| 其他摘要 | Based on the theories of petroleum geology and organic geochemistry, comprehensively making use of the data of geology, geochemistry, geophysics and analytical testing, integrating the basin analysis and new theories of the dynamics of oil-gas accumulations and the fluid compartment, the elements and process of the petroleum system in the southwest area of Dongying depression have been studied comprehensively. The oil-gas accumulation system has been subdivided and evaluated in petroleum system for the first time. The geological pattern of oil-gas accumulation has been established and the formation mechanism of the hydrocarbon accumulation has been discussed. The distribution characteristics and the controlling factors of oil and gas have also been summarized systematically. At last, the further exploration strategy has been suggested. The main understandings are as follows.(1) Based on the sedimentation infill in this area, the Tertiary system has been divided into five sequences. The regional unconformities between the Guantao Formation and underlying strata and between Kongdian Formation and underlying Mesozoic Erathem are advantageous places to accumulate for the oil-gas. The stratigraphic framework is obviously controlled by structure. The Gaoqing fault and Shicun fault not only control the tectonic-sedimentary development, stratigraphic framework and distribution of sedimentary system in the Boxing sub-depression, but also play a very important role in the formation of source rock and reservoirs, the migration and accumulation of oil and gas.The geological elements and process of the Boxing petroleum system have been studied arefully. It shows that there were favorable formation conditions of hydrocarbon accumulation in the oxing petroleum system. The sequences Es4y; and Es3 with different geochemical characters are the ain source rocks in this petroleum system. The oil and gas discovered up to now can be classified as Es~3type, Es~4type and mixture type of both according to the geochemical features of the source rocks. There are abundant reservoir strata in the petroleum system. Three regional cap rocks in sequences Es~3,Es~4 and Guantao Formation have been recognized; there were three kinds of source-reservoir-seal association in Boxing petroleum system. The Guantao-Minghuazhen period in the late tertiary was main stage of oil-gas generation, migration and accumulation.The types and characteristics of the oil-gas pools in the Boxing petroleum system have been summarized systematically and characteristics of their dimensional distribution were further discussed. The structural pools were recognized in Chunhua, Xiaoying and Zhenglizhuang. The stratigraphic pools and complex pools of structure and strata pools have been revealed in Gaoqing fault zone and Jinjia slope area. Lithologic pools and complex of structural and lithologic pool were obvious in the area of Liangjialou, Qiaozhuang and Daluhu. Sequence Dongying and Mesozoic Erathem were characterized as stratigraphic pools and complex of structural and stratigraphic pools.(4) The definition and new classification scheme of the oil-gas accumulation system in petroleum system have been suggested for the first time in detailed exploration and complex accumulation area. The oil-gas accumulation system was defined as a relative independence unit of oil and gas migration and accumulation in petroleum system. The classification principle and methods for oil-gas accumulation system have also been suggested. Four oil-gas accumulation systems were suggested, they are: system of Gaoqing fault zone in the west, system of Jinjia-Zhenglizhuang-Fanjia in the middle, system of Chunhua-Liangjialou in the east and Xiaoying-Pingfangwang in the north; each of them has been analyzed and evaluated. All these system were further divided into 8 sub-systems; the structure played a controlling role in the oil-gas accumulation in each sub-system.(5) The dynamic mechanism of the oil-gas accumulation can be ascribed to self-source and sealing mechanism and external-source and opening mechanism according to the features of the formation pressure and the oil-gas accumulation in the area. The mechanism of migration and accumulation in the area has been explained according to the theory of fluid compartment, two kinds of accumulation models have been suggested, one of them was inner compartment accumulation with high abnormal pressure, and another was external compartment accumulation with normal pressure. They belong to self-source mechanism and external-source mechanism respectively, but most of them are accumulated in the compartment.(6) Based on inclusions data, history of hydrocarbon generation, second migration and accumulation, and the structure, two stages of oil-gas accumulation in the Boxing area has been suggested. The accumulation in Guantao-Minghuazhen period of the Tertiary was more important than that in early stage. The pools located in the north and east Boxing formed earlier than that located in the west and Jinjia area of the south slope, the main time of accumulation for the latter was approximately in the middle or late Minghuazhen period and it can last to quaternary.(7) The basic characteristics of oil-gas accumulation and the controlling factors have been analyzed systematically. The oil and gas were mainly accumulated in positive structural belt located in the center and margin of the depression. The distribution of oil and gas was influenced by the structural background, fault, lithology, unconformity and regional cap rocks etc. The further exploration target has been suggested. |
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