Abstract: In XX33-1S oilfield,the fluvial reservoirs are characterized by big variations in lateral direction,low drilled rate of sand bodies and one reservoir type for one sandstone type,which brings great difficulties for reservoir exploration.In order to make a fast and efficient evaluation on the oilfield,a series of techniques,namely the macroscopic reservoir description technique under the sequence constraint,the fine description technique along the boundary and the internal sand bodies and the quantitative description technique of sand bodies have been applied to look for potential sand bodies outside the wells so as to find out more reserves in evaluation stage and achieve the purpose of making clear the fine reserve scale.