the Laowan gold deposit is an important large-size tectonic altered rock type gold deposit discovered in recent years. There exist certain differences between gold orebodies (or ore vein groups), ore-controlling structures, magmatic rocks, ore-hosting strata, near-ore hydrothermal altered zones and surrounding geological bodies, which result in obvious geophysical anomalies that constitute important geophysical prospecting indicators for gold deposits. Based on the study of geophysical characteristics of the ore deposit, the authors have tentatively summed up geophysical prospecting indicators and determined the association and flow chart of geophysical prospecting techniques so as to serve and guide the current reconnaissance and prospecting work in the gold-silver ore-forming belt on the northern slope of the Tongbai-Dabie Mountains.

Lithology reservoirs play more and more roles with the developments of the degree and the technology of the exploration in oil exploration. Thus, The new 3D seismic methods in reservoirs description are particularly needed. Attributes analyses and reservoir prediction method, and log constrained inversion method make up a perfect and available technology series. By means of this technology,some of districts such as Xin154, Wang541, Niu871 are found. Examples with the application of seismic methods demonstrate the successful possibility of exploration.

During its migration towards the surface in the forms of microbubble, water power, diffusion and filtration, the effects and styles of hydrocarbon are closely related to such geological factors as the cover of the oil and gas accumulation, fault and fissure system, nature of fluids in the reservoir and pressure of the strata. Based on an integrated analysis of geochemical and geological data from the surface and the boreholes of the Yakela gas condensate field in Tarim basin, the authors hold that there exist fine internal relations between borehole vertical geochemical characteristics of this gas field, geological factors controlling vertical percolation of hydrocarbon and surface geochemical anomalies.

Fluorescence spectroscopy of aromatic hydrocarbons in oil and gas samples has been studied. The contours and three dimensional fluorescence spectra of crude oil are obviously different from those of coal in distribution and composition of aromatic hydrocarbons. The light crude oil might obtain the features of coal if it lies in the atmosphere for several years. When rocks stemmed from terrestrial oils, there exists the peak of perylene in Constant -Wavelength Synchronous Fluorescence Spectroscopy (CWSLS); when rocks stemmed from marine oils, there is only the peak of benzene and naphthalene. Interfering factors in borehole can be recognized by fluorescence spectra. Constant-Energy Synchronous Fluorescence Spectroscopy(CESLS), a technique which involves the simultaneous scanning of both monochromators with a constant energy difference, was used to analyze the three-component aromatic hydrocarbon mixtures and the crude oil. More benefits over CWSLS were observed in both cases.

Based on the successful connection of HP1093 high efficiency liquid phase chromatograph with LS50 fluorescence spectrophotometer,the authors established a set of high efficiency liquid phase chromatographic analytical techniques for analyzing aromatic hydrocarbon components in oil and gas geochemical samples,thus greatly raising the selectivity and sensitivity of the test means.This set of techniques can not only solve the problem of qualitative and quantitative determination of aromatic hydrocarbon components but also improve the accuracy of oil and gas prognosis. What is more,it can play an important role in such aspects of organic geochemical researches as oil-oil comparison,oil-source comparison and characteristics of oil and gas migration.

Based on regional geochemical characteristics as well as features of geochemical anomalies and result of anomaly appraisal in Hanggin Qi area, in combination with geological settings, the authors carried out oil and gas prospective evaluation in this area, which led to the discovery of relatively good natural gas prospects and delineation of a favorable natural gas accumulation zone, thus providing reliable geochemical grounds for further natural gas exploration in this area.

Fuzzy synthetic judgement was conducted for 20 geological anomalies delineated by 1:50 000 soil survey in the middle and upper reaches of the Yuanjiang River, Yunnan Province. The correct evaluation rate is 100% for Rank-A anomalies. Besides, the inspection of some anomalies with relatively high synthetic evaluation values has led to the discovery of ore deposits (occurrences) of different sizes. It is shown that this method provides a relatively reliable technique for the sieving and appraisal of anomalies in the study area.

This paper deals with such conclusive remarks on the Wucun micro-and fine-rained gold deposit as the geochemical anomalies,the relationship between anomalies to alteration and mineralization,the anomaly model and the effectiveness of the ore-prospecting work.

Based on the application of bedrock survey to the geochemical reconnaissance in Shitai-Jiuhuashan area, Anhui Province, this paper points out that bedrock survey can provide abundant information for mineral exploration and remarkably raise working efficiency.

On the basis of the P-S wave reflection coefficient equation given by Aki & Richards for weak contrast media, a new approximation formula for the small incident angle is presented. For the purpose of formulating the new equation, binomial expansion is applied to the factors related to incident and transmission angles, and the sine of the incident angle is replaced by incident angle directly. Thanks to its simple form and few elastic parameters, the new equation can be easily employed to the parameter inversion. Calculation results on different models show that it is equivalent to the original equation by Aki & Richards when the incident angle is small and can make some improvement when the angle is somewhat larger. In addition, the first order approximation form can invert the shear wave impedance.

From the basic principle of seismic exploration, this paper analyzes the essence of applying seismic inversion after stack to the solution of geological problems. In the light of such aspects as the quality of basic data, the selection of techniques for logging constrained seismic inversion and the choice of inversion parameters, the setting up of the stratigraphic framework model and the extrapolation control, the paper also deals with factors affecting geological effects of logging constrained seismic inversion. It is held that the capability of logging constrained seismic inversion to solve geological problems is rather limited. Some measures are put forward for improving geological effects of logging constrained seismic inversion.

On the basis of coherence algorithms, a new method, i.e., coherence algorithms of eigenstructure-based seismic multi-vector attributes, is studied in this paper. With this method, we can overcome the defect of insufficient information obtained from the singular attribute technique. The multi-vector attributes can be fully used without any contradiction between them. In addition, the geological boundary can be well distinguished. An analysis of the practical data shows that the result is very satisfactory.

This paper describes a new spectrum stabilization method and the spectrum stabilization circuit in portable γ-ray spectrometer based on a non-volatile IC. The principle of the spectrum stabilization circuit is analyzed, and the application of the X9119 non-volatile IC is briefly discussed. The new hardware and software designing of spectrum stabilization circuit is also given in detail.

Regarded as a random signal, Potential Field can be processed by two-dimensional autocorrelation method. In this way, some objective tectonic information can be effectively acquired. The two-dimensional autocorrelation method can overcome some subjective factors of horizontal directional derivatives(0°,45°,90°,135°). In addition, the result from the analytical method is clear and straightforward, and the strikes of some boundary faults can be clearly defined. The shortcoming of the method is that some information of the data window margin may be lost. Nevertheless, this problem can be easily solved, for example, by sliding analytical windows or by adding grid data to windows. The application of this method to northwestern Ordos Basin on the basis of aeromagnetic anomalous data shows that some boundary faults, such as Helanshan fault, Langshan-Bayanwulashan fault, Zuozishan-Hengshanbao fault and Xiaosongshan fault, can be directly detected. It is also found that Helanshan fault is not very deep.

The signal/noise ratio weighted stack method by dividing frequency band is described in this paper. Weighted factors are given according to quantitatively-calculated signal/noise ratios. This method can effectively improve signal/noise ratios of stacked section without causing much damage to seismic resolution. Quite good effects have been made in real data processing.

This paper studies signal acquisition and processing techniques in the transient electromagnetic method. The densely-and uniformly-distributed original data are sampled at the interval of approximative logarithm (about 1.2 times of equal logarithm). By means of geometrical average in sampling window, the SNR (Signal-to-Noise Ratio) is improved.

On the basis of comparative analysis, the authors have advanced in this paper the integral frame and functions of the Windows-based aerogeophysical software system, and dealt emphatically with such aspects in the development of large-scale professional softwares as the standard establishment, the document compilation, and the software testing.

During the construction of the Qinghai-Tibet Railway, the perpetually frozen ground constitutes a key problem. The geophysical exploration will meet more complex and changeable objects in the perpetually frozen ground area than in the non-frozen area. Hence, the selection of rational working methods seems to be especially important. Based on a discussion on the strong and weak points of various currently-used geophysical techniques, the author advances the idea of integrated geophysical exploration with the enumeration of some practical examples. Practice shows that the integrated geophysical exploration is an effective means in the exploration of perpetually frozen ground.

The effects of applying the Diploe-Dipole Array to exploring karst cavities in the railway subgrade are demonstrated in this paper. The theoretical calculations and the model experiments as well as examples given all prove that the anomaly amplitudes are high and the interpretation is precise. The selection principles of pole pitch are also suggested in this paper.

The generality and flexibility of the mathematical-physical model and its analytical solution of the sonic echo testing forward problem are briefly discussed. According to the analytical solution, the variations of the theoretical curves of disconnected piles with the depth are calculated, explained and confirmed by examples. It is thus held that the analytical solution is universally applicable and has the advantage of numerical solution when the fitting inversion method is applied to the interpretation of practical data.

According to theoretical calculations, scale modeling experiments and actual application, the abnormal characteristics in using resistivity method to detect the high resistance pipes are analyzed. The abnormal characteristics of the cross section when the resistivity profile is not perpendicular to pipe trend are described and the related computational results are given in this paper. Some problems that deserve attention in practical work are pointed out.