CHARACTERISTICS OF SEDIMENTARY MICROFACIES IN CHANG 6 OIL-BEARING FORMATION OF YANGCHANG FORMATION IN HUJIANSHAN-GENGWAN AREA, ORDOS BASIN

Chang 6 oil-bearing formation are mainly composed of gray or grayish fine sandstones and mudstone,belong to Yangchang formation in Hujianshan-Gengwan Area,Ordos Basin.According to the core describing,single-well facies and data analyzing of well and testing,as well as labor measurement,its sedimentary microfacies and the evolution and the distribution of the microfacies in every number have been studied.The result shows that front-delta is the main sedimentary system of Chang 6 in the studied area,the subaqueous distributary channel,channel-mouth bar,interdistributary,distal bar and front sheet sandstone are the main sedimentary microfacies.The distributary channel and channel-mouth bar are the main reservoir sands.The subaqueous distributary channels are joined and converged more greatly during Chang 62 than Chang 63.Different subaqueous distributary channel sandstone is crossed and connected much more distinctly and distributed bigger extent,bigger thickenss,during Chang 61 and is the major reservoirs in the study area.