The Silurian Longmaxi Formation shale in the south of Sichuan Basin has the geological characteristics of large burial depth (more than 3000 meters), thin thickness of high-quality shale section,rapid change of formation dip angle,and development of micro structure and micro fracture.It is difficult for the traditional geosteering technology to accurately identify the target location of the longitudinal sweet spot.During the drilling process of horizontal section,there is a high risk of target miss target and formation production.The 3D seismic data can provide guidance for sidetracking and target entry of horizontal wells and guide horizontal drilling.Taking the seismic tracking of shale gas horizontal wells in the complex area of southern Sichuan Basin as an example,this paper introduces a new idea of horizontal well seismic guidance technology based on anisotropic prestack depth migration three-dimensional data volume.Based on high-precision imaging data and considering regional velocity field background,geological constraint velocity modeling ensures accurate target and,at the same time,real-time anisotropic depth migration of target block can be carried out.In addition,real-time seismic tracking during drilling can effectively help drilling geosteering and provide early warning and adjustment scheme for drilling engineering.The actual drilling shows that the seismic steering technology for horizontal wells in shale gas complex structural areas can effectively improve the effective reservoir drilling rate of horizontal wells for development and engineering needs.

Shale gas reservoirs have the characteristics of low porosity and low permeability.The large-scale exploitation of shale gas requires the reconstruction of shale reservoirs through horizontal well fracturing technology.Available data indicate that,when the horizontal shale gas well azimuth is approximately perpendicular to the maximum horizontal principal stress,and the coefficient of difference in horizontal in-situ stress is small,it is favorable for fracturing to form network fractures and improve the effect of reservoir reconstruction.An in-situ stress prediction model was established for the Nanchuan area.On the basis of detailed 3D seismic interpretation and 3D seismic prestack inversion,the regional adaptive parameters were selected by using well data simulation,and the 3D simulation of the in-situ stress field was performed to predict the direction of the maximum horizontal principal stress,the direction of the minimum horizontal principal stress and the coefficient of in-situ stress difference.Through an analysis of the regional stress mechanism and the interpretation of the induced joint and the analysis of the application,the reliability of the in-situ seismic prediction results was verified,and the important role of in-situ stress analysis in shale gas development was proved.

Gas content is one of the main parameters to evaluate whether shale gas can be enriched to obtain high-yield.The higher the gas content,the more favorable for shale gas wells to obtain high-yield.Traditional gas content seismic prediction methods are based on single-attribute,multi-attribute linear fitting or simple neural networks,and have low accuracy.The gas content prediction method is based on deep neural network.Through optimizing seismic attributes,optimizing the solution method and choosing the appropriate number of hidden layers,the number of neurons,and the number of iterations,a prediction model can be established to predict the gas content of shale,thus effectively improving the prediction accuracy of shale gas content and providing support for the geological evaluation of shale gas research areas and the deployment of shale gas horizontal wells.

In order to find out the occurrence status of geothermal resources in Huangniqiao area, Ninghua County, Sanming City, Fujian Province, the authors carried out geothermal exploration work in this area by using the audio frequency magnetotelluric method (AMT). Based on the analysis of the characteristics of layer structure and lithology in the work area, the fault structure distribution in the area was inferred and, according to the fault distribution characteristics, one optimized geothermal abnormal target area was delineated. Drilling shows that the well bore water-bearing formation is in good agreement with the low resistivity anomaly of AMT two-dimensional inversion. On the basis of verification, the spatial distribution model of faults in the area was constructed, and four potential fault type thermal storage areas were inferred according to AMT inversion results and fault distribution characteristics. The overall research results show that AMT method is feasible and effective for geothermal resource exploration, which can provide important reference value for the deployment of geothermal exploration in similar areas in the future.

With the gradual acceleration of the construction of Yinchuan metropolitan area, especially the further expansion of Ningdong national energy and chemical base, the Yinchuan Plain urban agglomeration has been encountered with severe environmental quality problems, especially air quality problems. Therefore, intensifying the development and utilization of clean energy, optimizing the energy utilization structure in the region and reducing harmful gas emissions are one of the effective ways to improve air quality. Based on the regional geological structure and geothermal geological conditions on the eastern margin of Yinchuan Basin, the authors used regional gravity, magnetic, electrical, seismic and drilling data to focus on the analysis of three important geothermal enrichments in deep heat sources, heat conduction channels and reservoir caps. The geothermal accumulation model on the eastern margin of Yinchuan Basin was constructed, which lays a solid research foundation for the subsequent development and utilization of geothermal resources.

In the Middle-Lower Yangtze River metallogenic belt, the possibility of the development of copper-gold mineralization similar to things of the fault-uplift area in the depth of volcanic basin has attracted extensive attention. Based on the geophysical profile through the Tongling fault-uplift area and Fanchang volcanic basin and using integrated geophysical exploration methods, the authors identified the deep geological structure, rock and ore-controlling structure and the distribution of intrusions. The comparative study shows that the lithology, height and distribution of intrusions are different in Tongling and Fanchang area, and the intrusions in Fanchang is more felsic and shallow than those in Tongling. The faults in Tongling area only control the shallow location of intrusions, while the boundary faults in Fanchang basin are the channels for magma rising. The intrusion in Tongling area is characterized by "one mother and multiple offspring" and different intrusive branches or strains derived from the same magma chamber, which directly proves that different types of intrusive rocks in Tongling area are the products of the evolution of the same magma source region, and different degrees of evolution may be one of the reasons for their different kinds of mineralization. In this study, the authors used integrated geophysical exploration methods to discuss the difference of diagenesis and mineralization between Tongling fault-uplift area and Fanchang volcanic basin and explain the reason why only small iron mineralization exists in Fanchang region while large copper (-gold) deposit occurs in Tongling region. In addition, large-scale intrusion of granitic magma in the depth of Fanchang region indicates that there is no "second Tongling" in the depth of the Fanchang volcanic basin. These results further deepen the understanding of the regularity of copper and iron mineralization in the Middle and Lower Yangtze River metallogenic belt and provide theoretical support for ore prospecting and exploration in the future.

According to the theory of 'large-scale mineralization occurring in small intrusion' and 'magma conduitsystem', the authors investigated the magma conduit of the Yangliuping magmatic Cu-Ni sulfide deposit.On the basis of the study of all geological documents, the values ofw(Pd)/w(Ir)、w(Ni)/w(Cu) were used to estimate the moving direction of magma conduit. Then geological profiles, high precision geomagnetic survey and the AMT measure were deployed in search for the magma conduit. The integrated measures in search for deeply-buried orebodies at Yangliuping was summarized.

Anqiu-Juxian fault in the Tanlu fault zone is in a concealed state in the Juxian basin.Geophysical data in the basin is very insufficient,and the distribution and spatial geometric characteristics of the fault are not clear.In view of such a situation,the buried faults in the basin were detected by shallow seismic reflection detection,and the distribution characteristics of Anqiu-Juxian fault in the basin were preliminarily discussed and analyzed in combination with the study of Zheng Chuanbei and other research results.The results show that the Anqiu-Juxian fault is located in the Quaternary sediments of Juxian basin,with relatively shallow burial depth.The fault is characterized by compressional thrust and positive fault in some sections.The shallow seismic reflection profile shows the new geophysical evidence of Anqiu-Juxian fault in Juxian basin and provides geophysical reference for the overall evaluation of the fault.

There has been no substantial progress in uranium prospecting in Tengger depression. Therefore, CSAMT is used to identify the sedimentary characteristics and structural framework of the study area, especially the lower Cretaceous Saihan formation and its sandbodies. Combined with the geological drilling data, through the forward and inverse calculation of the data in the study area, the inversion model and inversion parameters are optimized, the spatial distribution characteristics of the sand body of the lower Cretaceous Saihan formation in the study area are identified, and the development characteristics of the ancient river channel are briefly analyzed, which provides a reference for the direction of uranium exploration.

The Chahe deposit is the largest tin deposit in Sichuan Province. In order to gain a prospecting breakthrough, the authors conducted 1:50 000 stream sediment survey, studied the characteristics of element combination of this area by feature analysis and factor analysis of the measuring results. The results show that the three main ore-forming element groups of Ag-Pb-Zn, Bi-F-W-Sn and Cu-Ni have similar enrichment rules, in which the enrichment regularities of W, Sn and other medium and high temperature elements are extremely significant, and the overlapping features of the spatial distribution of the element anomalies are good.The lower limit values were determined by methods of cumulative frequency and iteration. The authors compiled the element anomaly maps and delineated nine comprehensive anomalies. By comprehensive evaluation of the anomalies, the authors consider that the Chahe and Fangjia composite anomalies are the prospective areas. The authors analyzed the geological condition for mineralization, carried out mineral inspection, and discovered a new skarn type tungsten-tin vein in the Chahe prospective area and more than ten new quartz-vein type tungsten veins in the Fangjia prospective area. The Fangjia prospective area, with a certain degree of similarity in geological characteristics with the "five-story+basement" prospecting model for tungsten deposits, has a favorite prospect in the search for polymetallic deposits such as tungsten, copper, lead and molybdenum.

In order to study the ore-forming material source and ore-forming age of the Liuying fluorite deposit, the authors tested and analyzed the REE of 11 samples of rocks and ores, and determined the mineralization age of fluorite by Sm-Nd method. The results show that the chondrite-normalized REE patterns of wall rocks (marble+mica quartz schist), fluorite ore and Niuxinshan biotite monzogranite all have a rightly-dipping trend, but the distribution curves and statistical values of different parameters of fluorite ore and biotite monzogranite are closer to each other, indicating that they have obvious genetic relationship.The metallogenic age of fluorite is 141 Ma and the values of εNd(t) are negative, which shows that the main metallogenic epoch is early Cretaceous and the crust source characteristics are obvious. The metallogenic age of fluorite ore is basically consistent with that of SHRIMP zircon U-Pb age of Niuxinshan biotite monzogranite (132.4~138.4 Ma), suggesting that there is a close relationship between them, and the material sources should be consistent or similar.

Mianluening area is one of the most complex areas of geological structure around the Yangtze plate. Based on the comparative study of the high magnetic anomaly zone to the west of Baiquesi basic complex, the regional gravity anomaly gradient zone and the geochemical anomalies of Fe, V, Ti and other elements, combined with the geochemical characteristics of the overflow phase basalts distributed along the anomaly zone, it is inferred that there may be a larger hidden fault in the deep part of the NNE-trending shallow faults interpreted by surface remote sensing. This hidden deep fault may have provide an important channel for the mantle-derived magmatic activity in the context of post arc cracking in Mianluening area in the Neoproterozoic. On the one hand, the Baiquesi basic complex and igneous carbonatite were formed by the intrusion of the plutonic magma; on the other hand, the belt like overflow phase basalt rich in magnetite was formed by the fissure type volcanic eruption. This finding is of great significance for the study of Neoproterozoic tectonic setting and mantle-derived magmatic mineralization in Mianluening area.

The Guanzixia M exploration area in Huining County is located in the hilly and gully area of the Loess Plateau,which has a good prospect of prospecting for graphite ore. Firstly, graphite ore metallogenic conditions in the exploration area are analyzed. Then, the geophysical work is carried out in the favorable area of graphite mineralization. Adopting the dual frequency induced polarization intermediate gradient to measure the apparent amplitude frequency, apparent resistivity and the natural electric field adopted to measure natural,the two methods are used to delineate graphite mineralization anomalies,which are characterized by high amplitude frequency, low apparent resistivity and negative anomaly of natural potential. On this basis, the induced polarization sounding is used to find out the spatial distribution characteristics of mineralized anomalous bodies, and provides evidence for drilling through various methods. It has been verified by drilling that 2 layers of graphite ore are drilled, and obtained good exploration results.

The Jiama mining area in Tibet is one of the most important large deposits in the eastern Gangdise porphyry copper belt. There are many kinds of rocks, and the physical properties of different strata and intrusive rocks are complex and diverse. In the past, due to the lack of enough attention to the physical properties of rocks, the types of rock determination were not comprehensive enough, and there was a lack of systematic and complete understanding of the physical properties of rocks in the Jiama mining area. On the basis of an analysis of rock physical property data in the past and through the physical property measurement and statistical analysis of core samples from six typical boreholes in the Jiama mining area, the characteristics of rock density, magnetism, resistivity and polarizability in the mining area were summarized, and the rock geological geophysical model of the mining area was established, which provides a reliable basis for the subsequent geophysical work in the mining area. Secondly, the rock electrical parameters were used to correct the static effect measuring points on the magnetotelluric sounding profile in the mining area so as to provide the basis for the magnetotelluric sounding profile interpretation and guide the magnetotelluric data processing and interpretation in the mining area. Through the comparison and verification of drilling data, good exploration results were achieved.

In order to discuss the deep-penetrating geochemical ore prospecting method suitable for the humid environment in southern China, this paper adjusted some experimental parameters based on the enzyme leach method to form a set of indoor and outdoor operating procedures for the analysis of amorphous manganese adsorption. We chose to verify the effectiveness of the analytical method for the adsorption of amorphous manganese at the No. 505 geological prospecting line in the Wangu Gold Mine, and compared the results with the two methods of traditional soil full-scale testing and rock measurement methods. The comparison results show that the analysis method of amorphous manganese adsorption can effectively find geochemical anomalies above the concealed ore. The leaching rate of 100 mesh samples showed the characteristics of Cl>Br>I>Au>Ag>Sb>As.The anomalous sensitivity of Au and Sb detected by the amorphous manganese adsorption analytical method is higher than that of the soil total measurement, and it agrees well with the geochemical anomaly of rock measurement.

Pulsed neutron-neutron (PNN) logging technology through casing can identify fluid properties by measuring the number of thermal neutrons not captured by formation.It solves the problems of unclear response of electrical logging in watered-out zone and the influence of gamma background on neutron lifetime logging.In this paper,an adaptive genetic algorithm was utilized to eliminate the influence of non-geological factors and obtain the optimum solution of PNN interpretation parameters by setting the probability of selection,crossover and mutation and selecting the initial population in the standard layer.In view of the great change of salinity of mixed formation water due to interval injection by fresh water and sewage,the authors propose a variable parameter PNN interpretation method for calculating the macroscopic capture cross section of mixed formation water in small layers,so as to accurately identify the flooded layer and greatly improve the calculation accuracy of residual oil saturation.

Vibroseis technology is widely used in desert,Gobi and deep phreatic surface areas where drilling is difficult.In the process of field exploration,it is necessary to select suitable parameters to ensure the effect of seismic exploration.In this paper,the J mining area coal field seismic exploration was chosen as the research object and,for the purpose of improving the seismic data resolution and signal-to-noise ratio(SNR),the sweep frequency range,scanning length,driving level and vibration frequency of vibroseis parameters were tested.Through the combination of qualitative and quantitative analysis,the best excitation parameters were selected for data acquisition,and the high quality of seismic data were obtained on the seismic time profile,which shows the good application effect.The results prove that it is effective and feasible to use vibroseis acquisition technology in coal field seismic exploration in areas where explosive excitation is difficult.

Block C of the East China Sea has the characteristics of complex fault block development,strong stratigraphic heterogeneity,and complex reservoir connectivity.Affected by acquisition and other factors, the random noise of seismic data is relatively serious, which brings great challenges to subsequent exploration and development work.To eliminate random noise effectively and keep the structure information of seismic reflection at the same time,this paper proposes a de-noising method by combining anisotropic diffusion filter technique and F-X edge-preserving filter method.The new method obtains the dip and azimuth of the target formation by gradient structure tensor,extracts the filter window at the target point under the constraints of the dip and azimuth information,and uses adaptive F-X filtering in the filter window to suppress random noise,finally reaching the goals of improving the continuity of seismic reflection in complex fault zone and enhancing the coherence of reflection event and highlighting the edges.The results of 3D modeling and application in real 3D data indicate that the new method has effectively smoothed the reflection events without blurring relevant details of faults and discontinuities on seismic sections. Compared with conventional de-noising method,the new method can improve signal-to-noise ratio and protect seismic reflection and structural information.Meanwhile,the continuity of the edge information of the geological body is better displayed in the time slice.

Inverse Q filtering is one of the practical methods for improving the resolution and preserving the amplitude of seismic data,and hence it has important practical value in seismic reservoir prediction.Researchers have been studying the function of amplitude for a long time,and have found that the inverse Q filtering method using time-varying amplitude compensation function is one of the current research and improvement directions.In this paper,by studying several commonly used and effective inverse Q filtering methods,a time-varying gain limit inverse Q filtering method based on the Teager-Kaiser energy principle to obtain the gain limit of the amplitude compensation function is proposed,which improves the traditional inverse Q filter.The new method calculates the time-varying gain limit of the compensation function based on a smooth continuous function instead of the piecewise function or cut-off frequency used in traditional inverse Q filtering.Therefore,the new method has the advantage of stably adjusting the time-varying gain limit,so it can increase the accuracy of the inverse Q filter,especially for the amplitude preservation and resolution improvement of deep media.The effectiveness and practicability of the proposed method were proved with theoretical models and practical data.

Magnetic resonance sounding is a geophysical exploration method based on the difference of relaxation characteristics of hydrogen proton in geomagnetic field. It can detect the content and distribution of groundwater without damage. In recent years, with the expansion of the application of magnetic resonance sounding, this method is often faced with the detection when the surface has a large slope. When traditional inversion methods are used, inaccurate inversion results often occur. In this paper, the angle between the geomagnetic field vector and the coil is introduced, which is called the effective geomagnetic inclination, and the inversion method of the magnetic resonance sounding under surface slope is given. According to the prior information provided by geological data or other geophysical methods, the distribution of parallel or horizontal layered kernel functions of the magnetic resonance sounding is obtained, so as to carry out the inversion of the NMR signal under the condition of surface slope. In this paper, 1D and 2D aquifer models are constructed with the sloping surface, the corresponding NMR signals are obtained by forward calculation, and the kernel functions calculated by effective geomagnetic inclination and traditional method are used for inversion. The results show that, in the case of surface slope, the traditional inversion method of magnetic resonance sounding will inevitably produce errors, while the kernel function calculated by effective geomagnetic inclination can suppress the influence of surface slope. The validity and feasibility of the method were verified by the inversion of the filed NMR data in Baishuihe landslide area. Therefore, the inversion method based on the effective geomagnetic inclination proposed in this paper can greatly improve the application scope of magnetic resonance sounding.

Due to the influence of the artificial boundary condition, when the conventional finite element method is used to carry out the forward simulation of the three-dimensional geophysical field in a limited space, local abnormal distortion may occur, which affects the accuracy of the numerical simulation. This problem is usually solved by expanding the edge, but this requires a larger range, which greatly increases the computational cost and affects the efficiency of forward simulation. In this paper, on the basis of COMSOL Multiphysics software, infinite elements are set on the external boundary to replace the traditional boundary conditions so as to reduce the calculation area. Compared with the traditional finite element method, the finite element infinite element coupling method, by setting the isolated sphere and the combined body model and considering the conditions of demagnetization, remanence and surface undulation, can effectively overcome the boundary effect, improve the calculation accuracy and reduce the amount of calculation, thus improving the forward numerical simulation efficiency of the finite element method.

When the transient electromagnetic receiving antenna is in a critically damped state, the output signal is the pure target induction signal. This critical damping state is related to electrical parameters such as inductance, distributed capacitance, and resistance of the receiving antenna. The resistance and inductance values can be directly measured by a spectrum analyzer, but the distributed capacitance cannot be directly obtained. In order to develop a high-performance receiving antenna, this paper proposes a method to accurately calculate the distributed capacitance of the receiving antenna. First, the equivalent circuit model of the transient electromagnetic induction receiving antenna is constructed; then, the calculation formula of the zero-phase resonance frequency of the output signal is derived; Finally, by measuring the resonant frequency of the antenna, the distributed capacitance is calculated. For the purpose of verifying the feasibility of this method, the standard capacitance is compared with the calculated capacitance, and different types of transient electromagnetic induction antennas are tested. The test results show that the zero-phase method can be used to calculate the distributed capacitance with high accuracy, convenience and fastness and can be used to design and produce high-performance transient inductive sensors.

Geodetic polarization exploration technology is a passive source geophysical electromagnetic exploration method using natural electromagnetic radiation. Based on the piezoelectric effect of rock, the expression of electromagnetic radiation produced in the process of rock fracturing was derived. The influence factors of electromagnetic radiation frequency were analyzed, and the frequency response characteristics of electromagnetic radiation from fracturing were studied by numerical simulation. The results show that the geodetic polarization exploration technology based on the piezoelectric effect of rock has similar electromagnetic response characteristics to other electromagnetic detection methods, and the geodetic polarization exploration technology has potential application value.

Deep learning is an extension of the artificial neural network algorithm, which has a good approximation ability for complex functions. This paper introduces this means for the calculation of transient electromagnetic apparent resistivity. First, a 5-layer deep neural network is established with a single mapping relationship between the normalized induced electromotive force and the transient field parameters. By analyzing the error conditions trained by different numbers of neurons in a single hidden layer, the hidden layers of the 5-layer deep neural network are determined. The number of layered neurons is 13,8,5,8,13. The training algorithm chooses the improved Nadam algorithm with adaptive learning rate, which can speed up the training process. The trained deep neural network model is simulated and verified by a typical electrical model, and it is found that it has a good response to different geoelectric models, which proves the feasibility of calculating apparent resistivity based on deep learning put forward in this paper. The actual application results show that the trained deep neural network model can quickly and accurately calculate the apparent resistivity, and its effectiveness is verified by drilling.

ZTEM is a new-type frequency-domain airborne electromagnetic system which measures the magnetic fields that result from natural source. Tipper is adopted as a research parameter that relates the vertical magnetic field at the observation point to the horizontal fields at a ground based reference station, which can be used to perform large-scale structural exploration with topography. Based on the 3D finite-difference forward modeling and data-space OCCAM inversion of ZTEM, the authors have developed a frequency-domain 3D forward and inversion algorithm for ZTEM tipper data including surface tomography. At first, the forward code is verified for its correctness and applied to calculate and analyze the characteristics of 3D ZTEM abnormal response generated from undulate tomography. Then, the synthetic conductive models of 3D ZTEM inversion results including peak and valley terrain show that the algorithm can get the inversion models which are close to the underground real conductive structure; especially, it has an ideal constraint effect on the horizontal boundary of the underground object. At last, the results of synthetic example are compared with the results from 3D ZTEM inversion with no tomography implications to demonstrate the validity of the data-space OCCAM approach for inverting tipper data of ZTEM.

As one of the key parameters of coal seam exploration and development research, coal structure affects coal seam productivity, and it is significant to effectively identify coal structure. In this paper, the support vector machine algorithm was used to identify the coal structure based on geophysical logging data, and the No. 3 layer in Shizhuang North District of Qinshui Basin was taken as an example to classify the coal structure type in this block. Using two modeling modes of support vector machine's two-two classification and "one-to-many" classification, the authors established a coal structure recognition model based on logging curves, then used cross-validation to evaluate the generalization of the model, and finally used the data that did not participate in the model establishment to evaluate the accuracy of the model. The results show that the two models of the support vector machine algorithm can effectively identify the coal structure, the models have generalization and accuracy, and the "one-to-many" classification model has higher accuracy: the distinguishing effect of coal is outstanding, it is accurate in distinguishing the specific types of coal that are beneficial to production, and can provide guidance for subsequent fracturing construction. In general, the coal structure recognition model established based on the support vector machine algorithm and geophysical logging data has guiding significance for the exploration and development of coalbed methane and shows practical application value.

Based on the data of soil element content obtained from agricultural geological survey in Wuping County, Fujian Province, the authors studied the distribution characteristics of soil selenium content and its controlling factors. According to the result obtained, the average value of selenium content in the study area is 0.25×10^-6, the high value area of soil selenium is mainly distributed in the south and east of the investigation area, and the average value of selenium content is 0.42×10^-6, reaching the standard of selenium enrichment; the selenium content of the soil in the study area is mainly controlled by the geological background, and the content of selenium in the Carboniferous and Permiancarbonate strata and coal-bearing strata is relatively high The average selenium content of marine sedimentary rock area is the highest, reaching 0.34×10^-6. The average values of selenium content in pyroclastic rock, granite area and metamorphic rock area are similar, being 0.25×10^-6 and 0.24×10^-6, respectively. Soil selenium content in tea garden (0.57×10^-6) and orchard (0.40×10^-6) is higher than that in paddy field (0.25×10^-6). Soil physical and chemical properties have an important impact on selenium content, which shows that soil selenium content has significant correlation with soil pH, organic matter and iron oxide.

The geological conditions in the karst-developed area are complicated.The geological conditions directly affect the bridge design plan.On the basis of comprehensive research on the topographic and geomorphological characteristics and geological conditions of the bridge area of the Xiangjiang River Bridge in Zhuzhou and with the purpose of ascertaining the type and scale of karst development in the bridge site area and the location of each bridge pier,the authors used such means as high-density electrical method,magnetotelluric survey,shallow water earthquake and CT between holes in the survey.Verification results in the anomalous area show that the detection results are accurate and reliable,indicating that the integrated geophysical method is accurate and effective for bridge site survey.The bridge span layout scheme and pile foundation laying height were adjusted to make the layout span and pile length more reasonable,thus successfully avoiding karst,realizing the geological priority and forming the bridge design scheme for site selection.

The concealed structure existing above the tunnel is very likely to induce tunnel geological disasters during construction. This paper introduces terrain correction technology based on orthogonal projection method and high power supply voltage technology with multiple electrodes laid at once into the traditional electrical sounding method to improve it. In addition, the improved electrical sounding method is applied to the detection of the concealed structures of long and deep buried tunnel. The exploration results fully reflect the spatial distribution of concealed structures and show good consistency with the drilling results. This study shows that the improved electrical sounding method can effectively detect the change of resistivity of geological bodies along the survey line profile, and can accurately identify the scale and location of concealed structures, thus providing a basis for tunnel safety construction and tunnel geological disaster prevention.

The gamma retest of the old well in the oil hole is an economical and practical method to measure the radioactivity by FD-3019 probe tube when the oil well maintenance team takes out the sucker rod. Due to the influence of cementing cement ring in oil drilling on gamma logging results, the current gamma logging code has only the correction of molten iron coefficient but no correction of absorption attenuation of cement ring. Therefore, gamma reiteration data can be used to appraise drill radioactive anomaly correctly through the cement ring attribute parameter correction. It is concluded that the main influence parameters of cementing cement ring are cement ring density and cement ring thickness. By making a number of cement ring model holes with different thickness and density, simulating down hole conditions, establishing models and using different model cement ring absorption coefficient values, the authors finally found out the influence coefficient of cementing cement ring on gamma logging illumination rate and carried out correction and demonstration experiments to make the revised data infinitely close to the true formation value. Combined with the actual data of an oil field block in Inner Mongolia, the authors revised the data through the modified coefficient of cement ring experimental logging and discussed the relationship between the density, thickness of cement ring and the irradiation rate. The feasibility of the method is validated by verifying hole technology. The result provides the correction basis for guiding the results of the next re-survey of old oil wells.