Abstract:

Permo-Carboniferous system in North-Chjna platform is rich in coal,and has formed three enriched zones,the ages of which are getting younger. from north to south (fig.1). After Permian,the platform was activated and dismembered. The west part (Ordos) was depressed,the middle part (Shanxi plateau) uplifted and the east(the North-China plain) block-faulted. The coal beds underwent recoalification and formed a large amount of coal-formed gas as were deeply buried by Meso-Cenozoic sediments. It is observed that the coals in this platform are mainly cocking coal and anthracites,the major component of the gas is methane. Its potential reserve is up to 6?10¹²cu.m. with Ordos and the North-China plain to be the most favourable regions for gas prospecting. Three types of gas pools discovcred are also discussed in this paper: the water-sealed hysterogenitic gas pool (Yangquan Coalfield),the salt-sealed secondary gas pool(Wenliu Gasfield) and the argillaceous rock-sealed primary gas pool(Liujiazhuang Gasfield).