Table of Content

25 September 1982, Volume 3 Issue 3

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DIAGENESIS IN RELATION TO EVOLUTION OF PORES IN SANDSTONE

Zhu Guohua

1982, 3(3):  195-203.  doi:10.11743/ogg19820301

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In Maling oilfield and its vicinity,the process of pore evolution in Yan-10 sandstones of Jurassic during diagenesis is discussed in this paper.The main conclusion proposed are as follows:1)The pore evolution is in fact a process of gradual substitution of secondary pores for the primary ones;2)The decrease of porosity in quartz arenites is mainly due to the precipitation of authigenic minerals in the sandstone pores during diagenesis;while the decrease of porosity in arenites with more flexible component is mainly caused by compaction during diagenesis;3)The secondary solution pore mainly developed after its diagenetic stage by dissolution and kaolinization in arenite which is abundant in feldspar.This process is likely to be related to the decarboxylation of organic matter in interbedded coal seams and carbonaceous shales by thermalizatin;4)The clastic constituents of sandstone controlled by source materal distinctly affect the development of pores.Therefore,the primary and secondary pores in sandstones favourable can be predicted on the basis of finding out the source material of sediments;5)Diagenesis obviously affects on the texture and the uniformity of pores in sandstones.

THE EARLIER LATE TRIASSIC SEQUENCE AND ITS SEDIMENTARY ENVIRONMENT IN WESTERN SICHUAN BASIN

Deng Kangling, He Li, Qin Dayou, He Zhiguo

1982, 3(3):  204-210.  doi:10.11743/ogg19820302

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The Ma'antang formation was found in Jiangyou County,Sichuan province as early as 1973.Based on its fossils such as Ammonite,Conodont,Bivalvia,Foraminifera and Sporo-pollen collected and studied in recent years,the writers refer it to the earlier Late Triassic,that is Carnian stage.Its lithofacies and fossilassemblages are described here in detail.This formation is distributed over Jiangyou,Mianzhu,Shifang,Emei,and Yanting regions.At the beginning of this stage,the transgression of Tethys sea came from Aba and Garze areas,and reached the western part of the basin.A series of carbonate rocks deposited there.At the middle and later stages,the sea extended towards the south-east and clastics took place in the area of Anyue.In this way,the western part of Sichuan basin comprised the eastern shelf of Aba-Garze sea.

THE FUNDAMENTAL SEDIMENTARY FACIES OF MODERN CORAL REEFS IN HAINAN AND XISHA ISLANDS

Wang Guozhong, Lu Bingquan, Quan Songqing

1982, 3(3):  211-222.  doi:10.11743/ogg19820303

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On the basis of investigation of modern coral reefs of Hainan and Xisha Islands of China,fundamental sedimentary facies of these regions have been identified,and the diagnostic criteria for the discrimination of various reef facies are proposed.From the fore- to the back-reefs,the sedimentary facies zones can be sbdivided as follows:the epeiric sea sand-mud facies,the fore-reef colluvial facies,the protogenous reef facies,the marginal reef conglomeratic facies,the reef flat sandy-conglomeratic facies,the sand cay(barrier)conglomerate-sandy facies and the lagoonal sand-mud facies.The differences between various types of coral reefs are in relation with the associations and the distribution of these sedimentary facies.It has been realized that submarine relief is the main factor in determining the patterns and sizes of the sedimentary facies zones.The sediments of coral reefs in the area of the Pacific-Indian Oceans are predominatly composed of the algal debris,and yet sediments of coral reefs in the South China Sea are predominatly composed of Petraiidae.

A PROGNOSTIC SYSTEM FOR OIL AND GAS POTENTIAL

Cheng Xuefu, Ding Taimu

1982, 3(3):  223-230.  doi:10.11743/ogg19820304

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Prognostication of oil and gas potential serves as one of the bases in formulating an energy policy,planning the economic construction of a country,and drawing up a plan for exploration.In this paper,the relationship of interaction and alternating development between prognostication and exploration is analysed.The necessity of developing a prognostic system of oil and gas potential is elucidated in the light of the characteristics,the methods,and the reliability of the prognostication.As an overall object,the research on the prognostication of oil and gas potential is essentially a synthetical course of the knowledges of multiple disciplines,in which the synthestic methodology of interdisciplinary nature derived from"system theory", "information theory"and "cybernetics"et al.should be used,so that it can be characterised by"dynamical"and"trial and error"analysis.Based on system engineering,a three-dimensional structure of object-information-method and its dynamical scheme are proposed,together with a systematic developing approach and the optimization of the system using a changeable matrix.The purpose of this article is to seek for an optimal way to prognosticate oil and gas potential throughout China.

A DISCUSSION OF THE RELATIONSHIP BETWEEN FUSULINID ECOLOGY AND HYDRODYNAMIC ENVIRONMENT——by way of example of Later Chihsia Stage,Early Permian,Guizhou Province

Wang Liting, Dong Wenlan, Ye Nianzeng, Chen wenyi

1982, 3(3):  231-239.  doi:10.11743/ogg19820305

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Through drawing the lithofacies-palaeographic map of Later Chihsia Stage,Early Permian,Guizhou province,it has been found that not only the fusulinids possessed the horizontal zonation conformed to the distribution of palaeographic environment but also their outerform and internal structure adapted to different energetic environment.In this study,a great number of regional geological surveying information has been used,including 109 sections,529 samples and the statistical data of 17 fusulinid genera.In general,the spherical,subspherical fusulinids with simple internal structure were widely distributed in and adapted the quite tranquil environment.Thus,they mostly accumulated in the low energetic subrestricted platform.Contrarily,the inflated fusiform and fusiform fusulinids were widely distributed in open platform facies of west and central Guizhou.A number of elongate fusiform fusulinids with complicated structure predominantly lived in the high energetic zone of biobank of Ceheng-Ziyun District.According to the point of view of hydrodynamics,the writers have studied the relationship between the fusulinid ecology and palaeoenvironment,and have emphasized the important significance of drawing the lithofacies-palaeographic map through the statistics of actual information and theoretical analysis.

HYDROGEN AND OXYGEN ISOTOPIC COMPOSITION AND GENESIS OF THE GROUND WATER IN JIZHONG DEPRESSION

Sun Shan, Xie Jiasheng, Li Guiru, Qiu Chunyi

1982, 3(3):  240-249.  doi:10.11743/ogg19820306

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Achievements in determination of hydrogen and oxygen isotopic composition from stratum and oil field waters of various ages are used in discussing the origen of reginal ground waters and their regim of motion.Variation of these isotopes in Jizhong depression have their regularity both in horizontal and vertical directions.Three aquifers in this paper are discussed.Most of δD and δO¹⁸ values of Q-N aquifer system are plotted on δD-δO¹⁸ correlation curve of standard meteoric waters,with only few points shift not far to the right side.In samples,the ion contents,total solids,temperature and δD values are clearly correlated to each other.It is suggested by the author that this system is an admixture of meteoric waters with stratum ones.In E aquifer system,δD and δO¹⁸ values fall between curves of meteoric waters and SMOW.All values are concentrated in a highly restricted area and are higher than that of Q-N aquifer system.It proves that this kind of stratum waters is an admixture of ancient atmospheric waters with syngenetic depositional water.The Pz-Za aquifer system in "buried hill"traps has relatively stagnant hydrodynamic condition and is in dynamic equilibrium state with lower Tertiary stratum waters,differing from openly circulating ground waters in underlying"buried hill"system.Every water system is characterized by its own isotopic composition and hydrochemical index.This study provides some evidences for oil formation,migration,accumulation and preservation in region under consideration.

A STUDY ON THE STRUCTURES OF BIOGENETIC SUBSTANCE IN DISSEMINATED HYDROCARBONS BY GAS CHROMATOGRAMS

Huang Difan, Li Jinchao

1982, 3(3):  250-258.  doi:10.11743/ogg19820307

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The analytic principles and prerequisites for structure of the biogenetic substance of dissemninated hydrocarbones in source rocks by gas chromatograms are discussed here by the authors,and these hydrocarbones have been classified into four peak groups derived from fatty acids,biological waxes,pigments and other biological lipids.In addition,elucidations of some characters of their evolution are put forward in conjunction with computing an example.

THE APPLICATION OF SEISMIC STRATIGRAPHY IN BIYANG DEPRESSION

Yang Zicai

1982, 3(3):  259-269.  doi:10.11743/ogg19820308

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Biyang depression is typical with good source rocks and reservoir sands in Paleogene.The first attempt was made to divide seismic sequences,analyse seismic facies and calculate interval velocities of the main reservoir rocks in this area.As a result,seismic sequences are reestablished,some new views of structure is proposed on the basis of the theory and the method of seismic stratigraphy.Based on synthesis of the information of amplitude,frequency,continuity,abundance and reflecting structure,the essential reservoir bed（E₂h₂³）of this depression is divided into eight segments of seismic facies and then transformed into lithological zones.It has been found that the lower velocity abnormal belts varied horizontally in interval velocities are coincident with the known oil-bearing areas,while the higher velocity abnormal belts reflect the increasing content of dolomitic composition in sedimentary rocks.Finally,the assessment of oil prospects of unknown areas has been proposed according to various data available.

DISTRIBUTION CHARACTERISTICS OF GAS POOLS IN CHINA

Dai Jinxing

1982, 3(3):  270-276.  doi:10.11743/ogg19820309

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This paper expounds some characteristics of China's gas pools from stratigraphic sequences,lithologic characters of reservoirs,and types of gas pools and basins.They are given as follows.1.The pool-types discovered in China are mostly anticlines and then fault blocks and lithological variations.In addition,there are a little of synclines,reefs and weathered crusts.2.The proved gas reserves in China are 30.7% in Triasic,21.7% in Tertiary,20.2% in Permian,and 16.2% in Sinian system.3.The proved gas reserves occur mainly in intracratonic polycyclic basins,intracratonic rift basins,back-arc basins and intermountainous basins.The first two are make up about 93% of the total reserves.4.67.9% and 32.1% of proved gas reserves are contained in carbonates and clasolites respectively.

DISCUSSION ON CRUSTAL MOVEMENTS IN NORTHERN JIANGSU ON THE BASIS OF SPORO-POLLEN

Zhou Shanfu

1982, 3(3):  277-281.  doi:10.11743/ogg19820310

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Northern Jiangsu,a block-fanlting basin with Cenc-Mesczcic continental deposits,is chequered with depressions and uplifts.In studying the sporo-pollen in these sequences,the writer found out that the high frequency zones of disaccate pollen basically coincide with Yizheng,Wubao and Sanduo movements which took place in this area.The disaccate pollen,consisting of Pinaceae and Podocarpaceae,including Abies,Picea,Cedrus,Pinus,Tsuga,Larix,Podocarpus and Dacrydium,etc.are now nearly all growing on hills and mountains.Therefore,its high frequency zones in geological time reflect exactly the ancient crustal movements which lead to hill-and mountain-forming in areas of uplifts.A numerical synthetical curve diagram of the sporo-pollen assemblages of a drill hole has been drawn up(Fig.1-5) to show the relations between the occurence of the sporo-pollen and crustal movements.

PRELIMINARY APPLICATION OF SATELLITE IMAGES TO PETROLEUM EXPLORATION IN SHIZHU SYNCLINORIUM

Zhou Xiangyiang

1982, 3(3):  282-286.  doi:10.11743/ogg19820311

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In this paper,basement and local structures of Shizhu synclinorium in east Sichuan are studied by means of satellite remote sensing images in combination with seismic,borehole and surface geologic data.As a result,the Huangshuiba and Mixi structures,and a series of subcircular images(possible local structure)are discovered.After having discussed the mechanism of their formation and relationship between these structures and sedimentary facies,such as bioherms,analysed the oil generation,migration,accumulation and preservation in the area,some assumptions are proposed by the writer for further oil and gas prospecting.

SUN JIANCHU—AN OUTSTANDING GEOLOGIST IN PETROLEUM GEOLOGY

wang Yangzi, Huang Xitao, An Yankai

1982, 3(3):  287-289.  doi:10.11743/ogg19820312

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Mr Sun Jianchu(1897—1952),the founder of Yumen oil field,was an outstanding geologist of China.It is the thirtieth anniversary of his death this year.Mr Sun was born in Puyang,Henan Province.He graduated from Shanxi University in 1927,and for long he stuck to field survey over more than 10 provinces,searching for mineral resources such as iron,coal,crude oil,etc.for native country.From 1937,he began his work in Gansu and Qinghai Provinces.After a large amount of hard work on petroleum geology,he discovered the famous Laojunmiao oil field and held the field's petroleum prospecting and exploration with brilliant achievements.Mr Sun was appointed successively the chief geologist of the Petroleum Buerau of Gansu,the directer of Exploration Department of Petroleum Administration,Ministry of Fuel Industry,as well as a specialized commissioner in Academy of China.He was an active leader and director in charge of petroleum exploration in western China and throughout the country and made distinguished contribution.As a pioneer,Mr Sun was highly respected by petroleum geologists all over the country.This article was written in memory of him.