Low density geochemical survey in Yishenjilike mountain area led to the discovery of a huge gold geochemical block, and the verification and evaluation of gold anomalies led to the discovery of the Bogutu gold deposit. In combination with the geological characteristics of the prospecting area, the authors carried out a series of geological-geophysical-geochemical exploration work, delineated quite a few geochemical and IP anomalies, and detected the characteristics of ore-bearing structural belt. Through trenching and drilling verification, the authors found more than 40 gold orebodies, thus achieving good ore-prospecting results.

The Yazigou copper-polymetallic deposit is located in Yaziggou area, Mangya Town, Qinghai Province. The development of granodiorite and Tanjianshan Group carbonatite in the area constitutes the main ore-controlling factors to form skarn type copper-polymetallic orebodies. Based on regional geologucal, geophysical and geochemical features, the authors employed the IP intermediate gradient method and the ground high-precision magnetic comprehensive geophysical prospecting method in search for ore deposits in the predicted metallogenic prospect areas. IP intermediate gradient method was used to delineate IP body anomaly, and ground high-precision magnetic measurement was adopted to detect the magnetic features of main geological bodies in the area. Along the important geological sections, IP sounding was used to guide drilling work. Practice indicates that this method is very effective and efficient, and has the reference value for exploration of concealed polymetallic deposits in similar metallogenic regions.

The reservoir of Triassic Baikouquan Formation on Mahu slope in Junggar Basin is characterized by low porosity,low permeability,and thin tight conglomerate,with only the subaqueous grayish green conglomerate with medium porosity being the high-quality reservoir. Because central frequency of seismic data is low (25~30 Hz),the thickness of the thin layer is about 10 m,and the impedances of high-quality reservoir and tight layers are overlapped in these reservoirs,the commonly used post-stack impedance inversion and pre-stack simultaneous inversion are not very effective in prediction of high-quality and thin reservoirs.In this paper,based on core,logging and test data,the authors carried out the petrophysical analysis and established the petrophysical chart by using P-impedance and v_p/v_s,and then identified the parameter of the effective reservoir of this area.Finally,the authors conducted the pre-stack geo-statistic inversion that combines the advantages of the simultaneous inversion and geo-statistics inversion,and predicted the high-quality and thin conglomerate reservoir.The result of inversion indicates that the pre-stack geo-statistics inversion can effectively identify the high-quality and thin conglomerate reservoir and provide reliable basis for further exploration and development.

The study of the geochemical characteristics of Taxiu-Qushi'an area was based on the 1:50 000 stream sediment survey. The authors obtained plentiful regional geochemical survey data. Through mathematical statistics and concentration distribution, the authors carried out mathematical analysis of 17 elements and also discussed spatial distribution and composition relationship of elements by cluster and factor analysis. According to abnormal distribution and elements mineralization characteristics, the authors chose 4 mineralization prospective areas through optimization and, on such a basis, suggested that the Maridang-Aerganlongwa prospective area is the favorable area in search for W and Au, and the Muyanggou-Tuotougang prospective area is the favorable area in search for Au.

The application effects of AMT in the exploration of shale gas target layer in the black silk shale of Xiuwu basin are described in this paper. The resistivity section obtained by AMT was divided into 5 layers from the deep part to the shallow part, the AMT explored the development characteristics of the stratigraphic structure and faulted structure of the Luodong syncline. The AMT also explored the buried depth, thickness and distribution characteristics of the black silk shale targets on the basis of the low resistance of the black silk shale relative to surrounding rocks. The buried depth of shale gas targets in Luodong synclinal core is about 1 000 m, and the thickness of the target layer is 160~200 m. The exploration results by AMT provide an important basis for the prognosis and evaluation of shale gas and the well deployment for shale gas exploration in Xiuwu basin.

The primary halo characteristics of eleven kinds of trace elements (Au, Ag, Cu, Pb, Zn, W, Mo, Hg, As, Sb, Bi) in K6 orebody of the Longmendian silver deposit were studied in order to provide theoretical basis for deep orebody prediction. Pb, Zn can be used as the important indicator elements in the prediction of K4 deep orebody, and ore-forming process has superimposed metallogenic features, as shown by the results of statistical analysis. Through the analysis of the variation law of primary halo geochemical parameters of the orebody, the authors found that the front of the orebody exhibits an obvious strong anomaly of tail halo indicator elements, whereas the center of the orebody exhibits an obvious strong anomaly of frontal halo indicator elements. Axial zoning sequence of the indicator elements is described as follows: W-Mo-Au-Hg-Cu-As-Bi-Zn-Ag-Sb-Pb, assuming obvious frontal halo and tail halo coexisting phenomena and axial zoning characteristica. It is therefore considered that there is a quite large-sized blind orebody in the depth and there is excellent mineralization under 909m level.

In this paper,a 3-D geological model for the Jiujiang-Ruichang ore concentration area was constructed by using a series of integrated geophysical interpretation profiles based on the stereoscopic geological mapping graphic system developed by MAPGIS K9 platform,and the accuracy of this 3-D model was proved through drilling verification in two different target zones of the srea.The results achieved provide more intuitive information for understanding the deep geological structure of the area and exploring the deep mineral resources prospective areas in the Jiujiang-Ruichang ore concentration area.

Zambia possesses very rich mineral resources; nevertheless, in the past work, prospecting focused only on copper, cobalt and gemstone deposits, whereas the attention to gold deposits was very insufficient. Based on 1:10 000 soil geochemical survey, the authors conducted detailed soil geochemical survey in the Shiganda ore district in Northwest Province of Zambia. Through studying element distribution characteristics, individual element anomaly features, element correlation, and multiplicative combinational anomalies of related elements, the authors determined Au and Cu as the target ore species elements in the study area, and delineated the next-step prospecting target area.

Elements anomalies, such as Ag, As, Au, Ba, Bi, Co, Cr, Cu, Fe, Hg, Mo, Mn, Ni, Pb, Sn, Sb, Ti, W, Zn, from 1:50 000 stream sediment survey, North Qilian tectonic belt, vary with the tectonic evolution in different geological epochs, the elements themselves are endowed with dual properties of time and tectonic setting. According to the contrast value method, element content data of 49 303 samples from different strata were processed in combination with stratigraphic geochemical R cluster grouping. The results show that Co, Cr, Ni anomalies are in response to Paleoproterozoic post-orogenic cracking, Au, Bi and part of Cu anomalies are in response to Ordovician oceanic subduction-closing stages, Pb, Zn anomalies probably corresponded to local volcanic activity in the ocean floor in Ordovician-Silurian period. Devonian Hg, Sb anomalies have no reasonable regional tectonic interpretation, and the phenomenon of Mo element content in the Carboniferous peak indicates strong uplift and erosion on the periphery of North Qilian orogenic belt. W, Sn element anomalies reflect subduction and collision setting in Ordovician and Silurian. The regularity of the stream sediment anomalies' response to tectonic evolution suggests that the compatible ( incompatible ) features of mantle-derived elements from stream sediment survey can better distinguish tectonic environments, and the combinational geochemical approach from a large data sample and tectonic study is feasible.

In this paper,the authors systematically analyzed and studied the geophysical field and characteristics of the basement structure of Tianjin by using gravitational,magnetic and electric data.Some conclusions have been reached:the analysis of the gravitational,magnetic and electric field could satisfactorily recover the tectonic framework of the study area,the regional geophysical field is the reflection of the Archean crystalline basement,the change of the local field has close relationship with the pre-Mesozoic folded basement,the pre-Mesozoic basement shows a characteristic of fault block combination cut by the fault,and there are magnetic volcanic rocks distributed along the huge fault.On the basis of the delineation of the master fault system,the authors divided the study area into four tectonic units:Malanyu anticline,Jizhong depression,Changxian rise and Huanghua depression;using the gravity and magnetic anomaly,the authors delineated the distribution of local structures and magnetic geological bodies.The results obtained by the authors provide basic geophysical data for the study of the regional crustal stability and the evaluation of mineral resources.

With the hydrogeological survey in a gold mine in Xinjiang as an example, the authors specifically studied and analyzed the feasibility and application effect of the technique that combines high frequency MT sounding method with dual frequency IP method. The results show that using the dual frequency IP method in the area affected by human interference can avoid the mistaken inference of the location of fault by high frequency MT sounding method, and enhance the precision of interpretation of the location of fault. The two methods make complements to each other and hence can solve the problem of water exploration in the mine affected by human interference effectively.

Stratabound copper deposits constitute the main kind of copper deposits in the copper belt province of Zambia. Copper deposits occur within sediments of Lower Roan Formation, Katanga Supergroup. Based on geological features of stratabound copper deposits, the authors studied geophysical anomalies of known orebodies in three stratabound copper deposits by using IP intermediate gradient and EH-4 electromagnetic sounding. On such a basis, the authors summarized the regularity of electrical anomaly from ore-bearing rocks and main wall rocks, and established geophysical electrical signal model for main wall rocks and ores, which can guide the prospecting for the same kind of copper deposits in the copper belt province of Zambia.

In many kinds of geochemical exploration methods such as acidolysis hydrocarbon, dissolved hydrocarbon and thermally released hydrocarbon, the geochemical pretreatment of the sample is very important. Nevertheless, China's sample retreatment technique remains at the stage of manual operation, which does not match the widely used high-precision analytical instruments. On the basis of researches on the intelligent-control geochemical sample pretreatment system, this paper deals with in detail the working mechanism, control structures, implementation methods, performance indexes and quality inspection results of this system, and describes the application achievements in gas hydrate exploration with acidolysis hydrocarbon methods in ODP204 and dissolved hydrocarbon methods in Dongsha area, the South China Sea. Practices have proved that the intelligent-control system is capable of completing the geochemical sample pretreatment work under the automatic condition, and has properties of fastness, precision, safety and portableness. It has promising application prospect in China's marine gas hydrates exploration and terrestrial petroleum geochemical exploration, and also has great significance for improving China's geochemical sample pretreatment equipment techniques.

Chinese vast territorial seas and rich inland waters constitute a long glorious history of navigation history,and have left huge underwater cultural heritages.As to underwater detection of buried ancient wooden shipwrecks,underwater archaeology is anxious to seek support from the related disciplines of technology,because the ancient wooden shipwrecks carry the dream of restoration of Chinese marine culture.In this paper,the physical model of field test and analysis of the wooden shipwrecks confirmed that the wooden shipwreck can cause the change of the surrounding magnetic field,and the authors also found out the field source material that caused the change of magnetic field.These results confirm the feasibility,reliability and validity of the magnetic method in detecting wooden shipwrecks,the application conditions for magnetic detection of wooden shipwrecks are also discussed in this paper.

Because of the severe electromagnetic interference and the human interference in a copper mine in Anhui Province, the traditional electromagnetic method is unable to obtain valid data. CSAMT method has stronger anti-interference capability, but the mean square relative error of CSAMT checkpoints data reaches 53.6% and the exploration effect is poorer. In this paper, wide field electromagnetic method was applied to the mining area and led to the obtaining of the high quality data, with the average relative mean square error being 5.6%. Compared with the inversion result of CSAMT method, wide-area electromagnetic inversion result is in accordance with the geological data, the depth error is less than 10%, and the position of the orebody is consistent with the drilling information. The test results show that wide field electromagnetic method has stronger anti-interference capability and can be used in strong interference field detection.

In consideration of the characteristics of dipole array TEM, This paper gives three-component response of thick plate models with three-dimensional forward modeling software and summarizes the characteristics of TEM curves. The calculation results show that the horizontal component can show the edge and position of the anomaly body, while the vertical component can show the center. Multi-component survey can offer more reliable information and provide more evidence for interpretation of field data.

In view of the problems and challenges in pre-stack reverse-time depth migration (RTM) for mass seismic data,the paper focuses on introducing GPU-RDMA and GPU-Stream,which are used to solve the large calculation cost and the mass memory demand of RTM on the CPU/GPU heterogeneous platform,and develops the RTM suitable for large-scale distributed parallel computing in GPU clusters.This technology can be used to deal with the high density seismic data,and the results of actual seismic data application show that the computing efficiency is up to 15~40 times.

There is mostly rough deep sea bottom topography on the northern slope of the South China Sea.All types of multiples are well-developed.Identification and suppression of multiple have always been the emphasis and difficulty in the area's seismic data processing.The selection of a suitable method from multiple attenuation techniques is the key to obtaining high quality imaging of seismic profile.Through the study of multiple in original seismic data of three lines located on the northern slope of the South China Sea from the east to the west,the authors analyzed the characteristics of various types of multiple,applied τ-p domain deconvolution prediction,SRME(Surface Related Multiple Elimination),high-precision Radon transform and frequency versus energy decay method to effectively suppress various types of multiple,thus making improvement of the quality and effects of composition and clarifying characteristics of reflected waves in the middle and deep layer.As a result,the distinction and explanation become easy.

In the light of the geological conditions of the new exploration field abroad characterized by complexity,varying water depth,scarcity and uneven distribution of drill holes,and lack of velocity data,it is often difficult for conventional methods to carry out fine time depth conversion.In order to effectively detect the structure,this paper proposes using seismic data and the available well data to build virtual wells for quantitative characterization in no-well area.The reasonable construction of virtual wells can effectively reduce the uncertainty of the velocity field's establishment,ultimately improve the time-depth conversion accuracy of the study area,and lay a solid foundation for the optimization of traps and evaluation of favorable targets,so as to reduce the risk of exploration.Using the establishment of virtual well constrained velocity field,such a means provides a feasible choice of time depth conversion in the area characterized by no or few wells,remarkable varying water depth,and drastic stratigraphic change,thus effectively improving the accuracy of time-depth conversion.

The analytical data of drill holes from the Jiama polymetallic copper deposit exhibit striped distribution. When Cokriging is used for these striped data, the outlying data in the stripe frequently receive higher weights than all other data. This paper first introduced the relevant theory of Cokriging algorithm, then corrected the weight of outlying data in the stripe based on Cokriging algorithm with the purpose of making outlying data receive smaller weights, and finally presented the program of the correction algorithm. With the grade data of Cu in the Jiama ore district obtained in 2012 as an example, the authors calculated Cokriging and Cokriging of weight correction respectively. The results show that the Cokriging of weight correction can achieve the better effect and hence it is important for the modeling of geological properties, reserves estimation and spatial data of the Jiama polymetallic copper deposit in Tibet.

Geo-electrochemical extraction is an effective method in mineral exploration for overburden covers, the principle of which is to extract near-surface materials selectively artificial electric field. The exploration method provides prospecting information by studying the electrical extracted element combination、content distribution and anomaly characteristic. Applying this technique to the Luokedun deposit in Inner Mongolia, we proved the effectiveness of geo-electrochemical exploration for aeolian shallow overburden areas. Comparing different extraction time and density carriers, we conclude that the extraction time of 24h and high-density ploolyform carrier material is the best choice for geo-electrochemical exploration in this area.

Wavelet multi-scale analysis is a useful method in gravity data processing. Its analytical result is closely related to the selection of the optimum wavelet base. In this paper, combined with the characteristics of gravity data, the authors first analyzed the selection of the optimum wavelet base theatrically, and then made a tentative comparison of different wavelet bases using the theoretical data and the gravity data obtained in North China. The research shows that db11 is the optimum wavelet base in the gravity data processing.

The buried hill of the PL9-1 oilfield is a Mesozoic granite buried hill,which is characterized by shallow buried depth,strong weathering degree and great lateral variation of fractured reservoirs.On the basis of fine rock physical analysis,the density can better recognize the fractured reservoirs in the buried hill of this oilfield.Nevertheless,in this buried hill,the density baselines between wells show differences,which leads to different density measurements in describing the reservoirs.This is a challenge to predicting fractured reservoirs between wells.This study successfully solved the problem of density baseline differences between wells by using the method of density baseline differential correction,combined with verifying the feasibility of pre-stack inversion by the forward model analysis of AVO.The corrected density volume was achieved by pre-stack inversion.Furthermore,taking advantage of the good relationship between the corrected density and total porosity of the fractured reservoirs,the authors used the corrected density volume to describe the distribution of fractured reservoirs in the buried hill and further reflect the development degree of fractured reservoir porosity horizontally.The result was proved by actual drilled wells.The successful application of this technology will provide important reference for the similar fractured reservoir studies of buried hill in future.

Seismic wavelet plays a vital role in seismic processing,the traditional wavelet extraction is based on the minimum phase wavelet in seismic data.However,the wavelet in the actual seismic data is of mixed phase.In order to obtain a more accurate wavelet,the authors used high-order bispectrum to reconstruct the seismic wavelet so as to get a more accurate wavelet,and then conducted wavelet shaping processing to improve the vertical resolution of the seismic by using the statistical wavelet.The feasibility of using high-order bispectrum to reconstruct the seismic wavelet was proved by the simulation experiment.Practice shows that the statistical wavelet has good application effect in wavelet shaping processing.

Arsenic is mostly present in rocks and arsenic ores in the form of sulfides rather than in the nature element form. Arsenic poisoning is a biogeochemical disease which poses a great threat to human health. As a result, there has been a growing emphasis on the study of arsenic poisoning. This paper is based on multi-target geochemical survey of the Hetao area and delineates the range of the arsenic poisoning in the Hetao area with a comprehensive analysis of the distribution of arsenic in different media. In addition, this paper summarizes and evaluates the geochemical distribution of arsenic in the Hetao area. Based on the analysis of arsenic content in various sources, the authors have reached the conclusion that the main source of arsenic-rich substance in the Hetao area is the Yellow River alluvial matter.

Main procedures of rapid investigation of gas station mainly include data collection, visits, field reconnaissance, geophysical prospecting and sampling. The purpose is to get a preliminary understanding of the basic situation of the gas station, risk of leakage pollution and possible point of leakage pollution. Three gas stations respectively in Shanghai, Beijing and Nanjing were selected to carry out the procedures and confirm the effectiveness. Soil gas was taken and ground penetrating radar (GPR) was used to detect pollution in the two gas stations in Shanghai and Beijing. The results show that leakage pollution did exist at the two gas stations. GPR detection in the gas station in Nanjing confirmed that pollution did not exist at the site after soil remediation.

Particle swarm optimization (PSO) is a global random search algorithm put forward by simulating the flock foraging in the process of social behavior based on swarm intelligence. Researchers have proved that PSO algorithm is an effective geophysical inversion method, and it does not rely on the initial model. Because the conventional PSO is easy to be stuck in relative extremum, slow convergence speed in the late and the inversion accuracy is not high, this paper presented an improved fully chaotic oscillations particle swarm optimization algorithm based on same conventional PSO theory. It improved the formula of updating speed, made the particles getting the difference between the current global best position quickly, enhanced the learning ability of particles. The paper did a two-dimensional numerical test on ERT data in matlab2012b programming environment,the results show that this algorithm inversion is not dependent on the initial model, increases the search space,and have higher inversion in accuracy than the standard PSO, and the image quality is better than that of Levenberg-Marquardt method.

The EM-coupling is one of the basic interference in the spectral-induced polarization, especially when the working area is covered with lower-resistivity layer or the current electrode spacing is large. It has great impact on the depth of the exploration and the effect of exploration. Recently, most methods to remove the EM-coupling are centered on the multi-frequency amplitude and the multi-frequency phase. These methods are based on the amplitude and the phase difference between the IP effect and the EM-coupling, which do not work well at strong EM-coupling. The authors' work is based on the IP model, and fits the IP effects with exponential function. Then the EM-coupling effects are removed from the time domain data. The phase and the relative phase after removing EM-coupling are confirmed more effectively based on the application in field data.

Based on the triangular mesh dissection of the finite element method, this paper presents the 2.5-D airborne transient electromagnetic method forward modeling. Firstly the time domain electromagnetic partial equations are converted into laplace domain with the numerical time-frequency transform algorithm, then the 2.5-D expressions are obtained from 3-D case by adopting the fourier transform. The airborne data are acquired from the results of the digital inverse laplace transform of the 2-D electric and magnetic components in laplacian domain, which is computed using finite element method.Instead of the conventional algorithm, the anomalous field method is employed throughout the finite element process, so that the source singularity of total field is avoided. the source impact is embodied in the differencial equation by appling the background electromagnetic field item.The computing accuracy and efficiency would be managed rigorously due to the wide dynamic range of the transient singnal, as well as the two-time inverse laplace and fourier transforms. Otherwise the accumulative error will soar acceptably. The synthetic model experiments shows that the numeric modeling solutions match the analytical results of homogeneous and layered erath responses well, which also proves the effectiveness of the algorithm.

For the reason that dual induction logging method will be affected by such factors as mud invasion and wall rocks, an improved genetic algorithm based on niche technology is proposed to perform inversion of virgin formation resistivity, invasion radius and other formation parameters. The multiple layered medium is set as model to conduct algorithm verification, The results can well reflect the formation parameters. With the actual dual induction logging data, the new interpretation drawn by the inversion of virgin formation resistivity is more close to the test data.

Quality factor (Q) is a key parameter for geophysical exploration in that it indicates the magnitude of sediment attenuation.When attenuation is large,quality factor computed by conventional methods such as spectral ratio method is smaller than 2π,which is the low limit of Q calculated by defining expression.Conversion formula for the two quality factors is introduced by investigating the differences between them.Model tests indicate that,when quality factor is lower than 30,relative error between quality factors calculated by two methods is larger than 10% so that they should be distinguished one from another.Based on this study,the authors put forward some advises.First,during Q-V fitting process,it is prefer to use the quality factors calculated by defining expression.Second,conventional method is preferred in gaining quality factors in reverse Q compensation process.Third,when the comparison of quality factors is needed in an oil field,quality factors should be converted to the same class before the comparison.

For the purpose of common mid-point bin attribute analysis from high density exploration and three-dimensional seismic geometry,this paper analyzes the calculation characteristics of bin analysis,and proposes an efficient parallel algorithm for bin attribute analysis based on Open Computing Language (OpenCL) heterogeneous programming model.The algorithm divides bin grid into several sub-regions under hardware memory constraint.Tasks of sub-regions are executed with coarse-grained parallelization by assigning task to different devices,whereas pairs of source-receiver in sub-region are executed with fine-grained parallelization.With HP's Z820 desktop workstation,experiment was carried out with high density three-dimensional geometry from seismic exploration.The experimental results show that the parallel algorithm takes full advantage of multiprocessor's parallel processing capability,and the processing speed is about 30 times faster than that on CPU-based implementation (single core) under the condition that the precision is not changed.

Gas pipeline is the basis and guarantee of urban energy delivery, and hence accurate pipeline plane position and buried depth are important information for gas company operations management and the establishment of the GIS system. In recent years, due to the advantages of anticorrosion capability, PE pipeline has been widely used in medium and low pressure town gas transmission. As PE pipe is an inert material which is non-metallic, conductive, permeable, so it's difficult to determine its position in the underground space. In this paper, the authors analyzed the detecting principle and locating method of geological radar, studied imaging characteristics of PE pipeline in geological radar and the method for distinguishing steel pipe from cable, and investigated the inflection point, tee with casing, PE pipe. In addition, a method for determining the feasibility and accuracy of detection method was verified by the excavation. The research results have important significance in improving the detecting precision of PE pipeline as well as the gas pipe network information system.

TSP detection has been one of the most important means of geological prediction. According to the practical engineering experience on TSP203, this paper discusses some problems concerning TSP data acquisition and processing, such as the adoption of delayed trigger of detonator to guarantee the synchronism of data acquisition, the reformation and adjustment of the trigger system, the adjustment of explosive quantity, the improvement of package, the adoption of band-pass filter, and the suppression of pipe wave. These application means can serve as reference for other users.

With the merits of simplicity and rapidness, the negative apparent velocity method has been used widely in tunnel geological prediction. The regular method indicates that the intersection of time-distance curves of direct wave and reflected wave is just the position of reflecting interface. However, for inclined interface, the interface position cannot be identified accurately if we only extend time-distance curves. What's more, the more lean the angle, the greater the error. This leads to serious accidents in practice because of inaccurate prediction. Aimed at solving the problem, the authors mainly studied the inclined interface, used the newest coordinates method to get time-distance curve of reflected interface, and then fitted their interpolation, mainly including polynomial fitting curve, unitary three-points isometric interpolation and interpolation by continued fractions. Through a lot of tests and comparisons of the characteristics of all interpolation fittings, the time distance curve interpolation by polynomial fitting can be worked out so as to identify the position of reflected interface accurately. Finally, interface dip (apparent dip) can be calculated using geometric formula. This method facilitates the data processing by means of negative apparent velocity.