地质科技通报

Diagenesis of the Ordovician Carbonates in Bozhong Depression,Bohai Sea Area

Zhao Guoxiang, Wang Qingbin, Jin Xiaoyan, Wang Feilong, Liu Xiaojian, Bai Bing

2015, 34(5): 1-7.

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There is long geological reconstruction of Ordovician carbonates in Bozhong Depression after its deposition.Different diagenetic transformation makes reservoir very complex,so identifying the different diagenetic environment has certain significance for the buried hill reservoir prediction.By using normal thin-sections,cast thin-sections,scanning electron microscope and cathodoluminescence,this paper analyses the main diagenetic environment in the research area through the normal seawater,atmospheric freshwater and burial diagenetic environment.The pore types are dominated by secondary pores caused by dissolution and fracture.The reservoir physical properties are characterized by medium reservoir with strongly heterogeneity.The carbon and oxygen isotopic analysis and inclusion analysis of carbonate reservoir,based on the regional tectonic evolution and microscopic characteristics,shows although dissolution may occur in atmospheric freshwater and burial diagenetic environment,the main influential factors were hypergene karstification during the Paleozoic to Mesozoic time.The long time leaching dissolution improves the reservoir physical properties,but the dissolution under burial diagenetic environment can be limited for shaping the reservoir physical properties.The primary factor for lowering the Ordovician reservoir physical properties should be the large scale cementation in deep burial environment during Neocene.

Development Characteristics of Sedimentary System and Control Factors Analysis of the Third Member of Liushagang Formation in Eastern Wushi Depression,Beibuwan Basin

Zhang Jianxin, Hu Desheng, He Weijun, Dang Yayun, Liu Ping

2015, 34(5): 8-15.

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Beibuwan Basin is one of the major oil-gas basins of the northern South China sea,where the third member of Liushagang Formation in eastern Wushi Depression is the main oil and gas exploration target layer.Therefore,its sedimentary model and distribution of sedimentary microfacies are the keys for the oil-gas exploration in this area.Through the comprehensive research of core,drilling,seismic data,this paper analyzes in depth the fault activity and its space distribution and characteristics of the sediment source system and the spatial distribution of the sedimentary micro-facies,and discusses the inter restricted relationship of tectonics and sedimentation.The results show that the area was in atypical shallow water delta environment when the third member of Shaliugang Formation was deposited,with its material source provenance from Qixi uplift.On the whole,the area should belong to the traction current deposit characterized by near source,poor sorting,frequent facies change and strong block partition and the sedimentary microp facies is dominated by underwater distributary channels.The spatial distribution of the sedimentary body is mainly controlled by the 6 NE-SE normal faults developed in the sedimentary period of the third member of Liushagang Formation.Faulting intensity difference controls the gully-gully geomorphology characteristics,distribution of source water system and provenance forward distance in this region,leading to the obvious difference of the various distribution channels.The gullies controlled by the two faults(F₃ and F₄) are relatively flat and the underwater distribution channels are promoting relatively far.This is an important exploration direction in eastern Wushi Depression.

Summary of Research Methods About the Sequence Stratigraphy of the Fine-Grained Rocks

Wu Jing, Jiang Zaixing, Wu Minghao

2015, 34(5): 16-20.

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To analyze the distribution rule of high quality reservoir of fine grained rocks(FGR)of unconventional petroleum in the formation,domestic and abroad status of FGR sequence stratigraphy are researched and discussed.Resultsshow that a variety of methods are put forward to solve the difficulty of FGR sequence stratigraphy by the former scholars.Mineral composition,lithology,geochemistry,logging curves and bioturbation have been used to study the sequence stratigraphy of FGR,limited to the recognition of third-and fourth-order sequences.Division methods of the fifth-order sequence(parasequence)are proposed only by few scholars for FGR.It is identified and divided through the analysis of logging curves and organic geochemistry.This paper argues that the deep analysis of FGR sedimentary characteristics(lithofacies and causes)is the basis to solve its sequence division.Third-and fourth-order sequences division can be divided into two steps,vertical integrated division and transverse contrast tracking.In the stratigraphic framework of third-and fourth-order sequences,according to the lithofacies and in combination with the changes in mineral compositions,contents and ratios of geochemical elements,logging curves,and wavelet values,multi-method analysis and mutual verification are implemented in the division of parasequence.Eventually,from shallow water to deep water,from conventional glutenite to unconventional FGR,sequence framework can be built with all levels throughout the whole basin.

Nummulite Limestone Reservoir Sequence and Sedimentary Feature,Pelagian Basin

Li Juan, Wang Tianqi, Sun Songling, Gou Yingchun, Jia Yirong

2015, 34(5): 21-26.

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Nummulite limestone of El Garia Formation,Lower Eocene is the main reservoir of Bouri Oildfiled in Sabratah Basin,North Africa,which produces 85 % of oil in the oildfiled.This paper studies the sedimentary model and sequence stratigraphy of the Nummulite limestone based on the comprehensive analysis of seismic,drilling and well logging data.The results show that El Garia Formation is composed of one dependent SQ1 of three level sequence,the superimposition of one transgressive system tract and one highstand system tract.SQ1 can be subdivided into four 4-level sequences according to its base level cycle and superimposition,in which Nummulite limestone is developed in S1-1 sequence.Platform gentle slope model is found in the deposition process of El Garia Formation,.Because of the impact of the ancient uplift and water depth,the bioclast bank of Nummulite is usually distributed in dots in the high position of the ancient structure or in bands and apron belts along the slope margin,showing strong heterogeneity

Geochemical Characteristics and Tectonic Setting of A Zhalu Granite in Ailaoshan Structure Magmatic Belt,Western Yunnan Province

Zhao Yanan, Xiao Yuanfu, Li Hongxiao, Xiao Ruiqing, Zheng Lang, Shen Lijun

2015, 34(5): 27-30.

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A Zhalu granite is located in the Ailaoshan structure magmatic belt.The granite is studied in the aspects of its geochemical characteristics and tectonic setting.The study shows that its distribution is obviously controlled by faults and the rock is characterized by shallow intrusion.Locally,the rock body is found with visible schist and mylonite of synantexis metamorphosed in the later period..The A/NCK of A Zhalu granite is mostly more than1,belonging to aluminum saturation.The granite has the characteristics of rich Si and K,low Ca,and poor Fe,Mg and Ti,indicating that it belongs to the high K Ca alkaline series.The geochemical analysis of major elements,trace elements,and rare elements show that the rock was formed in the arc continent collision stage of late stage orogenic collision.

Analysis of REE Geochemical Characteristics and Sedimentary Environment of the Early Cambrian Black Rock Strata in Daba Mountain

Ling Sixiang, Wu Xiyong, Ren Yong, Li Xiaoning, Wang Ganggang

2015, 34(5): 31-37.

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In this research,ICP-MS method was used to determine the abundance of REE and some trace elements,e.g.,V,Ni,Cr,U,Th,Zn,and Co,of black rock strata of Shuijintuo Formation from Early Cambrian in Chengba rift belt,Daba Mountain.By analyzing these elements,we researched the REE geochemical characteristics of black rock strata and their sedimentary environment.The results show that the black rock strata displayed LREE-enriched type in study area,were characterized by obviously negative Ce anomalies(δCeN=0.47-0.94,δCeS=0.46-0.91)and negative Eu anomalies(δEuN=0.27-1.03,δEuS=0.42-1.57),and that the ratios of U/Th range from 2.52 to 67.51,the ratios of V/(V+Ni)=0.65-0.98,Sr/Cu=5.83-27.96,V/Cr=1.35-17.79,and δU=1.77-1.99 were in relatively high level.The analysis of the NASC-normalized REE-patterns,La-Ce diagram,Zn-Ni-Co triangular diagram and La/Yb-REE diagram reveals that the black rock strata were formed in a dry,anoxic and shallow marine shelf and slope marginal environment belonging to passive continental margin affected by hydrothermal fluids.

Characteristics of Sequence Stratigraphy and Sedimentary Facies in the Lower Xinhe Formation of Xiaohu Sub-sag,Yabulai Basin

Shi Yingtao, Liao Yuantao, Tang Jianrong, Wei Jun, Cao Haiyang, Zhang Chengcheng

2015, 34(5): 38-45.

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The Lower Xinhe Formation of Xiaohu sub-sag,Yabulai Basin is the key exploration horizon in Yumen Oilfield.Commercial oil flows found in well YT6,show a good exploration prospect.So,under the sequence framework,well understanding the distribution of contemporaneous sand bodies is favorable to the further exploration and exploitation.This paper aims to employ the classic sequence stratigraphy,to elaborately analyze the sequence characteristics,sedimentary facies types,and sediment evolution and distribution,and discusses the distribution of favorable sedimentary reservoir,based on the data of drilling cores,loggings and seismic data.The results show that the Lower Xinhe Formation develops a complete third-order sequence.Fan delta,braided river delta and lacustrine facies are developed in the Lower Xinhe Formation.The palaeogeography of the Lower Xinhe Formation is characterized by a clear difference between the southern part and its counterpart of the basin.Fan delta front is located along the south steep fault belt and braided river-delta front is developed in the northern and northwestern gentle slope,with lacustrine sediments in the central lake.From the period of lowstand system tract to highstand system tract,sedimentary characteristics and the sedimentary facies distribution are both correspondingly different in different stages.Overall,the changes of the depth of water from shallow to deep,and then to shallow cause the sedimentary area gradually to enlarge,and fan delta,braided river delta first to progradate,then retrogradate,and finally progradate.The analysis indicates that the distributary channels of highstand system tract in the northwest of YT6 well as favorable reservoir are the future exploration targets in the study area.

Geochemical Characteristics and Tectonic Settings of Late Carboniferous Intrusive Rocks from North Tarshan Area in Junggar,Xinjiang

Li Gaojie, Pan Shuo, Hou Yu

2015, 34(5): 46-52,65.

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As an important part of the Central Asian Orogenic Belt,the North Tarshan area in Xinjiang provides an ideal place for studying the tectonic evolution of the Junggar region because of its distinctive location.The Late Carboniferous intrusive rocks in the area consist of a complex series of rock sequence showing distinctive features of crust-mantle hybrid,with the early stage rock body dominated by diorites and the late stage rock body predominated by granitoids.This set of rock sequence is produced by the evolution of primitive magma in different stages.All geochemical characteristics,along with Rittman index σ<3.3,A/CNK<1.1,P₂O₅<0.65%,Fe₂O₃/FeO>0.4,enrichment in LILE and depletion in HFSE,are typical of I-type granitoids.However,further studies show the late plutons characterized by the rich silicon and alkaline,high potassium,low CaO,FeO,MgO,are alkaline granites,indicating the area has finished environmental evolution from the extruding collision to the post-collisional setting at the end of late Carboniferous and should be formed in a period about or ahead of(290.4±3.2)Ma.The findings will supply crucial evidences to explore the tectonic setting cycle of the Junggar region and the Central Asian Orogenic Belt.

Implications of Soluble Hydrocarbons in Cold Spring Water on the Formation of Gas Hydrate in Wuli Permafrost,Qinghai Province

Wang Jinshou, Pan Tong, Ceng Xiaoping, Chen Jing

2015, 34(5): 53-57.

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Wuli permafrost is located in the Qinhai-Tibetan Plateau,with low latitude and high elevation(4 600-5 300m).This paper describes the study of the gas source conditions for gas hydrate formation in the area.Several cold springs(Reisen)are developed along the fault in the permafrost area.For the study,500 ml fresh water of the cold springs was collected,sealed and sent to the laboratory for gas chromatography analysis.First of all,gas in the dissolved hydrocarbon was extracted in vacuum and 60℃ constant temperature conditions,and CO₂ was absorbed by ρ(NaOH)=300g/L alkali liquor,while the remaining gas was expelled through the lye to the upper airway,and transferred to another place after the volume was measured.Then appropriate volume of prolapse is injected into the dissolved hydrocarbon according to its content,and calibrated chromatography,a single point external standard quantification.It is detected in the result that the CH₄ content in cold spring water is generally around 223.60-1 097.30 μl/L,up 1 113.21 μl/L.The favorable source rocks are mainly Late Permian Nayixiong Group of interactive marine and terrestrial coal-bearing clastics and the Late Triassic clastics of Bagong group.Multiple coal seams and dark carbonaceous shale contained in the former strata are considered to be the important parent materials for the gas hydrate formation.Resultsof this study suggest that the region has potential conditions for the gas hydrate entrapment and accumulation.

Reviews on the Hydrothermal Alteration of Carbonate Reservoirs

Hu Zuowei, Li Yun, Han Xin, Huang Sijing, Li Beikang

2015, 34(5): 58-65.

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The research of the hydrothermal alteration is an important part of the genetic mechanism of the high-quality carbonate reservoirs in recent years.Currently,hydrothermal dolomitization and hydrothermal leaching dissolution with the remarkable oil and gas reservoir significance are two most important geological processes in the hydrothermal alteration.Based on the analysis of a large number of publications,this paper has systematically summarized the processes,sizes,problems of two types of the typical hydrothermal alteration(hydrothermal dolomitization and hydrothermal leaching dissolution)of carbonate reservoirs.Further discussions on the hydrothermal alteration of carbonate reservoirs in this paper not only show the ambiguity and multiplicity on the research of the models of the hydrothermal alteration,but also offer practical guidance for the better application and improvement of the currently models of the hydrothermal alteration in the future.

Advances of Reservoir Evaluation Researches

Chen Huanqing, Ding Chao, Du Yijing, Wang Jue

2015, 34(5): 66-74.

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The final aim of reservoir researches is the classification and evaluation of reservoirs in accordance with geological reality.The classification and evaluation will directly guide the oil and gas exploration and development,so the result of reservoir evaluation always is central point of all researchers.With the overview of the present reservoir evaluations home and abroad as well as the author's own practical researches,this paper summarizes eleven kinds of reservoir evaluation methods such as geological empirical approach,weighted analysis,analytic hierarchy process,fuzzy mathematics,artificial neuron of neural network method,fractal geometry,variation function,cluster analysis methodology,gray correlation method,logging methods and seismic techniques.When discussing the advantages and disadvantages of these methods,the paper suggests that the data selection,the evaluation parameter selection and the rational confirmation of the evaluation results should be key points in the reservoir evaluation.At the same time,the paper points out the problems and the development directions of reservoir evaluation researches.

Genetic Analysis of the Beach Facies Reservoir in Feixianguan Formation in Tieshan,Northeastern Sichuan and Its Peripheral Area

Wu Bin, Xiao Shihong, Yin Nanxin, Liao Jinhua, Li Xiangming, Gong Qisen, Wang Jinxi

2015, 34(5): 75-80.

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The study adopts macro and micro methods to address the complex origin of beach reservoir in Tieshan and its peripheral area,northeastern Sichuan.The main reservoir space types are moldic,intragranular solution pores,intercrystal pores and residual intergranular pores.The reservoir properties are relatively poor,dominated mainly by secondary pores.while porosity/permeability relationship is not unique,which may be caused by the fissure-pore and pore-fissure types with low porosity and low permeability.The origin of Feixianguan beach reservoir is controlled together by eustatic sea level,tectonism,burial solution.Oolitic beach is distributed along the margin of platform.Due to eustatic cycle,oolitic beach experienced multi-episodic exposures,which was dissolved by atmospheric water.Since porosity and permeability were decreased by compaction and multi-episodic cementation,secondary pores flourished with the burial solution and tectonic fluctuation,which dramatically boosted the reservoir property.

Continental Shale Gas Reservoir Sensitivity Experimental Research of Chang 7 of Yanchang Formation in Xiasiwan Area

Wu Chunyan, Shen Ying, Cheng Yuqun, Mao Zhongyuan, Jia Pengtao

2015, 34(5): 81-85.

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An experimental study has been conducted on sensitivity of the continental shale gas reservoir of Chang 7of Yanchang Formation in Xiasiwan area,using X-ray diffraction,field emission scanning electron microscope,nitrogen adsorption and core displacement experiment.The results show that the reservoir is characterized by medium weak or weaker salt sensitivity,water sensitivity and alkali sensitivity,weak-no acid sensitivity and medium to strong or strong stress sensitivity.The main factors affecting the reservoir sensitivity are the mineral components,reservoir property and reservoir pore structure.Due to the particularity of shale reservoir,some key experimental technologies and methods were improved in the sensitivity experiments.①The complete pore throat size distribution curve was formed by combining the mercury injection capillary pressure curve with the nitrogen adsorption method to obtain BJH pore size distribution curve function.②The sample oil removal in the sensitivity experiments was implemented by conventional washing oil and high temperature(150-200℃)baking method.③The pulse gas permeability tester was adopted,which is most suitable for shale gas reservoir sensitivity experiments at present.The permeability values before and after the sensitivity experiment were obtained,using the gas displacement method instead of the conventional liquid displacement method.The sensitivity of the reservoir characteristics data of the shale was obtained by the improved sensitivity experiment,which satisfies the purpose and requirements of this experiment.

Molecular Dynamics Analysis of Shale Reservoir Gas-Solid Adsorption Based on the Lattice Theory Model

Yin Shuai, Ding Wenlong, Liu Jianjun, Zhao Jinli, Lan Baofeng, Cao Anqi, Zhao Wei

2015, 34(5): 86-90.

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This paper describes pure methane's adsorption characteristics based on the lattice theory model.The model can make a difference based on different assumptions.This model has a high precision on predicting the adsorption quantity with the absolute error of less than 0.0042 mmol/g.The determined parameters such as Г₀ and ε_s can be used to indicate the influence of temperature-pressure of methane adsorption characteristics and the development degree of micropores.The value of |ε_s| decreases with the increase of temperature,with the relationship being almost linear, Г₀ <Гmaxand Г₀ can roughly characterize the molecular adsorption state,with the value of Г₀ and |ε_s| of methane adsorption in the shale much smaller than that of the activated carbon rich in micro-pores.The discussion of the linear relationship of Y and X and the calculation of the value of ε_a show that the value of |ε_a| is smaller than |ε_s|, within the scope of P and T in this paper,|ε_a| gets alittle rise first and then decrease with the increasing temperature,at a lower temperature the ratio of ε_s and and ε_a is larger(7.05 times),but as the temperature increases,the ratio decreases and gradually becomes stable(3.37 times).The study of different types of shale on a wider scale temperature and pressure with this theory has a great significance for the shale microstructure characterization.

AHP Application to Shale Gas Exploration Areas Assessment in Sichuan Basin

Guan Quanzhong, Dong Dazhong, Wang Yuman, Huang Jinliang, Wang Shufang

2015, 34(5): 91-97.

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In order to analyze key factors of profitable shale gas exploration and development for shale gas exploration areas in Sichuan Basin,the theory of analytical hierarchy process has been used to establish an optimization hierarchical structure model of shale gas exploration area assessment:goal layer,criterion layer,sub-criterion layer and project layer.The model is established by four steps:building up a hierarchical structure model,constructing judgment matrix,making single hierarchical arrangement and its consistency test,and forming total hierarchical arrangement and its consistency test.The weight factors are computed for the assessment.The main factors for the shale gas exploration and development are:geological condition,development condition and support condition.Geological condition is the first factor for shale gas exploration area assessment and its weight is up to 0.637 0.Sub-criterion layer mainly contains 12 evaluation indexes:thickness,TOC,R_o,gas content,profitable space,burial depth.etc.Gas content,natural facture growth,pressure coefficient and market demand are the key indexes for shale gas profitable play assessment.Jiaoshiba and Changning shale gas areas are of high marks and are the most favourable areas for the shale gas development according to the evaluation index given for weighted summation method.It is suggested that the assessment method of "different levels,focus and orders" should be used in the shale gas exploration in order to avoid unnecessary loss.

Influence of Submarine Mud Diapirs（Mud Volcanoes）on Gas Hydrate Accumulation

Liu Jie, Sun Meijing, Su Ming, Yang Rui, Wu Nengyou

2015, 34(5): 98-104,119.

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There are close relationships between the submarine mud diapirs(mud volcanos)and their periphery gas hydrates orebody.The intrusion of gas-bearing fluid in the mud diapirs(mud volcanoes)can change temperature,pressure and geochemical characteristics of GHSZ,and thus should affect the formation and enrichment of gas hydrate.At the same time,as an important and effective migration channel type,the mud diapir(mud volcano)structure exerts methane which can also become an important gas source for gas hydrate.In addition,the mud diapir(mud volcano)have different effects on the formation and stability of the hydrate in the different evolution stages.The migration channel might not extend to the hydrate stability zone in the early stages of mud diapiric formation,resulting in insufficient supply of CH₄.This is conducive to the formation of natural gas hydrates in the middle stage,because of good matching in hydrate metallogenic conditions.The abnormal heat in the hydrate stability zone,caused by high temperature gas-bearing fluid from mud volcano eruption,may lead to the decomposition of hydrates in the late stage.Until the quiet period of mud volcano activity,hydrate can form the reservoir again.There are two models of the formation of gas hydrates within a mud volcano:low-temperature hydrothermal process dominated around the central part of the mud volcano and metasomatic process dominated at the peripherical part of the mud volcano.

Characteristics and the Main Controlling Factors of Micro-pore Structure of the Shale in Wufeng Formation-Longmaxi Formation in Jiaoshiba Area

Yang Rui, He Sheng, Hu Dongfeng, Zhang Hanrong, Zhang Jiankun

2015, 34(5): 105-113.

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Micro-porestructure is the key element influencing the storage capacity,permeability and determining whether the shale is of commercial value.Taking 15organic-rich shale samples from the Wufeng Formation-Longmaxi Formation of JY1 well as a target,this research studies the shale's pore volume,size and distribution by using total organic carbon,X-ray diffraction,high pressure mercury injection,helium porosity,low temperature N₂ adsorption and desorption technology and argon-ion polishing scanning electron microscope(SEM)combined with the the bitumen reflectance and natural gas carbon isotope date.Then this research also discusses the main controlling factors of the pore structure from both external and internal aspects.The research indicates that the pore types in organic-rich shale in the formation are mainly inorganic pores(intergranular,intragranular and inside pores),organic pores and microfractures.The results of mercury injection and adsorption experiments show that the shale pore structure is relatively complex as pores sized less than 50 nm are predominant and micropores occupy approximately 65% of the total surface area is provided by micropores,while about 57% of the specific pore volume is provided by mespores,dominated by parallel plate with all sides open exixting simultaneously with a variety of other forms of pores in the shale.During the process of extrusion,uplifting and erosion since Cretaceous,the change of tectonic stress or temperature and pressure may contribute to the formation of a large number of cracks.The thickness,distribution and the enrichment of organic cabon of the shale may be restrained by the difference of the sedimentary environment.Correlation analysis shows that specific surface area of micropores,mespores and volumes have strong relationship with total organic carbon content.The influence of clay minerals and quartz content on pore structure has reciprocal effect.When Rois less than 3.0%,specific surface area and volume present positive relationship,however,when it exceeds 3.0% the negative relationship is observed.It can be explained that the development of the nanoscale pore is restricted by thermal maturation,which results in the reduction of micropores.

Multifractal Characteristics of Metallogenic Elements of Pingguo Accumulated Bauxite in Guangxi

Ouyang Chengxin, Xi Xiaoshuang, Cao Jingya

2015, 34(5): 114-119.

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In western Guangxi the accumulated bauxite was taken as the study object.The method of moments is used to analyze the grade data of 144 421 samples collected from Taiping and Nadou ore deposits.Then the multifractal characteristics of aluminum,iron and silicon in accumulated bauxite are studied.Finally,the result illustrates that the grade distributions of aluminum,iron and silicon in Pingguo bauxite are in line with the model of multifractal obviously,and so this leads to the conclusion that the distribution of metallogenic elements of exogenic deposit is in line with the model of multifractal.The comparative analysis of the multifractal spectrum and parameters of aluminum,iron and silicon from Taiping ore deposit and Nadou ore deposit shows that aluminum is enriched in Nadou ore deposit and iron is enriched in Taiping ore deposit.The differences of multifractal spectrum parameters indicate the differences of grade distribution between the two ore deposits.This may be attributed to the different intensity of denudation acting on the accumulated bauxite.Accordingly,the trend of elemental detachment of the accumulated bauxite in the weather-worn environment is preliminarily discussed.

Analysis of Advantageous Minerogenic Conditions of Lacustrine Mudstone-Type Uranium Deposit

Song Ji, Jiao Yangquan, Wu Liqun, Wang Xiaomei

2015, 34(5): 120-126.

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In recent years,the uranium enrichment in the lacustrine dark mudstone of production grade,has been discovered in the Ordos Basin and Erlian Basin of China.The present paper describes the study of this lacustrine mudstone-type uranium deposit further by summarizing and analyzing the researches of black shale-type uranium deposits and the lacustrine mudstone-type uranium deposits in foreign countries combined with preliminary exploration on the Nuheting uranium deposits in the Erlian Basin and the uranium enrichment in southern Ordos Basin.The advantageous minerogenic conditions of the lacustrine mudstone-type uranium deposit are:①The existence of sufficient and sustainable uranium source.②High levels of adsorbents and reducing agents,with the adsorbents mainly including organic matter and phosphate,and the reducing agents mainly of organic matter and some sulfide represented by pyrite.③Low deposition rate and the longer anoxic sedimentary environment.④The mutation of the redox environment,the redox boundaries directly affecting the position of uranium mineralization.⑤Advantageous paleogeographic conditions,including relatively stable positive landform uplifting continuously and periodic alternating climate.

Soil Geochemical Anomaly Information Extraction and Prospecting Prediction of the Miegetan Gold Deposit,Northern Segment of the Dachang Gold Mine,Qinghai Province

Wang Faming, Zhai Yulin, Li Yanjun, Wang Fude, Wang Wen, Li Xiang, Ke Kunjia

2015, 34(5): 127-133.

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The Miegetan gold deposit is located in the north of the Dachang Gold Mine,north Bayan Har Orogen,Qinghai Province,China.The main ore-bearing strata are sandstone of the Triassic Bayan Har Mountain Group.With well developed thrust faults,the ore bodies are distributed along NW structural fractures,which control the occurrence.Hydrothermal alterations include silicification,pyrite,arsenopyrite mineralization and sericitization.The results of soil geochemical survey for Au,As,Sb and Hg show the anomalies are obvious and have a prominent concentration center.All anomalies with a NW distribution have a good registration.The peaks of content variation trend in the section correspond well with the orebodies.The prospecting model developed on this basis can thus direct the prospecting work.The prospecting target and metallogenetic prospective area are delineated according to the comprehensive analysis of the geological and soil geochemical characteristics of the Miegetan gold deposit to provide the reference for the Miegetan gold deposit even the periphery of core area in the Dachang Mine.

New Progress on the Chuquicamata Porphyry Copper Deposit,Chile

Liu Bin, Wang Yinhong, Wang Jianping, Zhao Zenan, Zhang Fangfang

2015, 34(5): 134-141.

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Chuquicamata copper deposit is the largest porphyry copper deposit in the world.The paper summarizes the regional geological setting of the deposit formation,and in more detail describes the deposit from the following aspects:the alteration features,mineralization stages,diagenetic age,mineralization age and the destruction and preservation.The paper at last further analyses the genesis of the deposit,establishing the prospecting model and prospecting indicators of the deposit.The conclusion demonstrates that Chuquicamata copper deposit,located in the central Andean orogenic belt,occurs in the Chuquicamata intrusive rocks and is mainly controlled by the Western fracture.The alteration zonation of the deposit is distributed in irregular shape and mineralization is closely related to the quartz-sericitization.The deposit has developed oxidation zone,and contains atacamite and malachite,which is similar with Tuwu porphyry copper deposit in China.The deposit was formed in the Late Eocene-Early Oligocene.The diagenetic and metallogenic materials are derived from the mantle,and the ore-bearing porphyry has a high oxygen fugacity,which is similar with Yulong and Qulong porphyry copper deposits in China.The formation of the deposit had experienced a number of superimposed mineralization.Metallogenic dynamic studies indicate that the formation of the deposit is related to quick oblique subduction movement between the South American plate and the Farallon plate.The geological characteristics and ore-controlling factors of Chuquicamata copper deposit summarized in this paper will offer valuable references for the exploration of porphyry copper deposit in China.

Geochemical Characteristics of Elements and Their Significance in the Ore Prospecting of the Hadamengou Gold Deposit,Inner Mongolia

Wan Wei, Wang Mingqi, Fan Huihu, Zuo Libo

2015, 34(5): 142-146.

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This article presents the geochemical analysis of the multielements for the wall rocks and ores from the 2nd and 13 rd gold veins of Hadamengou gold deposit.The studies show that the best index elements related with gold mineralization are Au,Te,Ag,Bi,Pb,Se,Mo,Cu,As and Sb,and that mineralization zoning exists in the area.The analysis of rare earth elements indicates that quartz veins containing the ore have no obvious Eu anomaly and quartz veins of surface have relatively obvious Eu anomaly.The rare earth elements of the ore show a increased trend to some extends from shallow to deep areas.These characteristics can provide a prospecting indicator for seeking Hadamenggou gold deposit in this area.

Characteristic and Cause Analysis in the Runoff-Drainage Area of Niangziguan Spring

Huo Jianguang, Zhao Chunhong, Liang Yongping, Wang Taoliang, Tang Chunlei, Wang Weitai, Shen Haoyong

2015, 34(5): 147-152.

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The runoff-drainage area of Niangziguan spring is mainly distributed in Yangquan City,Shanxi Province.Karst water of the spring is an important water supply for the city.The results of the assessment of the water quality variety through runoff-drainage area show that the karst water is seriously contaminated with the main pollutants of SO^2-₄,TDS and total hardness.The content of SO^2-₄in the karst has indicative significance for pollution source discrimination of total hardness and TDS.Applications of sulfur isotope(³⁴S)calculations show that mining is an important cause of water pollution of the karst water.The comparison of the present water quality with the water quality of 2003 demonstrates that the surface water and karst water from coal sulfur increases in the proportion of SO^2-₄,and this increase rate is maximum especially in karst water of the drainage area.

Conceptual Model of Redox Zonation in High Arsenic Groundwater System Under the Effect of Microorganisms

Zhang Junwen, Ma Teng, Feng Liang, Yan Yani

2015, 34(5): 153-159.

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Microbial activities have important effects on chemical composition and redox condition of groundwater,and also migration and transformation of arsenic.Researches on redox zonation in high arsenic groundwater system can help people to further understand the migration and transformation of arsenic in groundwater under the effect of microorganisms,and provide the theoretical basis for in-situ remediation of high arsenic groundwater.By reviewing the results of previous studies,this paper elucidates the adsorption,release and readsorption of arsenic in different biogeochemical stages,and depicts the conceptual model of redox zonation in high arsenic groundwater system.Along the groundwater flow paths,the electron acceptors are consumed sequentially in the order as dissolved oxygen>nitrate>Fe(III)>sulfate>CO₂.In dissolved oxygen and nitrate reduction stage,groundwater is in partial oxidation environment,and the arsenic will not be released into the groundwater as the Fe(III) reduction is inhibited.In Fe(III) reduction stage,groundwater is in reduction environment and the reductive dissolution of Fe(III) is the main process,so the arsenic will be released into the groundwater.When SO^2-₄reduction starts,groundwater is in strong reducing environment,and the sulfide that generated by combination of HS^- and Fe²⁺will adsorb or coprecipitate the arsenic,thus decreasing arsenic concentration in the groundwater.

Effects of Sediment Lithology and Groundwater Hydrochemical Characteristics on Fluorine Transport at Water-Soil Interface

Zhu Yapeng, Su Chunli, Liang Chuan, Xiang Hongyan

2015, 34(5): 160-165.

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Fluorine transport at water-soil interface affects formation of high fluoride groundwater.High fluoride groundwater occurring in Datong Basin is a serious problem,which is typical in China.In this paper,efforts were made to analyse the distributional characteristics of fluorine content and fluorine forms in the sediments of different lithologies,and to investigate the influence of pH,Ca₂₊,HCO^-₃ and H₂PO^-₄ on fluorine transport at water-soil interface using static experiments.The results show that contents of different fluorine forms in sediments descended in the following sequence:residual F ≥Fe/Mn oxide-F>water soluble F>organic F>exchangeable F.The order of fluorine contents in the aforementioned forms in different lithologies is:clay>silty clay>silt,in which clay minerals and calcite are main fixed fluorine minerals in sediments.In addition,the solution pH value and the concentrations of Ca²⁺,HCO^-₃ and H₂PO^-₄ are closely related to adsorption-desorption and dissolution-precipitation equilibrium of fluorine on the surface of sediments.The adsorption capacity of sediments on fluorine decreases with increasing pH and HCO-3concentration,but increases with the concentration of Ca²⁺ and H₂PO^-₄.

Risk Evaluation of Water Inrush in Karst Tunnel Based on Karst Evolution Model

Wu Yazun, Wan Junwei, Lin Yun, Cai Erbei

2015, 34(5): 166-171,179.

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The occurrence of water burst and water inrush in karst tunnel mainly depends on the development degree of karst cave and the structure type of karst system,which is closely related to the evolution of karst system.The evolution of karst system begin with the dissolution widening of cracks in rock mass by aggressive water.This study introduces the establishment of the karst evolution simulation model coupled with seepage model and dissolution widening model based on the regional hydrogeological conditions.The evolution simulation model is used to reconstruct the changes of water-bearing medium during the evolution process of Jigongling karst system.The result shows that,with the karst system's evolution,the fissures are widened progressively by dissolution with obvious differential dissolution and the heterogeneity of karst aquifer becomes more and more obvious.However,karst development extent and heterogeneity level become milder with the increase of depth.The average widening rate of fissures in the shallow system is almost 1500 times higher than that in the deep system.At the portal elevation of Jigongling tunnel,the karst development extent is mild,with the smaller dissolution widening fractures.The tunnel surrounding rocks are still a fractured rock mass with the permeability coefficient 0.51 m/d.The water inflow of 127.9m³/d when water burst accident happened is considered to be quite a small amount to exert effects on the tunnel construction.

Application of Seismic Sedimentology Technology in Reservoir Prediction of Wenchang A Oilfield

Li Da, Tao Qianqian, Sui Bo, Ma Guangke

2015, 34(5): 172-179.

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The point bar of coastal offshore environment and the deposition under offshore sheet sand are developed in ZJ1-2L oil group reservoir of Wenchang A Oilfield.The development of this oilfield is seriously constrained by its few wells,few typical seismic facies indexes,the gradual westward thinning of the reservoir until the thickness is smaller than the seismic data resolution and the difficult determination of the sandbody boundary.As the conventional reservoir prediction techniques cannot solve such problems,the paper adopts seismic sedimentology techniques to characterize the sandbody border.The time deposit reference plane is determined by the frequency division interpretation technology.According to the Wheeler transformation,a series of stratigraphic sections based on sequence stratigraphic isochronous trellis are established.The plane distributions of the sandbodies in different periods are presented by the interpretation of strata slices and domain play observation.The combination of frequency division inversion technique is applied based on above techniques and successfully achieves the fine description of reservoir distribution.The development and implementation results show the research results have a good coincidence in drilling data.

Identification and Description Technique for Ultra-Deep,Thin Reservoir,Narrow Channel Sand,Tahe Oilfield

Liang Honggang, Xian Wei, Li Wenping

2015, 34(5): 180-183.

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Channel sand body for 4th member of Triassic Akekule Formation in Tahe Oilfield is characterized by deep burial(>4 000m),thin sandstone(<10m),and quick lateral changes,which make it difficult to identify the characteristics of the seismic.Based on a small layer of contrast,under the constraints of sedimentary microfacies,this study integrated multi-attribute preferred application,time slicing,frequency mixing,3D visualization techniques to describe sand body distribution characteristics,and has established a set of reservoir identification and description technology for super-deep,thin sand,narrow channel sand bodies for 4th member of Triassic Akekule Formation in Tahe Oilfield.

Fracture Identification and the Response Characteristics of Fracture in the Third Drilling Hole of WFSD Project

Deng Chengxiang, Pan Heping, Fang Sinan

2015, 34(5): 184-189,198.

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The borehole of WFSD-3,located in the town of Jiulong in Mianzhu city of Sichuan Province,has comprehensive data and a variety of fracture.Based on imaging logging,studies on the conventional logging methods of the identification of fractures through the WFSD-3hole logging data.This paper sums up the response characteristics of fractures in imaging logging.Then it analyzes response characteristics of fractures of the conventional logging on the same depth.According to the sensitivity level of the various parameters for fractures identification,choose the more sensitive parameters for the further research of automatic identification.In the final analyzes the effect of this method.The results show that,these parameters like AC,DEN,CNL,R_MSL,R_p,m and F_RP have obvious response in fracture,especially AC and DEN are sensitive in low angle fracture.The discriminant function's recognition accuracy is 86.67%,which is constituted by these parameters,yielding relatively satisfactory application results.

Numerical Simulation on the Drilling Fluid Flowing in Gas Hydrate-Bearing Sediment at the Laboratory Scale

Zhou Xin, Ning Fulong, Sun Jiaxin, Zheng Mingming, Peng Li, Zhang Ling

2015, 34(5): 190-198.

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The invasion of drilling fluid into sediments around borehole will influence their physical properties,for example,strength and pore pressure.In the gas hydrate-bearing sediments(GHBS),the invasion process may couple with the dissociation and reformation of gas hydrates around the borehole,and then affect wellbore stability and log interpretation in GHBS.Thus,the investigation on the invasion dynamics of drilling fluid into GHBS is important for drilling and logging.Here,we used a numerical simulation method to analyze the dynamic behaviors of drilling mud invasion and flowing in GHBS at the laboratory scale according to field data and an experimental simulation system.The results show that the hydrate layer is obviously influenced by the mud invasion,and the density,temperature and salt content of the drilling mud all have great effects on the process of the invasion,especially the density which controls the heat and salt transfer efficiency to some content.Also,it is found that hydrate might decompose in the process of the fluid migration because of reducing the dissolved methane in the pore water and destroying the dynamic balance between natural gas hydrate,water and dissolved gas although the phase equilibrium state of gas hydrate was not broken.

Prediction of Karst Cave Conduit Using Lineament Density Method in Zhongxiepo Area,Lungu Oilfield

He Hu, Cai Zhongxian

2015, 34(5): 199-205.

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Lineament density,a kind of parameter reflecting the intensity of linear structur,is used to analyze the occurrence in mineral products and energy,the tectonic conditions of engineering geology and seismogeology initially.It is then used to predict the conduit path connecting the swallow holes and karst springs.Because of the subjectivity and uncertainty in predicting cave conduit using seismic attributes,this paper takes Ordovician karst cave conduit in Zhongxiepo area,Lungu Oilfield as the research object and,proposes a lineament density method based on fracture information calculated by ant-tracking and constrained by anisotropy of fracture and dipping-azimuth of bedding plane.The cave conduit prediction can be more accurate and effective by linearment density correction of the prediction by seismic attribute,and eventually will guide the exploration and development of carbonate reservoirs.

Dimension Reduction Method Combining Multi-Features for Hyperspectral Mineral Mapping

Su Yubin, Zhan Yunjun, Huang Jiejun, Ye Fawang, Zhang Chuan

2015, 34(5): 206-211.

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Hyperspectral remote sensing image is important in image spatial information and spectral information.However,the traditional dimension reduction method based on optimal band selection only considers the feature space information based on gray statistical characteristics,but ignores the image spatial information,thus causing a large amount of calculation.This paper,combined with the feature space information and image space information of hyperspectral remote sensing,proposes a new dimension reduction method combining multi-features of hyperspectral images and applies the method in mineral mapping.In this method,band correlation is first analyzed statistically and divided into different feature subspace.Then,fractal dimension of each band is computed and the band with the smallest fractal dimension is chosen as a candidate band in each subspace.Finally,calculation is made of the correlation coefficient between the spectrum of ground objects to be identified in the candidate bands so as to select quickly the optimal band combination.The result shows that,the image of the optimal band combination selected with this method is clear and shows an obvious correlation between different altered minerals.Besides,the mineral alteration information extracted by the method of mature spectral angle mapping(SAM)is roughly the same as the information extracted according to the feature selection.The above results indicates that the dimension reduction method combined with the image space and feature space can help to choose the ideal band combination.This reduces the dimension of hyperspectral image data and has a good effect of information extraction.

Application of CSAMT and Seismic Method to the Exploration of Geothermal Resource in Southern Hubao Basin,Inner Mongolia

Liu Ming, Yang Jin, Kang Junjian, Cao Wengeng, Yu Juan

2015, 34(5): 212-218.

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Abundant geothermal resources are stored in the Huhhot-Baotou Basin of Inner Mongolia Autonomous Region,which are mainly developed in the northern part of the basin.In order to find out the geothermal geological conditions in the southern part of the basin,the CSAMT method combined with 2D seismic method were used to conduct the geothermal resource exploration.Based on the measured data inversion,in combination with geological data and the full use of technical characteristics of different geophysical prospecting methods as well as the analysis and comparison of information concerning electrical property,stratum,fracture and hydrogeology of electrical structure and seismic site,the integrated interpretation is achieved with comprehensive research results.The distribution,geological structure and other geothermal geological conditions of the deep-seat faults in the exploration area were preliminarily ascertained.The study results provide the basis in geophysical prospecting and geological survey for comprehensive assessment and prospect forecast of geothermal resources in the basin.

Discussion on the Hazard Distance of Landslide-Debris Flow Triggered By Wenchuan Earthquake

Li Lunji, Han Jinliang

2015, 34(5): 219-224.

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To clarify the movement characteristics and predict the distance of landslide triggered by Wenchuan earthquake,this paper,using remote sensing image interpretation and field investigation data,discusses the correlation between the L and H to give the empirical formula and determines the key influence factors of earthquake landslides.The analysis of the difference between different types of landslides shows that:If H is known,total displacement can be preliminarily forecast by using the empirical formula L=aH+b or L=aH^b.It is applicable to treat 0.45 as the standard to measure high-speed and long runout avalanches in Wenchuan.The volume and the rupture area of the source region was positively correlated with the L,while H/L was negatively correlated with them.As earthquake landslide with ridgeline parallel to the rupture zone and perpendicular to the wave propagation direction is easy to occur,collapse-type landslide is much easier with the height range of 10 to 100m,with high-speed and long runout avalanches greater than 200 m.In the source region,the slope is generally distributed between 25ånd 51°.The slope of sliding bed changes between 0ånd 58°,while the slope of sliding bed of the high-speed and long runout avalanches is distribute in the range of 8°to 20°.The differences of the maximum movement distance is the result of the combined effects,such as distance effect,energy transfer and the baffle effect,rolling lubrication and air cushion effect,volume and rupture area effect,particle size distribution and particle flow effect,geological factors,the topography factor,etc.

LST:A New Inorganic Heavy Liquid Used in Conodont Separation

Yuan Jinling, Jiang Haishui, Wang Dacheng

2015, 34(5): 225-230.

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A new type of inorganic heavy liquid,LST(solution of lithium heteropolytungstates in water),used in microfossils or mineral grains separation,is introduced in this paper,for it has the advantages of non-toxic,lower viscosity,high density,high resistance to decomposition and high recycle rate.Based on the rich experiences in conodont separation,this paper describes in detail the procedure of the preparation,using and recycling of the LST heavy liquid.For the most efficient separation,a 2.80-2.81g/mL density of heavy liquid is recommended for limestone samples,while a 2.82-2.83g/mL density of heavy liquid is recommended for dolomite samples.Compared with the traditional heavy liquids,e.g.bromoform,tetrabromoethane,diiodomethane,thoulet solution and sodium polytungstate,LST heavy liquid has distinct superiority.We strongly suggest that the traditional organic and inorganic heavy liquids should be replaced by LST heavy liquid in separating microfossils and minerals.

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2015 Vol. 34, No. 5