Study On Sedimentary Facies And Advantageous Distrivbution Of Oil In The Chang 3-4+5 Oil Pools Of Triassic Yanchang Formation In Nanliang-Huachi Area

As the second largest sedimentary basin on land in China, the Ordos Basin covers 250,000 square kilometers and possesses abundant oil and gas resources with a bright prospect for the exploitation and development of oil and gas. It has been one of the important tactical areas for future exploitation and development of oil and gas in China.Nanliang-Huachi is the important generative area of oil in the Ordos basin. As two primary oil beds in Longdong area, the exploitation and development of Chang3-4+5 oil beds are significant for the development of Changqing Oilfield. To further study the rules of the hydrocarbon accumulation and distribution in the area, it is necessary to study sedimentary facies and advantageous distribution of oil and gas in the Chang3-4+5 oil beds of Nanliang-Huachi area in a detailed way.On the basis of the theories of sedimentary facies and petroleum geology, by means of geology investigations in the field and research indoors, combined with the dates of geological background, lithological association, sedimentary structure, geochemistry, chemical analysis of reservoir organic compound, the thesis studies the distribution rules of stratum and sandstone, the development rules of sedimentary subfacies, reservoir characteristics, oil resources ,the rules of accumulation and distribution of oil in Chang3-4+5 oil beds of Nanliang-Huachi area. The following results are obtained in the thesis:The Chang3 stratum is divided into 3 sub-stratums and the Chang 4+5 2 into 2 sub-stratums by various means. The thesis sets the boundaries of each stratum and describes lithological characteristics of the sub-stratums, which enables the classification of the sub-stratums in the studied area more reasonable and in a more detailed way.With identification of detrital composition and heavy mineral, and conduct of geochemistry REE analytic procedure, combined with traditional geology ways, the thesis aims at judging the various direction of provenance in the studied area in a comprehensive way. One is Northeastward, the borderline is lie in the Yuele-Huachi area. The other is southwestward. And there were mixed provenance area between south Huachi and ChengHao oil field.The Chang3-4+5 stratum was divided into 3 sorts ,and evaluated by clustering analysis with the parameters such as thickness of sandstone ,porosity ,permeability and oil saturation .In Chang3 stratum, sort I has the best physical character but few distribution, and sort II is abroad distribution especially in Chang3₃ stratum. In Chang4+5 stratum I is most distribution, III is the least.The Chang3-4+5 stratum in the studied area was defined delta front sedimentary by means of analysis of thickness sandstone, characters sedimentary facies ,sequence of single well, ratio of thickness of sand and mud, physical and log curve characters and sedimentary structure type, and growth five kinds sedimentary subficies in the studied area..The enrichment area of oil is controlled by litho logical and physical of reservoir, and it has important collocated relationship with up-incline direction of stratum and local promontory.The enrichment of oil area are predicted as following: The advantage areas accumulation in Chang4+52 reservoir located Bail32,ShanlO7 and Wu23. The re are 4 advantage areas accumulation in Chang3,they are Hua54,ShanlO6,Wu22 and South ShanZhuang area.