Abstract: The existing planar equilibrium displacement evaluation method does not quantitatively consider the heterogeneity of the reservoir. For that reason, a new equation describing the relationship between water injection efficiency and cumulative oil production was built based on the dynamic displacement equation between injection and production wells with consideration of reservoir heterogeneity. The goal was to maximize water injection efficiency. The characteristic conditions of planar equilibrium displacement were obtained by derivation, on which the adjustment method for the injection–production structure of planar equilibrium displacement was developed. It is considered that the characteristic condition of equilibrium displacement in homogeneous reservoirs was that the ratios of injection volume to pore volume in all injection–production directions were the same; while that of equilibrium displacement in heterogeneous reservoirs was that the mentioned ratios in all injection–production directions were in a linear difference relationship. After adjusting the injection–production structure in the offshore BZ Oilfield by the planar equilibrium displacement method, the daily oil production increased by 155 m³, indicating the largely improved development effect. The results demonstrate that the planar equilibrium displacement method based on maximum water injection efficiency can be used guide the adjustment of the reservoir planar injection-production structure.