1989 Vol. 11, No. 1

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ON THE FORMATION CONDITIONS OF THE YAKELA OIL/GAS FIELD IN THE TARIM BASIN
He Haiquan, Zhang Zhongxian, Tang Yidan
1989, 11(1): 1-6. doi: 10.11781/sysydz198901001
Abstract:
The authors of this paper briefly describe the formative conditions of the Yakela Oil/Gas Field in the following aspects: oil generation, reservoirs, caps, traps, migration and preservation. Emphasis are laid on the analysis of main controlling factors, such as reservoirs and traps in oil/gas fields. It is concluded that the best formative condition of oil/gas pools is the presence of ancient remanent hills in the basin,which consist of Lower Ordovician and its underlying systems, and are directly draped with Triassic and Jurassic systems. Finally, it is suggested that this oil/gas field is a layer-block type of oil/gas pools controlled by lithology,in which the main body of reservoir space consists of a net of linked pores,caves and fractures surrounded by side water and bottom water.
COMMENTS ON EFFECTIVE SOURCE ROCKS
Sheng Zhiwei
1989, 11(1): 7-15. doi: 10.11781/sysydz198901007
Abstract:
In this paper, the concept of effective source rocks refers to those of source rocks in which the hydrocarbons already generated have been expelled or diffused out from their mature source rocks. Not only the meth-ods and procedures are introduced in detail to distinguish the effective source rocks from ineffective ones,but also the various geological factors influencing the development and distribution of effective source rocks are discussed,and the relationship between the effective source rocks and oil/gas pools are studied as well. It is pointed out that only the effective source rocks are the real source of oil and gas.
ON PETROLEUM SOURCE AND MATURATION CHARACTERISTICS OF THE ORGANIC MATTER OF CAMBRIAN AND MIDDLE-UPPER PROTEROZOIC IN KUANCHENG REGION OF NORTHERN HEBEI PROVINCE
Liu Baoquan, Fang Jie
1989, 11(1): 16-32. doi: 10.11781/sysydz198901016
Abstract:
The Middle-Upper Proterozoic and Cambrian sediments are well developed in Yanliao Subsidence Belt of North China and the thickness of the sedimentary strata is almost 10 Km in which oil/gas shows are widespreaded. Based on the outcropped stratigraphic profile of the area, the oil generation conditions, geochemical characteristics, and oil source of the Middle-Upper Proterozoic and Cambrian systems are studied using many analytical data. It is suggested that the dark grey-limestones and shales of Zit, Zih, Zcg, Zcch and Zqx are the good source rooks. The oil/gas shows in the area are mainly derived from the limestone of the Tielng Formation and the shales of the Hongshuizhuang Formation. The maturity of the organic matter in Jixian System of Middle-Upper Proterozoic is rather low and still remains in the oil generation stage,while those of the overlying and underlying Qing-beikou, Cambrian systems and Changcheng System have already entered the overmature stage.
GEOCHEMICAL CHARACTERISTICS OF HYDROCARBONS GENERATED FROM COALS OF THE LONGTAN FORMATION, THE JURONG BASIN
Shang Huiyun, Xu Weiming, Tong Zhneyan, Xia yan
1989, 11(1): 33-40. doi: 10.11781/sysydz198901033
Abstract:
In order to approach the possibility and scale of hydrocarbon generation of the Longtan Formation of Upper Permian System in the Jurong Basin, the paper studied the maceral composition and geochemical characteristics of coals. The result shows the coal of the Longtan Formation is in the evolutionary stage of gas-fat coals, the content of bitumen A is 4.89%; which is composed of more than 50% resin and asphaltene, and the content of aromatics is three times higher than that of saturated hydrocarbons.The organic matter is rich in higher plants, according to the analyses of GC,LC, IR spectroscopy and GC-MS. Furthermore, maceral examination and thermal simulated experiments were made, which showed that the content of exinite is 22.9%, and its productivity of liquid hydrocarbons is 36mg/g.c. The coal in the Longtan Formation is thought to have definite hydrocarbon generating potential.
APPROACHES ON THE OPTIMUM ORGANIZA TION OF THE GEOCHEMICAL EXPLORATIONS FOR PETROLEUM
Liu Congxi, Wang Huai
1989, 11(1): 41-49. doi: 10.11781/sysydz198901041
Abstract:
In view of the limitations of the individual methods used in oil/gas geochemical explorations,the optimization of organization of the various methods would bring the advantages of the geochemical exploration into full play. The main methods of the geochemical exploration and the practices at home and abroad are introduced in this paper. Based on the available informations and the reliabilities of the different oil/gas indicators, it is suggested that the optimum organization of geochemical methods should take the hydro-geochemistry method as the main body,supported by gaseous hydrocarbon method, methane isotopic method, AC method, ultraviolet absorption spectroscopy and fluorescence spectroscopy. Finally,the applications of the above methods and the relationships between them are also discussed with examples.
TIANFU MOVEMENT-A SIGNIFICANT FACTOR OF PERMIAN-TRIASSIC GAS POOLS IN THE SICHUAN BASIN
Zhang Guanqun
1989, 11(1): 50-55. doi: 10.11781/sysydz198901050
Abstract:
In the practices petroleum exploration in the Sichuan Basin, one would find that the Sichuan Movement can not be properly explained as a controlling factor on the formation of some structural traps. The author ot fhis paper reconstructs the ancient tectonics using the data of the sedimentation of Maanshan and Daanzhai formations. It is proposed that there was a sub-episode of Yanshanian Movement before the Sichuan Movement, and it brought about groups of contemporaneous folds by differential of uplift and subsidence in limited scale. Such a movement is named in the paper as "Tianfu Movement" which would be quite important for the oil/gas explorations in Permian and Triassic systems, even in Carboniferous System of the Sichuan Basin.
THERMAL CHARACTERISTICS AND PETROLIFEROUS PROSPECTS OF MARINE CARBONATE ROCKS OF NANPANJIANG AREA
Zuo Xianqiong
1989, 11(1): 56-61. doi: 10.11781/sysydz198901056
Abstract:
Combined with the characteristics of the thermal evolution of carbonate rocks in the area, the paper studies the regularities of thermal evolution of sedimentary organic matter. Clear explanation of lower limit values for organic carbon contents in carbonate source rocks and of relations between H/C and Ro for kerogen at different stages of thermal evolution are given. In addition, the limits of petroliferous evolution of kerogen and exploration prospect are discussed.
RELATIONSHIP BETWEEN DIAGENESIS AND RESERVOIR PROPERTIES IN JURASSIC DAANZHAI MEMBER, NORTHERN SICHUAN
Huang Hengquan
1989, 11(1): 62-75. doi: 10.11781/sysydz198901062
Abstract:
Based on the examinations of rock sections, scanning electronic microscope and casting sections,and porosity and permeability of rocks,the author studied the diagenesis and reservoir properties in details. Diagenesis involves processes as follows. 1.transformation 2.replacement 3.compaction and pressolution 4.biological activity 5.cementation, 6.solution, 7.recry-stallization, as a combination of which diagenetical fractures and structural fractures developed. Notice should be paid to semi-filled-unfilled shells and horizontal fractures between cements. Interstitial pores, inter-stitial pores and solution pores within shells, and solution pores formed in late diagenesis stage, and microfractures resulted from pressolution which were eventually collaborated with diagenesis fractures, diagenetic solution fractures, structural fractures could improve reservoir properties. It is thought Daanzhai Menber is composed of reservoir of pore-fracture type, and suggestions for oil and gas exploration are provided.
DIFFERENTIAL SCANNING COLORIMETRY STUDIES ON KEROGEN
Wang Tingfen, Lu Shaoxin, Qin Kuangzong
1989, 11(1): 76-83. doi: 10.11781/sysydz198901076
Abstract:
In order to study thermodegration of kerogen,the samples of kerogen in oil shales from Fushun,Maoming and Huang Xian and organic matter of brown coal from Huang Xian were investigated with differential scanning colorimetry(DSC) technique. The relations between the types of parent materials and oil-gas generating patential were discussed based on the parameter variation of kerogen structures. There are two peaks in all DSC curves for all types of kerogens, which are combustion peaks of carbon aliphaticity and carbon aromaticity respectively. The areas of the two peaks can be used to calculate carbon aliphaticity and carbon aromaticity of structure parameters of kerogen. These two parameters are related to the types and maturity of kerogen, and to a certain extent, they may represent potential of oil and gas generation for kerogen.
LITHOLOGIC EFFECTS UPON THE STUDY OF CLAYSTONE COMPACTION USING THE DATA FROM TIME DIFFERENCE OF ACOUSTIC WAVE
Qin Ruozhe, Wang Zhongran
1989, 11(1): 84-90. doi: 10.11781/sysydz198901084
Abstract:
Based on the lithological homogeneity of claystones, logging data of time difference of acoustic wave have been used to study the porosity and compaction of claystones. The claystones in the continental basins of Eastern China are often sand-bearing. The readings of time difference can be strongly affectted by the variation in silt content of claystones. This is likely being neglectted, because it can not be identified from the information of natural potential logy. There are possibilities of error in selecting values of time difference and normal trend lines, and in geological explaination as well. The authors analyse these problems using acoustic log and actual information from the Qibei Depression and propose the right way to solve such problems.
PRELIMINARY STUDY ON THE ORIGIN OF IMMATURE OIL IN EVAPORITIC ENVIRONMENT
Zhang Fanyao
1989, 11(1): 91-97. doi: 10.11781/sysydz198901091
Abstract:
Based on the facts that immature crude oils discovered at home and abroad are related to the environment of evaporates, ex. the oil in the 1st section of the Qianjiang Formation encountered by Huan No.33 well in the Changqing Oilfield, the Tertiary immature oil in Shiqma region of Isreal, etc. The origin of immature crude oils in evaporitic environment is studied in this paper. The author briefly introduces and reviews the following opinions on the origin of immature oil proposed recently. 1.strong reductive environ-ment is favourable for the preservation and the transformation of organic matter in early stage, and 2.the types of organic matter are the prerequisite of the formation of immature oils. Thereafter, it is suggested that the oil generated in evaporates may firstly migrate upwards and then changes into an immature oil, based on the study of the oil generated in the evaporitic sediments of the Gulf of Suez, Egypt.
THE SPORO-POLLEN ASSEMBLAGES OF THE LOWER TERTIARY XIEJIASHAN FORMATION IN LIXIAN COUNTY OF HUNAN PROVINCE
Tong Chengxu
1989, 11(1): 98-104. doi: 10.11781/sysydz198901098
Abstract:
The sporo-pollen fossils of the Tertiary Xiejiashan Formation in Lixian County of Hunan Province can be devided into two assemblages. The first one widespreads through out the lower section of the Xiejiashan Formation, which partly consists of Ulmipollenites, U. minor, Plicapollis, Subtricolpollenites. The age of the assemblage is of late Paleocene. The second one distributes at the upper section of the Xiejiashan Formation, which is characterized by Tricolpits and Tricolporopollenites (Ulaceae, Fagaceae, Myrtaceae, Betulaceae) and the age is of early Eocene.