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    20 September 2016, Volume 22 Issue 3
    A Discussion on Ore-forming Fluid Evolution and Genesis of Makeng Fe-Mo-Pb-Zn Polymetallic Deposit, Fujian Province
    LI Lin, NI Pei, YANG Yulong, XU Yingfeng, ZHU Renzhi, SUN Xuejuan
    2016, 22(3):  401. 
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    Makeng iron deposit is a large scale Fe-Mo-Pb-Zn polymentallic deposit in Fujian province hosted in the external contact
    zone of Juzhou-Dayang granites between the Jingshe Formation-Qixia Formation marbles and the Lindi Formation quartz sandstones.
    Mineralization stages can be classified into four stages: (1) anhydrous skarn stage (andradite-diopside); (2) hydrous skarn-magnetite
    (epdiote-chlorite-actinolite-hedenbergite);(3)sulfidesstage(quartz-calcite-fluorite-sphalerite-galena);(4)carbonatesstage(quartz-calcite).
    Petrographic and microthermometric studies of fluid inclusions in hedenbergite, fluorite, quartz and calcite of different mineralization
    stages show that the fluid inclusions related to magnetite mineralization are dominated by daughter mineral-bearing fluid inclusions,
    liquid-rich aqueous fluid inclusions, and minor vapor-rich fluid inclusions; fluid inclusions in sulfide mineralization stage mainlyinclude liquid-rich aqueous fluid inclusions. Ore fluid in iron oxide stage evidence for boiling at the temperature range of 448 to
    596℃, with salinities of 26.5 to 48.4 wt % NaCl equiv. for one end member fluid and 2.4 to 6.9 wt % NaCl equiv. for the other end
    member fluid. Whereas ore-forming fluid in sulfide stage exhibits a mixing trend, with the temperature and salinity of 182 to 343℃ and
    1.9 to 20.1 wt % NaCl equiv., respectively. Based on the fluid-inclusion data, early-stage magnetite mineralization fluids were
    originated mainly from magmatic water, and late-stage sulfide mineralization fluids were derived from mixtures of magmatic water and
    meteoric water. Because Fe mineralization was formed in the hydrous skarn stage and Pb-Zn mineralization was formed in the sulfide
    stage, the early-stage magnetite deposition may have resulted from fluid boiling and the late-stage sulfide deposition may have
    contributed to fluid mixing between magmatic water and meteoric water. Overall, the Makeng deposit is interpreted as a skarn type
    Fe-Mo-Pb-Zn polymentallic deposit related to intermediate-acid pluton based on skarn mineralogy and fluid inclusion characteristics.

    Study on Fluid Inclusions of the Datuanshan Copper (Molybdenum) Deposit at the Shizishan Orefield, Tongling City
    YANG Xiaonan, XU Zhaowen, WANG Yunjian
    2016, 22(3):  413.  DOI: 10.16108/j.issn1006-7493.20151
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    The Datuanshan copper (molybdenum) deposit is a typical magmatic-hydrothermal superimposing copper (molybdenum)
    deposit at the Shizishan orefield in Tongling, Anhui Province. This deposit is intimately associated with the Early Cretaceous
    Datuanshan quartz monzodiorite. Based on thorough petrographic observations of the ore-bearing quartz at the sulfide mineralization
    stage, we have identified plenty of primary fluid inclusion assemblages that are well preserved. Three types of primary fluid inclusions
    are described as vapor (Type I), aqueous (TypeⅡ), and daughter-mineral bearing multiphase inclusions (Type III). Statistical analysis of
    all the measured filling temperatures of the fluid inclusions shows two significant peaks at 375~405℃ and 285~315℃. The statistic peak
    for salinities appears in the range from 5.0 wt.% to 10.0 wt.% NaCl eq. Raman analyses reveal that water vapor is the dominant
    component in the gaseous phase, occasionally with small amount of CO2 and CH4. Hydrogen and oxygen isotopic compositions are
    characterized by magmatic water. These results suggest that the ore-forming fluids at the Datuanshan deposit were mainly derived from
    magmatic water. The fluids experienced multi-episodes of boiling, and were trapped from heterogenize fluid systems. Combining with
    results from previous relevant studies in literature, we conclude that the magmatic-hydrothermal fluids at the Shizishan orefield share
    common chemical properties, and experience similar physical chemical conditions. The multi-episode fluid boiling processes have
    probably played a key role in metal re-distribution, transport,and precipitation.

    Ore Geologly and Molybdenite Re-Os Dating of the Wulaxi Tungsten Deposit in Western Sichuan
    LI Tongzhu, ZHOU Qing*, ZHANG Huihua, DAI Yanpei, MA Guotao, MA Dong, SHEN Zhanw
    2016, 22(3):  423. 
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    The Wulaxi tungsten deposit is located in the southeastern Songpan-Ganzi orogenic belt. Based on considerable geological
    surveys and research, we suggest that this deposit belongs to skarn type tungsten deposit with a medium scale prospect. In this contribu?
    tion, Re-Os dating has been determined for the molybdenites from the Wulaxi tungsten deposit, which occurred as quartz veins and were
    spatially related to the scheelites. The analytical results yield model ages ranging from 161.5±2.2 to 165.3±2.2 Ma with a weighted mean
    age of 163.7±1.9 Ma (n=6, MSWD=0.42, 95% conf.), and a good isochron age of 161.0±3.7 Ma (n=6, MSWD=0.87, 2σ). The Re-Os geo?
    chronological signals show that the W-Mo mineralization occurred in the late stage of Middle Jurassic, slightly post-dated the formation
    of ore-bearing granite, indicating that it might be a product of the Yanshanion tectonic-magmatic-hydrothermal event in the region. The
    ore-forming source was possibly derived from the Proterozoic Liwu Group complex. In addition, there is favorable potential for ore pros?
    pecting at greater depths.

    LA-ICP-MS Zircon U-Pb Geochronology, Elemental and Sr-Nd-Hf Isotopic Geochemistry of the Xinfengjie Granitic Intrusion in Central Jiangxi Province, SE China, and Its Petrogenesis
    ZHU Shuqi, JIANG Yaohui*, WANG Guochang, NI Chunyu, QING Long
    2016, 22(3):  431. 
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    In this study, we present detailed LA-ICP-MS zircon U-Pb chronology, major and trace elements, and Sr-Nd-Hf isotopic
    data for the Xinfengjie pluton in central Jiangxi province, and discuss its petrogenesis and tectonic implications. Our results show
    that the Xinfengjie granites are composed of two-mica granites and biotite granites, both of which were formed in late Jurassic (ca.
    148 Ma). The two-mica granites have SiO2 contents of 75.71~78.36%. They are weakly peraluminous to strongly peraluminous rocks,
    and belong to high-K calc-alkaline series. Their Mg# vary from 0.26 to 0.34, and they have low Ga/Al ratios (mostly < 2.6×10-4) and low
    Zr+Nb+Ce+Y contents (<350×10-6). They have whole-rack εNd(t) of -10~-8.2, and zircon in-situ εHf(t) of -15.7~-9.4. The biotite
    granites have SiO2 contents of 71.25~74.41% . They are metaluminous to weakly peraluminous rocks, and also belong to high-Kcalc-alkaline series. Their Mg# vary from 0.32 to 0.37, and they also have low Ga/Al ratios (mostly < 2.6×10-4) and low Zr+Nb+Ce+Y
    contents (<350×10-6). They have initial 87Sr/86Sr ratios of 0.7136~0.7153, εNd(t) of -10.0~-8.9, and zircon in-situ εHf(t ) of -16.5~-10.9.
    Through our comprehensive research, we consider that the two-mica granites show characteristics of S-type granites, and were formed at
    lower temperature by partial melting of meta-pelite in the lower crust, while the biotite granites exhibit I-type affinity, and were formed
    at higher temperature by partial melting of felsic rocks in the lower crust. This pluton emplaced in a continental-arc tectonic regime
    which was induced by the subduction of the paleo-pacific plate.

    Petrogenesis of the Yangxin Complex in Southeast Hubei Province:Constraints from LA-ICP-MS U-Pb Ages and Hf Isotopes of Zircon
    DING Lixue, HUANG Guicheng, XIA Jinlong
    2016, 22(3):  443. 
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    The Yangxin pluton is the largest intrusion in southeast Hubei Province, and is also the section in which mineral resources
    are the most concentrated. The complex is mainly composed of quartz diorites and small-scale biotite quartz diorites. This paper
    presents high-precision zircon U-Pb ages and Hf isotopes of the Yangxin intrusion. The result indicates that its emplacement took place
    around 143~139 Ma, and the quartz diorites were emplaced earlier than the biotite quartz diorites. Both of them were products of
    magmatic activities in the peak period of this area. The calculation results of Ti-in-zircon thermometer show that the quartz diorites
    were mainly formed in the temperature ranging from 787℃ to 876℃ , and the biotite quartz diorites were mainly formed in the
    temperature ranging from 686℃ to 805℃. The zircon Hf isotopic data show that εHf(t) values of the quartz diorites range from-11.42
    to-3.31, and εHf(t) values of the biotite quartz diorites are obviously lower and have a wider distribution (from -21.75 to -1.44). Combined
    with geochemical, Sr and Nd isotopic and mineral chemical characteristics, both quartz diorites and biotite quartz diorites were likely
    derived from enriched lithospheric mantle, as well as fractional crystallization and assimilation followed. Moreover, quartz dioritescrystallized earlier in higher temperature, while the biotite quartz diorites crystallized later in the lower temperature with addition of
    more crustal materials.

    Geological Characteristics and Genesis of the Lingshan Complex in Jiangxi Province
    WU Xuling,FAN Xiujun,GONG Chayun,XIAO Xing,HUA Xin,FANG Junhua
    2016, 22(3):  459. 
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    The Lingshan granitic pluton is located at Huaiyu depression in the southern belt of Qinhang junction, Jiangxi Province. It
    occurs as a multistage batholith in a circle shape. The whole-rock SiO2 contents of the Linshan granite range from 69.16 wt.% to 76.45
    wt.%, and the contents of K2O+Na2O range from 6.41 wt.% to 9.44 wt.%. They are acid to ultra-acid, and belong to the high K
    calc-alkaline to shoshonite series. The Rittmann Index is in an average of 2.42. They are enriched in Rb, Th, U, Nd, Hf, Zr, Y, Nb and
    Ta, but depleted in Ba, Sr, P and Ti. The total REE contents are in the range of 79.08×10-6~629.88×10-6. The ratios of La/Yb are in
    the range of 4.66~20.86, while the δEu values range from 0.11 to 0.45, with strong negative Eu anomalies. The authors analyzed the
    intrusive contact relationship between the different units of the complex after“Mineral resources geological survey for Lingshan area in
    Jiangxi province”. The data show that the complex pluton was controlled by the northeast to northwest fracture intersection. The locally
    intracontinental extension environment induced the A-type granitic melts ascending and emplacement from southwest to northeast as
    asymmetric inflatable balloons. Their rock- and ore-forming ages are around early Cretaceous. Geyuan-Zhangcun is a potential area to
    find ore deposits similar to those associated with the Lingshan granitic pluton.

    Matrix Effect on Barium Oxide and Hydroxide Formation During ICP-MS Measurement and Its Implication for Eu Correction
    ZHU Bi, LIU Qian, YANG Tao
    2016, 22(3):  467. 
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    Precise and accurate determination of Europium concentration in geological sample using Inductively Coupled Plasma Mass
    Spectrometry (ICP-MS) is hindered by severe spectroscopic overlap of BaO + and BaOH + ions. Correction for Eu concentration
    mathematically based on precise determination of (BaO+ +BaOH+)/Ba ratios is an applicable method. However, whether the ratios vary
    with varying matrix and Ba concentrations remain uncertain. In the current study, we investigated variations in (BaO+ +BaOH+ )/Ba
    ratios in solutions by changing matrix and Ba contents in analyzed solutions. The results show that during the course of measurement,
    when keeping constant the matrix in solutions, the ratios are almost invariant at different Ba concentrations. In contrast, the matrix ofsolution has a major impact on the (BaO+ +BaOH+)/Ba ratios. Corrected Eu concentrations using the (BaO+ +BaOH+)/Ba ratios
    obtained are comparable to results obtained using high resolution mode(R=10000), with replicate analysis showing good
    reproducibility. The results show that using matrix-matching solution is essential for mathematical correction of Eu concentration.

    Detrital Zircon Geochronology and Directional Structures of Cambrian Sediments in Jiangshan of Zhejiang Provence and Their Palaeogeographic Significance
    HUANG Renbo, LIU Jiarun*, YANG Zhenyu, JIAO Wenjun, LI Yongxiang
    2016, 22(3):  474. 
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    In this study, the age spectra of detrital zircons and sedimentary directional structures are used to investigate the
    paleogeographic features, especially the paleogeography in east Cathaysian Block. The dating results of detrital zircons from clastic
    interlayers of the Yangliugang Formation in northern Jiangshan of Zhejiang Province, which lies on the southeastern margin of the
    Yangtze Block, show that the ages range from 515 Ma to 3340 Ma, with a major peak at 828 Ma and secondary peaks at 727 Ma and
    916 Ma in the detrital age spectrum. Moreover, the result of spectrum correlation suggests that northern Jiangshan might be affinity to
    northwestern Fujian and eastern central Jiangxi in the Cathaysian Block as well as northeastern Jiangxi and southern Anhui in the
    Yangtze Block, however, irrelative with southwestern Fujian and southern Jiangxi in the Cathaysian Block. On the other hand, the
    features of sedimentary directional structures, which include syndepositional slump folds in the Yangliugang Formation and the
    overlying Huayansi Formation and cross beddings in the underlying Dachenling Formation, indicate that the sedimentary basement
    inclined toward the northwest and the sediment transport direction was from the southeast to the northwest during depositional periods
    of these formations. And then, it can be deduced that the provenance of zircon-bearing clastics in the Yangliugang Formation might belocated in the nowadays central part of Zhejiang Province of eastern Cathaysian Block, in which there are outcrops of metamorphic
    rocks with known age corresponding to 42% detrital zircons in this study. Toward the northwest, the detrital source might have supplied
    clastics eroded from older strata or redeposited materials originated from older strata. These strata mainly include the Chencai Group
    and the equivalent to Heshangzhen Group and Shuangxiwu Group, which contain intrusive and volcanic rocks.

    Olenoides Meek, 1877 from the “Tsinghsutung Formation”at Balang, Jianhe County, Guizhou Province
    WANG Mingkun, ZHAO Yuanlong*, LUO Xiuchun, CHEN Wanyi
    2016, 22(3):  486. 
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    The Jianhe Biota discovered in the“Tsinghsutung Formation”(Cambrian Stage 4) at Songshan (Jiugaoshan) Section near
    Balang Village, Jianhe County, Guizhou Province consists of soft-bodied fossils with abundant trilobites. Olenoides Meek, 1877
    (Dorypygidae, Trilobita), ranging from Cambrian Duyunian (Stage 4) to the late Cambrian Guzhangian (Stage 7), is an important fossil
    for global stratigraphic correlation. This taxon from the“Tsinghsutung Formation”includes 2 species: Olenoides contrictus (Chien,
    1961) andO. cf. hubeiensis (Sun, 1984) which are the primitive morphotypes of O. paraptus and O. hubeiensis that occurred in the
    overlying Kaili Formation. The Olenoides from the“Tsinghsutung Formation”(lower Duyunian, Qiandongian, global Cambrian Series 2)
    is known to be the lowermost occurrence for this genus. The discovery of Olenoides in the“Tsingsutung Formation”not only sheds new
    light on the early morphology, evolution, and distribution of this group, but also provides new constraint for the biostratigraphic study of
    Cambrian Stage 4 (Duyunian).

    Restudy on The Arthricocephalus chauveaui Bergeron 1899 from the Cambrian Qiandongian in Northwestern Hunan
    LEI Qianping
    2016, 22(3):  494. 
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    Recently, the concept and synonyms of the genus Arthricocephalus have been redefined, most species of the traditional
    “Arthricocephalus”should be assigned into Oryctocarella, and the Arthricocephalites is the junior synonym of Arthricocephalus. Based
    on several specimens of different ontogenetic development stages collected from Zila Village, Huayuan County of northwestern Hunan,
    this study shows that the different thoracic segments may be accounted for different development stages, but not the interspecific
    variations. Furthermore, several species have been reassigned into Arthricocephalus chauveaui Bergeron 1899, and the intraspecific
    vitiations within the genus have been discussed. The morphology and stratigraphical information of Arthricocephalus with other
    oryctocephlid trilobties have been compared and their evolutionary relationships have also been discussed in the current study.

    Study on the Origin and Evolution of Transpressional Structural Belt and Its Control on Oil and Gas Accumulation in the South of Liaozhong Sub-sag, Bohai Sea Area
    LI Wei, CHEN Xingpeng, WU Zhiping, ZHANG Jing, REN Jian, LIU Chao, LI Chunrui
    2016, 22(3):  502. 
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    Based on the detailed interpretation of three-dimensional seismic data, horizontal coherent slices and seismic lines of
    different directions were used to analyze the development features of transpressional structural belt in the south of Liaozhong sub-sag.
    Combined with the stratum development and stress field, the genesis and evolution of transpressional structural belt was studied and its
    control of hydrocarbon accumulation was discussed. The result shows that the origin and evolution of transpressional structural belt are
    controlled by the NNE trending Liaozhong 1 Fault and the Central Strike-slip Fault. These two faults mainly show both extensional and
    strike-slip features, and occur as a“S”-shaped left-stepped arrangement on the plane. Extensional subsidence during Early Paleogene
    and the compressive stress derived from strike-slip fault of Late Paleogene are the main controlling factors of the origin and evolution of
    transpressional structural belt in the Liaozhong sub-sag. Extensional subsidence of Ek-Es3 in the Paleogene in the south of Liaozhong
    sub-sag and tectonic transformation at the end of Es3 led to the formation of transpressional structural belt. At the end of Paleogene(Ed),
    Liaozhong 1 Fault and the Central Strike-slip Fault showed strong dextral strike-slip. During the dextral shear, the left-stepped
    arrangement and the“S”shape of central strike-slip fault generated regional compressional stress. After this, the tectonic compression of
    Dongying movement at the end of Paleogene and Bohai movement at the end of Neogene reshaped its pattern continuously.Transpressional structural belt showed a convexed top and a concaved bottom, and the strata of the Dongying Group and the Neogene
    System became bent to form upward arches. Transpressional structural belt is a favorable area for hydrocarbon accumulation and the
    Central Strike-slip fault as the main plugging fault is tightly closed and it is beneficial to lateral sealing at the stress-increasing part of the
    "S"-shaped bend, which is an advantageous factor for the formation of large-medium size oil and gas reservoirs.

    Distribution Characteristics and Geological Significance of Trace Elements of Mudstone of the Yacheng Formation, Well Y1, in Yanan Sag, Qiongdongnan Basin
    张春良,沈玉林*,秦勇,赵志刚,谢国梁,郑俊
    2016, 22(3):  512. 
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    In order to investigate the distribution of trace elements of mudstone and its geological significance in the Yacheng Formation
    in Yanan sag, the trace elements of 13 mudstone samples that were collected from Y1 well were analyzed by ICP-MS. The results show
    that (1) A majority of continental elements and a minority of thalassophile elements are enriched, indicating a transitional environment.
    The periodic development of coal accumulation is recorded the trace elements such as U, Ba, Th, Sr showing cyclic changes with depth
    marked by distinct cycle boundaries. These boundaries indicate the transgression surface and the exposed surface of unconformity; (2)
    The climate was warm and humid during the deposition period in the Yacheng Formation in the study region as indicated by Sr/Cu, V/(V+
    Ni) and Ni/Co ratios indicating poor oxygen condition during this period. In addition, high S content suggests the existence of theYacheng transgression events in the Oligocene when Qiongdongnan Basin was transformed from a faulted depression to a sag basin while
    the regional sea-level rose.

    Study on the Sequence Stratigrahy and Seismic Facies of the Abu Gabra Formation in Nugara Depression,Muglad Basin,Sudan
    WANG Xin,ZHU Xiaomin*,WU Dong,LI Zhi,XIAN Benzhong,LIU Aixiang,
    2016, 22(3):  519. 
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    Based on integrated analysis of seismic and well logging data, the AG Formation, a supersequence, in the Nugara Depression
    of Muglad Basin of Sudan can be subdivided into five 3rd order sequences named SQA~SQE from the bottom to the top. The
    characteristics of each sequence boundary are clearly shown in both seismic profiles and well logs. In the sequence stratigraphic
    framework, according to the internal reflection textures and external geometric configurations and in combination with characteristics of
    seismic amplitude, continuity and frequency, five seismic facies are identified in the AG Formation including parallel-subparallel sheet,
    wedge shaped, foreset, moundy and unorganized seismic facies. These seismic facies can help build the evolution model of sedimentary
    facies because these facies should be continuous and can be inherited. The normal delta, braided delta, fan delta, lacustrine system and
    alluvial fan can be recognized based on seismic data, well data as well as cores. The seismic-sedimentary facies evolution and its
    controlling factors are also analyzed in this paper.

    Subsidence History Analysis and Separation of Anomalous Subsidence During the Post-rift Stage in the Central and Northern
    BAI Yu, LIU Shaofeng*, LI Chao, MA Fangbin
    2016, 22(3):  530. 
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    In order to explore the relationship between the anomalous subsidence during the post-rift stage in the central and northern
    Bohai Bay Basin and the process of the western pacific plate subduction, we collected and compiled data from 27 wells and one seismic
    profile and a geological cross-section. We also simulated the strain rate of the crust during the syn-rift stage and the anomalous
    subsidence during the post-rift stage for each borehole by using the back-stripping technology and the strain rate inversion method. Thesubsidence events. The average tectonic subsidence rate is 4.6 m/Ma during the first episode (60~42 Ma), corresponding to Ek-Es4, is
    5.5~30.5 m/Ma during the second episode (42~36 Ma), corresponding to Es3-Es2, and is 14.7~54.7 m/Ma during the third episode
    (36~24.6 Ma), corresponding to Es1-Ed. There are obvious differences between the observed tectonic subsidence and the simulated
    subsidence during the post-rift stage in the study region, which indicate the anomalous subsidence. The anomalous subsidence in the
    northern region is about 100~200 m and is about 500~700 m in the central Bohai sea region, the anomalous subsidence during the
    post-rift stage increases towards the sea. The post-rift anomalous subsidence was probably caused by the subduction of the Pacific Plate,
    which induced a down-drag force due to the flow of the deep mantle material. Therefore, the anomalous subsidence in Bohai Bay Basin
    might be related to dynamic subsidence.

    Description of the Storage-Permeability Under the Control of Macrolithotypes Based on the Nuclear Magnetic Resonance
    LIU Yulong,TANG Dazhen,XU Hao, ZHAO Junlong,LI Bingyang
    2016, 22(3):  543. 
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    In order to explore the characteristics of storage-permeability and the heterogeneity within the coal macrolithotypes, the
    medium-high rank samples of different macrolithotypes in Hancheng mining area, were studied using the low field nuclear magnetic
    resonance technique, fine description and quantitative characterization of pore-fracture system and the difference in the effective
    porosity within different macrolithotypes in Hancheng mining area have been obtained. Based on the cumulative amplitude curves
    before and after centrifugation, the threshold T2C1 and T2C2, which can divide the pore-fracture system, was obtained, and the
    reconstruction of proe size distribution of different macrolithotypes was established. The experimental results show that different
    macrolithotypes of coal samples have significantly different T2 spectrum, which shows from the bright coal to the dull coal. The T2
    spectrum from the double macropore type is gradually transformed to the double micropore type, and both of T2C cutoff value and
    effective porosity show a gradually decreasing trend. The distribution of the pore-fracture system, which was obtained by the threshold
    of T2C1 and T2C2, show that, from the bright coal to the dull coal, the pore-fracture structure of the reservoir transformed from the seepage
    pore type to the comprehension type and the diffusion type.

    Influence of Biodegradation on Light Hydrocarbon Parameters in Crude Oil of Kuqa Formation from Dawanqi Oilfield
    YANG Lu, LI Meijun*, ZHANG Chunming
    2016, 22(3):  549. 
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    Oil samples from Dawanqi Oilfield in the Tarim Basin, NW China, that have been biodegraded to various degrees were
    analyzed to study the effect of biodegradation on light hydrocarbons. The results show that biodegradation led to preferential depletion
    of n-alkanes, followed by iso-alkanes and cycloalkanes, which results in variations in the corresponding C6 and C7 ternary diagram. With
    increasing biodegradation, the values of n-heptane and isoheptane decrease, ratios of toluene/n-heptane and benzene/n-hexane increase,
    and n-heptane/methylcyclohexane ratio decreases. In Dawanqi Oilfield, the crude oil with heptane values of 0~21 and isoheptane
    values of 0~2.6, is categorized as“Biodegraded”zone. The graph of toluene/n-heptane versus n-heptane/methylcyclohexane indicates
    that secondary alterations should be applied with caution in slightly biodegraded crude oil.

    The Application of Ant Colony Algorithm Based on the Theory of Development Fluid Potential in Predicting Preponderance Flow Path
    ZHAO Junwei, XU Huaimin*, JIANG Tongwen, WU Zhuo, XU Zhaohui
    2016, 22(3):  555. 
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    The formation of preponderance flow path will affect the result of water injection in a reservoir. How to recognize and predict
    it becomes the focus of this research. In this paper, a method has been proposed to predict dominant flow path using ant colony
    algorithm based on the theory of development fluid potential. It is believed that a development fluid potential includes gravitational
    potential energy, pressure energy, kinetic energy and interfacial energy. The difference in fluid distribution in a reservoir determines
    the differences of fluid potential in the reservoir. Ant colony algorithm is introduced into the reservoir development, and it is considered
    that the formation of both the ant migration path and the preponderance flow path in the reservoir have the characteristics of regularity,
    stochastic and optimality. The model of ant colony algorithm based on fluid potential field is proposed. The new methods have beenused in Donghe 1 oilfield, after establishing the fluid potential model in a reservoir, ant colony algorithm simulation is conducted in
    fluid potential profile crossing wells. In initial simulation stage, the distribution of high density pheromones is different among different
    rhythm layers controlled by development fluid potential distribution differences in inner layer, which means that the distributions of
    preponderance flow path are different in different layers. In later simulation stage, controlled by fluid potential distribution differences
    interlayer, high concentration pheromones are mainly distributed in the 2-2, 3-1 and 3-2 layers namely, the preponderance flow path is
    well developed in these layers. Dynamic data have been used to verify it and the results are in good agreement.

    Identification of Groundwater Contaminant Source Based on Adjoint-state Method
    CAO Tongtong, ZENG Xiankui*, WU Jichun1, LU Wenxi
    2016, 22(3):  563. 
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    The identification of contaminant source can not only provide a basis for developing groundwater management plan, but also
    be convenient to investigate for responsibility of relevant polluters. First, the sensitivity matrix is used to establish the mathematical
    relationship between monitoring data and characteristics of contaminant source. Then, adjoint-state method is applied to derive the
    identification model of contaminant source. Second, adjoint-state method is applied to four cases where single or multiple sources exist
    in two-dimensional homogeneous or heterogeneous media, the location and strength of contaminant sources can be identified according
    to the monitoring data. Finally, the availability and effectiveness of adjoint-state method should be validated by comparing the results
    from the adjoint-state method with the real characteristics of the contaminant source. The results show that the adjoint-state method has
    good applicability in indentifying contaminant source, which can be used to identify the position and strength of groundwater
    contaminant source, and can improve calculation efficiency.

    Verification of Effectiveness of Light Transmission Study on Fluid Phase Saturation Using Numerical Modeling Method: Cases of Water-gas Flow in Heterogeneous Porous Media
    MO Longting, QIAO Wenjing, ZHANG Yanhong, YE Shujun*, WU Jichun
    2016, 22(3):  572. 
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    Light Transmission Method has been extensively used in phase saturation measurements in porous media due to its
    non-destructive and non-invasive feature. However doubt about its effectiveness still exists due to the lack of local data validation.
    Given the fact that it is impossible to obtain local data experimentally, numerical simulation was then developed to verify its
    effectiveness, in the cases of water-gas flow in heterogeneous porous media. The results show that (1) simulation results agree with the
    light transmission results in terms of the gas distribution pattern and gas saturation range in the heterogeneous porous media; (2) six
    local saturation values of light transmission results in time-series graph show good consistency with the simulation results at each
    moments, meanwhile the analysis of 5316 local saturation data within 12 minutes shows the determination coefficient reaches 0.94
    between the simulation results and the light transmission results. The results validate the effectiveness of light transmission method at
    local points, with the difference being caused by the sandbox packing; (3) the total gas volume calculated by both simulation and the
    water displacement volume agree with the data by light transmission results. Through these three qualitative and quantitative analyses,this paper verifies the effectiveness of light transmission method in measuring liquid saturation.

    Numerical Simulation on the Size Effect of Compressive Strength and Deformation Parameters of Rock Materials Under Different Confining Pressures
    TANG Wei, ZHAO Xiaobao*, LEI Jiyuan, Yuan Bin, LIU Hanwen
    2016, 22(3):  580. 
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    The compressive strength and deformation parameters of rock materials are important indices of rock engineering. Because a
    rock is a typical heterogeneous material, its strength and deformation parameters vary with sample sizes. In this paper, the size effects
    of rock materials under different confining pressures were numerically studied using PFC2D code. The simulation results indicate that
    (1) rock strength, peak strain and compressive modulus decrease with increasing specimen sizes, whereas the change of specimen size
    has little effect on the failure mode of these rock specimens. (2) rock strength, peak strain and compressive modulus increase with the
    confining pressures. Among them, the rock strength and peak strain have linear relations with the confining pressures. In addition, the
    failure of rock specimens gradually changes from the splitting mode into shear failure mode with the increase in confining pressures.
    (3) the increments of rock strength and peak strain for different size specimens at the same confining pressure range are approximately
    the same. Meanwhile, these two parameters increase with confining pressures. Therefore, the size effect of the rock strength and peak
    strain at high confining pressure becomes weak. In addition, the increasing ratios of compressive modulus for the corresponding
    scenarios are similar, which causes the confining pressure to have little impact on the size effect of compressive modulus.