The inspection of the aeromagnetic anomalies in eastern Hebei Province shows that the magnetic survey data are very effective in search for magnetite deposits at relatively shallow depth; nevertheless, these data have obvious limitations when they are used to deduce attitude and buried depth of an ore body according to the magnetism because of the error of reduction to the pole and the weathering crust. So the gravity exploration technique can play an important role in the iron ore exploration. The correct utilization of gravity-magnetic comprehensive methods can yield satisfactory ore-prospecting results in the work of iron ore exploration.

Using 1∶50 000 high precision aeromagnetic data in combination with metallogenic geological background and structural characteristics, the authors analyzed aeromagnetic anomaly features, divided metallogenic belts of Qimantag area according to the distribution of known ore deposits (ore spots), screened out a group of key ore-prospecting anomalies, established the composite ore-prospecting criteria based mainly on aeromagnetic anomaly information and, on such a basis, delineated quite a few polymetallic prospective segments. The results obtained provide important basis for further deployment of mineral exploration and also offer valuable ore-prospecting clues to surface ore-prospecting work.

This paper analyzed the feasibility of applying seismic facies technology to forecasting coal-bed methane content. The authors first made seismic wave division in the study area by using unsupervised vector quantization network, and then completed coal-bed methane content prediction in the exploration area based on seismic facies under the guidance of the measured coal-bed methane values in drill holes and according to seismic wave characteristics. The results are consistent with the measured values and have relatively high prediction of resolution, suggesting that the application of seismic facies technology is an effective approach to predicting coal-bed methane content.

Through the processing, analyzing and studying of the MT data collected in three years from the northern part of Nanpanjiang area, a method for lithofacies division and its principles were summarized based on the electric distribution in combination with the research results of sequence stratigraphy. In addition, three main lithofacies zones were delineated, which have been verified by subsequent drilling results.

The hydrothermal type Pb-Zn-Cu deposits are closely related to the volcanic apparatus in Derbur area of Inner Mongolia. The authors found and delineated a classic and relatively large-size volcanic apparatus by studying the 1∶50 000 high-precision aero-geophysical data. It is thought that the prospecting potential of this area is promising, as evidenced by analyzing and studying all kinds of data(such as aeromagnetic data, remote sensing and geological data). The result obtained can guide the ground prospecting work and speed up the mineral resources exploitation work.

The Wunugetushan porphyry Cu (Mo) deposit is a typical porphyry Cu (Mo) deposit in the Ergun metallogenic belt. Based on the depletion and enrichment regularity of 47 elements and the alteration zone or mineralization characteristics, this paper has summarized geochemical indicators of this ore deposit. The metallogenic environment indicators such as [K_K(SiO₂)+K_K(K₂O)]/K_K(Al₂O₃)+K_K(Na₂O)+K_K(CaO)+K_K(Fe₂O₃)+K_K(MgO)]、K_K(K₂O)/K_K(Na₂O),K_K(K₂O)/K_K(Rb), CaO, MgO and Na₂O can reflect the ore-forming environment and the alteration extent and delineate the alteration area. Cu, Mo, Ge, W, Sn, F, Bi, S, Se and Hf serve as the near-ore indicators, which can reflect the mineralization degree and even indicate the location of the ore body in this ore deposit; [K_K(Pb)·K_K(Zn)×1000]/[K_K(Cu)·K_K(Mo)],[K_K(As)·K_K(Sb)·K_K(Bi)]/[K_K(Cu)·K_K(Mo)],[K_K(Au)·K_K(Ag)]/[K_K(Cu)·K_K(Mo),As, Au, Ag and Te serve as the ore periphery indicators, which can enlarge the target of geochemical exploration. These geochemical exploration indicators could offer technical assistance to the prospecting for similar ore deposits in this area and broaden the geological exploration thinking for other types of ore deposits. The anomaly upper/lower limits of these geochemical exploration indicators can be determined by log cumulative frequency scatter diagram.

Based on the geological structure and the aero-geophysical features of the Da Hinggan Mountains,the authors interpreted the aeromagnetic data and, on such a basis, discovered the linear-circular structure and the volcanic rock basement. The relationships between the linear-circular structure,intrusive rock,Permian strata and gravity-magnetic features of polymetallic ore deposits were summarized. The work aims at providing references for polymetallic mineral exploration in this area.

The method discussed in this paper can replace part of the drilling work. Shallow geological conditions of the mountain areas in southern China are complex. In order to obtain high-quality seismic data, the authors have adopted the high density resistivity method. This method takes micrologging and shallow geological survey as the basis for comprehensive interpretation of high-density resistivity data so as to identify the distribution features of surface structures and low velocity layers, guide the well depth design and provide evidence for obtaining qualified seismic data processing.

With 1∶200 000 stream sediment survey data of Longguan area in Hebei Province as an example and by using trend surface analysis, the authors employed different orders of polynomial to fit the overall distribution trend of geochemical elements, recognized local anomalies and drew the anomaly distribution map. Based on a comparison with the traditional average method, this paper evaluated the application results of the trend surface method for Pb, Zn, Ag, Au and Cu, thus providing reference for geochemical work in similar areas.

In order to tackle the problem of complex overburden formation, R. Calvert and A Bakulin of Shell developed the virtual source method, which can solve the problem of building accurate velocity model. In this paper, the authors have dealt with the principle of virtual source, made a comparison with the crosswell seismic technology, and described its application in such aspects as time-lapse monitoring, imaging and virtual-shear wave. The results can provide some guidance for the understanding of this method.

Based on magnetotelluric data of Luzong area of Anhui Province, the authors studied the effects of various interference noises on magnetotelluric sounding data, made frequency spectrum analysis of several noise interference signals, and presented time series characteristics of relevant interference signals as well as apparent resistivity-phase curves. This paper has clarified the fact that noise interference that affects magnetotelluric sounding data can be divided into field source noise, geological noise and other interference noises caused by instabilities of outer factors and the observation system, which are derived from different sources. The results obtained by the authors show that the geological noise generally affects the whole frequency domain, the near-field interference mainly affects limited frequency of the high frequency, and the instability of the large power electric system mainly affects low frequency. Some suggestions are put forward in this paper for eliminating or reducing various kinds of noise interference.

Through the establishment of the model for groundwater seepage-electric test, mine roof water-inrush was simulated and coarse-grained sand, medium-grained sand and fine-grained sand were partly used as aquifer media. The properties of transient response of parameters of the geoelectric field are real time monitored by network parallel electrical equipment. Through analyzing the variation curves of spontaneous potential, exciting voltage and exciting current with time and the pictures of apparent resistivity with time, the authors have found that the experiments on three different kinds of aquifer media show apparent response and basically have the same regularity. In the process of water-inrush, the spontaneous potential of coarse sand and medium sand are significantly lower than that of the two stages before and after water-inrush. The spontaneous potential of fine sand keeps growing and shows significant changes in the water-inrush point. And the exciting voltage and exciting current keep the same changes. Compared with the stages before and after water-inrush, the exciting voltage shows great reduction and the exciting current shows dramatic rise. The apparent resistivity section diagram can clearly show the change process at seepage, water-inrush and post-water-inrush stages, which can be applied to judge the water capacity of aquifer. The study is of practical significance for the study of mine flood forecast and prevention.

Stochastic modeling and stochastic inversion are two commonly used reservoir prediction methods, and variogram is the core technology of stochastic simulation and stochastic inversion. With SⅢ Formation of North-North second block in the Lamadian Oilfield as the study object, the authors made a comparative analysis of the stochastic simulation and stochastic inversion on different variograms of 300 m×300 m, 600 m×600 m, 800 m×800 m and 1 200 m×1 200 m, so as to probe into the effects of ranges of different variables on prediction results. The results show that, with the increasing range, the stochastic simulation results vary from the sand body to a continuous sheet of discrete distribution, and stochastic inversion sand distribution are consistent with the overall trend, with only a thin layer of sand being affected in an insignificant degree. Blind shaft verification shows that stochastic inversion has higher consistency between predicted sand bodies and well points than stochastic simulation. An analysis reveals that relative to stochastic simulation, stochastic inversion is subjected to seismic constraints, thus reducing the uncertainty of sand distribution and multiple solutions and improving the prediction precision of inter-well sand bodies. Therefore, it deserves extension and application at the oilfield development stage.

In recent years, with continuous increase of high resolution seismic data, seismic stratigraphy has been more and more closely connected with high-resolution sequence stratigraphy. According to the theory of sequence stratigraphy, the seismic data should firstly be reprocessed and reconstructed to build the isochronous stratigraphy framework in this kind of application. After building this isochronous seismic volume, all seismic sequence identification, seismic facies analysis and reservoir characterization should be carried out under this isochronous stratigraphic framework. The results of the study have proved that the approaches are valid and can achieve ideal results.

The application of the triangular plane fitting method to gravity terrain correction is described in this paper. By interpolating DEM model data(or powdery point model data)of topographic map and using the triangular plane fitting method, node elevation data of terrain correction measuring board model can be obtained, with which the computerized operation is realized in terrain correction.

The technique of SPME-GC/MS has been established, which can conduct accurately qualitative and quantitative analysis of C₅~C₁₅ hydrocarbons with SPME devices designed by American Supelco Corporation and hydrocarbons standard sample. The authors made a comparative analysis of the SPME-GC/MS technique and headspace in Nanyang depression of Henan, and the results show that oil-gas implications of headspace-methane and SPME indicators are accordant with each other. The test results of surface water and oilfield water in Sichuan basin show that oil and gas properties of the drill hole can be more accurately determined by the SPME-GC/MS spectral features of oilfield water. During the oil-gas geochemical exploration work in the Xifeng oilfield of Ordos basin, the authors found that the anomaly area of total C₅~C₁₅ hydrocarbons in SPME technique is coincident with the Chang 8 main oil and gas reservoirs.

This paper reports a method for inversing interval velocity layer by layer according to VSP data, whose main feature is that the path of spread rays will be divided into linear transmission and refraction transmission, and then the interval velocity is inversed from top to bottom with VSP data. 5 layers level medium model is designed on the basis of matlab, and then the ray tracing method is used to synthesize VSP records for three kinds of well-source distance (300 m, 1500 m, 3000 m). A comparison of the inversion results of the two methods with model data shows that the linear method is applicable to the small well-source distance, and refraction method is applicable to all kinds of well-source distance. In addition, the running time of the refraction method is longer than that of the linear method, but the refraction method could only be weakly influenced by the error of first arrive, and its capability against interference is strong.

It is usually considered that TEM detection which uses the signal of secondary induction field is influenced little by the topography. Based on many years' production practice, however, the authors have found that the influence of topography should not be neglected. Due to the relatively shallow burial of the coal seam, TEM detection in the coal field is influenced considerably by the topography. Using the commonly used depth calculation formula in the coal field, the authors calculated the influence extent of topographic variation on induced electromotive force and on attenuation time separately. Then, the two influencing factors substituted for parameters so as to recalculate the apparent resistivity. According to the new apparent resistivity calculation depth, a set of practical topographic correction methods for the coal measure strata could be obtained. Lastly, by designing the corresponding software, the comparative profiles before and after correction can be displayed in real-time. The theoretical model and actual data have proved the effectiveness of this method and the software.

Determination and calculation of magnetic parameters of rocks and minerals are faced with some problems such as ambiguous location determination, incorrect units of T₀, ID confusion of specimen surface and negative magnetic susceptibility. On the basis of previous studies and starting with determination of Gauss position using mechanical magnetometer and formula derivation, this paper first analyzed the difference in principles between proton-type magnetometer and mechanical magnetometer, and then clearly explained Gauss first position, Gauss second position, the number of specimens surface, the order determination and unit of geomagnetic field. The cause of negative magnetic values were also analyzed and the measures for improvement were put forward. The results obtained can be of some help to the determination and calculation of magnetic parameters of rocks and minerals.

This paper describes the basic principles of DDS (Direct Digital Frequency Synthesis), and puts forward a hardware design of the mixer used in Electromagnetic Wave Resistivity Tool based on DDS chip. Psipce simulation shows that the system has good reliability and precision.

The EM field of arbitrary shape loop can be regarded as EM field with the summation of many horizontal electric dipoles; therefore, as long as we work out the horizontal electric dipoles of the EM field and add them up, we can get the EM field of the arbitrary shape loop. The key of this method is the division of electric dipoles in arbitrary shape loop. In this paper, according to distance from the measuring point to the line of loop, each line of loop is divided into many small pieces with each piece satisfying the condition of horizontal electric dipole, and then numerical integration of horizontal electric dipole is carried out. In this way, the EM field of the whole loop can be obtained. Tests show that this method can not only reduce calculation amount but also improve calculation precision.

A novel model of digital Gaussian filtering is presented in this paper based on Sallen-Key filter. Depending on a second-order differential equation, the authors obtained a general numerical recursive root between the input and the output by applying numerical differentiation algorithm, and implemented digital Gaussian filtering of nuclear pulse signal as well. The operator of the model is confirmed by standard index signal and actual measurement signal simulation.

Using the foam trap and liquid trap, the authors carried out large-scale geogas survey in the Jinwozi V210 concealed gold deposit located in the boundary between Hami of Xinjiang and Anxi of Gansu, and studied the field application of the geogas survey method. The results indicate that Au geochemical anomalies are quite clear over the ore deposit and are associated with some other anomalies such as Cu, Pb and Fe. The anomalies found at the surface are related to the depth and attitude of the ore body and the structures. The REE patterns of the trace elements collected in the process of this survey are similar to patterns of the trace elements collected from the ore body, suggesting that the trace elements over the gold deposit were derived from the buried ore body. This study shows that the deep-penetrating geochemical method for concealed ore deposit prospecting in gobi area has promising future.

Shouguang was once the key area of preventing endemic fluorine disease in Shandong Province. Based on field survey and soil and water sample test, this paper summarizes the distribution of fluorine disease area and geochemical environment characteristics and studies the relationship between fluorine disease and geochemical environments such as lithologic character, soil, terrain, shallow groundwater and water for human living. On the basis of systematic environment geochemical survey, the cause of high-fluorine groundwater was studied. It is considered that rock, soil and seawater constitute the main sources of high-fluorine groundwater. There probably exist two patterns for the formation of high-fluorine shallow groundwater, seawater invasion enrichment and evaporation concentration. The factors and processes of fluorine enrichment in groundwater are studied and the preventing measures are proposed.

Multi-purpose geochemical survey in the Hongfeng Lake of Guiyang City shows that its pH values are between 7.3 and 7.5 suggesting an intermediate and somewhat alkaline environment. Lacustrine sediments are characterized by entrophication, high concentration and enrichment of C, Corg, N, S F and P and hidden dangers of heavy metals such as As, Cd and Hg. The concentration of As is between (34.6~52)×10^-6, 40.8×10^-6 on average, exceeding the Grade III of Environmental Quality Standard for Soils. According to year-round monitoring and monthly sampling, the pH values of lake water are between 7.5 and 8.0, also implying an intermediate and somewhat alkaline environment, and the total N exceeds Environmental Quality Standards for Surface Water. The authors consider that the water quality of the lake may be impacted by geochemistry of lake sediments, and hence put forward some proposals for eco-environmental protection of important water source sites in Guiyang City on the basis of a comprehensive study of sediments and water in the lake.

Geochemical characteristics of 29 elements or indicators which had been analyzed and tested were studied in this paper on the basis of the shallow groundwater data obtained from the agro-ecological geochemical survey in eastern Shandong Province. the results show that several indicators (such as Mo, Pb, Mn, Fe, Cl^-, NO₂^- and total hardness) in the shallow groundwater of the study area have changed significantly, which has led to the deterioration of local groundwater quality. Other indicators have changed relatively insignificantly and are evenly distributed in the shallow groundwater. In the light of the Quality Standard for Groundwater and Standards for Drinking Water Quality, the authors made single factor and integrated environmental quality evaluation of local shallow groundwater. The results show that the area of shallow groundwater unsuitable for direct drinking accounts for 44.88%, the integrated environmental quality is relatively poor, groundwater pollution occurs in such areas as major cities, industrial and mining enterprises as well as their surrounding districts. Single indicator groundwater pollution assumes point-like or linear distribution, the exceesive indicators include total hardness, total dissolved solids, potassium permanganate index, NO₂^-, Cl^-, F^-, Mn, Fe etc. The studies were focused on the formation mechanism of high-density fluorosis in shallow groundwater, and the result provides a basis for prevention and treatment of fluorosis in the study area.

At present, the small coal mines have exploited lots of water areas and brought great harm to the safety production of coal mines. We must detect them effectively and timely so as to make appropriate measures and ensure safety production in coal mines. The adoption of the effective exploration methods and the detection of the spatial features of hydrogeological calamity are very important for controlling hydrogeological disaster. In this paper, the principle of the transient electromagnetic method (TEM) was formulated and the single loop setting of TEM was selected. With some engineering examples in some coal mines as examples,the features of the geophysical anomaly of the mined water areas were analyzed,and the effect of the method in detecting the mined water areas was discussed. The results indicate that this method have some advantages such as high resolution,low cost,fastness and accuracy in hydrogeological calamity investigation. It can meet the safety production of the coal mine.

Tilt-angle derivatives method requires no source property and structural index and can quickly estimate magnetic source boundary location and depth distribution, thus having good prospect in rapid interpretation of large-area magnetic anomalies. In this paper, the authors present some algorithm improvements based on Salem's tilt-angle derivatives method. Finite difference method is used in space domain to convert horizontal derivatives of magnetic anomalies, and ISVD algorithm is employed to convert high-level vertical derivatives of magnetic anomalies. A method is also presented which combines the filtering generalized tilt-angle total horizontal derivatives of magnetic anomalies with screening the effectiveness of source depth to remove bad solutions. Theoretical model test shows that this method is simple and quick, and hence its effect is obvious.

This paper deals with optimizing algorithms of lithologic modeling. Firstly, under the guidance of high resolution sequence stratigraphy, geological, outcrop, seismic, logging and other static data are applied to the fullest possible extent. The logging data advantage of high vertical resolution and the seismic data advantage of rich lateral information are exploited to the full to establish the high accuracy isochronous stratigraphic model under the restraint of geological regularity. Then, taking the petrographic data obtained from well log data as the condition data, and using indicator kriging algorithm, truncated Gaussian simulation,object-based simulation and sequential indicator simulation, we can establish the sand body distribution model. Lastly, algorithms are optimized through sampling inspection so as to establish three-dimensional high-precision geological model under the conditions of different well densities and different development stages. It may contribute to establishing 3D geological model in some oilfields with similar geological backgrounds. A comparison shows that the optimized indicator kriging and sequential indicator simulation can better characterize geological features of the target area.

This paper proposes a new type of DC advanced detection device, which is named the "U"-shaped DC advanced detection equipment, with the purpose of improving the accuracy of the DC advanced detection and better eliminating or weakening the impact of non-ahead geological faults. The authors used the computer to simulate the prospecting process by using the "U"-shaped device and compared the result with that of the traditional DC advanced detecting device. The expected conclusions were reached. As the desired effect was obtained, the authors also carried out the flume experiments using the "U"-shaped device. A series of experimental data and simulations have led the authors to believe that the "U"-shaped DC advanced detection devices is efficient in detecting geological faults in a certain degree.

The high precision magnetic survey is liable to suffering many kinds of surface interference which cause data distortion; therefore, the distortion points must be rejected before processing. For the purpose of implementing interactive rejection of distortion points in magnetic data, the authors employed the functions of Matlab GUI, which are characterized by visualization, drawing and mouse case. In practical application, this method enhances the efficiency of rejecting distortion points in magnetic data and preserves most information of normal data points.

The image of ultrasonic televiewer logging often has a lot of abnormal points, and hence this paper proposes a new method for reducing outliers based on the TV-inpainting to solve the problem of extracting these outliers. Firstly, it chooses reduced outliers according to the threshold in the selected regions, and then utilizes TV-inpainting to repair these outliers. The processing results show that the proposed method can effectively extract the outliers, ensure logging image integrity, and significantly improve image quality, which is of very important practical significance for processing the logging data.

The electrical information obtained by 3D collection and 3D inversion is stereoscopic. The best way to show electrical results is displaying 3D body of data stereoscopically, rapidly and efficiently. In this paper, in combination with the characteristics of electrical data, the authors realized 3D visual presentation of electrical data by using graphic user interface (GUI) on the Matlab platform. The program can be used to study the characteristics of 3D electrical results and is also of reference value for visualization of other geophysical data.

Noise attenuation plays a very important role in seismic data processing, and signal-to-noise ratio of seismic data will directly affect the subsequent data processing result. In the light of the character of the coherence interference in the seismic record and by using the frequency decomposing technology of the wavelet transform, the authors use the radial trace median filtering to separate the coherence interference from the common frequency band of the coherence interferences and signals. The coherence interference is reconstructed by reverse wavelet transform and deducted from original data, and consequently high-fidelity de-noise is achieved. Real data processing demonstrates that this method can effectively improve quality of the seismic record and enhance the signal-to-noise ratio of the seismic data.

This paper describes the basic principle of Equivalent Offset Migration and Non-imaging Shot-record Migration. They both replace the usual offset coordinate with a new offset variable. The result of prestack time migration is followed by NMO and stack over the hyperbolic traveltime curve defined by the new offset variable. It is realized that prestack time migration is diffraction summation over the traveltime surface described by the double square root equation. The difference between the two methods is that they define different summation paths over the traveltime surface.The two methods can used to seismic imaging in the metal ores exploration.