This work is devoted to the joint use of physically based proxy models of different levels of complexity to determine the effective injection ratio factor. Effective injection factor is a parameter that reflects the proportion of injected fluid that enters the reservoir and does useful work to maintain reservoir pressure and displace oil from the reservoir. The selection of the effective injection factor when using a full-scale hydrodynamic simulator is difficult due to the high requirements for computational and time resources. Therefore, to calculate this coefficient, it is justified to use the simplified proxy modeling approach, which allows to evaluate the desired parameter in an acceptable time frame. The task of finding the effective injection ratio is related to inverse problems. The following were used as proxy models: a material balance model for the field as a whole and for a system of hydrodynamically connected blocks, a capacitance-resistance model (CRM) and a two-dimensional filtration model. The order of the models corresponds to the hierarchical principle "from simple to complex". Based on the history of oil field development (production, fluid injection, reservoir and bottomhole pressure), the effective injection coefficients were obtained, they were compared, and the analysis of the results was carried out.