Natural gas hydrate, a new kind of potential energy, is widely distributed in deep-sea sediments and permafrost regions. Geochemical exploration, as one of the methods for exploiting gas hydrates, is becoming more and more important. Based on research results obtained both in China and abroad, this paper deals with the geochemical methods used in exploiting gas hydrates of marine and permafrost regions, and presents the mechanism and the latest research achievements in this aspect.

Analytical signals estimated from total field magnetic anomalies in eastern China and adjacent seas are found to be more accurate in detecting locations, depths, and boundaries of magmatic bodies than original magnetic anomalies. The depth distributions of magmatic sources differ significantly between different tectonic blocks. The North China Craton shows high analytical signal amplitudes and large lateral extensions, but the detected magmatic sources are mostly deeply buried at depths up to 10 km or larger. This indicates strong magmatic activities in the lower to middle crust of the craton from tectonic reactivation. Due to tectonic uplifting and magmatic intrusions, the Sulu-Dabie Orogen has mainly shallowly buried magmatic bodies with depths smaller than 5 km. The Yangtze Block shows predominantly deeply buried magmatic sources, but unlike North China Craton, the magmatic activities in the Yangtze Block appear to be very weak and the calculated analytical signal amplitudes there are very small. The Cathaysia Block and its offshore northeastward extension is dominated by relatively isolated and shallow magmatic bodies (mostly <5 km) that are mainly caused by the subduction of the Paleo-Pacific Plate in the late Mesozoic. Depths of magmatic sources in the East China Sea correlate well with basement uplifts and depressions caused by Cenozoic continental margin rifting. The Ryukyu Archipelago corresponds with a very quiet magnetic zone and shows deeply buried magmatic sources, and these observations support the reasoning that the Ryukyu Archipelago itself is not the volcanic arc from the subduction of the Philippine Sea Plate but is composed of accretionary materials and/or continental blocks separated from the Eurasian Plate by opening of the Okinawa Trough. The true volcanic arc is represented by a volcanic belt slightly to the west of the Ryukyu Archipelago.

A combination of geogas prospecting, radon emanation measurement and soil α measurement was employed in search for the concealed fault in Yala River area of Kangding County, Sichuan Province, which is a potential site of hydraulic engineering. Multi-section measurement composed of 4 measuring lines with a distance of 2 km was performed in a survey area 12 km in length along the Yala River. The intervals between adjacent sampling points along every line were about 20 m. 12 kinds of prospecting data, such as concentrations of several rare earth elements and heavy metal elements in geogas, radon emanation concentrations and α intensities in soil were obtained. The results reflect the actual concealed fault in Yala River area, which consists at least of two branch fault, with the width of each branch fault inferred to be about 40~120 m.

As the significance of geochemical anomalies is affected by some stochastic factors, such as the differences in geological backgrounds and micro-geochemical landscapes of ore deposits, ore deposits frequently lie outside geochemical anomalies. In spite of this, the ore deposits and geochemical anomalies also show their intrinsic relationship. Under the probability of 0.05 of anomalous data, the impact sphere or renormalisation boundaries of geochemical anomalies at the scale of 1∶200 000 and 1∶500 00 should be extended outwards by 5 km and 0.13 km, respectively, from the anomalies delineated by the threshold. Although there exist different relations between anomalies of different elements or different levels of anomalies of the same element and ore deposits, the relationship of geochemical anomalies to their renormalisation boundaries indicates that there might exist some undetected anomalies between the anomalies delineated by calculated threshold and their renormalisation boundaries. This is helpful to improve the effects of applying geochemical anomalies for mineral exploration, and should not be neglected in the prospecting for ore deposits. The correlation lengths calculated from frequencies of different levels of anomalous data of the Daijiazhuang lead-zinc deposit reveal that the scale plays a decisive role in calculation of correlation lengths under the condition that frequencies of anomalous data are less than 10%.

In a selected test area within the Beishan arid desert gobi relict mountain landscape region of Gansu Province, 1:50000 stream sediment survey and soil survey were conducted. A comparative study shows that both methods can obviously and completely delineate ore-related anomalies. In the area of alternate relict mountain and eroded gobi, soil survey can cover larger area and have higher anomaly intensity than stream sediment survey; however, soil survey needs larger amount of work than stream sediment survey. In practice, the choice of proper methods should be based on the development extent of streams and other factors in the work area.

Based on an analysis of gravity and magnetic anomaly characteristics of the Shilu ore district, this paper has summed up the relationship between gravity and magnetic anomaly characteristics and ore bodies, and examined the effectiveness of the gravity magnetic method in ore-prospecting. With the ore-prospecting model, we could guide the exploration in the depth and around the periphery. On such a basis, the prospect area can be extended and the resource reserves are likely to be increased. In addition, the result could provide information for the national mineral resource potential evaluation project.

In this paper, it is shown that the application of an integrated geophysical method in geothermal resources exploration in Jiaxing area in combination with an analysis of geothermal drilling of Well No.2 can verify the effectiveness of the geophysical methods. The authors hold that the Huimin area of Jiashan is expected to become a geothermal field. The detection of hot water at No.2 Well of Jiaxing geothermal field in Jiaxing-Huzhou plain is of great guiding significance in geothermal resources exploration and development.In this paper, it is shown that the application of an integrated geophysical method in geothermal resources exploration in Jiaxing area in combination with an analysis of geothermal drilling of Well No.2 can verify the effectiveness of the geophysical methods. The authors hold that the Huimin area of Jiashan is expected to become a geothermal field. The detection of hot water at No.2 Well of Jiaxing geothermal field in Jiaxing-Huzhou plain is of great guiding significance in geothermal resources exploration and development.

When the resistivity of the parameters is used in geothermal field exploration, the temperature sectional drawing made by the conversion of resistivity parameters to temperature paremeters is a more intuitive graph to show the distribution of underground temperature. When known geothermal drilling is available in the exploration profile, it is possible to use the known temperature drilling to forecast field distribution of the underground temperature, and this is advantageous to determining the distribution of thermal energy storage structure and the position of the drill hole. In temperature calculation, the calculation of initial formation resistivity is related to the surveying method. The choice of the correct calculation of initial resistivity is very important for temperature calculation results. This paper deals with the calculation method for temperature based on resistivity and initial resistivity value of strata, which is important in explaining the geothermal field exploration.

Groundwater in the bedrock mountain area is mainly structural fissure water. As development of the mountain structural fissures has no direction and is easily impacted by terrain conditions, some conventional geophysical technologies have their limitations, which adversely affects the prospecting result. Based on a study of both "TM" and "TE" observation mode response characteristics by the audio magnetotelluric sounding method, the authors have found that the comparative application of two observation modes can obviously lead to know the anisotropy of strata, with the TE observation mode showing better performance in identifying the spatial distribution of structures. Through the practice application in Taihang Mountain area, the availability of the technique has been verified, thus providing supporting technology for the prospecting of structural fissure water in mountain areas.

In this paper, a time domain induced polarization ladder device,i.e.,the dipole-dipole phase IP sounding device,and CSAMT were employed in the study of the Wuniketu lead-zinc deposit in Inner Mongolia to verify the effectiveness of the comprehensive electrical survey in search for skarn lead-zinc deposits.The results show that,in the measurement of the induced polarization,attention should be paid to the power supply electrode and the relationship between the anomaly bodies,otherwise it will create a false anomaly.In areas with relatively good electrical circumstances of rocks and minerals,the induced polarization area measurement can reflect the abnormal distribution of the sources.Under the condition that the ore body and the rock have not significantly different resistivities,CSAMT sounding can basically better deduce the spatial location of the ore body in comparison with the Phase IP sounding.Therefore,the time domain induced polarization ladder device and the CSAMT electric method can play a greater role in the exploration of nonferrous ore deposits.

Fluorescence spectrometry is commonly used to determine polycyclic aromatic hydrocarbon and evaluate the migration of oil and gas as well as the properties of base oil. Lying in western China , Xinjiang is almost covered with snow in winter. According to the geographical climatic environment in combination with the low detection limit and high sensitivity of fluorescence spectrometry, the authors analyzed the snow and the soil below it along a profile in a known oilfield in Xinjiang by means of fluorescence spectrometry. The results of two-dimensional fluorescence spectra, constant-wavelength synchronous fluorescence spectra and three-dimensional fluorescence spectra are compared with each other and discussed in detail. The comparison results shows that snow can quite effectively adsorb the polycyclic aromatic hydrocarbon and have an abnormal indication for the oil and gas reservoir. These findings can provide some reference for the exploration of oil and gas reservoirs in unknown geographical climatic environment areas in the future.

With geophysical logging applied at Shuanglong well field of Xishui County in the Qianbei coalfield as an example and by utilizing known coal seams or beds of interest and adopting such methods as geological boundary characteristic method, geological marked bed characteristic method, coal seam sequence interpretation characteristic method and coal seam inter-layer distance comparison characteristic method, the authors made a comparative analysis of logging anomaly characteristics revealed along a single curve or multiple curves of physical parameters and summed up common interpretation methods and experience obtained in coal seam judgment and coal seam sedimentary sequence numbering so as to determine coal resource reserves.

This paper explains the forward and inversion methods, which include ray-tracing based on the shortest path ray-tracing method and inversion calculation based on LSQR. The authors made detailed researches on the two algorithms, rebuilt the original image of underground structures, with fairly good effect obtained. Exemplified by engineering application, the results indicate that cross-hole seismic tomography can reflect underground conditions and also provide more concrete data for the study of geological structure and final-period construction. The resolution of the cross-hole seismic tomography is discussed, and the factors affecting the image quality are indicated.

Identification and evaluation of the reservoir flow units is an important aspect of geological research of development mature oilfield. In this paper, take Sulige Gasfield He8 Group as an example, based on the sub-layer and detailed sediment study determined the characteristics of 10 variables to identify and rank reservoir flow units. Based on neural network algorithm of cluster analysis method to identify reservoir flow units of non-linear model. The established the neural network model can be more comprehensive consideration of various geological factors and the flow units. Using the established model, we can identify flow units for the well without boring, which can better solve the mature oilfield reservoir description abundance of information and accuracy requirements. Quarry applications indicates that in view of Chinese oil reservoir's main causes of continental origin, carry out reservoir flow units quantitative evaluation to matured oilfield have greater practical value.

Multiple wave field characteristics of coal mined-out areas in the loess plateau, which include reflection, diffraction, and both natural and artificial surface waves, were studied in this paper. By use of these characteristics, seismic prospecting can detect mined-out areas.

The factors affecting the accuracy of bathymetric survey was analyzed in this paper. The errors in bathymetric survey mainly include instrument error, velocity error, tidal observation error, ship speed error and vessel factors. Based on a comprehensive analysis of causes of the measurement errors, this paper puts forward measures to improve the measurement precision, gives examples and points out maters needing attention in application.

A model with topography was designed. Using the finite difference method, the authors studied the effects of topography on the apparent resistivity and phase curve of MT. Through an analysis and study of distortion curves of simulating models, a number of useful conclusions have been reached. It is shown that the apparent resistivity of TM mode is more easily affected by terrain than that of TE mode, and is more easily distorted at the top than on the bottom of a hill. Meanwhile, theoretical model and real data processing results indicate that the two-dimensional inversion with terrain is very effective and suitable to eliminating the effect of topography on the MT responses.

here exists change of gradient for earth magnetic intensity in directions of altitude and latitude, and hence it is needed to carry out altitude correction and altitude correction during the performance of high-precision magnetic survey. The common method for calculating correction values is based on the thirteen-stage approximate formula of the spherical harmonics expression, and there also exist the ten-stage one and the one-stage one. There commonly exists a small error in using the ten-stage one. In comparison with the thirteen-stage approximate formula, there is a small error in using the ten-stage approximate formula: when there is 30 km between the base station and the measuring points, the error for latitude correction is -0.21 nT; nevertheless, there is a large error in using the one-stage approximate formula: when there is 4 km between base station and the measuring points, the error for latitude correction is about 1 nT, and when there is 300 m in height between the base station and the measuring points, the error for altitude correction is about 1nT.

Nowadays, there is no unified cognition of relative amplitude-preservation processing, which nevertheless is the basis of reservoir lithologic exploration. Systematic analysis of key processing technique is poor too. Based on years of experience obtained in real data processing and an analysis of the difficulties existent, the author put forward several criteria and then further analyzed such key techniques as amplitude processing, noise attenuation and resolution improvement to obtain the pros and cons in amplitude-preservation. The results may have certain referential significance in further data processing.

This paper has summarized the development situation and existing problems of the geoelectric chemistry method, and analyzed ideas and ways to improve this method. On such a basis, the authors have designed and developed "solid carrier elements extractor", which takes solid materials as the carrier. Such an extractor has advantages of handiness, practicality, and high efficiency. Furthermore, it has already sufficed for mass application.

The implementation of an up-to-date multi-channel radiation detecting system based on WSN(wireless sensor network)is presented in this paper. The technical points of software and hardware, such as using G-M tube as a detector, time-to-count measurement method and WSN, are also described in detail. Wireless sensor network is the one with which a number of sensor nodes are self-organized through wireless communication. And it can implement data detecting, acquiring, processing and transmitting real-timely and concurrently. For the purpose of improving the reliability of data transmission, the system is made up of three-tiered heterogeneous architecture consisting of detecting node, sinking node and central control node.

In Lanzhou-Baiyin area, the composite effects of various natural and geological actions and human activities have resulted in obvious nonequilibrium in the distribution of nutritional elements as well as toxic and harmful components in the surface layer soils. A quality assessment of agricultural soil in this area was conducted based on the content distribution of elements determined by soil-dominant multi-media geochemical measurement and the investigation of current situation of soil pollution together with the abundance of beneficial elements. It is concluded that the ecological risk and the discrete intensity of enrichment pollution of heavy-metal elements Cr and Ni are relatively weak, while high discretization of Cd, Hg, Pb ,Zn, Cu and As exists. The agricultural soil has been divided into three levels, i.e., excellent level (first level), general level (second level) and bad level (third level), and some principles of fertility and measures for remedy have been brought forward accordingly.

With central south Hebei plain as the study area, the authors studied geochemistry of fluorine in detail and explored its controlling factors. The results show that the fluorine content in central south Hebei plain is on the whole high, and the distribution is not uniform, having significant zoning characterized by four high and four low fluorine regions. The distribution of fluorine element in the area is significantly affected by physical geographic factors and artificial factors, with the natural geographic factors play the leading role. In the natural geographical factors, landscape is the main controlling factor, whereas in human factors, fertilizer seems to be the dominant factor.

Based on surface characteristics of the regional beach shallow transitional zone of Qingdong 5 area and a detailed analysis of original data, the authors adopted quadratic secondary location, cross correlation, model method amplitude regulation and prestack time migration key techniques to study and tackle such problems as drag cable drift, different epicenters and detector differences as well as ecotone amplitude energy abnormal phenomena. These technologies can effectively eliminate the inconsistency of beach neritic information in such aspects as amplitude, frequency and phase and achieve good imaging effect. The achievements obtained provide support for regional petroleum exploration.

The quantitative intersection technique is widely used in oil and gas exploration and also plays an important role in the recognition of reservoir fluid. This paper deals with the multi-parameter optimization method. Through calculation, highly-sensitive parameters can be obtained and, on such a basis, fluid attribute sensitivity is analyzed, thus avoiding multi-interpretation and uncertainty in multi-parameter choice. With the global survey-based 25-data set published by Castagna and Smith as the model, the authors made 3D intersection analysis with optimized parameters, and attained good result in reservoir recognition.

In the airborne electromagnetic survey, the altimeter data of transmitter coil are often inaccurate, which can affect the inversion result and give spurious anomalies. To overcome these shortcomings, this paper presents a 1D inversion method of airborne electromagnetic data in time-domain for inaccurate observed transmitter height. The inversion algorithm, using observed voltage data, can invert geo-electrical parameters and transmitter coil height simultaneously. The algorithm applies a regularized inversion algorithm to overcome the typical ill-condition inversion problem, and the regularized factors are calculated with an adaptive style based on the relationship between the data object function and the model object function so that the iterative inversion can be steadily carried out. The validity of the inversion method was tested using the helicopter airborne electromagnetic data as an example in this paper, which was performed by adoption of theoretical model response data with the addition of random noise. The inversion result shows that no mater whether the initial height value is higher or lower than the true value, the inversion algorithm can reconstruct subsurface medium parameter and transmitter coil height very well. The more accurate the transmitter coil height used as the inversion initial value is, the faster the convergence rate of inversion iteration and the better the inversion effect will be.

In regional geochemical exploration, the sampling-point layout map is a necessary component part; nevertheless, artificial coding is not a very easy task. Based on many years' drawing experience, the authors tried to find the characteristics of computer program's automatic processing and to analyze the locations of the sampling points specifically. The generation of large lattice coding map layer according to the necessity is proved to be useful in improving the efficiency and quality of the work.

The traditional way of single bore wave testing is to make excitation on the ground and receive the signal in the bore, which causes the limitation of the test depth and reduce the test accuracy. In offshore drilling it can not achieve the recitation at all. Therefore, a new technique is required to obtain the shear wave for wave testing in offshore drilling. The hang wave logging method described in this paper puts both source and detectors into the borehole, thus getting rid of heavy ground source and realizing the convenience of the wave logging equipments. It is a one-double device. In this method, two detectors are used with the interval of 1 m to receive S-wave propagation signal and then determine the formation wave velocity of the borehole through using the S-wave arrival time difference by the sensor. The method played an important role in the platform survey of the Nanpu oilfield. The authors carried out shear wave logging for a borehole 120 m in depth and obtained a good testing result. The results provided accurate shear wave velocity for the project and played an important role in dividing the field soil types.

Due to the tunnel cavities and a variety of engineering facilities in the tunnel, the resistivity anomaly is subject to serious distortion, which will increase the difficulty of data interpretation and accurate locating of the abnormal body. In this paper, the finite element method was used to calculate the tunnel environment response,the resistivity calculation method under the special tunnel condition was analyzed, and computer modeling experiments were conducted. And then, according to the environmental anomalies in different survey lines, three different models were designed to calculate the effect of tunnel environment on the detection of surrounding abnormal bodies. The ratio method, difference method and integrated correction method which are used for reducing the false anomaly resulting from tunnel environment were employed. The results show that it is necessary to remove the tunnel environment anomaly before the interpretation of measured data, and the above methods can be used to eliminate the environmental influence of the tunnel.

The tunnel DC resistivity advanced detection method is a method based on the theory of equipotential spherical surface that is excited by point source in full space. Due to the existence of a considerable impact from tunnel and detection environment when the measurement is performed at the rear of the heading face, difficulty in data interpretation is largely increased. On the basis of vertical ground resistivity sounding and side DC logging technology, the authors proposed a vertical focused advanced detection project which is suitable for tunnel space. The finite element numerical simulation method (FEM) was used to simulate the effect of focused advanced detection method in three-dimensional tunnel space. Compressed storage technology and preconditioned iterative algorithm could greatly improve the efficiency of forward modeling as well. A comparison between the FEM modeling results and the physical simulation results in a soil bin shows that the accuracy of forward simulation can meet the requirement, and the vertical focused device can attain the purpose of focused advanced detection. The results of simulated complex models under the condition of vertical focused observation show that the scheme can effectively detect ill geological bodies in front and side tunnels.

The mine transient electromagnetic method is one of the geophysical methods for effective investigation of the situation of water in front of the tunnel. Rapid processing of data and display mapping can make the mine transient electromagnetic method play a better role in the underground exploration work. According to the detection device and technology of advanced detection in front of the tunnel,this paper deals with the steps of data processing and display mapping in the advanced detection method, achieves the coordinate conversion of data, and generates a more intuitive sector chart which is consistent with the actual detection area.

In this paper, the receiving wave types and speed parameters of GPR were discussed, the interference information was determined, and the examples of utility poles, overhead lines, mountains and other interference objects were analyzed. According to the differences in arrival time and propagation velocity, filtering processing of the interference was made by means of deconvolution, F-K  filtering and shifting. The results show that the multiple wave interference, curved interference and horizontal interference can be effectively filtered, thus highlighting the effective wave. It is proved that this method is feasible and effective.