Optimal Study For Polymer Flooding In Formation Type ? Of Block Nan 5

Block Nan 5 of Saertu oilfield is located in the south of Daqing,with an area of 12.0km2,and the geological reserves is 6671.69×10~4t.The sedimentary facies of the block is inner and outer delta-frontal facies belts.There are 8 formations,30 sandstone groups,98 layers and 144 sedimentation units.The formation type ? is mainly concentrated in the sandstone section S?7-12 and PI5+61-7.The block is put into development in the year of 1956,the total number of well is 779,including 457 production wells and 322 injection wells.According to the reservoir characteristics of formation type ? in block Nan 5,the paper presents an optimal design of development schema for polymer flooding,in consideration of improving development effect and economic benefit.Frist,the paper gives an optimal design for the combination of formation type ?,and determine that the development object should be S?7-12.The geological reserves of the target layers is 739.22×10~4t.The thickness of drilling in sandstone(for the layers' effective thickness ?0.5m)is 7.8m,and the drilling effective thickness(for the layers' effective thickness ?0.5m)is 5.4m,which make a geological reserve of 600.35×10~4t.Secondly,combined with numerical simulation and economic evaluation,an optimal design for well pattern is given.The optimal result is a five-spot areal well pattern with a well spacing of 125 m,the number of newly drilled well is 621,including 335 production wells and 286 injection wells.According to the matching relation chart between polymer molecular weight and effective permeability,formula of injection pressure and injection speed,the polymer molecular weigh,solution concentration,polymer injection amount and injection rate are optimized.In the basis of the optimized scheme,a prediction of production and development effects are given.The predicted enhanced recovery efficiency is 10.44%,the cumulative oil production is 95.40×10~4t,the recoverable reserves increase by 62.68×10~4t.At last,the development monitoring and requirments of implement projects are presented.