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  • Table of Content
      20 October 2019, Volume 43 Issue 5 Previous Issue    Next Issue
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    Thoughts on the geochemical mechanism of gold mineralization in the northwest Jiaodong gold province
    Sheng-Ming MA, Li-Xin ZHU, Liang-Liang ZHANG, Jian WANG
    Geophysical and Geochemical Exploration. 2019, 43 (5): 925-931.   DOI: 10.11720/wtyht.2019.0198
    Abstract   HTML ( 605 )   PDF (4365KB) ( 391 )

    The borehole rock measurement of Jiaojia, Haiyu and Dayingezhuang gold deposits in northwest Jiaodong gold province shows that the multi-attribute geochemical anomaly system, which consists of mineralizer element S, major element Na2O and ore-forming element Au, progressively indicates the gold ore-forming conditions, metallogenic prospect and geochemical basis for deep prospecting. Through a study of formation mechanism of multi-attribute geochemical anomaly, this paper puts forward the geochemical mechanism of gold mineralization in northwest Jiaotong gold province, which can be summarized as ore source, sulfur enrichment, recombination, fluid and heat, coupling and centripetal. Based on the study of 40 experimental areas, the authors hold that the ore-forming geochemical mechanism of the Jiaojia-type gold deposits and the other hydrothermal metallic mineral deposits is the innovation and development of theory and method on the exploration geochemistry application.

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    Research,development and application effect of comprehensive evaluation technique of valley system secondary halo-remote sensing-tectonic lithofacies in basin-orogen-plateau inlaid structure and special landscape zone, Bolivia
    Yu-Long DU, Wei-Xuan FANG
    Geophysical and Geochemical Exploration. 2019, 43 (5): 932-947.   DOI: 10.11720/wtyht.2019.1436
    Abstract   HTML ( 6 )   PDF (6675KB) ( 407 )

    In this paper, the authors carried out tentative research and promotion application, which constitute an integrated approach to valley system secondary halo-remote sensing-tectonic lithofacies interpretation in basin-orogen-plateau inlaid structure and special landscape zone of the Tupiza and Cuprita copper deposits, Bolivia. Key points of combinational method and application effect are as follows: ① The key is interpreting mapping unit by remote sensing-tectonic lithofacies, which serves as base map of valley systems secondary halo and tectonic lithofacies mapping unit. Remote sensing-tectonic lithofacies interpreting can identify topography and landscape cell rapidly, and improve effective point ratio of geologic mapping and sampling of valley systems secondary halo. ② Sampling horizon and sampling depth were determined tentatively. It is known that the main sampling horizon is B soil and the best sampling size fraction is -10~+60 mesh grain size. ③ The technical method has achieved good results in application and promotion in the Tupiza and Cuprita copper deposits, which proves that the combination of technical methods is an economic, efficient and rapid comprehensive evaluation technique in basin-orogen-plateau inlaid structure and special landscape area of Andes. It also provides an effective exploration route of overseas investment, so as to control risk for Chinese-funded enterprises.

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    An analysis of multivariate uranium metallogenic information and metallogenic prognosis in Linxi-Ulanhot area
    En ZHANG, Ming DUAN, Hui-Xiong LU, Bo FENG, Qiu-Yi CAO, Yan-Chao YANG
    Geophysical and Geochemical Exploration. 2019, 43 (5): 948-957.   DOI: 10.11720/wtyht.2019.1353
    Abstract   HTML ( 7 )   PDF (1554KB) ( 459 )

    Located in the south-central part of Da Hinggan Mountains uranium metallogenic province, Linxi-Ulanhot area is characterized by strong tectonic magmatic activity and favorable geological conditions for uranium mineralization. Limited by such factors as vegetation development and thick cover, it is difficult for the single exploration method to meet the demand of the current deep prospecting. Based on the analysis of ore-forming conditions and ore-controlling factors, the authors constructed a comprehensive volcanic-type uranium ore comprehensive prospecting model by integrating such pieces of multivariate information as airborne radioactivity, aeromagnetic survey, geochemistry and remote sensing. Using spatial analysis function of the geographic information system (GIS), the authors extracted the multivariate prospecting information, carried out quantitative prognosis for uranium ore by evidence weighting method, and selected 16 evidence layers closely related to mineralization. Among them, the Upper Jurassic Manketouebo Formation is the main ore-bearing strata, the Late Jurassic-Early Cretaceous subvolcanic rocks are closely related to ore formation, the ore-controlling effect of NE-NNE trending fracture is significant, and uranium mineralization is mostly developed in the fault-dense zone and the intersection zone. Such anomalies as airborne radioactive anomalies (U high field, F high value halo, U/K high value halo, Hu low value halo), geochemical anomalies (Mo, Ag, Pb, W, Sn) and remote sensing alterations (Iron alteration, hydroxy alteration) play important roles in the indication of volcanic uranium mineralization. According to the posterior probability determined by the evidence weight method, 18 prospective areas were delineated, covering most uranium deposits (ore spots) in the area, indicating that the prediction results are reliable. In seven of them, uranium deposits (ore spots) were found for the first time. All these places have excellent metallogenic geological conditions, rich prospecting clues and good prospecting prospects, and the results obtained by the authors have certain guiding significance for further prospecting.

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    The application of integrated geophysical prospecting method to the prospecting for concealed orebodies in the northern area of the Weilasituo copper polymetallic deposit
    Zhen-Liang WANG, You-Mao DENG, Yin-Sheng MENG, Rui-De LIU
    Geophysical and Geochemical Exploration. 2019, 43 (5): 958-965.   DOI: 10.11720/wtyht.2019.0293
    Abstract   HTML ( 6 )   PDF (2845KB) ( 627 )

    The northern area of the Weilasituo copper polymetallic deposit is covered seriously. It is difficult to find concealed orebody with the surface geological means; therefore, in this paper, based on the study of geological data, the authors investigated the study area by using the comprehensive exploration methods such as gravity, magnetic survey, induced polarization in median gradient array and CSAMT. On such a basis, three faults were detected through inference, two metallogenic prediction target areas were delineated and, by drilling, a concealed orebody was successfully found. The combinational technologies and methods in the search for concealed orebodies in the coverage area was summarized.

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    Geochemistry and oil-source rock correlations in the Shuanghe oilfield, Biyang sag, Nanxiang basin
    Xin-Wen ZHANG, Xuan-Bo GAO, Yun-Fei YANG, Chun-An XIE, Jing-Juan TAN
    Geophysical and Geochemical Exploration. 2019, 43 (5): 966-975.   DOI: 10.11720/wtyht.2019.1470
    Abstract   HTML ( 2 )   PDF (4598KB) ( 445 )

    In this paper the authors mainly studied geochemical characteristics and oil-source rock correlations of 28 oil samples from the Shuanghe oilfield based on the gas chromatography-mass spectrometry and biomarkers. The results indicate that the peaks of C19, C20, C21- tricyclic terpanes gradually rise and the peaks of C27~C29 steranes are characterized by "V" shape of crude oils in the Shuanghe Oilfield. Besides, the concentration of gammacerane is high. The peak shapes of saturates are characterized by "prepeak" and "double peak", and the relative values of diasteranes and tricyclic terpanes are low in oils from upper layer of the Eh3 member. However, the peak shapes of saturates are characterized by "prepeak" and the relative content of diasteranes and tricyclic terpanes is high in oils from lower layer of the Eh3 member. For both the oils of Eh2 member and Eh3 member, the sedimentary environments are reductive and are sourced from higher plant and aquatic organism. However, the maturity of the oil from lower layer of Eh3 member is significantly higher than that of the oil from the upper layer of Eh3 member. In conclusion, the oils from the lower layer of Eh3 member are mainly sourced from the lower layer of Eh3 member, and the oils from the upper layer of Eh3 member are sourced from lower and upper layer of Eh3 member.

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    The application of geophysical exploration to prospecting for silver-lead-zinc deposits in shallow cover areas of eastern Xiaoshan
    Bing-Kun BI, Yun-Zhen CHANG, Qiang SHI, Sui-shui SHEN
    Geophysical and Geochemical Exploration. 2019, 43 (5): 976-985.   DOI: 10.11720/wtyht.2019.1422
    Abstract   HTML ( 6 )   PDF (2812KB) ( 613 )

    According to the physical character difference between the exploration object geological body (silver polymetal-bearing structural alteration zone and granite porphyry mass) and the wall rock, the authors employed such integrated geophysical exploration methods as high-precision magnetic survey, IP intermediate gradient and IP sounding to prospecting for concealed silver polymetallic deposits in the shallow cover area of eastern Xiaoshan. High-precision magnetic survey was used to divide favorable prospecting targets, IP intermediate gradient method was utilized to delineate favorable ore-forming sectors of mineralization and alteration, and IP sounding was used to optimize drill hole layout. In this way, the ore-intersecting rate was increased, and important breakthrough was made in ore prospecting.

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    A study of magnetotelluric sounding of Xiushui Basin in the northern periphery of Liaohe
    Peng-Hui ZHANG, Xiao-Bo ZHANG, Yong-Zhen YUAN, Hui FANG, Jian-Xun LIU, Chun-Xiang JIANG
    Geophysical and Geochemical Exploration. 2019, 43 (5): 986-996.   DOI: 10.11720/wtyht.2019.0090
    Abstract   HTML ( 6 )   PDF (4924KB) ( 521 )

    Xiushui Basin is a small-sized Mesozoic fault depression located in the south of Zhangqiang fault depression where good indications of oil and gas have been drilled in its volcanic reservoirs in recent years. In order to find out the boundary, internal framework and stratigraphic distribution of the Xiushui Basin, the authors conducted magnetotelluric sounding and gravity and magnetic profile measurement along two survey lines and, as a result, obtained the magnetic anomaly curves and the shallow electrical structures of the Xiushui Basin and its peripheral east and west sides. Constrained by drilling, geological and petrophysical data, the electrical structure characteristics of strata in different ages were determined, and the regional geological-geophysical model was synthetically established. The results show that the overall caprock of Xiushui Basin has low resistivity, which is apparently different from that of underlying basement. The basement of Xiushui Basin consists mainly of Upper Paleozoic strata, and the composition of the basement in the north is different from that in the south. In addition, the basement on east and west sides of the periphery of the basin consists of Precambrian metamorphic rock series. The basin has a structural pattern of two concaves and one uplift, relatively larger in the eastern sub-depression. The understanding obtained by the authors provides reliable geophysical basis for the oil and gas resources evaluation in the Xiushui Basin and Mesozoic basins in the periphery of the Songliao Basin.

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    A tentative test on the magnetotelluric sounding method for rapid evaluation of the metallogenic prospective area for Cenozoic basin salt deposits
    Chang-Cheng WANG
    Geophysical and Geochemical Exploration. 2019, 43 (5): 997-1002.   DOI: 10.11720/wtyht.2019.1142
    Abstract   HTML ( 3 )   PDF (2016KB) ( 382 )

    The rock salt containing gypsum, halite and sylvite has experienced crystallization and deposition successively at the subsidence center of the basin through the evaporation of sea water or lake water, and the burial depths are mostly at 0~4 000 m. At present, the methods of evaluating the metallogenic prospective area of the basin are mainly composed of gravity exploration and drilling combination and two-dimensional earthquake and drilling combination, whose construction cost is relatively high and the working cycle is relatively long. In order to rapidly evaluate the ore-forming prospective of the salt-bearing basin, the authors chose the Gaojiabao structure in the Cenozoic Bohai Sea Gulf whose study level has been very high as the experiment area and, constrained by drilling data available, carried out the study of applying magnetotelluric sounding method to evaluating salt type deposits. It is found that the low-resistivity center obtained by the magnetotelluric sounding method is quite consistent with the rock salt distribution area, and the low-resistivity body reflects the depositional center of the rock salt. The authors tentatively hold that the combination of magnetotelluric sounding method and drilling can rapid evaluate the ore-forming prospective area of salt type deposits in the Cenozoic basin.

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    Metallogenic specialization of late Jurassic S-type granites in middle-northern Jiuling Mountain in northwestern Jiangxi
    Sheng-Bing LIAO, Ping-Li CHU, Zheng DUAN, Wen-Cheng HUANG, Yan-Hui ZHU, Xu-Jie SHU
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1003-1014.   DOI: 10.11720/wtyht.2019.1463
    Abstract   HTML ( 2 )   PDF (3234KB) ( 326 )

    The zircon U-Pb geochronology, petrogeochemistry, zircon and biotite mineral geochemistry of biotite monzogranite (-porphyry) in Shimenlou area of northwestern Jiangxi province have been studied. The LA-ICP-MS zircon U-Pb 206Pb/ 238U weighted average ages of zircons from the biotite monzogranite (-porphyry) are in the range of 145.6~148.4 Ma, suggesting late Late Jurassic. The rock is common low fractionation S-type granite. The magma properties are moderately reductive (the ratio of Fe2O3/FeO = 0.18~0.19, the ratio of Ce 4+/Ce 3+ =14~158, log10(fO2)D=-22.4~-6.9, averaging -13.8 (> IW-3.6)), strong evolution (the ratio of K/Rb =153~206), low fractionation (the ratio of Rb/Sr =1.6~4.2) and low temperature (T(zircon)Ti = 619~881℃, averaging 750℃). The magma was derived from the magma source enriched area of the upper crust, which was formed by remelting and regenerating of the Neoproterozoic granitoids derived from the early Mesoproterozoic crustal material (Shuangqiao Mountain Group). The rock has the metallogenic material, time and spatial specialization and metallogenic possibility of forming tungsten deposit.

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    The latest progress in air gravity measurement and data processing technology abroad
    Hong ZHANG, Neng ZHOU, Xiao-Dan DENG, Meng WANG, Xing-Su LI
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1015-1022.   DOI: 10.11720/wtyht.2019.0085
    Abstract   HTML ( 5 )   PDF (1180KB) ( 662 )

    As a new geophysical exploration technology, airborne gravity has developed rapidly. It is of great significance and practical value to master the latest foreign technology for carrying out this survey and research in China and catching up with the advanced world level. In this paper, for the first time, the latest airborne gravity survey and data processing technologies abroad were comprehensively studied and summarized. The most advanced systems integration, survey methods and data processing technologies abroad were systematically introduced. The analysis and comparison were carried out, and the future development trend was prospected. Therefore, readers can fully understand the most advanced airborne gravity technology abroad, and directly and deeply use these technologies in survey and research, so as to promote and push forward the development of airborne gravity technology in China.

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    Pattern search algorithm for micro-seismic velocity inversion:A case study of K oilfield,Bohai Bay Basin
    Hao YAN, Bin LI, Hai-Feng ZHAO, He-Bing TANG
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1023-1029.   DOI: 10.11720/wtyht.2019.0139
    Abstract   HTML ( 7 )   PDF (5561KB) ( 384 )

    Whether it is the cross-well seismic survey or hydraulic fracturing micro-seismic survey,all we need to know is the relatively accurate formation velocity.This paper presents a new method for micro-seismic layer velocity inversion.First,the logging data and geological knowledge are used to establish an initial velocity model,and then the first arrival time of the perforation record is picked up.Because the excitation time of some seismic records is difficult to be determined,the objective function is established by using the time difference between the seismic traces.Finally,the pattern search algorithm is used to find the optimal solution of the objective function.The model trial results and the application of actual data show that the method has better results for the layered media model with fewer parameters.The method provides some reference for the fracturing and other technologies in the Bohai Sea.

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    CRP gather optimal processing and its application to S area of Daqing oilfield
    Pei-Nan BAO, Wei-Hong WANG, Wen-Long LI, Song-Jie CHU
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1030-1037.   DOI: 10.11720/wtyht.2019.1396
    Abstract   HTML ( 6 )   PDF (11430KB) ( 665 )

    Prestack inversion has an extensive application in the hydrocarbon and fluid prediction.Inversion algorithms as well as the quality of input seismic data often exhibit direct impacts on its accuracy.At the same time,prestack inversion mainly uses prestack migration seismic data.The effect of seismic imaging and the quality of CRP gather as the basic data of prestack AVO/AVA inversion has a great influence on the inversion results.In this paper,the S area of Daqing oilfield was taken as an example.There are plenty of problems in Kirchhoff integral prestack time migration gather,such as low signal-to-noise ratio,strong random noise energy,internal multiple and uneven energy between traces.In order to effectively carry out prestack inversion calculation,the authors take into account the acquisition and processing parameters of seismic data and consider that a series of seismic data pre-processing should be carried out to solve these problems in seismic survey.On the basis of numerical analysis,Radon transform,Prestack random noise attenuation and Offset energy compensation are used to effectively improve the signal-to-noise ratio of seismic data and to compensate gather energy.Radon transform can effectively suppress regular interference such as multiple waves,prestack random noise attenuation can suppress random noise in CRP channel and Offset energy compensation can effectively restore the AVO characteristics of seismic data.After optimization,the continuity and resolution of CRP gathers are improved to a certain extent,and the characteristics of wave groups are clearer.After de-noising,the amplitude plane attributes of CRP gathers before and after optimization are compared and analyzed.It is further shown that the abnormal energy of CRP gathers at the section is well suppressed and the transverse seismic waves are suppressed.The amplitude and energy characteristics of the seismic data are relatively balanced,that is to say,the optimization processing enhances the lateral contrast of seismic data,which is conducive to seismic attribute feature extraction,sand body characterization and reservoir prediction.The comparison and analysis of gathers,synthetic seismograms,stacked sections,forward gathers and actual gathers before and after seismic data processing in the study area show that the gather quality is effectively improved by gather optimization processing,and the optimized gathers are applied to subsequent prestack inversion and reservoir prediction.

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    The application of seismic exploration method to ctive faults detection in urban thin overburden area
    Dong-Wei MA
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1038-1045.   DOI: 10.11720/wtyht.2019.0066
    Abstract   HTML ( 4 )   PDF (7192KB) ( 505 )

    Currently,seismic explorations is the main geophysical prospecting method for detecting active fault lines in cities.In the detection of the active faults in Xinyi City,the wave reflected from the top of bed rock can only be recognized using P-wave reflection due to the thin overburden in local area.In general,it is difficult to determine the exact location of a fault and the burial depth of the upper breaking point based on the change of a single coaxial axis in seismic reflection profile.The method of S-wave reflection is characterized by high resolution and strong stratification capability,which can make up for the shortcomings of P-wave reflection exploration,thus improving the precision of exploration.In addition,there exist strata of two different ages on both sides of some faults in this exploration area,and there are obvious differences in velocity between them.The seismic velocity profile obtained by seismic tomography can reflect the changes of underground velocity structures and also reveal the existence of shallow faults.Through this comparison and comprehensive analysis of the results obtained by these geophysical prospecting methods and the combination of geological data,the ideal geophysical prospecting results and sound exploration results are reached.

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    The application of precise point positioning to local geophysical prospecting in the Tibetan Plateau
    Hui DU, Tao GENG, Xing-Xing DUAN, Xian-Kun JI, Yun BAI
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1046-1053.   DOI: 10.11720/wtyht.2019.0103
    Abstract   HTML ( 4 )   PDF (2070KB) ( 354 )

    The precise point positioning method has such advantages as no control point and the fact that single receiver can obtain high precision coordinate results by static measurement. It has wide application in geophysical exploration in the Tibetan Plateau and other difficult areas. This paper is based on the dealing with observation data of control points formed by two 1:250,000 regional gravity survey projects in the west and east of the Tibetan Plateau using the precise point positioning method; by calculating and comparing the difference between the precision single point positioning result of these points and the CGCS2000 coordinate result obtained by traditional measurement adjustment method, the error source is analyzed. It is concluded that the main source of the error of two coordinates is caused in the calendar and frame difference, and then through calendar and frame correction the CGCS2000 coordinates of control point are obtained. It is found that the corrected coordinates have the same precision as the traditional adjustment coordinate. On such a basis, the authors put forward an idea of using precise point positioning method to obtain CGCS2000 coordinates and pointed out the items deserving attention in using this method, and the application range of this method.

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    Seismic data separation of simultaneous source based on an improved iterative denoising method
    Jian-Hong GUO, Jing-Wang CHENG, Zhi-Ruo CHEN, Bing YANG, Hao YAN
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1054-1063.   DOI: 10.11720/wtyht.2019.0044
    Abstract   HTML ( 6 )   PDF (10090KB) ( 463 )

    Compared with single source acquisition method,simultaneous source acquisition technology can greatly increase field acquisition efficiency,and the separation of blended data is the key.When pseudo-segregated records of mixed simultaneous source data are sorted from common gathers to other gathers,the seismic signals of secondary sources show random noise,which can be separated by iterative denoising method.In this paper,the traditional iterative prediction denoising method is improved by adding the last separation result before each denoising to increase the stability of the iterative denoising,and combining with Multidirectional Vector Median Filtering to remove random noise.Through the separation test of simultaneous source mixed data of theoretical model,it is shown that the proposed method has better separation effect and is more robust,and can be operated under the condition of different parameters and maintain certain stability.Finally,the method is applied to the separation of Simultaneous Source Marine Line data,and a better separation result can be obtained.The method has practical application value.

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    A first arrival pickup method of micro-seismic event based on statistic energy ratio using varied time window with double constraints
    Wei SHI, Chun-Hua LIN, Wei-Hong WANG, Yun-Lu GAO
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1064-1073.   DOI: 10.11720/wtyht.2019.0065
    Abstract   HTML ( 6 )   PDF (0KB) ( 259 )

    The first arrival of seismic data is a key step of data preprocessing in seismic exploration.In the development of unconventional oil and gas reservoirs,surface microseismic monitoring technology is widely used.The focus of the work is to obtain the source location information generated by hydraulic fracturing,that is,the location of the microseismic source.For the microseismic source location, the initial picking of microseismic events is a key step,and the accuracy of the picking results directly affects the positioning accuracy of the microseismic events and the interpretation of the final results.However,in the actual seismic data,the signal-to-noise ratio of microseismic data is generally low,and it is difficult to obtain more accurate first arrival results.At present,the picking up of the first arrival wave of the microseismic is mainly divided into two methods:manual picking and computer automatic picking.The manual picking has the characteristics of high accuracy,but the workload is large,time-consuming and laborious.Aimed at picking accuracy of the first-arrival wave of seismic data and the anti-noise performance of the method,this paper makes improvement on the basis of the statistical energy ratio method of transforming time window,and sets the threshold value R while applying statistical law to obtain the superiority of high credibility.Combined with the value of picking range constraint Z and a variety of picking strategies,the first-arrival wave pick-up of the seismic record is finally achieved.The method was used to pick up the 3D seismic data of a work area in Songliao Basin and the hydraulic fracturing ground microseismic monitoring data of a horizontal well in Songliao Basin.The picking effect was obtained and the practicability of the method was verified.In summary,the method has achieved good pickup results in both the theoretical data of different signal-to-noise ratios and the application of actual data,and has strong anti-noise performance.

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    Seismic imaging of small-scale geological body using diffraction wave based on SVD algorithm
    Jun XU, Bin LIU, Qing-Xian ZHAO
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1074-1082.   DOI: 10.11720/wtyht.2019.1306
    Abstract   HTML ( 6 )   PDF (0KB) ( 342 )

    Diffraction originating from small-scale bodies is treated as noise in routine processing;however,it contains much information about the small-scale geological bodies,which may improve the resolution of the image.The first step of diffraction imaging is separating diffraction from the full record,since the energy of the diffraction is much weaker than the reflection.In this paper,the authors studied diffraction imaging which was separated directly on shot gather by using SVD algorithm.Compared with other separation methods,the theory and achievement of the separation directly on shot gather are easier.Numerical results show that SVD can separate diffraction from the full record well,even when noise is added to the data.The key of the method is to solve the problem as to which parts of the singular values should be intercepted while the remains could be used to reconstruct the wave-field,which requires testing various kinds of data.The results of the diffraction wave imaging are useful for the identification of small-scale geological bodies,and integrating diffraction wave imaging results with full wave imaging results can lead to a better interpretation.

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    A denoising method for microseismic signal based on the ensemble empirical mode decomposition of sample entropy threshold
    Ya-Juan WANG, Huai-Liang LI, Xian-Guo TUO, Tong SHEN
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1083-1089.   DOI: 10.11720/wtyht.2019.0196
    Abstract   HTML ( 3 )   PDF (0KB) ( 347 )

    It is inevitable to mix up non-stationary random noise in the process of microseismic signal acquisition.However,the practice shows that the traditional linear filtering and spectrum analysis methods are not idealistic for this mixed signal.In view of such a situation,this paper presents a new method to suppress nonstationary random noise.Firstly,the Ensemble Empirical Mode Decomposition (EEMD) is carried out for noise-containing microseismic signals,and a series of Intrinsic Mode Functions (IMF) with different frequencies components are obtained.In order to accurately identify the signal and noise in these IMF components,the authors calculated the sample entropy of each IMF in this paper.The threshold value of sample entropy was used to extract the IMF components conformable to the characteristics of microseismic signal,and these IMF components are reconstructed in order to suppress random noise.The proposed method has been applied to simulated data and measured microseismic data,and it is indicated that the method has ideal effect for noise reduction.

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    Gravity interface inversion method based on three-dimensional seismic peeling and its application
    Tao GUO, Jia-Shan HU, Ke-Min YIN, Shu-Hua WANG, Guo-Zhi FENG, Hui-Zhen YU
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1090-1096.   DOI: 10.11720/wtyht.2019.1475
    Abstract   HTML ( 6 )   PDF (0KB) ( 370 )

    The quality of seismic data is poor and imaging is difficult in case of deep layers because of complex near-surface and underground geological structural conditions in western exploration area,and the structure attributes of deep strata are difficult to be identified only by seismic data due to the inherent non-unique problem and the low resolution problem.The gravity interface inversion method based on 3D seismic stripping was adopted in this study,with the addition of drilling-geological data constraints,which can carry out gravity field source separation by means of forward "stripping" under the seismic structural interface constraints,and then the method could carry out interface inversion for target gravity anomaly.The popular frequency domain Parker-Oldenburg iterative algorithm was adopted in the forward inversion stage,which guaranteed the fast and stable convergence of the inversion.The results show that the three-dimensional seismic peeling method can effectively peel off the high-frequency signals,achieve the accurate acquisition of the gravity anomaly caused by the geological target body and calibrate the deep interface accurately.Deep structural interface inversion was carried out in eastern Junggar basin,which proved the method is an effective method for studying deep geological targets.

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    Forward analysis of array laterolog and rapid correction of environmental factors
    Jin FENG, Xiao-Wei NI, Qing YANG, Yao GUAN, Di-Ren LIU
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1097-1104.   DOI: 10.11720/wtyht.2019.0095
    Abstract   HTML ( 2 )   PDF (0KB) ( 310 )

    Resistivity logging data constitute an important basis for qualitative division of oil and gas reservoirs and quantitative calculation of oil saturation. However, resistivity logging data are vulnerable to environmental factors, which results in distortion of resistivity logging data. Taking array laterolog instrument as an example and based on finite element numerical simulation method, te authors studied the influence of borehole, surrounding rock and mud intrusion on its response. The results show that MLR1, MLR2 and MLR3 are obviously affected by borehole diameter when the borehole diameter is greater than 8 minutes, MLR4 is basically not affected by borehole diameter, and EALT results in high resistance mud environment are seriously distorted. MLR1, MLR2, MLR3 and MLR4 are seriously affected by the thickness of the layer when the thickness of the layer is less than 0.4m. The larger the difference of resistivity between the surrounding rock and the target layer, the greater the influence of ELAT response. When the invasion radius is less than 30 minutes, R1-MLR3 is greatly affected. When the ratio of formation resistivity to invasion zone resistivity reaches 5,10,100, the apparent resistivity distortion can be higher than 50%. Based on forward analysis, the authors drew the correction chart of EALT wellbore, surrounding rock and mud invasion and propose a fast correction method for the complex correction chart of surrounding rock, which can provide some reference for the correction of environmental factors of EALT logging data.

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    The evaluation method of reservoir parameters based on the rock's electrical parameter dispersion properties
    Zhan-Shan XIAO, Yun-Sheng ZHAO, Bao-Cheng ZHAO, Qiang LI, Hai-Tao HU, Kun SHAO, Chun-Ming YAO
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1105-1110.   DOI: 10.11720/wtyht.2019.0233
    Abstract   HTML ( 5 )   PDF (1771KB) ( 396 )

    A new rock electrical dispersion characteristic parameter dispersion rate P is constructed based on physical mechanism of rock electrical parameters dispersion characteristics. By comparing the electric dispersion experimental analysis of reservoir rocks and artificial rock samples under simulated reservoir conditions, the response relationship between the dispersion rate P and the reservoir parameters such as saturation, porosity, permeability and cation exchange capacity Qv is established. The research shows that the dispersion rate P has a good linear relationship with water saturation and porosity. The dispersion rate P has a good power-law relationship with the permeability and cation exchange capacity Qv. Compared with the modulus dispersion rate PZ and the real part dispersion rate PR, the phase dispersion rate Pφ and the imaginary part dispersion rate PL can characterize the electrical dispersion of the rock better. The dispersion rate P and reservoir parameters have good correlation and indication, and can be used as reservoir evaluation parameters for resistivity spectrum logging.

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    The applicability of different sources DEM data in median region terrain correction of gravity in high mountain areas
    Sheng-Rong LIU, Peng GAO, Tao GENG, Wei-Li GUO, Hui DU
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1111-1118.   DOI: 10.11720/wtyht.2019.0126
    Abstract   HTML ( 2 )   PDF (5039KB) ( 542 )

    Taking the Xiarihamu mining area in Qinghai Province as an alpine experimental area, the authors used the high-precision 1:2,000 DEM data to make a comparative analysis of the vertical accuracy of 1:50,000 DEM data, Aster DEM data and Pleiades DEM data as well as the applicability of these data in median region terrain correction of gravity under the complex terrain conditions such as high mountain areas. The results show that the accuracy of Pleiades DEM is the highest, that of 1:50,000 DEM possesses the second place, and hat of Aster DEM is the lowest under the complex terrain conditions of high mountainous area. The Pleiades DEM data have good applicability in median region terrain correction of gravity scale of 1:50,000 or less, and the 1:50,000 DEM data have good applicability at a scale of 1:200,000 or less, but the Aster DEM cannot meet the accuracy requirements at a scale of 1:200,000 or more.

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    Discussion on the attributes of the phases in Tube wave filed
    Hui HE, Na DUAN, Wen-Qi GAO
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1119-1122.   DOI: 10.11720/wtyht.2019.0030
    Abstract   HTML ( 3 )   PDF (3870KB) ( 418 )

    The Tube wave detection is a new downhole geophysical technique used in geological engineering in recent years.Based upon the observed data of tube waves,this paper tries to analyze the kinematic characteristics of the different phases in the Tube wave field.The results from this analysis show that the technique not only can detects t the integrity of a downhole,but also can map the variation of the geological structure along the downhole by the traveltimes of refracted Tube wave from the drill wall.Meanwhile,the unknown phases R * is found in this study,the phase R * should be the twice reflection of phase R1 acoording to the twice traveltimes of the original reflections.

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    An analysis of soil nutrient status of kiwifruit orchard in Qianjiang, Chongqing
    Ming-Shu YAN, Chun-Mei WU, Li MENG, Xiang-Lun DING, Pan DONG, Hai DENG, Jia-Li LEI, Yuan-Yuan GONG, Li-Ran BAO
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1123-1130.   DOI: 10.11720/wtyht.2019.0135
    Abstract   HTML ( 1 )   PDF (693KB) ( 474 )

    In order to fully understand the nutrient status of kiwifruit orchard soil in Qianjiang District of Chongqing City, the authors systematically analyzed soil pH, organic matter, cation exchange capacity, and total and effective content of plant nutrient and life elements in soil . The results show that the soil in Qianjiang kiwifruit orchards is moderate to acidic, rich in organic matter, with an average of 2.89%, but the cation exchange capacity of soil is relatively low, with 75% of the total samples in grade 4 (middle-poor) and 5 (poor) levels. The values of nitrogen, phosphorus and potassium in the orchard soil are generally good, but some of the samples have exceeded the suitable growth range of kiwifruit. The content of medium element Ca is deficient, while the content of medium element Mg is abundant in many areas. The content of trace elements Fe, Mn and Mo varies greatly in different sampling points. The soil in the study area is rich in Se on the whole. Based on the above analysis, it is suggested that, in the future fertilization process, more organic fertilizer should be applied to improve the content of organic matter and soil cation exchange capacity, the application of nitrogen fertilizer should be maintained or appropriately increased and the application of phosphorus and potassium fertilizer should be controlled. In addition, whether fertilization is necessary for tackling the deficiency of trace elements in soil needs further study.

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    Chemical composition analysis and soil geochemical characteristics of Mopan persimmon in Panshan, Tianjin
    Wei-Xing WANG, Shu-Ping CAO, Gong-Ke LI
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1131-1137.   DOI: 10.11720/wtyht.2019.0020
    Abstract   HTML ( 2 )   PDF (1442KB) ( 522 )

    Persimmon is a traditional fruit tree species in Jizhou District of Tianjin. The variety of persimmon planted in the surrounding area of Panshan in Jizhou District is Mopan persimmon. Mopan persimmon is named for its origin in Panshan, a scenic tourist resort. In this paper, the quality indexes of persimmon and the geochemical characteristics of soil in Panshan were studied. According to the results obtained, the average ash content of Panshan Mopan persimmon is 0.38 g/100 g, the average fat is 0.20 g/100 g, the average crude fiber content is 0.67%, the average content of beta-carotene is 77.27 μg/100 g, the average moisture content is 77.92 g/100 g, vitamin C is 25.80 mg/100 g on average, the average total soluble sugar is 14.81%, and the average protein content is 0.63 g/100 g. K, N, P and S, Ca , Mg, which belong to large and medium nutrient elements in soil, are the most abundant elements in the fruit of Mopan persimmon; Mopan persimmon is mainly distributed in and around Panshan granite rock mass; the values of MgO, K2O, Mo and F in the surface soil of the production area are significantly higher than the background values of Tianjin soil; the average content of SiO2 in root soil from top to bottom is higher, and sandiness of soil is beneficial to persimmon tree growth; the average content of K is higher, while the average content of N, P and Corg in root soil is deficient or deficient; soil acidity and alkalinity environment of surface soil and root soil in Mopan persimmon producing area is more suitable for persimmon tree growth. The correlation between root soil elements and fruit quality shows that the superiority of SiO2, Mo, P and K2O content in soil of production area provides favorable conditions for the improvement of nutrient quality of fruits, such as beta-carotene, VC, and protein, which is conducive to the formation of high quality fruits.

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    Distribution characteristics of Se speciation of alkaline soil in eastern Qinghai
    Ya-Feng ZHANG, Guo-Wen MIAO, Qiang MA, Bing-Yan JI, Guang XU
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1138-1144.   DOI: 10.11720/wtyht.2019.0053
    Abstract   HTML ( 1 )   PDF (2604KB) ( 537 )

    In this paper, the Se speciation characteristics of alkaline natural Se-rich soil in eastern Qinghai were studied by collection and analysis of surface soil samples with different Se values. The results show that Se exists in the form of effective state, including water soluble state and ion exchange state, which accounts for 6.38% of the total Se. Carbonate state and iron and manganese oxidation state account for 4.53% of the total Se. The values of both of them are higher than the proportion of corresponding form in some acidic and Se rich soils in China. The unusable state Se, including strong organic state, humic acid binding state and residue state , accounts for 89.09% of the total Se, lower than the level of non-available Se in some acidic and selenium rich soils. The feature of selenium rich soil in Qinghai Province exhibits higher available state, higher potential available state and lower unusable state. In addition to the iron and manganese oxidation state, the values of 6 forms of Se are positively correlated with the total Se. The values of total Se, humic acid binding Se and residue Se are significantly negatively correlated with pH value, thus the total Se and the non-available Se decrease with the increase of soil alkaline environment.

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    The realization of applying 3D frequency stepped ground penetrating to the detection of asphalt layer thickness
    Ze-Shan XU, Jiang-Tao ZHOU, Si-Xin LIU, Xian-De ZENG
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1145-1150.   DOI: 10.11720/wtyht.2019.0005
    Abstract   HTML ( 2 )   PDF (4282KB) ( 645 )

    Because of its non-destructive and high-resolution characteristics, ground penetrating radar technology has been widely used in road nondestructive testing in recent years. The ground penetrating radar currently used for road asphalt layer thickness detection is mainly a high frequency single channel antenna above 1 GHz; compared with the traditional core sampling, it has the advantages of non-destruction and high efficiency, but its detection coverage is small, and there is a problem of line generation. In order to realize the full coverage non-destructive testing of asphalt layer thickness in the completion acceptance of Lanzhou municipal road project, the authors used three-dimensional stepped frequency space-coupled ground penetrating radar combined with the core thickness to verify its reliability in asphalt layer thickness detection. The authors analyzed the working principle and depth resolution of the stepped-frequency ground penetrating radar system and, based on the experimental results and acceptance examples of the three-dimensional stepped-frequency ground penetrating radar, consider that it is suitable for road asphalt layer thickness detection, and has the characteristics of intuitiveness, high efficiency and high resolution.

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    The mine drilling resistivity method used to determine the development height of the "three zones" top interface of the mining face
    Guo-Cai YAN
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1151-1156.   DOI: 10.11720/wtyht.2019.0023
    Abstract   HTML ( 2 )   PDF (2974KB) ( 279 )

    The influence range of the mining work on the overlying rock strata is directly related to the safe production of the coal mine. In order to accurately determine the development height of the "three zones" top interface of the mining face, the author used the mine drilling resistivity method to detect the different depths of the mining face at different periods. The sectional view was used to explore the apparent resistivity cross value between different mining positions and the reference position. The deviation rate curve of the "three zones" development was analyzed. The development height of the top interface of each zone was determined. And the results were compared with the calculation results by the derivation formula of the double-end plugging segmental water injection method. The results show that the borehole resistivity method has strong resistance to the complex environment of the underground, and has good coupling with the coal-rock layer. The height of the "three-band" top interface determined by the difference of apparent resistivity is higher. The determinations by the deviation rate curve are as follows: The development height of the top of the falling zone is 29.6m, the development height of the top interface of the fracture zone is 47.8m, and the development height of the top of the curved zone is 71m. The results are similar to those of the double-ended plugging water injection, and the deviation rate can be clearly distinguished. The interface of the three belts improves the resolution of the height detection of the "three belts" top interface, and has a high promotion and practical value.

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    The application of electrical method to tracking underground river of reservoir dam area
    Zhan-Jun WANG
    Geophysical and Geochemical Exploration. 2019, 43 (5): 1157-1162.   DOI: 10.11720/wtyht.2019.1317
    Abstract   HTML ( 6 )   PDF (3522KB) ( 542 )

    In the primary design stage of a certain reservoir in Guizhou Province, geologists found that intensively developed karst has great influence on reservoir leakage. The author discussed the experience of tracing underground river and seepage channel using charging method and high density resistivity method, which has been proved through practical connection test and water level change.

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