In order to track buried faults, rocks and ore bodies, the authors tentatively applied the directional derivative, tilt derivative and interpolation-cut method as well as some other methods for airborne magnetic survey, and then created a model for comparative analysis in Inner Mongolia. In the application of the tilt derivative to track concealed faults and rock bodies, the interpolation-cut method for tracking concealed magnetic ore bodies seems to be comparatively satisfactory.

Through R-type factor analysis of 1:50 000 stream sediment survey in Mabugang area, Guangdong Province,13 composite anomalies were delineated. Based on characteristics of composite anomalies and exploration evaluation, the authors confirmed 7 prospective areas. According to the geological conditions for mineralization as well as characteristics of anomalies during geochemcial exploration and mineral exploration, No. 4 and No. 11 composite anomalies are considered to be target areas.

The application of the aerosol theory and technology to deep prospecting is the basic problem discussed in this paper. Minerals from the depth can pass through the overburden of the ore deposit and reach the earth's surface. This process is mainly implemented by the transfer of the gas which carries plasmid upward from the depth. The basic condition of this transfer is that plasmid could be stably suspended in the gas and then flow. The aerosol theory suggests that plasmids in the range of 0.1～2.5 μm in diameter are the most stable ones in gas. Plasmids in the smaller or coarser sizes cannot be suspended in the gas for a long time; another point of the aerosol theory is that the solid plasmid which is less than 2.5 μm in diameter cannot be produced by mechanical milling. These two points of aerosol theory constitute the foundation of the view that the deep metal mine could generate aerosol levels plasmid,then the plasmid enters gas to transfer upwards. The aerosol theory and technology were applied in the prospecting test of the Jinwozi concealed gold deposit in Xinjiang. The results showed that,at the top of the No. 210 concealed deposit and above the inclined plane of the deposit,there is an obvious Au anomaly and a satellite elements anomaly,characterized by high anomaly contrast value and large exposed area. This experiment proved that the method of extracting the aerosol plasmid absorbed on the surface soil and then making element analysis has a good ore prospecting effect.

Lead isotopic tracing is a method for identifying the ore-forming materials according to the lead isotope ratios of rocks, minerals and their relationships. This method was used to trace the geogas components of the Wangjiazhuang copper deposit in Zouping, Shandong Province. A comparison of the lead isotope ratios of ores, wall-rocks and soil with those of geogas samples by using ICP-MS analysis shows that the lead isotopic composition of abnormal geogas samples is in accordance with that of ores, suggesting that the lead in abnormal geogas samples comes from deep-buried ore bodies.

The contact zone of Lianshanguan rock body is an important ore-controlling structural zone in the Lianshanguan-Qijiabaozi area. In order to detect the strike and the downward extension of the rock body contact zone and the distribution of radon concentration anomalies in the study area with the purpose of guiding uranium exploration in this area, the authors employed both audiomagnetotellurics and soil radon survey on the basis of the physical-chemical environment. Based on the comprehensive geophysical results, the authors determined the strike and the deep extension of the contact zone and delineated four uranium favorable zones, which provides the information in the depth for uranium exploration. Drilling verification shows that there are two uranium anomalous holes and one mineralized hole in No. Ⅳ section, thus achieving favorable application result.

In order to tap the potential of the Taoshan uranium ore field, the authors conducted integrated geophysical survey in Taoshan area. The inversion result of CSAMT can indicate the characteristics of the faults and the fractured zones in the subsurface, especially the width, depth, strata and lithology of the faults. Magnetic survey can delineate the monzontic granite zone which is closely related to the uranium deposit. A geological-geophysical model was formulated for this ore district and the prospecting target of the uraium deposit area was delineated. It is shown that the results obtained by the authors are valuable for further exploration.

Controlled by the ancient terrain composed of Ordovician limestone, the bauxite deposit is positively related to the thickness of Carboniferous Benxi Formation in the ore-forming basin, and the favorable positions for bauxite enrichment are slope belts, depressions, grooves and karst funnels. As there exist obvious differences between Ordovician limestone and overlying formations in density and electrical properties and between bauxite and surrounding rocks in density, Bouguer gravity anomaly can better reflect the tectonic framework in the study area and the rise-and-fall trend of the Ordovician interface, Bouguer gravity residual anomaly can reflect the occurrence of partially high percentage of bauxite, and the combination of controlled source audio-frequenay magneto-telluric (CSAMT) method and calibration of the drilling can efficiently infer the buried depth and occurrence of basement limestone. The authors have achieved good application result by using 1:25 000 gravity and CSAMT method which combines direct prospecting and indirect prospecting, and the results provide a basis for deploying drill holes.

There generally exists the record of a low-frequency band characterized by low frequency,strong energy and fat wave form in the near-surface micro-logging data of the Tahe oilfield,which usually occurs near the top of the high-velocity layer.The reason for the formation of this special low-frequency band and its influence on the selection of IP well depth are important problems that geologists have to face in seismic data acquisition in this area.The low-frequency band was previously considered to be produced by lithological change,and hence in well depth design,the low-frequency band was intentionally avoided.Based on practical data,theroretical analysis and well depth test,the authors hold that the low-frequency band results from ghosting,and that the IP in the low-frequency band will not change the single gun quality.The characteristics and the formation mechanism of the low-frequency band as well as its impact on the selection of IP well depth are analyzed in detail,and it is considered that the influence of the low-frequency band can be ignored in the IP well depth design.

Based on ten sediment samples collected in the sea areas of Pearl River Estuary and South Yellow Sea, the authors analyzed 67 elements to study geochemical characteristics. The patterns of element abundances and their distributions have been investigated in this paper. The results show that sediments in the coastal sea area mainly originate from terrestrial source and, except for Ca and Sr, the distributions of major elements possess the characteristics of terrestrial materials. A comparison between Pearl River estuary and South Yellow Sea shows that the former is rich in As, Cd, Hg, Sb, Sr, Ca, Rb and C, whereas the latter is rich in Al₂O₃, Zr, Hf, Sc, Rb, Ga, Cs, V, Co, Cr, Cu, Mn, Ni, K₂O, Na₂O, B, Ba and I. A comparison with the element abundances of China's shelf sea shows that the enrichment and dispersion regularities of elements in the surface sediments of the two study areas are different.

The authors explained the application effect of the soil geochemical survey in the tropical arid steppe landscape area of Botswana,exemplified by the prospecting in Tonota-Foley, within central area of Botswana. By using this method, the authors delineated 17 geochemical composite anomalies in Tonota-Foley and found that the sources of anomalies are calcite serpentine, as evidenced by trenching in the typical anomaly areas. It is shown that soil geochemical survey, which is accurate and effective in delineating anomalies, is suitable for the landscape of the central area of Botswana. This method can be extensively employed in similar landscape areas of Botswana.

The breakthrough pressure is the key parameter in evaluating the sealing capabilities of mudstone caprock. Through the correlation analysis of measured core pressures and logging data, the equation between the acoustic transit time and the breakthrough pressure was established and, on such a basis, the vertical and plane variation characteristics of mudstone breakthrough pressures in the Upper Paleozoic of south Ordos Basin were studied. The result showed that pressure values in the west and north areas were higher than those in the south and east, and pressure differences in the east-west direction were remarkable. Due to high deposition rate and clay content in the wide lake facies developed from early Middle Permian and rapid subsidence of basin from Late Triassic to Early Juassic, liquid discharge of mudstone in the Upper Shihezi Formation was blocked during the overlying compaction that caused abnormal high pressures and relatively low breakthrough pressures. Before and during the deposition of Lower Dhihezi Formation, high breakthrough pressures were distributed in arc along Qingyang, Yanan and Yichuan, low pressures were in the SW direction of the study area, while from the Upper Shihezi Formation period, low pressure distribution direction changed gradually southeastward and high pressures transferred from the east and northeast of the study area to the west and southwest.

By collecting and sorting out previous physical data from regional and district geophysical exploration to establish petrophysical database of Henan Province, this paper provided basic data for gravity survey, seismic exploration and geological research. On such a basis, mathematical statistic analysis was done for the density data of totally 33 070 rocks within Henan Province, and the density statistics of total rocks of the whole province were presented. It is found that there exist varying degrees of differences between big groups, groups and subgroups, and these differences can be used as references in geological survey of Henan Province.

Seismic wavelet is changed in the wake of stratigraphic depth access.The improved S transform in combination with spectral modeling method can overcome time-varying seismic wavelet and avoid the complex window dimension problem.Spectral modeling in the time-frequency domain can well adapt itself to the assumption condition in that the seismic data are smooth and serve as steady signals.Spectral modeling is processed in time-frequency domain,which can overcome time-varying wavelet and improve seismic resolution.A comparison of the effects of the seismic data processing shows that the method can effectively broaden the frequency band and improve seismic resolution.

Random noise can be effectively attenuated based on conventional combination of curvelet transform and total variation technology.This combination technology can reduce the pseudo-gibbs effects and the aliased curves resulting from using curvelet transform,but this method is not conducive to the fidelity of seismic data processing.In this paper,a random noise attenuation method is put forward based on multi-scale and multi-direction improved Donoho thresholds,This improved combination technology can very effectively overcome the disadvantages of conventional combination technology and better preserve the signal of seismic data.When this method is used to attenuate random noise,we must choose appropriate threshold factors at every scale and in every direction,and it is unlike conventional technology which only chooses one fixed proportion threshold factors of all curvelet coefficients.Theoretical model and real data processing results show that this technology can maximally preserve the signal of seismic data,so it has a good prospect in the seismic data processing.

Marine seismic acquisition often meets with some transitional zones,which are very complicated and have rapidly changeable water depth that could sometimes reach 300 m in depth;meanwhile,lots of islands and reefs are spread there.It is too risky for the marine steamship to conduct work,and OBC fails to reach the work depth.Therefore,there are some seismic data gaps in these zones.The Z700 ocean bottom node could acquire seismic data from the shallow water up to 700 m in depth and is capable of filling up the data gaps and linking up data obtained form the whole region,thus favorable for the integration of the oilfield exploration.

As the logging instrument is placed near the field source, the borehole magnetic data are likely to be affected by the internal magnetic field when the drill hole penetrates the magnetic body. As a result, the useful signal is often suppressed by strong jamming and not easy to identify. Therefore, it is important to find a method which can identify the weak signal through data preprocessing. In this paper, the methods for ground survey, called total horizontal derivate of tilt-angle and analytical Signal Amplitude, were used in borehole magnetic survey. The authors proposed vertical derivative of tilt-angle through coordinate transformation and a new method called Equalized Analytical Signal Amplitude. Through data processing of the model, the authors point out that the two kinds of methods can both identify the magnetic body and give the boundary information. The authors also give a standard to choose a suitable window to calculate the Equalized Analytical Signal Amplitude. The two kinds of methods were applied to Jiangsu ZK002 borehole magnetic data preprocessing. The vertical derivative of tilt-angle enlarged the interference of data, wheres the Equalized Analytical Signal Amplitude uses normalized method to identify the weak signal and suppress the interference. The Equalized Analytical Signal Amplitude is also well consistent with the results of magnetic susceptibility logging and the borehole data in ZK002.

The characteristics of wavelet can be used to extract important information of airborne gravity anomaly. In this paper, the authors established the geological model using wavelet analysis theory, and then discussed the corresponding relationship between geological body boundary and wavelet magnitude. Based on the airborne gravity data obtained in some sea areas of China, the authors used the maximal value of wavelet magnitude to identify the fracture information in comparison with the airborne Bouguer gravity anomaly and its directional derivative. The result shows that wavelet magnitude can identify the fracture, especially in the area with fuzzy result of the airborne Bouguer gravity anomaly and its directional derivative.

Research was carried out under the special conditions of the Tibetan Plateau, with the consideration of the time-costing feature of regional geochemical follow-up. The portable XRF spectrometer was used in the research, and the instrument was calibrated and checked for the stability. The sample particle size of -160 mesh for sample processing and powder samples was determined. The result of in-situ experiment, which was conducted in Yazhuo anomaly follow-up zone, is basically in accordance with the conclusion of laboratory analysis. This is an in-situ analytical method, which can quickly provide analytical results and effectively shorten the work period for anomaly follow-up.

The basic principle, measuring method, data acquisition way and data processing and interpretation method are described comprehensively in this paper, which helps understand in detail the practical application of the electromagnetic flow rate logging instrument. During the mixed pumping (injection) test in hydrogeological exploration, the performance of the electromagnetic flow rate logging can acquire the data obtained by stratified pumping (injection). The essence of the electromagnetic flow rate logging lies in measuring the induction data of the flow velocity, which can be divided into the natural static state standing water level measurement and the pumping (injection) dynamic standing water level measurement, and the measurement ways include continuous measurement and point measurement. The principles of qualified, depth-determining and thickness-determining interpretation are as follows: On the basis of the base value of the instrument, the increase of the amplitude indicates the water gushing bed, the decrease of the amplitude signifies the water absorbing bed, and the invariant amplitude means the confining bed; the inflection point of the curve variation is the reflection of the interface and determines the depth and thickness. During the calculation of the water yield, we should first determine the sensitivity of the instrument in the hole, obtain the velocity value through the reflection value of the aquifer roof, and calculate the water-carrying sectional area of the water drill hole, so as to compute the water yield.

Mathematical morphological filtering, which is a new type of filtering method based on morphological principle, has been applied successfully in various signal processing problems. Based on the principles of the morphological filtering, the authors introduced a new filter structure for noise cancellation characterized by the multiple structural elements to improve SNR (Signal to Noise Ratio) of MT data in this paper. With numerical simulation, the filtering effect of the multiple structural elements mathematical morphology filtering is demonstrated,which indicates that the multiple structural elements mathematical morphology filtering has a good performance in supressing the noise at a small scale. The results of curve reconstruction of the real magnetotelluric sounding data and the apparent resistance curve show that the generalized morphological filter can suppress the large-scale noise such as square wave and triangular wave. It is shown that the multiple structural elements morphological filtering has a good application value in the noise suppression of magnetotelluric sounding data.

During the implementation of the project "Deep Exploration Technology and Experimentation (SinoProbe)" in China, the MT instruments MTU-5,V8 and LEMI-417 were used. However, their human-machine interface was based on character, which made it difficult to find useful information and faulty operation during data acquisition. The oscilloscope can display the law of the time-varying electrical signals that can not be captured by visual sense, so the technology is used in the CLP, a magnetotelluric instrument designed by an exploration party, which means its human-machine interface is based on graphics. The GUI is developed with Visual C++ 6.0. Firstly, the display area of the screen is defined. Secondly, the objects of the class CDC (Device Context), CPen, and CBitmap are set up, and the virtual oscilloscope is designed with them. Then the collected data are displayed through graphics. Furthermore, the virtual oscilloscope can be adjusted automatically according to the monitor property. The experiments show that this display method can help the operator analyze the collected data and provide guidance for the next step.

Using the electromagnetic fields of a horizontal electric dipole electric component expression, this paper discussed the E_x and E_φ components which have different amplitude ranges, and propose a new apparent resistivity of wide field electromagnetic defined by E_φ component. The authors also studied the characteristics of the apparent resistivity of wide field. Under the condition of the homogeneous half space, the measurement of E_φ components can expand the field observation sector and reduce the construction cost. Through studying the two-layer model of the forward theoretical curves, the authors have found that the wide field apparent resistivity defined by E_φ component has much smaller observation angle than E_x mode, corresponding to the observed sector where no apparent resistivity curve distortions occur. By calculating apparent resistivity defined by wide field E_φ component of type H and type K model, the authors have found that wide field electromagnetic method is more sensitive to low resistance. The numerical results show that the wide field electromagnetic method also has the near-zone.

Depending on the formula of electromagnetic field data from horizontal electric dipole under the quasi-static conditions, this paper deals with the measurement sector and advantages of electric field r-direction. Through numerical calculation of several typical layered models such as D, G, H and K, the E_r apparent resistivity is compared with the E_x apparent resistivity under 1-D conditions. The result shows that the measuring position has less effect on E_r apparent resistivity. Through numerical calculation of a single anomalous body existent in half-space by using the integral equation method, the E_r apparent resistivity is compared with the E_x apparent resistivity under 3-D conditions. The result shows that the E_r apparent resistivity has a better effect on the edge of the low-resistivity anomalous body.

Based on the basic theory of the electromagnetic field, the authors deduced the wave field extrapolation formula of electric field component in horizontally stratified media. By analyzing the results of numerical simulating and migration imaging using the split-step Fourier method with designed reinforced distribution model and lining thickness model, the authors have reached some conclusions. The split-step Fourier method not only can realize the numerical simulation and migration imaging of two-dimensional non-uniform media, but also has advantages of easy programming and small amounts of calculation. Project real data have tested and verified the effectiveness and practicality of migration imaging using the split-step Fourier method.

Based on data of heavy metals concentrations of 2 300 topsoil samples collected in central Zhejiang Province and regional geochemical exploration conducted in 1987, the authors analyzed the characteristics of Cd, Hg, Pb, Cr, Ni, Cu and Zn concentrations. The concentrations of these 8 heavy metals increase significantly in the industrial districts. Approximately 6.09% and 40.26% of the soil is respectively subjected to moderate to heavy and slight pollution of heavy metals. The distribution of contaminated districts is consistent with the traffic trunk and hardware enterprise areas, and has nothing to do with the geological background, which indicates that the heavy metals are derived from local hardware enterprises.

Based on the principle of Fiber Bragg Grating Sensor,the authors put forward packaging of fiber grating strain sensors,and studied its sensing characteristics with laboratory experiments. Fiber Bragg grating sensors in monitoring geological hazards were studied based on the emplacement of landslide processes and monitoring, and fiber Bragg grating sensors were used to monitor the process of change. In combination with practical applications, the field application examples of grating sensor for monitoring landslides were given. The early-stage monitoring results were obtained and analyzed. Advices are proposed for handling the problems that may occur during the instrumentation.

2.5D DC resistivity modeling was realized by adaptive finite-element numerical simulation algorithm. This algorithm uses unstructured triangular element that is easy to simulate complex topography and inclined interface to subdivide mesh, and utilizes dual weighted posteriori error estimation guide mesh refining process. In the instance model analysis, the authors calculated the DC resistivity response of the layered model and the vertical dike model, which were compared with their analytical solutions respectively. The results show that the numerical solution for this algorithm has high accuracy,and the relative error of the numerical solution is less than 5 percent. Finally, the authors calculated 2.5D geoelectric model apparent resistivity anomaly of undulate topography and corrected the undulate topography by using the comparative method. The contrast between topographic correction results and level terrain results show that the comparative method is effective in eliminating the terrain effect and giving prominence to local geological anomalies.

In this paper, secondary field algorithm was used to study CSAMT two-dimensional forward problem. Forward modeling used finite-element method, and it employs compressed storage and conjugate gradient technique to accelerate the speed of forward algorithm. In addition, topography was added to the forward algorithm. Finally, the algorithm was tested by means of a synthetic model. The test shows promising results.

For understanding the effect of different grid spacing intervals of DEM on terrain correction accuracy of the triangular-element method, the rectangular method and the average elevation rectangular method, the authors calculated the terrain correction values of 450 stations with different grid intervals of DEM. A comparative study shows that the effect of DEM grid spacing on terrain correction accuracy of the triangular-element method is insignificant, and things are just the opposite for the rectangular method. The authors also divided terrain correction ranges into 10 intervals and calculated the corresponding terrain correction values. Statistics show that the 45% and 30% residuals are mainly distributed in the ranges of 50～200 m and 200～500 m, and it is therefore proposed that the elevation data grid density in the ranges of 50～200 m and 200～500 m should be increased so as to increase the terrain correction accuracy.

Time shift,amplitude,frequency and phase difference are main factors influencing time-lapse seismic data processing.The elimination of the time difference is the primary step in non-repeatable time-lapse data processing.Based on the acquisition parameter analysis of two seismic data,the authors have solved the static correction problem caused by the absence of measured elevation in old seismic data.Joint tomographic inversion of the two time-lapse data is used to obtain an uniform near surface model.As a result,the application of calculated statics removes the time shift of the two data effectively,which has laid a good foundation for the subsequent processing.

In the light of the processing requirements of the high-density wide-azimuth 3D3C seismic data and in consideration of the difference between the signal and the noise in such aspects as type,time,frequency,data field,processing step and surface area,the authors chose the means of multi-domain step-by-step de-noising.Under the prerequisite of not damaging the effective signal,the cross arranged cone wave filter was adopted first to remove surface wave and linear noise,then the low-frequency noise compilation was employed to remove residual surface wave and low-frequency noise,followed by frequency division de-noising for removing various kinds of random noise.At last,the refraction wave was removed.The monitoring display of single shot record and stacking profile has proved the effectiveness of this method and the improvement of the signal-to-noise ratio.

Log tends to be influenced where borehole environmental condition is unfavorable.The uneven wall of a well,the intrusive mud and mud cake are likely to cause the curve distortion in the depth of well diameter expansion.Density and acoustic curves are most likely to be distorted because their geodesic depth is very shallow.In this paper,the numerical value of the distorted curves was corrected to real measurement range with the multiple regression analysis method and the internal relationship between curves.The correlation between the synthetic seismic record based on the corrected curves and the seismic record near the well was relatively high,and the test results were satisfactory.This method is efficient and easily operable.It offers the high quality data for the calibration between the well and seism.

In the detection of the mined-out area in a coal mine of western Linfen, the author used the PROTEM67D transient electromagnetic exploration system, selected suitable work facilities and, through scientific experiment, determined the appropriate work parameters. According to an analysis of the transient electromagnetic electric characteristics of the local known mined-out area, the interpretation method was established for the apparent resistivity variation range suitable for the division of the mined-out area, the analysis and interpretation of the electric character sectional drawing for the whole exploration area were conducted and, on such a basis, the limits of the mined-out area and the mined-out waterlogged area were delineated. It is proved that the geological effects are satisfactory.

The high-speed railway tunnel lining always suffers from some adverse conditions, such as thickness lack, cavity, and unreasonable reinforcement arrangement. In this paper, simulation of the typical adverse lining condition was introduced by using the simulation software GPRMax2D based on finite-different time-domain method (FDTD), and the forward simulation radar images of the typical adverse lining condition were obtained. In combination with the typical radar images from detection examples of a high-speed railway tunnel, a comparative analysis was made between them, the features and rules of the adverse lining condition were summarized, the ground-penetrating radar data feature library was improved, and the credibility of recognizing typical adverse conditions of high-speed railway tunnel was increased. These results provide the effective basis for the high-speed railway tunnel non-destructive testing.