The gallery method of calculating well flow rate at steady filtration, developed by Academician A. P. Krylov, is widely used in the operation of oil fields with water-pressure reservoir regime. Analysis of this method in relation to pressure unconfined aquifers shows that it can be used for approximate hydrogeological calculations of circular groundwater intakes. At the same time, rows of production wells are conditionally replaced by galleries identical to them in outline and size. Oil withdrawal from the reservoir with water pressure regime leads to simultaneous movement of oil and water in it, i.e. to two-phase filtration, which in hydrodynamic calculations through the ratio of dynamic viscosities of oil and water is replaced as if single-phase filtration.