In Han-Xing plain of Hebei Province, the authors used multistage classification principles of the form-causes-lithology to study the Quaternary geomorphologic unit. The geomorphology of the study area was divided into two primary units, nine secondary units and twenty-six grade three units. By using the multi-target geochemical data in Hebei Province, with SiO₂, Al₂O₃, Fe₂O₃, w(Na)/w(Rb), homogenization accumulation of Rb, U and Ga as the indices for Quaternary geomorphologic geological unit division, the division of Han-Xing plain in Hebei Province was conducted. Research proves that these geochemical indicators have an obvious effect in dividing ancient river channel, Zhanghe alluvial proluvial fan, even the stage of Hutuo River fan and the zoning of flood plain area. There is a clear proof in identifying Ningjinbo, Daliuze and Yongnianwa depositional depressions. The experiment based on the element geochemistry for studying geological units has been successfully conducted.

On the basis of 1:50000 stream sediment -10-+60 mesh survey in Alpine Lake Hill Landscape of Xainza City, Tibet, this paper discussed the characteristics of stream sediment element content and combinations, element background values in ophiolite zone,element anomalies and their prospecting significance in ophiolite and sedimentary zone. The results show that, in the sedimentary zone, most elements are significantly enriched,except for such elements as Cr, Co, Ni and Hg. The characteristics of element combinations better reflect mineralization. On the contrary, in the ophiolite zone, the elements of Cr, Co and Ni show very high relationship, but the element combinations fail to reflect good mineralization; as for the elements of Au, Co, Cu, F, Zn, the positive anomalies are not obvious in the ophiolite zone. In this study, one class A anomaly and eleven class B anomalies were delineated, and two new gold mineralization spots were discovered. The anomalies are good indications of geological structures and mineral resources. Under the similar conditions of geological landscape, this method is obviously significant in revealing element geochemical characteristics and guiding prospecting.

This paper describes the application of the controlled source audio frequency magnetotelluric sounding (CSAMT)in search for deep geological structure in Zoujiashan area,Xiangshan volcanic basin. The results show that the CSAMT method divided the boundary of different groups and the basement interface,identified three faults,revealed the morphological characteristics of underground rock and structure successively above the depth of 2000 m. The boundaries of different groups divided by CSAMT method agree well with the actual locations, as shown by the comparison with drilling information. The results show that the CSAMT method is effective in the deep geological information detection in this area.

Uranium mineralization is closely associated with Mesozoic-Cenozoic continental red beds in time and space, and regional uranium mineralization was developed during the formation of red beds. Existing red beds can reflect indirectly uranium deposit under better or poor conditions, and hence red beds can act as an indicator of uranium mineralization. The methods of audio magnetotelluric survey (AMT) and soil radon measurement are introduced in the paper. Based on geological data and resistivity characteristics of rocks, the authors ascertained the thickness, occurrence and contact relations of the red layer and the deep characteristics of the concealed fault roughly by using AMT data. Through soil radon measurement, the reliability of the inferred fault is improved and uranium mineralization information is indicated. A comparison with the drilling data shows that the inferred results can reflect basically actual geological situation and play a guiding role in uranium ore-searching in red basin area.

Through the implementation of 1:5000 soil geochemical survey, the authors determined the indicator elements of Au, Cu, Pb, As and Zn. By choosing the traditional statistical method, the authors calculated the threshold of each element in the soil, i.e., Au is 6×10^-9, Cu is 30×10^-6, Pb is 40×10^-6, Zn is 150×10^-6, and As is 50×10^-6. On such a basis, a group of valuable geochemical anomaly areas were detected. The prospecting potential of the geochemical anomaly area were analyzed in detail. In combination with favorable ore-controlling factors such as strata, lithology and structure, the authors synthetically evaluated main ore-forming elements and the abnormal element combination, and then selected three prospecting target areas. In No.Ⅰanomaly target zone, Au, As, Cu and Pb have good spatial assembly; M1-M7 gold-bearing quartz vein bodies were detected, and No. I, No. Ⅱorebodies were delineated in No. Ⅲ anomaly target area in the western part, and anomalies of Au, As and Zn are well superimposed upon each other. M11, M12, M13 gold-bearing quartz vein bodies were found, and No. Ⅲ orebody was delineated by verification engineering. Through the drilling and trenching engineering verification of the anomaly, the anomaly locations, sizes and trends were determined, which accord well with the newly found orebodies (ore spots), suggesting that soil geochemical survey is effective in the study area and hence deserves promotion in the neighboring areas.

The study of fine particle total measurement over the Huaniushan Pb-Zn deposit of Gansu Province was conducted. The authors have revealed that major ore-forming elements Pb and Zn show obvious background-anomaly contrast and strong concentration coefficient; in addition, they have positive correlation with Ag, Sb, As, Au, Hg and Cu. There are Pb-Zn-Ag-Au-Sb-As-Cu-Hg geochemical anomalies delineated by this method and the anomalies are located right over the known orebodies, indicating that the geochemical exploration method can be used to effectively locate reliable prospecting targets in Gobi desert terrain.

The application of geophysical and geochemical anomaly characteristics and the integrated study of the evaluation criteria in the Qinling gold and lead-zinc polymetallic ore district can play the role of mutual supplement and mutual verification. Based on geochemical anomaly characteristics and geological environment of the exploration area, the authors hold that the major ore-forming elements are Au and Ag, with the existence of the polymetallic element superimposed anomalies of Au, Ag, As, Hg, Cu, Pb, Zn, W and Mo. The magnetism is relatively low, and the ore-bearing structural alteration zone has relatively high polarizability and low apparent resistivity. Nevertheless, in the geological section, the orebodies mostly exhibit high resistivity and highe polarization. Based on characteristics of ore-related and barren anomalies, the authors established geophysical and geochemical ore-prospecting criteria for the exploration area. It is proved that the integrated method can yield better ore-prospecting effects in the search for structural altered rock type gold deposits in Qinling region.

Based on 1:25000 stream sediment survey results of the Qagan Us gold deposit in Hejing County of Xinjiang and summarization of the distribution of elements, the authors integrated favorable combinations of the elements and delineated the anomalies. Then in the anomaly the authors found K3, K4 orebodies through comprehensive geological prospecting. On the basis of an analysis of the axial primary halo zoning of K3 orebody, the authors hold that K3 orebody still has good extension below 160 m.

This paper describes the data acquisition and data processing method for EH-4 electromagnetic imaging system and its detection of the deep extension of the structure. In the Juzhugou ore district, the drilling verification shows that EH-4 electromagnetic imaging can clearly distinguish the mineralized alteration structural belt and the surrounding rock, The mineralization anomaly is caused by the vein, whose resistivity is about 1500~2500Ω·m. Deposit case study shows that EH-4 continuous conductivity imaging measurement of the apparent resistivity of two-dimensional-depth profile can clearly reflect different underground geological structures of fine resistivity, and can interpret spatial distribution of mine tectonic belt and mineralization anomalies. Practice has proved that EH-4 technology is effective in the detection of deep structure extension.

The ground microseismic weak signal curvelet coefficient has a small amplitude after curvelet transform;this part of the weak signal will be covered by the noise of curvelet coefficient.The conventional threshold function fails to differentiate effective weak signal from ineffective ones,and hence the effective weak signal will be removed as noise.For the ground weak signal in microseismic data processing,the weak signal should be tackled with less damage in noise suppression.In this paper,the authors put forward a compensation threshold algorithm on the basis of the conventional threshold function.The authors add a new threshold between the weak signal and noise,so that it can compensate the damaged weak signal overlapped with the noise of curvelet coefficient.Model test and actual data processing show that compensation threshold function algorithm is better in suppressing random and coherent noise of the microseismic data than the conventional threshold function.It can also improve the signal-to-noise ratio of data and achieve the purpose of weak signal detection.

The explosive effect of vibroseis is directly related to the quality of acquired data by vibroseis.Usually combined excitation of means is used to ensure energy.This method will theoretically influence the effect of seismic data.The reflection time difference between the combinations lead to out-phase stacking,which affects the geological imaging precision.Through theoretical calculation,modeling and real seismic data analysis,the authors found the influence regularity of time-space domain.With less number of vibroseis area array,combined with high folds and geophone array,we can effectively reduce the influence.This method also improves the efficiency and reduce cost,is easier to implement in the complex surface area,and is more suitable for high precision acquisition.

Research on seabed classification and recognition is of great significance.The reflection intensity of sub-bottom profile data is mainly related to the seabed sediment types.In this paper,the authors selected a sub-bottom profile data in the South China Sea as the study object,drew the contour map by extracting the RMS amplitude of the sub-bottom profile data and analyzed the macroscopic characteristics of the seabed sediment in the study area.Compared with deep sea video recording,the method of seabed amplitude characteristic attributes of sub-bottom profile data is suitable for direct seabed analysis.

It can be seen that electrical resistivity imaging method, with high efficiency and multiple measuring lines, has shallow surveying depth limited by array length. The combination of arbitrary pole pitch sounding and telecontrol electrode array method placing two wires A, B and telecontrol electrode array at the ends of array can triple the conventional measurement length through data merging and inverting in the prospecting of crevasse geothermal resources in Hainan Island. It is suggested that further improvement and promotion of the method mentioned above is still needed, though it has already achieved good geological effect.

In order to study the effective detection depth of the wide field electromagnetic method (WFEM) under the condition of transition zone, the authors designed four geoelectrical models, i.e., homogenous half space, two layers section, three layers section and four layers section, with the skin depth-apparent resistivity curves obtained by forward calculation. Taking magnetotelluric sounding (MT) for reference, the authors made a comparative study of the detection depth of the wide field electromagnetic method and the controlled source audio magnetotelluric method (CSAMT) at the same transmit-receive distance. The results show that the wide field electromagnetic method can be measured in the transition zone and can get larger detection depth with the smaller transmit-receive distance.

In the practice of high-density electrical prospecting, geologists usually only use the parameters of resistivity anomalies to perform interpretation and deduction. However, under suitable geoelectric conditions, regular large amplitude negative potential difference can be observed. Based on theoretical analysis in combination with several engineering examples, the authors explain the high-density electrical potential difference of negative exploration process to determine the role of adjuvant.

As one of the most pivotal resources, coal cannot be replaced. The evaluation of coal properties plays an essential role in the development. The calculation of coal properties based on laboratory analysis is inefficient and expensive. In this paper, the authors have resolved this problem by establishing the relationship between logging parameters and coal properties. Natural gamma, time difference, density and three-lateral resistivity are treated as input, and values of moisture, ash, volatile matter and fixed carbon are chosen as output. By using 73-layer logging data to train, the authors constructed a model based on GRNN and LS-SVM to calculate coal qualities. Through testing 19-layer data, the authors have reached the conclusion that these two methods can be well used in practice. The GRNN can calculate the content of moisture, ash, volatile matter and fixed carbon more accurately than LS-SVM, with its mean square error lower than 1%.

Aircraft vibration has an effect on airborne gravity and gravity gradient measuring system.In order to have a full understanding of aircraft vibrational characteristics and provide some advices and references for instrument system ranges and physical design,the authors carried out a large amount of measurement and depth analysis of vibration characteristics of Y-12 and Cessna 208 aircraft.The results show that the vibration of aircraft floor is mainly caused by the engine,the propellers speed shows regular multiple frequency distribution in vibration energy,and its fundamental frequency of multiple frequency is expressed as fundamental frequency of propellers speed multiplied by the propeller vane.The vibration of the aircraft under flight conditions is the typical periodic vibration signal.

Dead time is a very important parameter of FD-3019γ logging instrument.This paper described the definition of dead time,introduced measurement,calculation and correction methods of dead time,explained the necessity of dead time correction by comparing revised data and calculated the errors of uranium content in the drill holes.

For MT two-dimensional inversion of polylines profile, researchers usually use a separate profile inversion for each measured line profile, or conduct profile inversion with the type of "polylines bending straightening". The former of segmented inversion can't make the inversion results stitch up perfectly due to the boundary effect, and the latter inversion results can not reflect the true length of the measured profile, so that both situations affect interpretation work. The authors thus propose an improved method for two-dimensional polylines MT inversion. Firstly, a measured profile orientation is chosen as the fixed orientation of the MT two-dimensional inversion (usually, it is the longest one), the distance Li between each points is calculated on the adjacent measured profiles and the inflection point nearby, then the coordinate of measured points is rotated in a distance Li. In this way, the measuring points will be normalized to the original fixed orientation of the measured line, with progressively analogy. Finally, the two-dimensional inversion can be conducted for the new profile data. Based on applying this improved method, the comparative analysis of forward and inversion in different polarization modes and the verification results of measured data, the authors hold that this method can effectively resolve the problem of the influence of the boundary effect in the stitching position of MT two-dimensional inversion and can also reflect the maximum possible extent of the true length of the measured profile, thus improving the reliability of the inversion results and helping later comprehensive interpretation.

Based on the gravity gradient transformation model experiments for different data length,the frequency singular points in the transformation expressions was found to be the error source by spectrum and anomaly distortion analysis.The transformation error will decrease and the result will be better as the frequency resolution improvement with the data length increasing.

In airborne magnetic survey,the fault structure has great influence on the formation of orebodies in this mining area.In order to identify the fault structure distribution of the study area,the authors tentatively applied the edge enhancement methods.This paper mainly introduces three edge enhancement methods,i.e.,the tilt-depth,the non-absolute value of total derivative and the Theta angle.Meanwhile,it discusses the effects of various edge enhancement methods in combination with the upward continuation method through examples.The results suggest that various edge enhancement methods can identify the location of the fault structure,and that the tilt-depth method has an advantage in determining the depth of the fault structure.The non-absolute value of total derivative method can emphasize some small exceptions,and can also determine the attitude of fault structure.Theta angle method is superior to the other edge enhancement methods,and it has a higher recognition accuracy.The study results show that the combination of the edge enhancement methods and the upward continuation method can embody the advantages of the aeromagnetic data used in comprehensive interpretation.

In order to evaluate the quality of the aeromagnetic survey data,it is usually used to measure the repeated lines flying,and calculate internal accord accuracy of them.For this purpose,the most important is to establish the corresponding measurement points on the measured line and repeated line.We use the minimum distance method to calculate them. and then get the result of the internal accord accuracy.

AVO analysis technology is an important means to analyze oil and gas fracture cave reservoir in the Upper Ordovician carbonate strata of the Halahatang oilfield,Tarim Basin.As previous work in this area by using the conventional processing seismic data for AVO analysis did not consider the effect of azimuthal angle factors,the accordance rate of hydrocarbon detection result was low and could not fully meet the high precision requirement of oilfield exploration and exploitation.Therefore,in this paper,in view of the influence of the anisotropy of fractures on the AVO analysis, the authors carried out the analysis of azimuthal AVO based on analyzing the azimuthal anisotropy of OVT gathers so as to weaken the effect of anisotropy on the AVO oil and gas. Practice shows that the application effect is very obvious in that it can effectively weaken the influence of fractured anisotropic characteristics that affects the results of prediction of oil and gas. The prediction accuracy is improved and provides a reliable basis for deploying the efficient well group in the developing block.

Compared with VTI qP-wave modeling,TTI qP-wave numerical simulation method which considers dip angle factor could be more accurate in describing the characteristics of wave-field propagation in real anisotropic media.Because of the rapid change of dip angle in TTI media,using the conventional acoustic approximated method may cause numerical instability.In this paper,the authors first derived the stable TTI second-order qP-wave equations by introducing an anisotropic control parameter to ensure the stability of qP-wave propagation.Then,the equivalent first-order stress-velocity forms were deduced through introducing the pseudo-velocity components of the wave-fields,and the corresponding PML boundary condition was given.Finally,the authors implemented accurate numerical simulation using the optimal rotated stagger-grid finite-difference (RSGFD) method.Numerical results demonstrate that TTI first-order qP-wave equations can describe the kinematics features of qP-wave effectively and stably,and the application of optimal RSGFD method can acquire accurate synthetic seismic recordings and enhance computational efficiency relatively.

Derivative calculation is a basic method used in data processing and interpretation of potential fields,but the instability of the result restricts the application of higher-order derivative in practical data.Thus,this paper proposes an iterative method for higher derivative calculation of potential fields to resolve the problem of instability.The authors added a lowpass filter which contained the derivative order number and derivative operator to the higher derivative operator,and used the iterative method to perform successive approximation.On such a basis,the authors deduced the recursive formula of the iterative method of higher-order derivative.In addition,the authors proved the convergence of the iterative method and made a comparative analysis on filtering characteristics of derivative operator by using different methods. In model test and application,the comparative analysis of the results of the iterative method and conventional method for higher-order derivative indicates that the iterative method has advantages of stronger stability and higher calculation accuracy.

Top (0~20 cm)and sub-layer (20~40 cm)soil samples as well as corresponding tea leaf samples were collected at seventy-nine tea gardens in Anxi County and other areas, Fujian Province. Lead concentrations of tea leaves as well as soil geochemical indicators including macro-and micro-elements were determined. There is a significant correlation between the lead concentration of tea leaves and that of the corresponding soils. Therefore, a linear regression model was established, and transfer factors(F_t) for lead from soils to tea leaves was calculated. It seems that F_t values are affected by the concentrations of lead, manganese, phosphorus and zinc in soils. The critical value of soil lead for tea production was derived from the regression model and F_t value according to tea quality criteria. The result demonstrates that the lead values of tea uptake from soils would not exceed tea quality criteria (5×10^-6) under normal soil lead concentration. Multivariable linear regression model can preferably explain the relationship between lead concentration in tea leaves and soil physicochemical indicators.

In order to investigate the geochemical characteristics of elements and evaluate the pollution condition of heavy metals, the authors collected 400 samples of near-surface atmospheric dust in Jinan City. The analyical result shows that the concentrations of As, F, Ni elements from atmospheric dust with average values of 9.5×10^-6, 512×10^-6, 26.0×10^-6 are lower than their background values of urban soil in Jinan respectively, while Cd, Cr, Hg, Pb, Se, Zn and CaO concentrations which are 0.33×10^-6, 101×10^-6, 191×10^-9, 38.0×10^-6, 0.79×10^-6, 119.0×10^-6 and 13.31% respectively are higher than their corresponding background values. Correlation analysis and principle component analysis(PCA) indicate that Cd, Pb, Zn and Se might be derived from coal combustion, Cr and Ni from soil, Cao and As from construction dust, and F from vehicle emissions; Hg is mainly controlled by anthropogenic sources comprising combustion, industrial steel and traffic activities. The values of geoaccumulation index of Cd, Pb, Zn, Cr, Ni, As, Hg in atmospheric dust vary in the range of -2.46~4.53, -1.81~2.75, -2.02~3.48, -2.38~3.48, -2.95~1.96, -3.45~2.58 and -3.04~6.87, respectively, and the pollution level of heavy metals is in order of Hg >Cd >Zn >Pb >Cr >As >Ni.

To conduct engineering geological investigation in waters, common geophysical prospecting methods frequently fail to satisfactorily determine bedrock topography as well as strike and development extent of the blind fault in the investigated area. Taking the traversing project of the Yangtze River natural gas pipeline network in Jiangjin as a study case, the authors detected the river depth, overburden thickness and bedrock topography of the whole area by adopting the transient electromagnetic method to carry out survey in waters. Drilling verification shows that data consistency is fairly good, suggesting that the transient electromagnetic method has a good prospect in waters survey.

The karst caves whose diameter is more than 1m at the depths of 0~13 m were the objects in the exploration of concealed karst of Gui-Guang Railway. Landsonar was used in the tunnel part, and 4491 karst caves more than 1m in diameter were marked along the 68km surveying line. As there is no ready-made software and standard to draw the achievement graphs in karst cave exploration, the means put forward in this paper are the best methods to take the advantage of the secondary development of AutoCAD to program a software and draw the graphs.

The middle-east area of the Qinshui coalfield is located in eastern Qinshui block depression, where terrain undulates obviously and the surface lithology is changeful. The anisotropy of shallow surface causes more impact on the efficient detection of the coalbed methane and shale gas in the seismic exploration. How to choose the excitation and receiving parameters becomes the main difficulty. In this paper, the methods of micro logging and refraction encounter were used to investigate the structures of shallow and surface. According to well logging data, the authors determined the reasonable excitation horizon so as to assure the exploration-grains explosion in the bedrock or dense clay layer; the excitation parameters of well depth, charge mass and well combination of different lithologies were obtained through the study of the systematic test of excitation and receiving condition; through the analysis of the test data,the authors chose the combination of low frequency detectors and built the recording geometry with multifold. Practices prove that the excitation and receiving parameters of this region can suppress the interference waves such as the surface wave and the multiple refraction wave and can resolve the problem of low signal-to-noise ratio in mountainous areas, especially in loess areas. The results obtained by the authors provide useful references for the exploration and development of unconventional natural gas in the future.

In normal TEM sounding,the parameter of secondary induced voltage V signal is collected by using magnetic induced coil;however,the late signal is usually too weak to identify deep buried target.In this paper,direct measuring of B field parameters is used to test its practical effect.Firstly,from the response of B field and dB/dt and numerical calculation of different models,we can see that the B field has superiority in late time detection.Then the SM24 TEM system which is used to measure B field and the GDP-32 system which is adopted to measure induced voltage are compared with each other.With the same observation parameters,B field data are more superior than induced voltage data.The characteristic frequency of fluxgate sensor is relatively low and it decays slow.In addition,the amplitude of B field data is larger than that of dB/dt data.This means is favorable for measurement in late time because the influence of low resistivity covered layer on it is relatively low.The results show that developing and using fluxgate sensor is an important direction to resolve fine TEM exploration.

We introduce a new 3D parallelgravity inversion method based on CUDA GPU in PGI Fortran,which could be used in PCs and Laptops with NVDIA graphic cards to accelerate iteration speed for Re-Weight Regularized Conjugate Gradient method up to hundreds times.Storage and threads optimization was made for visual OS, leading a more than 0.1 billion cell's number for inversion in PCs.The result of model study shows that this method is an efficient and believable parallel computing algorithm.

Overcoming the shielding effect of conductor covered layer and realizing the effective detection of low resistivity layer underground constitute an important problem in electromagnetic exploration.Short offset transient electromagnetic (SOTEM) is receiving more and more attention because of its near source observation method.In order to analyze its detection capability,the authors made a comparison with a grounded electric source frequency device-(CSAMT),which is generally used nowadays.In this paper,the response characteristics of SOTEM and CSAMT in 1-D layered media are studied.In addition,two groups of electric models of low resistivity covered layer and low resistivity interbbed with different electrical characteristics are designed.Then detection capability is comparatively studied by calculating relative anomaly error.It is concluded by analysis that SOTEM is more sensitive to low resistivity covered layer than CSAMT and hence it is more favorable for detecting underground conductor layer.

As one of the effective methods used in search for mineral resources, down-hole transient electromagnetic method (TEM) measures transient electromagnetic field in a drill hole by placing receiving coils in the drill hole. Based on time domain finite difference algorithm, the authors used loop source and non-uniform gird to simulate the response of the uniform medium in half space, inclined conductor, and inclined conductor with overburden. The results indicate that the maximum value of response decreases with delay time in uniform half space. When the source is laid on the receiving drill hole, the abnormal response is reflected apparently. When the source is laid beside the receiving drill hole, abnormal response can be observed with more observation time. The influence of overburden exists all over the observation time, which causes the decrease of the abnormal response. It is also weakened with the increasing distance between transmit loop and receiving drill hole. The research provides reference for analysis and interpretation of down-hole TEM abnormal response characteristics.

Hydrocarbon source rock is the foundation of oil and gas exploration research. Proper evaluation of source rocks and divided favorable exploration area play an important role in decision making for further exploration. At present, geochemical methods (Through analysis of the core samples it can provide accurate geochemical indicators about hydrocarbon source rock) still the main means for hydrocarbon source rock studies, which is hard to obtain a continuous data on a single well owing to the limited samples and experimental fees. In addition, source rocks have a non-mean, and by making the data from geochemical analysis simply mean treatment will lead to the information from high-quality source rocks to be suppressed, which leads to the exploration precision is difficult to meet. Logging information has a high vertical resolution and the data continuously, accurately the logging characteristics of hydrocarbon source rocks in coal measures all which provides a new approach in the correct evaluation for hydrocarbon source rocks. Coal source rock significantly different, according to the abundance of organic matter can be divided into shale, carbonaceous shale and coal, they have their own characteristics in response on the logs. Making full investigation for the existing research results which created by domestic and foreign scholars. And based on response characteristics of coal source rocks in the natural gamma, resistivity, acoustic time, neutron, density logging information, to carry out a qualitative identification and quantitative evaluation for hydrocarbon source rocks. Quantitative evaluation and qualitative identification methods of hydrocarbon source rocks in coal measures were introduced, such as crossplots method, ΔlogR method and the like. Received the data of tatal oxygen carbon by using the methods above, and achieved good results, which provide reference for comprehensive evaluation of hydrocarbon source rocks.

Starting with the model of the Biot two-phase media theory,the authors set up the 2D/3C velocity-stress elastic wave equation of the two-phase isotropic media and the finite difference time domain scheme through deduction.The wave field simulation is based on the two-phase homogeneous and inhomogeneous isotropic media using the traditional staggered-grid method and the rotated staggered-grid method.The results show that the rotated staggered grid difference scheme performs perfectly for the two-phase isotropic media.A comparison between rotated stagger-grid and traditional stagger-grid demonstrates that the finite difference algorithm of rotating staggered-grid is more stable and can avoid errors caused by interpolation,and hence the rotated staggered-grid difference scheme is a numerical simulation of seismic wave field method with a strong effectiveness.

In the process of coal mining, coal thickness and structural factors often restrict the production efficiency of coal mine. Before mining, the detection of these factors has important guiding significance for practical production. Combined with the actual geological conditions, the authors established a forward model. Based on the ray tracing theory, the authors studied factors such as coal thickness, fault and collapse column in the coal seismic exploration of reflection mechanism and response characteristics. The results show that, for the thickness of coal seam in the time domain, the thickness of 1/4 lambda can be identified, and that fault and collapse column in the seismic record is a typical section of wave, with characteristics of diffraction. The seismic response of the coal seam provides a reference for practical exploration of the inversion explanation and also provide a theoretical basis and practical guidance for the coal mining in the late stage.

The technology of advanced geological prediction can detect the geological structure of the tunnel face and predict the adverse geological conditions so as to ensure the efficiency and safety of the construction. This paper introduces the theory of Pseudo VSP and Kirchhoff migration imaging respectively, and argues that Pseudo VSP, which takes advantage of the intersection of reflection and P-wave arrival time to predict the position of reflection interface ahead, is suitable for the situation that the sources or the receivers are designed on a straight line; however, Kirchhoff migration method can be used in any observation system. This paper is based on the principle of Kirchhoff migration imaging and Pseudo VSP. Taking the Yakou tunnel as an example, the authors compared the imaging results between the two methods through a series of pretreatments,such as time-shift correcting, filtering, wave field separating, and radon transform. The results show that Pseudo VSP can predict the position of construction accurately, but it cannot predict the structural strike. Kirchhoff migration imaging which gets the information of migration velocity by velocity scan method is on the basis of reflected wave energy to determine the reflection interface, and the intersection of reflection interface and tunnel is the position of construction. Combination of Pseudo VSP and Kirchhoff migration imaging can predict the structural strike and position more precisely.

The coalbed methane content is often relatively high where the immediate roof and floor of the coal seam are mudstone. In order to predict the coalbed methane rich region, position of coal seam roof and floor and distribution of sandstone and mudstone are based on acoustic wave impedance inversion and pseudo-acoustic inversion technique through seismic data and well logging data analysis. This method provides a basis for the exploration and development of coalbed methane. First of all, the position of coal seam roof and floor can be acquired accurately in the acoustic wave impedance inversion profile due to low acoustic impedance values of coal. Pseudo-acoustic curve is constructed by natural gamma curve. In the pseudo-acoustic inversion profile which has high lateral continuity, the mudstone shows high values, the sandstone shows low values, so it is possible to characterize the sandstone and the mudstone when the range is acquired though data analysis. The application in practice shows that, the inversion method is better than conventional one in resolution and achieved good results in practice.