2002 Vol. 24, No. 5

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DISCOVERY AND EXPLORATION SIGNIFICANCE OF MICROFISSURE GRAIN LIMESTONE RESERVOIRS IN THE ORDOVICIAN YIJIANFANG FORMATION OF TAHE AREA
ZHAI Xiao-xian, YU Ren-lian, HE Fa-qi, ZHOU Jia-ju
2002, 24(5): 387-392. doi: 10.11781/sysydz200205387
Abstract:
Tahe area is located in the southern part of the Shaya Uplift,the Tarim Basin. A large-scale stratigraphic unconformable-paleokarst trap was formed on the background of the large-scale Ordovician fossil buried hill. The further exploration of the trap showed that reservoirs in the main part of the trap were the karst fissure-typed reservoirs of the Lower Ordovician Yingshan Formation,and the grain limestone pore-typed reservoirs of the Lower Ordovician Yijianfang Formation were newly discovered in the southern part of the trap. The storage space of this type of reservoirs was dominated by intergranular openings ang pinpoint-like solution openings,which were connected by microfissures and sutures to form 20-30m thick and 200 km2spread more wide-ranging layered pore-typed reservoivs. The further interpretation and treatment of imaging logging data revealed that the porosity of solution openings was about 5%. This type of reservoirs were mainly controlled by the distribution of tableland marginal bioclast-bank facies,and paulopost solution was advantageous to the improvement of their storage performance. The grain limestone reservoirs and the upperlying regional caprocks of the Middle-Upper Ordovician argillaceous limestone and the Lower Carboniferous mudstone constituted a good reservoir-caprock assemblage with good sealing performance. Under the multiple periods of high-mature hydrocarbon injection by hydrocarbon source areas,medium-light oil pools with good exploration benefits were formed. In some prospect wells completed,high-productive oil flow was obtained through acid fracturing treatment. This expressed tremendous potential of the exploration field.
BASIN SIMULATION AND RESOURCE PROSPECT ANALYSIS OF THE MAMUWUSU DEPRESSION IN THE BADANJILIN BASIN
XU XU-hui, JIANG Xing-ge, ZHU Jian-hui, ZHANG Yu-chang
2002, 24(5): 393-402. doi: 10.11781/sysydz200205393
Abstract:
Basin simulation is one of the important technology and method for the exploration evaluation of petroleum basins. Based on the TSM basin-simulation system and the exploration degree of the study area in this paper,a suitable basin-simulation method system and corresponding software system were established,and the buried history,thermal history,hydrocarbon-generating history and hydrocarbon migration and accumulation history of the Mamuwusu Depression were revealed emphatically.On these bases,the resource prospects of the study area were analysed.
STUDY ON THE SEALING PERFORMANCE OF MAJOR FAULTS IN THE YANGXIN SERIES OF THE PERMIAN, SOUTH SICHUAN AREA
WANG Hong hui
2002, 24(5): 403-406. doi: 10.11781/sysydz200205403
Abstract:
Larger storage spaces can be formed within and nearby major faulted zones. The problem is if and in what degree they are sealing. In this paper,the pool forming probability of major faulted zones was discussed,and three signs used to discern a fault is sealing or not were suggested,that is,a)high abnormal formation pressure,b) water types and mineralization degree representing sealing environments and c) longitudinal multiple pay beds,pressure systems and water types. The three signs for discernment are fit for not only carbonate rock regions such as the Permian of South Sichuan area but also other clastic rock sedimentary regions. Except for the Tongtian Fault and denuded regions of gypsum salt layers in South Sichuan area,many major faults buried underground have good sealing performance and are favorable for the migration,accumulation and preservation of oil and gas.
RELATIONSHIP BETWEEN THE CENOZOIC FAULTS AND HYDROCARBON IN THE LIAOHE BASIN
CHEN Zhen-yan, CHEN Yong-cheng, QIU Jing-tao, DING Xiu-chun
2002, 24(5): 407-412. doi: 10.11781/sysydz200205407
Abstract:
The Liaohe Basin is a rift basin with the main basin-forming period in the Cenozoic. Faulting and rifting were the dominant styles for the Cenozoic tectonic deformation. Episodic faulting resulted in the periodic extension and cont raction of sedimentary spaces and lakebasin scopes,and cont rolled source rocks,reservoirs andcap rocks as well as their assemblage characteristics. The development of faults played an important role in theenrichment of hydrocarbon,and cont rolled the migration and accumulation of hydrocarbon. In this paper,theinfluence of faults on hydrocarbon was summarized thoroughly and systematically. It was considered that majorfaults cont rolled the enrichment of hydrcarbon,and the development and evolution of faults had an important enfluence on hydrocarbon resources. Secondary fault stook an important part in the lateral plugging and redist ribution of hydrocarbon,and the opening property of fault s resulted in poor or rich hydrocarbon in different districts. Faults cont rolled the development of special reservoir f ractures,and played a critical role in the formationof traps. Therefore,correct understanding of faults will have very important significance to hydrocarbon exploration.
CHARACTERISTICS AND FORMING CONDITIONS OF LAKE-FACIES CARBONATE-ROCK OIL AND GAS POOLS IN THE NANYISHAN STRUCTURE OF THE QAIDAM BASIN
GAN Gui-yuan, WEI Cheng-zhang, CHANG Qing-ping, YAN Xiao-lan, CUI Jun, WANG An-min, CHEN Deng-qian
2002, 24(5): 413-417. doi: 10.11781/sysydz200205413
Abstract:
As a typical example of lake-facies carbonate-rock oil and gas pools consisted by shallow oil pools and medium-deep gas condensate pools,Nanyishan oil and gas field in the Qaidam Basin has altogether four sets of hydrocarbon source rocks. The whole stratigraphic profile is dominated by argillite,micritic carbonate rock comes second. The reservoirs of hydrocarbon are carbonate rocks,including argillaceous micritic dolostone,argillaceous micritic limestone,micritic limestone,algal limestone,etc. The storage spaces are mainly intercrystal pores,intergranular pores,solution openings,fissures and karst caves. The reservoirs,which have the thickness of 2-5m in general,have rather stable plane distribution. Tectonic fractures are all well-developed from surface to underground. The clear reducing of seismic-wave velocity and abnormal high-pressure are observed in the medium-deep layers of hydrocarbon-distributive areas. The fission-track testing of fracture-infilling calcite revealed that fractures occurred before the generation and migration of hydrocarbon. The analysis of biomarkers showed that hydrocarbon come from source rocks deeper than 4 300m.
FORMATIVE LAWS OF DEEP NATURAL GAS RESERVOIR IN DU-QIAO-BAI AREAS, DONGPU DEPRESSION OF BOHAI BAY BASIN
SU Yu-shan, ZHANG Lian-meng, WU Li-zhi, WANG Xing-wu
2002, 24(5): 418-422. doi: 10.11781/sysydz200205418
Abstract:
The three petroliferous structures,i.e.,Qiaokou Baimiao and Duzhai in Du-Qiao-Bai areas,Dongpu depression constitute an enrichment area of deep natural gas with a significant resources background. On the basis of detailed structural explanation and new insights into sedimeutary facies of reservoirs,the paper analyzes the deep oil/gas reservoirs in Du-Qiao-Bai areas,in terms of formative conditions and constraints of oil/gas reservoirs,progressively the laws of oil/gas reservoirs are derived. Duzhai area with a deep sag background and simple structure is a large lithologic gas-bearing zone;and structurally-lithologically controlled gas condensate reservoirs are developed in Qiaokou area;and Baimiao area is characterized by the development of lithologically-structurally controlled gas reservoirs with oil rings,whose reservoir formative conditions are rather complex.
STUDY ON THE INJURING MECHANISM OF DIABASE RESERVOIRS IN SHENGLI OIL DISTRICT
LI Shu-fang, PAN Mao
2002, 24(5): 423-426. doi: 10.11781/sysydz200205423
Abstract:
The potential injuring factors and mechanism of igneous reservoirs,which are a kind of special lithologic reservoirs,are both difficult geological problems need to be studied. Selecting diabase reservoirs as study objects,using at present advanced microcosmic analysing and testing technologies and starting with microcosmic matter composition and structure in this paper,the potential injuring factors and mechanism of diabase reservoirs as well as their research method and train of thoughts were studied. This will be of directive significance for the exploration and development of the same kind of reservoirs and the same kind of research.
AN APPROACH TO THE LOWER LIMIT VALUES OF ORGANIC CARBON CONTENT IN OVERMATURED CARBONATE SOURCE ROCKS-WITH ORDOVICIAN MAJIAGOU FORMATION IN ORDOS BASIN AS AN EXAMPLE
CHEN Yi-cai, SHEN Zhong-min, LI Yan-jun, GUO Xiu-ying, LÜ Qiang, ZHANG Jun, SHI Xiao-ying
2002, 24(5): 427-430. doi: 10.11781/sysydz200205427
Abstract:
The phase state of hydrocarbons formed in carbonate source rocks at overmatured stage change from oil into wet and dry gases. When the carbonate rocks at overmatured stage act as gas-prone source rocks,their lower limit values of organic carbon content depend not only on the content of absorbed hydrocarbons,organic types and thermal evolution levels,but on the mechanisms and conditions of hydrocarbon expulsion to a certain extent. With the overmatured carbonate rocks of Ordovician Majiagou in the Ordos Basin as an example,first the paper made quantitative analyses on absorbed gaseous hydrocarbons generated,using the methods of hydrocarbon acidolysis from tanked cuttings,residual gas saturation,and geochemical analyses of whole hydrocarbons;then estimated the lower limit values of organic carbon content to be 0.03%-0.06% and further approached on the lower limit of organic carbon content combined with different hydrocarbon expulsion mechanisms.
STUDY ON THE GEOCHEMICAL EFFECTS OF VERTICAL HYDROCARBON MICROMIGRATION AND THEIR MECHANISM
TANG Yu-ping, LIU Yun-li
2002, 24(5): 431-436. doi: 10.11781/sysydz200205431
Abstract:
Vertical hydrocarbon micromigration (caprock and above) resulting in near-surface hydrocarbon anomalies is the theoretical basis and applied premise of geochemical hydrocarbon exploration. The objective exi-stence of vertical hydrocarbon micromigration showed that surface geochemical exploration anomalies were like "a river with sources". The differences of micromigration in the different parts of oil and gas pools revealed the effectiveness of geochemical hydrocarbon exploration. Based on teh geochemical fruits of surface and drilled wells and according to the positive migration gradient of various indexes,the correlation of halo sources and the structural gradient that hydrocarbon is getting lighter upwards,which is widespread in oil and gas wells,the objective existence of vertical hydrocarbon micromigration was revealed,the importance of microfracture network systems was emphasized,the mechanism of micromigration was discussed,and the genetic mechanism of surface geochemical exploration anomalies was well interpreted in this paper.
FLUID INCLUSIONS AND PHASES OF PETROLEUM INFILLING AND MIGRATION IN KELA-2 GAS POOL, TARIM BASIN
TAO Shi-zhen, QIN Sheng-fei
2002, 24(5): 437-440. doi: 10.11781/sysydz200205437
Abstract:
Based on the thin section observasions and diagenetic study,the fluid inclusions from Kela-2 gas pool,the present largest gas reservoir of the country are analysed,resulted in the parameters of trapping temperature and salinity of abiogenic inlusions in salty fluid associated with organic inclusions,and physical parameters and compositional data of organic inclusions,thus the sequential order of fluid inclusion formation can be inferred,and the palaeogeotemperature gradients of different diagenetic phases in upper Cretaceous calculated by a linear regression. Finally the infilling phases,and characteristics of evolution and migration of oil/gas,and resources potential in Kela gas pool are analysed.
SANDBOX SIMULATION OF SALTROCK PLASTIC FLOW CONTROLLED BY FAULTS IN THE KUCHE DEPRESSION OF THE TARIM BASIN AND ITS INFLUENCE ON OVERLYING STRATIGRAPHIC STRUCTURES
WANG Zi-yu
2002, 24(5): 441-445. doi: 10.11781/sysydz200205441
Abstract:
Taking the Beiqiu Anticline in the Kuche Depression of the Tarim Basin as the actual structural style of the simulation experiment,the Cenozoic rock and saltrock were sampled and analysed for lithomechanical parameters (i.e.,elastic modulus,Poisson's ratio,compressive strength,etc.). By theoretical calculation and experiment,vaseline and loose fine sand were chosen as experimental material based on the similarity principle. Using the bilateral-compressive model. the saltrock plastic flow controlled by faults and its influence on overlying stratigraphic structures were simulated in a sandbox. The results revealed that a) the structural style of the Beiqiu Anticline type in the Kuche Depression was formed by underlying saltrock plastic flow under the control of faults,and the plastic flow of saltrock and the formation of overlying caprock structures were closely related to the time and velocity of tectonic processess,displaying brittle in the rapid and short-time process or plastic in the slow and long-time process;b)the boundary occurrence of faults was one of the major factors controlling the direction of saltrock flow;c) the change of saltrock thickness was jointly affected by plastic flow and tectonic processes,and complex structure deformation existed within the inner of saltrock;d) the salt-rock interaction was not well coordinated,and the "disjunctive" appearance was shown in the boundary;and e) the lithomechanical properties of underlying rock layers affected and controlled the development of overlying rock structures,though the overlying strata may have the identical lithomechanical properties.
AN APPROACH ON THE DEVELOPMENT TECHNOLOGIES OF FISSURE-KARST CAVE-TYPED HYDROCARBON POOLS IN CARBONATE ROCK
HUANG Xiao-te
2002, 24(5): 446-449. doi: 10.11781/sysydz200205446
Abstract:
The fissure-karst cave-typed hydrocarbon pool in carbonate rock is one of the most developed types of hydrocarbon pools for the marine strata of the Tarim Basin in the western part of China. Its most important feature is that its storage spaces are dominated by fissures and karst caves. The reservoirs have rather strong heterogeneity.The log ging and seismic data are very difficult to dist inguish. Besides,its development is very much different from ty pical clast icrock hydrocarbon pools in China. During the development process of Tahe oilf ield in Xinjiang,the wells brought into production only took 10 percent,and a large part of wells were brought into production after the acid fracturing treatment. In this paper,the productive features of S-70 well after several acid fracturing treatments were used to analyse the reservoir characteristics of oil pools,and the development technologies of fissure-karst cave-typed hydrocarbon pools were discussed.
APPLICATION OF SINGLE SANDLAYER GEOLOGIC CURVATURE ANALYSIS TO FRACTURE PREDICTION
HU Zong-quan, LIAO Hong-wei, LIU Ren-he
2002, 24(5): 450-454. doi: 10.11781/sysydz200205450
Abstract:
As a traditional fracture-predicting method,curvature analysis was gradually improved in the long period of application. The geologic curvature used in this paper is a new kind of curvature-calculating method for geologic layers,which processes strictness in mathematics and practical significance in geology. The geologic targets of this research are three sandlayers with stable distribution laterally in a certain Jurassic formation. The previous research of this area investigated fracture distribution rules by the supersurface structural map of the overall formation;only a series of simple and qualitative conclusions were obtained about the relation between structure and fracture distribution. To reveal the controlling effect of structure upon fracture distribution,the structural map of each sandlayer supersurface was interpreted accurately with three-dimensional seismic data,the supersurface geologic curvature of each sandlayer was calculated with the new improved geologic curvature-calculating method,and the geologic curvature values were used as fracture-predicting parameters. Research outputs indicate that there are apparent differences between the distribution rules and values of geologic curvature for each sandlayer,the overall difference among the curvature values of each sandlayer has a very good matching relation with the overall difference among the production capacity of each sandlayer,and fine statistical relation exists between the natural production capacity and geologic curvature value of each well point in each sandlayer. Curvature analysis proved the existence of compound structures in the study area,and revealed that fractures often develop in the superimposed of structures. All this conclusions are of significance for fracture prediction before drilling.
STUDY ON THE SIMULATION AND APPLICATION MIGRATION PATHWAYS
JIANG Xing-ge, LÜ Jian-hong, FAN Yun-he
2002, 24(5): 455-459. doi: 10.11781/sysydz200205455
Abstract:
The way and direction of secondary hydrocarbon migration are of decisive significance to concrete pointing out the occurrence location of hydrocarbon resources in basins. In delivery layers,the efforts driving hydrocarbon are mainly buoyancy and capillary force,and caprock plays an role of capillary resistance. Thus,the form and space distribution of caprock become important sealing factors to affect migration pathways. According to the geometric form features of caprock in this paper,the simulation models of migration pathways were established,and microcomputer softwares were developed and put into operation and enforcement. The application of migration pathway simulation to a basin reflected that it was in keeping with the known exploration situation on the whole. It can examine the geological concept of periodic hydrocarbon migration,reveal the process of migration,and predict the possible position of migration and accumulation.
IDENTIFICATION AND EVALUATION TECHNOLOGIES OF GAS POOLS IN CHENJIAZHUANG GAS-WELL DISTRICT
LI min, FU Qing-xiang, HE Hui
2002, 24(5): 460-463. doi: 10.11781/sysydz200205460
Abstract:
The detection and evaluation technologies of underground reservoirs and fluid properties including plane detection and depth detection are new unconventional hydrocarbon detection and evaluation technologies developed recent years. In order to find out the best gas-bearing regional distribution and depth range of Chen-jiazhuang gasfield,field tests were conducted in the gas well district. The practice proved that the detection results of gas-bearing range had better correlativity when compared with the interpreted results of seismic bright spots. As with portable,low-cost and high-efficiency features,these technologies have great prospects for popularization.
APPLICATION OF THE SUBTLE OBJECT PROCESSING OF SEISMIC DATA TO SEQUENCE STRATIGRAPHY
ZHANG Qin, CAO Si-yuan, ZHU Xiao-min, SONG Gang
2002, 24(5): 464-468. doi: 10.11781/sysydz200205464
Abstract:
With the development of high resolution sequence stratigraphy,it is necessary to use high resolution seismic exploration technology to do subtle object processing in order to seek concealed stratigraphic traps. Based on the Fourier transformation and with the characteristics of time and frequency localization,the wavelet theory can raise the signal to noise ratio and resolution of seismic data. In the study of the Jurassic sequence stratigraphy in Fudong Slope area of the Junggar Basin,the application of wavelet processing software WTDECON has greatly improved the signal to noise ratio and the resolution in seismic sections. In addition,six delta front fluxoturbidite fan sandbodies were ascertained in the Sangonghe Formation. By the subtle object processing of seismic data,seismic inversion and trace integration section processing,the distribution location of deep water fluxoturbidite fan sandbodies and the properties of sandstone were confirmed. This will provide reliable geophysical information for seeking concealed lithologic traps with self grown and self reserved oil and gas in the Jurassic of Fudong Slope area in the Junggar Basin.
APPLICATION OF THE 3-D FLUORESCENCE FINGERPRINT TECHNOLOGY TO THE ANALYSIS OF OIL SOURCES IN DINGJIAWUZI, THE DONGYING DEPRESSION
SONG Shu-jun, LI Xian-fu, FEI Qi
2002, 24(5): 469-473. doi: 10.11781/sysydz200205469
Abstract:
The 3-D fluorescence fingerprint technology has wide application prospects in the correlation of oil sources,the discernment of hydrocarbon properties for traps,the evaluation of traps,etc. In this paper,it was used to analyse oil sources in Dingjiawuxi area,the Dongying Depression. The results show that this area has multisource oil,and the oil sources can be divided into five types,among which type "2" and "2'" are dominant.
ON THE DIRECTION OF PETROLEUM EXPLORATION AND DEVELOPMENT OVERSEAS UNDER NEW SITUATION
SHI Dan-ni, WANG Jun, ZHANG Yan-qiu, XIE Bo
2002, 24(5): 474-479. doi: 10.11781/sysydz200205474
Abstract:
The paper starts with the uneven global petroleum distribution to conclude that Middle East,North Africa,Middle Asia-Russia are rated as the major distribution areas of petroleum resources. The uneven distribution of oil/gas fields can be expressed by the differences in burial depth,basin and trap types. On this basis,it is proposed that Russia and Africa be the major and first targes for overseas petroleum exploration and development;Middle East be the important area to open up the market for petroleum exploration and development;and the coastal Caspian area,southeast and south Asian regions be the reserve areas of petroleum exploration and development overseas.