| This paper investigates the Chang4+5group of more than700wells in Triassic Yanchang Formation of Jiyuan area,Ordos basin. Make full use of the core, logging and logging data. Integrated the sedimentology and logging geology Closely. Research stratigraphic division,sedimentary facies,sand body distribution and reservoir characteristics.Chang4+5reservoir the favorable zone target preferred study area based on analysis of oil reservoirs.The results show that:The Chang4+5oil group of the study area can be divided into sand unit4+51and sand unit4+52,May be further divided into4+511、4+512、4+521and4+522four member; The sedimentary facies major for the delta front, and further can be classified as underwater distributary channel, underwater distributary Bay and underwater natural levee between the branch micro facies; Chang4+5reservoir rock types mainly fine-grained feldspathic sandstone. The porosity of the main types of intergranular pores, followed by feldspar dissolution porosity.The mercury curve flat section clearly show that the reservoir better sorting. Chang4+5reservoirs is a low porosity-ultra-low permeability reservoirs.Chang4+5oil group, according to the the reservoir classification criteria and data analysis in this area is mainly Class Ⅱ reservoirs, with a wide distribution, the thick characteristics. Reservoir type is mainly of lithologic, structural-lithologic deposit, reservoir enrichment is controlled by the oil source, deposition condition, reservoir, and many other factors. The wide distribution of hydrocarbon source rocks oriented area provides a rich source of oil accumulation, permeable sandstone and microcrack is the main channel of the oil and gas migration, a large area of distribution of delta underwater distributary channel sand body is the region’s most favorable reservoir. Finally, according to the characteristics of oil reservoirs analysis, the The favorable zone preferred target66, forecasting a total area of745.54km2and storability as26093.9×104t。... |
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