The water saturation of characteristic pools of the Bashkir layer of the Perm region is experimentally proved: a limiting oil saturation, a transition zone, a filtration of pure oil, pure water and equal oil and water. Dependences of these watersaturations and on porosity are established. The parameter of a relative water saturation and calculated value of a cri - tical water saturations on its basis is determined. It is noted, that this allows to differentiate the pool reliably on various zones by a water saturation, to estimate an oil saturation of a pool in view of its transition zone, to predict results of approbation.