Deep-penetrating geochemical technology is gradually making progress in the basin and covered area. In this paper, the authors conducted an experimental study of the Shihongtan sandstone-type uranium deposit by using selective leaching technology of mobile form. Many satisfactory results were obtained. Meanwhile, as the selective leaching technology of mobile form currently has no standard sample for the quality control, the authors tried to insert duplicate samples in the analytical method of analyzing the relative quality monitoring, and the analytical results performed the relative error comparison. It is shown that in general the results of analysis can meet the need of the study area.

Geochemical anomaly study is one of important links in geochemical exploration and is crucial for discovery of effective anomalies. In this paper, the authors made a study of the 1:50 000 soil geochemical survey data from a certain area in Xinghai County of Qinghai Province, and calculated the anomaly lower thresholds of elements so as to draw the anomaly map of single elements and the composite anomaly map by traditional model. Then the authors built complexity of the elements metrics to draw the complexity map of the elements by assigning an abnormal value to each element, and delineated seven high value areas of complexity of the elements, with which the authors analyzed the degree of erosion and made an evaluation of ore-prospecting potential according to the aspect of element combination by map of the factor score through applying factor analysis. It is found that anomaly area of the factor score map is in good agreement with that of the complexity map of the elements. In addition, it is highly consistent with the known mine. The results show that the method of the metallogenic prediction process is reasonable. In combination with anomaly characteristics and field geological survey, the authors delineated two major target areas for further prospecting.

The Buobuza area selected for the study is located in the Qiangtang Plateau hinterland in the western part of the Bangong Co-Nujiang River metallogenic belt. The authors carried out an overall survey of regional geochemical exploration. A comparison of different grades of stream sediment samples shows that -10~+40 mesh is the best sampling fraction here; rarefied test study shows that more than 1/4 km² sampling density is valid for discovering a large deposit. According to the -10~+40 mesh stream sediment results of the overall survey, the authors predict that the periphery of the Duobuza ore district has the potential to find large or superlarge copper deposits, particularly in the upper reaches of the Rongna ditch.

Fine particle total measurement and MOMEO were carried out in Caijiaying area located in the north of Hebei Province. The results show that anomalies delineated by two kinds of methods are quite in accordance with the deep concealed Pb, Zn orebodies with the distance less than 200 m. In the surrounding areas, the anomaly can be indicated effectively by fine particle total measurement. These results show that the fine particle measurement can be used to search for concealed polymetallic Pb-Zn deposits.

Mature and postmature source rock has an extremely low hydrogen and oxygen index, so it is difficult to identify its organic type from a Van paradigm of hydrogen-oxygen index. Nevertheless, organic matter of mature and postmature source rock is formed by the combination of various types of organic matters. The authors developed a distribution function combination method to identify organic type in the mature and postmature stage. The authors first developed a math formula of thermal evolution process, and converted samples from mature and postmature stage to immature and low mature stage. Then the authors built distribution function and synthetic organic matter distribution function of the hydrogen/oxygen index by linear combination method in a mature and postmature stage, and finally determined the type of the organic matter by the linear combination weighting in a mature and postmature stage.

Using the permittivity and resistivity data of 239 measuring points which were collected from seven typical loess profiles in Yanchang, Luochuan and Baoji area of northern Shaanxi, the authors summarized the dielectric and resistivity characteristics of loess, and found that the loess layer and the red soil layer could be significantly distinguished according to their electrical properties. Then the relationship and influence factors of electrical parameters of loess in northern Shaanxi were discussed. With the most detailed Chang-10-well loess section in Yanchang area as an example, the electrical characterization and description of the Chang-10-well loess section were described in detail. In addition, the following three problems were preliminarily explored: the theoretical feasibility for electromagnetic method such as GPR(ground penetrating radar) to distinguish clay layer in the Loess Tableland; whether it's necessary to eliminate the influence of moisture content on electrical parameters; the establishment of a scientific earth-electricity model. The results obtained by the authors provide the theoretical foundation of loess electrical characteristics and the basis of interpretation for electromagnetic profiles and earth-electricity model of loess so as to probe into electromagnetic methods such as GPR(ground penetrating radar) for distinguishing clay layer in the Loess Tableland.

According to the latest high precision 1:25 000 aeromagnetic data with the aid of 1:200 000 gravity data, the authors reinvestigated the faults in Chuzhou-Liuhe area. The results show that the structural framework of the study area consists of NNE, NE, NW trending faults which are the main rock-controlling, basin-controlling and mineral-controlling faults. The structural traces of Tanlu fault (Jiangsu and Anhui section) and Huang-Po deep fault at the center are different from things on both sides, forming unique structure characterized by "trunk" at the center and "branches" on both sides. The authors also discussed the controlling action of the EW, NNE secondary faults on the mineral resources in the east Bengbu uplift, and the evolutionary relations between Tanlu fault (Jiangsu and Anhui Section) and northeast part of Hefei basin.

The Xiongxian geothermal area is located on the Niutuozhen buried hill. The shape of hill, characteristics of faults and positions of igneous rocks usually control the heat flowing and the distribution of reservoirs of the geothermal area. In this study, the gravity and aeromagnetic data were processed by using the method of double spectrum signal decomposition and reconstruction. Then the Euler deconvolution inversion revealed the basement framework and the distribution of high-magnetic geological bodies. Based on the previous study, the authors interpreted heat-controlling faults and igneous rocks. The result shows that Niudong fault and Rongcheng fault are the boundaries of heat flowing as well as the channels, and they also can influence the development of surrounding carbonated facture and vug reservoirs. Igneous rocks are mainly in the southwest of Niutuozhen buried hill, and the retained heat plays an import role in the temperature of strata of the geothermal area.

The Fengheying geothermal field,located in the southeast of Tongzhou District of Beijing with an area of 262.51 km²,is one of the top ten major geothermal fields in Beijing plain.The northeast of the geothermal field is a blank area for geothermal resource exploration and development.In order to reveal the geological conditions of this area,the authors carried out 7 km² gravity survey,4 km controlled source audio-frequency magnetotelluric sounding survey in profiles,and 2 points microtremor.All the geophysical prospecting interpretation results consistently show that a secondary fault of Xiadian fault is developed in Xiji Town.The fault is nearly EW-striking and the fault planes dip southward at 75 °,with the displacement more than 1 km.It is inferred that the further favorable targets for exploration and development of geothermal resources might be on the south side of this fault where the fault may form a good channel for deep hot water,and the water reservoir cap is relatively thick.On the basis of the geophysical results,a exploratory hole was drilled in the favorable targets area,with depth 3588.88 m,water flow 3072.64 m³/d and temperature 92℃.Water quantity and temperature of this hole have all achieved economic mining conditions.All researches show that the northeastern area of the Fengheyin goethermal field has good potential for medium-low temperature geothermal resources.

Currently,horizontal wells can't be performed in acoustic logging in the drilling process,and hence fine time-depth relationship cannot be obtained.When the horizontal wells make landing,the requirement of accuracy of depth prediction is very high.In the region of rapid lateral velocity change,the traditional methods utilize the time-depth relationship of exploratory wells to predict depth,and its accuracy can't meet the requirement.The technology of predicting acoustic logging data based on support vector machine can predict sonic curve in accordance with the existing shale content curve and resistivity curve,making synthetic seismogram and getting fine deep relationship,which could greatly improve accuracy relative to traditional methods.This method was applied to the W5H landing of Oilfield A of Bohai Sea,and the difference between the predicted depth and the actual drilling depth was only 2 m,thus ensuring horizontal wells' successfully landing,and achieving practical application effect.

Classical multiple-point geostatistics based on stationary assumption has shortcomings in non-stationary modeling application.This paper proposes a new non-stationary simulation based on segmentation by using anisotropy.The new method uses rose diagram consisting of different directions' variogram range to quantify characterization of train image's local anisotropy.In combination with multidimensional scaling and K-means,the proposed method can automatically segment non-stationary train image into several sub-regions which are independent of each other.In the sub-region,classical MPS algorithms are used to simulate sub-regions' geological model which eventually form a whole non-stationary realization.Using fracture network modeling as an example,the proposed method simulated and reproduced non-stationary train image perfectly.The results obtained by the authors provide reference for non-stationary modeling of multiple-point geostatistics.

The Ordovician Carbonate fracture-cave reservoir is the major reservoir type in Tahe Oilfield. Improving the “string” imaging accuracy and exquisite depicting the internal characteristic of the fracture-cave bodies are one of the key research problems about seismic exploration in this region, combined with exploration cost, carring out seismic geometry design about the fracture-cave target bodies is very necessary. Through building the three-dimensional cave reservoir geological model about work area, to obtain the migration image illumination energy with these cave reservoir target bodies by using Guassian beam bi-directional illumination technology based on seismic geometry. Under the condition of the same fold about seismic geometry, quantitatively demonstrates different illumination effect of acquisition parameters (putting point on the bin and azimuth) on cave bodies, based on the results to choose the best parameters, providing theoretical guidance for field seismic geometry design.

In the very long geological evolution history, earth surface has undergone multi-period and multistage geological processes, and the distribution of the same element in the same stratum differs or its material source might have come from different matrixes, which results in data histogram presenting a multimodal morphology. Multimodal separation is the basis of differentiating material sources, and helps improve geological interpretation level. The fact that geological data mostly obey the normal distribution (or logarithmic normal distribution) provides mathematical basis for multimodal separation. This paper explains the math principles of multiple matrix sample data separation and uses genetic algorithm as implementation approach to theoretically prove that genetic algorithm has a better effect on multiple matrix sample data separation, and its goodness of fit can be up to 95%. An analysis of practical examples shows that the genetic algorithm can correctly distinguish 2 kinds of lithology of the stratum, which suggests that it has practical significance in geological research.

To tackle the influence of the radon on the airborne gamma-ray spectrometry survey, the authors studied the law of atmospheric radon during the climatic change, and detected that the atmospheric radon change is easily controlled by the meteorological factors, and has great influence on Tc and uranium channel in the aviation gamma spectrum measurement. In consideration of the fact that the radon will be slowly stabilized three hours after the rain, the authors put forward the regularity of the influence of radon on the airborne gamma-ray spectrometry and the measures that should be taken in practical work.

Through the aeromagnetic survey of the power glider in Duobaoshan area, the authors evaluated the function and characteristics of the powered glider aeromagnetic system. The comparison of measured data and the processing analysis of graphic data in different flight directions on the same measuring line indicates that there is no lag and no direction difference in the data, and the three-component magnetic compensation system is relatively complete. The working accuracy is 4.0nT by using the repeated line data as the check data, the inspection data of the same spatial position with the check points can be obtained by means of interpolation and height extension. The demonstration results indicate that the powered glider aeromagnetic system has the characteristics of portability, high efficiency, high adaptability and high precision.

The 2D elastic wave frequency domain 17-point difference scheme is obtained based on the simplified 25-point difference scheme so as to optimize the structure of impedance matrix,reduce required memory and improve efficiency in 2D isotropic media forward.This scheme recalculates partial differential operators in the elastic wave equation,reduces the grid node in calculation process,and constructs the forward matrix equation with optimized impedance matrix.The P-wave and S-wave velocity dispersion formulae are derived,the dispersion curves of different Poisson's ratio are given,and the grid number requirement in each horizontal wave length is given with phase velocity error range being ±1%.The frequency dispersion curve and numerical simulation of the wave field snapshots and seismic records show that the 17-point difference scheme has slightly strict grid spacing requirements, similar accuracy,slightly less computation time and smaller impedance matrix bandwidth in comparison with 25-point difference scheme.

In the study of coal rock elastic wave response characteristics,the influence of axial compression on longitudinal wave,transverse wave velocity and attenuation has not been given enough comprehensive consideration.In view of such a situation,three kinds of coal samples which experienced different grades of metamorphism were chosen from the Pingdingshan No.8 mine.Vertical-bedding samples,parallel-bedding and vertical-face cleat samples,parallel-bedding and vertical-butt cleat samples were prepared to conduct water absorption and ultrasonic experiment.Some experimental results have been obtained:First,in the natural state,longitudinal,transverse wave velocity and quality factor in three directions of the three kinds of coal samples are anisotropic,generally longitudinal,transverse wave velocity and quality factor in two directions parallel to bedding are greater than the corresponding data perpendicular to bedding plane.Second,in the coal rock,the longitudinal and transverse wave velocity increases rapidly with the increase of axial pressure in the early stages.After that,the velocity increases slowly and the wave velocity decreases rapidly until the coal sample is destroyed,the transverse wave velocity is not as obvious as the longitudinal wave.Third,in the three directions,the quality factor increases firstly and then decreases with the increase of stress,and Q_S is generally larger than that of Q_P.Fourth,in coal samples of different metamorphic grades,longitudinal,transverse wave velocity and quality factor differences are more obvious,longitudinal,transverse wave velocity of 1/3 coke is greater than that of coking coal and that of the fat coal.

Tube wave detecting method has a good application prospect in pile bottom cavity detection of rock-socketed pile side and pile core pulling tests (pile body completeness);nevertheless,at present the method is mainly based on the qualitative interpretation of tube wave time section.In view of this situation,the authors,based on the past experience,put forward the utilization of tube wave information (direct tube wave arrival time,center frequency,reflection coefficient) for quantitative interpretation,and application of the combined qualitative explanation and quantitative interpretation,so as to improve the interpretation precision of the tube wave detecting method.The model pile experiment shows that the quantitative interpretation method with tube wave information is scientific and feasible.It can obtain good effect of geological interpretation,improve the foundation pile integrity and overcome the peephole view of core detection.

The authors analyzed the content of Cu,Pb,Zn,Cr,Ni,Mn and Cd in near-surface atmospheric dust-falls in education area,residential area,industrial area,mixing zone and commercial zone in Yinchuan. By using the index of geoaccumulation and potential ecological risk index,the authors evaluated the pollution degree of heavy metals and the ecological hazards caused by them. The results showed that the content of Pb in the mixing zone, industrial area and commercial zone was obviously higher than the soil background. The content of Cr, Ni and Cd in the mixing zone was significantly higher than the background value; Mn content in soil background was the same in various functional areas. Index of Geoaccumulation shows that the pollution degree of heavy metals from high to low was Cu>Zn>Pb>Cd>Cr>Ni>Mn, with the highest being Cu and Zn, whose values reached moderate pollution in the whole sampling period. Pb and Cd reached moderate pollution in the third and fourth sampling periods, Ni and Cr reached moderate pollution in the third sampling period, and Mn didn't cause actual pollution in the whole sampling periods. Heavy metals in samples of dust-falls caused different levels of potential ecological hazards. The potential ecological risk index of Cu, Pb, Cr,Zn,Ni and Mn was slight, but that of Cd in the third and the fourth sampling periods reached strong ecological hazards. In all functional areas, only the mixing zone's potential ecological risk index of heavy metals reached moderate ecological hazard, and all other functional areas belonged to slight ecological hazard classes in each sampling period.

With the rapid development of urbanization, water environment and sediments of many urban rivers have been polluted in China. The Zhouhe River is the largest river in Jixian County, Tianjin, but the river has been polluted over the past 10 years, which made the ecological environment worse. In this paper, the water quality and the pollution of heavy metals in sediments were evaluated for water and its sediments in the Zhouhe River of Jixian County as the medium to provide scientific basis for the comprehensive management of water environment in the future. The research shows that the river water is suitable for agricultural irrigation, but the downstream water is not suitable for agricultural irrigation. The evaluation based on sediment quality standard method shows that Cr, Ni in the sediments have caused moderate pollution, Hg in the upstream sediments has caused serious pollution, and Zn, Cu in the upstream sediments have caused moderate pollution. Results based on the sediment geological accumulation index show that Hg, Zn and Cd in the upper reaches of the river are at the level of Cu, and the intensity of the grade is in the intensity of the country; Cd, Cu, Zn in the upstream sediments are at the level of non-moderate pollution, and Hg is at the level of intense pollution. Comprehensive evaluation of two results show that the major pollutions of heavy metals are Hg, Ni, Cr, and the secondary pollutions of heavy metals are Zn, Cd , Cu in the sediments in Zhouhe River.

In the frequency range of 20kHz ~ 100kHz, the HMT signal has the characteristics of weak strength, low correlation and poor repeatability, which is caused by the interference of human noise in the near surface. In this paper, the authors used higher-order spectrum method to analyze and reconstruct HMT signal, which can effectively suppress Gaussian random noise and raise signal noise ratio. Numerical analog signal and measured data processing prove that the method is feasible. According to the application effect, the method is better than the traditional method in colored noise suppression and practical geological information extraction.

In order to investigate the geophysical parameters of the important ore concentration areas in Anhui Province, the authors studied the anisotropy of rock electric parameters. Selecting sedimentary and metamorphic rocks in Huoqiu ore concentration area, Lujiang-Zongyang ore concentration area, Ningwu ore concentration area and Dongzhi-Jingxian metallogenic belt as study samples, the authors tested the three directions of the resistivity and polarization. The result confirms that the anisotropy of rock resistivity is extremely obvious. It is found that the higher the resistivity, the higher the ratio of the vertical resistivity to the horizontal resistivity. The anisotropy of rock polarization also exists, but it is not obvious. The anisotropy of resistivity exists in sedimentary rock, metamorphic rock and volcanic sedimentary rock. Based on data analysis of rock anisotropic electrical parameters, the authors summarized the anisotropy characteristics of rock electrical parameters, which provides basic data and foundation for the study of geology, the comprehensive understanding of the previous data and the comprehensive interpretation of electrical prospecting.

Seismic source is an important part in the exploration of oil and gas resources and microseismic monitoring.Based on the equations of loading source on pressure source,shear source and centralized source,the authors obtained seismic snapshots in isotropic medium through triggered-grid finite difference scheme simulating and discussed in detail pattern characteristics of wave excited sources so as to choose the most suitable source to save the exploration cost.The authors analyzed in detail the mechanism of excited seismic sources from wave polarization theory of physics and,together with the analytical solution,verified the results of numerical simulation.It is concluded that the force is the controllable factor of obtaining seismic source field,the source used in 3-D fracture media can observe shear splitting,and physical analysis is a kind of verification method for explaining the pattern of seismic wave.

The local search capability of the classical nonlinear programming algorithm is strong, and the genetic algorithm adopts the selection, crossover and mutation operators to perform the search, hence its global search capability is strong, whereas the local search capability of the genetic algorithm is weak. Therefore, a nonlinear programming genetic algorithm (NPGA) was proposed based on the previous studies, which combines the advantages of these two algorithms. Proved by function test, the proposed algorithm could significantly improve the search performance of genetic algorithm. On such a basis, the geoelectric models were established. Finally, the nonlinear programming genetic algorithm was applied to the inversion calculation of TEM. The results show that the proposed algorithm has fast convergence speed and high calculation precision, thus exhibiting good inversion effect.

The electrical source short-offset transient electromagnetic method (SOTEM) has characteristics of strong signal, high resolution, large investigation depth, and less influence by topography and underground structure. It is therefore suitable for the detection of low resistivity body and fine structure. In addition, it is easily arranged and the receiving instrument is light and easy to operate, so it is very suitable for difficult field area with complex terrain. In this paper, the SOTEM method is analyzed theoretically, and the spatial distribution characteristics of the transient electromagnetic response of the layered geoelectric model in different time spans are calculated and simulated. The result shows the superiority of the near field observation. Based on the analysis of the relative error of response between different geoelectric models and the variation characteristics with the abnormal resistivity, the authors investigated the capability of SOTEM for discriminating electrical anomalies. In this paper, the authors have obtained the theoretical judgment formula of SOTEM detection depth, and put forward the commonly used formula of probing depth. At the end of this paper, the application of SOTEM to the detection of the gob in a coal mine in Datong of Shanxi Province is given to illustrate the effectiveness of the method. According to the comparison, the detection results coincide with the drilling information.

The potential karst disease of the airport runway is directly related to the carrying capacity and working life of the airport runway. According to the applied exploration cases of Guangzhou-Baiyun international airport, the opposing coils transient electromagnetic method in karst disease survey is proved to be fast and non-destructive under the background of airport noise and limitation of the site condition. Compared with conventional engineering geophysical prospecting method, the opposing coils transient electromagnetic method can effectively avoid the influence of airport aircraft landing noise while the seismic reflection wave method fails to do so, and it can work under the condition of poor ground while the high density resistivity method can not do so. What's more, it can detect deeper bodies while the geological radar method can not do so. In conclusion, the opposing coils transient electromagnetic method is a new effective detection method for the detection of hidden geological diseases in the airport runway.

Seismic attributes technology is now widely used in seismic prospecting engineering.In this paper,the authors used seismic attributes technology to predict the coal seam thickness in Longdong loess tableland,obtained the seismic prospecting field data in the prospecting area and extracted a variety of seismic attributes from the coal seam reflected wave.Based on the correlation analysis of the known coal seam thickness and the seismic attributes,the authors found that the coal seam thickness has a good linear correlation with seismic spectral attribute.The authors took advantage of the center frequency and amplitude attribute of the seismic attribute to predict the coal seam thickness in the whole prospecting area.The variation trend of coal seam thickness agrees with the coal seam thickness in drill hole,which indicates that coal seam has frequency tuning function and it is feasible to predict the coal seam thickness with the seismic spectral attribute.

Using the Wide Field Electromagnetic Method, the authors ascertained the tectonic framework of the Changsan uplift area in southern North China basin. The relief and the burial depth of the basement, the main distribution of the strata in the work area were found out. The burial depth and the thickness of the low resistivity zone were determined so as to determine the favorable location of the shale layer. Interpretation results were verified by drilling recorder, and better geological achievement was gained. The results of the exploration provide very useful geological and geophysical information for the shale gas 'target' and 'dessert' area exploitation and show clearly the validity of the wide field electromagnetic method in detecting shale gas strata.

The application of comprehensive geophysical methods to the detection of mined-out areas can fully take advantage of multi-information and can also eliminate the technical limitation of a single method so that the goal of effective detection of mined-out areas can be achieved. In this paper, with a coal mine in Yunnan Province as a study case, the authors applied seismic method, high-density DC method and transient electromagnetic method (TEM) to conducting comprehensive geophysical prospecting. Based on the combined analysis of the geophysical response of seismic field, DC field and electromagnetic field, the authors successfully detected the range of the mined-out area in the prospecting district, with the exploration results verified by drilling.

There are several concepts of depth in transient electromagnetic method, including diffusion depth, limit detection depth, effective detection depth and apparent detection depth. In this paper, we conducted the calculation, analysis and application to these different depths based on the method of SOTEM. The diffusion depth represent the diffusion and propagation of the underground transient EM field, the limit detection depth reveals the detectability of SOTEM and the results indicate that the greatest depth will be obtained when the offset approximately equal to the 0.7~1 times of buried depth of targets, and the apparent detection depth can give a estimation of the actual detection depth for a given recording time which have a significant meaning to the field work designing. At last, we proposed a synthetic model and a filed example to verify the feasibility and accuracy of using apparent detection depth to estimate the actual detection depth of SOTEM.