Effect analysis and countermeasures of advanced water flooding for ultra-low permeability reservoirs

The Chang 63 reservoir is an ultra-low permeability,low pressure reservoir with week natural energy.After advanced water injection,the reservoir was put on full-scale production.In the early production period,per well production was low,water cut was stable,and pressure dropped in some oil wells while rose in some water injection wells.It has been realized through research that with present well pattern,well spacing is too large to establish effective driving pressure system in some well groups,and it is necessary to reduce well spacing in order to form effective flooding;in addition,commingled water injection has resulted in non-corresponding horizons of injection to production,leading to low liquid production from oil wells.The adjustment measures proposed through the research include further subdividing layers,infilling well pattern,and reducing injection-production well spacing.