1997 Vol. 19, No. 2

Display Method:
TECTONIC ANALYSES AND HYDROCARBON DOMAINS IN THE MESOZOIC AND CENOZOIC FORELAND BASINS OF TARIM
Ding Daogui, Liu Weixin, Cui Kerui, Wang Daoxuan, Sun Shiqun
1997, 19(2): 97-107. doi: 10.11781/sysydz199702097
Abstract:
The formation and evolution of Mesozoic and Cenozoic Kuche-Baicheng and Kashi-Yecheng foreland basins in Tarim are related to the close of Tethys and long-range effects produced by the subduction and collision of Indian plate to Eurasian plate. It is mainly showed that the basement of Tarim Basin subducted intracontinentally to peripheral West Kunlun and Tianshan orogenic belts to form crust-stacked wedges, the thrust sheets of orogenic belts napped basinward in a large scale, and the basement of the basin flexurally subsided to form compressional foredeeps, By a large amount of fabric analyses and three-dimensional finite strain measures, the basinward napping distance of orogenic belts, the progressive metamorphic patterns and compressed volume of foreland basins and the trapping types and hydrocarbon domains formed are calculated.
AN APPROACH TO MAJOR TECTOGENESIS OF TARIM BASIN
Tang Liangjie
1997, 19(2): 108-114. doi: 10.11781/sysydz199702108
Abstract:
It is indicated that the embryo of modern Tarim basin was brought about by Tarim orogeneses. The midCaledonian movement resulted in that the introai-cratonic extensional Tarim basin during Cambrian-Ordovician transformed into a compressional basin during Silurian-Devonian. Because of early-Tianshan, and late-Tianshan orogeny and Indosinian orogeny, three tectonic inversions, block-faulting, elevation, erosion and peneplanation occurred, which affected the structural deformation of the Tarim to a large extent. Owing to the Himalayan movement, the Tianshan and Kunlun mountain belts around the basin rapidly compressed, shortened,uplifted, and denuded, and an intense flexural subsidence of the Tarim continental lithosphere took place. The major tectonic movements of the basin are related to streching, rifting, subduction and collision and closing atthe plate margins.
STRUCTURAL STYLES AND CHARACTERISTICS OF FOLD-THRUST BELTS IN SICHUAN FORELAND BASIN
Cai Liguo, Liu Hefu
1997, 19(2): 115-120. doi: 10.11781/sysydz199702115
Abstract:
The progressive thrusting and napping of Sichuan fold-thrust belts controlled the distribution and development of the main structural styles in the Sichuan foreland basin. In plane it can be divided into (1) ejective folded deformation belt in Chuandongnan area; (2) low and gentle anticlinal structural area in Chuanzhong uplift;and (3) low and steep-low and gentle folded belt of Chuanxibei and Chuandongbei. While it shows a zonality in plane, vertically the structural deformation appears in different levels, which can then be divided into (1) deepseated level; (2) middle-seated level; and (3) upper-seated level. On the whole, it is in a sandwich-like structure. The main structural types consist of basement thrust and nappe, imbricate thrust system, klippe, duplex,pop-up, triangle zone, fault-propagation fault-bend and gentle fold, etc.
A DIVISION OF CONTINENTAL SEQUENCE STRATIGRAPHY AND THE IDENTIFICATION OF ITS INTERFACE WITH HIGH RESOLUTION CORE ANALYSES AND WELL-LOGGING
Dong Qingshui, Cui Baochen, Li Xiang, Guo Wei
1997, 19(2): 121-126. doi: 10.11781/sysydz199702121
Abstract:
In a continental basin there are four types of parasequence with three patterns of overlappings, i. e. Ⅰ,Ⅱ typed aggradational parasequence set, aggressive parasequence set and regressive parasequence set I thereby the paper discussed the feasibility of the four-division plan for continental sequence stratigraphy, and proposed the terms of lacustrine dry system tract (LDST), lacustrine extend system tract (LEST), and lacustrine wrinkle system tract (LWST). It is summarized that sequence interfaces may be clarified into four types: regional angled unconformable contact, vocano-local unconformable contact, maximum exposural flushing surface of lacustrine wrinkle and regional onlapping unconformable contact, etc. Finally the paper suggested the followings may be considered as interfaces of parasequence: the bottom interface of oil-shale and organic-rich layer; the interface between the low-energy fine clastics and underlying calcareous concretion and slump structural layer, the rock facial plane characterized by a large scale abrupt increase of water depth I the top interface of a thick slump structural layer;and a thick muddy sedimental interface characterized by an abrupt color mutation.
DEPOSITIONAL MICROFACTES, RHYTHMS, CYCLES AND SEQUENCE STRATIGRAPHY OF QIXIA FORMATION IN ZHEJIANG PROVINCE, CHINA
He Haiqing
1997, 19(2): 127-132. doi: 10.11781/sysydz199702127
Abstract:
Based on the sedimentary microfacies and bioecologic analysis for the Qixia Formation of three sections in studied area, this paper summaried the depositional rhythms, cycles and sedimentary environment of Qixia Formation, and further analysed the characteristics of sequence boundary and depositional system tract. The results suggest that Qixia Formation in the study area was on the whole formed in a depositional setting of carbonate gradual slope that was subtidal, low-energied, open and non-barrier; and moreover two kinds of sequence boundaries and four sequences are recognized in Qixia Formation. According to the characteristics of sequence boundary and the stacking type of parasequences, it is divided into a transgressive system tract (TST) and a highstand system tract (HST).
THE RESEARCH OF PETROPHYSICS OF COAL RESERVOIRS AND SELECTED EXPLORATORY DISTRICTS OF COALBED METHANE AND RECOVERY
Wang Shengwei, Chen Zhonghui, Zhang Ming, Zhuang Xiaoli, Yang Shengke, Miao Suqing
1997, 19(2): 133-138. doi: 10.11781/sysydz199702133
Abstract:
Recently, the study of petrophysics of coal reservoirs was greatly advanced. The study contents have been expanded from the analysis of the pore-fracture system of coal reservoirs in the beginning to the evaluation of coal reservoirs permeability, gas saturation and CBM pool trap, from solid properties analysis of coal reservoirs to the relationship analysis between fluid formation, reserve and pore-fracture system, and from testing the physical mechanic properties of coal to the evaluation of coal reservoirs reformbility. The testing parameters of coal reservoirs were a few at the beginning but now are plentiful for systhetical evaluation of CBM extractability and forming conditions of CBM pool. The testing techniques of coal reservoirs have been developed and the description parameters of petrophysics of coal reservoirs have been changed from qualitative at the beginning to semi-quantitative or quantitative now. The research procedures and methods of petrophysics of coal reservoirs mainly depending on the artificial outcrop analysis of coal resservoirs have been tentatively built. The detial research districts of petrophysics of coal reservoirs expanded rapidly from exploratory districts of drilling CBM wells at the beginning to the other districts now, having acquired plentiful geological informations by the observation and research of artificial coalbed outcrop underground coal mine. The situation of complement and verify each other between the parameters evaluation of CBM wells and the parameters analysis of coalbed outcrop underground coal mine have been tentatively formed. Looking ahead the developing direction of the study of petrophysics of coal reservoirs, the authors believe that the study will show great significance in CBM exploration and development.
A PRELIMINARY ANALYSIS OF OIL-POOL FORMING CONDITIONS IN THE LATE PERIOD IN THE NORTHERN TARIM AREA
Sun Yan, Jia Chengzao
1997, 19(2): 139-147. doi: 10.11781/sysydz199702139
Abstract:
A whole process including oil-gas source,migration-accumulation and trap-preservation has been emphasized in the modern petroleum geology. From the Paleozoic to the Cenozoic Erathem there were rich oilgas sources and a well developed reservoir system;and various kinds of oil-gas pools have been discovered in the northern Tarim area. But up to now no oil-gas pools sourced from the Paleozoic in Cenozoic Erathem reservoirs are found in this area. According to numerous determinations of samples selected from the field,comprehensive comparision of collected data, and the observation and ahalyses of tectonic evolution,specially,the neotectonic movement and inversion tectonics,etc.,the oil pool forming condition in the late period in the northern Tarim area has been explained from three aspects: the oil-gas source,migration-accumulation and the Paleozoic sourced Cenozoic reservoir. Finally it is shown that the forward thrust fault block sequence of piggy-back pushing from the Tianshan Mountain to the Tarim basin,tensile structures with graben-horsts and strike slip transfer tectonics could become the oil-gas bearing local structures with oil pools formed in the late period.
ON CHARACTERS OF OIL/GAS AND POOL-FORMING MODEL IN THE MIDDLE TARIM BASIN
Zhou Xiaojin, Fan Ming, Qiu Yunyu
1997, 19(2): 148-152. doi: 10.11781/sysydz199702148
Abstract:
Based on a combination of the microcosmic characteristics of present industrial oil and gas,viscous crude oil and reservoir bitumen,and the macroscopic geological settings in the middle area of Tarim basin,the authors studied the models for petroleum pool-forming and evolution in that region. It is indicated that the present oil reservoirs there had formed mainly in the Himalayan pool-forming stage,however,the oil and gas in the early-formed pools were preserved only in the forms of reservoir bitumen and redox residual oil,as they being damaged to different extents. The present oil/gas reservoirs mainly consist of marine oils of miscible sources from the northwest and marine condensate gas and dry gas from the northeast.
RESULTS AND PROBLEMS OF OIL/GAS GEOCHEMICAL EXPLORATION IN THE RECENT YEARS IN CHINA
Zhao Kebin, Chen Jun, Liu Chongxi
1997, 19(2): 153-157. doi: 10.11781/sysydz199702153
Abstract:
For a key project during the 8th "Five-Year-Plan", the authors made a systematic study of the geochemical data collected from the major oil/gas-bearing basins in China. It is considered that the reliability of anomalies would be improved by studying the variation of geochemical background value with an oil/gas-bearing basin as a basic unit; and that it is important to acquire oil and gas information scientifically and use geochemical technology correctly; and that six indicators can be summed up including the identification of the characters of hydrocarbon gases in natural gas, and spectrometric parameters etc, as well as geophysical-geochemical prospecting technologies applied to explore oil/gas directly; and that the application of the technology with well geochemical logging has promising prospects.
DISCUSSION ON THE GEOCHEMICAL CHARACTERISTICS AND GENESES OF PERMIAN VISCOUS OILS AT THE NORTHWESTERN EDGE OF JUNGGAR BASIN
Wang Yutao, Hui Rongyao
1997, 19(2): 158-163. doi: 10.11781/sysydz199702158
Abstract:
By analysing the geochemical characteristics of viscous oils from Permian Wuerhe Formation (P2w) in the southern oil/gas region of V zone within faulted footwall slope area at the northwestern edge of Junggar Basin, it is discovered that the viscous oils have the special properties of low acidity, higher solidifying point and waxy content, alkane-bearing hydrocarbons, oxygen-bearing functional group lacking, unselective losses etc. and have obviously different geneses from secondary oxidized viscous oils in faulted upper plates-Based on the distribution and each geochemical character of hydrocarbons, it is considered that evapofractionation is the major reason to bring about the consistency changes of crude oils in this area.
CARBON ISOTOPE OF ETHANE APPLIED IN THE ANALYSES OF GENETIC TYPES OF NATURAL GAS
Gang Wenzhe, Gao Gang, Hao Shisheng, Zhu Lei
1997, 19(2): 164-167. doi: 10.11781/sysydz199702164
Abstract:
The correlation of carbon isotope of ethane and maturity is srudied by hydrous pyrolyses of carbonate rock, mudstone, oil shale, and coal. It is found that the carbon isotope of ethane both for sapropelic pyrolytic gas and humic pyrolytic gas obviousy shows an inheritance of mother materials, however, there is a differnece in their distributions for the two types of gas. In other words, the δl3C value of ethane for sapropelic natural gas is smal1er than -29%,(PDB), while the δl3C value for humic natural gas is greater than -29%,(PDB). It is concluded that the results either from hydrous pyrolytic experiments or from actual statistic figures indicate that δl3C value -29%, of ethane can be taken as a criterion to determine the genetic types of sapropelic or humic natural gas. It was used in studying the genetic types of natural gas in Tarim basin, which achieved good results.
DISTRIBUTING CHARACTERISTICS OF SEDIMENTARY FACIES BELTS AND SANDSTONE BODIES OF JURASSIC IN TURPAN-HAMI BASIN
Li Wengou, Liu Yiqun, Feng Qiao, Wang Wuhe, Yang Zhenxiang, Li Huaming
1997, 19(2): 168-172. doi: 10.11781/sysydz199702168
Abstract:
Alluvial fan, fluvial, lake, fan delta, braid river delta and meandering river delta facies sediments are widely developed in Jurassic in Turpan-Hami basin. The good reservoir sandstone bodies include the facies belts of underwater distributary channel of braid deltas front, underwater distributary channel of fan deltas front, stream channel bar of braid river and beach sands of shore shallow-lake in middle Jurassic (Xishanyao Formation, Sanjianfang Formation, Qiketai Formation). Its vertical development and lateral spreading will be an important subject of oilfield exploration in the future.
STUDY ON DIAGENESIS OF THE MIDDLE AND UPPER JURASSIC RESERVOIR IN TURPAN DEPRESSION
Liu Linyu
1997, 19(2): 173-178. doi: 10.11781/sysydz199702173
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The main diagenesis of the middle and upper Jurassic reservoirs in Turpan Depression is studied by means of the casting thin sections, scanning electron microscope, X-ray diffraction and physical properties. Compaction and cementation are the major factors turning the pore texture of reservoir worse; while dissolution is the major factor making the pore texture of reservoir better. Dissolution transformed the physical properties of reservoirs. Modified by dissolution, the clastic rock of Sanjianfang-Xishanyao Formation in the middle Jurassic became the most important reservoir of oil and gas with its high porosity and permeability in Turpan Depression.
GEOGRAPHIC INFORMATION SYSTEM: A NEW TECHNIQUE FOR PETROLEUM EXPLORATION AND DEVELOPMENT
Ye Deliao
1997, 19(2): 179-182. doi: 10.11781/sysydz199702179
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With an introduction of the basic principles of geographic information system (GIS), the paper discussed its application in petroleum exploration and development. A complete GIS can provide geologists a powerful tool for the inquiry, collection, analysis, display, modification and drawing of various data of hydrocarbon exploration and development. Especially, the application of 3-D visualization technigue will get a deeper understanding of geometries and characteristics of reservoirs, and hence improve the estimation ofreserves and increase the success ratio of prospection drilling.
THE CONFINING OF ARGILLACEOUS CAP ROCKS ON NATURAL GAS OF DIFFUSION PHASE AND ITS APPROACH
Fu Guang, Chen Zhangming, Wang Pengyan
1997, 19(2): 183-187. doi: 10.11781/sysydz199702183
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Based on a thorough study of the diffusion of natural gas through the cap rocks and its influential factors, the sealing of argilliaceous caprocks on natural gas in diffusive phase is analysed, suggesting that the sealing argillaceous cap rock on natural gas in a diffusion phase includes three forms, i. e a sealing (1) dependent of concentration, (2) of concentration and the quality of itself and (3) of the quality of itself.Considering the concentration difference of gas between a gas pool and its cap rock, the calculations of the diffusion rate of argillaceous cap rock and the diffusion rate of natural gas under unit concentration difference through the cap rock, etc. the authors inquire into the methods to study the three types of sealing capabiIity of argillaceous cap rock on natural gas in diffusion phase. The results of case study show that these methods are available, and can objectively reflect the actual sealing capability of argillaceous cap rocks.
A NEW METHOD OF QUANTITATIVE STATISTICS OF SECONDARY PORES IN SANDSTONE RESERVOIRS
Wang Shuyi
1997, 19(2): 188-191. doi: 10.11781/sysydz199702188
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Secondary pore is one of important types of reservoir space in sandstone reservoirs. It is not difficult to identify secondary pores with the petrographic method. however, it is when quantitative statistics of pore types are to be made, because secondary pores and primary pores were often connected to form into mixed pores resulted from intense corrosion. The paper proposed a method that combines the observed porosity and petrographic statistics, and clarified the samples into "intense corrosion" and "weak corrosion" types, so as to make their statistics respectively. The petrographic method was applied to get accurate statistics of the samples of "weak corrosion" type, while the affects of "intense corrosion" were determined on the basis of a observed porosity, and finally to obtain accurate quantitative statistical data.
1997, 19(2): 192-192. doi: 10.11781/sysydz199702192
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