EXPULSION AND PRIMARY MIGRATION OF THE OIL DERIVED FROM COAL

The characteristics of coal pores and the interaction relationship bet ween hydrocarbons and pores in coal are analysed based on the typical example of oil from coal in Tuha Basin, pointing out that the interact ion between hydrocarbon molecules and coal pore surface particles is a major controlling factor of expulsion of oil from coal. Distribution characteristics of coal pores and the ability of hydrocarbon generatio n are inner factors of the expulsion of the oil from coal; tectonic co mpressive shear stress is an external force of the expulsion of oil fr om coal; expulsion of the oil from coal has greater geochromatographic effect than that from mudstone, the low mature stage (or vitrinite re flectance R-o is less than 0.9%) is advantageous to the coal-formed oi l expulsion and migration; hydrocarbons in the hydrocarbon network are linked with carrier beds (such as fault), through the pore network an d fissure which are connected with each other, which constitutes the m ain pathway of expulsion and migration.