The paper deals with the results of complex lithology-facies examination of the UV1 1 layer within the Middle Ob group of fields. It is found that in the area under investigation, the layer was formed in the littoral-marine and shallow-water marine conditions under the effect of waves and currents. A paleogeographic chart has been constructed for the period of the UV1 1 layer generation in the Vasyuganian formation; forecast has been made as to the development of improved reservoir rocks.