Fine Injection-Production Technology for Bottom-Water Viscous Oil Reservoirs with Interlayers in Bohai Q Oilfield

In bottom-water viscous oil reservoirs with interlayers in Bohai Q Oilfield,the horizontal wells experienced poor liquid enhancement effect and the injected water flooding efficiency was unobvious.Researches on fine injection-production were carried out to solve this problem.The reservoir engineering method was used to deduce the expression of control coefficient reflecting the influence of interlayer parameters on productivity,and together with oil-water two-phase seepage productivity formula,the control effect of interlayer on liquid production capacity was studied.By means of numerical simulation and orthogonal tests,the reasons of poor water flooding efficiency were analyzed,and the influence of interlayer on water flooding was studied.In view of the extremely uneven water absorption on the upper and lower parts of interlayers for commingled water injection,a new interlayer-based intrastratal staged water injection technology was proposed and the optimal injection/production ratio for each stage of water injection was determined.The studied fine injection-production technology for bottom-water viscous oil reservoir with interlayer was applied in Bohai Q Oilfield and achieved satisfying effect.The research and application results show that under the same water cut,the larger the liquid production capacity,the greater the production pressure difference should be.For bottom water reservoirs with interlayers,the efficient development mode of"intrastratal staged water injection+liquid enhancement by large-capacity pump"has achieved good oil production enhancement performance,which can provide theoretical basis and production experience for efficient development of offshore viscous oil reservoirs.