The research on the soil’s geochemical background value and reference value is an important basic work in the field of geosciences. The publication of Soil Geochemical Parameters of China is an important result achieved on the basis of the China’s nation-wide multi-target regional geochemical survey and the high quality and precision big data studies. This paper outlines some basic requirements including the geochemical investigation method and the sample testing quality, and explains the acquisition means and accuracy level of the big data. We mainly discuss on a macro-scale the variation features of Chinese soil’s background value versus reference value, including:① to study the ratio feature between Chinese soil’s geochemical background value and the continental crust abundance of the world, and explain the overall characteristics and basic rules of Chinese soil element(oxide)background value versus the global continental crust abundance;② through comparing the soil element(oxide)background values of Liaohe river, yellow river, Yangzi river and Zujiang river catchment areas with the continental crust abundance, to study the variation features of soil element(oxide)background values of each large river catchment area from north China to south China versus the global continental crust abundance;③ through comparing the soil background value of the above mentioned large river catchment areas with Chinese nationwide soil background value, to study the soil background value’s variation features of each large river catchment area relative to Chinese nationwide overall soil background value;④ taking the soil background value of the “first environment”, which represents the natural background with almost no human influence, as the baseline, to study soil’s geochemical enrichment characteristicsof the “second environment” which is deeply influenced by human activities;⑤ through comparing the ratio features of “first environment” soil geochemical background versus “second environment” soil geochemical background of each large river catchment area and region in China, to study enrichment and depletion rules of the element index under different natural environment and geographic landscape of the whole China. The study of Soil Geochemical Parameters of China is on the basis of geochemical big data. With huge amount of information and very rich connotation, this study represents China’s high quality and accuracy, and is an unprecedented academic achievement and milestone in China’s geochemical research history. This study will provide basic information for many scientific fields including the pedology, ecology, environment science and biology; provide important basis for the research of major scientific subjects such as global change, global environment and global governance; and provide evaluation criteria for the scientific management and decision-making of China’s natural resources, ecological & environmental protection, agricultural & rural development and health sectors. Only by exploring some problems on a macro-scale in this paper, we have found many ecological information, natural rules and scientific questions which need us to make in-depth research and application practice. It is predictable that along with the in-depth research and extensive application of Chinese soil’s geochemical parameters, the geochemical research will be further involved into China’s economic and social development, make positive contributions to our country, and geochemical problems will be more concerned by China’s economic and social development sectors.The result of this investigation and research project is a concentration of many geo-scientists’ hard work and wisdom, shows us these geoscientists’ rigorous scientific spirit and respectable dedication and responsibility, demonstrates China’s high quality and accuracy, and represents the high quality geo-scientific advancement of China.

Based on the data of the multi-purpose regional geochemical survey in the Songliao Plain, Northeast China,the authors calculated the soil organic carbon density and reservesin surface soil(0~20 cm) and compared them with the soil organic carbon density obtained during the second national soil survey. Then it analyzed the main influencing factors of the distribution and changes of the soil organic carbon density in the plain. The results are as follows. The surface soil of different soil types in the Songliao Plain significantly differ in the proportion of organic and inorganic carbon. Specifically, the organic carbon in swamp soil, dark brown soil, peat soil, albic soil, paddy soil, and black soil accounts for 90% of the total carbon in soils, while that in chestnut soil, fluvo-aquic soil, aeolian sandy soil, and cinnamon soil accounts for less than 80% of the total carbon content. The organic carbon reserves in the surface soil in the study area is about 1,448 Tg at present. It has suffered a loss of about 115.94 Tg since the 1980s, decreasing by 7.4%. About 104.88 Tg (90.5%) of the lost carbon reserves has entered into the atmosphere. In terms of different land use types,the carbon reserves in arid land decreased by 76.12 Tg, which contributed the most CO₂ to the atmosphere, followed by the carbon reservesin saline land and grassland, which decreased by 16.32 Tg and 15.93 Tg, respectively. It is considered in this study that the main reason for the decrease in soil carbon pool is the temperature rise in the Songliao Plain in the past 30 years. In detail, the reduction in soil organic carbon pool in arid land and grassland induced by the temperature rise accounted for 70% of the total loss of soil organic carbon pool, while the reduction in organic carbon caused by other factors such as agricultural production, change in land use, and soil erosion accounted for only about 30% of the total organic carbon loss.

High quality and high yield of famous agricultural products are often related to the specific eco-geological environment and geochemical conditions of the producing area.This paper develops the eco-geological and geochemical adaptibility model of Myricarubra in Longhai City. Geological and geochemical survey for famous producing area of Fugong bayberry were conducted.Theresults show that the geological background of the high-quality bayberry producing area in Longhai is granitoid, and the values of Mn, P, S, Zn, Al₂O₃, Na₂O, K₂O and available Mn, P, S in soil are relatively high, whilethe values of heavy metal elements such as As, Cd, Cr and Hg are low. The terrain of this area is hilly and mountainous with low elevation and low slope, and soil types are mainly red and yellow soil.According to the eco-geological model and on the basis of the data of 1∶50,000 soilquality geochemical survey, 1∶50,000 geological map as well as topographic, geomorphic and soil type maps of Longhai City, the suitable planting area of Myricarubra in Longhai was delineated, which involve 259.89 km² optimum planting area and 70.62 km² suitable planting area,which is about 5 times the existing planting area. These results could give geological and geochemical basis for planting planningof Myricarubra in Longhai City.

This study investigated the elements of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in greenbelt soil in five types of functional zones in the urban area of Tianjin City, namely residential and educational zones, traffic greenbelts, industrial zones, parks, and river banks. The results are as follows. The overall accumulationof heavy metals in the greenbelt soil is in the order Hg>Cd>Pb>Zn>Cu, with the average content of As, Cr, and niapproximating to the background values. Pb, Zn, Cu, and as have the highest content in the greenbelt soil in industrial zones, while Cd, Hg, Ni, and Cr have the highest content in river banks. Heavy metals mainly migrate intogreenbelt soil by means of atmospheric deposition.Moreover, the accumulation coefficient of heavy metals in greenbelt soil is significantly correlated with the ratio of the average content of heavy metals in atmospheric deposition and the background value of the heavy metals in the soil. Meanwhile, the difference in heavy metal content between the greenbelt soil in different functional zones are mainly caused bythe difference in the quantity of the heavy metals in the atmospheric deposition. Besides, the greenbelt soil on river banks is also affected by sewage irrigation and river sediments, and industrial and household waste may also cause local accumulation of heavy metals.

Based on 238 rock samples and 4,931 soil samples collected from the Jiucheng-Jiemao area of Yingjiang County, Yunnan Province, and compared with other geological units, this paper is focused on the study of geochemical characteristics and sources of heavy metals in granitic magmatic rocks and soils as well as ecological risk assessment of soil heavy metals. According to the results obtained, the granitic magmatic rocks and Gaoligongshan group(Pt₁GL.)rocks have similar provenances or inheritances. The Pb content in the two kinds of rocks is higher than that in the upper crust, while the content of other heavy metals is lower. The soil heavy metal content and change characteristics of the Quaternary (Q^a), Mangbang formation (N₂m) and Gaoligongshan group (Pt₁GL.) are basically the same as those of the granitic magmatic rock, which are significantly lower than the Quaternary (Q^b) and Guanshang formation (D₁g). Combined with lithologic compositions, the soil parent materials of the Quaternary (Q^a), Mangbang formation (N₂m) and Gaoligongshan group (Pt₁GL.)may be mainly granitic magmatic rocks. The soil heavy metal values of the granitic magmatic rock and Guanshang formation (D₁g) are mainly affected by natural sources, and the influence of human activities is little. The geoaccumulation index and the potential ecological risk index indicate that the granitic magmatic soil has a low ecological risk of heavy metals and is a clean soil.The soil-forming parent materials of farmland with the production function of grain, sugar, vegetable, etc. in Dehong Prefecture are mainly granitic magmatic rock, but related study work is insufficient. Through comparative research, it is believed that Dehong Prefecture has great potential in developing green and pollution-free food production.

To study the quality of the arable soil in peri-urban area of Huangshi City, the present research focused on analyzing heavy metals distribution characteristics, assessed its risk to environment, and subsequently identified its sources by multivariate statistical analysis based on high-density topsoil and subsoil sampling. The results show that the content of heavy metals in the soil isas follows: As (5.2×10^-6~155.9×10^-6), Pb (19.2×10^-6~426.1×10^-6), Hg (0.012×10^-6~1.823×10^-6), Cd (0.03×10^-6~4.59×10^-6), Zn (34.8×10^-6~529.6×10^-6), Ni (8.5×10^-6~86.2×10^-6), Cu (16.52×10^-6~104.39×10^-6) and Cr (51.2×10^-6~145.5×10^-6). The average content of Cd exceeds the regional soil environmental background value, and Cd even exceeds the soil risk screening value of agricultural land. Heavy metal pollutants are mainly concentrated in the topsoil above 40 cm. Among the land use types, paddy lands and dry lands are heavily polluted, and Cd, As and Pb are the main pollutants. In paddy lands, As, Pb, Cu and Zn exhibit slight pollution, Cd and Hg exhibit moderate pollution, whereas Cr and Ni do not exhibit pollution. In dry lands and forest lands, As, Pb and Hg exhibit slight pollution, Cd exhibits moderate pollution and Cr, Cu, Ni and Zn do not exhibit pollution. The multivariate statistical analysis indicates that Cr and Ni in the soil of the study area are of natural origin and related to the parent material of the soil. Cd, Pb, As and Hg are mainly of anthropogenic pollutants, which is related to high-intensity industrial and mining production and sulfide mineral acidification release in Huangshi City.However Cu and Zn constitute mixed sources, partly from soil environmental background, and partly from human activities and industrial production emissions.

The formation of natural selenium-rich soiltends to be controlled by the parent materials. Spatially, it is closely related to the distribution areas of selenium-rich rocks such as black rock series, coal-bearing rock series, carbonaceous mudstones (shales), argillaceous limestones, and volcanic rocks. Selenium-rich soil of different genetic types greatly differs in development suitability. However,agenetic classification scheme of natural selenium-rich soil is yet to be developed. This paper sorted out the genesis of natural selenium-rich soil and divided it into three categories and 10 subclasses according to the major controlling factor of selenium source in soil (parent materials) based on existing classification schemes. Then it briefly reviewed the primary characteristics and development suitability of selenium-rich soils of four major subclasses, i.e., black rock series, coal-bearing rock series, volcanic rocks, and epimetamorphic rocks.Based on this, this study proposed assessment indices of the development suitability of natural selenium-rich soil.

This study aims to determine the reference areas for the arrangement of background points in soil environment monitoring in Henan Province. Firstly,based on the data of 1∶200,000 regional geochemical stream sediment surveys and 1∶250,000 land quality geochemical surveys of Henan Province as well as the map of soil parent materials of Henan Province, outliers were eliminated using iteration and a statistical method according to the definition of geochemical background. Then the background interval values of five heavy metals (i.e.,Cd, As, Pb, Hg, and Cr) in parent materials of different types were calculated according to the ±2 deviationof the mean. Finally, data points were extracted according to the background interval values of each element and then the grid of the data points was extracted using the software ArcGIS. In this way, the reference areasfor the background points layout in Henan Province were formed. This study will provide technical bases for the optimization of background points in the soil environment monitoring in Henan Province.

Based on 2D and 3D seismic data, this study analyzes the geometric characteristics,horizontal shortening,and active time of the Alar fault in the southwestern Qaidam Basin in detail and explores the kinematic characteristics,formation mechanisms,and significance for hydrocarbon accumulation during the whole Cenozoic.The results are as follows.The Alar fault can be divided into the western segment in NWW trending and the eastern segment in nearly NS trending,which are nearly vertical. As shown in sections,the western segment inclines southward with a relatively small dip angle,while the eastern segment inclines westward with an almost vertical section.The Alar fault has been active since the Early Cenozoic.The activities of the western segment are dominated by thrust,with horizontal shortening and vertical uplift both exceeding 3 km and strike-slip motion for about 1 km.The activities in the eastern segment are dominated by dextral strike-slip motion,with horizontal shortening and vertical uplift of about 1 km and strike-slip motion of up to 3 km.The formation and activities of the Alar fault are jointly affected by the northward compression imposed by the Qimantage orogenic belt to the south and the Altun left-literal strike-slip fault to the west.There is a close spatial-temporal matching relationship between the fault activities and the formation of oil and gas in the southwestern Qaidam Basin.Therefore,the fault activities are of great significance for the formation of oil reservoirs.

Sandstone-type uranium deposits are the main type of uranium resources in China. Geophysical exploration methods are widely used to explore energy and mineral resources such as oil, gas, and coal in sedimentary basins, and they should also play an important role in the exploration of sandstone-type uranium deposits. Based on actual exploration conditions, this paper explores the current application status, existing problems, and development trends of geophysical exploration methods from the aspects of the metallogenic theory and ore-controlling factors of sandstone-type uranium deposits. In practical application, geophysical logging plays an important role in the direct positioning of uranium deposits and the quantitative calculation of uranium content per square meter, while the surface geophysical methods enjoy advantages in ascertaining uranium metallogenic environments such as sedimentary suites, faults, the lithology of rock masses, and basement relief. To ensure the application effects of geophysical exploration methods, it is necessary to closely combine the existing geological information in the whole process of method selection, survey line arrangement, and data processing and interpretation. Meanwhile, it is also necessary to select comprehensive geophysical exploration methods as required by actual conditions. It should be emphasized that the gravity and magnetic data can provide bases for the selection of optimal exploration areas inside basins and the arrangement of geological and geophysical exploration in the late stage. Therefore, enough attention should be paid to them in the prospecting and preliminary exploration work of uranium deposits.

The Hengyang Basin is a junction zone between the Yangtze Plate in South China and the Cathaysian Plate. It is expected to have great potential for rich mineral resources given its complex geological tectonic movement history. This paper aims to deeply analyze and explore the stratigraphic framework and deposit occurrence mechanisms on the northwestern margin of the Hengyang Basin. To this end, a series of geophysical surveys in this area were carried out. Firstly, a multi-method survey of a long section spanning the Ziyunshan and Nanyue rock masses was conducted and the structure of the northwestern margin of the Hengyang Basin was accordingly analyzed. Secondary, large-scale fine detections of subsections in the key sections/blocks were carried out using induced polarization (IP) sounding. Meanwhile, the characteristics of the IP response of the Changshou-Hengyang-Guanyin’ge fault were analyzed especially, and the genesis and metallogenic prospect of the fault were explored. Finally, the migration rules of ore-forming materials on the margin were investigated based on comprehensive information such as regional geological and gravity anomalies. The combined results confirmed that the Hengyang Basin is a typical sub-mantle plume-mantle branch system.

In recent years, Northwest Nonferrous 713 General Team Co., Ltd. has successively carried out geophysic exploration work such as IP middle stage in Chigou ore rights area, and gained Many achievements, but the information about Chigou rock mass distribution, rock and ore controlling fault structure, rock contact zone and other information is not fully clarified. Based on the newly completed gravity, magnetic and electric comprehensive geophysical prospecting data of Chigou Cu-Mo deposit, combined with the existing geological and borehole data in the study area, gravity, magnetic force and AMT data were processed, and the characteristics of gravity and magnetic anomaly field in the area were comprehensively analyzed, the rock and ore controlling fault structure was delineated and the main magma invasion channel was found. The intrusion range of concealed rock mass closely related to mineralization was determined, and two concealed and semi-concealed rock masses were delineated. The geophysical field characteristics of concealed rock mass, contact zone of rock mass and mineralized body are clarified, and the contact zone of rock mass and stratum is the main metallogenic site. The favorable prospecting area is predicted, and the prospecting breakthrough is obtained through drilling verification. The research results have important reference significance for further exploration of copper and molybdenum deposits in this area.

Based on investigations of geological characteristics of ground surface and deep parts and three-dimensional geological modeling, this study preliminarily ascertains the lithology of rock masses and the spatial distribution characteristics of faults in the Suanjingzi area, obtaining and the following understanding. In terms of lithology, the Suanjingzi area mainly consists of granodiorites with an exposed area of about 176 km² and a depth of more than 2 km. The granites occur in the form of batholith and are generally distributed in the NE-SW trending, which is consistent with the direction of the main tectonic line in the study area. Meanwhile, they feature single lithology, high integrity of deep rock masses, and slight rock alteration. There are nine faults in the study area in total. They have roughly developed in rock masses and have steep dip angles. A rock mass with an area of greater than 31 km² can be selected from the granites, which has single lithology, large enough volume, and high integrity and maybe used as a candidate site of the disposal repository of high-level radioactive wastes in the future. Overall, the Suanjingzi area has suitable geological conditions as a pre-selected site for the geological disposal of high-level radioactive wastes.

Huashan rock mass, Laoniushan complex and Huayangchuan ductile shear zone play an important role in the process of mineralization in Huayangchuan area of North Qinling Mountains. They are not only a record of tectonic evolution, but also an important indicator of tectono-magmatic mineralization.In this paper, based on the systematic study of the surface and airborne gravity, magnetic survey data, and surface electrical section and other geophysical data in Huayangchuan area, statistical analysis of physical properties;merge aviation data and ground data; and proceed 2.5 dimensional interactive inversion and three dimensional inversion with prior information constraints. The regional three-dimensional geology-geophysics model of Huayangchuan area is constructed, which provides the geophysical basis for the study of regional geological background and deep geological structure. Inference and interpretation of Huashan rock mass, Laoniushan complex and Huayangchuan ductile shear zone of the three dimensional shape and spatial distribution. This paper has analyzed and discussed the deep contact relationship among huayangchuan ductile shear zone, Laoniushan rock mass and Huashan rock mass, which has certain guiding significance for deep prospecting of uranium, molybdenum and other deposits in the peripheral contact zone of the large rock mass.

Over the past nearly 30 years,geophysical technical standards for geological surveys have successively experienced zero standards,sparse standards,and standard series.As a result,a series of standard systems of gravity,magnetic,electrical,seismic,and radioactive prospecting have been gradually established,which play an important role in establishing standardized work procedures and promoting new methods and techniques in the field of geophysical techniques for geological surveys in China.However,with the transformation and development of geological surveys in China,the current standard systems of geophysical prospecting are yet to meet the requirements of geological surveys at present.The paper summarizes the development status of geophysical standards for geological surveys in China and explores the research direction and development trend of the standardization of geophysical techniques according to the need for geophysical methods and technologies in the transformation and development of geological surveys in China.

The huge Cenozoic sediments have a strong absorption and attenuation effect on electromagnetic waves and seismic waves, and it is difficult for a single method to achieve the purpose of coal exploration. In the coal exploration of a huge Cenozoic coverage area at the western foot of the Xiangshan Mountain in Ningxia, the investment in 2D seismic exploration failed to achieve the expected purpose. In this study, the electrical method with controlled source audio magnetotelluric method as the main and direct current sounding as the supplementary method was implemented for exploration. The comprehensive method successfully delineated the range of coal-bearing strata and determined the coal-bearing nature of the coal-bearing strata. Through drilling verification and subsequent geological survey work, the comprehensive method of electro-seismic was proved to be economical and effective in coal prospecting in the area covered with huge Cenozoic sediments.

Tight sandstone reservoirs have the characteristics of strong heterogeneity,poor physical properties,and difficulty in exploration and development.In order to find the high-brittleness section of tight sandstone reservoirs in the Weibei oilfield and fracture this kind of reservoirs,this paper proposes a method based on ANN (artificial neural network) model for shear wave prediction under the condition of lacking suitable brittleness prediction methods for tight sandstone reservoirs in the Weibei oilfield at present.The predicted value is highly consistent with the measured value,and the brittleness index of each well in the study area is calculated by the elastic parameter method further.For the purpose of improving the accuracy of the brittleness index predicted by this method,X-ray diffraction full-rock analysis of fewer wells in the study area is utilized,and it is concluded that quartz and carbonate rocks are the main brittle minerals of the Yanchang formation in the study area."(quartz+carbonate) content/ total minerals " are adopted to calculate the rock brittleness index and then improve the brittleness index predicted by the elastic parameter method.This technique which takes advantage of the balance between the mineral composition method and the elastic parameter method not only improves the prediction accuracy but also makes up for the lack of array acoustic logging and whole rock analysis data.This method was used to predict the brittleness of tight sandstone reservoirs in the WB2 well area of the Yanchang formation in the Weibei oilfield, and high-brittleness sections of WB52 and WB49 were further chosen to be fractured.It is shown that the production stimulation effect was obvious after fracturing,which is of great significance for guiding hydraulic fracturing.The method and process proposed in this paper have strong application and promotion value.

By the modification of the AS350-B3 helicopter, the airborne gravity and magnetic measurement system suitable for the medium-low mountainous area is integrated. The 3D measurement network with the maximum slope of 3° was designed, and the gravity and magnetic measurement method by helicopter was first applied in the medium-low mountainous area. The measurement results show that the slow rise and fall measurement method can keep the aircraft track well in the three-dimensional space, and can effectively control the height difference between the intersection points of the survey line and the cross line, so that the survey line and the cut line form a network, which plays a beneficial role in the magnetic field leveling. The comparison of the results of the horizontal flight measurement and the slow rise and fall measurement shows that the slow rise and fall measurement method can not only take into account both gravity and magnetic measurement methods, but also exert more obvious mapping effect than the horizontal flight anomaly characteristics.

To meet the accuracy requirements of airborne gravity surveys for deep resource exploration, an airborne gravity survey platform has been developed and integrated based on previous research. The platform system is an airborne gravimeter platform consisting of a three-axis stabilized platform and a quartz flexible pendulum accelerometer. It adopts self-calibration technology and the real-time error estimation and correction technology of platform attitude. Meanwhile, it is equipped with a navigation and positioning system, a vibration reduction system, an unattended system, and data processing software. Flying survey data show that the internal coincidence accuracy of the repeated-line flight data of the airborne gravity survey platform is less than 0.6×10^-5 m/s²(100 s), reaching the international advanced level. Therefore, this platform allows the technology and equipment of airborne gravity surveys to be localized.

The shallow 3D seismic reflection exploration has a large amount of data,accurate migration, and high lateral resolution.It can overcome some difficulties of the 2D seismic exploration in the city caused by the obstacles,such as obliquely intersection of the survey line with the structural strike,poor shallow structure detecting,and inaccurate fault locating.Therefore,shallow 3D seismic exploration can provide higher-quality data for urban underground space exploration,active fault detection,and geological disaster prospecting.However,urban 3D seismic exploration faces some challenges of shallow imaging,such as inhomogeneity of surface velocity,strong environmental noise,and uneven distribution of shot points caused by obstacles.To improve shallow imaging,tomographic static correction,pre-stack multi-method combination denoising,regularized interpolation of pre-stack data,and combined normal moveout strength cutting.The result shows our processing can improve the quality of shallow imaging of 3D seismic data.

The geological conditions of Zhangjihuai railway is complex,the structure and karst are extensively developed,and hence the risk of construction is high.Based on the construction of Zhangjihuai railway,this paper expounds the difficulties,prediction principles and key geophysical techniques of the railway tunnel geological prediction,and summarizes a set of technologies for the railway tunnel geological prediction.The practical examples show that the five-step method is useful in geological prediction,the surface exploration data are important for dividing the key sections for macroscopic control,the long-distance prediction and short-distance prediction of geophysical exploration technology should be used together,and the advance drilling must be used to verify the geophysical exploration anomalies,so that the prediction work can be a closed-loop, which is conducive to avoiding risks and reducing false reports.The whole set of advanced forecast technologies of Zhangjihuai railway is feasible and useful,which is worthy of spreading.

Yidong fault zone is rich in oil and gas,and the exploration space of the tertiary lithology body is large,but the exploration degree is low.The main reason restricting the exploration efficiency is that the reservoir heterogeneity is strong and the distribution rule is complex.At the same time,due to the limitation of seismic data and conventional seismic prediction technology,the favorable reservoir seismic prediction of lithologic body is difficult.Based on the high density three-dimensional azimuth seismic data of YD area,the authors carried out the research on the favorable reservoir seismic prediction of the fourth member of Shahejie Formation.Firstly,the difference of azimuth seismic properties was used to predict the distribution of fractures in the reservoir.Then the anisotropic reservoir prediction technique based on anisotropic parameter inversion was used to describe the anisotropic characteristics of the reservoir.Finally,combined with the results of two kinds of seismic prediction techniques,with the fracture distribution as the main predicted object and the reservoir anisotropy characteristic as the restricted condition,the authors described the fracture development degree of the limestone reservoir in the fourth member of Shahejie Formation comprehensively and improved the prediction accuracy of the favorable limestone reservoir in the fourth member of Shahejie Formation.

The down-hole method under surface horizontal forward and reverse hammer excitation is frequently used for on-site tests of shear wave velocity.Based on the dynamic finite element method,this paper establishes a three-dimensional analysis model of the down-hole method used for shear wave velocity tests under the surface horizontal forward and reverse hammer excitation.Meanwhile,it determines the solutions of the wave response of linear elastic half space under the surface horizontal hammer excitation through explicit stepwise integration of time-domain lumped mass dynamic finite element.Furthermore,it analyzes the waveform characteristics of points at different depths and the rationality of the theoretical basis of shear wave (S-wave) velocity tests under the surface horizontal forward and reverse hammer excitation.As indicated by the results,the theoretical basis of S-wave velocity tests (i.e.,the non-inversion of P-wave onset but inversion of S-wave onset) using the down-hole method under surface horizontal forward and reverse hammer excitation is not tenable.In addition,the numerical simulation results have been further verified reasonable by the analytical solution of the wave motion in the linear elastic half space under the surface horizontal forward and reverse excitation.

The YS1 area in Sichuan basin has undergone multiple stages of tectonic evolution.The faults are characterized by multiple stages and multiple strikes,and serious mud losses occurred in the drilled well.It is difficult to finely characterize fracture and analyze structural development when the conventional seismic interpretation method is used.In this study,according to the actual situation,ant tracking technology was used to predict fractures,whose accuracy was improved by noise reduction,continuity enhancement,fault boundaries height,and fake structures elimination.The process is as follows:firstly,the input seismic data volume is pre-processed by structure-oriented filtering and discontinuity detection,then the ant tracking parameter settings are optimized,and finally the ant tracking under the occurrence control is performed.The data can not only be used to assist fault interpretation but also provide a data basis for subsequent fault development analysis and horizontal well location deployment.

Transmission seismic exploration in the coal mining face is one of the important geophysical surveys to figure out the geological hazards of coal seam.The rationality of identifying the airy phase from the transmitted channel waves is closely related to the accuracy of the tomography.Nowadays,S-transform is widely used in the analysis of dispersion curve,however,its application is limited with the fixed window.In order to improve the identification accuracy of the airy phase of the dispersion curve,this paper introduces the generalized S-transform with adjustable window into the analysis of dispersion curve.The window of generalized S-transform is analyzed by temporal full width at half maximum (temporal FWHM).For a frequency range,a wider window indicates a lower temporal resolution and a higher frequency resolution,and a narrower window indicates a higher temporal resolution and a lower frequency resolution.The time-frequency resolution can be adjusted quantitatively according to the relationship between the temporal FWHM and the parameters of generalized S-transform in application.The synthetic and real data result show that the generalized S-transform can effectively improve the time-frequency resolution and the airy phase characteristics of the dispersion curve.It is helpful for the interpreter to pick up the airy phase of the transmitted channel waves accurately.

Channel sand bodies have the characteristics of thin single-layer thickness,small scale,scattered distribution,and strong heterogeneity.In conventional model inversion and prediction,there are problems such as serious modeling,low lateral resolution,and easily damaging the structural morphology of sedimentary bodies,which results in low prediction accuracy.This study uses the frequency-divided configuration inversion method to accurately predict channel sand.This method fully considers the dominant frequency band of logging and seismic and waveform change characteristics,and combines the low,medium and high frequency band models to form the initial model.Then under the framework of Bayesian,the inversion result of the whole frequency band is corrected through the constraints of the seismic synthesis record.In the practice of forecasting thin and small channel sand reservoirs in the Zhaohuangzhuang area,the inversion results have higher vertical and horizontal resolutions,which better support the well placement in this area.The sand body is reasonable and clear for the horizontal stacking relationship and sharp point,and conforms to the distribution characteristics of the sediment body of the meandering river for the plane distribution.Meanwhile,the predicted rate of resolving reservoirs with a thickness of more than 4 m is over 80%.The precise prediction method of thin and small sand bodies based on frequency division configuration inversion has certain guiding significance for the prediction of seismic reservoirs in similar regions or zones.

A 1D inversion code is developed for the loop-source transient electromagnetic method (TEM) based on the open-source code Dipole1D and Occam's algorithm. This code is tested by a four-layer stratified model. Then, the model with a tilted earth-air interface is considered, for which the synthetic data are calculated by 3D finite-element method. The inversion results show that 1D inversion can be directly used for the scenario with tilted interface. Finally, this 1D inversion code is used for a field case, in which TEM is employed to delineate the 3D distributed domains of a basalt which intruded into shale and sandstone. The inversion result shows that the thickness of the basalt coincides with the drilling data, and the shape of the basalt like a pot bottom.

Tippers are important parameters for the interpretation of airborne magnetotelluric data, and the study on the response characteristics of tippers is of great significance for the data interpretation. This study firstly introduces the basic principle of airborne magnetotelluric and ZTEM airborne magnetotelluric data acquisition system, then simulates the tipper response of the simple abnormal bodies using the three-dimensional finite element method, and finally analyzes the response characteristics of tippers T_x and T_y when the survey lines obliquely intersect with a lithologic interface. As indicated by the results, both T_x and T_y responded to the lithological interface in the case that the survey lines obliquely intersected with a lithologic interface. Meanwhile, the tipper exhibited corresponding laws with the change in the direction of the survey lines in that case. This study further deepens the understanding of the response of tipper to lithologic interfaces and will provide references and guidance for the interpretation of tipper data.

The regularization term for semi-airborne transient electromagnetic regularization of long-line source usually adopts L2 norm, and the fitting result is relatively smooth, which cannot effectively describe the layer interface information. Aiming at the stratified medium steep change model to realize the inversion algorithm whose regular term is the L1 norm, the authors transform the original problem into the L2 regularization sub-problem by the iterative re-weighted least squares method to solve the problem of non-differentiation in the L1 norm; OpenMP technology is used to solve the problem. The parallel calculation of the Jacobian matrix improves the inversion speed; the adjustment strategy of the adaptive regularization factor segmentation iteration method is analyzed and improved. The improved adaptive regularization factor adjustment strategy is more suitable for semi-airborne transient electromagnetic inversion algorithm of L1-norm regularization. Finally, the resistivity is inverted and compared with the Occam inversion results. The results show that the inversion of L1-norm regularization can highlight the electrical interface conforming to the real model after sufficient iterations, and the inversion resistivity is closer to the true value of the model.

In this paper, high density electrical resistivity method was employed to study the salt-water intrusion transition zone combined with water quality survey sampling. Through an analysis of typical high density measurement section, 10 Ω·m is preliminary determined as the apparent resistivity indicator of the brackish water boundary in this area, and the location of brackish water zone, brackish water transition zone and fresh water zone in brackish and fresh water transition zone is preliminarily deduced. The result shows that the high density electrical resistivity method has the advantages of high efficiency, time saving and low cost, and can be used as an effective means to monitor the large range of salt water intrusion together with other methods.

The prospecting of shallowly concealed karst caves is studied using the cross-hole ultra-high density resistivity method. The results are as follows. It was feasible to prospect Karst caves using existing survey boreholes according to the cross-hole ultra-high density resistivity method. The transverse and longitudinal distribution ranges of karst caves can be directed reflected by the distribution characteristics of the cross-hole resistivity obtained through forward and inverse calculations. Meanwhile, it was difficult to distinguish the connectivity between karst caves, and the depth deviation was the distance between two adjacent electrodes. It is suggested that the depth of the boreholes used should be consistent, the ratio of the borehole depth to the borehole space should be higher than 1.5, and the electrode space should be 1~2 m in practice.

To detect the water-rich areas in coal seams, the wide-field electromagnetic method (WFEM) was employed in the Xinyuan mining area of Huayang New Material Technology Group Co., Ltd. for the first time. Meanwhile, the controlled source audio-frequency magnetotellurics (CSAMT) was used for comparison. According to the comparison results of the apparent resistivity curves, frequency-apparent resistivity pseudo sections, and inversion results, WFEM enjoys the advantages of large detection depth, high efficiency, and high precision and thus serves as a new effective technology for the detection of water-rich areas in coal mines.