The continuous acquisition of dissolved methane concentration data in the deep sea has important scientific significance and practical application value for dynamic monitoring of marine environment and methane diffusion in gas hydrates development. This paper introduces key technologies of electrochemical in-situ long-term monitoring technology for deep sea methane in detail, which include the technical ideas of "seawater degassing, quantitative injection of gas samples, and high-precision electrochemical detection", the technical method of "sea water circulation controlled by supercharged drainage system, decompressed steady flow, gas-liquid separation, and improvement of high precision detection technology for hydrocarbon components". Based on the long-term monitoring experiment data obtained from bottom water in Jiaozhou Bay during 94 days, the authors studied and evaluated the technical performance, data quality and geological effect of the in-situ sensors. Some conclusions have been reached: (1) In-situ sensor has an index range of 0.01~10 000 nmol/L and sensitivity reaches 0.01 nmol/L. It has good stability and selectivity for the detection of hydrocarbon components; (2) The range of dissolved methane in the monitoring area is 19.01~106.87 nmol/L, the normal methane background is 32.41 nmol/L, and the local anomalous methane background is 80.60 nmol/L. These data show that abnormality is related to sewage discharge and seawater pollution; (3) The results of measured methane data are consistent with those obtained from previous investigation and study of seawater environment in Jiaozhou Bay, which proves that the measured data are objective and scientific; (4) The sea trial monitoring results show that the in-situ sensor is reliable in testing, reasonable in structure design and scientific in design ideas, and it basically has the capability for acquiring seawater methane concentration data in marine scientific investigation. It has practical application value and scientific significance in the dynamic monitoring of methane diffusion and long-term monitoring of deep sea methane concentration during the development of marine gas hydrate in the future.

Longmen fault zone is one of the most famous orogenic belts and seismic zones in the continental crust of China. In order to study the deep structure of Longmen thrust nappe belt and its relationship with the eastward escaping of material in the Tibetan Plateau, the authors completed four magnetotellurics profiles across the West Qinling orogenic belt, Songpan-Garze fold belt and the Sichuan basin, which included 80 broad-band magnetotellurics stations and 16 long-period stations. The electrical model diagram was obtained through two-dimensional and three-dimensional inversion. The model indicates that the Longmen Mountain fault zone is basically coincided with the electrical gradient zone in the depth less than 30 km. It means that the Longmen fault zone is a fault zone which is deep in the middle of the crust. Above the depth of 20 km, the distribution characteristics of the electrical structure in Songpan-Garze fold belt are complex and of low-conductivity, which is related to the complex surface structure. Below 20 km, the low conductivity is similar to that of the Longmen fault zone. It is inferred that high resistivity may be a reflection of the basement of the Sichuan basin, indicating that the Songpan-Garze fold belt pushed over Sichuan basin bounded by Longmen fault zone. It is concluded that the material migration under the Tibetan Plateau happened under the Songpan-Garze fold belt. The material escaped northeastward from Lixian to Dangchang, at the depth of 18km to 30km with the partial-melting.

The Yinchuan plain is a region of active faults which are closely related to earthquake disasters. The study of active faults in the Yinchuan plain is of great significance for the development of the city. In this paper, the gravity anomaly characteristics of the area are analyzed and the fracture system is divided by the method of gravity boundary recognition based on the re-processing of 1∶200 000 Bouguergravity anomaly data of the Yinchuan plain. The quantitative inversion of the 83503 line section of the study area is carried out by using the method of fracture parametric graph, the Euler homogeneous equation, the optimal inversion and the 2.5D inversion. The inversion results and the seismic interpretation are coincident. Using the existing gravity data, the authors probed into the method of interpreting the plane fracture system and the quantitative inversion of the section fracture and, as a result, some new understanding was obtained such as the north extension of the Yinchuan fault and westward migration of a part of Yellow River fault. The result provides a new reference for the research on active faults.

In order to get to know the relationship between regional lead-zinc geochemical anomalies and mineralization, metallogenic regularity and ore-forming factors, the authors carried out 1∶10 000 geological survey, soil-rock geochemical measurement and IP survey. Based on comprehensive study, it is found that four geophysical IP anomalies are similar to geochemical soil anomalies in shape and geographical position and both have strong reflection. With the length of 760 m,average thickness of 1.40 m, 3.03% lead and 2.78% zinc, an ore-bearing vein was detected by shallow trenching at the center of the anomaly, which shows good metallogenic conditions, rich minerals and great potential of deep prospecting in Jiulongshan survey area.

In this study, the moving average method was used to reprocess the 1∶200,000 stream sediments data from seven sheets in Wutaishan-Hengshan area. In combination with the 1∶200,000 gravity data and 1∶50,000 aeromagnetic data obtained in this area, the authors found that the comprehensive anomalies are in good agreement with the deposits related to the Yanshanian rock mass. Choosing elements such as Au, Ag, Cu, Pb, Zn anomalies and high-magnetic and low-gravity anomalies as the prediction criteria, the authors predicted a total of 13 polymetallic ore prospective areas related to the mineralization of rock masses in the study area. According to available data, there are 9 NW-trending fault structural zones in this area. The intrusive position of the rock mass is controlled by the intersection of the NW-trending fault and the NE-trending fault. Most of the known rock masses and the 11 prospective areas predicted by this paper are distributed in the fault structural belt, forming multiple tectonic magmatic zones. The polymetallic ore deposit is inextricably linked with Yanshanian rock mass.

In the northern part of Helan Mountain, the structure is active and strong, the mid-acid intrusive rock is well developed, and the metallogenic exploration is favorable. The mineral prospecting indicators have rich information, suggesting a good gold and tungsten prospecting area. This area is characterized by arid low mountain and hilly desert geochemical landscape. The 1∶200,000 river sediment measurement work completed by the previous workers in this area is limited by unfavorable conditions such as sampling media, sample grain level, test equipment, and analysis methods, making the useful prospecting information weak. In this study, the chemical exploration work used an irregular network of 1∶50,000 rock debris measurement, -4 to +20 sampling grain meshes, and a C-layer working technical method in sampling layer, which led to the delineation of 30 comprehensive anomalies. There are 9 anomalies of Au, W, As, and Sn in the distribution area of the metamorphic rock in the second rock group in Yanqun area of Helan Mountain. Through anomaly verification, 14 new ore spots and mineralization spots were discovered, and 3 of them were identified. , In addition, 9 mineral target areas were selected through optimization. Thus, good ore prospecting results were obtained. For the first time, laminated scheelite was found in the silicified shallower part of the second group of Helan Mountain Rock Group. The significance of this discovery lies not only in the discovery of ore spots in the investigation area but also in the study of formation environment of known stratabound scheelite ore deposits in China. The orebodies were produced in the meso-deep horizons of metamorphic rocks and are characterized by stratiform or stratoid forms, which is very rare in the world.

The authors applied the wide field electromagnetic method to conducting work in Mesoproterozoic carbonatite nappe area and achieved good result. It is for the first time that Beipiao source formation was discovered below the carbonatite nappe, which was further proved by well cores. It shows low resistance in comparison with things of its adjacent layers. The actual electronic resistance of underground electric body was also obtained. These discoveries have enriched the exploration strata of the east Yanliao subsiding belt and expanded one Mesoproterozoic exploration stratum to two exploration strata, i.e., the Mesoproterozoic black carbonate stratum and mudstone stratum.

To study the effectiveness of CO₂ gas measurement method in the exploration for concealed mineral deposits in hilly areas,the authors carried out pilot study and area study by employing CO₂ gas measurement with rapid gas analytical techniques at Jinmei ore block and Lishuping ore block of Huangjindong mining area,respectively. The results indicate that CO₂ gas measurement method can discover the information around deeply buried mineral deposits and deep-seated structures. Having delineated three prospecting target areas for Lishuping ore block, it is proved to have important practical significance and can accumulate data and experience for concealed mineral exploration in covered areas.

Statistics show that, during the 12th Five-Year Plan period,1747 wells were drilled for drought-resistant water prospecting in Guangxi. The electric method had a 75% success rate in finding water in karst area and 10% in clastic rock area, showing remarkable difference. The difference in lithology and hydrogeological conditions between the clastic rock and the karst rock is the main internal cause of the great difference in the effects of the electric method. The stratigraphic lithology of the clastic rock area is mainly mud rock and conglomerate rock, among which, the siltstone and fine sandstone in the mud rock and sand rock have poor water content conditions. This kind of rock is a low-reisitivity rock ,which is an interference layer of electric water exploration rather than a target stratum. Coarse sandstone and conglomerate in sand rocks belong to hard and brittle rocks, which are likely to form fissures and water. This kind of rock belongs to high resistivity stratum,which is the main target bed for electric water exploration. In the clastic rock area, the upper part of the layer with significant changes in the lithofacies is developed by fracture propagation and is rich in groundwater. Based on the case analysis, this paper summarizes the experience of electrical water prospecting in clastic rock mountains, and provides a reference for the future electrical water prospecting in clastic rock areas.

Well-developed faults and diversified lithology constitute the features of Sanlutian well field, and the drilling results reveal that gas hydrate mainly occurs in the fractures of reservoirs. Therefore, the acoustic image logging data are used specifically to study the structural fractures from borehole walls of gas-hydrate drilling holes in Sanlutian well field. In this paper, the response characteristics of fractures in acoustic image logging were confirmed and the linear density, dip angle and dip direction of fractures were discussed. Some conclusions have been reached: ① Fractures are developed in the borehole walls of gas-hydrate drilling holes. In these fractures, high-angle fractures are dominant, followed by low-angle fractures, and the vertical and horizontal fractures are rare. ②The main strike of fractures is basically consistent with the fault strike or oblique-crossing at small angles. The distribution of fractures is controlled distinctly by faults. ③It is unfavorable for the assembly of hydrocarbon gases as the fractures of the study area are dominated by high-angle fractures, which is one of the possible reasons why gas-hydrate is rare.

Ground penetrating radar (GPR) is a high-precision geophysical exploration method whose main purpose is to invert the physical properties of underground structures.In this paper,an improved particle swarm optimization (PSO) is used to solve GPR inverse problem.The inversion takes the signal mean square error as the objective function and uses the finite-difference time-domain method to do forward modeling.In addition,the inversion accuracy is improved by the amplitude compensation of the forward result.Compared with the results based on classical particle swarm optimization inversion method,the algorithm shows considerable improvement in accuracy and efficiency.An analysis of the one-dimensional inversion results of multi-layer simulation data shows that the inversion method is effective for multi-parameter inversion and has good noise immunity.

Seismic anisotropy characterized by velocity anisotropy will inevitably affect the kinematic characteristics of underground seismic waves.Ignoring the anisotropy of the media will result in inaccurate velocity extraction and thus affect the imaging of target region.In view of such a situation,the authors carried out a study of anisotropy in this paper.According to the first-order velocity stress equation in VTI media,the authors obtained the cross-correlation imaging condition based on wavefield separation which used Poynting vector.Then the authors applied it to complex VTI media,and demonstrated the validity and superiority of the algorithm by numerical experiments.This method produces better images with less noise even for inaccurate migration velocities.

In comparison with the routine ray tomographic velocity model construction,the tomographic velocity model construction based on undulation theory considers the belt limitation property of the wave,and hence it has higher inversion resolution.The core of the undulation theory tomography lies in the calculation of the wave route (finite frequency kernel function).This paper introduces in detail a method for calculation of finite frequency kernel function based on Gassian beam operator,analyzes the effect of the initial width and the emergence angle interval of the Gassian beam on the calculation precision.To overcome the defect of the relatively large error at the near-source place of the Gassian beam,the authors put forward improved beam parameters so as to raise the near-source precision.This paper also analyzes in detail the effect of initial beam width and angle interval on the improved Gassian beam and the focussing characteristics of the improved Gassian beam.Digital calculation example has verified the feasibility of this method in calculation of finite frequency kernel function.Its calculation efficiency is relatively high and it can process kernel function of the inflection wave.

The 3D orebody surface modeling method based on contours is the main method of orebody modeling; nevertheless, in practical application, the traditional modeling method has shortcomings, which have been improved with the method in this paper. In general, contour lines of these methods are used to reconstruct the surface model by artificial selection of two contour lines, but it is difficult to grasp the overall trend of the orebody as a whole, and the shape of the three dimensional orebodies is relatively coarse. When researchers deal with the problem of branch, it is very tedious to add the branch point in that it takes a lot of manpower and time, and it is difficult to guarantee the correct result. The surface model of the orebody exhibits a lot of degenerated triangles, even in the situation that the surfaces of the orebodies are self-intersected or overlapped, hence the geometric quality of the model is so poor that it influences subsequent visualization and model calculation. The trend line for a group of contours is introduced, and it can also be edited. Then the encryption method for refining the intermediate contours so as to achieve the control of the orebody shape is used. Through projection, the shortest distance between closed contours is calculated, and branch points are automatically added. The constrained triangulation with holes is used to achieve the building of branch automatically, which greatly saves human resources and ensures the accuracy of branch of orebody. According to the problem of poor geometric quality of the initial 3D orebody surface model, the quality control to achieve the reconstruction of the surface model is introduced, which ensures the model quality and subsequent calculation. These improvements have achieved good results in practical application.

This paper introduces the research, development and integration of an unmanned helicopter aeromagnetic survey system. The system uses an unmanned helicopter as flying platform to carry out the high-precision aeromagnetic equipment. As all know, the unmanned helicopter doesn't need a runway to take off and land, and has the ability to self-navigate according to designed lines and to work at night. Thus, it can get a higher efficiency at a lower costing. An aeromagnetic compensation flight whose accuracy was 0.046 9 nT and several survey flights have been accomplished. Compared with the previous aeromagnetic survey in the same area, the characteristics of the geomagnetic field are basically alike, which validates the effectiveness of the unmanned helicopter aeromagnetic system. The unmanned helicopter aeromagnetic anomaly map is more detailed because of the different parameters such as scale and instrumental accuracy and sampling rate between the two systems. This unmanned helicopter aeromagnetic survey system provides an effective and flexible means for large scale, high-precision and small area aeromagnetic survey.

The ground-airborne transient electromagnetic method combines the principle and observation mode of ground and air transient electromagnetic survey, places the emission source on the surface, and uses the aircraft to receive the response signal in the air. Therefore, the ground-airborne transient electromagnetic method has the advantages of large sounding depth of the ground device, high signal-to-noise ratio and high efficiency of aviation equipment acquisition. Previous studies have focused on a single source of radiation, ignoring the advantages of multi-radiation field sources in exploration depth and signal-to-noise ratio. Therefore, it is necessary to study the data interpretation method applicable to the ground device of the multi-radiation field source. After solving the problem of the ground-airborne transient electromagnetic forward modeling and on the basis of the principle of Occam inversion, the authors studied one-dimensional inversion of multi-source ground-airborne transient electromagnetic survey. First of all, the important problem is the construction of objective function, and the objective function is constituted by the misfit and model roughness by introducing the Lagrange multiplier. Secondly, the problem of the construction of the sensitivity matrix is solved. The model calculation results show 1D Inversion of Multi-source Ground-airborne Transient Electromagnetic Method is effective, which can provide a good foundation and fine interpretation for three-dimensional inversion and fine interpretation. Through the inversion calculation of the typical model, it can be seen from the comparative study of its theoretical model and inversion results that the Occam inversion method can be applied to the Multi-source Ground-airborne Transient Electromagnetic Method, and adds a new approach to the interpretation of the Multi-source Ground-airborne TEM.

Surface-borehole TEM method has achieved good results in exploration in Canada and Australia. Due to the lack of complete technology from equipment to data processing and interpretation, the method has not been widely used in China. The authors developed the surface-borehole TEM instrument and, at the same time, systematically studied the determination of the three component coordinates of the surface-borehole TEM, the measurement of the deviation of the probe angle, the correction of the three components, and the analysis and calculation of the orientation and distance of the target body, which achieved good application results in actual measurement.

This paper introduces a kind of calculation method for characteristic parameters of single element anomaly in the geochemical reconnaissance. After the determination of lower limit of single element anomaly, the data layer of sampling point position is established, the single element anomaly map is prepared, area-to-point spatial analysis is conducted between the area layer of single element anomaly and the data layer of point position, and the spatial information on anomaly number, anomaly area and perimeter field in the area of single element anomaly is superimposed on the data layer of point position. The application software is programmed to calculate the characteristic parameter of single element anomaly.

Aero geophysical survey regions maps reflect the information of aero geophysical survey work in the past, and also provide references for survey data collection and survey work planning. In order to fulfill the large demand of industrial and social users for multi-scale and cross-regional aero geophysical survey regions maps, the authors employed National Aero Geophysical Metadata Database established by AGRS to carry out studies of batch creating maps. According to the technical route of “graphic standards stored in data dictionary, drawing style managed by template files, dynamic drawing elements by user parameters”, the technique of batch customizing aero geophysical survey regions maps is realized. The technology achieved good application results in the socialized service of aero geophysical survey data and the project deployment and implementation of “Aero geophysical surveys in key ore-forming areas such as Qinling and Tianshan”.

Shear wave velocity plays an important role in seismic modeling,AVO analysis and fluid identification.However,realistic well logging data lack shear wave information,so shear wave velocity prediction becomes concentrated on rock physics research.Integrating K-T model and Pride model,the authors propose in this papera new rock physics model which is used to calculate dry rock moduli.The new rock physics model proposed in this paper integrates effects of pore shape and diagenesis to bulk modulus and shear modulus of dry rock,so it is more rational and its accuracy is high.At the same time,in combination with Gassmann theory,P-wave velocity and S-wave velocity model of fluid saturated rock is established.The model is applied to S-wave velocity predicting of measured data in lab and realistic well logging data.The predicted results demonstrate that S-wave velocity prediction based on the new rock physics model proposed in this paper is effective.

In order to quantitatively evaluate thin reservoir of high speed surrounding rock shielding by seismic data after time frequency conversion,the generalized S transform is applied to processing for target seismic,and then ascertain the time and frequency seismic recognition extent for thin reservoir.Combined with basic sand parameter,frequency spectral analysis,and time frequency characteristics of thin reservoir,carry out single frequency seismic optimization,and extract frequency gradient attribute to qualitatively analysis the plane distribution of sedimentary reservoir.Construct the mathematical relationship between drilling data and frequency gradient to finish quantitatively evaluation for thin reservoir.The practical example in Middle East shows that the multi-frequency interpretation techniques based on generalized S transform has a good application result for thin reservoir of high speed surrounding rock shielding,and the reservoir prediction accuracy was improved.It provides a set of technical ideas for quantitative reservoir evaluation by seismic data and has broad application prospects.

Ghost attenuation,the key step of broadband processing,is a very important step in data-processing of deep towing flat streamer.Therefore,this paper analyzes the features of deep towing flat cable data,derives time distance curve equation of ghost and,on such a basis,introduces the basic principle of the linear least square inversion in Radon domain method for ghost attenuation.First,no ghost data is obtained by the least square method in Radon domain,then the primary wave operator is used in inverse transform,so as to realize the attenuation of ghost.The processing effect of model and actual data shows that,after ghost attenuation,the frequency notches of deep towing flat cable data can be compensated,and the effective frequency bandwidth can be broadened,thus achieving the effect of broadband processing.

As is known,the exploration of multi-measures reservoir will cause a lot of time-lapsed seismic matching processing problems,such as time,phase,frequency,and energy difference accumulation caused by complex changes in multi-measures reservoir production.A new method called time-lapsed seismic matching processing technology based on multi-marker horizon is proposed in the paper.By using the stable non-reservoir or undeveloped reservoir at the top and emnploying the internal part and the bottom of the multi-measures reservoir as the reference marker horizon,the time-lapsed seismic matching processing for multi-reservoir is realized,which can effectively eliminate false appearance of lower reservoir time-lapsed seismic difference caused by upper reservoir development.It was applied effectively in X oil field of South China Sea.

The surface wave in the real seismic data can be used to invert near surface shear velocity.If the trace interval is large and the spatial sampling rate is not enough,there will be spatial aliasing.This can not only decrease the signal-to-noise ratio of frequency-velocity spectra but also affect the accuracy of dispersion curves and the result of inversion.So it is necessary to do the interpolation of surface wave.This paper presents a seismic surface wave interpolation method based on optimistic wavelet basis.The optimistic wavelet basis bior6.8 which is suitable for interpolation processing can be selected among many wavelet bases commonly used in seismic data processing through the theoretical analysis and the comparison of experimental error.The use of optimistic wavelet basis bior6.8 will increase the accuracy of interpolation.Because the events of surface wave are linear and the slopes of them are larger,this paper uses the linear normal moveout to level the events of surface wave firstly,then carries out the wavelet transform interpolation,and finally uses the inverse linear normal moveout to recover the surface wave.The effectiveness of the proposed method is verified by the interpolation result of theoretical model and real seismic data.After the interpolation,the waveform of the interpolated surface wave records is well recovered. It can improve the signal-to-noise ratio of frequency-velocity spectra,and solve the aliasing problem effectively caused by the undersampling of the surface wave data.

The accuracy of seismic wave traveltimes directly affects the reliability of research results in such fields as seismic inversion,pre-stack migration imaging and tomography.Therefore,it is of great significance to study the improvement of the accuracy of seismic wave traveltimes.Based on the double grid technology,this paper comes up with a fast marching method (FMM) based on the grid-various finite-difference scheme to calculate the traveltimes of seismic wave.It analyzes the advantages and applicability of the grid-various finite-difference FMM by the forward simulation of uniform model as well as the existence of high-speed anomalous body model,Marmousi model.The results show that the corner points need to be included in the calculation when the traveltimes are calculated by using Eikonal equation so as to reduce the error.Under the background of uniform model,the grid-variable finite-difference FMM has the same advantages as the double grid FMM.Nevertheless,under the background of the existence of high-speed anomalous body model,the double grid FMM may violate the law of wavefront expansion to cause a greater error.The grid-variable finite-difference FMM does not have such a problem,and its advantage is remarkable.Therefore,this method is an effective way to improve the accuracy and efficiency of traveltime calculation,which not only enhances the applicability of the FMM but also expands the application range of grid-various technology.

The static test of gravimeter is a necessary step for the performance inspection of gravity before the beginning of gravity exploration. Because the principle of data processing in static test is too simple that no one attaches importance to it. So there is no standard and systematic way to deal with it. Nevertheless, its computing process is very complex. When a beginner faces a large number of data and multiple goals, he is prone to neglect one of them or to repeat the calculation. This causes the waste of time. Excel has powerful functions of mathematical calculation and graphic display, and is widely used and easy to operate. Excel can process original observation records of static test of CG-5 gravimeter, quickly get a static test data table and zero point drift curve and its fitting line diagram. At the same time, parameters such as the deviation of zero point drift curve and the straight line as well as the average zero point drift rate are calculated. The scatter plot trend line function of Excel also improves the calculation method and accuracy of static zero shift correction parameter DRIFT. This static test data processing method is quick, accurate and intuitive.

The landslide in southwest China has caused serious casualties and huge economic and property losses. It is very important to determine the type and scale of landslide. First, this paper introduced the principle and data processing method of high density resistivity method. Second, we summarized the different classification methods and physical characteristics of the landslide. Finally, through the comprehensive analysis of more than 20 landslide survey data obtained by high density resistivity method, it is held that the apparent resistivity characteristics of the different types of landslide are different obviously. With practical examples, this paper mainly deals with three abnormal characteristics of high density resistivity method detection, i.e., the soil landslide, rock landslide and broken rock landslide. It is proved that the high-density electrical method can deduce the type and material composition of the slope from the abnormal characteristics of the apparent resistivity, and provide guidance and demonstration for the investigation of the landslide body and the later management and drilling construction.