oil content of camellia oleifera fruits produced in different strata. Furthermore, this study evaluated the soil nutrients and environmental quality of the site. The results indicate that the camellia oil from Youyang exhibited a similar fatty acid composition to olive oil, suggesting that camellia oleifera seeds are valuable high-grade oilseeds. The oil content of camellia oleifera fruits is significantly associated with strata. Camellia oleifera fruits produced in the Permian strata exhibit the highest oil content, followed by those in the Silurian and Ordovician strata sequentially. The cause of the differences lies in the varying geochemical composition of soils in different strata. The camellia oleifera site in Youyang manifests average soil nutrients but relatively high soil environmental quality, with only slightly over-limit Cd content. Therefore, camellia oleifera should be cultivated by applying various fertilizers in a scientific manner to ensure its healthy growth.

n-alkanes, exhibiting stable chemical properties, are ubiquitous in nature. They are favorable indicators of the source of organic matter. Using the gas chromatography-mass spectrometry (GC/MS), this study detected n-alkanes in the surface sediments sampled from the Fangchenggang sea area in September 2021. It analyzed their content and distribution, as well as their source based on characteristic parameters. The results are as follows: ① The n-alkanes of the Fangchenggang sea area manifested a content range of (67.51~850.08)×10^-9 (dw), averaging 476.69×10^-9 (dw), with high values primarily distributed in the southern sea area of Qisha Peninsula; ② They were principally composed of extensive n-C₁₄~n-C₃₅ n-alkane homologues in a bimodal distribution. The former peak group displayed an even-carbon number advantage, while the latter showed an odd-carbon number advantage; ③ The terrestrial-marine alkane ratio (ΣT/ΣM), carbon predominance index (CPI), and terrestrial-marine alkane predominance ratio (TAR) all indicate a significant terrestrial influence on n-alkanes in the Fangchenggang sea area; ④ The average chain length (ACL), alkane index (AI), and Pmar-aq further suggest that n-alkanes were mainly from terrestrial herbs; ⑤ The T-ALK/C₁₆ ratio implies that the Fangchenggang sea area experienced oil pollution; ⑥ The pristane/phytane ratio (Pr/Ph) reveals that n-alkanes in the sediments of the Fangchenggang sea area formed in an oxidizing environment.

Determining the content and absorption by crops of germanium (Ge) in soils of cultivated land holds great significance for the development and utilization of Ge in the land, as well as the scientific seed selection for the land. However, few studies on the Ge element in soils of cultivated land in Qixingguan District have been reported. Based on the data from a project of the geochemical investigation and evaluation of the land quality in the district, this study made statistics of geochemical parameters such as the Ge content and analyzed the geochemical characteristics of Ge in soils and the absorption of Ge by crops. The results show that the soils of cultivated land in Qixingguan District exhibit a Ge content ranging from (0.86~2.48)×10^-6 (average: 1.74×10^-6), which is equivalent to the background value of Ge in China. Based on the geostatistical analysis, this study determined that Ge-rich cultivated land covers an area of 65 853.54 hm², accounting for 47.41% of the total cultivated land in the district, and is primarily distributed in the northwestern and southwestern portions. The biological absorption coefficients (Ax) to Ge in soils by crops are all below 1%, suggesting an extremely low absorption level. This study explored the causes of Ge enrichment in the soils and the environmental factors affecting Ge absorption by crops using methods such as correlation analysis, drawing the following conclusions: ① The Ge content in soils is principally governed by soil parent materials, accompanied by the influence of pedogenetic weathering process for soil formation. These factors, coupled with high organic matter content and slightly acidic soil, contribute to the Ge enrichment in the cultivated land of Qixingguan District; ② The correlation between Ax and pH is slightly negative in acidic soils but positive in neutral to alkaline soils, implying that slightly acidic soil reduces the absorption of Ge by crops in the study area.

This study aims to investigate the characteristics and influencing factors of selenium (Se) content in the tea leaf-rhizosphere soil system of the Liubao tea in Wuzhou, Guangxi. With the main tea gardens in Liubao and Shizhai towns, the core production areas of the Liubao tea, as study areas, this study conducted statistical analysis of the Se content in the tea leaves, rhizosphere soils, and tea leachate samples of the Liubao tea. The results show that: ① The Se content in soils of the study areas ranged from (0.40~1.98)×10^-6, averaging 1.08×10^-6; ② The Se content in Liubao tea leaves was between (0.03~0.25)×10^-6, averaging 0.07×10^-6, with a Se enrichment rate of 68%; ③ The leaching rates of Se in tea leachate ranged from 0~23.95%; ④ The Se content in the rhizosphere soils of tea gardens principally depended on soil parent materials and silica-sesquioxide ratios; ⑤ The P and N elements in soils can facilitate the absorption of soil Se by tea leaves, while the iron and aluminum oxides in acidified soils hinder the full utilization of soil Se by the Liubao tea. Hence, appropriate biochemical and agronomic measures are recommended for acidified soil amelioration to enhance the Se enrichment ability of the Liubao tea.

To discern the community structure of phytoplankton in the water of Honghu Lake Basin, this study deployed 10 sampling sites in Honghu Lake in October 2021, and evaluated the phytoplankton community using the diversity indices. The results show that there were 66 species of phytoplankton belonging to 49 genera in six phyla, of which the cyanophyta was the most species, followed by bacillariophyta. The phytoplankton biomass of the Honghu Lake Basin in winter ranged from 7.85~42.45 mg/L, averaging 22.35 mg/L. A comprehensive evaluation of the nutrient status of the lake water was conducted based on Margalef's richness index (M), Shannon-Weiner's diversity index (H), Simpson's diversity index (D), Pielou's evenness index (J), and the species dominance index (Y), suggesting that the Honghu Lake Basin water was moderately to severely polluted. This study holds that the water quality of the Honghu Lake Basin can be improved from the following aspects: ① The water protection of the Honghu Lake Basin should be enhanced by strictly controlling the inflow of various water pollutants from downstream and surrounding areas, implementing timely and efficient prevention and control of rural water pollution in the lake area, and properly organizing the balanced harvesting of aquatic phytoplankton; ② The water environment treatment should be strengthened to gradually restore the self-purification capacity of the lake water; ③ The publicity efforts should be intensified by regularly conducting educational activities on water pollution prevention and control in rural areas, residential communities, and schools.

The stability assessment of strip mine slopes is a fundamental means to prevent slope accidents. To investigate the influence of step topographies on the exploration using the high-density resistivity method on strip mine steps, this study conducted flume experiments for simulation using similar materials to explore the current field distribution in the profile to be surveyed. The experimental results show that: (1) The shallow positions near the upper and lower slope lines and the breadth line of the cleaning berm exhibited high current densities and even current distributions; (2) The middle positions manifested sharply changed current densities, with their contours akin to the step topography; (3) The deep positions displayed low current densities and tardy current changes; (4) A significant current gathering effect was observed near the slope bottom line on the profile; (5) Compared to flat topographies, step topographies exhibited high current densities and uneven current distributions. This suggests that in the exploration using the high-density resistivity method, step topographies in strip mines can cause abnormal inversion results for the middle positions and positions near the slope bottom line.