Abstract: For low-permeability sandstone reservoirs with poor reservoir physical properties and strong heterogeneity, it is easy to form ineffective water injection cycle in the dominant injection-production direction in the moderate and high water-cut stages, resulting in low utilization of injected water and poor development effect. Therefore, based on the similar principle of seepage mechanics and hydroelectricity of the well group and the dynamic monitoring data acquired in the development process, a weighted calculation method was established to split the water injection rate in the longitudinal and planar directions. Three parameters, cumulative water intake rate per unit oil layer thickness in the injection-production direction, cumulative water intake ratio in the injection-production direction and water intake volume in the injection-production direction, were constrained to determine the quantitative characterization parameters on the plane in the dominant injection-production direction and their differentiation standard. The application proved that the quantitative characterization technology of the dominant injection-production direction had significant effect the fine water injection control in the ultra-high water-cut stage. After the water injection control of 177 wells, the water injection rate was reduced by 3 115 m³/d in the dominant injection-production direction and increased by 5 376 m³/d in the low water absorption direction, and the proportion of ineffective water injection decreased from about 20% to less than 10%. This study plays a guiding role in fine water injection control and remaining oil exploitation in the same reservoir.

Key words: dominant injection-production direction, water injection rate splitting, invalid water circulation, low-permeability sandstone reservoir