Study Of The Sedimentary Facies And Reservoir Characteristics For Chang2Member In Da Donggou Area Of The Zhiluo Oil Field

Straight ROM oilfield Dadonggou region is located in Fuxian area,southeast of OrdosBasin.In order to speed up the process of exploration in this region and increase theexploration performance, it is necessary to carry out major research on reservoir chang-2oilgroup sedimentary facies and reservoir characteristics systematically to make clear the regionof chang-2reservoir distirbution of sand body，reservoir property, its inlfuential factors, thereservoir micro pore structure and heterogeneity characteristics, and to analysis the enirchmentregulation of oil and gas，thus to guide the next phase of petroleum exploration.Through the descirption of a large number of coring well core observation and thecomprehensive analysis of the well logging, mud logging，rock thin sections identiifcation andso on，combined with regional geological background，we have studied the rock types,sedimentary structure, provenance direction and sedimentary facies characteirstics of straightROM oilfield of Ordos Basin of chang2reservoir in detail. Result shows that the chang-2reservoir is a set of the lake delta sedimentary which is formed atferthe irvers flowing into thelake, and the provenance comes rfom the North-east of the basin. Delta front subfacies mainlydevelops in the region, with the development of microfacies types such as underseadistirbutary channel and distributary bay, etc.Dadonggou chang-2reservoir mainly consists of ifne-grained lithic feldspar sandstone,unstable components content such as feldspar and rock debirs is relatively high.The sortingand rounding of clastic particles separation is medium, with whole characteirzed by lowcompositional maturity, higher maturity structure,which shows that provenance relativelyclose to the region.Sandstone reservoir mainly develops primary intergranular pore, secondaryintergranular and intergranular pore and a small amount of mold pore.The pore structure ismainly the large-median-ifne throat pore structure.Dadonggou chang-2reservoir is divided into three types, different type of Sedimentaryfacie represents different the petrologic feature，physical characteirstics and pore structure.Generally speaking, type I reservoir is best developed but less distirbuted，type II reservoir is widely distributed.Finally it is guided by the oil and gas enirchment regulairty in the study area, based onsand body and sedimentary microfacies distirbution, combined with the porpermcharacteirstics and other physical property conditions，the range of profitability iscomprehensively predicted on the distirct chang-2reservoir.