The third member of the Dongying Formation of C Oilfield in Bohai Sea is a thick-layer complex and strong heterogeneous fault-block reservoir with significant differences in reservoir properties and characteristics of medium-low porosity and medium-low permeability.Some water injection wells have under-injection problems at high pressure.In order to improve the development effect of water injection,the causes of under-injection are analyzed from the aspects of reservoir physical property,reservoir sensitivity,injected water compatibility,dynamic connectivity of injection and production,and corresponding countermeasures are formulated for the leading causes.The results show that there are two main reasons for under-injection:one is the incompatibility of injected water and formation water,fouling and fouling the reservoir;the other is the seepage resistance of low permeability waterflood zone is large and the dynamic connectivity of injection and production is poor.Therefore,the low permeability strong acid solution,high-temperature anti-scaling agent,and nano active system for the oilfield was developed to remove scale,prevent scale,and improve the seepage capacity of the low permeability water injection interval,to reduce pressure and increase injection.The field implementation has achieved the remarkable effect of reducing pressure and increasing injection.The validity period is extended,corresponding to the water injection of oil wells to achieve apparent results.
analysis of under-injection reasonscompatibility of injected waterlow permeability reservoirreduce pressure and increase injection
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