1986 Vol. 8, No. 4

Display Method:
THE EXPLORATIONAL PROSPECTS OF NON-STRUCTURAL OIL/GAS POOLS IN MARINE FACIES STRATA OF SICHUAN PROVINCE
Chen Zongqing
1986, 8(4): 301-312. doi: 10.11781/sysydz198604301
Abstract:
The source potential (productivity) of hydrocarbons estimated for the marine facies strata of Sichuan Province differs greatly from the hydrocarbon reserves calculated in respect of the structural oil/gas pools.Therefore,the amount of migrated hydrocarbons can be hundreds times of that of commercial hydrocarbons in the present structural trap.Obviously,though a part of hydrocarbons generated has been dispersed through outcrops and destroyed structural traps,other parts of the hydrocarbons would be preserved in non-structural traps.It is believed that the following types of oil/gas pools would be promising.1.Ancient burial hills and stratigraphic overlaps in Leshan-Longnuzhi Ancient Upheaval (Lower Paleozoic systems);2.Structural-lithologic (stratigraphic) complex in Longmenshan Tran-sitional Zone (Devonian System);3.Stratigraphic overlaps and relic hills in the eastern part of Sichuan Province (Carbonifeous System);4.Non-structural traps in Permian dolomites of reef and reef bank facies formed due to mixing of fresh and brackish water;5.Reef facies dolomites of Changxing Formation.6.Reef bank facies dolomites of Yangxing Series for which much attention should be paid to erosional surface at the top of Yangxing Series;7.For Triassic systems,not only lithologic traps in the oolite limestones of Feixiangan Formation,the coarsely textured carbonates of Jialinjiang Formation,and the oolite and algal dolomites in Leikoupo Formation are petroliferous,but also the stratigraphic overlaps in Luzhou-Kaijiang Ancient Upheaval Zone is important.As viewed from the methodology of petroleum explorations,both the precision and reliability of seismic exploration should be improved and integrated interpretation should be carried out.In addition,the drilling and geological researches should be reinforced.
A PRELIMINARY STUDY ON THE ERLIAN BASIN CHARACTERISTICS FOR STRUCTURAL PETOLEUM GEOLOGICAL
Wang Tonghe
1986, 8(4): 313-324. doi: 10.11781/sysydz198604313
Abstract:
Erlian Basin is a faultdown basin situated in Variscian folded region,in which the thickness of the earth crust is thinner,geothermal gradient is higher,and volcanic activity is frequent.The basin is divided into wide and elongate hosts and narrow and deep grabens.They arranged en echelon and the fills of the basin belong to continental facies,because of their faster depositional rate.The lithofacies and its thickness changed rapidly,but the cycle of depositional sequences is clear.In the basin,the source beds,reservoirs and seals are good,and the conditions of traps are distinctive.Combinations of them are excellent in both space and timing.Consequently,there is a good oil-bearing prospect in the basin.Erlian Basin will be explorated as a new energy base.Therefore,the study on the structural characteristics is important for increasing the reserve of energy and developing petroleum geology knowledge.
DISCUSSION ON GAS POOLS OF MIXED ORIGINS AND THE CONTROLLING FACTORS
Dai Jinxing
1986, 8(4): 325-334. doi: 10.11781/sysydz198604325
Abstract:
Based on the analyses of various isotopic compositions (δ13C113Cco2,40Ar/38Ar,etc.),it is suggested there arc not only natural gases of single origin,but also gases of mixed origins.According to the isotopic composition studies of He,Ar and C,the constituents of He,Ar and N2 in Sinian weiyun Gas Field are pertained to inorganic origin coming from deep parts of the crust,whereas it can attributed to thermogenic gas because the isotopic values of the hydrocarbons are of -32.6‰— -32.9‰.As another example,the gas of Wanjints Gas Field has values of δ13Cco2 range from -4.04‰ to -8.83‰ which proves the inorganic origin of the CO2 (volcanic source) whereas δ13C1 value is of -42.07‰ to -45.37‰ which indicates the organic origin of the methane.The various origins of the different constituents of the same gas pool (shows) indicate not only the complex processes for the accumulation and formation of natural gas,but also the complication of the gas and source correlations.
DISTRIBUTION AND GENESIS OF NATURAL GAS IN SOUTHERN SONGLIAO BASIN
Xu Duichang
1986, 8(4): 335-343. doi: 10.11781/sysydz198604335
Abstract:
Taking the petroleum geolgy of the southern Songliao Basin as background,based on the geological and geochemical condition of the generation of natural gas,this paper studies the analytical data of 320 gas samples and finds out that the natural gases of the southern Songliao Basin could be divided laterally into districts and vertically into zones.According to the organic geochemistry characteristics,four genetic types of gases are recognized.Furthermore,the favourable areas and the guideline for natural gas exploration in southern Songliao Basin are pointed out.
THE UNCONFORMITY BETWEEN CRETACEOUS QINGSHANKOU FORMATION AND QUANDOU FORMATION OF SONGLIAO BASIN AND ITS SIGNIFICANCE IN PETROLEUM GEOLOGY
Zhou Zhengnan
1986, 8(4): 344-350. doi: 10.11781/sysydz198604344
Abstract:
For long time,it is believed that there is a conformity between Cretaceous Qingshankou Formation and Quandou Formation of Songliao Basin with continuous transition.Based on detail analyses of stratigraphic correlation,lithology,and lithofacies,especially with the increasing seismic data to interpret the five seismic profiles across the different structures of the basin,it is proposed there is an unconformity between the two formations resulted from uplifting movements.The T2 seismic reflection is defined as a contact boundary between the two formations.It is suggested that the unconformity would exert influence on the migration and accumulation of petroleum.So that effort should be made in searching stratigraphic oil/gas pools and related structural traps above or below the unconformity.
THE STORM DEPOSITS AND CHANNEL FACIES IN GUANSHAN FORMATION, WUTONG GROUP FROM SOUTH JIANGSUAND EAST ANHUI
Wu Xiantao, Hu Bin, Wang Guanzhong, Zhang Guocheng, ZhuGe Zhixiang, Mu Rikong, Qian Qing
1986, 8(4): 351-361. doi: 10.11781/sysydz198604351
Abstract:
The sedimentary environments of Guanshan Formation in South Jiangsu puzzled the geologists for decades because of lacking identifiable body fo-ssils and other depositional features in the sandy deposits.But both trace fossils and sedimentary structures are abundent after carefully looking into the well displayed section in Kongshan,Jiangsu and Taihushan,Auhui.In contrast to the previous studies,seven clastic shoreline depositional types have been recognized in the region for the first time.The first depositional type is intertidal bar,which is characterized by herringbonecross-bedding and swash cross-bedding as well as reverse graded bedding;The Zndtypeof Submerged bar is composed of quartz fine grained sandstone at the lower part,planar cross-bedding in the middle and follo-wed by troughcross-bedding and reverse graded quartz sandstone at the top.The 3rd type is recorded by storm surge deposits of basal lag Pebbles,graded coarse sandstones and suspension deposits of mud layers after the storm was over.This depositional type is suggested to be produced in an area near the fair wheather wave base.The fourth sandy depositional type of the studied district contains lag conglomerates,two clay layers and trace fossils of Arenicolites implying a shallow subtidal channel origin.Finally,the fifth one of deposition has lower subunit of medium to coarse grained sandstones with pebbles,and middle subunit of large planar cross-bedding and herringbone cross-bedding,as well as thin bedded fine to medium grained sandstones alternating with sandy mud layers in which trace fossils of Arenicolites,cf.Cruziana have been found.The sedimentary texture,structure and biogeneic structure imply its sedimentary environment were of deep subtidal channel.
THE DISCOVERY OF ORGANIC NANOFOSSILS IN AMORPHOUS KEROGEN OF LOWER PALEOZOIC SOURCE ROCKS, SOUTHERN MARGIN OF YANGTZE PARA-PLATFORM, AND ITS SIGNIFICANCE IN PETROLEUM GEOLOGY
Qiu Yunyu, Xi Ketang, Wu Di
1986, 8(4): 362-365. doi: 10.11781/sysydz198604362
Abstract(1145) PDF-CN(267)
Abstract:
Under scanning electron microscope with an amplification of 5,000-10,000 X,organic nanofossils of marine primitive organisms have been discovered for the first time.They are found in the amorphous kerogen of Lower Paleozoic black claystones of deep water basinal facies and darkgrey impure carbonate rocks of deep water shelf facies at southern margin of Yangtze Para-platform.It is suggested that they belong to a new kind of organic nanofossil.This discovery not only provides direct information for deviding the types of source material and for characterizing its components in this highly mature area,filling up the blankness of such a kind of study,but also adds new data to the study of paleo-environment,paleo-geography and organic facies.This discovery changes the traditional concept,and reveals the actual aspect of source material.
ANALYSES ON THE PHASES OF GAS WELL TESTINGS FOR CARBON DIOXIDE
Zhang Chuanru, Hu Chengxian, Dai Yifu, Dian Xiangai
1986, 8(4): 366-373. doi: 10.11781/sysydz198604366
Abstract:
Based on CO2 T-S diagram,the phases of gas well testings are analysed in this paper,and the CO2 deviations and the errors of the flow meters for CO2 critical speeds are discussed in details as well.
1986, 8(4): 374-374. doi: 10.11781/sysydz198604374
Abstract:
THE DISTRIBUTIVE CHARACTERS OF TRACE ELEMENT IN OILFIELD WATER OF BIYANG DEPRESSION AND ITS RELATIONSHIP TO OIL AND GAS
Zhu Yanyun, Yang Xuelian
1986, 8(4): 375-385. doi: 10.11781/sysydz198604375
Abstract:
Through the systematic analyses of 194 water samples from the oil fields in Biyang Depression,the relationships of the trace elements to the depositional environments,and hydro-geochemical zonation are studied.Then,the oil and source rocks are correlated in order to trace out the direction of oil and gas migration.Thereafter,the accumulation and distribution of oil/gas are inferred that it would undoubtedly provide some helpful informations for petroleum exploration.
ANALYSIS OF AC CARBONATE IN SURFACE SOIL AND ITS APPLICATION TO PETROLEUM EXPLORATION
Ao Qiaoqing
1986, 8(4): 386-396. doi: 10.11781/sysydz198604396
Abstract:
A novel method of petroleum geochemical exploration is introduced in this paper,i.e.the thermo-released analysis of AC carbonate in surface soils.AC carbonate referred here means the secondary carbonates which were derived from hydrocarbons and bought about erosion to the surface soils.Such an erosive carbonate is named as AC carbonate which occurs in the crystal lattices of surface soils with invariant content not effected external conditions.In view of its generative relation to hydrocarbons,positive abnormal geochemical haloes formed at surface could be used as indication of oil/gas pool in the underlying strata.The analytical method of AC is studied systematically in this paper.AC analytic device is designed and the analytical procedures of AC carbonates are established after various conditions have been tested.Furthermorer,the method is applied to petroleum exploration of various areas in combination with geochemical researches in order to test the feasibility of the method.
PYROLYSIS GAS CHROMATOGRAPHY OF KEROGEN
Ge Xiuli
1986, 8(4): 397-403. doi: 10.11781/sysydz198604397
Abstract:
This paper introduces a new method for the quantitative and qulitative determinations of the pyrolytic product of kerogen,using cold trap collector devices designed and made by ourselves and Varian model 3700 GC.This method is recently worked out with satisfaction and has been proved to be useful in the study of oil-generation.