Abstract:

Water flushing and biodegradation are the most important and most common cause of the formation of heavy oils.The degrees of water flushing and biodegradation mainly depend on the distribution of fractures and unconformities within a basin,the degree of the basin's post stage uplift and bottom water activifies.The first kind of heavy oil in Kenxi oil region,resulted from basin uplift and primary oil pool weathering,is characterized by high density,high viscosity,high content of sulphur and high solidifying point;the second kind of heavy oil,resulted from active bottom water and biodegradation,is characterized by high density,high viscosity,high content of sulphur and low solidifying point.