we conclude and sum up on the character of the Gravity and magnetic field in the project on the Hebei province iron ore resource potential evaluation and metallogenic prediction in this paper.The larger positive aeromagnetic anomalies are mainly reflected by the emergence or hidden intrusive batholith; A larger area of distribution of lower and positive magnetic anomalies are mainly reflected by the acidic volcanic rocks in the Archean metamorphic rocks or the edge of the basement uplift zone where the sedimentary-metamorphic iron ores distribute densely; The negative magnetic field is always reflected in the Upper Proterozoic, Paleozoic carbonates and Mesozoic acidic volcanic-sedimentary rocks;The higher, larger gradient, or the local magnetic anomalies associated with the negative may be a reflection of the magnetic iron ore.The magnetic iron ore are mainly distributed in the gravity gradient zone or abnormal distortions and the border between the positive and negative anomalies From the features of gravity, field,where they are closely related to the strongly-deformed geological structure. We can make a realistic geological interpretation only by deep geological analysis on the gravity and magnetic field and comparison analysis combined with the identification marks built in the typical deposit.

In order to search for concealed ore deposits, the authors carried out prospective survey of mineral resources with Tong'an-Xiaoniuchang area of Sichuan Province as the study area. The integrated geophysical technique composed of gravity survey, aeromagnetic survey, high accuracy magnetic prospecting on earth's surface and IP method is put forward for the exploration of mineral resources in southwest China. It is shown that this combined technique can delineate useful geophysical anomalies for determining the main working area.

Exemplified by typical Pb-Zn polymetallic deposits in Guangdong Province, the authors studied the content characteristics of cadmium in various mining areas and the distribution characteristics of the cadmium content and w(Zn)/w(Cd) ratios in sphalerite from different types of ore deposits. The results show that different geochemical backgrounds in different mining areas have exerted great influences on the enrichment degree of cadmium. In various mining areas, Cd and Zn show correlation or even strong correlation, suggesting that they had similar geochemical characteristics during the ore-forming process. The superimposition of high cadmium content and low w(Zn)/w(Cd) ratios mainly occurs in the distribution areas of known Pb-Zn polymetallic deposits, and the enrichment degree of cadmium somewhat decreases in all directions. The enrichment coefficient of cadmium and w(Zn)/w(Cd) ratios in sphalerite from different types of ore deposits show obvious ladder-like variations, which were not only controlled by the temperature and color during the ore-forming processes of different types of sphalerite but also closely related to silver enrichment in the mining area. This study provides scientific basis for understanding distribution characteristics of cadmium and making geological evaluation of cadmium deposits in Guangdong Province.

Au, Ag, Cu polymetallic deposits (ore spots) were discovered in succession in Dongxiang volcanic basin. According to geological and geochemical characteristics of typical ore deposits in the basin in combination with 1:200 000 regional geochemical data and geochemical anomaly sectors delineated by 1:50 000 soil survey, the authors estimated the quantity of concentrated metallic resources in the basin and delineated promising ore-prospecting targets.

Using the results of 1:200 000 geochemical exploration, this paper described the geochemical characteristics and regularity of of metallogenic elements distribution in Yukai area,and discussed the key elements that should be selected, such as Ag, Au, Pb, Zn, W, Mo and Sn. This paper sums up the spatial and temporal distribution regularity of elements dispersion or accumulation in order to provide geochemical theoretical basis for the prospecting of regional mineralization. The target areas for further exploration are delineated, which include 8 GradeⅠ, 5 GradeⅡ and 3 Grade Ⅲ prospective areas.

This paper presents the findings from studying the typical microbiological indicators based on the theory of edaphic microbe applied to oil and gas exploration. The applicability of edaphic microbe in the oil and gas exploration is justified by the significant difference between the microbe amount in the oil and gas field and that in the background field and between microbial population in the oil field and that in the gas field. The study indicates that methane reducing microbe, butane reducing microbe, obligate hydrocarbon reducing microbe and sulfate reducing microbe all show obvious higher concentrations in the oil and gas field, except for the obligate hydrocarbon reducing microbe in the gas field and the methane reducing microbe in the oil field.

In this paper, geological environments, ore-control conditions, ore body shape characteristics and utilization values of contact-metasomatic type, hydrothermal type and sedimentary-metasomatic type iron deposits are discussed briefly. Based on studying the Za-Ha double component parameter diagram and the inverse fitting of Pingtai magnetic anomaly, the authors hold that Pingtai anomaly is likely to indicate a magnetic body with steep attitude. The gravity and magnetic correspondence analysis shows that the Pingtai gravity anomaly and the magnetic anomaly are not of the same source, and Pingtai anomaly is not the manifestation of a sedimentary-metasomatic type iron deposit. According to the CSAMT results, the evidence of magmatic activity in Pingtai area was found, so that there exist some necessary conditions for the formation of contact-metasomatic type and hydrothermal type iron deposits in Pingtai abnormal area. Comprehensive geological-geophysical data suggest that Pingtai anomaly is the product of a contact-metasomatic type and hydrothermal type iron deposit.

In order to improve the prediction precision through the magnetite layer,solve some drilling problem and determine whether the ore-bearing layer have it or not.This paper considers that we can use the observation of precision magnetic field on exploration line,the measured of core magnetic parameters.By magnetic parameters and drilling logging results for forward calculation,from this we can obtained surplus magnetic anomaly and determine whether the ore-bearing layer have it or not,consequently carry out prediction.The author in the prediction process with adopting:①Maximum residual magnetic strength and magnetic susceptibility;②Average magnetized strength and magnetic susceptibility for Forward Modeling.These can get some actual effect,putting some Suggestions for the drilling problem in the magnetite core area.

Exemplified by the exploration of a certain iron deposit in Indonesia, this paper deals with the effectiveness of the audio frequency magnetotelluric sounding (AMT) method in search for concealed iron deposits. In combination with the magnetic method, the low resistivity body of the AMT method was utilized to delineate the concealed magnetite body. The results provided geophysical basis for drill hole design and mine development and achieved good exploration effect in international commercial exploration.

During the geothermal exploration in Longmenxishan of Luoyang and Luoyang basin, such integrated geophysical methods as audio frequency ground electric field ΔU measurement, radiometric α measurement and IP sounding were employed and, as a result, four hot water wells of concealed faulted structure type were successfully determined, in which the highest temperature reached 98.5℃, and the water quantity was as high as 96 m³/h, suggesting the important role of geophysical methods in search for hot water of concealed faulted structure type. The genesis of the high temperature geothermal wells is tentatively discussed in this paper.

Geochemical characteristics of Yunling granodiorite in the Damaidi Sn ore district were studied in this paper. SiO₂ content varies in the range of 60.25%~66.44%, 64.41% on average; K₂O content is 0.37%~4.39%, 3.07% on average; w_K2O+w_Na2Ocontent is 3.44%~11.47%, 5.92% on average. ACNK of the rock is 2.62 on average. The granodiorite belongs to the high-K calc-alkaline and aluminum saturation series, characterized by the depletion of Nb, Ta, Sr, P, Zr and Hf. Based on trace elements diagrams, the authors found that there exist obvious magmatic differentiation and negative Eu anomaly, suggesting that Yunling granodiorite belongs to syncollision granite.

The structural characteristics of the regional geochemical field is an important factor in the appraisal of geochemical anomalies. Based on background content of elements and degree of anomaly development in the region, this paper puts forward the simple and clear method for classification of the structures of geochemical fields, divides the regional geochemical field into four basic structural types and, exemplified by Guangdong Province, and tentatively discusses the ore-prospecting significance of the major combinational types. Utilizing the background-anomaly structural classification, we can observe carefully the structural characteristics of regional geochemical field in relation to mineralization. The method is simple and practical, and hence serves as an effective means for rapid delineation of ore perspective areas or ore-prospecting targets.

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

Mesh techniques were studied for the reason of large computational domain and model complexity in three-dimensional finite element modeling of electrical well logging. The authors employed a radial grid with parallel tri-prism to improve mesh quality and reduce the number of elements; Accurate element integration of parallel tri-prism was implemented by an affine transformation in order to shorten elements integral computational time; In combination with the unstructured mesh techniques, modeling under complicated condition was implemented. The computational efficiency and accuracy of the authors' schemes were examined by numerical experiments of several synthetic models. The modeling results under different situations are discussed.

Based on the expression of ground layered media on the surface magnetic dipole field derived by A. A. Kaufman, the authors deduced frequency-domain airborne electromagnetic field's expression for magnetic dipole source. Using two-layer and three-layer typical earth model, the authors studied electromagnetic response at different flying heights. Calculations show that the changes of the flying height affect directly the electromagnetic response's value of points measured.

Based on comparing the major performances of typical aircrafts that are used or could be used by the fixed-wing airborne time-domain electromagnetic system, this paper analyzed their modification factors and economic factors. ATEM designers can use the synthetic cost-effectiveness ratio to determine the proper aircraft platform for the development of a new airborne time-domain EM system.

With high resolution for shallow exploration, Ground Penetrating Radar (GPR) provides an significant means for exploring typical geological structures like loose coal seam and goaf in the coalfield combustion area. However, it is difficult for GPR to distinguish various kinds of burning geological structures and delineate the key combustion area because of shortage of theories. Based on electromagnetic wave theory, the authors conducted forward simulation of the geoelectric models of typical burned coal in the coalfield combustion area by using Finite Difference Time Domain (FDTD). The radar response characteristics of numerical computation indicate that serious diffracted waves appear from the part of loose collapse coal seam, and reflected waves from the top of the cavity have high energy and are continuous. Forward simulation and field test demonstrate that, with GPR, we can distinguish the loose degree of the burning coal seam and delineate the key combustion area so as to reduce the cost of fire-fighting. This is of great significance for safe combustion mining.

Because demagnetization reduces magnetic anomaly amplitude and distorts the shape, it affects the accuracy of geological results inversed and interpreted by magnetic data. Exemplified by a horizontal and theoretical 2D cylinder model, this paper simulated the magnetic field in consideration of demagnetization and by using the finite element method and studying the influence of demagnetization on magnetic anomaly. When the magnetic susceptibility k is greater than 1.0 SI, the anomaly maximum deviation reaches up to 1 300 nT and the relative deviation is more than 30%, whether demagnetization is considered or not. It is thus concluded that the remarkable influence of demagnetization must not be ignored. Besides, the magnetic data inversion conducted in the Galinge iron mine of Qinghai shows that ignoring the demagnetization will underestimate the size of the inversed ore body and mislead the drilling design and resource reserves estimation.

With the development of converted-wave exploration technology, multi-wave multi-component seismic exploration methods have been applied more widely. According to the metal model research, the receiving and processing method of multi-wave and multi-component seismic data is discussed and studied in this paper, mainly aiming at such special technologies as separation and noise reduction of multi-wave data, common conversion point gathering, NMO and migration method. The data receiving methods and processing techniques are of great significance for further application of converted-wave seismic techniques to metal ore body exploration.

In civil engineering project accounting and completion acceptance, the detection of the lengths of one-dimensional good conductors such as anchors and bolts is very important. The problem can be solved ultimately as the length can be accurately measured by utilizing the mise-a-la-masse method while the electric field distribution in a parallel hole (test hole) is tested at the flanking region. Theoretical analysis and physical simulation test in tank indicate that the relative distance between the bolt and the hole and the parallelism have tiny influence on the accuracy of the bolt length. The irrelevant good lateral conductor also only has slight interference on the result. Several bolts around the test hole can be measured simultaneously. This effective method for geophysical prospecting may be popularized to the exact length detection of the similar good conductors as reinforcement cage.

The requirement for relative amplitude preservation of seismic data has become higher and higher. However, the techniques and procedures of seismic processing are mainly focused on structure imaging, but their effects on amplitude are often ignored, so the processing results are often badly amplitude-preserved. Based on real and model data, this paper has analyzed the characteristics of amplitude preservation of surface wave suppression, geometrical spread compensation and predictive deconvolution techniques. On the basis of amplitude-preservation analysis, the optimized processing methods and procedures are proposed. The analytical result shows that the amplitude features of seismic processing results can be preserved better.

The main factors which influence the absorbing effects of the perfectly matched layer (PML) method are the thickness of absorbing layer and the attenuation coefficient. Based on the numerical simulation of the seismic wave field, the author discusses the impact of the thickness of absorption layer and the attenuation coefficient on the absorption effect. The results show that, under the condition of constant attenuation coefficient, the larger the thickness of the absorption layer is, the weaker the boundary reflection becomes. The absorption layer thickness of 12~20 traces is fairly appropriate. When the thickness of the absorption layer is smaller, the boundary reflection gets more and more weaker or even becomes zero with increasing attenuation coefficient. Nevertheless, if the attenuation coefficient is further enlarged, the boundary reflection will gradually appear again. Therefore, we must pay attention to the choice of attenuation coefficient in practice. The attenuation coefficient is generally between 500 and 2000. If the attenuation coefficient is larger than 3000, the absorption effect is not satisfactory.

According to the residual static correction, this paper has discussed the application of statistical Monte Carlo method to residual static correction which is computed by the method of maximal energy of reflected wave. The study included the detailed description of Monte Carlo method and the method of maximal energy of reflected wave, the discussion on the way of applying Monte Carlo method in residual static correction exemplified by some practical application. As a result of processing seismic data with Monte Carlo residual static correction, the residual static state has been corrected. Based on a comparison between Monte Carlo residual static correction and other residual static corrections, this paper demonstrates the predominance of Monte Carlo residual static correction. Furthermore, Monte Carlo residual static correction can solve obvious residual amount without phase shifting. These results show the dependability of Monte Carlo residual static correction.

In the study of reservoir prediction, the sonic logging curve is easily affected by various factors and cannot reflect the characteristics of the reservoir, especially in some complex areas. In view of this, this paper puts forward a multi-curve blend method that uses natural gamma, natural potential and resistivity curves in different layers to reconstruct a new pseudo acoustic curve which can not only better reflect the lithology but also keep the consistency of the time-depth relation. The result of stochastic inversion can highlight the difference between the reservoir and the surrounding rock and greatly improve the vertical resolution and lateral continuity of the impedance inversion profile.

For the construction of the airborne geophysical test site in China sponsored by National 863 Major Projects,the authors carried out a detailed investigation of airborne geophysical tests conducted abroad,and summarized particularly the site selection requirements,the construction scheme and its application to "Reid-Mahaffy Airborne Magnetic and Electromagnetic Geophysical Test Site in Ontario,Canada.The investigation provides an important inspiration for the construction of the airborne geophysical test sites in China.

Researches on the soil data of ecological geochemical environment in Zhanhua winter jujube growing area show that some important factors such as distribution, transform rule and modes of occurrence of beneficial and harmful elements in soils affect Zhanhua winter jujube quality and food safety. The elements such as Mo, Cd, Co, Hg, S, N and Se have the great influence on the quality of the winter jujube, and high content of Mo, Cd, Co, Hg and S, especially Hg, S and Cd, will reduce the fruit quality. Where these elements reach a certain content, they will severely reduce the fruit quality. On the contrary, the elements N and Se can improve the fruit quality of the winter jujube. It is suggested that the increase of the effective state content of Fe, K and water-extracting Se or decrease of the effective state content of B, Cu, P and N is favorable for the improvement of the winter jujube quality. The results obtained by the authors indicate clearly the way forward for fertilizer application and field management in growing winter jujube.

A soil gas radon survey was performed on a large scale to determine the distribution of radon in soil of Zhuhai City in Guangdong Province by means of a portable radon monitor of a semiconductor alpha spectroscopy. The survey sampled 469 sites covering an area of more than 100 km². The average of soil radon concentration in the soil depth of 0.6 m is 55.94 ± 58.54 kBq/m³ in Zhuhai urban area, whereas the concentration is 7.14±8.75, 37.64±25.92, and 151.25±196.23 kBq/m³ in the Quaternary sediments, the mixtures of sediments and weathered grain of granite, and the weathered granite in Doumen District, respectively. The high radon potential areas are located within biotitic granites and new industrial districts, as indicated by the strong correlation between the radioactivity level and geological lithology. The mean value of soil gas radon concentration in Zhuhai urban area (ZUA) is about ten times as high as that in Guangzhou, Quanzhou and Jinjing City. The results show that Zhuhai area has higher radon potential, and hence protective measures against radon should be taken into account.

As ground fissures are characterized by varied geneses, small width and special distribution, the utilization of Ground Penetrating Radar (GPR) for ground fissure exploration can hardly attain ideal exploration result. Exemplified by relatively good waveform images obtained in GPR exploration of ground fissures of three different geneses (underground mining-out, active faults and groundwater over-exploitation), this paper describes the working procedure from antenna arrangement, survey line deployment to data processing and image interpretation, and sums up GPR waveform characteristics of ground fissures of different genetic types. Drilling and trench verification shows that the exploration results of GPR are accurate. The GPR exploration can accurately reflect the development situation of ground fissures in depth and detect new ground fissures, thus providing scientific basis for analyzing the genesis and mechanism of the ground fissure.

Starting with algorithm designing, training image,and practical application,the authors analyzed multiple-point statistics research trends both in China and abroad.On such a basis,the core principles of the main four MPS algorithms,their applicable ranges and advantages as well as disadvantages were analyzed,so as to forecast the trend of reservoir modeling.Multiple-point geostatistics is an international forefront research tool in stochastic modeling;nevertheless,as the algorithm is not yet mature,it should be further improved.On the basis of previous researches,the existing problems of the multiple-point geostatistics that need to be modified and the direction of the processing of training images are proposed,such as suitable processing of training image,choice of similarity methods,choice of standardized data,smoothing,coupling among algorithms,and expansion of the simulation extent for fractured-vuggy carbonate reservoir.In order to improve the usage of multiple-point geostatistics for reservoir stochastic modeling,we should spare no efforts to increase the simulation area,improve simulation accuracy,expand the scope of simulation of reservoir types,save simulation time and improve simulation efficiency.

The most important problem in interpreting multi-wave seismic data is multi-wave calibration and contrast, in which the extraction of the reflection coefficient and the selection of the wavelet are most critical. However, Zoeppritz equation is extremely complex and does not have intuitive physical meaning, and hence it is difficult for this equation to receive a direct application. This paper therefore makes a detailed description of five approximate formulae, based on analyzing the suitability of six models with the variation of the angle of incidence. It is concluded that the approximate formula Aki&Richard generally has better adaptability.

The present situation of the service and sharing of geophysical and geochemical data and the sharing ideas as well as the realizing technologies are described briefly in this paper. The service and sharing of the soil reference value spatial database are used as a practical example to explain the publishing technology of dynamic databases with the help of Arcgis Server.

In order to solve the problem of multi-source data display and analysis,the authors studied and developed the airborne geophysical spatial data display platform according to the spatial characteristics of the airborne geophysical data,on the basis of the GIS theory and by applying three-tier architecture,as well as C# language.The platform has the performance of data management and symbol display.This design provides more intuitive information for the interpretation of airborne geophysical data.

Expressway construction in karst developing area, which need exact information of karst. Cross-well seismic computerized tomography is a geophysical exploration method, which use seismic wave to explore the media between wells. It can provide high resolution image of the target. LTI and SIRT are widely used in computerized tomography, improved model method for computerized tomography which's based on that. It consider that a better initial model can improve the accuracy and efficiency of the algorithm, and the distribution of residual error in SIRT can also improve the result of inversion. In some degree,the method improve the result by the numerical modeling experiment.

Time-lapse seismic reservoir monitoring technology is one of the most important technologies that can determine the distribution of residual oil directly. Spatial difference correction for time-lapse seismic data was studied in this paper, aiming at solving the difficulties in the demand and application of time-lapse seismic reservoir monitoring technique in China. Spatial position difference for the same reflection point in different migrated sections caused by the differences in geometry and acquisition orientation results in unreasonable time-lapse seismic data difference, which increases the difficulty and risk of time-lapse seismic interpretation processing parameters. The optimal shifts in x, y and time directions are calculated by 3D cross-correlation between local data volumes from reference data and monitor data. And then the spatial position difference correction can be conducted for monitor seismic data. The comparison and analysis of real time-lapse seismic data indicate that time-lapse seismic spatial difference correction is effective in decreasing 3D nonlinear spatial difference of purposeless repeated acquisition time-lapse seismic data.

For the purpose of obtaining the x-component apparent resistivity of fixed-loop TEM, the authors made the fixed-loop equivalent to some vertical magnetic dipoles so as to calculate the x-component TEM response. The x-component apparent resistivity of fixed-loop TEM can be obtained when channel data of every time are fitted by response of uniform halfspace, and each halfspace resistivity can be regarded as corresponding channel's apparent resistivity. The calculation results indicate that the method is effective and its precision is enough, and hence this tecnique can provide necessary basis for the comprehensive interpretation of two or three components with the fixed loop TEM method.

Combining the application of this method in the exploration of the Yushan large-size concealed bauxite deposit in Henan Province and the exploration characteristics of the covered mining area,this paper discusses the advantage of CSAMT for the pre-survey and survey of concealed bauxite deposits. The exploration depth of the Yushan concealed bauxite deposit in Henan Province is generally 150~700 m, which is so deep that the conventional D.C. electric sounding method cannot meet the needs. The Controlled Source Audio-frequency Magnetotellurics (CSAMT) is a new geophysical technique, and has such advantages as stronger signal, deeper exploration depth and higher resolution. Based on the inversion result of WINGLINK2D and WINGLINK1D, it can accurately reflect the characteristics of deep ore-bearing rock series, formations and structures, and optimize the layout of the project.

The quasi-analytical method is a means for solving integration equations. To study the three-dimensional D.C. electrical field under surface topography, this paper puts forward the formula of the quasi-analytical theory for the three-dimensional D.C. electrical field under the surface topography based on the quasi-analytical theory for the whole space. The authors divide the anomalous electric field at the surface into two parts, one is the body anomalous electric field caused by the anomalous body, which can be solved by the body integral, whereas the other is the surface anomalous electric field resulting from the interface between the earth and the air, which can be calculated by the surface integral. The authors inferred the body electrical reflectivity tensor and the surface electrical reflectivity tensor separately. The quasi-analytical theory was used to deduce the formula of the quasi-analytical theory under the surface topography. This formula can give us a train of thought for solving the surface topography problem. It can enrich the quasi-analytical theory and promote the forward and inverse modeling of the D.C. electrical field, thus laying a foundation for eliminating the effect of the surface topography.

For the purpose of solving the difficult technical problem of making important breakthrough in deep and peripheral ore-prospecting work of the Tongshankou old mining area, the author mainly used gravity survey in combination with magnetic and electrical exploration to conduct researches on deep ore-prospecting methods and techniques in Tongshankou area. A geological-geophysical ore-prospecting model for this area was established on the basis of the metallogenic regularity of hydrothermal polymetallic ore deposits in this area. The results obtained are of some guiding significance in search for copper, iron, molybdenum and some other kinds of ore deposits related to intermediate-acid intrusive rocks in the middle and lower reaches of the Yangtze River.