1995 Vol. 1, No. 2

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PROGRESS OF GEOMECHANICS IN OIL AND GAS EXPLORATION IN TARIM BASIN
Kang Yuzhu, Kang Zhijiang
1995, 1(2): 1-10.
Abstract (142) PDF (659KB)(24)
Abstract:
A systematic study of the formation and development of the Tarim Basin and the associated tectonic systems was made by applying the principle and methods of geomechanics in petroleum geology.In the process the author intended to determine the oil-gas province oil-gas-enriched zones and hydrocarbon pools and make an assessment of them.As a result reservoirs in marine Paleozoic rocks were first found in the basin.
TECTONIC STRESS DRIVING AND MIGRATION OF GAS AND OIL IN NORTHERN TARIM BASIN
Shen Shumin, Feng Xiangyang, Liu Wenying
1995, 1(2): 11-20.
Abstract (160) PDF (706KB)(26)
Abstract:
The fault structures play an important role in controlling the formation, migration, accumulation and preservation of gas and oil in the northern Tarim Basin.The large repeatly active faults not only controlled the formation, development and evolution of large uplifts and depressions, but also acted as channel ways for vertical migration of oil and gas in different epochs.Small or second-order faults, and joints and cracks caused by faulting may improve the reservoir property, and are the major tectonic features that lead to the various structural trap of oil and gas in the region.
The authors think that the action of tectonic stress may create the most important conditions to drive the migration and accumulation of oil and gas.For the purpose to integrate the tectonic stress field responsible for the faulting with the material field in which migration of oil and gas takes place, a theoretical equation is established for the correlation of tectonic stress driving and fluid movement in the rocks.It represents the differential relation between tectonic stress, internal flow pressure and migrating potential.
Theoretical analysis and model calculation have been done for different oil-bearing structural types, their concentration conditions and locations in the known oil-fields in the northern Tarim Basin.The states of migration potentials have been simulated and calculated for a few typical sections in some major tectonic domains.The results obtained are compared with that of the known oil fields to find out the most likely areas for oil and gas exploration.
RESEARCH ON FAULT CLOSURE OF OIL
Sun Baoshan, Zhou Xingui, Shao Zhaogang
1995, 1(2): 21-27.
Abstract (158) PDF (473KB)(22)
Abstract:
This paper discusses methods for fault closure studies and its relation to oil-gas migration and accumulation.Qualitative researches focus on the mechanical properties of faults, disposition of rock types on the two sides of a fault surface for the closure fault geometry, fault activity, and its relation to oil-gas trap, as well as the relationship between faulting and tectonic stress field.The Semi-full quantitative research includes such methods as entry pressure measurement, reservoir description, fault closure grading, fault closuge closure grading and comprehensive fuzzy evaluation of fault closures, etc.
EXPERIMENTAL STUDY OF THE PRINAPLE AND REGA-LARITY GOVERNING TECTONIC STRESS CONTROL OF ORE DEPOSITS
Wang Chengjin, Wand Yiqiang
1995, 1(2): 28-34.
Abstract (159) PDF (442KB)(32)
Abstract:
In this peper, the authors discuss the ore-bound principle of strain energy and ore solution migration under a specific tectonic stress field that prevaiced during mi neralization. It is thought that strain energy and migration potential are controlled by the sum and difference of the principal stresses (σ1+σ2), (σ1-σ2).Photoelastic experiments of four typical structures under different boundary conditions indicate that the movement and concentration of ore-forming fluid is closely related to the tectonic stress field:the ore deposits are most likely to form where the strain energy gradient is steep or the fluid migration potential is low.Some examples of the typical structures are given.
EXPERIMENTAL DETERMINATION OF RHEOLOGICAL BEHAVIOUR OF HTGHLY VISCOUS MODEL MATERIALS
Zeng Zuoxun, Liu Lilin, Huang Dinghua, Xia Qinglin, Huang Xuqiao
1995, 1(2): 35-39.
Abstract (137) PDF (302KB)(19)
Abstract:
This paper introduces the principle and method for determing the rheological behaviour of highly viscous materials.Not only can the apparent shear strain rates, and non-newtonian shear strain rates of the materials be determined thereby but also the flow indexes, stress indexes and apparent viscosities.The rheological properties of a polymer model material "M503", a mixture of half-and-half of XM-50 (a sealing material) and talc powder by weight are subjected to determination.The test results show that the M503 is a pseudoplatic material and that its stress indexes vary from 1.15 to 3.33 and the apparent viscosities range between 4.69×107 and 0.99×107Pa·s when the non-newtonian shearstrain rates are between 7.52×105s-1 and 105.56×10-5s-1.
THE COLLATING AND STIPULATING OF “FENHE-WEIHE GRABEN” AND ITS SIGNIFICACE
Ning Chongzhi
1995, 1(2): 40-49.
Abstract (196) PDF (678KB)(23)
Abstract:
Data from different sources now available indicate that the "Fenhe-weihe graben" is actually composed of three separate enechelon arranged grabens, converging toward SW.The threee grabens had developed from the longitudinal tensiule faults on the crest of three antclines since Eocene and Pliocene times respectively, which are members of the eastern frontal arc of the Qilianshan-Lüliangshan-Helansh epsilon structural system.The distribution of earthquakes, occurrences of present-day surface cracks, geothermal anomalies, ground water resources as well as some endemic deseases are found all closely related to the three grabens and the associated horsts.
GEOLOGICAL STRUCTURES AND THEIR CONTROL OF SILVER-GOLD ORES IN HUJIAJIAN AREA, JIANGXI
Dong Faxian
1995, 1(2): 50-58.
Abstract (167) PDF (833KB)(22)
Abstract:
The Hujiajian silver-gold area is located in the southern part of the Wuyuan-Wannian fault-fold zone with the NE-trending compressoshear faults as the leading structural elements.The NE-trending faults have experienced three stages of evolution:in the early stage, they behaved as sinistral compressoshear faults, accompanied by plastic-brittle deformationl in the middle stage, they turned into tensoshear faults characterized by dominantly brittle deformation;in the stage, dextral compressoshear movement occurred with associated plastic-brittle deformation.It is therefore considered by the author that the tectonic activities in the area were governed by NE-treading Cathaysian stress field in the early stage and by NNE-trending Neocathaysian stress field in the late stage, and that the NE-trending faults were produced by the compounding of the NE-trending Taishan-type structures with the Cathaysian structures.
The NE-trending fault zones are the major ore-controlling structures.Silver-gold mineralization in chiefly controlled by the north subzoue of the Hujiajian-Xialing fault zone.There occur silver-gold and tungsten-antimony mineralization in the south subzone.Tungsten mineralization is confined to the Kutian-Tangjiabian fault zone.In addition, the distribution, shape, size, and content of the ore bodies as well as their mineralization pattern and type are closely related to the NE-trending compressoshear faults.There is some synchronism between structural evolution and mineralization.
TECHNICAL OF METHODOLOGY IN THE ORE FIELD TECTONICS
Wang Jianping
1995, 1(2): 59-65.
Abstract (122) PDF (531KB)(27)
Abstract:
The author describes the technical structure of the methodology in the Ore field Tectonics researches in terms of the four technical systems in modern sciences, and classifies them as:observation and detection technique, experimental technique, modeling technique, and information processing technique, Such a sequence of technology reference to the characters of the ten reseanrch methods is agreeable to the normal order in practical research work.In addition, a brief review of each of the techniques applied is made, andsome new applicable techniques introduced.
PALAR WANDER AND TECTOGENETIC MOVEMENT
Li Pu
1995, 1(2): 66-70.
Abstract (184) PDF (386KB)(23)
Abstract:
The large displacements of the Earth rotation axis with respect to the entire mantle on a geologic time-scale, called true polar wander (TPW), is detected by paleomagneticians, and its order of magnitude is about 1°/Ma.TPW is supported by mantle rheology. Apparent polar mantler (APW) of a continent minus TPW equals motions of this continent across the mantle.The author has studied Mesozoic crustal movements in North China with the TPW model, with the result that the variation of the latitude is greater than the variation of the azimuth relative to the mantle for North China Block since 200Ma.This is compatible with geologic evidence.It indicates the tectonic structures of North China had been definitely oriented.And the arc structures with the apex facing the south will have a different explanation for their existence with the TPW model than with the rotational deformation model.
APPLICATION OF PALEOMAGNETISM TO THE ANALYSIS OF BURIED STRUCTURES OF THE RONGDU GOLD DEPOSIT, ANHUI
Chen Bailin, Dong Faxian
1995, 1(2): 71-78.
Abstract (124) PDF (532KB)(15)
Abstract:
In this paper, the authors try to analyze the buried structures after determining the attitude of the sedimendary rocks and of the schistosity by measuring the remanent magnetization in core samples from the Rongdu gold deposit, Wuhe, Anhui.The results agree with the tectonic framework of the region.
CHARACTERISTICS OF TECTONIC MICRODOMAINS OF A WEAKLY CLEAVED QUARTZ SANDSTONE
Xu Xingwang, Ma Tianlin, Sun Liqian
1995, 1(2): 79-84.
Abstract (310) PDF (352KB)(25)
Abstract:
The difference between tectonic microdomains of a weakly cleaved quartz sandstone collected from the outer margin of a ductile shear zone shows that the development of cleavage in the rock depends on many factors, such asthe content and the size of sands, there will occur rotations and stretching of the sand grains during the formation of cleavage with a greater stretching and an earlier rotation for smaller grains.Grain-size sensitive deformation was the operative deformation mechanism.
A PRELIMINARY STUDY OF CLINOPYROXENE-GARNET TRANSFORMATION IN ECLOGITE FROM MENGZHONG, JIANGSU PROVINCE
Chen Xuanhua, Wang Xiaofeng, Chen Zhengle, Shu Guiming, Li Xiaofeng
1995, 1(2): 85-89.
Abstract (145) PDF (345KB)(20)
Abstract:
The genesis of the Jiangsu-Shandong ultrahigh-pressure eclogites has so far remained a puzzling problem.The preliminary study of the prograde metamorphism of the eclogites as represented by the eclogite-garnetite transformation in this paper, provides some initial evidence for their origin as a mantle transition zone (pressure up to 10 GPa).
MIDDLE PROTEROZOIC SEDIMENTARY SEPIOLITE DEPOSITS IN THE REGION OF BEIJING, TIANJING AND TANGSHAN
Zheng Daxing, Deng Jiwen, Qiu Yuanzheng, Zhang Ruifeng, Xu Gang, Wang Wenbin, Chen Baoli
1995, 1(2): 90-96.
Abstract (152) PDF (438KB)(19)
Abstract:
There is a wide distribution in the region of Beijing, Tianjing and Tangshan sedimentary sepiolite deposits which occur in the magnesium rich Carbonates of the Wumishan group of the middle Proterozic Jixian series.The geological structures of the region is simple with only weak magmatism.Investigations show abundant sepiolite deposits of occurrences in the region, and the sepiolite lager is thick and shallow.The mineral composition of the deposit is rather simple.In chemical composition, it is rich in magnesium and calcium and low in silicon.
The ore was tested to be easily and economically dressed, and with a high recovery and low cost, indicating a good prospect for exploitation.

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