1993 Vol. 15, No. 4

Display Method:
A NEW UNDERSTANDING OF THE CHARACTERISTICS OF PETROLEUM GEOLOGY IN THE KESHI DEPRESSION, SOUTHWEST TARIM
Chen Ronglin, Hu Min, Zhu Hongfa, Chen Yue, Xu Xiang
1993, 15(4): 319-324. doi: 10.11781/sysydz199304319
Abstract:
With a new understanding of petroleum geologic conditions in the Keshi Depression, southwest Tarim, the authors believe that the middle Jurassic Yangye Formation is the major source rocks in the Meso-Cenozoic systems of the area, the Kezilesu Gr. aeolian sandstones of the Lower Cretaceous could be excellent reservoirs and the overlying Upper Cretaceous and Paleogene systems are well-developed regional multiseals, among which the Artashi Fr. gypsum rocks of Palaeocene would be the best. Therefore the source rock, reservoir and regional seals may vertically and horizontally compose of an oil/gas assemblage in the depression. Based on the above considerations, a breakthrough in oil/gas exploration would be expected in proper structures.
YENSHANIAN OIL/GAS GENERATION AND EVOLUTION IN WEST SICHUAN AND ITS OIL/GAS EXPLORATION PROSPECTS
Tao Hai
1993, 15(4): 325-334. doi: 10.11781/sysydz199304325
Abstract:
Since the Yenshanian movement is a peak stage for oil/gas generation of the Triassic source rocks in west Sichuan, the tectonic evolution in this stage would be significant for oil/gas accumulation in the area. On the basis of tectonic settings and sedimentary characters, the tectonic evolution in west Sichuan can be divided into three developing stages of upliftings and depressions, compressional foldings and shrinking subsidence, among which the upliftings play a significant part in the distribution of gas pools in west Sichuan. The west Sichuan Area then can be grouped by different structural belts of the Longquanshan fault-folded belt in east, the uplifting fault-folded belt in south, the steep-slope fault-folded belt in front of the Longmenshan in west and the depressional zone in the central part based on the present-day tectonic framework and the characters of the Yenshanian tectonic evolution. The superimposed areas between the upliftings or slope and the fault-folded belts mentioned above developed in the Yenshanian Period are most promising prospects for oil/gas exploration.
ON THE DYNAMIC RESEARCH OF THE DEEP-SEATED STRUCTURE FOR THE BASIN-FOLD-MOUNTAIN SYSTEM IN YANGTZE AREA
Fan Xiaolin, Lu Guoxin, Jiang Hongkan
1993, 15(4): 335-342. doi: 10.11781/sysydz199304335
Abstract:
According to the data of seismic sounding, magnetotelluric sounding and the geother-mal flow measurement, a variety of planimetric maps and diagrams have been charted. Compared with the results of the regional geology and lithology research, the characteristic of the physical properties of the lithosphere (velocity, density, resistivity, heat flow etc.) in Yangtze area have been analyzed comprehensively. This paper has also researched the dynamical condition of the basin-fold-mountain system formed and evolved under new global tectonic regime since Mesozoic.
ON THE DISTRIBUTION OF FLUID PROPERTIES AND GEOCHEMICAL MODEL IN RESERVOIR DESCRIPTION
Xiong Qihua, Fang Chaoliang, Zhang Zhihuan, Ji Fahua
1993, 15(4): 343-349. doi: 10.11781/sysydz199304343
Abstract:
With the development of the theory on oil reservoir description, the studies on the distribution of fluid properties and geochemical models have become an important part of reservoir description. In this paper, the case studies were taken from the heavy viscous oil pools in the 1,2,3 sections of the Shahejia Fr. in the Lengdong-Leijia Region. Furthermore, the authors established a 3-D geochemical model with a computer by using Kriging technology on the basis of comprehensive analysis on physical and geochemical properties of fluid and the distribution model of fluid properties. Finally, a complete set of techniques for establishing a geochemical model was summarized in the paper.
THE DISTRIBUTION OF SEDIMENTARY FACIES IN THE CAMBRIAN SYSTEM OF THE YANGTZE AREA
Zhang Xinguo
1993, 15(4): 350-360. doi: 10.11781/sysydz199304350
Abstract:
Based on the studies of sedimentology and petrology from 13 field profiles and the comprehensive analysis on the sites of 285 profiles, three regional profiles were established. Furthermore, the sedimentary facies over the whole Yangtze region was systematically studied in detail, which also resulted in sedimentary facies maps respectively for early and middle-late Cambrian systems and a clear explanation of the facies distribution and its main properties in the area.
THE IMPLICATIONS OF PETROLEUM GEOLOGY OF LACUSTRINE CARBONATE ROCKS
Zhou Shuxin, Wang Jianguo
1993, 15(4): 361-369. doi: 10.11781/sysydz199304361
Abstract:
The petroleum potential, reservoir conditions, the types of oil/gas pools and exploratory method of hidden oil/gas traps developed in lacustrine carbonate rocks were discussed. It is concluded that the carbonate rocks in semi-lacustrine and deep lacustrine facies would be good source rocks;and limestones (dolomites) of beach and bioherm facies may be regarded as favourable reservoirs. While their reservoir spaces include primary porosity, secondary corroded hollows and caverns, fissures and composite pores. Lithologic and stratigraphic traps are dominant, along with diagenetic and structural traps as less common oil/gas pools. Moreover, from various angles,the paper comes to a brief conclusion on the research approaches and exploratory methods for hidden oil/gas pools in lacustrine carbonate rocks.
ON THE PROPERTY OF THE BASEMENT FORMATION IN THE PALEOZOIC BASINS OF THE YANGTZE AREA
Shan Xianglin
1993, 15(4): 370-384. doi: 10.11781/sysydz199304370
Abstract:
The basement duplex structures are widely developed in the Paleozoic basins of the Yangtze Area. The intermediate metamorphic and hypometamorphic basements in the lower structural level mainly consist of the metamorphic rocks attributed to the Archaean-Lower Proterozoic granulite-amphibolite facies and amphibolite-greenschist facies with the isotopic ages of 2500-3100 Ma and 2000-2500 Ma respectively, revealing the formation of continental core and blocks in two different stages. The epimetamorphic basements of the upper structural level are Composed of the Middle Proterozoic metamorphic rocks of low-grade greenschist facies with the isotopic ages of 1000-2000Ma. The intra-sialic orogenesis at the end of the Middle Proterozoic and the A-subduction unified the whole area as an immature pan-continent of which the northern and western developed into cratons with low stability.
GEOCHEMICAL CHARACTERISTICS OF LOW-MATURITY CRUDE OIL IN THE XINJIANG JIMSAR DEPRESSION AND ITS PETROLIFEROUS POTENTIAL
Wang Yutao
1993, 15(4): 385-393. doi: 10.11781/sysydz199304385
Abstract:
In this paper, the physical properties and geochemical characteristics of crude oil from No.6 drilling well of the Jimsar Depression were studied. Thereafter, the correlation with adjacent regions were carried out in order to evaluate petroliferous potential in the Depression.
ON THE PARAMETER FOR ASSESSING MATURITIES OF ORGANIC MATTER IN SOURCE ROCKS DURING ARTIFICIAL MATURATION EXPERIMENTS
Li Zhi
1993, 15(4): 394-403. doi: 10.11781/sysydz199304394
Abstract:
Vitrinite-rich brown coal was sampled for our artificial maturation experiments to set up a corresponding relationship between telocolinite vitrinite reflectance and heating temperature (R°-TPY). By using such a relation, we can assess the maturities of all kinds of source rocks during the artificial maturation. It is also noted that by using telocolinite vitrinite reflectance as a maturitty parameter, the evolution and oil generation behaviors of source rock exhibited in artificial maturation are quite similar to those observed in geological condition. Thus, the experimental achievements of artificial maturation can be easily applied in the quantitative assessment of subsurface petroleum generation without any correction.
POROSITY AND PERMEABILITY UNDER CONFINING PRESSURE CONDITION AND THEIR IMPORTANCE FOR GAS-RESERVOIR EVALUATION
Sun Tuo, Lin Wanxiang
1993, 15(4): 404-413. doi: 10.11781/sysydz199304404
Abstract:
By experiments the authors studied the pressure effects of rock formation on the development of porosity and permeablility and suggested the evaluating and grading mathods of relative physical property parameters suitable to unconventional reservoirs and gas-reservoirs. Furthermore, the sensitive extent of stress to reservoir was also discussed in the paper.
A NEW METHOD TO CALCULATE THE ANCIENT THICKNESS OF SEDIMENTARY SEQUENCES
Mou Zhonghai
1993, 15(4): 414-422. doi: 10.11781/sysydz199304414
Abstract:
As the study and calculation on the ancient thickness of sedimentary sequences used to be based on the data of drilling wells and loggings, the application of the calculation is limited by the number of drilling wells. In this paper, the density logging data is applied combining with the thickness estimated from seismic wave velocity and the percentage parameter of sandstones in order to get the ancient thickness of sedimentary sequences in various stages and levels throughout basins. In particular, the introduction of sandstone percentage makes it possible to calculate the ancient thickness of mixed and intermediate types of strata in the basins.
THE TERTIARY SPOROPOLLEN ASSEMBLAGE IN THE JIUQUAN BASIN AND THE PALAEOENVIRONMENT
Ma Jinqian
1993, 15(4): 423-435. doi: 10.11781/sysydz199304423
Abstract:
As sporopollen is the generative cell of maternal plants, a paleo-vegetation and paleo-climate may be partially and approximately revealed by using the sporopollen spectrum. However, the characteristics of sporopollen assemblages from various Tertialry sequences in the Jiuquan Basin are approached with an alternative method to substitute a sporopollen spectrum by a sporopollen assemblage pattern. The distributive characteristics of paleo-vegetations and paleo-climates during different stages of sedimentation are inferred by sporopollen assemblage and ecologic behaviour of plants, and sporopollen differentiation index are applied to analyse the changes in the pateoenvironments for various sequences. Thus the paper has revealed an internal relationship between sporopollen vegetation and paleoenvironment, which can provide scientific basis for petroleum exploration and research.