The telecontrol electrode array is a new type of electrode array for power supply and observations that utilizes the carrier waves of the power-supply and measurement wires used in conventional electrical prospecting to transmit signals. By remotely controlling a series of coded electrode switches between various wires and their connections, this array allows for orderly power supply and measurements. This array enables flexible spacings between electrodes and the gradual expansion of the distances between power supply electrodes via remote control, thus achieving a gradient-based sounding array. The borrowing-line remote controller can be used combined with single-channel, multi-channel, and high-density resistivity instruments, and the combined arrays can perform 2D/3D electrical prospecting more effectively. Followed by the brief introduction of the principle of the borrowed-line telecontrol electrode array, this study discusses the applications and examples of this array and several combined arrays in the resistivity method and induced polarization (IP).

The Galinge iron deposit in Qinghai is overlain by deposits measuring greater than 150 m in thickness. The great burial depths of ore bodies lead to gentle magnetic anomaly morphology, making it difficult to characterize the spatial distribution of ore bodies. Therefore, this study employed three-dimensional magnetic anomaly inversion to determine the three-dimensional distribution characteristics of subsurface magnetic intensity in the study area. Given the prior information of non-magnetic surrounding rocks, the three-dimensional magnetic intensity model clearly presented the spatial distribution of the ore bodies and reflected the presence of intense magnetic bodies at depths of less than 500 m in existing boreholes. Accordingly, it can be inferred that there exist concealed ore bodies at depths exceeding 500 m in the study area. The results of this study suggest that three-dimensional magnetic anomaly inversion can effectively improve target identification, providing clear information on the horizontal positions, depths, and scales of magnetic ore bodies. The proposed inversion method can offer strong support for drilling design and reserve estimation, warranting promotion in detailed exploration of solid minerals.

Marine controlled-source electromagnetics (MCSEM) is used to explore resources such as oil and gas hydrates, as well as deep geological structures, by revealing resistivity differences below the seabed. Different excitation frequencies correspond to varying detection depths. To enhance the resistivity imaging of targets beneath the seabed, this study investigated the MCSEM-based technology for generating arbitrary-frequency waveforms to flexibly alter the excitation frequency and improve the exploration effectiveness and efficiency. Using the direct digital frequency synthesis (DDS) chip AD9833 and the joint control of a microcontroller and a complex programmable logic device (CPLD), this study achieved the generation of arbitrary-frequency waveforms with limited precision. The test results indicate that this technology can effectively enhance the spectral adaptability and flexibility of MCSEM.

The Mangling ore concentration area with intense magmatic activity has become a focal area for deep prospecting in the North Qinling tectonic belt in recent years. The formation of molybdenum deposits in this area is closely related to small Late Jurassic acidic intrusions. To achieve breakthroughs in deep ore prospection within this area, this study conducted the wide-field electromagnetic sounding over the concealed Yaozhuang intrusion delineated based on gravity anomalies. The results indicate the presence of pronounced high-resistivity anomalies at depth, and it is inferred that the protruding part of the anomalies corresponds to the concealed Yaozhuang intrusion. The resistivity inversion results roughly delineated the variations in the top surface of the intrusion, with the elevations and N-S width of the top surface estimated at -300~620 m and 1300~1600 m, respectively. Drilling in the most favorable deep mineralized part confirmed the presence of the concealed intrusion and concealed molybdenum ore bodies. The results of this study demonstrate that the wide-field electromagnetic sounding method exhibits great sounding depths and high resolutions, serving as an effective method for deep ore prospecting in the Mangling ore concentration area.

In shallow engineering investigations, the small-loop transient electromagnetic (TEM) system is challenged by limitations such as overweight equipment, significant transmitter-receiver mutual inductance, and high manpower requirements. Hence, this study introduced an improved system. Based on the opposing-coils transient electromagnetic (OCTEM) theory, this study calculated the magnetic field distribution of the generalized opposing-coils antenna device. Furthermore, it designed and developed efficient portable antennas and the supporting system (collectively referred to as the portable OCTEM system). Subsequent field experiments demonstrate that while ensuring exploration accuracy, the portable OCTEM system can enhance the investigation efficiency by effectively mitigating the transmitter-receiver mutual inductance and significantly reducing manpower requirements. This study preliminarily verifies the feasibility of the portable OCTEM system, providing a novel technology route for developing downsized shallow exploration equipment.

Non-destructive testing of the internal structural characteristics of ancient buildings is the key to preserving cultural relics.To determine the structures and internal defects of the ancient Great Wall in Linhai City,this study performed non-destructive testing of the wall structures in different orientations using a ground-penetrating radar (GPR) combining 100 MHz and 270 MHz antennas.The testing results show significant structural stratification in the ancient Great Wall.The GPR signal-reflected images reveal clear internal wall defects like pores,cracks,voids,and other hidden dangers.This study demonstrates the reliability of the GPR in detecting structures and defects of ancient walls,there by providing technical support for the structural protection of the ancient Great Wall.

In the past two decades, high-sensitivity ring laser gyroscopes have demonstrated the potential of rotational observation data in global seismology. Commercial fiber-optic three-component rotational seismometers have heralded a new development phase of rotational seismography. Field experiments for high-sensitivity portable fiber-optic rotational seismometers in China remain in the initial stage, whereas their relevant data analysis results have been obtained internationally. This study elucidated the co-located observation experiments on six components (6C, including three components of translational motions and three components of rotational motions) of an active source and a natural earthquake, involving experimental schemes, implementation steps, and subsequent data analysis. Moreover, this study revealed the primary factors influencing the experiment results by comparatively analyzing the similarities and differences of experiments. Fiber-optic rotational and conventional seismometers need to be fixed on the same rigid panel to ensure the consistency of received signals. Besides, proper ground coupling and burial processing contribute to high-quality experimental data. The experimental results indicate that water bodies will affect surface wave manifestation and P-wave clarity. These findings, enriching the practical experience in seismic rotational observation experiments, serve as a reference for the design of subsequent rotational observation experiments, thereby assisting in completing the experiments and obtaining higher-quality data. In terms of data application, this study optimized and substantiated the feasibility of the preprocessing scheme, with the backazimuth calculation accuracy improved by 58.8° and 50° at the two active-source measuring points, and by 24.1° and 29.4° at the two passive-source measuring points. The application of six-component seismic data from a single seismic station suggests that additional observation of rotational components can acquire more seismic wavefield information, thus the observation of rotational components can be employed to enhance the utilization of China's massive seismic observation data. Overall, fiber-optic rotational seismometers broaden the boundary of seismic monitoring technology, boost seismology research, and create new possibilities for future earthquake research.

After a disposal repository for high-level radioactive waste operates, the near-field surrounding rocks will be long in a thermal-hydrological-mechanical coupling environment. Therefore, their mechanical and permeability characteristics are crucial to the performance evaluation of the disposal repository. The surrounding rocks of the Beishan preselected area for the disposal of high-level radioactive waste in China are typical sparsely fractured granites, whose creep characteristics are directly related to the long-term safety of the disposal repository. Using water jet and wire cutting techniques, along with fracture surface blocking and combined sealing at rock sample ends, this study addressed the challenges of the sample preparation and sealing of fractured granite in thermal-hydrological-mechanical coupling triaxial tests. Based on this, multi-loading triaxial creep tests were conducted. The test results indicate that under the condition of multi-field coupling, the triaxial creep strength of the fractured granite was approximately 80% of its triaxial strength. Creep deformation increased with the axial load level, with lateral creeps more pronounced than axial creeps. For the compacted and crack propagation sections of the rock samples, both the axial strain rate and permeability decreased initially and then increased. In the case of consistent osmotic pressure difference, a higher osmotic water pressure within fractures would lead to decreased peak strength of the rock samples and result in greater lateral creep deformation.The results provide scientific support for the site selection, surrounding rock evaluation, engineering design and construction of the repository.

The spectra of high-order pseudo-random electromagnetic signals encompass all the frequencies required for exploration engineering, it has the characteristics of enhancing work efficiency and strong anti-interference capability, and has been applied in electromagnetic exploration in urban environments. This study extracted effective information from high-order pseudo-random signals in the electromagnetic survey conducted in areas with strong powerline interference within the special exploration area of the Phase I engineering of the Jinan Urban Rail Transit Line 8. To efficiently extract high-quality effective information, an envelope assessment algorithm was combined with high-order pseudo-random signals. Specifically, the actual signal interference was accurately estimated by analyzing the spectral envelope values. This allows for screening received signals, thus further mitigating the impacts of powerline interference and its harmonics. As a result, more effective frequency and geoelectric information were obtained, providing abundant effective electromagnetic data for subsequent inversion and interpretation. The novel method serves as a technique for effective information extraction for future electromagnetic sounding in a complex urban environment.

Effectively identifying the stratigraphic and landslide structures in landslide-prone areas is significant for disaster prevention and mitigation. By investigating the landslides in the Xuelang Mountain scenic spot in Wuxi, this study analyzed the differences between two-and three-dimensional inversion using the high-density resistivity method. Accordingly, this study explored methods for eliminating the banded effect in the three-dimensional inversion, performed three-dimensional resistivity inversion under the constraints of high-precision surface elevation data and borehole-derived prior information, and constructed a three-dimensional geological model for the study area. The results indicate that three-dimensional resistivity inversion enjoys distinct advantages in complex landslide surveys. The banded effect can be effectively suppressed by optimizing the grid spacing, damping coefficient, and filter parameters for inversion. Furthermore, the terrain-induced impacts and the multiplicity of solutions of the inversion can be significantly reduced using constraints of refined terrain data and prior information, thus improving the resolutions of stratigraphic boundaries and landslide structures. Through three-dimensional resistivity inversion and geological modeling, this study determined the three-dimensional stratigraphic structure, along with the spatial distributions of the landslide bodies and sliding surfaces, and investigated landslide mechanisms, providing important data for the survey and control of landslides in the study area.

In response to the increasing demand for large-scale field seismic acquisition, this study developed a low-cost multifunctional nodal rotational seismometer (RBWL) with a micro-electro-mechanical system (MEMS) sensor, considering the functionality, economic feasibility, and the ease of arrangement. The RBWL employs a low-cost and low-power MEMS sensor to acquire seismic signals, involving three-component translational motions (T_x,T_y,T_z) and three-component rotational motions (R_x,R_y,R_z). To reduce the impacts of environmental factors on measurements, the system of the RBWL automatically records real-time information including temperature and attitude while performing compensation correction on the measurement results. For real-time monitoring and data transmission at acquisition nodes, the system establishes a data transmission link integrating 4G, cloud, and client, with the measured maximum data transmission rate up to 100 Mbps. The testing of H/V spectral ratios verifies the system functions and principal performance parameters of the RBWL and its effectiveness in engineering physical exploration.

The geomagnetic field is a vector field in space. However, traditional marine magnetic surveys focus on geomagnetic field intensity, failing to fully acquire and utilize rich information about the geomagnetic vector field. Given this, this study developed a towed marine geomagnetic vector measurement system. This system was designed to operate in dynamic marine conditions and ultimately acquire geomagnetic vector field data within the geographical coordinate system. Through sea trials of the system, grid line and repeat line measurements were obtained. After preprocessing the collected data, the measurement accuracy of repeat lines and crosspoints was better than 6.7 nT and 6 nT, respectively. The results of the sea test indicate that the measurement system has the preliminary ability to measure the geomagnetic vector field at sea, and it can be applied to geomagnetic field measurement tasks near or far sea, obtaining richer geomagnetic field information.

The method of structural superimposed halo to find blind ore is a new method to find blind ore, which is based on the study of the theory of primary halo to find blind ore-the axial zoning of primary halo, and puts forward two new theories of ‘primary superimposed halo theory’ and ‘structural superimposed halo theory’. The accuracy of blind ore prediction by superimposed halo of structure is determined by the correctness of prediction marks and indexes. Based on the summary of seven common signs of structural superimposed halos in the prediction of deep blind ore deposits in more than 100 hydrothermal deposits, four important quantitative qualitative prediction signs are upgraded to quantitative prediction indicators. The structural superimposed halo prediction signs and indicators of 17 different combinations of accurate prediction of blind ore and discrimination of ore body denudation degree in the deep and periphery of the mining area are described in detail, and a practical ideal model of structural superimposed halo for predicting blind ore and discriminating ore body denudation degree is established. The common prediction signs and indicators of the model have important guiding significance for the prediction of deep blind ore in typical hydrothermal deposits, and have achieved remarkable prospecting results in more than 100 mine applications.

The Salt Lake geothermal field in Yuncheng City, Shanxi Province, China lies beneath a densely populated urban area, posing significant challenges to further geothermal exploration and extraction. Based on the distribution of geothermal gradients in the geothermal field, which are higher in the southwest and lower in the northeast, a NE-trending microtremor survey profile was arranged in the southern part of Yuncheng City, aimed at investigating the deep geothermal reservoir structure and NW-trending structures in the geothermal field. The 2D velocity structure profile reveals a pronounced low-velocity anomaly in the eastern part, which is supposed to be induced by the fault fracture zone formed by multiple NW-striking tensional faults. Spatially, this concealed fault zone roughly corresponds to the low-geothermal gradient anomaly in the northeastern Salt Lake geothermal field, suggesting that this fault fracture zone might facilitate the rapid infiltration of cold surface water, thereby lowering the temperature of deep rocks in the northeastern part, leading to the formation of a large-scale low-temperature anomaly zone. Additionally, the faults identified by the microtremor survey can be traceable and confirmed in a controlled source reflection seismic profile in the study area, demonstrating the complementary nature of the two methods. This study further reveals the deep geothermal structures of the Salt Lake geothermal field based on previous efforts. This study provides more valuable bases and guidance for future exploration and resource evaluation of geothermal fields in the region while also demonstrating the effectiveness and superiority of the microtremor survey method in research on urban geothermal resources.

This study aims to improve the seismic exploration effects in the Upper Paleozoic strata of the Yin'e Basin.With the Juyanhai depression in the western Yin'e Basin as an experimental area,it investigated the previous seismic acquisition characteristics and current data processing techniques of the area.Through field seismic acquisition experiments and data processing research in the laboratory,it explored and summarized the seismic exploration techniques for the Upper Paleozoic strata in the Yin'e Basin.Key findings are as follows:(1)The combination of shot holes and seismic vibrators is recommended for seismic excitation in the area according to local conditions;(2)The receiving array length takes precedence over the receiving density;(3)Targeted processing techniques including anisotropy processing,spectral-constrained deconvolution,and wedge transform adaptive denoising can effectively improve the quality of deep seismic imaging.This study provides a reference for relevant research in similar areas.

The static elastic parameters are crucial for shale oil and gas production and fracturing through water injection. Under stress effects, anisotropy exerts significant impacts on the dynamic and static elastic characteristics of shales. Investigating the dominant factors and mechanisms controlling reservoirs' dynamic and static elastic characteristics is a burning key scientific problem in shale oil and gas production and fracturing through water injection. Based on triaxial compression tests combining mechanics and acoustics for shales under different pressurization methods, this study delved into the impacts of anisotropy on the compressional/shear wave (P-and S-wave) velocities and macromechanical properties of shales, and the response patterns of dynamic and static elastic characteristics of shales. The results are as follows: (1) With an increase in the pressure, the dynamic and static Young's moduli of shales increase at a gradually decelerating rate, finally tending to be stable; (2) At certain bedding angles, the dynamic and static Young's moduli are positively correlated, with the former higher than the latter, whereas the dynamic and static Poisson's ratios manifest a subtle correlation; (3) The dynamic and static stiffness coefficients of shales increase with the confining pressure. The P-wave-related dynamic stiffness coefficients C₁₁ and C₃₃ display more significant changes than the S-wave-related dynamic stiffness coefficients C₄₄ and C₆₆; (4) The dynamic and static anisotropies of shales also increase with the confining pressure. The results of this study reveal the response mechanisms of the dynamic and static elastic characteristics of shales while providing crucial mechanical parameters for the exploitation and hydraulic fracturing of shale oil and gas reservoirs, thus demonstrating significant scientific research value.

Over the past century, electromagnetic exploration technology has evolved from direct current resistivity and induced polarization methods to a comprehensive geophysical system. Yet, in China's new mineral exploration phase, challenges like deep-mining needs, cultural noise, and weak 3D interpretation limit traditional methods. High-power-ultrahigh-power electromagnetic technology, by boosting transmission current, combats these issues. It enhances detection depth, enables 3D exploration, and drives technological and application innovation. This paper reviews the development of high-power-ultrahigh-power electromagnetic instruments and current research. It emphasizes that technologies like true 3D full-waveform IP collection and inversion, tensor CSAMT collection and inversion, and multi-parameter joint inversion of time-and frequency-domain EM methods can strengthen deep-target detection. Future research should tackle anisotropic 3D inversion, full-domain inversion with a field source, and extracting polarization and magnetization rates under complex constraints. These advances will propel electromagnetic methods toward greater depth, precision, and intelligence, supporting China's renewed mineral exploration efforts.

Post-stack fault recognition is typically performed based on structural attributes, which, however, frequently exhibit unclear characterization of fault contacts and poor fault continuity. Deep learning can characterize middle- to large-scale faults accurately but has a limited capacity to characterize small-scale ones. This study developed a multi-scale fault characterization algorithm using amplitude gradient clutter based on synchrosqueezing generalized S-transform (SSGST). First, seismic data were decomposed into single-frequency data volumes across different frequency bands in the time-frequency domain. Then, the clutter of the amplitude gradient vectors was computed based on the seismic data volumes of different frequency bands. Finally, multi-scale faults were characterized using seismic data volumes of different frequency bands. The results from both model simulations and practical data demonstrate that the amplitude gradient clutter property derived using SSGST provides can effectively characterize small-scale faults besides large-and medium-scale faults.

The Autonomous Underwater Vehicle (AUV) equipped with a magnetometer conducts underwater magnetic anomaly detection, enabling long-duration and large-scale continuous sampling. It offers advantages such as concealment, high efficiency, high practicality, wide application range, strong maneuverability, and robust endurance. To improve measurement accuracy, synchronous seabed magnetic field data is needed as a reference to counteract environmental magnetic noise. To address this, a submarine optically pumped magnetometer was developed to provide a reference for processing AUV magnetic anomaly detection data.The submarine optically pumped magnetometer consists of a magnetic field measurement unit and an acoustic release unit, capable of high-precision autonomous acquisition of the total magnetic field on the seabed, as well as underwater acoustic release and recovery. The magnetic field measurement unit includes an optical pumping probe, electronic unit, counter, battery pack, and nylon pressure chamber. The acoustic release unit includes an acoustic transducer, acoustic communication board, electro-corrosion decoupler, cement block, buoyancy block, and frame. This design addresses key technical challenges such as miniaturization, autonomous acquisition, and underwater acoustic communication.In 2022, a magnetic anomaly detection test was conducted in the offshore waters of Qingdao. The test results verified the autonomous seabed magnetic field acquisition and the release and recovery functions of the submarine optically pumped magnetometer, providing effective reference data for underwater target detection.

Due to dense buildings and structures and insufficient drilling surveys, the construction of shield tunnels passing through urban karst formations that host dense buildings faces significant risks of surface fracturing and subsidence caused by karst development. Hence, this study employed the microtremor survey technology with strong anti-interference capability in complex environments to address this challenge. Based on the technology, it analyzed the structural characteristics of wave velocities in underground rock formations through the inversion of the apparent shear-wave velocity profile. Combined with geological drilling data, it inferred the bedrock interface, highly weathered unconsolidated formations, and karst cave anomaly zones. Key findings are as follows: (1) The apparent shear-wave velocities in the study area gradually increased from the shallow to deep formations. Formations with wave velocities above and below 300 m/s were inferred to be limestone and Quaternary formations, respectively, with the rock-soil interface at depths approximately between 10~15 m; (2) Seven low-value anomaly zones of apparent shear-wave velocities ranging from 150~240 m/s were interpreted. They were presumed to be unconsolidated formations or karst caves at depths ranging from 8~30 m. Relying on strong anti-interference and high accuracy, the microtremor survey technology can accurately identify the shear-wave velocity structures of underground profiles, lithologic interfaces of formations, unconsolidated formations, and karst cave anomalies. Therefore, the technology is effective in the geological exploration of urban dense building areas with karst development.

As an important part of gravity investigation, the performance tests of gravimeters are required throughout field surveys. In these tests, mean squared error (MSE), accuracy, and root mean squared error (RMSE) are commonly employedto quantitatively describe the test results. The comparison of the theoretical equations for dynamic and consistency tests in specifications on geological surveys, petroleum, and measurement reveals a pronounced confusion in the usage of MSE, accuracy, and RMSE. This issue is observed in the consistent equations forconsistency testsin these specifications. Through investigations into the equations used in the dynamic and consistency tests inthe threespecifications, this study analyzed the differences between mean MSE and RMSE, elucidated the normativity of RMSE relative to MSE, and determined the applicablerange of RMSE. To avoid confusion, it is recommended that accuracy be used for qualitative expression and RMSE for quantitative expression in these specifications.

Dynamic groundwater monitoring provides critical foundational data for the safety assessment of candidate sites for the geological disposal of high-level radioactive waste. However, research has revealed that actual monitoring data frequently contain numerous anomalous values, severely interfering with the accurate assessment of the dynamic monitoring process. Therefore, there is an urgent need to develop an efficient method to accurately identify these anomalous values. This study built a combined model for anomalous value detection of the groundwater level using local weighted regression-based time series decomposition and the minimum covariance determinant (MCD) method. This combined model allowed the MCD method to achieve anomaly detection in more independent residuals. Results indicate that the combined model exhibited higher sensitivity and detection accuracy for anomalous data than the single MCD model. Furthermore, this study established that the threshold of the combined model should be close to the actual proportion of anomalous values to achieve optimal detection results. Besides, this study validated the applicability of the combined model using groundwater level data from boreholes BSQ01, BSQ25, BS35, and BS26 at the new site. The validation results demonstrate that the combined model can accurately identify anomalous values amidst a large volume of data on the normal groundwater level and is applicable to the detection of different types of anomalous events.

Through surface geological surveys, geophysical measurements, borehole investigations, and 3D geological modeling, the deep geological environment of the Shazaoyuan area has been studied. The lithology, structural spatial distribution, rock integrity at depth, and engineering geological characteristics of the Shazaoyuan area have been preliminarily identified. The main findings are as follows: The granite rock mass in the Shazaoyuan area has a large exposed surface, with relatively uniform lithology, primarily composed of biotite granodiorite of the Shazaoyuan superunit, covering an area of about 330 km². The granite body dips outward and extends to a depth greater than 2 km. There are 12 faults developed in three main orientations: North-northwest, near north-south, and northeast, all with steep dips and intersecting the rock mass. Fractures are well developed in the deep part of the granite, mostly with steep dips and filled with minerals such as calcite and clay. Preliminary delineation has identified more than two favorable rock masses in the pre-selected Shazaoyuan area, which may serve as potential candidate sites for high-level radioactive waste disposal facilities.Though the research,it is proved that the Shazaoyan area has favorable geological conditions for screening the high-level waste disposal bank.

As a semi-airbone transient electromagnetic (TEM) platform, drones inherently generate electromagnetic signals that may interfere with the collected transient electromagnetic data. This study investigated the impacts of drone noise on the collected data. Through outdoor experiments and systematic performance testing, this study analyzed the impacts of drone noise under varying rotor speeds, suspension lengths, flight height, and flight speeds. Accordingly, this study proposed methods for suppressing drone noise, such as determining the optimal suspension length and incorporating shielding layers. The study was conducted using the KWT-X8L-25 octocopter drones, but the research methodology and philosophy are also applicable to other drone models, thus serving as a reference for the selection of semi-airborne TEM platforms.

Currently,seismic data acquisition of in-seam waves is typically performed using mine-orientated digital seismographs combined with moving coil geophones.However,such conventional data acquisition system suffers from narrow frequency bandwidths and bulky equipment.To improve data quality and construction efficiency,this study designed a single-channel seismograph for in-seam wave exploration by incorporating a microelectromechanical system(MEMS) accelerometer,with the advantages of wide frequency bandwidth and miniaturization,into the acquisition card.The developed seismograph allows for independent excitation and distributed acquisition,with frequency bandwidths ranging from 1 to 800 Hz,resulting in improved data quality.A single seismograph weighs only 0.52 kg,and the integrated design completely eliminates the constraints of cables.The total weight of the 100 channel observation system is only 52 kg,representing only 10% of the weight of a distributed seismograph and 25% of that of a nodal seismograph system.The reduction in the overall weight contributes to both reduced transportation costs and enhanced construction efficiency.

This study aims to enhance the measurement accuracy of the electric field by reducing the range shifting and background noise of electric field sensors in the electromagnetic detection system. First, it ascertained the design requirements of electric field sensors by investigating the mechanisms of the range drift and background noise. Second, it established the Ag-AgCl-based preparation process for graphene-based stable electrolyte gel. Third, it optimized the multi-cell multi-contactor electrode structure based on polymeric microporous membranes. Finally, it developed a graphene-based electric field sensor characterized by low range drift and background noise. This sensor can retard internal ion diffusion by leveraging the ion retention ability of graphene and the multi-cell structure composed of reaction, transition, and buffer zones. Consequently, the range drift caused by changes in the ion concentration is reduced. The internal and contact resistance of this sensor can be reduced through the conductive ability of graphene and the enhanced contact with the ground via multiple contactors, respectively, thereby reducing the sensor's background noise. The graphene-based electric field sensor developed in this study shows range drift not exceeding 20 μV/24 h, and background noise not above 25 nV/√Hz. This sensor was applied to a 24 h field magnetotelluric sounding test conducted in the Duobaoshan area, Heilongjiang Province, yielding high-quality electric field data in the frequency band of 0.000 125~320 Hz, with the apparent resistivity phase curve aligning with the result of commercial electrodes. Therefore, the graphene-based electric field sensor proves effective in fieldwork.

Survey grid layout is a preliminary task of geophysical and geochemical exploration. The widespread use of handheld GPS has greatly facilitated navigation and positioning in small-to medium-scale geophysical and geochemical field surveys. This study, based on coordinate transformation theory, presented a method for generating large numbers of GPS waypoints for both regular and irregular survey grids for geophysical and geochemical exploration. Furthermore, an associated software program was developed. The software enjoys simple interfaces and convenient operations, enabling the quick generation of survey grids suitable for applications such as gravity, magnetic, and resistivity surveys, soil surveys, and stream sediment surveys. Therefore, this software can be used for field navigation.

Multiple types of non-layered and irregular hydrocarbon reservoirs have been found in the deep carbonate strata within the Tarim Basin. These carbonate reservoirs, different from layered reservoirs, are geological bodies with limited lateral bodies in at least one direction. The observed seismic reflected wavefield is a composite field composed of reflected and diffracted (scattered) waves formed by layered strata and non-layered and irregular geological bodies. The three types of wavefields exhibit different morphological characteristics in different datasets. Based on the differences in wavefield morphology, this study, using a technique for separating layered and random wavefields based on an image-guided, sparse-constrained parabolic Radon transform in the frequency domain, decomposed high signal-to-noise-ratio data of complex reflected wavefields, which had undergone migration processing or not, into a reflected wavefield with infinite lateral extent and a diffracted (scattered) wavefield of irregular geological bodies with limited lateral extent. This technique provides a foundation for the direct prediction and investigation of irregular reservoirs and has been successfully applied in both the Tarim and Ordos basins.

The inversion of petrophysical data can image the microscopic fracture structures inside rocks, revealing the evolutionary patterns of fractures within rocks and soil with changes in external environments. Hence, it is an intuitive and reliable method for investigating the mechanisms of deep geotechnical disasters. This study presented a petrophysical data acquisition system and resistivity-based forward modeling and inversion algorithms. Based on the above, this study conducted numerical simulations of 2D and 3D inversion imaging of petrophysical data. As indicated by the numerical simulation results, 2D inversion imaging can characterize millimeter-scale rock fractures with high/low resistivities, whereas 3D inversion imaging can accurately locate and effectively identify millimeter-scale fractures and vugs with high/low resistivities. Moreover, data measurement and inversion imaging were conducted on rock samples subjected to microwave-induced fracturing in three states: heated sandstone before failure, sandstone heated to a molten state, and molten sandstone in a cooled state, preliminarily revealing the variation patterns of sandstone fractures under microwave heating. Overall, this study provides a novel method for exploring the mechanisms of deep geotechnical disasters.

Recommendation system algorithms, having recently garnered significant attention in the field of digital Earth science, are expected to be widely applied in metallogenic prediction. Traditional metallogenic prediction studies fail to fully mine the various types of semantic information in massive geoscience data. The deep interest evolution network (DIEN), as a recommendation system algorithm, can fully mine semantic information to predict user preferences. Therefore, this study employed the DIEN model as the prediction model and the semantic information extracted from bedrock interpretation as the ore-controlling elements according to the database provided by the Western Australian government. The model was trained to perform metallogenic prediction for the study area. The prediction results indicate that 92.95% of uranium ore occurrences fell within the medium-high probability zone in the prediction map, with some unknown zones also showing high prediction probabilities. After removing known uranium ore occurrences in some zones, the retrained model still yielded medium-high prediction probabilities in these zones. The results suggest that the DIEN can effectively mine semantic information in metallogenic prediction studies, and the DIEN model exhibits strong predictive capacity for the study area, providing a novel approach for metallogenic prediction studies.

The cepstrum decomposition technology for seismic signals,recently developed for hydrocarbon detection,can highlight weak fluid information in some specific frequency bands of broadband seismic signals.This study explored the cepstrum decomposition technology for seismic signals using Fourier transform(FT)- and wavelet packet transform (WPT)-based cepstrum.Moreover,the technology was applied to the ultradeep carbonate reservoirs in the Shunbei area for hydrocarbon detection.A comparative analysis was conducted on the characteristics of common cepstrum profiles and conventional common frequency profiles.Furthermore,a detailed comparative analysis was conducted on the characteristics of the first- and second-order common cepstrum profiles of FT- and WPT-based cepstra.On this basis,the hydrocarbon detection effects were compared between FT- and WPT-based cepstra.The processing results of actual seismic data show that compared to the conventional spectral decomposition technology based on wavelet transform,the cepstrum decomposition technology manifested higher spatio-temporal resolution,providing more detailed information. Contrasting with FT-based cepstrum decomposition,WPT-based cepstrum decomposition provided a more accurate interpretation of gas-bearing properties through the seismic amplitude anomaly profiles.

Underground research laboratories (URLs) for the geological disposal of high-level radioactive waste serve as critical facilities for verifying the safety and suitability of the sites of potential disposal repositories and for developing disposal technologies. URLs are irreplaceable in many aspects such as the siting and system design of potential disposal repositories, the development of the theories and technologies for disposal engineering, the safety and characteristic assessments, full-scale field tests, and on-site demonstration. This study highlights the definition, classification, and functions of URLs and categorizes existing primary URLs both in China and abroad. URLs are generally categorized into general URLs (first generation) and site-specific URLs (second generation). The construction of disposal repositories in China has progressed from national, regional, and site screening to site evaluation and to URL construction. The authors of this study proposed the concepts of "site-specific URLs" and "third-generation URLs" in 2010 and 2014, respectively. Furthermore, the Beishan URL-the world's first site-specific URL for the geological disposal of high-level radioactive waste-has been built. This study introduces the siting process, planning, positioning, and functions of the Beishan URL, as well as the functions of primary scientific experiments and main field experiments conducted during its construction. The results of this study serve as a guide for future siting and R&D of disposal repositories.

Single crosshole tomography features a multiplicity of solutions, rendering it challenging to accurately identify karst anomalies. Given this, this study introduced color fusion technology and tested its effectiveness in the inversion of three types of crosshole seismic CT data using numerical simulations: elastic wave travel time CT, elastic wave attenuation CT, and electromagnetic wave attenuation CT. A field experiment on karst identification using comprehensive crosshole CT data reveals that the color fusion technology can effectively enhance the accuracy of karst identification. The results of this study provide an effective method for comprehensive crosshole detection and interpretation for karst exploration in foundational projects such as oil and gas pipelines, bridges, and tunnels, holding great significance for improving the exploration accuracy of karst.

Many cities or urban residential areas in central and western China reside in alluvial plains formed from piedmont alluvial fans. Hence, revealing the stratigraphic architectures and stability of alluvial fans holds critical significance for urban construction planning and rational land use. The alluvial fan in the eastern piedmont of the Liupan Mountains hosts the urban residential areas and villages of Guyuan City, with a dense population. Moreover, the alluvial fan develops several event deposits recording the activity of the alluvial fan under tectonic movements and climatic changes. Through field geological survey, optically stimulated luminescence dating, controlled source audio-frequency magnetotellurics (CSAMT), and conventional radon measurement, this study revealed the stratigraphic architecture of the alluvial fan and its two-phase event deposits (~43.33 ka B.P. and 22.92~20.72 ka B.P) since the Late Pleistocene. As indicated by the CSAMT and conventional radon measurement results, the alluvial fan still exhibits high activity under the influence of the Haiyuan and Qingshuihe faults. The results of this study provide fundamental data for crustal stability assessment, prevention and control of geologic hazards, and engineering construction in the Liupanshan area.

The Hexi Corridor and northern Qilian region, adjacent to the Beishan underground research laboratory (URL) for the geological disposal of high-level radioactive waste, exhibit complex seismic environments characterized by frequent strong earthquakes. The Beishan URL, featuring a complex underground structure consisting of three vertical shafts and a spiral ramp, displays significant large-scale spatial distribution characteristics. Investigating the seismic response characteristics of the underground structure group holds great engineering significance for the subsequent assessment of crustal stability at the site. Based on the design of the URL, along with existing physical and mechanical parameters of surrounding rocks, this study established a fine-scale three-dimensional finite element model of the rock mass-underground structure system. Using this model, this study investigated the impacts of key faults on the near-field seismic safety of the URL. The results indicate that traditional seismic attenuation relationships are difficult to consider near-source effects, such as finite fault effects, fracturing directivity effects, and hanging wall effects. In contrast, the stochastic finite-fault method can effectively consider these near-field ground shaking characteristics. The target site exhibits hard granite bedrock, and the response spectra of the earthquakes induced by near-field seismogenic faults, received at the site, display pronounced high-frequency components. Furthermore, the ground shaking of the underground cavern group, caused by the irregular structure of the URL, presents significant spatial variability, with the rock mass softening zone exhibiting a notable accumulation of peak ground acceleration. This zone should be avoided in engineering applications. This study offers a basis for seismic safety analysis for the future site selection and evaluation of the disposal repositories of high-level radioactive waste.

The Yimin Formation hosts shallow and stable coal seams, which are rich in coal resources and suitable for open-pit mining. To ascertain the distributions of coal seams in the Yimin Formation and reveal the coal accumulation patterns, it holds critical geological significance to identify the provenance setting and coal-forming environment using geochemical methods. This study systematically collected coal samples from drilling cores in the study area for testing and analysis of coal quality.Furthermore, this study reconstructed the paleogeographic information and sedimentary environment during the formation of coal seams for comprehensive research. The results show that:(1) The coal seams of the Yimin Formation are primarily composed of lignite, with durain being the dominant component, followed by fusain. Their coal samples exhibited average vitrinite reflectance (R₀) of 0.37%, average oil content of 7.66% in raw coal, and average total sulfur content of 1.32%; (2) The average CIA value of 58.45 suggests that the source area experienced primary to moderate weathering. The average w(Si)/w(Al) ratio of 2.72 indicates that minerals in the coal originated from terrestrial argillaceous sediments. The ash index (K) of 0.34 implies that the coal seams formed in a low-level peat swamp environment. The w(Sr)/w(Cu), w(Sr)/w(Ba), w(Mg)/w(Al) (m), and w(Ca)/w(Fe) (n) ratios signify warm and humid paleoclimate, significant evaporation, and high salinity of ancient water bodies during the coal seam sedimentation stage. The Sr, Ba, and w(Ba)/w(Ga) values denote that the coal seams resulted from continental sedimentation. The w(V)/[w(V)+w(Ni)], w(V)/w(Cr), w(Ni)/w(Co), and w(V)/w(Sc) ratios demonstrate that the coal seams formed under anoxic reducing conditions. This study posited that the early sedimentary stage of the Yimin Formation saw the reduced continental faulted basin, humid climate, and lake siltation, forming a peat swamp environment in the deltaic plain, thus creating favorable conditions for coal generation and accumulation.

Currently,velocity spectrum analysis methods widely used for ground-penetrating radar(GPR) signals mostly construct velocity spectra by superposing the amplitude energy of coherent signals to estimate electromagnetic wave velocities in subsurface media.In the case of multiple peaks and troughs in signal wavelets,velocity spectra constructed using these amplitude-based methods display multiple energy clusters,adversely affecting the identification,picking,and velocity estimation of subsequent energy peaks.Hence,this study proposed a method for estimating electromagnetic wave velocities in subsurface media based on common-offset GPR signal envelope and 3D velocity spectrum analysis.By scanning the signal envelope of hyperbolic diffracted waves in the GPR profile,the proposed method constructed the 3D velocity spectra of superimposed energy varying with zero-offset two-way travel time,test velocity,and measuring point position.Moreover,it extracted the slices of 2D velocity spectra according to the positions of hyperbolic vertices in the 3D velocity spectra.On this basis,the test velocities corresponding to the energy peaks in the slices of 2D velocity spectra were picked as the electromagnetic wave velocities in subsurface media.The numerical test results show that compared to the amplitude-based methods,the signal envelope-based 3D velocity spectrum analysis method obtained velocity spectra characterized by fewer continuous energy clusters,more concentrated energy,and minor velocity estimation errors,thus more effectively constructing the velocity model with inverse-time migration.

The definition of avoidance distance between deposition hole and water conducting fracture is an important basis for evaluating the site suitability of the high-level waste disposal repository,and it is also one of the key contents of the design of high-level waste disposal repository. In this paper, the site of the Beishan underground research laboratory is taken as the reference site for geological disposal of high-level radioactive waste. This paper established a computational model for the release and migration of radionuclides after closure of repository by GoldSim. Then, the avoidance distance between deposition hole and water conducting fracture in intact rock was analyzed by the method of Monte Carlo stochastic simulation. The results show that a 80% hydraulic conductivity value of the granite in the study area is less than 1.0×10^-9 m/s under the existing conditions, and when the hydraulic conductivity value of water conduction fracture is set to 1.0×10^-6 m/s, the corresponding avoidance distance is less than 0.5 m. The smaller the permeability coefficient is, the smaller the corresponding safety avoidance distance is. The analysis of the results shows that the avoidance distance between the deposition hole and water conducting fracture can provide a feedback guidance for the site selection and design of the disposal repository.

In structural confirmation for oil and gas exploration, ascertaining the distributions of faults remains a challenge and priority in seismic data interpretation. The most complex fault combinations can be observed in strike-slip fault systems. This study investigated the Erbatai area that hosts a complex Luntai strike-slip fault system in the Tarim Basin. First, the background noise was reduced using the dip angle plus azimuth scanning and the structure-oriented filtering. Then, a multi-level nesting technology was developed by integrating attributes like coherence cube, ant-tracking attribute, and maximum likelihood. Using the technology, this study identified and statistically analyzed 41 faults in the Erbatai area for their geometric development characteristics, including strike, dip, dip angle, and fault throw. Furthermore, this study determined the complex fault combinations within the strike-slip fault system. The findings indicate that the Erbatai area develops a dominant nearly EW-trending strike-slip fault zone and a NE-trending secondary fault zone. These faults are extensional fractures caused by left-lateral torsion, manifested as right-stepping en echelon normal faults. Overall, this study can be referenced for assessing structural hydrocarbon reservoirs in the Erbatai area.

Areas with low exploration degrees in the Tarim Basin exhibit intricate seismic-geologic conditions and extensively developed multiples.The internal multiples generated by strong reflection interfaces involving Paleozoic gypsum rocks undermine the imaging of the Ordovician stratigraphic information,resulting in vague images for Ordovician fractured-vuggy carbonate reservoirs and thus affecting stratigraphic interpretation.Accurate prediction and suppression of internal multiples in the Yubei area is challenging,thus restricting the deployment of oil and gas exploration in the area.The conventional prediction method for internal multiples is computationally intensive and ineffective.Hence,this study proposed an internal multiples suppression technique combined with the modeling method and adaptive matching subtraction.Based on the principles of internal multiples prediction and the forward modeling results,the proposed technique takes the main reflection interfaces generating internal multiples as the model layers and follows the approach of layer-by-layer prediction and suppression.Finally,it employs adaptive matching subtraction for the suppression of internal multiples.As demonstrated by the processing results of actual data,the proposed technique can effectively predict and suppress the dominant internal multiples to eliminate their interference effects.It solves the problems of layer-crossing phenomenon and flat formation occurrence,improving the imaging accuracy of formation structures,faults,and fractured-vuggy reservoirs.