The offshore oil and gas geochemical indices generally include hydrocarbons and their alteration products in submarine sediments as well as hydrocarbons in seawater media. The oil and gas geochemical exploration with concentrations of hydrocarbons and their alteration products as the main objects is one of the few methods for evaluating offshore oil and gas prospects. In present, bottom bed water sampling and analysis and coring analysis of submarine sediments have constituted an effective and relatively economical technical combination, and the coring measurement of submarine sediments and in-situ sniffer analysis are main means for offshore oil and gas geochemical exploration. Numerous offshore oil and gas geochemical exploration researches conducted both in China and abroad prove that offshore oil and gas geochemical exploration can provide important information for the recognition of oil-and gas-bearing prospect blocks and the judgement of oil and gas attributes in oil- and gas-bearing prospect structures.

Geological database has been widely used. In the whole geological database, geochemical database occupies an important position. Geochemical database can be classified into 6 types, namely, solid ore geochemical database, oil and gas geochemical database, isotope geochemical database, agro-ecological environmental geochemical database, geochemical analytical database and standard reference materials database. The present conditions, applications and development trends of geochemical database have been analyzed and discussed in this paper.

Based on the results of the newly-completed 1:50 000 high-precision aeromagnetic survey in northern Derbur of Inner Mongolia, the authors made a relatively detailed division of fault structures and lithologic characters in the northern part of the Derbur metallogenic belt, added or revised lots of geological data, and conducted an analysis and interpretation of newly-inferred fault structures and newly-delineated lithologic units, thus obtaining much new knowledge. It is pointed out that there exist close relationships between magmatic, altered and metamorphic rocks and Au, Ag, Cu, Pb and Zn polymetallic deposits, and that the newest aeromagnetic data obtained from the high-precision aeromagnetic detailed investigation in northern Derbur seem to be very useful in the delineation of fault structures, intrusive bodies and altered zones.

The discovery of the Bairendaba Ag-Pb deposit is the newest achievement made by the Inner Mongolia Bureau of Geology and Mineral Resources, and also serves as one of the typical case studies in the discovery of large-size Ag deposits by the integrated geo-physical-geochemical technique since 1950s when geophysical and geochemical work was started. Such an integrated geophysical-geochemical technique deserves wide application on the western slope of central and southern Da Hinggan Mountains in Inner Mongolia.

Beginning with the features of regional geophysical and geochemical fields in Bazinao-Zhanggongshan area, combinied with the available data of regional basic geology, this paper has put forward five Ⅰ or Ⅱ grade potential Au, Sn enrichment zones on the basis of geophysical and geochemical metallogenic conditions of regional strata, magmatic rocks and structures.

Soil natural thermoluminescence survey is a prospecting method for detecting the thermoluminescence intensity of soil samples collected from a certain depth beneath the surface. This paper summarizes the best test conditions for soil natural thermoluminescence survey in Dongshen area on the basis of much experimentation. The conclusions provide reference data for the test condition choice in this area.

The authors found out the distribution regularity of elements in the upper reaches of the Yeerqiang River in West Kunlun Mountains through 1:500 000 regional geochemical exploration, delineated a series of geochemical anomalies, discovered seven metallogenic belts of copper, silver, gold, nickel, lead, zinc, mercury, lithium, tungsten and molybdenum, determined six mineralized belts of copper, silver, gold, lead, zinc on the basis of follow-up of the main anomalies, and carried out evaluation on the protential of mineral resources in West Kunlun region. Researches show that this region has rich mineral resources such as copper, nickel, gold, silver and molybdenum. Targets for further work is put forward, and plentiful geochemical data are provided for basic geological studies as well as mineral resource evaluation in West Kunlun region.

Aimed at solving the problem of the creditability of structure shape in trap evaluation, the authors have advanced the forward modeling for calculating such typical structure models as HQ, DY and BP in Lower Yangtze area by using the finite-element forward modeling technique of seismic wave. The result shows that this technique provides basis for structure determination and trap evaluation and eliminates one-sideness in the interpretation process.

Based on a study of mineral association of sphalerite as well as typomorphic characteristics and physical typomorphic characteristics of elements, the authors have tentatively discussed sources of ore-forming materials, ore-forming temperature and genesis of Houyaoyu, Luotuoshan and Xizaogou Pb-Zn deposits in western Henan.

Based on a study of the relationships between anomalies of regional geochemical deep layer samples, geophysical gravity and magnetic anomalies and remote sensing interpretation, the authors hold that the anomalies of elements in deep layer samples are composed of four parts, i.e., indicator elements for concealed structures Au and Hg, elements of acid rocks related to gravity negative anomalies Sn, Be, F and Y, elements of basic rocks related to aeromagnetic positive anomalies Fe, Co, Ni, V, Cr and elements related to strata Cd, T and Tl. This study has explained the causes of element anomalies from deep layer samples and opened up a new way which combines regional geochemical and geophysical exploration with remote sensing interpretation.

The Deerbugan metallogenic belt, a key area in search for copper polymetallic and noble metallic deposits, has great potential in mineral resources. Nevertheless, no great breakthrough has yet been made in ore prospecting work within this ore belt except for the discovery of the superlarge Wunugetushan porphyry Cu-Mo deposit. Based on characteristics of geophysical and geochemical anomalies of the Wunugetushan porphyry Cu-Mo deposit, this paper discusses the ore-prospecting work on its outskirts and, on such a basis, deals with the further ore exploration work in the nonferrous metallic ore province.

The authors have studied the relationship between soil magnetism and uranium deposits in eastern Inner Mongolia. The results show that the soil magnetic anomalies can be used to locate uranium deposits. Therefore, such anomalies can serve as a direct indicator in uranium exploration.

According to the study of magnetotelluric sounding data in Qiannan-Guibei area, units of different district condtructs were revealed clearly and structural existence of basin and mesa as well as its scope were announced to public.The result shows: In marine-facies area of south China,features of resistivity varies greatly with different lithofacies and lithofacies can be divided by features of resistivity. Meanwhile,through the features of electric fabric of each lithofacies, we can study to scribe layer and reveal some hydrocarbon potential structure. As a living example,hydrocarbon potential structure of Zhe'xiangjie has been turned up In this way.

This paper makes a tentative discussion on the application of AMT method to the detection of shallow sand bodies. With modeling studies and practical examples, the paper probes into the feasibility and effectiveness of AMT method in the detection of sand bodies, and analyzes the transverse resolution of this method. The results show that the AMT method is quite effective in detecting sand bodies in proper circumstances.

Dual-frequency IP instrument is a kind of precise electronic instruments, and its error has strong influence to survey results. In order to check the characteristics of dual-frequency IP instruments, the authors have designed a simple RC-circuit. The authors have done the simulation test, and gotten satisfactory results.

With Hefei basin as an example, this paper has analyzed the variation regularity of geochemical anomalies in different backgrounds and its significance in exploration, put forward the principle for dividing regional blocks and pointed out the great importance of detailed background investigation in geochemical exploration.

Seismic wave field feature of Ordovician carbonate karst reservoir (cave,reef,hole,crack and cranny )in Tahe oil field is thedifference magnitude diffraction wave over weak reflection amplitude,so,the diffraction wave exact imaging and fidelity amplitude processing is the basic of carbonate karst reservoir study.The paper,by the real seismic data high fidelity processing with post-stack high precision migration arithmetic and true amplitude in Tahe oil filed, summed up a set of post-stack seismic data high fidelity amplitude processing technology to adapt the area Reservoir prediction.

Based on the mean values, variances and variation coefficients obtained from the statistical radioactive contents of various stratigraphic units, we can get to know distribution characteristics and migration regularity of radioactive elements, which serve as the basis for geological interpretation of radioactive fields and geological mapping. On the MAPGIS platform, the authors used the VC++ development language to design a computer automatic statistical software for airborne gamma power spectrum parameters on the basis of prior geological data. Such a database can not only make statistics of the mean values, variances and variation coefficients of radioactive elements in every stratigraphic unit but also check the rock naming or boundary accuracy of the stratigraphic units in available geological maps according to the variation coefficients.

The suppression or utilization of the peg-leg multiple wave is a difficult problem in seismic data processing and interpretation. The forward simulation constitutes the basis of suppressing or utilizing peg-leg multiple wave. Using the nonlinear model theory of layered media, the authors developed a method for forward simulation of peg-leg multiple wave. The tentative application of this method to deep seismic data interpretation in the Zhongyuan oilfield yielded some useful results. This method can also play its role in the analysis and processing of seismic elementary wave and the improvement of seismic data resolution.

The results of 3D inversion are analytically compared with the results of applying 2D inversion program to conducting inversion of 3D geological bodies in DC resistivity sounding. The methods for modeling and confirmation of prior information are compared, followed by a comparative analysis of several inversion examples of typical models. In 2D inversion, the precision of location, shape and resistivity is relatively low in that only single section information is taken into consideration. The results of 3D inversion are in good accord with the practical models because such an inversion has synthesized the information of several sections.

Due to the interference of diffraction wave in GPR profiles, especially in the detection of underground pipes, caves or similar anomalies, the processing and interpretation of GPR data have become very difficult. In order to deal with this problem, the authors, according to the unified wave equation form of electromagnetic wave equation and sound wave equation, used three migration methods to process GPR data. They are phase displacement, Kirchhoff integral and finite difference, which had been employed extensively in data processing of seismic prospecting. On the basis of testing and analyzing the model, the processing and analyzing of the filed GPR data yielded good results.

Complex areas are characterized by complex near-surface geological structures, considerable variation in horizontal and vertical direction, fractured geological structures or the appearance of large dip angle old formation. This paper analyzes the main behaviors and the formation mechanisms of the seismic data in this area, and puts forward some processing techniques suitable for such areas, such as static correction, noise-elimination technique, and frequency compensation. Some problems deserving of attention are also pointed out.

In this study, genetic algorithm was combined with ANN theory, and the principle of artificial neural network was utilized to interpret the logging information. In addition, the BP was altered to improve the convergence speed and avoid local minimization. The advanced neural network was also used to establish the network model for log interpretation. Various log and core descriptions were used for the interpretation model of neural network in practice. Log data of several oil wells were interpreted by this model, with good accuracy and application result obtained.

Seismic signals are directly affected by the rock and the physical character of liquid. The extraction of information about rock and deposit from the seismic data is of great realistic significance. There exist nonlinear relationships between the seismic attributes, which are affected obviously by the environment. BP algorithm can establish the high nonlinear mapping between the object and the seismic attributes. GA algorithm can select the survival of the fittest. The BP algorithm can quickly converge, and the GA can globally search the fittest result in all data. The improvement of BP algorithm and the application of the GA+BP hybrid algorithm in inter-bed prediction can achieve a satisfactory result.

Seismic exploration is an important geophysical exploration method for detecting faults and analyzing fault activity in near-site researches on the seismic safety evaluation of quaternary overburden in construction sites. Based on the application example of seismic safety evaluation at Ruanshui Bridge site in Changde, this paper has analyzed the technical characteristics and the means in the application of the method in this field, and discussed some problems in applying the geophysical exploration method to studying the fault activity.

In approaching such problems as theoretical model and resolution in the vertical reflection method for quality inspection of concrete impervious core, the authors proved the effectiveness of the technique in theory, and achieved good results in application. All this has opened up a new way in non-destructive detection of impervious core.