Formation and distribution of heavy oil and tar sands in China

On the basis of geological and geochemical data mainly from China, combined with data from other countries, it is found that formation and distribution of global heavy oil and tar sands is controlled by Alpine tectonic movements. They form two accumulation belts: the Alpine and the Circum-Pacific. Heavy oils and tar sands in western and eastern China belong to Alpine (Himalayan) Belt and Circum-Pacific Belt, respectively. The geochemical data shows that the progressive sequence of resistance of polycyclic aromatic hydrocarbons to biodegradation is triaromatic steroid hydrocarbons, chrysene series, phenanthrene series and naphthalene series. A certain amount of heavy oil in China originates from immature or low maturity oil, which is much higher in viscosity and in the hetero-compound fraction content than mature oil. Heavy oil and tar sands in China are widely distributed and abundant. It is estimated that the undiscovered heavy oil resources are 25 billion tons. Meanwhile, the potential of tar sands resources is also great. (C) 1999 Elsevier Science Ltd. All rights reserved.