Geochemical exploration is dominated by regional geochemical exploration and multi-objective regional geochemical survey, carried out integrated operation of high-density large data, large information, and obtained remarkable achievements in the aspects of resources and environment during '12^th Five-Year Plan'(2011-2015).These achievements have produced extensive influence and important economic and social benefit, and hence exploration geochemistry has become the most active field in geological work. The general framework and scientific system of modern exploration geochemistry have been gradually established with the investigation as the basis, the theory as the guidance and the integration of resources and environment into one body. In the ecological field, the investigation system, theoretical system, evaluation system, pre-warning system, restoration system and method system have been established with the nationwide multi-purpose regional geochemical survey as the basis and the ecological geochemical theory as the guidance. All these achievements mark the maturity of the discipline. This paper describes in brief the composition, connotation and interconnection of the exploration geochemistry framework and system. In addition, some new thinking and new concepts related to this field are put forward for discussion.

In order to study the ore-potential of the area around the Xiaohe rock body in southern Xiaoqinling, the authors chose 1∶50 000 8-Yi 3AgWBi stream sediment anomaly, Meso-Proterozoic Xiaohe rock body and F1 fault at the contact zone of Meso-Proterozoic Buandaokou Group to conduct geological, geophysical and geochemical integrated exploration. Soil survey led to the discovery of the Zhangjikou 1-Jia 3 Ag Au Sb Zn Pb As Co Cu Mo B composite anomaly characterized by relatively good element combination, large anomaly area and high intensity, in which the highest value of Ag is higher than 20×10^-6, with distinct three-grade concentration zoning and relatively strong concentration center; IP sounding predicted that F1 fault extends downward, surface trenching discovered a silver orebody at 1-Jia 3 anomaly in F1 structural alteration zone, and drilling revealed the existence of a thick and large Ag-Pb-Zn orebody. The discovery of this ore deposit has realized the ore-prospecting breakthrough at the southern edge of Xiaohe rock body, and also serves as a typical example of the application of the geological, geophysical and geochemical integrated exploration.

During the period of 2007~2015, lots of geological and geophysical survey work was carried out in Nanmentou area located in the north of Ningwu basin. On such a basis, researchers provided experience and advice for guiding deep ore prospecting in Yangtze Region. There are multiple solutions of geophysical data interpretation in the process of research. In the project implementation process, some drill holes which were designed according to the comprehensive anomalies (especially the geophysical anomalies) produced prominent effects, but some failed to show satisfactory results. The work to sum up the experience of failure and success of the arrangement of drilling is very important. On the basis of analyzing the petrophysical data of different lithologies in this area, the gravity and magnetic data were processed and interpreted, the factors causing gravity and magnetic anomalies were summarized, and a new view for distinguishing rock masses, volcanic rocks, exploration breccia pipes, volcanic channels and the distribution of fractures in this area was set up. In this paper, according to the characteristics of the CR and CSAMT electrical profiles, gravity and magnetic anomalies, as well as drill hole curves (physical and logging), the authors summed up geophysical anomalies, and the results have reinforced the understanding of the deep geological structures in this area and enriched the geophysical anomaly interpretation experience. Through the study of second time interpretation of electrical prospecting and gravity and magnetic anomalies and a comprehensive analysis of the previous data, the experience in geophysical interpretation has been enriched, which may have some directive significance for the application of exploration technology to the prospecting for deep deposits in Yangtze Region.

Using supercritical CO₂ fluid extraction technology for the extraction of polycyclic aromatic hydrocarbons from oil and gas geochemical exploration samples and using fluorescence spectrometer to conduct verification show that the repeatability and stability are relatively satisfactory with RSD less than 5%. Compared with conventional geochemical cold extraction method, this technology shows obvious advantages. Following the analysis of data obtained by supercritical CO₂ extraction technology in Nanyang N65 well profile and a comparison with the geochemical exploration indexes such as headspace light hydrocarbon and acid-extraction hydrocarbon (SAEH), the authors carried out surface geochemical exploration in the Black Dragon Temple in Nanyang depression area, and found that the supercritical carbon dioxide technology would be helpful to the delineation of accumulation areas for oil and gas.

Prospecting potential is good in Mwombezhi area of Zambia.Two geochemical anomalies were delineated in the pre-searching of copper-cobalt ores in this area.IP measuring,trenching and drilling means were applied to verifying anomalies in some key sections.The results show that the anomalies are caused by mineralization,and the plagioclasite hornblende schist is the ore-bearing bed.Ten orebodies were delineated.Combined with the soil geochemical anomalies,IP anomalies and stratigraphic distribution,the authors infer that there exist thousands of meters of ore-bearing bed.The Cu-Co geochemical anomalies can effectively reflect the presence of copper and cobalt mineralized bodies.The soil geochemical survey method is proved to be applicable to the local landscape conditions.It is shown that the application of soil geochemical survey method to local landscape conditions is accurate,effective and rapid,and can be popularized and applied to Cu-Co prospecting in Zambia and some similar areas in central and southern Africa.

Volcanic rock type uranium deposits could be generated in volcanic rock body and also from shallow metamorphic rock and volcanic rock mass near the lower Palaeozoic strata in the Mesozoic continental glutenite, so the detection of the development situation of related volcanic rock body is of great significance for the further development of uranium exploration work. This paper briefly introduces the controlled source audio-frequency magnetotelluric (CSAMT) measurement and the work method of high precision magnetic survey and ground in the five camps in practical application. Combined with the geological data and petrophysical characteristics, the authors used CSAMT survey data, found out the general andesitic porphyrite and thick deep development characteristics of the porphyry, and made use of the ground high-precision magnetic survey data, thus improving the recognition reliability of the contact zone of rock mass and fracture structure inference. Drilling verification shows that the effect is good. Comprehensive analysis shows that CSAMT survey has better vertical resolution, and can accurately detect the deep development of rock mass characteristics, the location of the fracture development and the deep situation; the contoured ground high-precision magnetic survey can roughly delineate rock mass, and identify the contact zone of rock mass as well as the fracture. The two methods together can more comprehensively solve geological problems and provide effective technical means for volcanic type uranium deposit exploration.

Longhui County in Hunan Province is a national poverty area. Jingzhi Village in this county has an arid area. Sandstone and shale of Longtan Formation are exposed extensively in the village, and the distribution of limestone is very limited in the northwest and the south. In addition, the relatively high ground level leads to surface water scarcity, which seriously affects the normal life of local villagers. To solve the problem of drinking water in this area, the authors carried out a comprehensive study of the topography and geological features of the area and, on such a basis, employed the high-density electrical method, AMT sounding and IP sounding methods and arranged drill holes ZK01, ZK02 and ZK03 These three holes all meet water, with the outburst water quantity being respectively 32 m³/d, 347 m³/d and 256 m³/d, thus solving the problem of drinking water. It is proved that the comprehensive geophysical method is effective in the exploration of groundwater resources in this area.

The Yinnao deposit is located in the west of the Yinkeng Au-Ag polymetallic orefield. The main mineral type is altered rock type in the fracture zone. According to the results of the soil mercury gas survey, the study area shows a significant anomaly with the maximum content of 5 200.00 ng/m³ and the largest peak/background ratio is 13.4. The anomaly shape is consistent to the NE-trending ore-controlling structure, and shows a anomaly superposition feature. Combining the distribution of mercury anomalies with ore-forming geological conditions, the authors delineated three metallogenic prospective areas, with the Ⅲ prospective area exhibiting the greatest prospecting potential.

Natural gas hydrate lateral velocity distribution is not uniform, and has a close relationship with the faults,carbonate rock,seepage and salt diapir structure;therefore,geological imaging obtained by the time offset is not accurate.It is hence necessary to obtain geological imaging in the depth domain by depth migration.The velocity model in the depth domain is optimized by tomography,which is widely used at present because of its high accuracy and reliability.In this paper,a high precision grid tomography method is used to optimize the pre-stack depth migration velocity model.The residual curvature analysis (RCA) principle is described.The steps and methods of using high precision grid tomography velocity inversion method to optimize interval velocity model in the depth domain are introduced in detail.The application effect of the actual acquisition of quasi three-dimensional Xisha hydrate seismic velocity model shows that this method has high operation efficiency,significantly improves imaging accuracy within the fault zone,shows fracture structure more clearly,and obviously changes wave group characteristics for the better,as can be seen in the migration profile.

The formation pore pressure is the reflection of the energy of oil and gas,and is the driving force for oil and gas migration in the reservoir.It is very important to accurately predict formation pressures in oil and gas exploration and development,especially in deep gas exploration and development.Using seismic data,logging information and geological information to predict the pressure coefficient can be divided into three steps:First,based on well logging curve of multi-well mudstone,the normal compaction interval velocity is calculated by polynomial fitting;Second,for the purpose of obtaining the accurate interval velocity body,a geological framework and the well-constrained seismic inversion are established based on the geological understanding of the region;Third,the formation pressure coefficient is calculated by the derived Fillippone method.The progressive exploration of Qibei slope confirms that the prediction of pressure coefficient has the characteristics of minor errors and high accuracy,thus providing a powerful basis for deep gas exploration.

In the case of global climate change and global warming,permafrost degradation on the Tibetan Plateau will result in great changes of the hydrogeological conditions,which is likely to seriously affect the regional water cycle and ecological environment.The purpose of carrying out research on the geophysical exploration technology is to realize the understanding of geophysical characteristics and the spatial distribution of permafrost.In view of the above situation,6 kinds of technical methods,i.e.,seismic-reflection,converted-wave seismic survey,seismic-refraction,geological radar and audio magnetotelluric survey (EH-4),were compared with each other and analyzed through experimental study.The results show that 6 kinds of geophysical exploration methods can detect permafrost structure,geophysical characteristics,spatial distribution of permafrost and some other geological phenomena;nevertheless,all kinds of technical methods have certain limitations.According to different target tasks,the authors put forward a combination model of three kinds of geophysical exploration methods to detect permafrost in the Tibetan Plateau.This combination model provides technical supports for the geophysical exploration of the permafrost in the Tibetan Plateau.

Manzhanggang gold deposit is epithermal gold deposit newly discovered in recent years, in Qinghai Province. Based on field work and used of polished thin section identify、chemical composition analysis、electron probing analysis、phase analysis.et al,think of the deposit has quartz veins, altered tuff type, broken altered rock type three ore types. Ore structure have porphyritic texture、cataclastic texture、idiomorphic-hypidiomorphic texture、allotriomorphic-granular texture,and ore structure have massive structure、impregnation structure et al.Natural gold distribution of intergranular gold, granularity concentrated on -0.15+0.074 mm and -0.04+0.01 mm, the distribution law were 38.99% and 42.05%, easy to monomer dissociation and Conducive to its beneficiation enrichment. Used Nelson re-election if ore grinding fineness -0.074 mm when accounting for 60.55%,no cyanide leach to tailings. Finaliy, The total gold recovery rate of 98.63%.

Differential semblance optimization (DSO) is an approach to the inversion of the velocity which avoids the severe convergence associated with nonlinear least-squares inversion.DSO method-based wave-equation migration velocity analysis measures the focusing or flatness of image gathers and uses the deviation as the criterion to update the velocity.The DSO objective function has a decent global convexity property,therefore it can avoid the local minima problem,the gradient of objective function is smooth,it can inverse the background velocity accurately when there lacks low frequency data.Generally,ODCIGs is used to construct the objective function.In this paper,the authors use ADCIGs to construct the objective function,and the result of the test shows that DSO method with ADCIGs can estimate the correctness of velocity model directly and reflect the coupling relation between velocity and depth accurately.

Born approximation describes the primary scattering response of perturbed medium,which is the basis of linearized seismic inversion.Based on Born approximation,we derive the primary reflected wavefiled propagation formula by expressing the Green's function as a Gaussian-beam summation.The simulation of primary reflected waves is called Gaussian-beam linear forward modeling.On this basis,we perform numerical test by using the diffractors model,the glutenite model and the irregular surface model, and compare our results with those generated by wave equation modeling.Besides,we implement migration with corresponding synthetic seismograms generated by Gaussian-beam linear forward modeling.Numerical results indicate:First,Gaussian-beam linear forward modeling can accurately produce recorded data with multiple and the direct wave muted;Second,migration with synthetic seismograms generated by Gaussian-beam linear forward modeling can image corresponding subsurface structures;Third,target-oriented modeling can be carried out naturally.

Pre-stack seismic reverse time migration has important application in high accuracy subsurface imaging.However enormous memory is needed in RTM.Using random boundary in RTM can reduce memory need of RTM effectively.In this paper,random media expressed by correlation function,correlation length,root mean square velocity perturbation is used,the meanings and values of parameters are analyzed and the optimal parameter group(exponential correlation function,the correlation length being equal to wave length and root mean square velocity perturbation being 30%) are obtained.Numerical simulation shows that using random boundary with optimal parameter group can destroy the coherence of artificial boundary reflection wave fields effectively and obtain high accuracy imaging result with less memory at the same time.

In recent years,the success rate of turbidite reservoirs in Dongying depression is reduced,and the existence of gray matter is the main factor affecting the prediction accuracy of turbidite reservoir.In order to accurately identify the turbidite reservoirs in the gray matter development area,the petrophysical parameters such as the velocity,density and Lame parameters of sand,gray and mudstone are analyzed and using the histogram technique to select the effective lithological recognition factor F in the region.The AVO equation is deduced based on the sensitive reservoir recognition factor and F according to the Aki-Richards approximation equation.The prestack elastic impedance equation based on lithology recognition factor F is obtained by using Connolly pre-stack inversion method.The equation is used to analyze the model and the actual data and the results show that the method can effectively identify the turbidite reservoir in the gray matter development area.

In seismic exploration,the random noise severely distorts and interferes with seismic signals,and hence the denoising process is very important.In order to meet the high-precision requirement,the authors,based on the sparse and redundant representation theory,improve the dictionary update stage and the sparse coding stage in the conventional dictionary learning algorithm.While keeping the supports intact,the dictionary atoms are recurrently updated to adapt them to the specific seismic data.In the dictionary domain,large coefficients represent effective signals.Taking full advantage of this characteristic,the authors use several large coefficients from the last round of iteration as initial coefficients.In this way,the computational efficiency of the learning algorithm can be improved.The new algorithm is applied to synthetic and field seismic records and compared with the conventional K-SVD algorithm.The denoising results are satisfactory.It is shown that the new method can remove the random noise and protect the effective information at the same time.It is competitive in improving the signal-to-noise ratio of seismic records.

The ghost wave is developed well in deep water.Meanwhile,the seismic profile will be wrong when the ghost and the reflection merge or separate,and this situation infuences the oilfield exploration and development seriously.In order to analyze the characteristics of the seismic data acquisition environment and acquisition,the authors chose the wavelet method to remove the ghost wave by Echos (software of seismic data processing)processing platform.According to the acquisition parameter,the wavelet was designed for calculating the de-convolution factor which was applied to the actual seismic data.After the application,the notch points were compensated effectively.The results show that the ghost wave is effectively attenuated both on the shot and on stack profile,and the quality is effectively improved,which is benificial to the tectonic interpretation and reservoir research.

Regional geochemical data contain abundant geological information.The excavation of useful information from regional geochemical data is of important significance for the study of regional geology.In this paper,a model based on the self-organizing feature map and K-means algorithm is applied as a data excavation tool to discover hidden geological information from regional geochemical exploration data.For each data point,the raw data of each element is transformed by data normalization as the input value of the model.By means of SOM clustering and K-means clustering as the second step,the input data points can be divided into different groups,and then geological information can be acquired by analyzing the clustering results.Stream sediment survey data from southwest England is used as an example to test the performance of this model.The case study results demonstrate that:First,the clustering maps generated by the model agree well with the geological spatial distribution pattern.Accordingly,they can be used to predict the spatial distribution of geological bodies;Second,geological information is concealed in each cluster member.By analyzing and interpreting these geochemical characteristics, the geological information concealed in geochemical data can be discovered;Third,regional geochemical data excavation approach based on SOM network and K-means clustering is an effective geological information acquisition method,which can be used as a supplementary and strengthening way for conventional regional geology research.

When the gas yield is low, the gas velocity is not enough to take formation water out of the wellbore. As development time goes on, wellbore fluid will continue to increase, resulting in watering of gas well, which influences gas well productivity. In this paper, the mechanical model of the gas carrying water is established, which is used to calculate the gas flow in the gas carrying water dynamic state. According to the flow pattern characteristics of the upper, middle and lower sections of the wellbore, the three-section calculation method of gas phase flow is presented. The interpretation method is used to explain the log data of gas production profile in the low yield gas well. The interpretation result of the new method is more consistent with the actual production condition, which improves the accuracy of interpretation.

Grounded-wire source transient electromagnetic method is a hot research topic nowadays, and it is also very important to study all-time apparent resistivity of this method. In this paper, the author puts forward a fast and efficient calculation method of all-time apparent resistivity for grounded-wire source transient electromagnetic survey. This method can be used to calculate all-time apparent resistivity of multi-component quickly. The defination for all-time apparent resistivity can be achieved by using the translation scalability features of magnetic field characteristic curve in homogenous half space. The theoretical calculation results show that the apparent resistivity definition method does not require iterative with quicker speed and higher precision. Finally, a comparison was made for the resolution of electrical layer of horizontal magnetic field and vertical magnetic field based all-time apparent resistivity. The results indicate that the all-time apparent resistivity of the definition of two components has the same resolution. The results obtained by the authors establish the foundation for the multi-component interpretation technology of grounded-wire source transient electromagnetic method.

Traditional sectional view algorithm lacks accurate processing capability for such phenomena as pinch off, absence, and lenses of strata. The accuracy of the algorithm can hardly meet production requirements. To solve these problems, this paper proposes an auto-matching algorithm for building geological sectional view by stratigraphic distribution pattern. First, the project drilling data structure is built; then, based on the distribution of strata, the patterns of strata are defined and the section line growth policies and rules of each model are deduced. From left to right, from top to bottom, the sequence stratum pattern matching method is used; according to the problem as to which section line the stratum point belongs to is determined; finally, the section line sets of points are connected into the line, thus finishing map annotation and map decoration. The algorithm overcomes the problem of poor continuity existent in the traditional drilling adjacent connection method caused by the lack of consistency disadvantage. Stratum pattern auto-matching method achieves automatic section line growth and can wipe out stratum pinch off, stratum absence, stratum lens phenomenon accurately. Experiments show that the geological profile constructed algorithm can accurately and efficiently reflect the stratigraphic structure of the study area, and hence it is widely used in engineering production.

In BDS/GPS combination positioning, it is a very important step to select the satellite combination with the best spatial location. The traditional satellite selection algorithm involves a large number of matrix multiplication and inversion operations, so the calculation is large and the real-time is low. For the problem of rapidly fixing position, the authors, considering the positioning accuracy and real-time requirements, propose a new satellite selection algorithm, which combines the BP neural network and genetic algorithm, and uses the geometric dilution of precision (GDOP) as the basis of judging positioning accuracy. Through the comparison of GDOP and the running time acquired by this algorithm and the method of minimum geometric dilution of precision, it is found that the proposed algorithm can greatly reduce the computational complexity and ensure the positioning accuracy, thus exhibiting good real-time and feasibility.

The advantage of preferential upward continuation method lies in the fact that, when it is used for upward continuation, the low frequent signal is not attenuated excessively and it can retain as much information on geological features as possible, so it can accurately separate regional anomaly and local anomaly. However, in conventional methods both high and low frequent signals are attenuated simultaneously for upward continuation. The preferential upward continuation breaks up the restrictions of the conventional upward continuation. So the preferential upward continuation is a method that has the capability for self-adaptive qualitative enhancing and separating the aeromagnetic anomalies. In this paper, the aeromagnetic anomaly in Anshan-Benxi area was processed using the preferential upward continuation to realize the enhancement and separation of the anomaly in the deep source field, with a good effect obtained. Furthermore, the authors studied 3D inversion of typical Xianshan iron ore deposit and inferred the distribution of underground lithologic boundaries and the spatial morphology of the Xianshan iron ore deposit. The results provide an important reference for the qualitative interpretation of the aeromagnetic anomaly.

Geochemical distribution characteristics of 26 geochemical indexes were studied based on the geochemical survey of submarine sediments and seawater in Qiansan Island,Lianyungang,Jiangsu Province.The results show that the evaluating results of most indexes are well-distributed and close to corresponding background values,and the quality of submarine sediments and seawater is good;nevertheless,a few locations of the sea area exhibit relatively high evaluating values of different indexes,some of them have the potential environmental risk,and a few of the heavy metals exceed the environmental standards. On such a basis,3 risky areas (blocks or locations) and some potential risky locations were preliminarily delineated,and risky indexes such as As and Pb and some other potential risky indexes containing Cd,Ba,MnO were successfully determined.The qualities of the sediments in this area are classified into 3 levels,i.e.,clear level,sub-clear level and weakly contaminated level.The original source and evolutionary trends of some risky and potential risky indexes such as As,Pb and Ba are tentatively discussed with the purpose of providing some preliminary models or recommended plans for prompting the future construction and other activities in the coastal area of Jiangsu Province.

Castanea mollissima Blume is a low cost and high efficiency economic tree species; nevertheless, due to the regional differences, its quality is very different. The natural condition of the Jizhou Mountain area in Tianjin is suitable for the planting of Castanea mollissima Blume. In this paper, Castanea mollissima Blume in the main producing areas of Tianjin was studied from the chemical composition of Castanea mollissima Blume quality and site geological background. The results show that the average total flavonoids of Castanea mollissima Blume in Tianjin is 0.75 g/100g, the average total flavonoids is 8.11 g/100g, the average water content is 48.78%, the average total sugar is 11.53%, the average protein is 8.80 g/100g, and the average vitamin C is 15.18 mg/100g. N, K, and P, Mg, Ca, S, which belong to a large amount of nutrient elements in the soil, are the highest in the fruits of Castanea mollissima Blume. The producing area of Castanea mollissima Blume mainareas is mainly the Chuanlinggou Formation of the Changcheng System, with the lithology being dark shale silty shale. The values of SiO₂, K, Corg, N, Fe, B, Mn,, Ca, and pH are very suitable for the growth and fruit quality of Castanea mollissima Blume.

In the disaster geological problems such as shallow ground fissure etc. the demand for fine detection has been increasing in recent years. The first-break velocity tomography technique can provide a high accuracy of the vertical and horizontal anomalies of the shallow velocity field, and provide the basis for identifying the disaster geological phenomena such as ground fissures etc. In general, under certain conditions of acquisition parameters the accuracy of inversion imaging is limited by the algorithm, the grid type and the scale of the grid. Therefore, in order to improve the accuracy of the calculation and keep the grid type unchanged, the inversion of the grid need to be increased. On the basis of the improved algorithm, the effect of incremental and non-deceleration and high precision can be realized. In this paper, OpenMP-based stand-alone multi-core parallel technology is used, and the first-break tomography parallel algorithm is implemented. In the forward part, the improved traveltime linear interpolation method is used. The method of column calculation is used, and the method of line calculation is also used. In this case, the rays of each direction are taken into account, so that the minimum traveltime is obtained. In the inversion section, the LSQR method and the regularization technique are used. The results of theoretical and practical data test show that the convergence rate is fast and the inversion result is better. At the same time, compared with the conventional serial algorithm, the speed and efficiency of the algorithm are greatly improved under the condition of added sampling and reduced grid scale. Compared with commercial software,the change of computing efficiency is not obvious, but the accuracy and distinguishability of inversion results are better.

There are a lot of successful examples in coal mining working face internal probe of concealed structure for Radio wave perspective technique,but less research on the resolution and limitation of the method for the collapsing column probe was done.In order to illustrate the reliability and limitation of the method detecting the collapse column,numerical simulation and practical perspective instances are discussed from two aspects, numerical simulation method are adopted to simulate the collapse response in working face and the forward date was carried out on the inversion, The radio wave perspective method for isolation of single or multiple collapse column has a high degree of differentiation, the inversion position matches the reality highly, actual engineering example proved that the conclusion of numerical simulation,for collapse columns which transverse position differ little,the distinguish ability decline,resolution enhancement is limited by the construction method.