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    25 December 1980, Volume 1 Issue 3
    DIWA-TYPE OIL AND GAS FIELDS IN CHINA
    Chen Guoda, Fei Baosheng
    1980, 1(3):  167-176.  doi:10.11743/ogg19800301
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    According to conventional oil-forming theories,the oil and gas fields can be only occurred in two types of geotectonic conditions,i.e.geosyncline-type and platform-type basins.Based on the practical experiences and the geological contributions available,the authors have suggested a new geotectonic systematics of oil and gas fields in China,using the diwa(geodepression)theory of oil formation.While dealing only with the diwa-type oil and gasfields which spread most widely in China and have great economic significance,attention is drawn to their basic characteristics and distribution regulari-ties in order to show a guidance to petroleum searching.Both of oil and gas fields formed in an environment of activated and inactivated platforms,as well as in that of geosynclines in China,have already been discussed in other papers.

    ON INDICATIONS OF SEDIMENTARY ENVIRONMENTS OF THE LUAN RIVER SYSTEM AND THE BEIDAIHE COAST
    Zhen Junmao, Sun Yongchuan, Wang Defa, Li Huisheng, Wang Shifeng
    1980, 1(3):  177-190.  doi:10.11743/ogg19800302
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    The characteristics of sediments,such as their sequences,particle-size dis-tribution,constituents of minerals and detritus and the surface features ofquartz grains,are discussed here with respect to environments relative to the upper tributaries,braided channels of the upper-middle reach,meander-ing channels of the middle-lower reach and the deltaic distributary-monthbars within the system of Luan drainage,as well as to the coastal beach,the coastal dume and the beach of the Beidaihe cliffed coast.This study shows that sediments from individual environments mentioned above are different and,therefore,their features can be used for identifying environments of sedimentation.The diverse environments are characterized by apparent different cumulative probability curves.The constituents of minerals and detri-tus derived from the same source area are functions of transport distance andcurrent agent,especially when they are of unhomogeneous nature.The surfacefeatures of quartz grains are indicative of environments of sedimentation,e.g.of aeolian,marine and fluvial conditions.This study suggests that Luanriver is a middle-small,seasonal and sand-rich one of short source.There-fore,its sediments are abundant in sands with only a few of mud interca-lations.The sand grains is coarse and,in addition,there are gravels andmud gravels at the base of section,the content of minerals is less than thatof detritus,with maturity being lower.The dune is well deveoped on banksof the stream and this demonstrates that the wind may be strong enough during the dry season.The delta is resulted primarily from the agent ofstream,but certain tidal action may also be involved.The sediments on the beach near the Luan river mouth are distinct from that on the beach ofBeidaihe cliffed coast due to the distinction between them.

    CHARACTERISTICS OF INFRARED SPECTRUM OF CRUDE OIL AND ITS GEOLOGICAL INTERPRETATION
    Lin Dengzong
    1980, 1(3):  191-206.  doi:10.11743/ogg19800303
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    The infrared absorption spectrometer is a powerful tool for detecting functional groups of organic compounds and analysing their molecular struc-tures.Since sixties,this tool has been adopted into areas of petroleum geology and a great quantity of data were achieved.A lot of facts demons-trate that the infrared spectrum of crude oil from various districts or differ-ent horizons exhibits both common and peculiar features,and it indicates some difference in geological settings.The main factors that lead to the above difference in properties of crude oil in China proper are as follows:(1)Source bed which may be of sapropelic or humic type;(2)Sedimentary and oil-generating environment which may have affectedon conservation,trans formation and maturity of organic substances;(3)Epigenetic changes of crude oil which may account for subsequente volution,oxidation,biological and physical processes.Majority of oil fields in China discovered now are concentrated in Mesozoic and Cenozoic continental basins,thus the source beds mostly are of mixed sapropel-humic type.The crude oil generated contains generally more high-molecular paraffin,aromatic and polycyclic naphthenic hydro-carbons and,moreover,was not deeply buried,but well concealed and underwent only a little of epigenetic alteration All these account for the displaying high absorption peaks of its infrared spectrum for high mole-cular paraffin and aromatic hydrocarbons.However,in places where it was deeply buried or the ancient geotherms were higher,it underwent to a cer-tain degree modification and therefore shows an infrared spesctrum oflight crude oil.Depending on geological setting of petroleum productive basins,the crude oil of individual basins may possess different infrared spectrum.In the continent of our country,there are relatively small amountsof oil and gas fields in marine sediments.The source beds generally are of sapropelic type and the crude oil derived there from is represented chiefly by alkanes and naphthenes which have lower molecular weight,but the aromatic hydrocarbon and high-molecular paraffin are rarely cantained.Further more,because of its aging,being deeply buried and extensive modi-fication,it usually has infrared spectrum with a nature of light crude oil which accounts for more intensive absorption peaks for methyl,methy leneand lower molecular alkanes and indistinct absorption peaks for aromatic hydrocarbon and heterocyclic compounds.Local crude oil maintains solidparaffin or has become oxidized heavy oil with entirely different infrared spectrum.

    TERTIARY FORAMINIFERAL FAUNAS OF CHINA AND THEIR SIGNIFICANCE IN OIL & GAS PROSPECTING
    Qiu Songyu, Lin Jinxing
    1980, 1(3):  208-219.  doi:10.11743/ogg19800304
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    Based on their compositions and characteristics as well as resemblanceand difference between the most abundent genera and spicies,six foramini-feral faunas are recognized,namely:1.the Discorbis fauna,2.the Nummu-lites fauna,3.the Cibicides fauna,4.the Orbulina-Miogypsina fauna,5.the Ammonia fauna and 6.the Pulleniatina-Asterorotalia fauna.The firstthree of them belong to the early Tertiary while the last three to the late Tertiary.The Discorbis fauna are mainly found in many places of East China,suchas the Bohai gulf,the Jianghan basin,the north part of Jiangsu province,the Sanshui basin,etc.The Ammonia fauna are mainly reported from the W.Tarim basin.As they may tolerate some lowering of salinity,they serveas important facial indicators in searching for oil and gas reservior of brackish-water origin.The Cibicides fauna and the Orbulina-Miogypsina faunacomprising entirely shallow marine and pelagic genera play an improtant rolein prospecting for oil and gas reservior of epeiric origin.The Cibicides faunais discovered from the S.W.border of Tarim,while the Orbulina-Miogy-psina fauna has much wider distribution in Taiwan province and the Leiqiong region of Guangdong province,and on the continental shelf of the South and East China Seas.

    THE STAGES OF NEOCATHAYSIAN’S GENERATION AND THEIR CONTROLS OF OIL AND GAS
    Zhang Fuli
    1980, 1(3):  220-228.  doi:10.11743/ogg19800305
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    On the basis of the shifts of continental margin since Mesozoic time and the patterns of stress action during tectonic movements in the areas of the east China and the eastern Asia as a whole,it is suggested that the Neoca-thaysian Systems were generated after Whaiyang movement which took placeat the ead of middle Triassic,and now these Systems occupy a broad terri-tory.east of the north-south tectonic structures,extending from Mt.Helan through Mt.Longmen to central Yunnan.Properties in stages of generation and development of Neocathaysian Sys-tems,principles of their division and controls of oil and gas are the primarypoints required to be discussed in this study.According to data on sedimentation,structures and tectonic movements,the process of development of the Neocathaysian Systems can be divided into three stages,namely:①La-te Trissic-Jurassic,②Cretaceous-Paleogene,and ③Neogene-Quarternary.For the purpose of petroleum geology,it is considered to be necessaryto distinguish the primary sedimentary basins from the later ones in orderto have a good knowledge of the process of generation of different subsidence regions and it is emphasized that of prime importance are controls occur redunder a variety of conditions,such as ordinal or seguencial controls by various degree of tectonic structures,composite controls by the same tectionic stru-ctures aud composite controls by different tectonic structures.Finally,thebasic features of oil and gas controls by stages of Neocathaysian Systems arealso discussed thereafter.

    CHARACTERISTICS OF SOLID BITUMEN AND LIQUID HYDROCARBON IN ZIGUI AND DANGYANG BASINS,HUBEI PROVINCE
    Wang Tieguan
    1980, 1(3):  229-240.  doi:10.11743/ogg19800306
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    Dark solid bitumen associated with silicified wood and carbon scraps or coal string was found in many places in continental Jurassic basins in thewestern Hubei province.For a long time,people took it for“coal”or“seepage”.Through surveying and research of the solid bitumen in Zigui,Dangyang basins,it was identified that it belongs to the derivative from humic typeof solid and liguid hydrocarbons.It can be called coal bitumen,because it soccurrence,distribution,organic component and stnucture all show a geneticre lationship with coal and humic type of source bed.Study of the humic type of coal bitumen indicates that the oil could be“generated”indeed during the process of incoalation.However,the liguid hydrocarbon of humic type and its derivative are a kind of heavy and vis-cous fluid characterized by high content of non-hydrocarbons and aromatichydrocarbons,which is difficult to move through a long distance,and unfa-vourable for accumlation of hydrocarbon.Therefore,its distribution is inscareity.Furthermore,its“oil-generated amount”is limited too,and it isnot suitable in our practical works to consider all sorts of the solid bitumenas sapropelic type of petroleum bitumen,and it is necessary to here solidbitumen to be genetically classified in order to give a correct assessment.

    EXISTENCE OF MERCURY IN GASES FROM BIYANG BASIN,HENAN PROVINCE
    Tu Xouyan
    1980, 1(3):  241-247.  doi:10.11743/ogg19800307
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    The mercury vapour shows clearly a good similarity to gases derived from oil and gas fields in aspect of their migration and accumulation.Therefore,its existence in these gases is not only related to the nature of the.crude oil,but also depends on the geological setting.The mercury vapour generally has relatively high penetrative ability and it can constitutean anomalous distribution in soil,while moving upwards from oil-gas reser-voir and arriving at the earth surface.Systematic measurements of mercury vapour were carried out in 1979 over two oil fields in the Biyang basin,after a test analysis of the geochemical features of mercury vapour overvarious places of Huabei,northern Jiangshu and Jianghan basins,and it isproven that there ate indeed mercury anomalies which exist over oil fields.Thus,this can be used as a new parameter for the oil and gas prospecting.A correlative analysis of data available reveals further that thecontent of mercury in natural gases is in function with some factor srelevent to oil productive horizons.A predominent detection conforms thatthe content of mercury vapour has apparently a positive relationship with temporature,depth and static pressure of oil productive horizons,but negativere lationship with gas/oil ratio and quantity of waters in crude oil.

    A PRELIMINARY STUDY ON THE STRATA IN THE EARLY PART OF THE LATE CRETACEOUS IN THE LIUCHE AND JIAN BASINS,JIANGSI PROVINCE
    Cai Jun
    1980, 1(3):  248-251.  doi:10.11743/ogg19800308
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    After a comprehensive analysis of fossils from the Zhoutian formationof the Liuche basin in Xunwu county and from the Zhixia formation of the Jian-Taihe Basin,Jiangsi province,and after a comparison of these two formations with the Qujiang group(members 1—4)of the adjacent Jinhua-Quxian basin,Chejiang province,the author considers that both formations belong to the early part of the Late Cretaceous in age.