In order to study ultrafine coal surface wettability change, used the operating manual DCAT21 which made in Germany to determine the five ultrafine coal powder that were made from different metamorphism coal.

Ten coals of different metamorphic degree have been investigated by the use of ~(13)C CP/MAS NMR technique,of which the spinlattice relaxation,variable contact time and dipolar dephasing experiments were performed on each coal.

Through analyzing the results of mercury injection experiments and static cryogenic nitrogen adsorption experiments,this paper discusses the control effect of coal metamorphic degree on the physical properties of coal reservoirs.

There exist lots of factors influencing the differencial distribution of permeability,from such aspects as the development of fracture system,the effective stress of coal-bed reservoirs,coal-bed tectonic evolution and coal-bearing rock metamorphic degree,the relationship among them and spacial distribution of highly permeable areas and the research progress are illustrated.