The Lower Jurassic Arhe Formation in Tugerming Region is typical braiedd river deltaic sediment and could be divided into deltaic plain and deltaic front subfacies.The formation consists of braided river channel

subaqueous distributary river channel

diara and river mouth bar subfacies formed by side deposition

filled in deposition

vertical deposition and front deposition.Reservoir interbed heterogeneity is controlled by sedimentary subfacies.Different subfacies possess different porosity and permeability.The physical property of braided channel sand bodies is the best;then that of the subaqueous distributary channel sand bodies

diaras and river mouth bars is secondary;that of river mouth sand bars of deltaic front subfacies is the last.The intrabed heterogeneity of the reservois is related to depositional manners.The permeability of the braided channel sand bodies and subaqueous distributary channel sand bodies formed by side deposition and filled in deposition is distributed in normal rhythm

and the highest permeability section is in the bottom;the permeability of diaras shows irregular distribution in vertical;that of river mouth sand bars shows reverse rhythmic distribution

and the peak permeability section is in the top.