Objective At present, thin interlayers in some offshore medium and low permeability reservoirs are relatively developed, with complex pore structure, poor local physical properties, strong in-layer heterogeneity and other reservoir characteristics, which causes the overall situation of "no water injection, no oil production", and seriously restricts the oilfield development effect. Accordingly, a new nano injection enhancement system is proposed. It is necessary to develop new multifunctional augmented injection materials to meet the requirements of high-efficiency pressure reduction and long-term injection increase.

Methods The wettability, scale removal performance and permeability improvement performance of the system are studied through indoor experimental performance evaluation method.

Results The results show that the core is changed from hydrophilic to hydrophobic after nano solution treatment, and the average core wetting angle is increased by more than 20°, which makes the flowing water molecules slip and reduce the flow resistance. The nano solution helps to disperse the organic scale after stripping, with the elution rate reaching 92.3%, avoiding the secondary precipitation blockage of the stripped organic scale, and can effectively dissolve minerals, with the dissolution rate reaching 43%, playing a good role in unblocking and removing inorganic scale. After the core is displaced by nano solution, which increases the average permeability of artificial core by 32.6%, decreases the average injection pressure by 35.9%.

Conclusions The field application results show that the technology can significantly improve the water absorption capacity of water injection wells. After using the measures, the injection pressure decreased by 46.7%, the injection volume increased by 8 times, the water absorption index increased by 12.2 times, and the effective period was over 4 times than that of conventional acidification.