In oil and gas exploration,multiples are usually regarded as the coherent noise that affects the processing and interpretation accuracy of seismic data.Therefore,the study of multiple suppression methods has always been an important research direction in the field of geophysical prospecting.Given that the surface-related multiples are the most developed multiples in seismic exploration,especially in marine seismic exploration,it is necessary to conduct a deep study on the suppression methods of surface-related multiples.At present,the surface-related multiple suppression method that enjoys high accuracy and is widely applied at home and abroad is the feedback iteration method based on the wave equation.This method takes the original seismic data as the predictive factor and requires no other prior conditions and allows for high-precision suppression of surface-related multiples driven by data.A series of more advanced methods have been developed based on the theory of this method in recent years.This paper briefly introduces the theoretical basis of the feedback iteration method(i.e.,the feedback iteration model) firstly and then describes the surface-related multiple suppression mechanisms of the four methods developed based on the feedback iterative model, namely SRME,the inverse data domain method,EPSI,and Cl-SRME.Finally,it compares the advantages and disadvantages of these four methods and proposes the research prospects of multiple suppression methods based on the feedback iteration model.

This paper summarizes the current status and progress of major system integration technologies for airborne geophysical prospecting used abroad from 2015 to 2020. During this period, some old systems were improved, while some became obsolete. Meanwhile, new system integration methods constantly emerged during this period. Specifically, towed birds using geomagnetic gradient began to be widely applied. At the same time, with the significant improvement of flight control and load capacity, UAVs were widely applied in magnetic, electromagnetic, gravity, and gamma-ray spectrometry fields. SQUID magnetic tensor gradiometers and FTG gravity tensor gradiometers were successively put into commercial airborne geophysical prospecting. The signal-to-noise ratio of electromagnetic systems was significantly improved, and CsI (Tl) scintillators were preferred by companies producing gamma-ray spectrometry instruments.

The Yubei area in Tarim Basin is characterized by complex geological conditions and desert land form with widely distributed mobile sand dunes. Seismic signals are severely attenuated in the area due to the absorption by desert surface, leading to a low signal-noise ratio and low resolution of data and thereby making hydrocarbon exploration difficult. The method using mobile forms for geochemical prospecting of hydrocarbons is not affected by the desert land form and can detect information of underlying hydrocarbons in adirect, rapid, and economic manner. The mobile form indicators of free hydrocarbon gas, headspace gas, fluorescence spectra, and microorganisms were selected for the geochemical prospecting of hydrocarbons in the Yubei area, Tarim Basin. The results are as follows. The anomaly zones of the methane,butane oxidizing bacteria and the integrated indicators (entropy) can effectively indicate the hydrocarbon-bearing scope of the area controlled by Well Yubei-1. Based on the spatial combination and configuration relationship of the anomaly zones of these indicators, six favorable zones of geochemical anomalieswere delineated, and their integrated anomalous levels were determined. Among these favorable zones, the tectonoclastic zone of Well Yebue-1 is the most favorable target area for hydrocarbon exploration, followed by the marginal regions of the tectonoclastic zone. These results provide a geochemical basis for further deployment of hydrocarbon exploration in the Yuebei area, Tarim Basin.

Regarding the genesis of the geothermal resources in Guizhou Province, most researchers tend to think that the geothermal resources were formed from the temperature rise induced by the mechanical energy of the “geothermal gradient” controlled by seismic activities and faults and that the geothermal resources do not possess from magma heat sources nor have the conditions of radioactive heat generation. Based on the research on the previous achievements, the characteristics of geothermal reservoirs and cap rocks, and regional gravity and magnetic data, the inference of the deep faults and intermediate-acid and basic-ultrabasic rock masses, and the analysis of regional distribution characteristics of natural geothermal resources and geothermal wells, this study proposes two possible basic genetic models of the geothermal resources in Guizhou. One is that automatic temperature rise and cyclic heat generation caused by the “geothermal gradient” controlled by deep faults. The groundwater with continuous temperature rise driven by this model is the most developed. The other genesis is the waste heat of magmatic rocks. It is inferred as a new type of heat generation and genesis supplement. As an important regional metallogenic region of uranium and thorium in China, Guizhou Province has only been researched at a low level and on a small scale, with a small amount of available data. Therefore, it is not clear whether there are basic conditions of radioactive heat generation in Guizhou Province. The in-depth study on the genesis of geothermal resources can provide relevant bases for the accurate surveys of geothermal resources and the expansion of prospecting direction in Guizhou Province in the future.

The understanding of the Paleogene Dongying formation and the Jixianian Wumishan formation have been gradually deepened with the exploration and development of deep thermal reservoirs in the Binhai New Area.This paper analyzes the hydrochemical characteristics, reservoir temperature, and hydrogeochemical effects of the geothermal fluid of the Dongying and Wumishan formations, thus providing bases for the further development and utilization of deep geothermal resources. The Wumishan formation in the Ninghe salient is adequately recharged. In contrast,the Dongying formation occursin a relatively closed environment, and the geothermal fluid in it is at a state of chemical equilibrium. The average temperature of the geothermal reservoirs in the Wumishan and Dongying formation scalculated using geothermometers is about 126 ℃ and 100 ℃, respectively. The geothermal fluid in both formations originates from atmospheric precipitation. Compared to the Wumishan formation, the geothermal fluidin the Dongying formation exchanges heat with rocks for a longer time and has a weaker cycling capacity. The runoff direction of the geothermal fluid in the formations is from northeast to southwest, with leaching, cation exchange, precipitation,and mixing mainly occurring during the fluid runoff.

To further verify the feasibility of the hydrocarbon-mercury superimposed halo method in the coverage area of red beds in prospecting deep deposits, this study carried out area tests of hydrocarbon-mercury superimposed halo in 4.3 km² of coverage area of Cretaceous red beds in the Hongyanxi ore block using a grid density of 160 m × 20 m. The following conclusions were drawn by summarizing the characteristics of the anomalies of metallogenic elements and hydrocarbon-mercury components in the soil in the red beds, including their superposition characteristics, field structures, patterns, spatial correspondence, and planar distribution patterns. ① There are deep-source and syngenetic superimposed fields in the soil geochemical field of red beds in the Hongyanxi ore block; ② Along the strikes of ore veins, syngeneic superimposed anomalies correspond to barren sections, while the deep-source superimposed anomalies correspond to ore sections. Along the dip directions of ore veins, the ore bodies under the control of paired bimodal anomaly mode occur in ore sections, while other ore bodies occur in barren sections; ③ Planarly, the distribution direction of zonal anomalies consisting of anomalies in the head and tail parts of the paired bimodal anomaly pattern is the pitch directions of orebodies. The superposition of different zonal anomalies indicates the occurrence of parallel blind veins in deep parts. These conclusions were verified in deep engineering, indicating ideal prediction results.

Wafangdian region is an important diamond ore concentration area in Liaoning privence of china, and the metallogenic mother rock is mainly kimberlite. Based on the 1∶10 000 high-precision aeromagnetic data in Wafangdian region, combined with the regional geological background and rock magnetic characteristics, this paper analyzes and summarizes the aeromagnetic anomaly characteristics of the kimberlite. It is found that the distribution direction and shape of the kimberlite rock are mainly controlled by the NEE and NE faults. Generally, the magnetism of kimberlite is strong, which is quite different from that of surrounding rock. The kimberlite corresponds to the NEE-trending isolated aeromagnetic anomaly, and the shape is mostly elliptical. The anomaly amplitude is not greater than 50 nT, and the anomaly distribution range is greater than the exposed area of rock mass. Aeromagnetic anomalies have important indicative significance for the prospecting of kimberlite, which can be used to guide the next geological prospecting deployment.

Concealed faults are developed in the Beijing area. They intersect with NW- and NE-trending faults, forming a potential tectonic background of earthquakes in the future. To study the relationship between active faults and the radon concentration in soil, this study measured the radon concentration of two profiles (NW- and NE-trending) in plain areas of Beijing. Through tests and analysis, this study roughly ascertained the relationship between concealed structures and the radon concentration in soil, as well as the geological factors influencing the radon concentration of soil. The results show that the radon concentration in areas with active faults is significantly higher than that in the surrounding areas, and the radon concentration in areas with complex structure and highly active faults changes more noticeably. The depth of Cainozoic strata constrains the dissipation of radon to a certain extent, and there is a positive correlation between the depth of Cainozoic strata and the radon concentration in soil. The specific activity of radionuclides in parent rocks with different soil quality also affects the background value of regional radon concentration. The results of this study determined the relationship between concealed faults ahe specific activity of radionuclides in parent rocks with different soil quality also affect the background value of regional radon concentration. The results of this nd the radon concentration in soil and identified the influence of the thickness of Cainozoic strata and parent rocks with different soil quality on the radon concentration in soil, thus serving as an important reference and guidance for the surveys of concealed faults and the research on radon concentration in plain areas of Beijing in the future.

Tropical rain forest areas feature strong chemical weathering, thick weathered layers, developed vegetation, and less exposed bedrock. It is one of the essential geological survey contents of tropical rainforest areas to obtain geological and mineral information of coverage areas by effectively utilizing overburden layers. This paper summarizes the geological and mineral information detection methods employed in exploring the geological and mineral exploration technologies in the tropical rainforest area in the Nanhanzhai experimental area, Mengman town. In detail, the methods were dominated by soil geochemical survey and sampling drill and combined geological route survey. The geological boundaries obtained using these methods roughly coincide with 1∶50,000 geological maps, and three integrated anomalies with certain prospecting prospects were delineated using these methods. This study can serve as a reference for preparing the technical guide to geological mapping methods suitable for tropical rainforest areas.

The conductivity of most formations and fractured water areas is anisotropic, while the anisotropy of formations has great impacts on transient electromagnetic observations, especially on the characteristics of horizontal components. To study the three-component responses of axially anisotropic formations using the transient electromagnetic method, this study introduced a conductivity tensor to construct the governing equation to achieve the three-dimensional three-component forward modeling of the axially anisotropic conductivity using the transient electromagnetic method based on the finite-difference time-domain (FDTD) algorithm. This study verified the accuracy of the three-component forward modeling by comparing the three-dimensional three-component forward modeling results with the one-dimensional analytical results of the isotropic and anisotropic half-space models. Meanwhile, this study established the anisotropic half-space, layered, and water-bearing models and calculated loop-source three-component responses of the transient electromagnetic method. The results are as follows. The horizontal conductivity anisotropy greatly affected the three-component responses. The x-axis anisotropy had greater effects on the ∂B_y/∂t component response than those on ∂B_x/∂t component response, the y-axis anisotropy had greater effects on the ∂B_x/∂t component response than those on the ∂B_y/∂t component response, while the z-axis anisotropy had almost no effect on the three-component responses. Moreover, the three-component responses were primarily affected by conductivity anisotropy of shallow formations. The x-axis anisotropy had greater effects on the three-component responses than the y-axis anisotropy when collection points were closer to an anomaly center in the x-direction than in the y-direction, and vice versa. The results of this study provide some valuable theoretical references for the three-component processing and interpretation of the transient electromagnetic method of anisotropic formations.

With the development of the wide-field electromagnetic method, the scope of data collection has been gradually expanded. To avoid the none-far-field resistivity distortion, this paper proposes a definition method suitable for the full-field apparent resistivity of the controlled-source electromagnetic method based on the inverse function principle. With this method, the full-field apparent resistivity can be calculated using a single component or multiple components. The full-field apparent resistivity of a homogeneous half-space model and a layered model was calculated using individual components of electric and magnetic fields and their ratios. The results show that the definition method proposed in this paper can achieve the definition of frequency-domain apparent resistivity that is not limited by space and thus can better reflect the resistivity distribution of underground media.

Through systematic forward modeling and analysis of a 3D geoelectric model containing anomalous bodies, this study proposed a rapid positioning method of anomalous bodies based on the ground-borehole transient electromagnetic (TEM) method. The analysis of the forward modeling response laws of the 3D geoelectric model containing anomalous bodies shows that the zero points of the X and Y component curves and the extreme points of the Z component curve of a pure anomaly field correspond well to the depths of the anomalous bodies; the morphologies of the X and Y component curves are basically unchanged when the sizes, resistivity, and burial depths of the anomalous bodies change but change when the orientations of anomalous bodies change. On this basis, this study proposed the following method to rapidly position anomalous bodies using the ground-borehole TEM method. First, determine the depths of anomalous bodies according to the zero points of the X and Y curves. Next, determine the quadrants (within 90°) of anomalous bodies according to the morphologies of the X and Y component curves. Finally, position anomalous bodies within 45° of boreholes according to the morphologies of the X+Y or X-Y component curves. Numerical experiments show that the positioning results of models of anomalous bodies with different orientations are consistent with those of the model designed in this study. As further verified using the ground-borehole TEM measured data of a mining area in northern Shaanxi, the inference that there is a water-filled goaf to the northwest of the borehole obtained using the method proposed in this study well agrees with the actual situation.

Areas at a low exploration level have drawn increasing attention as future contributors to reserves growth.However,they are facing many geophysical challenges.Lufeng 22 subsag is such an area due to few drilled wells and insufficient geological data.In this case,it is difficult to build an accurate low-frequency inversion model using traditional logging data or stacking velocity.Moreover,affected by ghost reflections,low- and high-frequency waves in marine seismic data are suppressed.As a result,the bandwidth of seismic data is decreased,thus reducing the authenticity and accuracy of inversion results.To address these problems,this paper firstly obtained seismic data with broader bandwidth using broadband processing technology.Then,it built a low-frequency model for areas without well control using colored inversion combined with a high-precision velocity field obtained through tomographic imaging.Based on this,this paper predicted the distribution of source rocks and reservoirs using the extended elastic impedance inversion method.This technology was applied to the Lufeng 22 subsag,enabling the successful prediction of the distribution of high-quality source rocks and favorable reservoir areas.Thick layers of middle-deep lacustrine-facies source rocks as well as oil and gas have been discovered during the drilling of the first exploration well in the subsag,which started the exploration in the new area.This study indicates that this technology effectively improves the reliability of seismic inversion of middle-deep layers using broadband data and can well identify lithology utilizing low-frequency information,thus serving as an effective technology for the lithology prediction of areas at a low exploration level.

The long-streamer and large-capacity quasi-3D seismic survey technology is used to obtain 3D seismic data that cover the study area equal times under different source-detector distances.To this end,it obtains high-density acquisition of seismic data using a single source array in shooting,a single long cable for data receiving,and traditional 2D acquisition.Meanwhile,it conducts bin regulation using the 5D interpolation method according to the 3D process flow.This technology can used to effectively improve the seismic imaging effects in medium-deep parts in turbulent sea areas,thus satisfying the need for oil and gas exploration.This study primarily introduces the key methods for the acquisition and processing of seismic data.

The special topographic and geomorphic conditions in the desert exploration area of the Guaizihu sag in the Yin'e Basin produce adverse effects on the excitation and reception of seismic data.The surface of the area is covered by hugely thick loose sand,with the thickness of the sand dunes varying in the range of 50~100 m.In the process of vibroseis data acquisition in this area,"black triangle" noise is formed in the near-trace scope due to the dual effects of the mechanical characteristics of the vibroseis and the near-surface structure,resulting in a low signal-to-noise ratio of seismic records.Since the "black triangle" noise features high energy,wide frequency range,wide distribution,and great morphological difference,it is difficult to make accurate statistics of its amplitude (intensity) in a single arrangement of the common shot domain and the common receiver domain,thus resulting in too much residual noise after the suppression of the "black triangle" noise.Given this,this paper proposes a method,in which data rearrangement is firstly conducted based on the shot-offset domain and then denoising is performed.As verified by the application of actual vibroseis data of the Guaizihu area in the Yin'e Basin,this method can effectively protect the near-trace reflection signals(especially the deep weak reflection information) while effectively suppressing the "black triangle" noise and it is effective in improving the signal-to-noise ratio of seismic data.

Ocean electric field signals are widely used in the fields of geological tectonics, water target detection, physical ocean, and the analysis of ocean physical characteristics. It is of great scientific value to collect the ocean electric field signals, while the ocean electric field is measured using ocean electric field sensors. In recent years, perovskite-type composite oxides have become a research hot spot as new materials. Among these composite oxides, SmNiO₃ is the one that possesses some unique properties including metal-insulator phase transition, strong stability in seawater, and high sensitivity to low-frequency electric field signals. Therefore, it is expected to become a new type of electrode materials in ocean electric field sensors. Domestic and foreign researchers have carried out some studies on SmNiO₃, which mainly focus on the electrical properties (especially the metal-insulator phase transition and optical properties) and preparation process of SmNiO₃. This paper systematically reviews the above research contents and preliminarily explores the feasibility of applying SmNiO₃ in marine electric field sensors.

This study proposed a constrained and adaptive regularized 1D scheme for the vertical component inversion of semi-airborne transient electromagnetics. Based on the Occam inversion, the CMD adaptive regulation scheme was used to calculate the Lagrange multiplier. Meanwhile, the feasible descent direction method with natural boundary conditions and model correction was introduced to constrain the inversion process. This combined algorithm can both improve the computational efficiency of the inversion process and guarantee the stability and reliability of inversion results. The results of layered models show that this algorithm can obtain ideal inversion results with a short iteration and computation time. Owing to the shielding effect of conductive layers and the insensitivity to resistive layers of transient electromagnetics, the inversion results of the HK model can only get the average resistivity of underlying layers. The results of the HK model verify the adaptability and effectiveness of this algorithm proposed in this study for complex geoelectric structures. A satisfactory inversion result was achieved from noise-included signals through no more than ten iterations. This algorithm exhibited good stability and convergence in numerical simulation, thus verifying that it is a feasible and effective method for interpretations of multi-source semi-airborne transient electromagnetic data.

Aiming at the difficulties that some high-porosity water-bearing sandstones and oil-bearing sandstones in deep-water clastic reservoirs in West Africa have similar amplitude bright spots and show Class III AVO anomalies with remote-trace amplitude enhancement,this paper proposes to use flat spots to detect the hydrocarbons in the reservoirs.As revealed by the data on the geometric shapes,amplitude,and phase of seismic reflection,four types of flat spots are have developed in the study area,namely individual flat spots,short-axis double flat spots,short-axis composite individual flat spots,and long-axis composite individual flat spots.The target layer W is dominated by short-axis double flat spots.Based on the forward modeling with reflection coefficients and stratigraphic dip as core parameters,a quantitative discrimination template of seismic reflection of flat spots was established in this study.The flat spot distribution was determined using the flat spot strengthening technology and the common isoline trace gathering stacking technology.It was inferred from the discrimination criteria of hydrocarbon flat spots that the upper flat spot strips represent gas-oil interfaces and the lower flat spot strips represent oil-water interfaces.Based on this and the analysis of sensitive attributes in hydrocarbon detection,the area of oil- and gas-bearing zones was effectively predicted.Therefore,the application of flat spots can reduce the multiplicity of solution in the hydrocarbon detection and improve the prediction accuracy of reservoirs.

The conventional CMP floating datum processing method based on horizontal surface assumption is not suitable for the imaging of the complex tectonic area in the Southern Junggar Thrust Belt.This paper selects the floating datum of approximate true surface as the processing datum in both the time domain and the depth domain.The pre-stack time-domain preprocessing includes selecting optimal the near-surface bottom boundary,the static correction for surface consistency of approximate true surface,surface-consistent DSR NMO velocity analysis,and residual static correction,in order to maintain the consistency of the process and parameters from the time-domain preprocessing to pre-stack depth migration (PSDM).The selection of the floating datum makes the wavefield travel time closer to the actual travel path and realizes higher imaging precision and accurate geological structure.

Traditional linear inversion of gravity anomalies is liable to encounter local minima and suffer low computational efficiency. Given this, this paper proposed a deep learning-based inversion of gravity anomalies. Specifically, two-dimensional density models of various shapes were firstly established, and gravity anomalies were obtained through forward simulation using these models to form a dataset. Then, a deep neural network was trained using the dataset. Finally, gravity anomaly data were input into the deep neural network to directly yield inversion results. Experimental results show that the inversion method proposed in this study can determine the locations and shapes of underground anomalies quickly and accurately, with high generalization ability and anti-noise ability. Therefore, this method can be used for the inversion of gravity anomalies.

This study developed a piece of visualization software of the 1D data forward modeling applicable to the controlled source audio-frequency magnetotellurics (CSAMT). This software has the advantages of friendly interfaces and simple operations. In detail, MATLAB was used to develop the core algorithms, and linear filter coefficients were introduced to solve Hankel integral in the process of forward modeling. Meanwhile, the accuracy of schemes using different linear filter coefficients was compared. The operation interfaces were designed using Java, and multi-parameter setting interfaces with a high automation degree are available. Moreover, the data processing results can be intuitively provided to users using the drawing function of the software. In the calculation process, Cole-Cole model parameters were introduced, and complex resistivity was used to replace the DC resistivity without considering the polarization effect of geoelectric bodies. Furthermore, this study carried out the forward simulation of CSAMT field source on a one-dimensional layered model of induced polarization (IP) media and discussed the IP effect of one-dimensional layered media with polarization layers at different burial depths. It was found that the frequency band of CSAMT affected by the IP effect widened with a decrease in the burial depth of polarization layers. This result is crucial to understanding the electromagnetic response characteristics of the CSAMT method with IP effect and improving the convenience and efficiency of data processing.

Horizontal well drilling is increasingly being widely applied. However, sonic logging-one of the most important reservoir assessment methods-tends to be affected by the borehole conditions in the application of horizontal wells,leading to notably reduced application effects.In view of this fact,this paper conducts the forward simulation of the radial and axial size changes induced by borehole enlargement and the changes in enlargement positions using the three-dimensional finite difference method,with the focus on the effects of borehole enlargement on the waveform amplitude,arrival times,and velocities of waves in the sonic logging of horizontal wells.The results are as follows.In the case that the borehole enlargement occurred between the sonic transmitter and the nearest receiver,the changes in borehole enlargement parameters had no effect on the measured results of the compressional and shear wave velocities but led to the notable decrease in waveform amplitude.The amplitude of compressional and shear waves decreased with an increase in the thickness and length of the enlargement cylinder but was almost not affected by the distance between the sonic transmitter and the expansion section.The compressional wave arrival time increased with an increase in the thickness and length of the enlargement cylinder but slightly decreased with an increase in the distance between the sonic transmitter and the expansion section.This study clarifies the laws of the effects of borehole enlargement on the sonic logging response of horizontal wells,and it will provide guidance and assistance for further research on the methods for influencing factor correction in the sonic logging of horizontal wells.

The resonance interference induced by electrical poles is a common type of noise in middle-shallow seismic exploration,especially for shallow data.However,relevant studies are scarce since it is rarely involved in petroleum and coalfield exploration.The Curvelet transform allows for a sparse representation of smooth regions and edges in images and can meet the requirements of time-varying signal processing,thus achieving good effects in the processing of seismic data.Based on the characteristics of the electrical pole-induced resonance interference in seismic data,this paper proposes a new method that utilizes the Curvelet transform to remove the resonance interference in original data and the steps are as follows.First,analyze the differences between the characteristics of the resonance interference induced by electrical poles and effective information in the Curvelet domain.Based on this,conduct wavefield separation according to the multi-scale and multi-direction characteristics of the Curvelet transform.Then,further attenuate the interference factors using the nonlinear threshold function designed in this paper.According to the application and analysis of actual data,this method can effectively remove the resonance interference induced by electrical poles while properly protecting effective signals and can significantly improve the signal-to-noise ratio and resolution of the denoised data.Therefore,the method proposed in this paper is effective.

This paper focuses on the application of the 2D inversion of magnetotelluric data that bear terrain information based on an unstructured adaptive triangular mesh. An adaptive unstructured triangular grid can be used to accurately simulate undulating terrain and complex geological structures. The adaptive unstructured triangular grids for magnetotelluric forward modeling are automatically refined using the a posteriori error estimation with the finite element solution, which ensures the accuracy of the model response. As for adaptive unstructured triangular grids for magnetotelluric inversion, fine mesh generation is adopted for the inversion target areas, while coarse grid generation is utilized for the boundary areas of the model, thus reducing unnecessary inversion parameters on the premise of satisfying the inversion accuracy. According to the inversion of an undulating-terrain model of land and an undulating-seabed model, the accuracy and applicability of the algorithm are verified and the algorithm can be used to image the multi-scale structures under the undulating terrain of land and seabed. Then, the method was applied to the inversion of the measured data of the Houshan area in Karamay. As a result, the resistivity structure obtained through the inversion was consistent with the geological data and the results obtained through the nonlinear conjugate gradient inversion.

By collecting and analyzing the heavy metal elements insurface (0~20 cm) and deep (160~200 cm) soil samples in southeastern suburbs of Beijing, the distribution characteristics of elements in soil in this area were ascertained.The spatial autonomy of heavy metal elementswas explored by establishing a semivariogram model. The enrichment characteristics of elements in surface soil were discussed,as well as the correlation of the enrichment coefficient. On this basis of the research, the significant enrichment areas of heavy metal elements are divided, and the reasons for the enrichment are explained and analyzed in depth.The results show that:The content levels of Cd, Cu, Hg, Pb, and Zn in surface soil of the study area are significantly higher than those in the deep layer, with a gap of 1.2 to 3.9 times. Compared with soil’s heavy metal content in Beijing and China,, the soils in the study area is relatively rich in Cd and Hg. As it was affected by many factors such as the source of soil-forming parent material and human activities, the spatial autocorrelation of As and Cr in surface soil is strong, and the spatial autocorrelation of Cr in the deep soil is weak. The spatial autocorrelation of other elements in the surface and deep layers is medium. As, Ni, and Cr in the surface soil are weakly enriched.But Cu, Pb, Zn, Cd, Hg are strongly enriched, and Hg is the most enriched. Based on the enrichment coefficient, five significant enrichment areas of heavy metal elements are delineated.The division of this area clearly reflects that human life, agricultural planting, and industrial production are important factors that cause the accumulation of heavy metal elements in surface soil.Therefore, it is necessary to pay close attention to the distribution of soil elements in human settlements, agricultural planting areas, and industrial enterprise distribution areas. The purpose is to prevent the deterioration of the soil environment and ensure the safety of the ecological environment.

Selenium (Se), one of the trace elements essential to human body, plays an antagonistic role toward the toxicity of heavy metals. The most important, safe, and feasible way for human body to take Se is to transform Se via food chain. This study collected and analyzed 30 groups of samples of rice seeds and corresponding root soil from the natural high-quality Se-rich farmland that is widely distributed in Libo County. Based on this, this study evaluated the edible safety of rice, studied the selenium content in the rice-root soil system, and investigated the influence of the physical and chemical conditions of soil on rice's absorption and transport of selenium, aiming to provide a scientific basis for the development of Se-rich agriculture in the study area. The results are as follows. Most root soil of rice in the study area is Se-rich, with an average Se content of 0.41×10^-6. The rice in the study area has an average w(Se) of 0.030 7×10^-6, and green and safe rice accounted for 70%. For the root soil of rice in the study area, there is a significant positive correlation between w(Se) and w(Fe₂O₃), w(Al₂O₃), w(MgO), and w(organic matter), and there is associated relationship between w(Se) and some heavy metals including Cr and Cd. There was a significant positive correlation between Se content of rice seeds and that of root soil. By contrast, there is a significant negative correlation between the Se enrichment coefficient of rice and the contents of Se, As, Cd, Cr, Hg, Ni, Al₂O₃, Fe₂O₃, and organic matter in root soil. The results indicate that the absorption and fixation of Se by the organic matter and Fe-Al oxides in soil reduce rice's absorption and utilization rate of selenium. The negative correlation between Se enrichment coefficient of rice and the heavy metal contents of root soil suggests that Se may play a certain antagonistic role toward the absorption and transport of heavy metals in the soil-rice system. The study area is rich in Se-rich farmland resources, yet there is a risk that the contents of Cr and Cd in rice slightly exceeds relevant standards. Therefore, it is necessary to pay attention to the ecological effects of heavy metal elements in the development of Se-rich agriculture in the study area.

Surface soil samples in Yaling Town, Yichuan County -Xiaodian Town, Ruyang County in Luoyang City were collected and analyzed to study the selenium (Se) speciation and its influencing factors. The study results are as follows. Existing Se in the surface soil of the study area mainly occurs in humic acid, residue, and strong organic states, while the sum of Se in water-soluble and ion-exchange states only accounts for 2.70% of total Se in the surface soil. Therefore, the Se in the study area shows the characteristics of the low content of water-soluble Se and a significantly high proportion of organic Se in total Se. The Se speciation in the surface soil is affected by the total Se content, pH, organic matter content, and type of soil. Specifically, the proportion of bioavailable Se in alkaline soil is significantly higher than that in neutral and acidic soils, and the bioavailable selenium content increases with increasing soil pH. Especially, the organic matter content in the soil has the most significant effects on organic Se but has no significant effect on bioavailable Se. For different types of soils, the proportion of the sum of Se in water-soluble and ionic-exchange states in total Se is in the order of red clay>paddy soil>brown soil>skeleton soil>fluvo-aquic soil>lime concretion black soil.

This study mainly analyzes and summarizes the relationship between the apparent resistivity and chloride ion concentration in the process of determining the seawater intrusion boundaries of suspected seawater intrusion areas in Qinhuangdao coastal areas using results obtained by the high-density resistivity method. Firstly, this study conducted the statistical analysis of the corresponding relationship between apparent resistivity values obtained through resistivity logging in different geological zones and the chloride ion concentration obtained from water samples collected from corresponding wells. Based on this, the correlation between them was obtained through mathematical analysis, and then the corresponding linear relationship between them was determined. Finally, seawater intrusion areas in the study area were delineated using this relationship combined with the measurement results obtained by the high-density resistivity method. The research process and the final linear relationship will provide experience and methodological guidance for the follow-up work in similar regions.

Prestressed Concrete Cylinder Pipe (PCCP) is used in the Huining section in Beijing in the middle route of the South-to-North Water Transfer Project.After having worked for a long period,the PCCP pipelines have successively suffered the damage of wire breakage,concrete cracking,and local uneven subsidence.Aiming at the common engineering geological defects of the PCCP pipelines used in the Huining section,this study carried out shallow seismic tests based on the high-density seismic imaging exploration and the Rayleigh wave method.As a result,the physical properties of the PCCP and cushion areas were obtained,accurate troubleshooting of the fractures developing on the pipe wall and geologically uncompacted areas were performed, thus providing valuable experience for the investigation of the damages to PCCP.

There are many small coal mine goaves in Huazi Town-Xidayao Town in Dengta City, Liaoyang City, Liaoning Province. They are distributed in villages and towns and their surrounding areas, posing great threats to the ground buildings and resident life. Furthermore, the vegetation around the mining area is sparse, and a large amount of coal slag has been piled up at will, which causes serious damage to the ecological environment. However, owing to the limitations of a single geophysical method, it is difficult to completely eliminate interference and observation errors through the goaf investigation using a single geophysical method. Based on the selection and exploration of geophysical methods from the aspects of anti-interference and effectiveness, this study conducted the coal mine goaves in the study area by applying the geophysical prospecting methods including gravity survey, high-density resistivity method, and shallow seismic reflection method. As verified through drilling, ideal results were achieved.