Analysis Of Reservoir Characteristics And Oil-Water Distribution Law Of Triassic Chang 6 Oil Formation In Dan 227 Well Area,Yongning Oilfield

This paper takes Dan 227 well block of Yongning oilfield in Ordos Basin as the research unit.Because the resource potential of Chang 6 reservoir of Triassic system in Dan 227 well area of Yongning oilfield is great.But its inefficient oilfield development because of complex reservoir genesis and unclear oil-water distribution law.In order to solve this problem,we’d like to make full use of the data of logging,drilling,experimental analysis,logging display and production test to make sure that the characteristics of Chang 6 ultra-low permeability reservoir are deeply studied.There are more than 370 wells in total.Through the fine division and correlation of strata,the stratigraphic framework of the whole region is established,and the stratigraphic characteristics and small layer structural evolution characteristics are summarized.And we also summarize the types of sedimentary microfacies and the distribution characteristics of facies belts in small layers and clarify the dominant areas of reservoir physical properties and the areas with relatively developed caprocks.On this basis,we could easily ensure the spatial distribution characteristics of the reservoir.And next we could find the main controlling factors of oil and gas accumulation and oil and water distribution law by putting useful data together into study pool like production test data and experimental analysis data.After a lot of research work,we get the conclusion that Chang 6 reservoir of Yanchang Formation in the study area is a typical near-source reservoir controlled by lithology.The updip tight sandstone or mudstone block trap directly controls the degree of oil and gas accumulation.In addition,sedimentary sand bodies also affect the degree of oil accumulation and the horizontal distribution law of oil and water.And we also find that the distribution of oil and gas in Chang 6₁ reservoir is continuous and basically covering the whole area.As for the Chang 6₂reservoir,the characteristics are different.Its oil and gas distribution in the reservoir is in shape of irregular potato,even the distribution of single reservoir is also discontinuous and limited.Moreover,the longitudinal distribution of oil and water shows the distribution characteristics like"upward oil and downward water,bidirectional occlusion".In addition,the time difference of acoustic wave should be greater than 218μs/m and the resistivity should be greater than18Ω·m for secondary logging interpretation especially of Chang 6₁¹ oil sand body.This study can play an important guiding role in the secondary logging interpretation or the review of old wells in the later period.