Research On The Technology Of Slow-speed Plugging Removal And Injection Enhancement In The Deep Part Of Water Injection Wells In Bohai Oilfield

With continuously water injection,near wellbore zone of the injection well will have blocked which will lead to increased injection pressure,injection volume decreased,affects the oil production.For the restoration of water injection wells in normal production,increase the yield of oil wells,injection wells must acidizing in a certain period.Over the years,the hydrofluoric acid is widely used in stimulation in many reservoirs.However,the action range of the hydrofluoric acid is small,hydrofluoric acid is mainly used to remove near wellbore blockage.Because most of the acid will be consumed with clay in the reservoir,and hydrofluoric acid and clay will generate insoluble which will block reservoir pore throat,thus affecting the permeability of sandstone reservoir.Bohai oilfield belongs to high porosity and permeability reservoir,in the process of water injection,the reservoir damage depth and more.And the deep stratum clay and other particles migration blocked oil flow channel will cause the production yield in the early period of acidification and decline rapidly in the late period.Rock core experiments and field research result suggest that high flow along with the oil and gas production yield will cause particle migration and reduce the formation permeability,accelerate the production decline.Foreign original improvement to the conventional mud acid is the so-called low concentration small delivery volume acidification method.HF is consumed in the near wellbore formation,unable to release the damage in the deep formation.So technology of deep retarded blocking removal and augmented injection in water injection well will become the new development direction of the technology of blocking removal and augmented injection in water injection well.Deep retarded acidizing technology is mainly through retarded acid in the formation of multistage hydrolysis reaction and regenerate acid,to achieve deep into the reservoir.Retarded acid and minerals in the formation continue to react,reduce the acid reaction velocity,delay effect of time between acid and rock,increasing the effective distance,enlarge acidizing radius.At the same time,by adding the efficient flowback agent,reducing the surface tension between acid and rock,accelerate the flowback of residual acid,reduce secondary pollution caused by residual acid in the formation.At the same time to solve the conventional retarded acid difficult to reconcile the contradictions of acid corrosion ability and speed performance.At present in Bohai oil field has been widely used and gets very good economic benefits.By studying of the technology of deep retarded blocking removal and augmented injection in water injection well in Bohai oilfield,this paper solves the problem of pollution in the deep formation due to various problems in the middle late period of oilfield development-Summary of acidizing blocking removal technology which has been implemented in offshore oilfield,and according to the geological research results,studying new technology and medicine about blocking removal and augmented injection in water injection well,tracking and evaluation the application effect of the technology of deep retarded blocking removal and augmented injection in water injection well,mainly research in fixed column acidification,temporary blocking shunt acidification and deep retarded acidification,developed a suitable acid system,at the same time,analysis and evaluation of various acidizing technique in the field application.