The gallery method for calculating well flow rates under steady-state filtration, developed by Academician A. P. Krylov, is widely used in the production of oil fields with a water-drive reservoir regime. An analysis of this method as applied to confined infinite aquifers shows that it can quite well be used for approximate hydrogeological calculations of ring water intakes of groundwater. In this case, the rows of production wells are conditionally replaced by galleries identical to them in outline and dimensions. Oil production from a reservoir with a water-drive regime leads to the simultaneous movement of oil and water in it, i.e., to two-phase filtration, which, in hydrodynamic calculations, is replaced by what is essentially single-phase filtration through the ratio of the dynamic viscosities of oil and water.