Table of Content

25 June 1995, Volume 16 Issue 2

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A NEW SCHOOL OF THOUGHT IN SEQUENCE STRATIGRAPHIC STUDIES IN U.S.:HIGH-RESOLUTION SEQUENCE STRATIGRAPHY

Deng Hongwen

1995, 16(2):  89-97.  doi:10.11743/ogg19950201

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When high-resolution sequence stratigraphy represented by T. A. Cross Genetic Stratigraphy Group of Colorado School of Mines was introduced to the pubic,it immediately drew the attention of academic circles.The practical effect in application is remarkable.This marks a new development in sequence stratigraphy.The high-resolution sequence stratigraphy introduced in this paper focuses on more accurate prediction of sedimentary mineral deposit,especially concrete objective of oil and gas exploration.The high-resolution sequence stratigraphy takes the stratigraphic and sedimentary process-response dynamic principles,including the principles of stratigraphic base level,volumetric partition,factes differentiation and rule for chronostratigraphic cycle correlation as its theoretical bases.The practice of hydrocarbon exploration and development has proved that the high-resolution sequence stratigraphy has significant importance in factes analysis,3-D prediction of reservoir and the establishment of petrophysical model for fluid-flow numerical simulation.

ESTABLISHMENT OF GEOLOGICAL MODEL FOR LABYRINTH DIFFLUENCE CHANNEL SAND BODIES IN YOUSHASHAN OILFIELD, QINGHAI

Lin kexiang, Zhang Changmin, liu Huaibo, Lei Bianjun, Qu Pingyan, Ma Wenxiong, Let Bingzu, Tang Ruiying

1995, 16(2):  98-109.  doi:10.11743/ogg19950202

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The diffluence channel sand bodies of K₂-K_1-3 key horizones placed on the bottom of Pliocene lower Youshashan Formation in Youshashan Oilfield,Qinghai have developed into a deltaic labyrith reservoir frame. The frame prototype of outcropped sand bodies may be considered as the evidence in establishing underground prediction model.This means that data obtained from outcrops of the sand bodies including reservoir structure,the density and geometry(the ratio of width to thickness)of the sand bodies,regional paleocurrent direction,the ratio of total areas of prototype frame models of outcrops,the ratio of the area for sand bodies with different thickeness were used to establish the predictive transverse model, predictive plane model and permeabality model of the sand body frames.According to the prediction results.half of the reservoiring sand bodies have ever beed drilled yet.

HOLOSTRATIGRAPHY:A NEW CHALLENGE

Jiang Yanwen, Zhu Zhongde, Xiao Chuantao, Wu Zhiyong

1995, 16(2):  110-118.  doi:10.11743/ogg19950203

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It is believed that the traditional methods of stratigraphy are getting approach to their effective limits of resolution theoretically.Holostratigraphy,a newly emerged global cyclic stratigraphy,marks a new milestone for the development of stratgraphy.With its completely new thoughts.it extracts and develops in all espects all sorts of stratigraphic information contained in sedimentary records.The present paper briefly introduces the theoretical contents,study thoughts,actural substance and methods of the holostratigraphy.

ORDOVICIAN SUBMARINE FAN SYSTEMS IN WEST MARGIN OF ORDOS

Gao Zhenzhong, Luo Shunshe, He Youbin, Zhang Jisen

1995, 16(2):  119-125.  doi:10.11743/ogg19950204

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Various kinds of gravity flow sediments including terrigenous elastic gravity flow deposits and carbonate gravity flow deposits developed in the west margin of Ordos Basin from late Early to Middle Ordovician.The terrigenous elastic gravity flow deposits are more significant due to its great thickness and broad distribution extent.The gravity flow sediments could be classified into(1)low-density turbidity current deposit;(2)high-density turbidity current deposit;(3)matrix-rich debris flow deposit;(4)matrix-poor debris flow deposit.The first two types are well developed. Based on the study of sedimentary sequence,paleocurrent direction, distribution of turbidite in time and space, and major provenance,three submarine fans named Tongxin,Helanshan and Zhuozishan submarine fans have been identified with the total area of more than 43000km² and the thickness approximately 3000m.Among these submarine fans, Helanshan submarine fan is a high energy one,the other two are low energy ones. The submarine fan systems mentioned above possess good hydrocarbon prospects.

AN EFFICIENT APPROACH TO HYDROCARBON MIGRATION RESEARCHES

Chen Heli

1995, 16(2):  126-131.  doi:10.11743/ogg19950205

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Guided by the view of late-stage hydrocarbon migration and on the basis of deep geological studies,the comprehensive research system of hydrocarbon migratiorl is aimed to restore the evolution history of both fluid pressure and potential to assess dynamically the oil and gas potential of hydrocarbon-bearing basins.It has been proved by practice that the present system is indeed a very efficacious approach to hydrocarbon migration,and that it has evident precedence over static assessment.

CHRONOLOGY OF PALEOGENE VOLCANIC ROCKS IN JIANGHAN BASIN

Xu Lunxun, Yan Chunde, Yu Huilong, Wang Baoqing, Yu Fangquan, Wang Dianfu

1995, 16(2):  132-137.  doi:10.11743/ogg19950206

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The K-Ar isotopic ages of 23 Paleogene basalt specimens collected from Jianghan Basin were determined and isochrones were made according to different horizons.Isochron dating results are given as follows:the 4th member of Qianjiang Formation(E_q⁴)is 41.0 Ma;Jingsha Formation(Ej),45.5 Ma;Xingouzui Formation (Eχ),51.2 Ma;Shashi Formation (Es),62.4 Ma.The results are generally coincident with their stratigraphic times. Based on the results, the Paleogene geochronologic scale of the basin that is closely related to volanic activites has been made.

CHARACTERISTICS OF ORGANIC INCLUSIONS IN SOUTHERN SONGLIAO BASIN AND THEIR SIGNIFICANCE FOR PETROLEUM GEOLOGY

Chen Kongquan, Xu Yangang, Zhang Wenhuai, Xiao Haiyan, Tang Liming, Zhang Yuming

1995, 16(2):  138-147.  doi:10.11743/ogg19950207

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The measured monogenetic temperatures of organic inclusions in the fissures of mudstones in Shiwu Faulted Depression,Southern Songliao Basin Were 97.6℃,106℃, 122℃ and 168.8℃ respectively.This indicates that at least four periods of hydrocarbon expulsion took place.The reservoirs in the fault-depressde basin contain rich inclusions which are mainly in gas phase.But certain amount of oil inclusions could be found in Shiwu and Fulongquan Faulted Depressions.The monogenetic temperatures of the inclusions in the Shiwu Faulted Depression Were 70-80℃,90-110℃ and 120-140℃,which reflected three hydrocarbon migration and accumulation stages.The characteristics of the inclusions of Shiwu and Fulonguan Faulted Depressions Were similar. Liutiao Faulted Depression, hower, had fewer periods of hydrocarbon migration and accumulation, the monogenerous temperatures wre primarily 120-140℃.The abundance,type and distribution of organic inclusions of different depressions suggest that Shiwu Faulted Depression is active in hydrocarbon migration and accumulation and has good oil and gas prospects,lateral migration is its major migration manner;Fulouguan Fanulted Depression is secondary in hydrocarbon migration and accumulation,with vertical migration as its main manner;hydrocarbon migration and accumulation of other depressions are relatively weak but possess good gas exploration prospects.

DIAGENESIS OF CLASTIC ROCKS IN SHAHEJIE FORMATION, DONGPU DEPRESSION AND ITS RELATION TO ORGANIC MATTER EVOLUTION

Ji Youliang, Zhao Chenglin, Liu Menghui

1995, 16(2):  148-154.  doi:10.11743/ogg19950208

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Three high carbonate belts and four secondary pore belts developed vertically in the reservoir rocks of the Eogene Shahejie Formation in Dongpu Depression.CO₂ and organic acid generated from organic matter evolution dissolved feldspar grains and carbonate cements in shallow beds and formed the first secondary pore belt;the dissolution of feldspar grains in median depth resulted in the second and third secondary pore belts;the dissolution of carbonate cement in deep beds formed the fourth secondary pore belt.

APPLICATION OF RESERVOIR DATA SPECTRUM ANALYSIS IN DUANLIUBUO OILFIELD

Zhang Xing

1995, 16(2):  155-163.  doi:10.11743/ogg19950209

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A new technique-reservoir data spectrum analysis is proposed in this paper and it is used to quantitatively demonstrate the characteristics of reservoir micropore structures,establish static and dynamic reservoir models and standard micro factes charts,segment typical reservoir skeleton maps of different factes gones.It also describes the heterogeneities of varied flow units,the dynamic property of appearent pore structures.The reservoir properties and microfacies madel study thus quantitative demonstrated.

SEDIMENTS OF CREVASSE SPLAY IN WENCUNJIA

Cao Yaohua, Zhang Chunsheng, Liu Zhongbao, Lai Zhiyun

1995, 16(2):  164-169.  doi:10.11743/ogg19950210

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Intermittent flood crevasse is the main factor in the formation to Wencunjia crevasplayi adeep crevasse pond and the directional extansion of braided channels passing by hills and holows is the important geomorphic feature of the crevasse splay.The sediments of the splay are primarily graded-suspension transported.Sediments in water channels hawe distinct binary texture,but the binary texture of the sediments between the channels are not clear.This has resulted in fine sediments of the former than the later in the upper parts. The maim sedimentary structures include large scale of wash-filling bedding,trough cross bedding,Parallel bedding,sand ripple,homogeneous bedding.As for its grain size curves,type-Ⅰ is usually coarse and well-sorted, representing sediments deposted in lower parts of braided channels in the root and central parts of the splay;type-Ⅱ is relatively fine and better sorted, representing sediments deposited in the lower parts of the root and central sections of the splay between the channels,type-Ⅲ is fine but poor sorted.representing sediments in.splay margin. In consideration to the above mentioned,three sub factes such as deep pond,main body and margin subfacies have been subdivided.

SIMULATING EXPERIMENT OF SEDIMENTATION ON BAILIZHOU BEACH, YANGZI RIVER

Liu Zhongbao, Cao Yaohua, Zhang Chunsheng, Lai Zhiyun

1995, 16(2):  170-177.  doi:10.11743/ogg19950211

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Simulation result shows that the deltaic beach of Songzi River aggrades in the form of swallow tail and self-balance adjustiment in which master stream aggrades first and then branch streams. Flood period is the stage for the beach to develop.The beach roots in flood period, then it gets thinner in medium water level,and is exposed in low-water.River axis tends to the central line in high water level,it flexes in low water level,and this is supposed to be the controlling factor for the formation and evolution of Lujiahe beach.The lujiahe beach turns to be a wide point bar of concave bank in flood periods,and becomes a channel bar in medium and low water periods.Fenghuangtan and Jiangkouzhou Neaches are both dominated by cove pattern and the boundary conditions of the river channel.The Fenghuangtan beach would aggrade in flood periods while Jiangkouzhou would mainly be scoured.It means that the former would grow bigger and the later would decrease and subduce.

DEPOSITIONAL SIMULATION OF LOBATE SAND BODY IN QIBEI SAG

Zhang Chunsheng, Liu Zhongbao, Cao Yaohua, Lai Zhiyun, Gao Yuhua, Zhang Fumin

1995, 16(2):  178-183.  doi:10.11743/ogg19950212

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The result of simulation test shows that the shape of the sand body formed in the test changed from leaf shape of the first stage into lobate shape of the fourth stage.This is very similar to the lobate sand body of Sha-1 member in Qibei Sag.The first stage depositional body of the simulation test showed degradation tendency towards source area,the ratio of its thickness to its width reduced graduallys the second stage sand bed distributed extensively,and it connected with the first and the third beds, formed a unified reservoir;the fourth stage sand bed was an isolated lenticle surrounded by argillaceous sediments,its reservoiring property is relatively poor.

SEDIMENTARY CHARACTERISTICS OF HIGH-CURVED MEANDER POINT BAR IN SHATANZI AREA

Cao Yaohua, Zhang Chunsheng, Liu Zhongbao, Lai Zhiyun

1995, 16(2):  184-189.  doi:10.11743/ogg19950213

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Defferent parts of high-curved meander point bar in Shatanzi area have different grain size.type-Ⅰ represents the grain size of reeled crest distributed in upper and lower point bars;type-Ⅱ shows the grain size distributed in upper point bars;type-Ⅲ shows that of bars with trenches. The main sedimentary structure of the study area is cross-bedding, and the scale of it decreased in ascending order and it transforms into sand ripple or horizental bedding.This Kind of sediments is characterized by coarts grains in upper parts but fine grains in lower parts,and have binary sedimentary stucture. Within 13 kinds of lithofaces,6 lithofacies assemblages could be classified suchas sand-mud mutated, reeled crest,upper point bar,reeled trough,bar with trenches and lower point bar lithofacies assemblages.The mound landform that is composed of multi-reeled crests and troughs,and the bars with deep-cut trenches is well developed.

IMAGE PROCESSING TECHNOLOGY OF RESERVIOR STRUCTURES AND GEOLOGICAL PROFILES

Zhang Chunsheng, Cao Yaohua, Lai Zhiyun, Lin Jingfeng, Liu Zhongbao, Tao Deyuan, He Xiaohai, Li Shuping

1995, 16(2):  190-195.  doi:10.11743/ogg19950214

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The substance of the image processing technology of reservoir structure and geological profile is to make macroscopically and microscopically quantitative calculation and classification of reservoir porosity,throat,granularity according to the luminosity or colour of the sediments.This new technology,adopting computer image processing and pattern recognition system, could make sequence analysis of modern and ancient sediments,profiling,grading analysis,plotting probability curve and CM diagram,could make natural colour image of porosity distribution according to rock flake.

SEDIMENTARY CHARACTERISTICS OF BAYOU IN SHATANZI

Cao Yaohua, Zhang Chunsheng, Liu Zhongbao, Lai Zhiyun

1995, 16(2):  196-201.  doi:10.11743/ogg19950215

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Shatanzi bayou,formed of "Ω"-shape river cove, is an open sedimentary system.The bayou underwent concave bank collapse,covex bank cumulation and cut-cove bar forming stages.Water inlet and outlet are the main positionsof deposition.The deposit rate is 2-3m per year,but that of the apex of the cove is considerably slow.As for grain size curves,type-Ⅰ represents the grain size of the early stage sediments;type-Ⅱ represents the grain size of the early to middle stage sediments and type-Ⅲ shows that of middle to late sediments.Small or medium size of horizontal,parallel and wave bedding and mud cracks developed in the bayou.