A comparison between the compositions of the residual oil saturation of core material along the section of the Pashian horizon and crude oils produced from this formation revealed the deposition of solid paraffins in this reservoir, which resulted from the lowering of the reservoir temperature. The precipitation of solid paraffins as an individual phase is manifested in the increased contribution of nonbranched paraffinic structures, as compared with aromatic structures, to a mean molecule of residual oils; a higher amount of oil hydrocarbons relative to weakly altered residual oils; and a higher proportion of nonbranched high-molecular-mass homologues and a lower proportion of isoprenanes in C-12-C-36 alkanes. By pulse nuclear magnetic resonance, it was found that residual oil occurs in the form of a film on the surface of the sandstone pore space.