Accurate estimation of the gas hydrate saturation within submarine sediments is a key problem in reserves calculation. Based on summarization of a set of latest related publications, this paper advances three kinds of methods for estimating gas hydrate saturation within submarine sediments, i.e., pore water chlorine ion concentration of the core, well-log and seismic velocity. The merits and shortcomings of these methods are also evaluated.

Backed by the large-size Dachang Gold Deposit, the authors made a preliminary study of the supergene process in the western part of the cold and high meadow area in Qinghai Province.It has been found that eolian sands are concentrated in-40 ~ +160 mesh and rich in SiO₂,while contents of most elements are very low.Most of the indicator elements for gold deposits are basically concentrated in residual soil and clinosol of-20 mesh and meadow surface soil of-5~+20 mesh,representing proximal sediments.The contents of the gold indicator elements Au,As and Sb tend to decrease in order of bedrock→residual and slope sediments→meadow surface soil→stream sediments,and things are similar for other elements.All this indicates that there exist geochemical processes of impoverishment or homogenization of elements,especially Au,As and Sb,on the surface of cold and high land peneplain-hilly landscape.

A comparative study of sampling media for ultra-low density geochemical investigation was conducted in Jiayin area, a typical forest-swamp landscape area in central Heilongjiang. A comparison between flood land sediments and active stream sediments reveals that the anomalies delineated by flood land surface sediments can not only indicate mineralization information but also reflect geological setting of the study area, whereas anomalies delineated by stream sediments are rather weak and can only reflect the information of exposed ore deposits. Studies show that surface sediments of the flood land seem to be the best sampling media in ultra-low density geochemical investigation in forest-swamp areas.

The application of geochemical precise survey technique to detecting carbon dioxide anomalies is based on the theory of oil and gas infiltration.Using such geochemical comprehensive indices as CO₂ in soil,CO₂ in water,CO₂ alteration,soil total hydrocarbon, mercury,isotopes and fluorescence in combination with geological-geochemical data,we can predict the distribution of CO₂ gas accumulation.Based on an integrated analysis of geochemical data and distribution of gas accumulation in Haugou area of Jiyang depression and a study of regional geochemical background,the authors indicate the regional and zonal anomalies.Taking into account the oil and gas geological and geophysical data,this paper has also made grading evaluation of delineated geochemical anomaly areas,predicted zones favorable for CO₂ accumulation,and probed into the effective application of integrated geochemical precise survey technique to detecting carbon dioxide accumulations.

As one of the major methods for oil and gas geochemical exploration, the hydrocarbon acidolysis technique has acquired obvious results in oil and gas exploration. Nevertheless, the application results of this method are affected by quite a few factors. Employing the mathematical statistic method to study interference factors and interference-suppressing means, the authors have made some achievements. Using the hydrocarbon acidolysis indices after interference suppression, we can classify characteristics of regional geochemical fields of major oil-and gas-bearing basins in China, predict and recognize oil and gas accumulations and reservoirs, and reveal vertical micro-migration of hydrocarbons.

Petrophysical parameters of Picheng Rock Group were obtained for the first time through measuring bore samples of ZK03 hole, which included density, susceptibility,remanent magnetization, resistivity and polarizability. The density of Picheng Rock Group is 0.15×103 kg/m³ higher than that of the surrounding rocks and makes up a precondition of gravitational exploration. Picheng Rock Group has high resistivity and show obvious resistivity difference from part of surrounding rocks, and hence resistivity exploration can be conducted under certain conditions in this area. The magnetic method and IP method must be used with care because of low magnetic properties and low electrochemical activity of Picheng Rock Group.

Based on a study of regional structures and geological conditions of Yunshan anomaly area and an analysis of geophysical and geochemical data, the authors hold that this area deserves much attention in future. It is pointed out that the study of the geological cause for the magnetic anomalies in the anomaly area will probably bring a favorable turn in the analysis of these anomalies.

The Yinkengshang uranium ore spot occurs on the southeastern margin of Jinlongzhang volcanic basin in southern Jiangxi Province, whose orebodies have been controlled. There exist obvious wall rock alterations such as hydromicatization and hematitization. Compared with those in the wall rocks, the Al₂O₃ and SiO₂ in the ores decrease evidently, but the Fe₂O₃ (FeO), MnO, CaO, S and Cl increase. Mo, Th and Ag are main associated elements, with the highest Mo content more than 1%. According to the mineralization-alteration assemblage features, it is considered that this ore spot belongs to the magmatic-hydrothermal ore-forming type located at the top of the magmatic-hydrothermal ore-forming system.

Soil natural thermoluminescence survey with very good repeatability can be used in exploring deep deposits. The tentative application of soil natural thermoluminescence survey to a volcanics type uranium deposit is presented in this paper. The result shows that obvious anomalies exist above orebodies, and weak anomalies are above barren bodies. Strong anomalies are also found in some of structure zones, fractures and faults. Important clues can be detected through using the soil thermoluminescence survey for evaluating volcanics type uranium resources.

CSAMT is a frequency magnetotelluric method. This paper describes its measurement and data processing mechanism and also reports its application achievements in several known in-situ leachable sandstone type uranium deposits in Xinjiang and Inner Mongolia.

In this paper, the authors used different gliding windows to perform Euler deconvolution on magnetic profile data or 2-D model, probed into the relationship between structure indices and solutions and the method for eliminating the poor solution on 2-D model by mathematical statistics. The Eular deconvolution on magnetic profile data was successfully conducted in a certain area of northwestern China.

Based on a study of regional structures and geological conditions of Yunshan anomaly area and an analysis of geophysical and geochemical data, the authors hold that this area deserves much attention in future. It is pointed out that the study of the geological cause for the magnetic anomalies in the anomaly area will probably bring a favorable turn in the analysis of these anomalies.

Based on experience acquired in practical work, the authors deal in this paper with the troubles of the Summit digital seismograph produced by DMT Company of Germany that are likely to occur in field work and the methods for their in-situ repairs.

Based on experience acquired in practical work, the authors deal in this paper with the troubles of the Summit digital seismograph produced by DMT Company of Germany that are likely to occur in field work and the methods for their in-situ repairs.

This paper describes the present situation of magnetotelluric researches abroad, emphatically sums up the situation of 2D magnetotelluric inversion studies, and enumerates the inversion methods currently commonly used in foreign countries. The development trend of magnetotelluric inversion interpretation is also discussed in this paper.

This paper has discussed the method of normalized full gradient of gravity anomaly in wave-number domain and suggested the introduction of smoothing filter operator in the process of downward continuation and derivation for potential field conversion. This technique helps increase the reliability and stability of calculation and extend the depth of continuation. Based on lots of model experiments and data analysis, the authors have determined the experiential value of exponential parameter about smoothing filter operator in calculating downward continuation and derivation, and pointed out the variational regularity between the depth of the geologic body and the harmonic number N: the lower (deeper) the depth of geologic body, the bigger (lesser) the value of N. It is also discovered that there exist similar characteristics of contour G^H field between the three dimension model of symmetrical density anticline and asymmetric oil storage anticline and the two dimension model, and this offers the new thought for calculating the center of gravity and investigating the oil storage structure.

The deciding weight theory of Principal Components Analysis is used to compute contribution values of seismic attributes to forecasting parameters, and the attributes sensitivity analysis is solved by getting rid of these attributes with lesser weight coefficient. In this way, the association between reservoir parameters and attributes is established. By means of K-L transform, higher dimensional attributes are mapped to lower dimensional ones while correlation between attributes is eliminated, thus completing the optimization of attributes. In this paper, the target parameters are predicted by BP neural network. The application shows that the dual optimization method combining Principal Components analysis with K-L transform overcomes the limitation of either method and at the same time possesses their respective merits. In short, the method gives a satisfactory solution to the sensitivity analysis, association, and combination optimization of seismic attributes, and eventually improves the precision, speed, and efficiency of reservoir prediction.

Considering the low signal-to-noise ratio characteristics of seismic data from the Tarim desert area, the authors have put forward a suite of techniques suitable for processing low signal-to-noise ratio seismic data from the desert area. The problems like static correction and denoising before stack in this area have been solved. Practical processing proves the techniques to be effective.

Given the velocity of low velocity layer (direct wave) and by means of the first break information of production shots and the static correcting mathematical model based on the weighted least squares and conjugate gradient method, we can calculate the static correction values of the long and the short wavelengths on the basis of iterative algorithm. This technique is obviously effective in solving the unreal minor structures in north Ordos basin.

According to the data characteristics of mineral resources exploration, this paper has studied the volume rendering algorithm model and the spatial interpolation method suitable for 3D visualization of geological information. Based on IDL platform, the authors developed the software for 3D visualization,which can display rapidly and exactly the lithological and physical properties of the geological body. In addition, the checking of the 3D visualization techniques was completed based on the borehole data of a metallic deposit in Inner Mongolia, and the effects prove to be satisfactory.

Database technology is very useful in realizing MT data management. In this paper, a visualized systematic frame of MT data processing is described for the first time. On such a basis, the emphasis is placed on the process of constituting the database platform with the Paradox database system. With mixed language programming and Windows API technology for realizing the utilization of Fortran and Surfer in Delphi, this paper also deals with the implementation scheme of MT data processing function. A visualization program of MT data processing based on such objects as survey area, survey line and survey point is realized.

In dual frequency IP ore-prospecting work, the basic principle of fuzzy mathematics was used to make a comparison between the known electric profile and the unknown profile. As a result, the geophysical anomaly most approximating to that in the known profile was found in the unknown profile, which provides grounds for ore prognosis and drill hole arrangement.

This paper has described basic principles of the ultrasonic transmission testing technique, described the result of the test on the basis of some examples, and pointed out some problems to which proper attention should be paid in the test.

The Rayleigh wave technique is a new geophysical method for locating rock and soil. With its dispersion characteristics,speed of propagation and physical-mechanic properties, it can solve many engineering geological problems. This paper describes the utilization of this method in the quality inspection of the foundation treated by dynamic consolidation in No.1 construction site of Green-Cool (Nanchang) Science and Technology Yard. Some anomaly zones of low speed were found. It is pointed out that the foundation soil bearing capacity doesn't meet the designed requirements and hence some proper measures should be taken to strengthen the capacity. The effectiveness of the method has been proved by coring, light trigger exploration and civil engineering test.