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    16 January 2013, Volume 27 Issue 1
    Engineering Geology and Environmental Geology
    Primary Halo Research of the Main Ore Zone in the Huachanggou Gold Deposit in Lüeyang, Shaanxi Province
    LIU Chong-hao,LIU Jia-jun,JIA Lei,WANG Wei-yu,WANG Li-xin,YU Kang-wei,CHEN Dong
    2013, 27(1):  1-12. 
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    On the basis of field geological work, the paper analyzes the microelements of the samples of the main ore zone, with the methods of geomathematic analysis and the calculation of the primary halo zoning. The result shows that the primary halo axial zoning sequence of ore body Au11 is Hg-Sb-Ni-As-Bi-Cu-Au-Co-Zn-W-Mo-Mn-Pb-Ag-Cd, and the primary halo axial zoning sequence of ore body Au8 is Cu-Co-W-Au-Ni-Sb-Mn-As-Pb-Bi-Hg-Mo-Ag-Zn-Cd. The ideal primary halo axial zoning sequence of the main ore zone is brought forward, which is Sb-As-Cu-Hg(front halo elements)→Au-Ag-Bi-Pb-W(nearore hole elements)→Ni-Co-Mn-Mo-Zn-Cd(rear halo elements).According to the characteristics of contrast halo zoning of the two ore bodies, the ideal zoning models of the primary superimposed halos are built. In ore body Au11, the front halo is coexistent with the rear halo in 1,150 m middle section, and the rear halo appears obviously in 1,110 m middle section. In ore body Au8, the front halo is coexistent with the rear halo in 1,150 m and 1,070 m middle sections; the near-ore halo is decreased in 1,110 m middle section with ore body thinning and the weakening of the front and the rear halos. According to the results mentioned above, ore body Au11 is extending to the deep part; the underlying part of ore body Au8 is not deep, but there is a new ore body in deep part.

    Isotope Geochemistry of the Wurinitu W-Mo Deposit in Sunid Zuoqi, Inner Mongolia, China
    YANG Zeng-hai,WANG Jian-ping,LIU Jia-jun,WANG Shou-guang,WANG Qing-yi
    2013, 27(1):  13-23. 
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    The Wurinitu W-Mo deposit,located in Sunid Zuoqi, Inner Mongolia, is a large scaled W-Mo deposit which is discovered in recent years.The W-Mo orebodies mainly occurred in Yanshanian granite rock body and the nearby contact zone,with the major type of veinlet mineralization.The measured δ34SV-CDT value of the Wurinitu orebody  (0.6‰ to 4.1‰)  varies in a very limited range and suggests that the formation of W-Mo ore-body is closely related to magmatism and the sulfur may be leached from the granite intrusion.Based on tectonic patterns of lead isotope and related parameters,the lead isotopic compositions of the Wurinitu orebody (208Pb/204Pb=38.115-38.353,207Pb/204Pb=15.528-15.591,206Pb/204Pb=18.375-18.528) indicate that the mineralization may be induced by the magmatism,and ore-forming material is characterized by the source of lower crust and show crustmantle mixing.δ13CPDB and δ18OSMOW of the hydrothermal calcite are from -8.63‰ to -6.41‰ and from -1.49‰ to 8.72‰, respectively.It shows that the hydrothermal calcite forms in two mineralization stages.The CO2 in the earlier stage is related to the magma;and the later hydrothermal ore fluids show the characteristics of mixture fluids of meteoric water with magmatic water as the meteoric water added.

    Studies on Ore-forming Fluid Characteristics and Mineralization Mechanisms of the Lawu Copper Polymetallic Deposit, Tibet
    LV Peng-rui, CHENG Wen-bin, WU Cheng-yun, PENG Yi-wei, PENG Tao-tao
    2013, 27(1):  24-36. 
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    The Lawu copper polymetallic deposit occurred at Xainza-Poindo Cu-Ag-Pb-Zn-Au mineralization sub-zone in Gangdese magmatic-tectonic metallogenic belt. The petrographic observation and microthermometry study were carried out on the fluid inclusions from garnet in anhydrous skarn stage (Ⅰ), quartz in early sulfide stage (Ⅲ) and calcite in late sulfide stage (Ⅳ). The petrographic observations present that various types of fluid inclusions occurred in hydrothermal minerals of different ore-forming stages, which include mainly vapor-liquid two-phase H2O inclusions, subordinately liquid H2O inclusions, with occasional vapor-liquid two-phase CH4 inclusions, as well as NaCl daughter mineral-bearing multiphase inclusions occurred in quartz. And the studying results show that their homogenization temperatures vary from 95 ℃ to 476 ℃, while their salinities are 1.57%-37.33% NaCl eqv and their densities range from 0.68 g/cm3 to 1.23 g/cm3, overall belonging to the ore-forming system of medium-high temperature, medium-low salinity and medium density; and the mineralization pressures, calculated on the basis of homogenization temperatures and salinities mentioned above, vary from 24.63 MPa to 133.61 MPa, while the ore-forming depths range from 2.46 km to 9.64 km, indicating that this mineral deposit formed in mesogene mineralization environment. The data of fluid inclusions in different ore-forming stages indicate that, the mineralization of this deposit is a process of the homogenization temperatures, salinities, ore-forming pressures and depths explicitly decreasing, and of the densities slightly increasing. H-O isotopic studies have shown that, the ore-forming fluids are dominated by the initial mixture of magmatic and meteoric water in the main ore-forming stage, but a great amount of precipitation is added in the following mineralization stages, thus the ore-forming fluids evolved into meteoric water in the later oreforming stage. The boiling events took place in stage Ⅲ, resulting the precipitations of ore-forming elements and forming the ore-bodies. Therefore, it is believed that the boiling is severed as the main mechanism for the metallic sedimentation of this mineral deposit.

    Thermoelectricity Characteristics of Pyrite from Xincheng Gold Deposit, Eastern Shandong
    JI Xing-zhong, YANG Li-qiang, WANG Zhong-liang
    2013, 27(1):  37-45. 
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    Xincheng gold deposit, located in the Jiaojia gold field of Eastern Shandong, is a super-large altered cataclastic rock type gold deposit. Pyrite is recognized as the most important gold-bearing mineral in this deposit. Combined with thermoelectricity characteristics of pyrite from different depths and exploration lines of Xincheng gold deposit, the spatial distribution regularities of thermoelectric conductive type of pyrite, the mine-ralization temperature and the denudation rate of ore body are discussed in this paper, and we proposed the prospective ore area in the deeper areas. Research shows, compared to N-type (less than 30%), the thermoelectric conductive type of pyrite of Xincheng gold deposit is mainly P-type (70.20%), whose thermoelectric coefficient is 180 to 320 μV·℃-1 and -180 to -80 μV·℃-1 respectively; the variation trend of thermoelectric conductive type is P→N from shallow to deep areas; mineralizing temperature centers on 180 to 340 ℃, which indicates that it is a mesothermal deposit; denudation rate of ore body is 49.98%. Combined with the field geological study and the data in this paper, three ore prospective areas are proposed: depth below -630 m from 149 to 157 and from 181 to 193 exploration lines, and depth below -730 m from 161 to 179 exploration lines.

    Geochemical Characteristics and Genesis of Large Devonian Barite Deposits in Zhenning County, Guizhou Province
    GAO Jun-bo,YANG Rui-dong,TAO Ping,WEI Huai-rui,LIU Kun,CHENG Wei
    2013, 27(1):  46-55. 
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    Shuicheng-Ziyun-Nandan deep fault is a well-known belt expanding across two provinces (Guizhou and Guangxi), along both sides distributing a series of diverse deposit types, and the large Devonian barite deposit is an important ore deposit in Zhenning County, Guizhou. The large barite deposit, located in the northwest margin of Shuicheng-Ziyun-Nandan deep fault was studied on the basis of the sedimentation characteristics, geochemistry and metallogenic background. The results revealed coexistence of a variety of hydrothermal water sedimentary structures characteristics such as laminar structures, barite-banded structure, brecciated structure, barite-fragmental structure, massive structure, and so on. Macroelement study indicated that the  deposit was formed probably by synsedimentation of SiO2 and ore-bearing sulfate fluid. Besides, geochemistry of the large barite deposits of the Devonian shows the enrichment of Sr, Zn and W, strongly suggesting that the barite deposits is hydrothermal sedimentation in origin. The diagrams of lgU-lgTh and Cr-Zr in the barite deposit also present the features of hydrothermal sedimentation. According to the REE distribution pattern, LREE were enriched and Eu was positive while Ce was negative, which also shows a hydrothermal feature. As a result, we believed that the large barite deposits located in Zhenning formed by hydrothermal exhalative mineralization.

    Geochemical Characteristics of Pluton in the Haoyaoerhudong Gold Deposit of Inner Mongolia and Its Ore-forming Significance
    WANG Yu-feng,WANG Jian-ping,WANG Huan,SUN Hu,JIANG Xiang-dong,
    2013, 27(1):  56-66. 
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    The Haoyaoerhudong gold deposit is located in the west of the Mesoproterozoic Bayan Obo rift on the west section of the northern margin of the North China Platform. A lot of granitoid plutons and dykes appear in the interior and outskirts of the diggings mainly including quartz monzodiorite, monzonitic granite and alkali feldspar granite whose enclaves are named as monzogabbro. By analyzing the characteristics of petrography and petrogeochemistry, combining with the intrusion era of the same type plutons in the same region, the Haoyaoer-hudong pluton was considered to be formed in the syn-collisional and post-collisional environment of North China Plate and Siberia Plate. Among them, the monzonitic granite formed in syn-collisional environment, and is possibly influenced by the heat of melting of the underthrust plate and mantle wedge in the process of subduction, of which the parental magma derived from partial melting of lower crust; the quartz monzodiorite formed in the uplift environment of post-collisional, resulting from the melt of the thickening lower crust; the alkali feldspar granite belongs to the series of A-type granites of the late orogenic era when the mantle basaltic magma underplated leading to the lower crust melting and being mixed. Combing with the mineralization ages, the characteristics of the mineralization fluid and organic geochemistry of host rocks, the invasion of pluton is considered to offer essential heat and part of ore-forming fluid sources.

    SHRIMP Geochronology and Hf Isotope of Zircons from Granitoids of the Weilasituo Deposit in Inner Mongolia
    WANG Xin-yu,HOU Qing-ye,WANG Jin,CHEN Yue-long,LIU Jin-bao,WANG Zhong,LI Da-peng
    2013, 27(1):  67-78. 
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    Weilasituo copper polymetallic deposit is located in the intersection of central Asia orogenic belt and Da Xinganling orogenic belt. The zircon SHRIMP U-Pb dating shows that granitoids ages are (298.0±2.5) Ma,(308.3±4.2) Ma,(313.9±3.4) Ma and (320.5±4.1) Ma,indicating that they formed in Late Carboniferous. Rock geochemistry characteristics shows that the granitoids are the product of magmatic arc activities. Except for the zircons of granodiorites samples with εHf(t) values from -4.1 to+4.08, the zircon εHf(t) values of the other samples are positive, ranging from +0.4 to +9.9. The peak of zircon Hf model age is consistent with the time of Paleo-Asian Ocean development, suggesting that the main source material of granitoids in mining area is the subducted oceanic curst of the Paleo-Asian Ocean and some Precambrian crust. Systematic study on granitoids in mining area may provide the basic information for exploring the evolution of Xinganling-Mongolian orogenic belt in the Late Paleozoic and new evidence for the genesis of copper polymetallic deposit.

    Zircon U-Pb Ages of Clastic Sediment from the Outfall of the Yellow River and Their Geological Significance
    ZHENG Ping,LI Da-peng,CHEN Yue-long,HOU Ke-jun,LIU Chang-zheng
    2013, 27(1):  79-90. 
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    Terrigenous clastic sedimentary rocks (sediments) are natural mixture of their provenance materials, preserving important information of different processes on their provenances, which can usually be used as key clues of processes of basin sedimentation, regional tectonic, crustal growth and evolution, and reconstruction of ancient continent. Zircon U-Pb age studies of river sand from the outfall of the Yellow River in Dongying, Shandong Province, together with grain size analysis of detrital components and constituent of heavy minerals, show that the main size of river sand in the outfall of the Yellow River ranges from 10 to 280 μm. Heavy minerals are composed of hornblende, hematite-limonite, garnet, epidote, magnetite, etc. Detrital zircons in the outfall of the Yellow River are igneous origin with multiple populations of ages. The maximum concordant U-Pb age is~3.65 Ga, which reflects the existence of over 3.6 Ga crustal material in the other areas apart from Anshan, Liaoning Province and eastern Hebei Province. Zircon ages mainly distribute in 206-440 Ma, 843-1,239 Ma, 1,476-2,714 Ma, peakings at ~2.5 Ga, ~1.8 Ga and 400 Ma. The two peaks of around ~2.5 Ga and~1.8 Ga show contribution of the North China Block. The 400 Ma peak and ages between 1,000 and 800 Ma represent input materials that came from the Su-Lu Orogenic Belt. Together with previous studies, 2.5-1.8 Ga should be the main growth stage of continent for the provenance crust of the Yellow River's draining area, and over 60% crust was formed at that time.

    Comprehensive Prospecting Model of Tuokesai Lead-zinc Deposit in Wenquan County, Xinjiang
    CHENG Yong,LI Wan-ping,YU Yan-long,YAN Cun-xing, ZHANG Hui,ZHU Sheng-shan
    2013, 27(1):  91-98. 
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    Tuokesai lead-zinc deposit is located in Sailimu block, Yili-Yisaike lake microplate. The ore body hosted in Lower Proterozoic Wenquan group carbonate rock. The ore bearing bed extends steadily and the ore body occurs along the strata with bedded, presented banding and lamellar feature. Leadzinc ore mineral association is simple. On the basis of analysis the genetic type belongs to sedimento-metamorphic deposit which is hosted in carbonate rock. Mining area is located in 1∶200,000 stream sediment survey, metallometry and placer abnormal area. Pb-Zn-Ag composite anomalies are delineated in this area. Pb and Zn as main mineralizing elements have anomalies of large area, high strength, good superposition; and earth's surface lead-zinc mineralization body correspond to these anomalies well. IP scanning mid-low resistance and high polarizability reflect earth's surface and shallow leadzinc mineralization body. Transient electromagnetic measurements for high susceptibility abnormalies reflect deep oreshoot. Based on comprehensive analysis of ore-forming geological conditions, geochemistry and geophysical abnormalies, we establish geological-geochemistry-geophysical prospecting model preliminarily.

    Application of Remote Sensing Technique to Extract Alteration and Linear Structure Information for Resources Prognosis in the Zhulang Periphery Mining Area, Ali, Tibet
    ZHANG Yuan,QIAN Jian-ping,XIE Biao-wu,ZHAO Xiao-xing
    2013, 27(1):  99-107. 
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    Using ETM+ remote sensing data as the basic information sources, remote sensing geological prospecting was carried out in the Zhulang periphery mining area, Ali, Tibet. Remote sensing image was handled by synthesizing pseudocolor, correction and removing the noise. Image filtering was done in order to enhance tectonic information to explain linear structure. The fractal dimension values that were calculated by the method of fractal geometry and the box-counting dimension, and then the linear structures showed excellent statistical self-similarity and fractal characteristics in this area.Principal Component Analysis and Ratio Method were used to enhance the spectrum and space information in this area and to extract the iron-stained and hydroxy alteration information. Comprehensively analyzing fractal dimension value of linear structure, abnormality of altered information, regional geological and geochemical information,and known deposits, five metallogenetic prospective areas were determined. No.Ⅰ prospect area was considered to be one of the most promising area.

    Study on Multi-source Information Metallogenic Prognosis Using GIS in Southern Peru
    XI Zhen, GAO Guang-ming, XIAO Juan, ZHANG Yang
    2013, 27(1):  108-115. 
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    Peru, locating in Andes of South America metallogenic belt, has good metallogenic conditions. Southern Peru is selected to do prospecting area prognosis. Using GIS technology, the geological, mining, aeromagnetic, geochemical and remote sensing multi-source data experienced different processing methods such as relevance analysis, reduction to pole, continuation, principal component analysis, ratio analysis, and so on, then multisource prospecting information also was extracted. On the basis of the above, the prospecting information-content metallogenic prognosis model was built, and 23 important geological variables were selected, then information values and geological complexities were calculated, and eight metallogenic prospect areas were obtained in the end. The experiences of multi-source processing methods and information-content metallogenic prognosis model  are very useful in small scale metallogenic prognosis.

    Extraction of Lithological Information from Bayan Har Mountain Group of East Kunlun Orogenic Belt Using ASTER Image
    SONG Wan-jiao,ZHANG Xu-jiao,GAO Wan-li,HU Dao-gong
    2013, 27(1):  116-123. 
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    The precise division of Bayan Har Mountain Group with complex lithology and widely distributed in the East Kunlun is of great significance to the stratigraphic unit division and structure property analysis. After geometric and atmospheric correction for ASTER images of Bayan Har Mountain in the East Kunlun orogenic belt, the images of principal component analysis(PCA) and band ratio(BR) are obtained by the methods  of lithological information extraction, such as the principal component analysis and mineral index. According to the different images and field geological survey, identification and extraction of Bayan Har Mountain Group lithology information are carried out in the study area. The results show that the upper Bayan Har Mountain Group (T3by) mainly in the south is only divided into two lithology sections because of the unobvious difference of images, which lithology is mainly gray-dark gray silty slate and sandstone. However, the lower Bayan Har Mountain Group (T1by) in the north is divided into four lithology sections instead of the above two sections in the south, i.e. dark gray siltstone and phyllite(section a), gray-green fine sandstone(section b), yellow-brown fine sandstone(section c) and dark gray fine-grained sandstone slates(section d), and the tones and textures of the images are different. The study shows the advantages of extraction of lithological information by using RS in the plateau, and provides a reference for stratigraphic unit division and comparison for Bayan Har Mountain Group.

    Geochemical Significance of FT-ICR MS and Its Application in Petroleum Exploration
    LI Su-mei, MENG Xiang-bing,ZHANG Bao-shou,ZHANG Hai-zu,PAN Na, SHI Quan
    2013, 27(1):  124-132. 
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    Although NSO-compounds occupy only a small portion of crude oil and/or rock extracts, they contain significant geological and geochemical information. The knowledge of NSO-compounds composition was limited by the compositional complexity and the limitations of separation technique. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) coupled with electrospray ionization (ESI) is a recently developed powerful technique for charactering NSO-compounds especially those with high molecular weight in petroleum. ESI FT-ICR MS has been used for petroleum geology application based on its ultra high resolving power and mass accuracy. According to the investigations of the marine and terrestrial oil samples from the Tarim Basin and the Liaohe Western Depression, respectively, as well as other previous works, it has been showed that the FT-ICR MS technique is applicable in multiple geochemical aspects, such as source rock and relevant hydrocarbons determination, maturity level estimation, hydrocarbons migration tracing, and thermochemical sulfate reduction (TSR) identification and/or evaluation. FT-ICR MS is significant in both the compositional characterazation of the NSO-compounds and the application in petroleum exploration.

    Major Oil and Gas Fields Formation Conditions and Accumulation Models of West African Passive Continental Margin Basins
    HU Xiang-yu
    2013, 27(1):  133-142. 
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    Based on plate tectonics, using IHS Energy Information Database and  evaluation data of new projects, starting from the prototype basin research of West African passive continental margin basins, the conditions and main controlling factors of the formation of major oil and gas fields in this area, are systematically analyzed. Three kinds of oil and gas accumulation models of major oil and gas fields are established. West African experienced three prototype stages: Early Cretaceous Neocomian to Barremian intracontinental rift stage, Aptian intercontinental rift stage and passive continental margin stage since Albian, respectively filled by continental facies, transitional lagoonal facies and drift stage marine facies. Intracontinental rift lacustrine facies and drift stage marine facies formed two sets of premium source rocks. Transgressive glutenite facies developed in the early transitional period and carbonatite, delta facies and deep water turbidite sandstone facies developed in drift stage, are high quality reservoirs. Salt rocks developed in late transitional period and marine shale developed during drift stage act as high efficiency regional seals respectively for oil and gas fields beneath and over the salt rocks. Accordingly, we established three kinds of oil and gas accumulation models, which are rift type with little salt rocks in the southern region, double layer type with abundant salt rocks in the middle region and high constructive delta type in the northern region. This research not only deepens the understanding of hydrocarbon enrichment rules in West African passive continental margin basins, but also can help to evaluate new projects in this area.

    Types and Petroleum Geology Characteristics of Onshore Basins in Brazil
    PANG Zheng-lian, FAN Tai-liang, HE Hui, WANG Jin-cai, NIU Min
    2013, 27(1):  143-151. 
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    Based on basic geological conditions of onshore basins in Brazil and the theory of petroleum geology, basin types are classified and petroleum geological characteristics of different types of basins are studied with methods of analogy and analysis. South America platform underwent a complex tectonic evolution history, and three types of basins formed in Brazil, including Proterozoic superimposed basin, Phanerozoic craton basins, and Mesozoic failed rift basins. Proterozoic superimposed basin is characterized by its ancient strata, complex tectonic evolution history, Proterozoic source-reservoir-cap assemblages, and long thermal evolution history of source rocks. The similarities of the Phanerozoic craton basins are the evolution of “from rift to depression”, Paleozoic main sequences, one set of widespread source rock, and the generation and expulsion both influenced by intrusive rocks. In Mesozoic failed rift basins, both basic and petroleum geology are characterized by the features of rifted lacustrine basins. Through the research in regional evolution, classification, strata and tectonic characteristics, source rocks, reservoirs, cap rocks, and petroleum accumulation of these onshore basins, we hope the information mentioned above can be a reference in the nation's oversea targeting strategies.

    Structural Evolution and Hydrocarbon Accumulation of Balizhuang-Xuezhuang Buried Hill Belt in Jizhong Depression
    ZHA Ming,WEI Ya-min,GAO Chang-hai,QU Jiang-xiu
    2013, 27(1):  152-157. 
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    Balizhuang-Xuezhuang buried hill belt is a typical fault-block buried hill belt in Jizhong Depression. The paper analyzes the forming and evolution process of Balizhuang-Xuezhuang buried hill belt by seismic and drilling data for the structural characteristics and reservoir-forming conditions. The results indicate that the evolution process of Balizhuang-Xuezhuang buried hill belt is divided into four phases. The first phase is the development of buried hill material from Meso-Neoproterozoic to Palaeozoic. The second phase is the forming of buried hill rudiment in Mesozoic. The third phase is the main development and formation of buried hill in Early Teriary. The last phase is the deep burial period of buried hill from Neogene to Quaternary. The tectonic events in Balizhuang-Xuezhuang area can be treated as the most important factor for evaluating hydrocarbon bearing potential in buried hills, due to their domination in oil resources, reservoir conditions, transporting conditions, trap-reservoir types in Balizhuang-Xuezhuang buried hill belt.

    Tectonic Analysis on Aqia Fault Belt in the Western Tarim Basin
    LIU Ya-lei,QI Ying-min,LIU Yun-xiang,WANG Yue-ran,ZHAO Yan,ZHANG Qiang
    2013, 27(1):  158-164. 
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    The Aqia fault belt, which occurs as the boundary of the Awati Sag and Bachu Fault-Uplift in the western Tarim Basin, is mainly made up of Aqia fault and Qiaolaimaiti fault. Based on seismic interpretation, it can be divided into three parts: the west, the middle and the east sections. The west section is a single basement-involved thrust fault which dips towards the Bachu Fault-Uplift. Comparatively, the middle section has a Y-shape tectonic style and begins to show the wedge-shaped thrust features, which develops not only the main Bachu-inclining fault mentioned above, but also a recoil fault with a reversed inclination. In the east section, the main Bachu-inclining fault stopped growing at Mid-Cambrian, with the displacement above completely absorbed by the Awati-inclining recoil fault, which finally forms the typical wedge-shaped thrust structures. A series of Quaternary normal faults have developed on the upper fault plate in the west and middle sections. According to the research, we conclude that there exist mainly two stages of fault tectonics in the Aqia fault belt: the deep basement-involved thrust fault zone and the shallow overlaid normal faults series. The former started to form in Early Neogene and finally stabilized in Late Neogene; the latter is a new discovery in this paper which formed in the Early-Middle Quaternary and it developed only in the west and middle sections of the Aqia fault belt.

    Natural Gas Origin and Accumulation Stages of the Third Member of Feixianguan Formation in Western Hubei and Eastern Chongqing Area
    SHU Zhi-guo
    2013, 27(1):  165-171. 
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    The third Member of Feixianguan Formation (T1f3) is the main gas producing formation of marine carbonate strata in western Hubei and eastern Chongqing area. Systematic research on natural gas accumulation stages and main controlling factors should be helpful for natural gas prospecting in this area. Based on natural gas composition and stable carbon isotope, kerogen carbon isotope, and homogeneous temperature of fluid inclusions data, this paper discussed the origin and source of the natural gas, hydrocarbon generating and petroleum charging history. Finally, gas accumulation stages and the main controlling factors of gas accumulation were analyzed according to the regional structure and local trap evolution histories. Following conclusions can be drawn. The natural gas of T1f3 was mainly secondary cracking gas of the crude oil generated from the Permian source rock. Natural gas accumulation can be divided into three stages: oil accumulation of paleo-lithologic reservoir (190 Ma to 160 Ma), oil cracking and gas accumation of the paleo-lithologic reservoir (160 Ma to 140 Ma), and present structural-lithologic gas reservoir formed by the reaccumulation and adjustment of gas (140 Ma to present). The scale of the exposure shoal reservoir effects the scale of paleo-oil reservoir, and the reservation condition during the natural gas remigration and accumulation should be vital for the final gas accumulation of present gas reservoir.

    Oil Migration and Accumulation Pattern of Putaohua Reservoir in Two Wings of the South of Daqing Placanticline
    XIAO Dian-shi, LU Shuang-fang, HUANG Zhen-kai, CHEN Hai-feng, WANG Na
    2013, 27(1):  172-179. 
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    Putaohua reservoir is rich in oil and gas resources in the two wings of the South of Daqing Placanticline. The discovery rate of resources was low and proved reserves producing effect was poor in the two wings, because of complex oil/water distribution and inadequate understanding oil and gas accumulation pattern. Based on the detail oil-source correlation, through marking the oil-migrating faults with faults classification and analyzing the control of the allocation of faults and sand bodies to hydrocarbon migration and accumulation, the pattern of reservoirs forming is established in this paper. It's considered that the oil of Putaohua reservoir mainly comes from the local hydrocarbon source rock of K1qn1, and the key period of hydrocarbon expulsion is the late sediment stage of K2m and later. Consequently, the main oil-migrating faults are composed of two types:(1)faults forming in depression period and faulting in inversion period; (2)faults forming in faulted period and faulting in depression period and inversion period. The oil vertical migration to Putaohua reservoir happened along the oil-migration faults, and the distance of oil lateral migration was short because of the restriction of sand bodies scales and fault lateral sealing. Thus, the oil-migrating faults are main control faults of the reservoir, which control the oil/water distribution at plane, and the allocation of the oil-migrating faults and sand bodies controls the horizon and range of oil accumulation. The favorable area of hydrocarbon accumulation is high fault blocks next to the oil-migrating faults, including the footwall of oil-migrating faults, inversed fault terrace, monoclinic horst, and forward fault terrace.

    Petroleum Accumulation Characteristics and Favorable Exploration Target of Silurian in Tahe Oilfield
    FENG Xing-qiang, ZHANG Zhong-min, ZHANG Wei-biao
    2013, 27(1):  180-185. 
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    The Silurian reservoir is advantageous for hydrocarbon accumulation and shows its richness in crude oil and gases in Tahe oilfield. The Silurian reservoir properties in general have medium-low porosity and permeability, and the overlaying shale form 3 sets of reservoir-cap assembles. The oil-gas reservoir types include anticline, stratigraphic, lithological and compound oil and gas reservoirs. The research indicates that the Silurian hydrocarbon accumulation characteristics are multistage charging and multistage hydrocarbon accumulation. The main periods of hydrocarbon accumulation are Late Caledonian, Hercynian and Late Himalayan. The formation and distribution of oil and gas pools are controlled by many factors, which include structure, development degree of fault, and high-quality reservoirs. The south part of Tahe oilfield is favorable area for tectono-stratigraphic reservoir exploration. The Tuoputai area of Tahe oilfield is favorable region for primary pool.

    Provenance Analysis of ZaoⅢ Reservoir Group in Southern Kongdian of Huanghua Depression
    ZHANG Shi-jie,PU Xiu-gang,LI Yong,YAN Zhao-kun,QIAN Geng,QIU Dong-zhou
    2013, 27(1):  186-190. 
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    In order to depict the provenance system of ZaoⅢ reservoir group in southern Kongdian region and predict the sand-body distribution between Zaoyuan and Wangguantun development zones, as well as to promote further exploration and provide a theoretic base for development, Comprehensive application of geophysics, geochemistry and sedimentology to depict precisely the provenance system in ZaoⅢ period is needed. By comprehensive research of regional gravity anomaly, seismic attribute, heavy mineral cluster analysis, light mineral analysis, analysis of debris, and sand-body dispersions system in southern Kongdian, Huanghua Depression, six fans were described precisely in western Cangxian uplift, northern Kongdian Salient and eastern Xuhei Salient. To integrate the relationship among the provenance system, the strata, ancient landform and the structure characteristics, the provenance system in ZaoⅢ period of Kongdian group in southern Kongdian region of Huanghua Depression is controlled by ancient landform characteristics, synchronous fractures and basin margin bedrock.

    Sedimentary Facies and Sedimentary Systems Evolution of Shahejie Formation in Peripheral Regions of Bodong Buried Hill, Dongying Sag
    YANG Yong-qiang,QIU Long-wei,ZHANG Xiao-dan,WANG Xin-zheng,CAI Hong-xing
    2013, 27(1):  191-199. 
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    Based on the seismic survey, logging data and core, this paper analysizes the development characteristics of the Shicun fault and its controlling effect on the evolution of the Bodong buried hill, and studies systematically the sedimentary facies types of the Shahejie Formation for the first time. The research shows that the evolution of the Bodong buried hill is controlled by the Shicun Fault. The rapid uplifting of the Bodong buried hill affects the sedimentary geomorphology on both two sides in the Es4 and the lower Es3. However it has a weak effect on the upper Es2 and the layers above. During the sedimentary period when the upper part of the fourth Member of Shahejie Formation deposited and when the lower part of the third Member of Shahejie Formation deposited, here mainly developed delta front subfacies, prodelta subfacies, beach bar and organic bank deposition of lakeshore-shallow lake subfacies, semi-deep lake deposition and deep lake deposition. During the sedimentary period between the middle part of the third Member of Shahejie Formation deposited and the first Member of Shahejie Formation deposited, here mainly developed delta front subfacies, prodelta subfacies and organic bank deposition of lakeshore-shallow lake subfacies and so on. Under the influence of the Shicun fault and the Bodong buried hill, facies differentiation of the North and South wings can be seen in the early stage (the Es4 and the upper Es3) while the same in the late stages (the lower Es2 and the Es1).

    Characteristics of Pore Types, Structures and Classification of Volcanic Rocks in Cenozoic of Qikou Sag, Huanghua Depression
    WANG Nai-jun,LUO Jing-lan,GUO Yong-feng,LI Shuang-wen,LIU Hua-qing
    2013, 27(1):  200-207. 
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    The pore types and structures of volcanic rocks in Cenozoic of Qikou Sag, Huanghua depression in Bohai Bay Basin  were researched using a large amount of data from core observation, ordinary slices, cast slices and the hydrargyrum injection experiments, and the pore structures were classified and evaluated. The results indicate that the pores of volcanic rocks include primary and secondary pores. The primary pores include stomatas, residual stomatas, inter-gravel pores and primary fractures, and the secondary pores include dissolved pores (holes, fractures), structural fractures and weathering fractures. The diabase has larger pore and throat, worse sorting and better connectivity; the basalt has middle pore and throat, moderate sorting and worse connectivity; the tuff has smaller pore and throat, better sorting and moderate connectivity. Pore structures of reservoirs are divided into five types: types of Ⅰ and Ⅱ are better reservoirs, which are dominated by diabase and tuff; type Ⅲ stands moderate, which is mainly diabase and secondly basalt; type Ⅳ is the worst one, which is mainly diabase; type Ⅴ is nonreservoir, which is mainly tuff. Type Ⅲ has the highest proportion with a rate up to 52%, followed by type Ⅱ, and types ofⅠ, Ⅳ and Ⅴ have smaller proportion.

    Genetic Mechanism of Low-permeability Reservoir of Yingcheng Formation in Lishu Fault Depression,Songliao Basin
    XI Ke-lai,CAO Ying-chang,CAI Lai-xing,ZHOU Lei,YANG Chun-yu,WANG Jian
    2013, 27(1):  208-216. 
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    The main rock types of Yingcheng Formation in Lishu Fault Depression of Songliao Basin are arkose and lithic arkose. The result of reservoir physical property test showed that reservoir physical properties are poor in this area, which have characteristics of low to ultra-low porosity and special low to super-low permeability. This paper analyzed the low-permeability reservoir's characteristics and its property controlling factors by utilization of core observation, thin section identification, image analysis, mercury testing and other technical methods. The main reservoir pore spaces are primary, secondary dissolution pores and a small amount of mixed pores. The diagenetic types of the reservoir are compaction, dissolution, cementation, metasomatism, and so on, and the diagenetic evolution sequence is compaction→feldspar and debris dissolution→carbonate cementation→carbonate dissolution. Thus the sedimentation and diagenesis coupling relationship determines the quality of reservoir properties. On the basis of the above, the inversion method of back stripping was used to recover the reservoir properties and its evolution history during the geological time under the constraint of reservoir diagenesis evolution sequence and reservoir pore structure. The results show that the low-permeability reservoir's physical properties are fundamentally controlled by deposition, moreover, the low-permeability characteristics are predominated by compaction and enhanced by cementation.

    A Novel Design Method for Stimulated Reservoir Volume Fracturing in Shale Horizontal Wells
    GOU Bo, GUO Jian-Chun
    2013, 27(1):  217-221. 
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    The technology of the stimulated reservoir volume(SRV) fracturing are often used in shale horizontal wells to obtain deliverability. The fracture network volume and permeability are critical to postfracture response. The design for SRV employs productivity prediction model which is complex and inconvenient in application to optimize fracture network parameters at present. The relation model between the fracture network parameters and hydraulic fracturing treatment sizes is established with the fracture network equivalent to a high permeable zone by using the principle of seepage rate equal effects. The method and steps for SRV in shale horizontal wells are put forward also, including feasibility study about SRV in shale reservoir, optimizing fracture network parameters in numerical simulation and treatment sizes. According to the characteristics of QY2 shale oil horizontal wells, the new design method is implemented. The result shows that the high permeable zones have the biggest contribution to flow potential in shale wells, and the cumulative production and degree of reserve recovery increase slowly with the augment of clustering number, volume, permeability of the high permeable zones. There exsit the optimal high permeable zone's parameters. Field application shows that the design method is convenient and can be generalized to other shale horizontal well fracturing design.

    3D Seismic Chimney Detection Technology Based on Dip Steering and Its Application on Buir Sag of Hailar Basin
    YANG Rui-zhao,LI Yang,PANG Hai-ling,ZHAO Zheng-guang,WEN Xiao-long,
    2013, 27(1):  223-230. 
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    The gas chimney is a special associated structure formed by the hot fluid flow in the sedimentary basin. As a specific channel for oil and gas migration, the gas chimney is a direct evidence for the existence of shallow reservoirs, and it can also influence hydrocarbon accumulation. These days, many scholars have paid attention to gas chimneys. Based on the research results and thoughts about gas chimneys home and abroad, through the artificial neural network (ANN) which is based on multi-layer perceptron and provided by the brand new seismic solution, i.e.OpendTect, this paper predicts the probability of occurrence for gas chimney, improves the algorithm by using dip steering, presents and applies seismic chimney detection technology based on dip steering. The application of pattern recognition technology in seismic exploration field has been well supplemented and developed. Generally, the 3D seismic chimney detection technology can not only interpret the migration pathway and reason of shallow gas accumulation, but also forecast the development of source rocks. In addition, it is also applicable for distinguishing fault sealing. At last, this process was applied to research the migration pathway and accumulation rules of an oil-bearing block in Buir Sag of Hailar Basin, and the fracture characteristics and types of migration pathways were put forward, then the special configuration relations of oil source, pathway, reservoir and cap rock were summarized, and the corresponding accumulation mode was  established.

    Oil and Gas Indications at Gas Hydrate-bearing Intervals in the Qilian Mountain Permafrost
    LU Zhen-quan, ZHU You-hai, LIU Hui, ZHANG Yong-qin, WANG Ping-kang, HUANG Xia
    2013, 27(1):  231-238. 
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    In this paper a case was set in the gas hydrate drilling hole of DK-2 in the Qilian Mountain permafrost. Oil and gas indication-bearing core samples were analyzed with reservoir pyrolysis, and in combination with field observation of oil and gas indications, the nature of oil and gas indications and their possible indicative implication to gas hydrate were discussed. The field-observed oil and gas indication phenomena such as various kinds of oil trace, oil patch, oil immersion and oil staining, mostly occurred within fine sandstone, medium sandstone, and partly on interfaces between silt mudstone and carbonate lamina or within their fissures, which were proven by indoor reservoir pyrolysis results. The nature of oil and gas indications showed that the crude oil was mainly composed of medium-weighted oil or heavy-weighted oil with minor over-heavy-weighted oil and even with asphalt. In the drilling hole, the oil and gas indications were closely associated with gas hydrate, and especially those characterized by medium-weighted oil within or just below gas hydrate occurrence interval could be a sign for gas hydrate occurrence.