Characteristics and productivity control of Chang 4 + 5 oil-bearing sandstone reservoir in Baoziwan area,Ordos Basin

The characteristics Chang 4 + 5 oil-bearing sandstone reservoir in Baoziwan area,Ordos Basin is comprehensively studied by means of various analytical methods.It is shown that the Chang 4 + 5 sandstone reservoir is a set of continental lake delta depositional body,its lithology is mainly fine-grained feldspar sandstone and fine-grain of debris feldspar sandstone.The reservoir space is mainly residual intergrain pores and feldspar solution pore.The reservoir is of poor property,and belongs to typical low-porosity ultra-low permeability reservoir.The reservoir evaluation standard suitable to the reservoir is established and the comprehensive evaluation of the reservoir is carried out based on sedimentary type,sand-body lithology,diagenesis and pore structure.It is found that the productivity of the reservoirs is controlled by the classification of reservoirs.In the studied area,Ⅰtype reservoirs are developed well,which are of the highest single-well productivity,Ⅱtype reservoirs are also developed well,which are of highersingle-well productivity,and Ⅲ type reservoirs are not developed,which have no productivity.