1992 Vol. 14, No. 2

Display Method:
ON THE GLIDING-DECOLLEMENT STRUCTURES DEVELOPED DURING INDOSINIAN-EARLY YANSHANIAN EPOCH IN THE NINGZHEN MOUNTAIN RANGE
Liu Shaofeng, Zhuang Peiren, Xu Chengyan
1992, 14(2): 109-115. doi: 10.11781/sysydz199202109
Abstract:
The gliding-decollement systems at multiple levels took place within the Mesozoic-Palaeozoic marine sedimentary sequences. During Indosinian-Early Yanshan,due to first regional gravitation and then pushing-compression occurred in the area,the continuous and progressive decollement-deformation developed along different horizons within the sedimentary sequences,bringing about gliding decollement structures. The main patterns of the structure are of box-foldings,decollement along the horizons,and folding-overthrustings. In this paper,it is proposed that there are two models for the gliding decollement structures,i, e. decollement with overthrusting during Indosinian epoch and over-thrusting with d. ecollement in Early Yanshan.
ORGANIC GEOCHEMISTRY OF ISOMETAMORPHIC COAL-CHARACTERISTICS OF NUCLEAR MAGNETIC RESONANCE (NMR)
Zhao Shiqing, Wang Feiyu
1992, 14(2): 116-124. doi: 10.11781/sysydz199202116
Abstract:
In the paper, the NMR characteristics of vitrinites and their chloroform soluble matters from the two coal facies during the high volatile stage of bituminious coal (Rmaxo≈0.64~0.74%)are approached by the techniques of CP/MAS-13C-NMR and 1H-NMR. Moreover, with the basis of element analysis,separation of extracts and coal petrological characteristics,the authors have studied the vitrinite textures of the two coal facies.
RESERVOIR PROPERTY OF THE SINIAN-ORDOVICIAN DOLOMITES IN THE NORTHEAST TARIM BASIN
Ye Desheng
1992, 14(2): 125-134. doi: 10.11781/sysydz199202125
Abstract:
The principal reservoir rocks in the northeastern Tarim Basin are composed of the Sinian-Or dovician dolomites,and the high productive oil reservoirs met by well-known drilling well Shacan-2 are attributed to the Ordovician dolomite system. In this paper, their reservoir properties and the controlling factors are approached. Furthermore, the evaluation of the individual layers of the reservoir and the prediction of favourable regions for the prospecting plays of oil/gas fields have been made in this paper.
THE SIGNIFICANCE OF DEPOSITIONAL ENVIRONMENT AND TECTONIC SETTING OF THE XIKOU FORMATION (T1x) IN THE WESTERN FUJIAN
Zhou Zuyi
1992, 14(2): 135-141. doi: 10.11781/sysydz199202135
Abstract:
The Xikou Formation (T1x) in the western Fujian is a set of flysch deposits attributed to the basement of a foreland basin and is a rapid sedimentation in deep-marine and turbulent environments of active continental margin. The flysch sequences constitutes a complete series of sedimentary sequences of the foreland basin. The development of the sequences would be closely related with rather mild orogenesis during the early Mesozoic time along the coastal area of the southeast China.
ON THE PETROLEUM PROSPECTS IN THE NORTHERN TIBET
Mu Qing
1992, 14(2): 142-151. doi: 10.11781/sysydz199202142
Abstract:
It is suggested that there are certain prospects in the northern Tibet,and detailed studies should be carried on the Lunpola and Qiangtang basins in the region. The Lunpola Basin is a Cenozoic faulted basin, with the thickness of about 5000m Tertiary non-marine sediments, hundreds of meters of source rocks and a geothermal gradient of 4.6~6.6℃/100m. Up to date,31 anticlinal structure shave already been discovered, among which the largest trap can reach as much as 40.2km2. However,the Qiangtang Basin is a Mesozoic petroliferous basin with a total area of 19.5×10.4km2. The marine Mesozoic sedimentary sequences are of 14000m thick,of which the thickness of the Jurassic system is up to 7800m. In the source rocks, the organic carbon is about 0.17-2.14%,white its Ro ranges 1.12~0.65%,being attributed to type Ⅱ kerogen.
AN ATTEMPT TO CALCULATE THE PRIMARY THICKNESS AND THE AMOUNT OF DIFFERENTIAL COMPACTION IN A FORMATION WITH AN APPLICATION OF COMPACTION SIMULATIONS
Guan Zhengliang
1992, 14(2): 152-158. doi: 10.11781/sysydz199202152
Abstract:
A new method and its principles are introduced to calculate the primary thickness and amount of differential compaction in a formation, through practical studies of compacting simulations. Furthermore, the advantages and defects of the method are also discussed in this paper.
A PRELIMINARY APPROACH TO THE CHARACTERISTICS OF GRAVITY AND MAGNETIC FIELDS AND THE UPPER CRUSTAL LAYERED STRUCTURES IN THE AREA OF THE SOUTH JIANGSU, THE LOWER YANGTZE PARAPLATFORM
Jiang Yongji
1992, 14(2): 159-169. doi: 10.11781/sysydz199202159
Abstract:
Based on the data and information derived from gravity and magnetic investigations in the South Jiangsu with computer processings and combined with relative geological studies, it is suggest ed that the characteristics of the gravity and magnetic fields and the upper crustal layered structures show as follows: 1. A series of interval positive and negative abnormal zones of gravity and magnetic fields, ab normal gravity and magnetic gradients distributed along various trends,and abrupt changing and contortion of axial abnormalies have suggested that a number of NE, NNE composite anticline and syn cline-folding belts and NE, near-NW, NNE and NW four groups of structures formed in the various periods have developed in the area of the South Jiangsu. 2. the distribution of gravity and magnetic field intensity and their physical characteristics re veal that the overthrust in various trends and regional decollements developed in different levels and depths accompanied with foldings and fault structures in the area. 3. The upper crust of the area is characterized by three layered structures i. e. the layer of basement structures, the layer of petroliferous structures and the layer of draping structures.
AN ANALYSING METHOD OF ISOALKANES AND CYCLOALKANES AND ITS GEOCHEMICAL SIGNIFICANCE
Xu Lian, Liang Shu
1992, 14(2): 170-180. doi: 10.11781/sysydz199202170
Abstract:
An analysing method of trace isoalkanes and cycloalkanes in geosamples are introduced in this paper. Its process includes a separation of trace isoalkanes and cycloalkanes from the total alkane fraction, and henceafter a separate GC analysis. The method, being simple, capable of ultra micro-analysis and high efficiency of separation, provides new analytical techniques for micro-hydra carbon samples, particularly those sampled from marine carbonate rocks with low organic content and high maturity in the area of the southern China.
A PRELIMINARY STUDY ON HYDROCARBON GENERATION FROM SECONDARY EVOLUTION OF THE CARBONIFEROUS-PERMIAN COAL SERIES IN NIQIUJI FAULT-DEPRESSION
Han Yunsheng
1992, 14(2): 181-187. doi: 10.11781/sysydz1992021781
Abstract:
Using parameters of bitumen A, hydrocarbon content, hydrogen/carbon, atomic ratio, macer als and vitrinitc reflectance, a systematic correlation on the parameters from the wells Nan 6 and Nan 11 has been made. The two wells are located within the same faulted depression and have expe rienced similiar sedimentation but different in the thickness of the overlying sequences. It is revealed that a secondary evolution of hydrocarbon generation did occur in the Carboniferous -Permian coal series within the area. Preliminarily the depth for the hydrocarbon generation threshold is defined at 3400m, and the initial expulsion at 4000m deep. The author believes that what mentioned above can provide scientific basis for the explorations of gas (oil) pools derived from the secondary evolu tion of coal series.
DISTRIBUTION AND GAS-BEARING CHARACTERISTICS OF THE CENOZOIC IGNEOUS ROCKS IN THE JIZHONG DEPRESSION
Liu Qianzhi
1992, 14(2): 188-194. doi: 10.11781/sysydz199202188
Abstract:
In the Jizhong Depression, the Cenozoic igneous rocks, distributing within the Eogene strata, trend to be younger in age but increase in thickness, and in area from the south toward the north. The maximum distributing area occurs in the Langgu Depression, approximate to 1000km2, with a thickness exceeding 500m, dominated by diabases. The thermal alteration of the intrusions and erup tions improves the conditions of oil/gas generation, and provides favourable conditions for large amount of oil and gas accumulations. The reservoirs relating to igneous rocks consist of basalts, diabases, tuffs and spotted slates, mainly characteristic of secondary dissoluted pores and fissures, among which the spotted slates is the best one in property. As a result, three types of traps would be developed, i. e. updipping thin-out, lenticle and structure-lithology traps. The oil/gas pools discovered up to date are principally of structural lithological traps.
ON MARINE TO NON-MARINE FACIES TRANSFORMATION OF THE PERMIAN SEDIMENTATION IN THE CHAOHU LAKE, ANHUI PROVINCE, WITH THE APPLICATION OF MnO/TiO2 INDEX
Wang Ziyu
1992, 14(2): 195-199. doi: 10.11781/sysydz199202195
Abstract:
Based on the data of systematic chemical analyses, the transformation between the non-marine facies in the Permian system of the Chaohu Lake, Anhui Province are discussed paper, with the application of MnO/TiO2 ratio. The results obtained are basically consistent those from C/S ratio, 13C,as well as the synthetic analyses of palaeontology and the sedimentary vironmcnt of petrostratigraphy. Therefore, it is in evidence that MnO/TiO2 can be regarded as fective geochemical index for defining the depositional cnvironment of marine sediments and is available for studying on the changes between marine and non-marine facies.
NATURAL GAS OF THE MANTLE ORIGIN IN WUDALIANCHI
Dai Jinxing, Wen Hengfan, Song Yan
1992, 14(2): 200-203. doi: 10.11781/sysydz199202200
Abstract:
The geochemical characteristics and origin of the natural gas in the area of Wudalianchi are discussed in this paper. The authors account for a mantle origin for the natural gas in the area, on the basis of the components of the gas and the magma inclusions, as well as a correlation of isotopic con stitutions S,Sr,Nd,Pb,etc.
ON THE SEDIMENTATION OF THE BARRIER BAR AND SLOPE APRON OF THE DAMOGUAIHE FORMATION, UPPER JURASSIC, IN THE WURXUN DEPRESSION, THE HAILAR BASIN
Shen Feng, Zhang Jinliang
1992, 14(2): 204-212. doi: 10.11781/sysydz199202204
Abstract:
Based on the data of drilling cores, seismic stratigraphy and loggings, the sedimentary analysis are made on the barrier bar and slope apron in the Damoguaihe Formation of the Wurhe Depression. Barrier bars distributed in the area of shallow water of lake shore, which are parallel to the lake strandline,and associated with restricted mudstone and coal layers, all together composing of sedi mentary sequences of hundreds of metres thick. Most of barrier sandstones are transgressive-type, characterized by bedding cycles with the sequence of fine-coarse-fine cycles. Slope apron is a type of sandbody newly discovered in Wurxun Dpression, and usually distributed in the onshore-offshore slope environments. It mainly consists of intraclastics and laminated sandstone, interbedded with dark mudstone. The orientation of intraclastics in the area reveals wave action. Slope apron sandbodies spreading parallel to sedimentary slope,are asymetric mound shape along the section in the direction of dip, being steep towards lake shoreline while gently dipping basinward.
A PRELIMINARY STUDY ON RESERVOIRS (BODIES)
Jia Zhenyuan
1992, 14(2): 213-215. doi: 10.11781/sysydz199202213
Abstract:
Oil/gas reservoirs are one of the objectives for the geological explorations in petroliferous basins. However, reservoir evaluation is directly related to the assessment of oil/gas in sedimentary basins. Not only the study is necessary throughout the activities of petroleum exploration, but even more important in the development of oil/gas fields. Nowadays, the understanding, analysis and evaluation of the reservoir become the foundamental topics in the study of oil/gas reservoirs. Therefore, it is suggested that the study consists of the following three fields (topics): the regional explorations, oil/gas exploration,and the development of reservoirs.