Physicochemical and Rheological Properties of Viscous Paraffin Oils

The physicochemical properties of hard-to-recover viscous oil with high paraffin content were evaluated relying on the analysis of information from oil characteristics database, compiled at the Institute of Petroleum Chemistry SB RAS. It is established that Russia is distinguished by the largest reserves of viscous paraffin oil (VPO) on the territory of Eurasia, where almost three quarters of the reserves are concentrated in the Volga-Ural oil and gas basin. The characteristics of properties of these oils under various conditions of their occurrence have been analysed. It is shown that VPO is more confined to terrigenous rocks, in which the reserves are 4.6 times greater than those in carbonate formations. The physicochemical properties of VPO in productive formations differing from each other in permeability and porosity are considered. It is established that in the case of high permeability of formations, the density of VPO increases (oil becomes heavier), coking ability, sulphur and resin content grow, the content of paraffins and the gas factor decrease. Viscous paraffin oils in reservoirs with different permeabilities have a positive pour point and are characterised by low gas content. In medium-and highly porous formations, VPOs are heavy, sulphurous, medium-resinous and medium-asphaltene, with low gas content. It is shown that in highly permeable and highly porous reservoirs, the content of paraffins in VPO is minimal and quite contrary the content of paraffins in oil is the greatest in low-permeable and low-porous reservoirs. The properties of high-hardening VPOs are revealed, which significantly differ from the properties of oils with negative pour point. High-setting VPOs differ from low-setting oils by medium density (low-setting oils are heavy), but very high viscosity; higher content of paraffins and oxygen, but lower content of resins, asphaltenes, sulphur (almost 2 times) and nitrogen; the gas factor is higher by 81 %.