New distribution pattern of mudstone interlayer within batture bar reservoir of braided river-a case study of field outcrops in Wuguantun

Through observation,measurement and origin analysis of filed outcrops in Jurassic braided river deposits in Wuguantun,Datong,Shanxi,an accurate architecture anatomy study of 3-5 orders has been carried out.In vertical direction,it developed channel sand bodies in three periods and there were stable fine sediment exists between them.Within the single channel sand body,two 4th order architecture units,namely braided channels and channel bars,were developed,among which,the batture bar reservoir was the main type of sand bodies.Among the single batture bar reservoir,it developed multiple accreting bodies and between the accreting bodies it developed channels and falling-silt seams,which were filled by fine sandstone and there were no mudstone interlayer.Based on the architecture anatomy mentioned above,in combination with the sedimentary characteristics of the similar kinds,the distribution pattern of the batture bar reservoir of coarse-grained braided river and internal fine sedimentary units have been finally established.