The article comprises of the conditions for the formation of reservoirs that retain their properties at great depths, as well as the geological features that are necessary for their safety during subsidence. Since the factors that ensure preservation are very diverse, their digitization is quite difficult; rather, we should say on considering many factors, the combination of which, and not necessarily all at once, is sufficient to forecast the existence of hydrocarbon deposits (and therefore, first of all, reservoirs) at depths that have become technologically accessible, that is, to expand the range geological forecast, which is technologically achieved.