Abstract: Due to the different permeability of the medium-low permeability reservoirs in the offshore K oilfield, the physical properties of the reservoirs vary greatly. After water injection betting, the injecting pressure has risen rapidly and the water absorption capacity has decreased, so that the water injection could not get the demand of geological reservoirs. According to the static analytic data of geological reservoirs and the production dynamic analytic data of producers and injectors, oxygen activation test methods were used to establish the water absorption capacity and threshold condition of each layer. By using the results of test data,two methods of zonal injecting and increasing injecting pressure have been adopted, not only the total injection volume of the injectors has been increased and the natural decline of the benefited producers has slowed down, but also producing degree of medium-low permeability reservoirs has been improved, and improve the oilfields development effect. From the application effect of on-site injectors, it is worthy of popularization in medium-low permeability oilfields.