Grounded-source transient electromagnetic method (TEM) has many advantages such as deep exploration, flexible arrangement in rough terrain and high working efficiency. Recently it has got much attention and a series of new methods are available, ranging from surface to airborne and borehole method. In this paper, the authors review the research history of long-offset TEM (LOTEM), short-offset TEM (SOTEM), multi-channel TEM(MTEM), grounded-source semi-airborne TEM and grounded-source surface to borehole TEM, and summarize their research status in forward modeling, system design, inversion, imaging and field working. The results show that, as a well-developed grounded-source TEM, LOTEM has accumulated many research achievements. Although some progress has been made, the researches on other grounded-source TEMs are still in a primary stage and still need further improvement. Valuable research results in LOTEM, for example, noise suppression technology, high dimensional inversion and point interpretation, can be introduced to these newly developed electromagnetic methods, which can help provide solutions for high working efficiency and high resolution deep exploration.

Studying the occurrence of natural gas hydrates (NGHs) is of profound significance for NGH exploration. The evaluation of the NGH saturation mainly relies on the Archie equation using the electrical parameters of rocks. The key to accurately calculating the NGH saturation is to select corresponding values of rock electrical parameters for different geological environments, especially the porosity index (m) and the saturation index (n). However, it is still a challenge to select the optimal m and n values for NGH evaluation in resistivity logging. To ascertain the relevant resistivity regularity of NGHs and the determination method of rock electrical parameter values in the Archie equation, this study systematically reviewed relevant references and summarized the resistivity influencing factors of NGHs. Moreover, this study analyzed the influencing factors for the accurate evaluation of the NGH saturation based on the Archie equation. Accordingly, this study generalized the resistivity characteristics of NGH-bearing sediments and proposed the application research direction of the Archie equation.

It is more difficult to predict the low porosity and low permeability tight reservoir than to predict the regular reservoir.The authors therefore tentatively applied kernel principal component analysis and support vector machine,called KPCA-SVM model,to solve this problem.Through the polynomial kernel function of the KPCA,the model can obtain the nonlinear feature extraction.Then the Gaussian kernel function in the SVM is chosen to perform optimization again.Finally,reservoir identification is implemented in the SVM.As the model incorporates the advantages of kernel function,principal component analysis and support vector classification,it can better solve the problem of nonlinear small sample,eliminate the noise of the data and reduce the dimension without missing valid information.In addition,it can achieve the prediction function quickly and accurately.The model was employed to predict the reservoir in x856 well block,which belongs to Xu2 member gas reservoir of the Xinchang gas field.The prediction results show the superiority of this model,which can be used as an optional method in tight reservoir prediction.

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).

1995 was the last year of China's Eighth Five-Year Plan.Over the past five years,oil and gas geophysical work has developed steadily;techniques such as three-dimensional seism,reservoir description and transverse prediction geophysics have made considerable progress;three-dimensional seismic pre-stack depth offset processing has begun its application;more importance has been attached to direct oil and gas goophysical prospecting technology; some problems such as nonlinear inversion,viscosity and elasticity,double phase and anisotropic media have become focuses of the research.Geophysical work on solid resources has not yet got itself out of the depression;nevertheless,the related techniques remain in progress Our own sofware and hardware system attached to transient electromagnetic method has been basically formed, and gratifying achievements have been acquired in the aspects of distributive type multichannel synchronous electromagnetic system and processing- interpretation working station of integrated electrical method.The increasing market demands for engineering and environmental geophysics have promoted the development of shallow geophysical technique,which,however,still needs the guidance and support from systematic key research projects.

Dual-Probe Heat-Pulse method was modified for application of determining in-situ thermal conductivity of marine

sediments. It was crucial to process DPHP data and extract thermal conductivity from these data. A processing flow was

established based on measured data with consideration of the specific measurement situations at sea. The pre-processing

procedure, including filtering, trimming, and ambient temperature fitting and eliminating, was suggested in order to obtain a

temperature response curve of heat pulse, which was then utilized to calculate thermal conductivity. Besides the K-B model, a

simplified model to calculate thermal conductivity was advanced which has advantage in reducing operation and cumulative error.

By comparing the two thermal conductivity calculation methods, extremum method and fitting method, it was proposed that the

extremum method will be the first choice so long as the sampling rate was high enough.

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.

This paper has summed up the progress of the ERI method over the past decade of years as well as its future development trend in the following aspects: ① A comparison of the performances of the main ERI instruments used at present shows that the ERI instruments tend to develop in the multi-channel, multi-parameter, multi-functional, high-power direction; ② ERI measurement environment has changed from surface measurement to water surface, underwater and cross-hole measurements, with the last three kinds of measurements analyzed in this paper; ③ On the basis of analyzing ERI data processing method and inverse development status, this paper describes three-dimensional and four-dimensional inversion theory of ERI with practical examples; ④ ERT applications are summed up, and several new applications are introduced. It is concluded that, with the improvement of the probing depth and observation precision as well as the diversification of the observation models, the application field of ERI will become broader and broader, and this technique will surely have wide development prospect.

This paper deals with the standing wave resulting from the interference of the reflection electromagnetic wave when the electromagnetic wave is transmitted and perpendicular to the strata. The conditions of antinode and node formed on the ground are also discussed. According to the equation deduced by the author, the thickness of the strata and the relative sizes of the electromagnetic parameters in the media on the two sides of the bottom interface of the strata can be determined by measuring the frequency of the antinode. It is also pointed out that at least four natural electromagnetic wave sources can be used in geophysical exploration based on the electromagnetic standing wave method.

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.

This paper deals with three gravity satellites, namely CHAMP, GRACE and GOCE. Satellite gravity data are widely used in such fields as the recovery of the earth's gravity field, the land water storage, the study of the geoid change, the elastic thickness, the crustal thickness, the gravity variance before and after earthquake and the crustal movement. Lots of successful and valuable research results were obtained. It is considered that the satellite gravity survey technology is by for superior to traditional gravity survey and will surely have larger application space.

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 conversion of the quantities, units and formulae in electromagnetism between the Gauss System and the International Unit System is rather complicated, and there may occur some errors in the units of some derived quantities. For this, the author has made some explanations in this paper.

In the light of the pulse width of the radar wave, this paper deals with the difference and the relationship between the vertical resolution and the transverse resolution of the ground-penetrating radar, indicates the influence of the noise upon the resolution and, with practical examples, points out that the digital handling of the signal can greatly improve the resolution of the radar.

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.

This study summarized the progress and major application performance of gravity and magnetic techniques for onshore hydrocarbon exploration in China in recent years.By combining the research results of the authors,this study elucidated the new progress made in the gravity and magnetic techniques for hydrocarbon exploration from the prospect of acquisition,processing,interpretation,and application and sorted the application performance of these techniques in key fields including deep targets,complex areas,and volcanic rocks.Moreover,this study future analyzed the demand for the gravity and magnetic techniques for hydrocarbon exploration.By combining the new trends of gravity and magnetic exploration techniques at home and abroad,this study proposed the development direction and application prospect of gravity and magnetic techniques for oil and gas in deep strata and igneous rocks in complex areas.The results of this study show that significant progress has been made in gravity and magnetic exploration techniques,which play an important role in supporting the current hydrocarbon exploration.It is expected to develop high-precision and high-density gravity and magnetic exploration techniques and gravity-gravity-electricity-seismic collaborative innovation techniques.

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 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.

Both the controlled source audio-frequency magnetotellurics (CSAMT) and the microtremor survey exhibit promising application prospectsunder strong urban interference. However,single geophysical inversion methods are challenged by a multiplicity of solutions. To achieve the complementary advantages of different geophysical methods, and address the lateral discontinuity of single-point inversion, this studyexplored the quasi-two-dimensional joint inversion of the CSAMTand microtremor survey data. It enabled the joint inversionby introducing a lateral constraint matrix into the objective function for joint inversion and employing the limited-memory Broyden-Fletcher-Goldfarb-Shanno (LBFGS) algorithm. The reliability and effectiveness of the joint inversion were verified using the inversion example of synthetic data from theoretical models. The results show that compared to single data inversion, the joint inversion can effectively improve the accuracy of inversion results, with the resistivity model more consistent with theshear-wave velocity structure. Moreover,lateral constraints can effectively reduce the discontinuity of the physical parameters of adjacentsurvey points. The quasi-two-dimensional joint inversion with lateral constraints enhances the inversion reliability by obtaining more reasonable profile results of physical parameters and structures with the efficiency of single-point inversion.

Magnetotelluric (MT) data collected from offshore areas are generally distorted due to coastal effects, posing challenges in obtaining true subterranean electrical structures. Based on the model of half-space with seawater, 2D electrical isotropy and anisotropy models, and 3D electrical isotropy model, this study analyzed the distortion patterns of MT responses under coastal effects through forward modeling. Moreover, it conducted 2D and 3D inversions of MT data with or without seawater constraints. Key findings are as follows: (1) The initial frequency points of distortion in MT apparent resistivity curves are closely correlated to the distances from survey points to seawater; (2) Compared to MT responses free from coastal effects, the high-frequency sections exhibit increased amplitudes in real induction vectors only at survey points in offshore areas and higher phase tensor ellipticity, whereas the low-frequency sections display expanded influence areas subjected to coastal effects; (3) Excluding seawater constraints, the inversion results show false anomalies in offshore areas and poor reconstruction effects on subsurface anomalies. Considering seawater constraints, the constrained inversion can effectively suppress the distortion caused by coastal effects. Overall, this study will provide a significant reference for the collection, processing, and interpretation of MT data from offshore areas.

Exemplified by the water resource for water supply of Shizong Railway Station on the Nanning-Xunming-Railway line, the present paper describes the techniques for field work, data iaterprotation and drill hold location in the application of electrical sotaling to the prospecting for karst wator.

The geochemistry survey analysis was conducted on the soil samples collected from the Yixing area in 2004, 2009, and 2015 years, and the results show that the pH-value of surface soil varies from 3.53 to 8.86. Specifically, the acidic soils and strongly acidic soil generally distribute in the distribution of hill sandstone strata. The weak alkaline soil generally distributethe in the distribution of limestone strata. In the alluvial lake plain area, most soil is weakly acidic. And it shows the soil parent material and topographic features impact soil PH-values. Comparing with the changes of the surface soil pH-values within the past six years, the result show that there are 49.77% soils with decreased pH-value, the 23.53% soil with increased pH-valua, and 26.70% soils with relative stable PH-value. Due to the impacts of industrialization development on the environment, the acid rain plays an important role in soil acidification. Affected by farming and among others, the pH-value of surface soil in the alluvial lake plain area are lower than those of deep layer soil by around 1.2. The acidification of the surface soil occurs mainly in the tillage layer, the depth is about 30cm, and the bottom soil is basically neutral. From the general point of view, the analytical results of surface soil in the Yixing area show a trend of acidification. Some necessary measures must be done to prevent further deterioration.

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.

In the context of the goals of both peak carbon dioxide emissions and carbon neutrality, scientific and efficient exploration and exploitation of geothermal resources are criticalfor the geothermal industry. To address the commonly concernedtechnical challenges in the exploration of moderately deep geothermal resources, this study investigated the effectiveness of comprehensive geophysical prospecting in the exploration of geothermal resources inthe Linjiadi area, Aohan Banner, Inner Mongolia. Based on the analysis ofthe geological and hydrogeological conditions, this studypreliminarilyascertainedthe geothermal field characteristicsand the hydrochemicalcharacteristics of groundwater in the Linjiadi area. By comprehensively employingcontrolled source audio-frequency magnetotellurics (CSAMT), CSAMT; microtremor survey; radioactive radon survey; this study roughly determined the distribution of strata, magmatic rocks, and fault structures in the study area, inferring the factors controllinggeothermal anomaly areas and hot-water migration.Accordingly, exploration boreholes were arranged, allowing for drilling verificationwith a total length of 960 m. The results show that the comprehensiveapplication of CSAMT and microtremor survey, combined with radioactive radon survey for auxiliary verification, is effective in exploringmoderately deep geothermal resources. This study will provide a methodological reference for geothermal resource exploration in other areas.

The artificial source electromagnetic method is an important technique for deep resource exploration. The key challenge is to improve the depth and precision of detection through innovative technology. The detection mode of electromagnetic methods is evolving from far-field to near-field, and the study of near-source electromagnetic methods has become an international research frontier in recent years. Building on the recent advancements in wide-field electromagnetic methods and multi-channel transient electromagnetic methods, the short-offset transient electromagnetic method (SOTEM) has been further developed and proposed. The distinguishing features of SOTEM are its stronger signals and wider bandwidth, which are advantageous for achieving the detection requirements of greater depth and higher precision. This special issue presents eight articles covering the methods, techniques, software, and applications of SOTEM, providing strong support for the growing need for high-resolution subsurface detection.

With the geochemical multidimensional anomaly system, the development and application of geochemical anomaly structure's 3D visualization have been carried out. Geochemical anomaly structure applied to the deep ore body prediction collects samples from drill core to get geochemical 3D data. So researchers urgently want to explain and map them. The geochemical anomaly structure system has been developed on the platform of MapGIS K9 using 3D visualization and 3D geological model technology. It has not only realized the integrating of data models on the ground and underground but also the integrating of solid models and attribute models. Analyzing geochemical anomaly structures and exploring ore models could be done in this system. The thought and technology for 3D anomaly structure and its application in the Matou mining area of Anhui Province have been elaborated in this paper.

Karst is widely distributed in China. However, geological disasters frequently occur in karst zones due to the fragile geological environment, which seriously threatens the safety of people’s life and property and cause huge economic losses. In this study, the controlled source audio-frequency magnetotelluric (CSAMT) method and microgravity were used to extract residual gravity anomalies through the two-dimensional inversion of pseudosections and multi-scale wavelet analysis. As a result, rock-soil interfaces of karst zones and the development zones of strong karst were well divided; the locations, burial depths, scales, and spatial distribution of karst caves were delineated. As verified by drilling, the rock-soil interfaces and strong-karst development zones determined by CSAMT interpretation were roughly consistent with those revealed by boreholes, and the sizes and burial depths of collapsed karst caves that were delineated by microgravity roughly correspond to those revealed by boreholes of engineering exploration. These results show that the CSAMT combined with the microgravity method can achieve significant effects in the detection of concealed karst collapses and serves as a scientific detection method for the early warning of the prevention and treatment of potential karst collapses and similar geological disasters.

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.

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.

Rock physics lies in the study of the physical properties of rocks related to seismic properties, especially the quantitative study of the relationship between elastic properties of rocks and their seismic properties with various fluid distributions. This relationship is important in the prospecting and exploitation of oil and gas, and hence rock physics is highly praised as a tool for"opening the door to quantitative interpretation". This paper has briefly reviewed the development of the rock physics and described the designing objects of the rock physics analysis system (RPAS). By combining core measurements with well logging and seismic information, RPAS provides a convenient tool for theoretical and experimental analysis. The ideas behind the design and implementation of RPAS are given, and the user's needs are analyzed. This paper describes the framework of RPAS and its concrete functions. Developed by object-oriented programming and Qt, RPAS is characterized by friendly graphical interface and flexible interactive manipulations. It is open and easy to transplant.

It is of great significance to study the data-processing methods of airborne gravity survey, improve the accuracy of data processing and catch up with the advanced world level. In this paper, based on the domestic three-axis stabilized platform airborne gravity measurement system, the authors carried out the research on data processing methods and corresponding software development of airborne gravity measurement and realized the Kalman smoothing algorithm suitable for the stabilized platform airborne gravity data. The platform airborne gravity anomaly was solved for the first time in China. The internal coincidence accuracy reached 0.590×10 ^-5m/s ², the external coincidence (GT airborne gravity measuring system) accuracy reached 0.581×10 ^-5m/s ², and the accuracy of data processing was up to the international advanced level. The results show that the data processing method is feasible, has high precision, and can improve the data-processing technology of airborne gravity survey in China.

Linze County is located at the southwest edge of Zhangye-Minle basin and along northern central Qilian fold belt and has a good prospect for development and utilization of geothermal resources. The authors analyzed regional geological structure and hydrogeological characteristics of the study area and investigated existing geothermal well and preferred working area by the wide field electromagnetic method. Through comprehensive analysis and on the basis of regional hydrogeologic and geophysical exploration results, the distribution characteristics of geological structure and rock mass in the study area were interpreted and inferred, the prospect of geothermal exploration in the research area was analyzed and evaluated. Meanwhile,the "geology-geophysical-geothermal energy" model of geothermal exploration in the study area was preliminarily constructed. This model provides reference and guidance for geothermal exploration in the study area and adjacent areas.

Multi-channel gamma-ray spectrometers are necessary for measuring natural and artificial radionuclides. The core of the multi-channel gamma-ray spectrometers is the multi-channel pulse amplitude analysis, which determines the resolution and analysis accuracy of radionuclides. This study introduces the working principle of a multi-channel pulse amplitude analyzer based on linear discharge and describes the methods for analyzing pulse amplitude and obtaining spectrum peaks. Secondly, this study details the design methods of eight important parts of the multi-channel pulse amplitude analyzer, including the design basis, design idea, and feasible schemes. Finally, this study details the logical sequence diagram of the analyzer, laying a foundation for readers to design a multi-channel pulse amplitude analyzer. Using the working principle, design method, and working logic sequence diagram presented in this paper, as well as modern high technology, readers can develop a new type of modern multi-channel pulse analyzer with uniform channel width, excellent differential nonlinearity, and improved resolution of radionuclides, thus better serving the society using gamma-ray spectrum data with higher energy resolution and high measurement accuracy.

Laochang, Lancang, Yunnan is one of the most important polymetallic mining areas in the southern part of Sanjiang Tethys metallogenic belt. After years of mining, the shallow resources are nearly exhausted. In recent years, granite porphyry and porphyry polymetallic mineralization have been newly discovered in the deep part of the mining area, highlighting the prospecting potential of deep polymetallic deposits. In order to trace the occurrence of deep ore-controlling strata and structures in the study area and help to make a breakthrough in deep ore prospecting, high-power induced polarization method and audio magnetotelluric method were implemented to image the deep structure situated. Results obtained from the inversion of the measured induced polarization and electromagnetic data recuperated the distribution of induced polarization anomalies and the characteristics of deep electrical structure within the study area. Combined with the available regional geological settings, the main conclusions are as follows: The low resistance and high polarization anomalies in the northwest of the survey area are deeply related to the surface ferromanganese, silver manganese, and deep polymetallic mineralization, and the high resistance and high polarization anomalies in the middle and east of the survey area are in good agreement with the deep polymetallic mineralization. The upper Carboniferous limestone and dolomite strata are thick in the west and thin in the east, with the west strata dipping to SW and the east strata overlying the Yiliu Formation of the lower Carboniferous. The concealed granite porphyry dips in NE direction, and the coupling part between its deep 2 300~2 800 m horizontal section and deep fault is a favorable area for deep polymetallic mineralization. Notably, joint interpretation yielded from the high-power induced polarization method and the audio magnetotelluric method applied improved the reliability of deep polymetallic ore detection and provided more information of positioning the subsequent drilling layout.

This paper makes a generalized description of the scientific and technical advances in magnetic prospecting in China, which include such aspects as gro und magnetic survey, acromagnetic survey, marine magnetic survey, magnetism of rocks, paleomagnetism, absolute measurement of geomagnetic field. data pro cessing and interpretation of magnetic anomalies, and development tendency of this field.

With the continuous improvement of exploration degree,more and more attention has been paid to low-range structural oil and gas reservoirs.Current methods for identifying low-amplitude structures cannot effectively eliminate low-frequency structural background information contained in seismic data,and cannot accurately identify low-amplitude structures.In this paper,on the basis of de-frequency reduction,the trend decomposition method was used in the search for structural inflection points,and the low-amplitude structure was graphed. Combined with the wavelet decomposition method,the continuity in the large-scale time-frequency domain is good.The inverse transform finally obtains a low-amplitude structure explanatory diagram that eliminates the low-frequency background of the structure.The practical application in the northern part of E Basin shows that the low-amplitude structure identification method based on de-frequency reduction enhances the local micro-structural characteristics,and also makes up for the influence of structural elevation difference and random factors on low-amplitude structures.The purpose of the complete and detailed map is of great guiding significance for the exploration and development of complex oil and gas reservoirs with low structural amplitude.

There is a lack of selection bases in the geochemical anomaly identification and the reconstruction of the geochemical background conforming to the metallogenic distribution using deep learning algorithms with different network structures. Given this, based on the 1∶200 000 stream sediment data of the copper-zinc-silver metallogenic area in southwestern Fujian Province, this study extracted the combined structural characteristics, spatial distribution characteristics, and mixed characteristics of multiple elements in the samples using three unsupervised deep learning models, i.e., AE, MCAE, and FCAE. Then, these characteristics were used to reconstruct the geochemical background and simulate the metallogenic distribution. The results show that the anomaly areas delineated by the FCAE model were the most consistent with the known copper ore occurrences, followed by the MCAE and AE models. The FCAE, MCAE, and AE models had an area under the curve (AUC) score of 0.80, 0.78, and 0.61, respectively. Moreover, the FCAE and AE models were not sensitive to the change in the convolution window size. These results indicate that when deep learning algorithms are constructed for geochemical anomaly identification, the algorithms based on the extraction of spatial distribution characteristics or mixed characteristics perform well, and those based on the extraction of combined structural characteristics or mixed characteristics have a strong anti-interference ability for the noise caused by the change or inconsistency of the spatial observation scale. This study provides some effective selection bases for constructing geochemical anomaly identification models based on deep learning algorithms.

The measurement of the electrochemical polarization effect of rock (ore) in an AC electric field (i.e., the phase between receiving potential different and transmitting current) using spectral induced polarization (SIP) can provide important information for distinguishing ore from non-ore. Based on the deep research on the key technologies of SIP instruments, this study designs a new synchronous correlation detection technology of weak signals, and accordingly improves the prototype for practical purposes, simplifies the circuit structure, and improves the stability of phase measurement of the SIP instruments. The tests in mining areas show that the improved SIP instrument has lower cost, stronger anti-interference ability, higher practicability, and is suitable for large-scale promotion and application.