1993 Vol. 15, No. 2

Display Method:
A MODELLING ON THE FORMATION OF NATURAL GAS POOLS IN THE WEST SICHUAN DEPRESSION OF THE SICHUAN BASIN
Zheng Zhaoyang, Guo Dixiao, Luo Qiuxia
1993, 15(2): 115-127. doi: 10.11781/sysydz199302115
Abstract:
Located in the west of Sichuan basin,the western Sichuan depression is a suite of sedimentary sequences developed in the Karnian of late Triassic,representing the evolutions of the passive continental margin(the basin under the Xujiahe Formation),intraconti-nental foredeep basin(the basin above the Xujiahe Formation)and intracontinental depression(J~K).Therefore,its formation and development are related to the closure of the Tethyan oceanic basin.The authors modelled on the varying patterns of the depression during its geological history,hence to clarify the formation,migration,accumulation and dispersion of the natural gas in the western Sichuan Depression.
SEDIMENTARY FEATURES AND HYDROCARBON POTENTIAL IN THE TRIASSIC SYSTEM OF THE TARIM BASIN
Tang Kaijiang
1993, 15(2): 128-137. doi: 10.11781/sysydz199302128
Abstract(1581) PDF-CN(331)
Abstract:
The Triassic system of the Tarim Basin mainly consists of the coal-bearing clastic rocks of fluvial-lacustrine facies,intercalated with pan-marine carbonates,sands and mudstones;the thickness of the system ranges 500-1900m,and the distributing area reaches to about 30×104km2.In the system the source rocks mainly developed in deep-shallow lake subfacies,delta facies and pan-marine facies,lithologically it is characterized by dark mud,shales,carbonaceous mudstones intercalated with grey carbonate rocks,coals and oil shales.The accumulated thickness is up to 200-800m.The Majiar and Tangguzibasi depressions in the basin are the two major source rock areas totalling to about 13 ×104km2.The organics are predominately attributed to types ⅡB~Ⅱ,then to types Ⅱ~Ⅰ,with the R°values ranging 0.6~1.2%,therefore,they have a good hydrocarbon potential.In recent years,the several significant break-throughs of oil/gas exloration have been made in the Triassic system of the Northeast Tarim Basin,suggesting there is an extensive prospect for the petroleum exploration in the Triassic system of the basin.
ON THE OVERTHRUST ZONE IN THE NORTH MARGIN OF THE LAJISHAN, THE SOUTHERN QILIAN MOUNTAINS
Yang Zhongxuan
1993, 15(2): 138-145. doi: 10.11781/sysydz199302138
Abstract:
The overthrust structural zone on the north margin of the Lajishan Mts.,the southern Qilian Mts.,formed after Miocene,and all the faults like listric shape and converged toward a united detachment sole in the deep crust.It is considered that the discovery of such a structure would expand the oil/gas prospective area in the Minhe Basin
ON THE STIPULATION OF THE QINGBAIKOU SYSTEM IN THE SOUTH CHINA
Shan Xianglin
1993, 15(2): 146-159. doi: 10.11781/sysydz199302146
Abstract:
There has been a long debate upon the important question whether the Qingbaikou System developed in South China and how its division and correlation can be made.In accordance with the principles of tectonomagmatic cycles,the Precambrian Systems mainly in Yangtze region are divided,studied and analysed in the paper,on the basis of the regional unconformity,sedimentary formation and correlation combined with the data of iso-topic age and micropaleobotany assemblage.The author proposes a scheme for the division and correlation of the Qingbaikou System in South China.Its bottom boundary is an unconformity resulted from the Jinning Movement,and its top boundary is at the bottom boundary of Liantuo Formation or the bottom boundary of equivalent horizons to Liahtuo Formation,with the isotopic ages being 100±Ma and 80±Ma,respectively.The strati-graphic characteristics of the system are discussed for each subarea.
THE RELATIONSHIP BETWEEN THE CHARACTERISTICS OF THE STRUCTURE AND MICROSTRUCTURE OF THE STRUCTURAL ZONES AND THE OIL/GAS EVOLUTION IN ANHUI AND ZHEJIANG PROVINCES, THE LOWER YANGTZE AREA
Li Jiabiao
1993, 15(2): 160-167. doi: 10.11781/sysydz199302160
Abstract:
In this paper,it is proposed that the structures in the Lower Yangtze Area of Anhui and Zhejiang provinces can be divided into three structural zones from shallow to deep as the flexural,breakage-flow cleavage and fliated flow zones with the deformation temperatures of 350℃,420℃ and 500℃ respectively,based on the structural observations and microscopic analysis,as well as the measurements on deformation temperatures.All the structural zones developed during the period of intracontinental orogenesis from the In-dosinian to Early Yanshanian and they have obvious controls over the maturities of the Paleozoic organic materials in the area depending on regional geochemical studies and the oil/ gas distribution.It is,however,suggested that the established relationship between the structural zones and the evolution stages of the Paleozoic organic materials show the fliated flow zone corresponding to the post dry gas stage,the breakage flow cleavage to over-matue stage and the flexure to mature or high level of mature stage respectively for the oil/gas evolution in the area.
THE SUPERPRESSURE MUD SEAMS IN THE SOUTHERN MARGIN OF THE JUNGGAR BASIN AND THEIR SIGNIFICANCE IN STRUCTURAL GEOLOGY
Kuang Jun
1993, 15(2): 168-173. doi: 10.11781/sysydz199302168
Abstract:
The superpressure mud seams developed in the mudstone layers of the Xiaoquangou Formation of the U.Triassic and the Jianghe Formation of the L.Jurassic in the Tuositai Area of the west end on the southern margin of the Junggar Basin and those in the Anjihaihe Formation on the south margin.The superpressure mud seams in the first two formations occurred during the late stages under the major tectonic uplifts and the excellent self-closed conditions while those in the Anjihaihe Formation formed under the disequilibrium between the compaction-discharge flows of the mud seams and the hydrocarbon generation.However,the superpressure mud seams could be the cause both for the well-development of extrusion structures and the excellent sliding sheet for the gravity decollement structures.
THE DISCOVERY OF COMPACTED LIMESTONE MICROPOROUS RESERVOIR IN THE UPPER QIULITAGE GROUP, THE NORTHERN TARIN BASIN AND ITS SIGNIFICANCE
Ye Desheng
1993, 15(2): 174-184. doi: 10.11781/sysydz199302174
Abstract:
The compacted minimicritic limestones of the Upper Qiulitage Group( Lower Ordovician)are one of the prospecting targets in the north Tarim Basin.The type of the reservoir pores is dominated by micropores,attributed to an unconventional type of suture-micropore reservoir.The micropores formed preponderantly under corrosion,particularly the deep corrosion.It is a compacted limestone reservoir with micropores discovered recently in the country,which would be significant for it provides scientific basis for petroleum exploration,and renew the types of carbonate rock reservoir in China.Meanwhile it makes the studies available on the origin and evolution of micropores.
THE APPLICATION OF GRAIN SIZE ANALYSIS TO THE CLASSIFICATION OF FAN-DELTAS
Sheng Heyi
1993, 15(2): 185-191. doi: 10.11781/sysydz199302185
Abstract:
In small fault lacustrine basins,the sedimentary fan-deltas are widely spread with a long evolution history and various features.The Paleogene lacustrine basin in the Liaohe Fault could be taken as one of the examples.In this paper,the author quantitatively classified 12 sedimentary fan-deltas of the Liaohe fault basin on the basis of the characteristics of fault development,facies patterns,sedimentary hydrodynamics and lithofacies analysis with the application of the classification and statistics on the probability curves of grain size analysis and six sedimentary types have been divided.Consequently,the classification is not only coincided with the regional structures of the basin and the objective time-space law of the sedimentation,but also reveals the regularities between the nonhomogeneous characteristic parameters of the reservoir beds in the six sedimentary types and those between the features of mining points.Therefore,the established systematic classification model can be regarded as the correlation maker and the prediction model in the reservoir beds of six sedimentary types for their oil/gas exploration and development in early stages.
SILICEOUS CEMENTATION OF SANDSTONE RESERVOIRS IN No.1 SECTION OF THE DAINAN FR. OF THE GAOYOU DEPRESSION AND ITS INFLUENCE OVER THE RESERVOIR PROPERTIES
Huang Shanbing
1993, 15(2): 192-200. doi: 10.11781/sysydz199302192
Abstract:
Based on the microscopic-analysis on casting thin sections,SEM,X-ray diffraction and cathodoluminescence,the author believes that the silicic cementation is the dominant cause for the reduction of a large amount of pores in Ed1 reservoir and the poor effects from acidization procedures for production improveme.Therefore,it is proposed that hydrofluoric acidizing process should be adopted on the reservoirs with well-developed silicic cementation when the acidization procedure are applied to oil/gas development,which does show good effects.
THE ROLE OF ORGANIC FACIES IN EVALUATION OF SOURCE ROCKS AND OIL/GAS-A CASE STUDY IN THE PERMIAN SYSTEM OF LOWER YANGTZE
Li Huadong, Wang Rongfu, Wu Xinyi, Lu Jiayan, Zhou Leifeng
1993, 15(2): 201-212. doi: 10.11781/sysydz199302201
Abstract:
On the basis of the features of sedimentary facies,material source,biological assemblages,geochemical facies,the abundance and types of organisms,hydrocarbon potential,etc.,the paper makes a comprehensive study on the organic facies of major oil-gas source rocks in the Permian system of the Lower Yangtze Region.Meanwhile the concept of organic facies is proposed.It is suggested that the organic facies can be clarified into subfa-cies of highly oil-prone phase(A),oil-prone phase(B1),gas-prone phase by oil cracking(B2),oil-gas mixing phase(B-C),oil/gas barren phase(D)respectively in accordance with the classification of organic facies and their indices.
AN ENRICHMENT TECHNIQUE OF FREE HYDROCARBONS AND ITS APPLICATION IN PETROLEUM GEOCHEMICAL EXPLORATION
Wu Sihang, Wei Meihua
1993, 15(2): 213-219. doi: 10.11781/sysydz199302213
Abstract:
Based on the principles of thermodynamics and dynamics,the authors designed and developed a new device for the concentration and enrichment of hydrocarbon gases.So that it can increase the concentration of free hydrocarbons in the air by several orders of magnitude,which certainly opens up the way to further the analysis of trace hydrocarbon in petroleum geochemical exploration.It can not only improve the analysis of trace hydrocar-bon(C1-C7)in air samples from the surface gas bearing beds and the soil above the oil/ gas pools,but also be applied to analysing the tank-top gas and water-soluble gas as well as to petroleum chemical exploration in marine area.
APPROACH THE INFLUENTIAL FACTOR △C AND ITS MODIFICATION
Li Qingjun
1993, 15(2): 220-224. doi: 10.11781/sysydz199302220
Abstract:
With △C theory,it is believed that a pyrolysis will take place only in the altered carbonate of hydrocarbon generation under the temperature range of 500~600℃.However,through the experiments,the author concludes that much pyrolyses will occur in the secondary carbonates of other origins at the temperatures of 500~600℃.It means that these secondary noncrystalline carbonates( including △C)are the major pyrolytic products within the temperature range.In view of this,the author modifies their measurements based on the functional relationships between the carbonates.