weight: bold">Properties and Study on the Alteration of Heavy Oil of Jurassic in Wu-Xia Area,
By analyzing the physical and geochemical properties, the authors find some characteristics of the heavy oil. Based on these characteristics as well as the distribution of normal crude oil, heavy oil and oil sand, it is considered that the heavy oil in this region is mainly of secondary origin. Additionally, the alteration of heavy oil would be divided into biodegradation, oxygenation, water washing and diffusion respectively, of which the biodegradation and oxygenation are the most important. Finally, the accumulation model of heavy oil is established, which provides theoretical basis in predicting the distribution of heavy oil in the Wu-Xia area.